bluuebunny/crossref_metadata_2025 huggingface dataset:
Aptamers That Preferentially Bind Type IVB Pili and Inhibit Human Monocytic-Cell Invasion by
Salmonella enterica
Serovar Typhi
Authors: Pan Qin , Zhang Xiao-Lian , Wu Hong-Yan , He Pan-Wen , Wang Fubin , Zhang Ming-Sheng , Hu Jian-Ming , Xia Bing , Wu Jianguo
Published: September 2005

Salmonella enterica
serovar Typhi is an important pathogen exclusively for humans and causes typhoid or enteric fever. It has been shown that type IVB pili, encoded by the
S. enterica
serovar Typhi
pil
operon located in
Salmonella
pathogenicity island 7, are important in the pathogenic process. In this study, by using both an adhesion-invasion assay and fluorescence quantitative PCR analysis, we demonstrated that the entry of type IVB piliated
S. enterica
serovar Typhi A21-6 (
pil
+
Km
r
) into human THP-1 monocytic cells was greater than that of a nonpiliated
S. enterica
serovar Typhi
pilS
::Km
r
(
pil
mutant) strain. We have applied a systematic evolution of ligands by exponential enrichment approach to select oligonucleotides (aptamers) as ligands that specifically bind to type IVB pili. Using this approach, we identified a high-affinity single-stranded RNA aptamer (S-PS
8.4
) as a type IVB pilus-specific ligand and further found that the selected aptamer (S-PS
8.4
) could significantly inhibit the entry of the piliated strain (but not that of the nonpiliated strain) into human THP-1 cells. The binding affinities between aptamers and pre-PilS (structural protein of type IVB pili) were determined by nitrocellulose filter-binding assays, and the

K
d

value was determined to be 8.56 nM for the S-PS
8.4
aptamer alone. As an example of an aptamer against type IVB pili of
S. enterica
serovar Typhi, the aptamer S-PS
8.4
can serve as a tool for analysis of bacterial type IVB pilus-host cell interactions and may yield information for the development of putative new drugs against
S. enterica
serovar Typhi bacterial infections, useful both in prevention of infection and in therapeutic treatment.
Neuraminidase Inhibitor-Resistant Influenza Viruses May Differ Substantially in Fitness and Transmissibility
Authors: Yen Hui-Ling , Herlocher Louise M. , Hoffmann Erich , Matrosovich Mikhail N. , Monto Arnold S. , Webster Robert G. , Govorkova Elena A.
Published: September 2005

Mutations of the conserved residues of influenza virus neuraminidase (NA) that are associated with NA inhibitor (NAI) resistance decrease the sialidase activity and/or stability of the NA, thus compromising viral fitness. In fact, clinically derived NAI-resistant variants with different NA mutations have shown different transmissibilities in ferrets (M. L. Herlocher, R. Truscon, S. Elias, H. Yen, N. A. Roberts, S. E. Ohmit, and A. S. Monto, J. Infect. Dis. 190:1627-1630, 2004). Molecular characterization of mutant viruses that have a homogeneous genetic background is required to determine the effect of single mutations at conserved NA residues. We generated recombinant viruses containing either the wild-type NA (RG WT virus) or a single amino acid change at NA residue 119 (RG E119V-NA virus) or 292 (RG R292K-NA virus) in the A/Wuhan/359/95 (H3N2) influenza virus background by reverse genetics. Both mutants showed decreased sensitivity to oseltamivir carboxylate, and the RG R292K-NA virus showed cross-resistance to zanamivir. We also observed differences between the two mutants in NA enzymatic activity and thermostability. The R292K mutation caused greater reduction of sialidase activity and thermostability than the E119V mutation. The NA defect caused by the R292K mutation was associated with compromised growth and transmissibility, whereas the growth and transmissibility of the RG E119V-NA virus were comparable to those of RG WT virus. Our results suggest that NAI-resistant influenza virus variants may differ substantially in fitness and transmissibility, depending on different levels of NA functional loss.
Atomic Force Microscopy Study of the Effect of Antimicrobial Peptides on the Cell Envelope of
Escherichia coli
Authors: Meincken M. , Holroyd D. L. , Rautenbach M.
Published: September 2005

The influences of the antibacterial magainin 2 and PGLa from the African clawed frog (
Xenopus laevis
) and the hemolytic bee venom melittin on
Escherichia coli
as the target cell were studied by atomic force microscopy (AFM). Nanometer-scale images of the effects of the peptides on this gram-negative bacterium's cell envelope were obtained in situ without the use of fixing agents. These high-resolution AFM images of the surviving and intact target cells before and after peptide treatment showed distinct changes in cell envelope morphology as a consequence of peptide action. Although all three peptides are lytic to
E. coli
, it is clear from this AFM study that each peptide causes distinct morphological changes in the outer membrane and in some cases the inner membrane, probably as a consequence of different mechanisms of action.
Sophorolipids, Microbial Glycolipids with Anti-Human Immunodeficiency Virus and Sperm-Immobilizing Activities
Authors: Shah Vishal , Doncel Gustavo F. , Seyoum Theodoros , Eaton Kristin M. , Zalenskaya Irina , Hagver Rena , Azim Abul , Gross Richard
Published: September 2005

The increased incidence of human immunodeficiency virus (HIV)/AIDS disease in women aged 15 to 49 years has identified the urgent need for a female-controlled, efficacious, and safe vaginal topical microbicide. To meet this challenge, sophorolipid (SL) produced by
Candida bombicola
and its structural analogs have been studied in this report for their spermicidal, anti-HIV, and cytotoxic activities. The sophorolipid diacetate ethyl ester derivative is the most potent spermicidal and virucidal agent of the series of SLs studied. Its virucidal activity against HIV and sperm-immobilizing activity against human semen are similar to those of nonoxynol-9. However, it also induced enough vaginal cell toxicity to raise concerns about its applicability for long-term microbicidal contraception. Its structure-activity relationship has been established for creating new analogs with less cytotoxicity and higher activity.
Multicenter Study To Determine Antibody Concentrations and Assess the Safety of Administration of INH-A21, a Donor-Selected Human Staphylococcal Immune Globulin, in Low-Birth-Weight Infants
Authors: Capparelli Edmund V. , Bloom Barry T. , Kueser Tom J. , Oelberg David G. , Bifano Ellen M. , White Robert D. , Schelonka Robert L. , Pearlman Stephen A. , Patti Joseph , Hetherington Seth V.
Published: September 2005

