bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-Resistance between Triclosan and Antibiotics in
Pseudomonas aeruginosa
Is Mediated by Multidrug Efflux Pumps: Exposure of a Susceptible Mutant Strain to Triclosan Selects
nfxB
Mutants Overexpressing MexCD-OprJ
Authors: Chuanchuen Rungtip , Beinlich Kerry , Hoang Tung T. , Becher Anna , Karkhoff-Schweizer RoxAnn R. , Schweizer Herbert P. 
Published: July 2002

ABSTRACT

Triclosan is an antiseptic frequently added to items as diverse as soaps, lotions, toothpaste, and many commonly used household fabrics and plastics. Although wild-type
Pseudomonas aeruginosa
expresses the triclosan target enoyl-acyl carrier protein reductase, it is triclosan resistant due to expression of the MexAB-OprM efflux system. Exposure of a susceptible Δ(
mexAB-oprM
) strain to triclosan selected multidrug-resistant bacteria at high frequencies. These bacteria hyperexpressed the MexCD-OprJ efflux system due to mutations in its regulatory gene,
nfxB
. The MICs of several drugs for these mutants were increased up to 500-fold, including the MIC of ciprofloxacin, which was increased 94-fold. Whereas the MexEF-OprN efflux system also participated in triclosan efflux, this antimicrobial was not a substrate for MexXY-OprM.
Therapeutic Potential of Human Neutrophil Peptide 1 against Experimental Tuberculosis
Authors: Sharma Sudhir , Verma Indu , Khuller G. K. 
Published: July 2002

ABSTRACTThe therapeutic efficacy of human neutrophil peptide 1 (HNP-1) against experimental tuberculosis in mice on the basis of numbers of CFU has been examined. Mice infected with 1.5 × 104CFU ofMycobacterium tuberculosisH37Rv and treated with different doses of HNP-1 injected subcutaneously exhibited significant clearance of bacilli from lungs, livers, and spleens. There were time- and dose-dependent decreases in the bacillary load in lungs, livers, and spleens of the HNP-1-treated animals compared to that in controls (untreated animals). These observations strongly suggest the therapeutic activity of HNP-1 against tuberculosis.
In Vitro Activities of the Novel Ketolide Telithromycin (HMR 3647) against Erythromycin-Resistant
Streptococcus
Species
Authors: Jalava Jari , Kataja Janne , Seppälä Helena , Huovinen Pentti 
Published: July 2002

ABSTRACT

The in vitro susceptibilities of 184 erythromycin-resistant streptococci to a novel ketolide, telithromycin (HMR 3647), were tested. These clinical isolates included 111
Streptococcus pyogenes
, 18 group C streptococcus, 18 group G streptococcus, and 37
Streptococcus pneumoniae
strains. The MICs for all but eight
S. pyogenes
strains were ≤0.5 μg/ml, indicating that telithromycin is active in vitro against erythromycin-resistant
Streptococcus
strains. All strains for which MICs were ≥1 μg/ml had an
erm
(B) resistance gene and six strains for which MICs were ≥4 μg/ml had a constitutive
erm
(B) gene (MIC range, 4 to 64 μg/ml). Interestingly, for
S. pneumoniae
strains with a constitutive
erm
(B) gene, MICs were ≤0.25 μg/ml (MIC range, ≤0.008 to 0.25 μg/ml). Our in vitro data show that for
S. pyogenes
strains which constitutively express the
erm
(B) methylase gene, MICs are so high that the strains might be clinically resistant to telithromycin.
Identification of Genes Induced by a Macrophage Activator, S-28463, Using Gene Expression Array Analysis
Authors: Buates Sureemas , Matlashewski Greg 
Published: July 2002

ABSTRACTS-28463 and imiquimod are imidazoquinoline compounds which stimulate microbicidal activity by inducing a local immune response at the site of application. Imiquimod-containing cream is an effective clinical treatment against cervical warts caused by human papillomavirus infection. Imiquimod also induces leishmanicidal activity both in vitro in macrophages and in vivo in a mouse model for cutaneous leishmaniasis. The major target cells of S-28463 and imiquimod are macrophages. To explore the molecular basis in which imidazoquinolines generate macrophage microbicidal activity, a cDNA gene array analysis was undertaken to identify genes induced by S-28463. Out of 588 genes screened in this assay, only 13 genes were significantly induced by S-28463. Remarkably, virtually all of the induced genes are involved in macrophage activation and inflammatory response. This experimental approach defines the mechanism of action of this clinically relevant compound in the induction of microbicidal activity in macrophages and also potentially identifies novel genes associated with microbicidal activity in this cell type.
N-Terminal Fatty Acid Substitution Increases the Leishmanicidal Activity of CA(1-7)M(2-9), a Cecropin-Melittin Hybrid Peptide
Authors: Chicharro Cristina , Granata Cesare , Lozano Rosario , Andreu David , Rivas Luis 
Published: July 2002