Nosocomial or late-onset sepsis is a common complication among premature infants, with a frequency inversely correlated with birth weight. Increased susceptibility to infection is due in part to an immature humoral (antibody-mediated) immune response. This study investigated the pharmacokinetics (PKs) and safety of a donor-selected specific intravenous immune globulin (IVIG) preparation, INH-A21 (Veronate), for prevention of sepsis in premature infants. Thirty-six infants weighing between 500 and 1,250 g during the first postnatal week were eligible to begin a series of up to four intravenous infusions of 500 or 750 mg/kg of body weight INH-A21. Blood samples were analyzed for antibodies against the Ser-Asp dipeptide repeat G (SdrG) and clumping factor A (ClfA) surface proteins of staphylococci. Sparse sampling and population PK analyses were performed to derive PK parameters. Following administration of the 500- and 750-mg/kg doses, the estimated average steady-state levels of anti-ClfA were 6.1 U/ml and 9.2 U/ml, respectively, and those of anti-SdrG were 5.2 U/ml and 7.7 U/ml, respectively. The elimination half-lives for anti-ClfA and anti-SdrG were 719 h and 701 h, respectively, and the clearances were 0.18 ml/h and 0.21 ml/h, respectively. In the final model, the values of the PK parameters were independent of gestational age. Both doses of INH-A21 were well tolerated, and the safety profile was similar to those of other IVIG preparations. These results suggest that a shorter dosing interval should be utilized between the first and second doses to achieve and maintain higher titers of anti-ClfA and anti-SdrG antibodies. Further studies examining INH-A21 for the prevention of late-onset sepsis in infants within the weight range studied are warranted.
Evaluation of LBM415 (NVP PDF-713), a Novel Peptide Deformylase Inhibitor, for Treatment of Experimental
Mycoplasma pneumoniae
Pneumonia
Authors: Fonseca-Aten Monica , Salvatore Christine M. , Mejías Asunción , Ríos Ana M. , Chávez-Bueno Susana , Katz Kathy , Gómez Ana M. , McCracken George H. , Hardy R. Doug
Published: September 2005

Mycoplasma pneumoniae
is a major cause of community-acquired pneumonia. We evaluated the efficacy of LBM415, a novel peptide deformylase inhibitor antimicrobial agent, for the treatment of
M. pneumoniae
pneumonia in a mouse model. Eight-week-old BALB/c mice were intranasally inoculated once with 10
7
CFU of
M. pneumoniae
. Groups of mice were treated with LBM415 (50 mg/kg of body weight) or placebo subcutaneously daily for 13 days, starting 24 h after inoculation. Groups of mice were evaluated at the baseline; at days of treatment 1, 3, 6, and 13; and at 7 days after treatment. The MIC of LBM415 against
M. pneumoniae
was <0.005 μg/ml. LBM415-treated mice had significantly lower bronchoalveolar lavage fluid
M. pneumoniae
concentrations than placebo-treated mice on days 6 and 13 of treatment. Compared with placebo treatment, therapy with LBM415 significantly decreased lung histopathology scores at days 3, 6, and 13 of treatment and at 7 days after treatment. Airway obstruction was significantly lower in LBM415-treated mice than in placebo-treated mice on days 1, 3, and 6 of treatment and after 7 days of therapy, while airway hyperresponsiveness was significantly lower only on day 3 of therapy. The bronchoalveolar lavage fluid concentrations of tumor necrosis factor alpha, gamma interferon (IFN-γ), interleukin-6 (IL-6), IL-12, KC (functional IL-8), monocyte chemotactic protein 1, macrophage inflammatory protein 1α, monokine induced by IFN-γ, and IFN-inducible protein 10 were significantly reduced in LBM415-treated mice compared with the levels in placebo-treated mice. There were no differences in the bronchoalveolar lavage fluid concentrations of granulocyte-macrophage colony-stimulating factor, IL-1β, IL-2, IL-4, IL-5, and IL-10 between the two groups of mice. LBM415 therapy had beneficial microbiologic, histologic, respiratory, and immunologic effects on acute murine
M. pneumoniae
pneumonia.
Efficacy and Safety of a Novel Once-Daily Extended-Release Ciprofloxacin Tablet Formulation for Treatment of Uncomplicated Urinary Tract Infection in Women
Authors: Fourcroy Jean L. , Berner Bret , Chiang Yu-Kun , Cramer Marilou , Rowe Lynne , Shore Neal
Published: September 2005

The efficacy and safety of a novel once-daily extended-release ciprofloxacin (ciprofloxacin ER) 500-mg dose were compared with those of an immediate-release ciprofloxacin (ciprofloxacin IR) 250-mg twice-daily dose, each administered orally for 3 days in the treatment of acute uncomplicated urinary tract infection (uUTI) in women. Adult female outpatients (mean age, 39 years) with clinical signs and symptoms of acute uUTI and a positive pretreatment urine culture (≥10
5
CFU/ml) were enrolled in a multicenter, randomized, double-blind, noninferiority trial. Patients were assessed at a test-of-cure visit (4 to 11 days posttreatment) and a late-posttreatment visit (4 to 6 weeks posttreatment) for microbiological and clinical outcomes and safety. The primary efficacy endpoint and microbiological eradication rate at the test-of-cure visit in the ciprofloxacin ER group (254/272; 93.4%) were noninferior to those in the ciprofloxacin IR group (225/251; 89.6%) (95% confidence interval [CI] of difference, −0.99%, 8.59%). Clinical-cure rates at the test-of-cure visit were 85.7% (233/272) for ciprofloxacin ER and 86.1% (216/251) for ciprofloxacin IR (95% CI of difference, −6.37%, 5.57%). At the late-posttreatment visit, microbiological and clinical outcomes were similar for the two treatments and consistent with test-of-cure results. Both treatments were well tolerated, but the frequencies of nausea and diarrhea were lower in the ciprofloxacin ER group than in the ciprofloxacin IR group (nausea, ER, 0.6%; IR, 2.2%;
P
= 0.033; diarrhea, ER, 0.2%; IR, 1.4%;
P
= 0.037). Once-daily ciprofloxacin ER was safe, effective, and noninferior to twice-daily ciprofloxacin IR in the treatment of acute uUTI. Additionally, ciprofloxacin ER was associated with significantly reduced frequencies of nausea and diarrhea.
Relationship between the Level of Acquired Resistance to Gentamicin and Synergism with Amoxicillin in
Enterococcus faecalis
Authors: Aslangul Elisabeth , Ruimy Raymond , Chau Françoise , Garry Louis , Andremont Antoine , Fantin Bruno
Published: September 2005

In enterococci, intrinsic low-level resistance to gentamicin does not abolish synergism with a cell wall-active antibiotic while high-level resistance due to acquired aminoglycoside-modifying enzymes does. To study the impact of intermediate levels of resistance to gentamicin (64 < MIC < 500 μg/ml), we selected in vitro three consecutive generations of mutants of
Enterococcus faecalis
JH2-2 with MICs of gentamicin at 128 μg/ml for G1-1477, 256 μg/ml for G2-1573, and 512 μg/ml for G3-1688.
E. faecalis
102, which is highly resistant to gentamicin by enzymatic inactivation was used as control. In in vitro killing curves experiments, gentamicin concentrations allowing bactericidal activity and synergism in combination with amoxicillin increased from 4 μg/ml (1/16th the MIC), 16 μg/ml (one-eighth the MIC), 64 μg/ml (one-quarter the MIC), and 256 μg/ml (one-half the MIC) for strains JH2-2, G1-1477, G2-1573 and G3-1688, respectively. As expected, no bactericidal effect of the combination or synergism could be obtained with strain 102. In rabbits with aortic endocarditis caused by strain G1-1477 or G2-1573, combination therapy with amoxicillin and gentamicin was significantly more active than amoxicillin alone (
P
< 0.05) but not in those infected with the strains G3-1688 and 102. Thus, intermediate levels of resistance to gentamicin was not associated with a loss of a beneficial effect of the gentamicin-amoxicillin combination in vivo even though higher concentrations of gentamicin were necessary to achieve in vitro synergism. Therefore, the use of an MIC of 500 μg/ml as a clinical cutoff limit to predict in vivo benefit of the combination remains a simple and effective tool.
Increase of Microcirculatory Blood Flow Enhances Penetration of Ciprofloxacin into Soft Tissue
Authors: Joukhadar Christian , Dehghanyar Pejman , Traunmüller Friederike , Sauermann Robert , Mayer-Helm Bernhard , Georgopoulos Apostolos , Müller Markus
Published: September 2005

The present study addressed the effect of microcirculatory blood flow on the ability of ciprofloxacin to penetrate soft tissues. Twelve healthy male volunteers were enrolled in an analyst-blinded, clinical pharmacokinetic study. A single intravenous dose of 200 mg of ciprofloxacin was administered over a period of approximately 20 min. The concentrations of ciprofloxacin were measured in plasma and in the warmed and contralateral nonwarmed lower extremities. The microdialysis technique was used for the assessment of unbound ciprofloxacin concentrations in subcutaneous adipose tissue. Microcirculatory blood flow was measured by use of laser Doppler flowmetry. Warming of the extremity resulted in an increase of microcirculatory blood flow by approximately three- to fourfold compared to that at the baseline (P< 0.05) in subcutaneous adipose tissue. The ratio of the maximum concentration (Cmax) of ciprofloxacin for the warmed thigh to theCmaxfor the nonwarmed thigh was 2.10 ± 0.90 (mean ± standard deviation;P< 0.05). A combined in vivo pharmacokinetic (PK)-in vitro pharmacodynamic (PD) simulation based on tissue concentration data indicated that killing ofPseudomonas aeruginosa(ATCC 27853 and two clinical isolates) was more effective by about 2 log10CFU/ml under the warmed conditions than under the nonwarmed conditions (P< 0.05). The improvement of microcirculatory blood flow due to the warming of the extremity was paralleled by an increased ability of ciprofloxacin to penetrate soft tissue. Subsequent PK-PD simulations based on tissue PK data indicated that this increase in tissue penetration was linked to an improved antimicrobial effect at the target site.
Resistance to Antimicrobial Peptides and Stress Response in
Mycoplasma pulmonis
Authors: Fehri Lina Fassi , Sirand-Pugnet Pascal , Gourgues Géraldine , Jan Gwenaël , Wróblewski Henri , Blanchard Alain
Published: September 2005

Antimicrobial peptides are widely distributed in nature, and in vertebrates, they play a key function in the innate immune defense system. It is generally agreed that these molecules may provide new antibiotics with therapeutic value. However, there are still many unsolved questions regarding the mechanisms underlying their antimicrobial activity as well as the mechanisms of resistance evolved by microorganisms against these molecules. The second point was addressed in this study. After determining the activity of 10 antimicrobial peptides against
Mycoplasma pulmonis
, a murine respiratory pathogen, the development of resistance was investigated. Following in vitro selection using subinhibitory concentrations of peptides, clones of this bacterium showing increased resistance to melittin or gramicidin D were obtained. For some of the clones, a cross-resistance was observed between these two peptides, in spite of their deep structural differences, and also with tetracycline. A proteomic analysis suggested that the stress response in these clones was constitutively activated, and this was confirmed by finding mutations in the
hrcA
gene; in mycoplasmas, bacteria which lack alternative sigma factors, the HrcA protein is supposed to play a key role as a negative regulator of heat shock proteins. By complementation of the
hrcA
mutants with the wild-type gene, the initial MICs of melittin and gramicidin D decreased to values close to the initial ones. This indicates that the resistance of
M. pulmonis
to these two antimicrobial peptides could result from a stress response involving HrcA-regulated genes.
In Vitro and In Vivo Antibacterial Activities of SM-216601, a New Broad-Spectrum Parenteral Carbapenem
Authors: Ueda Yutaka , Kanazawa Katsunori , Eguchi Ken , Takemoto Koji , Eriguchi Yoshiro , Sunagawa Makoto
Published: September 2005