ABSTRACT

In order to improve the leishmanicidal activity of the synthetic cecropin A-melittin hybrid peptide CA(1-7)M(2-9) (KWKLFKKIGAVLKVL-NH
2
), a systematic study of its acylation with saturated linear fatty acids was carried out. Acylation of the N
ɛ
-7 lysine residue led to a drastic decrease in leishmanicidal activity, whereas acylation at lysine 1, in either the α or the ɛ NH
2
group, increased up to 3 times the activity of the peptide against promastigotes and increased up to 15 times the activity of the peptide against amastigotes. Leishmanicidal activity increased with the length of the fatty acid chain, reaching a maximum for the lauroyl analogue (12 carbons). According to the fast kinetics, dissipation of membrane potential, and parasite membrane permeability to the nucleic acid binding probe SYTOX green, the lethal mechanism was directly related to plasma membrane permeabilization.
SHV-16, a β-Lactamase with a Pentapeptide Duplication in the Omega Loop
Authors: Arpin Corinne , Labia Roger , Andre Catherine , Frigo Cécile , El Harrif Zoubida , Quentin Claudine 
Published: July 2002

ABSTRACTA clinical isolate ofKlebsiella pneumoniaewas found to be resistant to ampicillin (MIC of 128 μg/ml), ticarcillin (MIC of 512 μg/ml), and ceftazidime (MIC of 128 μg/ml) and susceptible to all other β-lactams; a synergistic effect between clavulanate and ceftazidime suggested the presence of an extended-spectrum β-lactamase (ESBL). Transconjugants inEscherichia coliwere obtained at low levels (10−7per donor cell) and exhibited a similar β-lactam resistance pattern (resistant to ampicillin, ticarcillin, and ceftazidime at 64 μg/ml). The ESBL, pI 7.6, was encoded by a large plasmid (>100 kb) which did not carry any other resistance determinant. The ESBL-encoding gene was amplified by PCR usingblaSHV-specific primers and was sequenced. The deduced amino acid sequence of the SHV-16 ESBL showed that it differed from SHV-1 by only a pentapeptide insertion (163DRWET167) corresponding to a tandem duplication in the omega loop. The implication of the 163a-DRWET163b-DRWET sequence in ceftazidime resistance was confirmed by cloning eitherblaSHV-1orblaSHV-16in the same vector, subsequently introduced in the sameE. colistrain. Under these isogenic conditions, SHV-16 conferred a 32-fold increase in ceftazidime MIC compared to that with SHV-1. Furthermore, site-directed mutagenesis experiments modifying either E166aA or E166bA revealed that the functional glutamic residue was that located in the first copy of the duplicated sequence. But surprisingly, the second E166b also conferred a low-level resistance to ceftazidime. This work is the first description of a class A enzyme exhibiting an extended substrate specificity due to an insertion instead of a nucleotide substitution(s) in a clinical isolate.
Expression of Ubiquitin Gene in
Microsporum canis
and
Trichophyton mentagrophytes
Cultured with Fluconazole
Authors: Kano Rui , Okabayashi Ken , Nakamura Yuka , Watanabe Shinichi , Hasegawa Atsuhiko 
Published: July 2002

ABSTRACT

The expression of the ubiquitin (Ub) gene in dermatophytes was examined for its relation to resistance against the antifungal drug fluconazole. The nucleotide sequences and the deduced amino acid sequences of the Ub gene in
Microsporum canis
were proven to be 99% similar to those of the Ub gene in
Trichophyton mentagrophytes
. Expression of mRNA of Ub in
M. canis
and
T. mentagrophytes
was enhanced when the fungi were cultured with fluconazole. The antifungal activity of fluconazole against these dermatophytes was increased in the presence of Ub proteasome inhibitor.
Diversity of Ribosomal Mutations Conferring Resistance to Macrolides, Clindamycin, Streptogramin, and Telithromycin in
Streptococcus pneumoniae
Authors: Canu Annie , Malbruny Brigitte , Coquemont Maëlle , Davies Todd A. , Appelbaum Peter C. , Leclercq Roland 
Published: July 2002