SM-216601 is a novel parenteral 1β-methylcarbapenem. In agar dilution susceptibility testing, the MIC of SM-216601 for 90% of the methicillin-resistant
Staphylococcus aureus
(MRSA) strains tested (MIC
90
) was 2 μg/ml, which was comparable to those of vancomycin and linezolid. SM-216601 was also very potent against
Enterococcus faecium
, including vancomycin-resistant strains (MIC
90
= 8 μg/ml). SM-216601 exhibited potent activity against penicillin-resistant
Streptococcus pneumoniae
, ampicillin-resistant
Haemophilus influenzae
,
Moraxella catarrhalis
,
Escherichia coli
,
Klebsiella pneumoniae
, and
Proteus mirabilis
, with MIC
90
s of less than 0.5 μg/ml, and intermediate activity against
Citrobacter freundii
,
Enterobacter cloacae
,
Serratia marcescens
, and
Pseudomonas aeruginosa
. The therapeutic efficacy of SM-216601 against experimentally induced infections in mice caused by
S. aureus
,
E. faecium
,
E. coli
, and
P. aeruginosa
reflected its in vitro activity and plasma level. Thus, SM-216601 is a promising candidate for nosocomial bacterial infections caused by a wide range of gram-positive and gram-negative bacteria, including multiresistant pathogens.
Inhibition of Hepatitis C Virus Replication by Antimonial Compounds
Authors: Hwang Der-Ren , Lin Ren-Kuo , Leu Guang-Zhou , Lin Tiao-Yin , Lien Tzu-Wen , Yu Ming-Chen , Yeh Chau-Ting , Hsu John T.-A.
Published: September 2005

Chronic hepatitis C virus (HCV) infection is a worldwide health problem causing serious complications, such as liver cirrhosis and hepatoma. Alpha interferon (IFN-α) or its polyethylene glycol-modified form combined with ribavirin is the only recommended therapy. However, an alternative therapy is needed due to the unsatisfactory cure rate of the IFN-based therapy. Using a modified reporter assay based on the HCV subgenomic-replicon system, we found that sodium stibogluconate (SSG), a compound used for leishmania treatment, suppressed HCV replication. We have previously reported that SSG is effective at inhibiting HCV replication in a cell line permissive for HCV infection/replication and in an ex vivo assay using fresh human liver slices obtained from patients infected with HCV (26). In this study, we show that the SSG 50% inhibitory dose for HCV replication is 0.2 to 0.3 mg/ml (equivalent to 345 to 517 μM of Sb) in the HCV subgenomic-replicon system. We also found that SSG and IFN-α exert a strong synergistic anti-HCV effect in both the traditional isobologram analysis and the median effect principle (CalcuSyn analysis). The combination of SSG and IFN-α could sustain the antiviral response better than SSG or IFN-α alone. The results suggest that SSG may be a good drug candidate for use in combination with other therapeutics, such as IFN-α and ribavirin, to treat HCV infection.
Antistaphylococcal Activity of Ceftobiprole, a New Broad-Spectrum Cephalosporin
Authors: Bogdanovich Tatiana , Ednie Lois M. , Shapiro Stuart , Appelbaum Peter C.
Published: September 2005

Ceftobiprole (formerly BAL9141), the active component of the prodrug BAL5788 (ceftobiprole medocaril), is a novel cephalosporin with expanded activity against gram-positive bacteria. Among 152
Staphylococcus aureus
isolates, including 5 vancomycin-intermediate and 2 vancomycin-resistant strains, MIC
50
and MIC
90
values for ceftobiprole were each 0.5 μg/ml against methicillin-susceptible strains and 2 μg/ml against methicillin-resistant strains. Against 151 coagulase-negative staphylococci (including 4 vancomycin-intermediate strains), MIC
50
and MIC
90
values were, respectively, 0.125 μg/ml and 1 μg/ml against methicillin-susceptible and 1 μg/ml and 2 μg/ml against methicillin-resistant strains. Teicoplanin was less active than vancomycin against coagulase-negative strains. Linezolid, quinupristin-dalfopristin, and daptomycin were active against all strains, whereas increased MICs for amoxicillin-clavulanate, cefazolin, minocycline, gentamicin, trimethoprim-sulfamethoxazole, levofloxacin, rifampin, mupirocin, fusidic acid, and fosfomycin were sometimes observed. At 2× MIC, ceftobiprole was bactericidal against 11 of 12 test strains by 24 h. Prolonged serial passage in the presence of subinhibitory concentrations of ceftobiprole failed to select for clones with MICs >4 times those of the parents; the maximum MIC achieved for ceftobiprole after 50 passages (in 1 of 10 strains) was 8 μg/ml. Single-passage selections showed very low frequencies of resistance to ceftobiprole irrespective of genotype or phenotype; the maximal ceftobiprole MIC of recovered clones was 8 μg/ml.
Glycopeptide ResistancevanAOperons inPaenibacillusStrains Isolated from Soil
Authors: Guardabassi Luca , Perichon Bruno , van Heijenoort Jean , Blanot Didier , Courvalin Patrice
Published: September 2005

The sequence and gene organization of thevanoperons in vancomycin (MIC of >256 μg/ml)- and teicoplanin (MIC of ≥32 μg/ml)-resistantPaenibacillus thiaminolyticusPT-2B1 andPaenibacillus apiariusPA-B2B isolated from soil were determined. Both operons had regulatory (vanRandvanS), resistance (vanH,vanA, andvanX), and accessory (vanY,vanZ, andvanW) genes homologous to the corresponding genes in enterococcalvanAandvanBoperons. ThevanAPToperon inP. thiaminolyticusPT-2B1 had the same gene organization as that ofvanAoperons whereasvanAPAinP. apiariusPA-B2B resembledvanBoperons due to the presence ofvanWupstream from thevanHAXcluster but was closer tovanAoperons in sequence. ReferenceP. apiariusstrains NRRL B-4299 and NRRL B-4188 were found to harbor operons indistinguishable fromvanAPAby PCR mapping, restriction fragment length polymorphism, and partial sequencing, suggesting that this operon was species specific. As in enterococci, resistance was inducible by glycopeptides and associated with the synthesis of pentadepsipeptide peptidoglycan precursors ending ind-Ala-d-Lac, as demonstrated byd,d-dipeptidase activities, high-pressure liquid chromatography, and mass spectrometry. The precursors differed from those in enterococci by the presence of diaminopimelic acid instead of lysine in the peptide chain. Altogether, the results are compatible with the notion thatvanoperons in soilPaenibacillusstrains and in enterococci have evolved from a common ancestor.
Kinetic Properties of Four Plasmid-Mediated AmpC β-Lactamases
Authors: Bauvois Cédric , Ibuka Akiko Shimizu , Celso Almeida , Alba Jimena , Ishii Yoshikazu , Frère Jean-Marie , Galleni Moreno
Published: September 2005

The heterologous production in
Escherichia coli
, the purification, and the kinetic characterization of four plasmid-encoded class C β-lactamases (ACT-1, MIR-1, CMY-2, and CMY-1) were performed. Except for their instability, these enzymes are very similar to the known chromosomally encoded AmpC β-lactamases. Their kinetic parameters did not show major differences from those obtained for the corresponding chromosomal enzymes. However, the

K
m

values of CMY-2 for cefuroxime, cefotaxime, and oxacillin were significantly decreased compared to those of the chromosomal AmpC enzymes. Finally, the susceptibility patterns of different
E. coli
hosts producing a plasmid- or a chromosome-encoded class C enzyme toward β-lactam antibiotics are mainly due to the overproduction of the β-lactamase in the periplasmic space of the bacteria rather than to a specific catalytic profile of the plasmid-encoded β-lactamases.
Antibacterial Activity of REP8839, a New Antibiotic for Topical Use
Authors: Critchley Ian A. , Young Casey L. , Stone Kimberley C. , Ochsner Urs A. , Guiles Joseph , Tarasow Ted , Janjic Nebojsa
Published: September 2005

REP8839 is a novel methionyl-tRNA synthetase (MetS) inhibitor with potent antibacterial activity against clinical isolates of
Staphylococcus aureus
,
Streptococcus pyogenes
, and other clinically important gram-positive bacteria but little activity against gram-negative bacteria. All isolates of
S. aureus
, including strains resistant to methicillin, mupirocin, vancomycin, and linezolid were susceptible to REP8839 at concentrations of ≤0.5 μg/ml. REP8839 was also active against
Staphylococcus epidermidis
, including multiply resistant strains (MIC, ≤0.25 μg/ml). All
S. pyogenes
isolates were susceptible to REP8839 at concentrations of ≤0.25 μg/ml, suggesting that MetS2, a second enzyme previously identified in
Streptococcus pneumoniae
, was not present in this organism. REP8839 was highly bound to the protein of human serum, and activity was not greatly influenced by inoculum size but was affected by pH, exhibiting optimal antibacterial activity in a neutral medium rather than a weak acidic medium. Like mupirocin, REP8839 exhibited bacteriostatic activity against key pathogens. The emergence of mupirocin resistance in
S. aureus
highlights the need for a new topical antibiotic with the ability to inhibit high-level mupirocin-resistant strains and other emerging phenotypes, such as vancomycin-resistant and community-acquired methicillin-resistant isolates.
Ultrasonically Controlled Release of Ciprofloxacin from Self-Assembled Coatings on Poly(2-Hydroxyethyl Methacrylate) Hydrogels forPseudomonas aeruginosaBiofilm Prevention
Authors: Norris P. , Noble M. , Francolini I. , Vinogradov A. M. , Stewart P. S. , Ratner B. D. , Costerton J. W. , Stoodley P.
Published: September 2005

Indwelling prostheses and subcutaneous delivery devices are now routinely and indispensably employed in medical practice. However, these same devices often provide a highly suitable surface for bacterial adhesion and colonization, resulting in the formation of complex, differentiated, and structured communities known as biofilms. The University of Washington Engineered Biomaterials group has developed a novel drug delivery polymer matrix consisting of a poly(2-hydroxyethyl methacrylate) hydrogel coated with ordered methylene chains that form an ultrasound-responsive coating. This system was able to retain the drug ciprofloxacin inside the polymer in the absence of ultrasound but showed significant drug release when low-intensity ultrasound was applied. To assess the potential of this controlled drug delivery system for the targeting of infectious biofilms, we monitored the accumulation ofPseudomonas aeruginosabiofilms grown on hydrogels with and without ciprofloxacin and with and without exposure to ultrasound (a 43-kHz ultrasonic bath for 20 min daily) in an in vitro flow cell study. Biofilm accumulation from confocal images was quantified and statistically compared by using COMSTAT biofilm analysis software. Biofilm accumulation on ciprofloxacin-loaded hydrogels with ultrasound-induced drug delivery was significantly reduced compared to the accumulation of biofilms grown in control experiments. The results of these studies may ultimately facilitate the future development of medical devices sensitive to external ultrasonic impulses and capable of treating or preventing biofilm growth via “on-demand” drug release.
Unexpected Enzyme TEM-126: Role of Mutation Asp179Glu
Authors: Delmas J. , Robin F. , Bittar F. , Chanal C. , Bonnet R.
Published: September 2005

The clinical isolate
Escherichia coli
CF884 exhibited low-level resistance to ceftazidime (4 μg/ml) by a positive double-disk synergy test and apparent susceptibility to cefuroxime, cefotaxime, cefepime, cefpirome, and aztreonam. The enzyme implicated in this phenotype was a novel 180-kb plasmid-encoded TEM-type extended-spectrum β-lactamase designated TEM-126 which harbors the mutations Asp179Glu and Met182Thr. TEM-126 exhibited significant hydrolytic activity (
k
cat
, 2 s
−1
) and a

K
m

value of 82 μM against ceftazidime. Molecular dynamics simulations suggested that the substitution Asp179Glu induces subtle conformational changes to the omega loop which may favor the insertion of ceftazidime in the binding site and the correct positioning of the crucial residue Glu166. Overall, these results highlight the remarkable plasticity of TEM enzymes, which can expand their activity against ceftazidime by the addition of one carbon atom in the side chain of residue 179.
Sensitivity of
Candida albicans
Germ Tubes and Biofilms to Photofrin-Mediated Phototoxicity
Authors: Chabrier-Roselló Yeissa , Foster Thomas H. , Pérez-Nazario Nelissa , Mitra Soumya , Haidaris Constantine G.
Published: September 2005