ABSTRACT

Mechanisms of resistance were studied in 22 macrolide-resistant mutants selected in vitro from 5 parental strains of macrolide-susceptible
Streptococcus pneumoniae
by serial passage in various macrolides (T. A. Davies, B. E. Dewasse, M. R. Jacobs, and P. C. Appelbaum, Antimicrob. Agents Chemother., 44:414–417, 2000). Portions of genes encoding ribosomal proteins L22 and L4 and 23S rRNA (domains II and V) were amplified by PCR and analyzed by single-strand conformational polymorphism analysis to screen for mutations. The DNA sequences of amplicons from mutants that differed from those of parental strains by their electrophoretic migration profiles were determined. In six mutants, point mutations were detected in the L22 gene (G95D, P99Q, A93E, P91S, and G83E). The only mutant selected by telithromycin (for which the MIC increased from 0.008 to 0.25 μg/ml) contained a combination of three mutations in the L22 gene (A93E, P91S, and G83E). L22 mutations were combined with an L4 mutation (G71R) in one strain and with a 23S rRNA mutation (C2611A) in another strain. Nine other strains selected by various macrolides had A2058G (
n
= 1), A2058U (
n
= 2), A2059G (
n
= 1), C2610U (
n
= 1), and C2611U (
n
= 4) mutations (
Escherichia coli
numbering) in domain V of 23S rRNA. One mutant selected by clarithromycin and resistant to all macrolides tested (MIC, >32 μg/ml) and telithromycin (MIC, 4 μg/ml) had a single base deletion (A752) in domain II. In six remaining mutants, no mutations in L22, L4, or 23S rRNA could be detected.
Efficacy of Monoclonal Antibodies against Defined Antigens for Passive Immunotherapy of Chronic Gastrointestinal Cryptosporidiosis
Authors: Riggs Michael W. , Schaefer Deborah A. , Kapil Sushila J. , Barley-Maloney Lise , Perryman Lance E. 
Published: July 2002

ABSTRACTCryptosporidium parvumis an important cause of diarrhea in humans and calves and can persistently infect immunocompromised hosts. Presently, there are no consistently effective parasite-specific drugs for cryptosporidiosis. We hypothesized that neutralizing monoclonal antibodies (MAbs) targeting the apical complex and surface antigens CSL, GP25-200, and P23 could passively immunize against cryptosporidiosis. We recently reported that a formulation of MAbs 3E2 (anti-CSL), 3H2 (anti-GP25-200), and 1E10 (anti-P23) provided significant additive prophylactic efficacy over that of the individual MAbs in neonatal ICR mice. In the present study, these MAbs were evaluated for therapeutic efficacy against persistent infection in adult gamma interferon-depleted SCID mice. 3E2 demonstrated the most significant and consistent therapeutic effect, reducing intestinal infection in two experiments. In one experiment, 3E2 plus 3H2 and 3E2 plus 3H2 plus 1E10 also significantly reduced infection; however, no significant increase in efficacy over 3E2 alone was apparent. The results indicate that anti-CSL MAb 3E2 has highly significant efficacy in reducing, but not eliminating, persistentC. parvuminfection.
High Prevalence of Oxacillin-Resistant
Staphylococcus aureus
Isolates from Hospitalized Patients in Asia-Pacific and South Africa: Results from SENTRY Antimicrobial Surveillance Program, 1998-1999
Authors: Bell Jan M. , Turnidge John D. 
Published: July 2002

ABSTRACT

As part of the SENTRY antimicrobial surveillance program, we examined the prevalence rates, types, and antibiograms of oxacillin-resistant
Staphylococcus aureus
from hospitalized patients from 17 institutions in eight countries in Asia-Pacific and South Africa (APAC). From April 1998 to December 1999, a total of 1,711 isolates of
S. aureus
(814 from blood, 392 from the respiratory tract, 467 from skin and skin structures, and 38 from urine) were collected from hospitalized patients within the APAC region. Multidrug-resistant oxacillin-resistant
S. aureus
(MORSA) isolates, defined as strains with three or more resistances to drug classes other than β-lactams, were the most common type of oxacillin-resistant
S. aureus
(ORSA). They were the most frequently identified pathogen in wound infections and were common in bloodstream and lower respiratory tract infections. In all contributing institutions combined, more than 45% (range, 4 to 74%) of
S. aureus
isolates were oxacillin resistant, and in six institutions, this rate exceeded 60%. MORSA accounted for 91.2% of all oxacillin-resistant isolates. Distinct resistance patterns predominated at various sites within the APAC region, suggesting the local evolution of resistant clones. Non-multidrug-resistant strains were frequent in one part of Australia. No vancomycin-intermediate strains were detected, and no strains were resistant to linezolid or quinupristin-dalfopristin. MORSA strains are a very common cause of infection in hospitalized patients in the APAC region.
Enhanced Inhibition of Orthopoxvirus Replication In Vitro by Alkoxyalkyl Esters of Cidofovir and Cyclic Cidofovir
Authors: Kern Earl R. , Hartline Caroll , Harden Emma , Keith Kathy , Rodriguez Natalie , Beadle James R. , Hostetler Karl Y. 
Published: July 2002

ABSTRACT

The nucleotide phosphonates cidofovir (CDV) and cyclic cidofovir (cCDV) are potent antiviral compounds when administered parenterally but are not well absorbed orally. These compounds have been reported to have activity against orthopoxvirus replication in vitro and in animal models when administered parenterally or by aerosol. To obtain better oral activity, we synthesized a novel series of analogs of CDV and cCDV by esterification with two long-chain alkoxyalkanols, 3-hexadecyloxy-1-propanol (HDP-CDV; HDP-cCDV) or 3-octadecyloxy-1-ethanol (ODE-CDV; ODE-cCDV). Their activities were evaluated and compared with those of CDV and cCDV in human foreskin fibroblast (HFF) cells infected with vaccinia virus (VV) or cowpox virus (CV) using a plaque reduction assay. The 50% effective concentrations (EC
50
s) against VV in HFF cells for CDV and cCDV were 46.2 and 50.6 μM compared with 0.84 and 3.8 μM for HDP-CDV and HDP-cCDV, respectively. The EC
50
s for ODE-CDV and ODE-cCDV were 0.20 and 1.1 μM, respectively. The HDP analogs were 57- and 13-fold more active than the parent nucleotides, whereas the ODE analogs were 231- and 46-fold more active than the unmodified CDV and cCDV. Similar results were obtained using CV. Cytotoxicity studies indicated that although the analogs were more toxic than the parent nucleotides, the selective index was increased by 4- to 13-fold. These results indicate that the alkoxyalkyl esters of CDV and cCDV have enhanced activity in vitro and need to be evaluated for their oral absorption and efficacy in animal models.
Emergence of Group A Streptococcus Strains with Different Mechanisms of Macrolide Resistance
Authors: Bingen Edouard , Leclercq Roland , Fitoussi Frédéric , Brahimi Naïma , Malbruny Brigitte , Deforche Dominique , Cohen Robert 
Published: July 2002

ABSTRACT

The mechanisms of resistance to macrolides in seven group A streptococcal (
Streptococcus pyogenes
) isolates that were the cause of pharyngitis in children who were unsuccessfully treated with azithromycin (10 mg/kg of body weight/day for 3 days) were evaluated. All posttreatment strains were found to be genetically related to the pretreatment isolates by random amplified polymorphism DNA analysis and pulsed-field gel electrophoresis. Two isolates had acquired either a
mef
(A) or an
erm
(B) gene, responsible for macrolide efflux and ribosomal modification, respectively. Three isolates displayed mutations in the gene encoding the L4 ribosomal protein that is part of the exit tunnel within the 50S subunit of the bacterial ribosome. In the two remaining posttreatment strains, the mechanisms of macrolide resistance could not be elucidated.
tcrB, a Gene Conferring Transferable Copper Resistance inEnterococcus faecium: Occurrence, Transferability, and Linkage to Macrolide and Glycopeptide Resistance
Authors: Hasman Henrik , Aarestrup Frank M. 
Published: July 2002

ABSTRACTA newly discovered gene, designatedtcrB, which is located on a conjugative plasmid conferring acquired copper resistance inEnterococcus faecium, was identified in an isolate from a pig. ThetcrBgene encodes a putative protein belonging to the CPx-type ATPase family with homology (46%) to the CopB protein fromEnterococcus hirae. ThetcrBgene was found inE. faeciumisolated from pigs (75%), broilers (34%), calves (16%), and humans (10%) but not in isolates from sheep. Resistant isolates, containing thetcrBgene, grew on brain heart infusion agar plates containing up to 28 mM CuSO4compared to only 4 mM for the susceptible isolates. Copper resistance, and therefore the presence of thetcrBgene, was strongly correlated to macrolide and glycopeptide resistance in isolates from pigs, and thetcrBgene was shown to be located on the same conjugative plasmid as the genes responsible for resistance to these two antimicrobial agents. The frequent occurrence of this new copper resistance gene in isolates from pigs, where copper sulfate is being used in large amounts as feed additive, suggests that the use of copper has selected for resistance.
Antisense Downregulation of ς
32
as a Transient Metabolic Controller in
Escherichia coli
: Effects on Yield of Active Organophosphorus Hydrolase
Authors: Srivastava Ranjan , Cha Hyung Joon , Peterson Marvin S. , Bentley William E. 
Published: July 2002