Treatment of mucocutaneous and cutaneous
Candida albicans
infections with photosensitizing agents and light, termed photodynamic therapy (PDT), offers an alternative to conventional treatments. Initial studies using the clinically approved photosensitizer Photofrin demonstrated the susceptibility of
C. albicans
to its photodynamic effects. In the present study, we have further refined parameters for Photofrin-mediated photodynamic action against
C. albicans
and examined whether mechanisms commonly used by microorganisms to subvert either antimicrobial oxidative defenses or antimicrobial therapy, including biofilm formation, were operative. In buffer and defined medium, germ tubes preloaded with Photofrin retained their photosensitivity for up to 2 hours, indicating the absence of degradation or export of Photofrin by the organism. The addition of serum resulted in a gradual loss of photosensitivity over 2 hours. In contrast to an adaptive response by germ tubes to oxidative stress by hydrogen peroxide, there was no adaptive response to singlet oxygen-mediated stress by photodynamic action.
C. albicans
biofilms were sensitive to Photofrin-mediated phototoxicity in a dose-dependent manner. Finally, the metabolic activity of
C. albicans
biofilms following photodynamic insult was significantly lower than that of biofilms treated with amphotericin B for the same time period. These results demonstrate that several of the mechanisms microorganisms use to subvert either antimicrobial oxidative defenses or antimicrobial therapy are apparently not operative during Photofrin-mediated photodynamic treatment of
C. albicans
. These observations provide support and rationale for the continued investigation of PDT as an adjunctive, or possibly alternative, mode of therapy against cutaneous and mucocutaneous candidiasis.
Mutations Conferring Resistance to a Hepatitis C Virus (HCV) RNA-Dependent RNA Polymerase Inhibitor Alone or in Combination with an HCV Serine Protease Inhibitor In Vitro
Authors: Mo Hongmei , Lu Liangjun , Pilot-Matias Tami , Pithawalla Ron , Mondal Rubina , Masse Sherie , Dekhtyar Tatyana , Ng Teresa , Koev Gennadiy , Stoll Vincent , Stewart Kent D. , Pratt John , Donner Pam , Rockway Todd , Maring Clarence , Molla Akhteruzzaman
Published: September 2005

Compounds A-782759 (anN-1-aza-4-hydroxyquinolone benzothiadiazine) and BILN-2061 are specific anti-hepatitis C virus (HCV) agents that inhibit the RNA-dependent RNA polymerase and the NS3 serine protease, respectively. Both compounds display potent activity against HCV replicons in tissue culture. In order to characterize the development of resistance to these anti-HCV agents, HCV subgenomic 1b-N replicon cells were cultured with A-782759 alone or in combination with BILN-2061 at concentrations 10 times above their corresponding 50% inhibitory concentrations in the presence of neomycin. Single substitutions in the NS5B polymerase gene (H95Q, N411S, M414L, M414T, or Y448H) resulted in substantial decreases in susceptibility to A-782759. Similarly, replicons containing mutations in the NS5B polymerase gene (M414L or M414T), together with single mutations in the NS3 protease gene (A156V or D168V), conferred high levels of resistance to both A-782759 and BILN-2061. However, the A-782759-resistant mutants remained susceptible to nucleoside and two other classes of nonnucleoside NS5B polymerase inhibitors, as well as interferon. In addition, we found that the frequency of replicons resistant to both compounds was significantly lower than the frequency of resistance to the single compound. Furthermore, the dually resistant mutants displayed significantly reduced replication capacities compared to the wild-type replicon. These findings provide strategic guidance for the future treatment of HCV infection.
Molecular Evolution Perspectives on Intraspecific Lateral DNA Transfer of Topoisomerase and Gyrase Loci in
Streptococcus pneumoniae
, with Implications for Fluoroquinolone Resistance Development and Spread
Authors: Stanhope Michael J. , Walsh Stacey L. , Becker Julie A. , Italia Michael J. , Ingraham Karen A. , Gwynn Michael N. , Mathie Tom , Poupard James A. , Miller Linda A. , Brown James R. , Amrine-Madsen Heather
Published: September 2005

Fluoroquinolones are an important class of antibiotics for the treatment of infections arising from the gram-positive respiratory pathogen
Streptococcus pneumoniae
. Although there is evidence supporting interspecific lateral DNA transfer of fluoroquinolone target loci, no studies have specifically been designed to assess the role of intraspecific lateral transfer of these genes in the spread of fluoroquinolone resistance. This study involves a comparative evolutionary perspective, in which the evolutionary history of a diverse set of
S. pneumoniae
clinical isolates is reconstructed from an expanded multilocus sequence typing data set, with putative recombinants excluded. This control history is then assessed against networks of each of the four fluoroquinolone target loci from the same isolates. The results indicate that although the majority of fluoroquinolone target loci from this set of 60 isolates are consistent with a clonal dissemination hypothesis, 3 to 10% of the sequences are consistent with an intraspecific lateral transfer hypothesis. Also evident were examples of interspecific transfer, with two isolates possessing a
parE
-
parC
gene region arising from viridans group streptococci. The Spain 23F-1 clone is the most dominant fluoroquinolone-nonsusceptible clone in this set of isolates, and the analysis suggests that its members act as frequent donors of fluoroquinolone-nonsusceptible loci. Although the majority of fluoroquinolone target gene sequences in this set of isolates can be explained on the basis of clonal dissemination, a significant number are more parsimoniously explained by intraspecific lateral DNA transfer, and in situations of high
S. pneumoniae
population density, such events could be an important means of resistance spread.
High-Level Chromosomally Mediated Tetracycline Resistance inNeisseria gonorrhoeaeResults from a Point Mutation in therpsJGene Encoding Ribosomal Protein S10 in Combination with themtrRandpenBResistance Determinants
Authors: Hu Mei , Nandi Sobhan , Davies Christopher , Nicholas Robert A.
Published: September 2005

Neisseria gonorrhoeaebecomes resistant to tetracycline by two major mechanisms: expression of a plasmid-encoded TetM protein and mutations in endogenous genes (chromosomally mediated resistance). Early studies by Sparling and colleagues (P. F. Sparling F. A. J. Sarubbi, and E. Blackman, J. Bacteriol. 124:740-749, 1975) demonstrated that three genes were involved in high-level chromosomally mediated tetracycline resistance (MIC of tetracycline ≥ 2 μg/ml):ery-2(now referred to asmtrR),penB, andtet-2. While the identities of the first two genes are known, thetet-2gene has not been identified. We cloned thetet-2gene, which confers tetracycline resistance, from tetracycline-resistant clinical isolateN. gonorrhoeaeFA6140 and show that resistance is due to a single point mutation (Val-57 to Met) in therpsJgene (rpsJ1) encoding ribosomal protein S10. Moreover, the identical mutation was found in six distinct tetracycline-resistant clinical isolates in which the MIC of tetracycline was ≥2 μg/ml. Site-saturation mutagenesis of the codon for Val-57 identified two other amino acids (Leu and Gln) that conferred identical levels of resistance as the Met-57 mutation. The mutation maps to the vertex of a loop in S10 that is near the aminoacyl-tRNA site in the structure of the 30S ribosomal subunit fromThermus thermophilus, and the residue equivalent to Val-57 inT. thermophilusS10, Lys-55, is within 8 to 9 Å of bound tetracycline. These data suggest that large noncharged amino acids alter the rRNA structure near the tetracycline-binding site, leading to a lower affinity of the antibiotic.
Oral Therapy Using Nanoparticle-Encapsulated Antituberculosis Drugs in Guinea Pigs Infected with
Mycobacterium tuberculosis
Authors: Johnson Christine M. , Pandey Rajesh , Sharma Sadhna , Khuller G. K. , Basaraba Randall J. , Orme Ian M. , Lenaerts Anne J.
Published: September 2005

We evaluated the efficacy of nanoparticle-encapsulated antituberculosis drugs administered every 10 days versus that of daily nonencapsulated drugs against
Mycobacterium tuberculosis
aerosol infection in guinea pigs. Both treatments significantly reduced the bacterial count and lung histopathology, suggesting that the nanoparticle drug delivery system has potential in intermitted treatment of tuberculosis.
Efficacy of Telavancin (TD-6424), a Rapidly Bactericidal Lipoglycopeptide with Multiple Mechanisms of Action, in a Murine Model of Pneumonia Induced by Methicillin-Resistant
Staphylococcus aureus
Authors: Reyes Noe , Skinner Robert , Kaniga Koné , Krause Kevin M. , Shelton Josephine , Obedencio Glenmar P. , Gough Alexander , Conner Michael , Hegde Sharath S.
Published: September 2005

The efficacy of telavancin, a bactericidal lipoglycopeptide, was compared to that of vancomycin and linezolid against methicillin-resistant
Staphylococcus aureus
(MRSA) in a murine pneumonia model. Telavancin produced greater reductions in lung bacterial titer and mortality than did vancomycin and linezolid at human doses equivalent to those described by the area under the concentration-time curve. These results suggest the potential utility of telavancin for treatment of MRSA pneumonia.
The
erm
(T) Gene Is Flanked by IS
1216V
in Inducible Erythromycin-Resistant
Streptococcus gallolyticus
subsp.
pasteurianus
Authors: Tsai Jui-Chang , Hsueh Po-Ren , Chen Hsiao-Jan , Tseng Sung-Pin , Chen Pei-Yu , Teng Lee-Jene
Published: September 2005

We investigated the sequence and the genetic context of the
erm
(T) gene in six inducible erythromycin-resistant
Streptococcus gallolyticus
subsp.
pasteurianus
(formerly
S. bovis
biotype II.2) isolates. In all isolates, the
erm
(T) genes were flanked by two IS
1216V
-like elements with the same polarity and were found to be inserted in the chromosome.
parC
Mutations in Fluoroquinolone-Resistant
Borrelia burgdorferi
Authors: Galbraith Kendal M. , Ng Amanda C. , Eggers Betsy J. , Kuchel Craig R. , Eggers Christian H. , Samuels D. Scott
Published: September 2005

We have isolated in vitro fluoroquinolone-resistant mutants of the Lyme disease agent,
Borrelia burgdorferi
. Mutations in
parC
, which encodes a subunit of topoisomerase IV, were associated with loss of susceptibility to sparfloxacin, moxifloxacin, and Bay-Y3118, but not ciprofloxacin. This is the first description of fluoroquinolone resistance in the spirochete phylum.
Efficacy of 2-(3,4-Dimethyl-2,5-Dihydro-1H-Pyrrole-2-yl)-1-Methylethyl Pentanoate in a Murine Model of Invasive Aspergillosis
Authors: Dabur Rajesh , Diwedi S. K. , Yadav V. , Mishra V. , Singh Rambir , Singh H. , Sharma G. L.
Published: September 2005

2-(3,4-Dimethyl-2,5-dihydro-1H-pyrrole-2-yl)-1-methylethyl pentanoate, an antifungal compound, was found to be nontoxic to RAW cells up to a concentration of 312.5 μg/ml, whereas amphotericin B was lethal to all cells at 37.5 μg/ml. The treatment of
Aspergillus fumigatus
-infected mice with a dose of 200.0 mg of compound/kg of body weight increased their survival rate by 60%, with a decrease in CFU in organ tissues. The protection afforded by the compound against experimental aspergillosis was found to be dose dependent.
Penetration of Piperacillin and Tazobactam into Inflamed Soft Tissue of Patients with Diabetic Foot Infection
Authors: Legat F. J. , Krause R. , Zenahlik P. , Hoffmann C. , Scholz S. , Salmhofer W. , Tscherpel J. , Tscherpel T. , Kerl H. , Dittrich P.
Published: September 2005