ABSTRACT

Plasmids containing an antisense fragment of the ς
32
gene were constructed and introduced into
Escherichia coli
cells. Downregulation of the ς
32
-mediated stress response was evaluated under heat shock and ethanol stress and during the production of organophosphorus hydrolase (OPH). Northern blot analyses revealed that ς
32
sense mRNA was virtually undetected in antisense-producing cultures from 5 to 20 min after antisense induction. However, lower-molecular-weight bands were found, presumably due to partial degradation of ς
32
mRNA. While a >10-fold increase in ς
32
protein level was found under ethanol stress in the control cultures, antisense producing cultures resulted in a <3-fold increase, indicating downregulation of ς
32
. Correspondingly, antisense synthesis resulted in a decreased level of a ς
32
regulated chaperone (GroEL) for the first 2 h after induction relative to control cultures without ς
32
antisense mRNA. The total yield of OPH in the presence of ς
32
antisense was, on average, 62% of the yield without antisense. However, during ς
32
antisense production, a sixfold-higher specific OPH activity was observed compared to non-antisense-producing cultures.
Structure and Species Composition of Mercury-Reducing Biofilms
Authors: Wagner-Döbler I. , Lünsdorf H. , Lübbehüsen T. , von Canstein H. F. , Li Y. 
Published: July 2002

ABSTRACT

Mercury-reducing biofilms from packed-bed bioreactors treating nonsterile industrial effluents were shown to consist of a monolayer of bacteria by scanning electron microscopy. Droplets of several micrometers in diameter which accumulated outside of the bacterial cells were identified as elemental mercury by electron-dispersive X-ray analysis. The monospecies biofilms of
Pseudomonas putida
Spi3 initially present were invaded by additional strains, which were identified to the species level by thermogradient gel electrophoresis (TGGE) and 16S rDNA sequencing. TGGE community fingerprints of the biofilms showed that they were composed of the effluent bacteria and did not contain uncultivable microorganisms. Of the 13 effluent bacterial strains, 2 were not mercury resistant, while all the others had resistance levels similar to or higher than the inoculant strain.
Limitation of Bacterial Growth by Dissolved Organic Matter and Iron in the Southern Ocean
Authors: Church Matthew J. , Hutchins David A. , Ducklow Hugh W. 
Published: July 2002

ABSTRACT

The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42°S and 55°S along 141°E. Bacterial abundance, mean cell volume, and [
3
H]thymidine and [
3
H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favorably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilization may be partly constrained by iron availability in the HNLC Southern Ocean.
A Selective Medium and a Specific Probe for Detection of
Vibrio vulnificus
Authors: Cerdà-Cuéllar Marta , Jofre Joan , Blanch Anicet R. 
Published: July 2002

ABSTRACT

A selective medium (VVM) and a specific 16S rRNA gene (rDNA) probe (V3VV) for the detection of
Vibrio vulnificus
were developed. The medium contains
d
-(+)-cellobiose as the main carbon source and electrolytes (MgCl
2
-6H
2
O and KCl), which stimulate bacterial growth. Polymyxin B, colistin, and moderate alkalinity and salinity provide selectivity properties.
V. vulnificus
grows on VVM as flat, bright yellow colonies. Other
Vibrio
species tested either did not grow or showed green-bluish colonies, with the exception of
V. campbelli
,
V. carchariae
, and
V. navarrensis
. There is a higher colony count on VVM agar than on cellobiose-colistin agar or on modified cellobiose-polymyxin B-colistin agar. The specific probe was evaluated by colony hybridization and dot blot hybridization with PCR-amplified 16S rDNA using collection strains and environmental isolates. No strain studied other than
V. vulnificus
showed positive hybridization with this oligonucleotide. The combined use of VVM agar and the V3VV probe provided the recovery of
V. vulnificus
from mixed bacterial suspensions and spiked mussels.