We investigated the pharmacokinetics of piperacillin and tazobactam in the extracellular space fluid of inflamed soft tissues of six patients with diabetic foot infection using in vivo microdialysis and found similar penetration for piperacillin but not for tazobactam into inflamed and noninflamed soft tissue.
Interaction of the MexA and MexB Components of the MexAB-OprM Multidrug Efflux System of
Pseudomonas aeruginosa
: Identification of MexA Extragenic Suppressors of a T578I Mutation in MexB
Authors: Nehme Dominic , Poole Keith
Published: September 2005

A T578I mutation in MexB compromised the protein's contribution to antimicrobial resistance and negatively impacted its interaction with MexA. Mutations causing single amino acid changes in the C-terminal domain of MexA (R221H, L245F, E254K, and V259I) suppressed the antimicrobial susceptibility of a MexB
T578I
-expressing
Pseudomonas aeruginosa
strain and restored a MexA interaction with MexB
T578I
. These data confirm the importance of the MexA C-terminal region in MexB binding and the likely significance of the region surrounding T587I of MexB in MexA interaction.
Macrolide Resistance Mediated by a
Bifidobacterium breve
Membrane Protein
Authors: Margolles Abelardo , Moreno José Antonio , van Sinderen Douwe , de los Reyes-Gavilán Clara G.
Published: September 2005

A gene coding for a hypothetical membrane protein from
Bifidobacterium breve
was expressed in
Lactococcus lactis
. Immunoblotting demonstrated that this protein is located in the membrane. Phenotypical changes in sensitivity towards 21 antibiotics were determined. The membrane protein-expressing cells showed higher levels of resistance to several macrolides.
Contribution of Mutation at Amino Acid 45 of AcrR to
acrB
Expression and Ciprofloxacin Resistance in Clinical and Veterinary
Escherichia coli
Isolates
Authors: Webber Mark A. , Talukder Ashraf , Piddock Laura J. V.
Published: September 2005

Fluoroquinolone-resistant
Escherichia coli
isolates which overexpressed
acrB
and had a substitution at amino acid 45 of AcrR were complemented with wild-type
acrR
. Complementation led to increased sensitivity to ciprofloxacin and to ethidium bromide, suggesting that mutation at amino acid 45 of AcrR contributes to ciprofloxacin resistance.
Limited Polymorphism in the Dihydropteroate Synthetase Gene (
dhps
) of
Plasmodium vivax
Isolates from Thailand
Authors: Imwong Mallika , Pukrittayakamee Sasithon , Cheng Qin , Moore Catrin , Looareesuwan Sornchai , Snounou Georges , White Nicholas J. , Day Nicholas P. J.
Published: September 2005

The
dhps
sequences of 55
Plasmodium vivax
isolates (39 from Thailand and 16 from elsewhere) revealed mutant Pv
dhps
at codons 383 and/or 553 (A → G) in 33 isolates, all from Thailand. Mutations of Pv
dhps
and Pv
dhfr
were correlated. Multiple mutations were associated with high-grade sulfadoxine-pyrimethamine resistance.
Clevudine Inhibits Hepatitis Delta Virus Viremia: a Pilot Study of Chronically Infected Woodchucks
Authors: Casey John , Cote Paul J. , Toshkov Illia A. , Chu Chung K. , Gerin John L. , Hornbuckle William E. , Tennant Bud C. , Korba Brent E.
Published: September 2005

In a small controlled study, clevudine, a potent inhibitor of hepadnaviruses, including hepatitis B virus and woodchuck hepatitis virus, suppressed hepatitis delta virus (HDV) viremia in chronically infected woodchucks. Suppression was correlated with the marked reduction of woodchuck hepatitis virus surface antigen in individual animals, consistent with the concept that repression of surface antigen expression may be a useful antiviral strategy for HDV.
Genetic and Enzymatic Properties of Metallo-β
-
Lactamase VIM-5 from a Clinical Isolate of
Enterobacter cloacae
Authors: Gacar Gulcin G. , Midilli Kenan , Kolayli Fetiye , Ergen Kivanc , Gundes Sibel , Hosoglu Salih , Karadenizli Aynur , Vahaboglu Haluk
Published: September 2005

A VIM-5-producing
Enterobacter cloacae
isolate (EDV/1) was identified in a collection of clinical strains stored before 2002. The gene,
bla
VIM-5
, was located on a 2,712-bp BamHI-HindIII fragment of a 23-kbp (approximately) nonconjugative plasmid (pEDV5) in a class 1 integron as a single gene cassette.
Low Rates of Cutaneous Adverse Reactions to Alcohol-Based Hand Hygiene Solution during Prolonged Use in a Large Teaching Hospital
Authors: Graham M. , Nixon R. , Burrell L. J. , Bolger C. , Johnson P. D. R. , Grayson M. L.
Published: September 2005

We assessed cutaneous adverse reactions (CARs) to alcohol-based hand rub (ABHR) after the introduction of a hand hygiene culture change program at our institution. CARs were infrequent among exposed health care workers (HCWs) (13/2,750; 0.47%; 1 CAR per 72 years of HCW exposure) and were not influenced by the duration or intensity of ABHR use but were associated with the presence of irritant contact dermatitis.
Lower Nitric Oxide Susceptibility of Trivalent Antimony-Resistant Amastigotes ofLeishmania infantum
Authors: Holzmuller P. , Sereno D. , Lemesre J.-L.
Published: September 2005

We previously documented the induction ofLeishmaniaamastigote apoptosis by trivalent antimony (SbIII) and nitric oxide (NO). We demonstrate here that SbIII-resistant amastigotes were resistant to NO toxicity when delivered extracellularly by NO donors or intracellularly via macrophage activation. Shared biochemical targets for SbIII and NO resistance inLeishmaniaare discussed.
Inhibition of Class D β-Lactamases by Acyl Phosphates and Phosphonates
Authors: Adediran S. A. , Nukaga Michiyoshi , Baurin Stéphane , Frère J.-M. , Pratt R. F.
Published: September 2005

The susceptibility of typical class D β-lactamases to inhibition by acyl phosph(on)ates has been determined. To a large degree, these class D enzymes behaved very similarly to the class A TEM β-lactamase towards these reagents. Dibenzoyl phosphate stood out in both cases as a lead compound towards a new class of effective inhibitors.