bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutations in
Bartonella bacilliformis gyrB
Confer Resistance to Coumermycin A
1
Authors: Battisti James M. , Smitherman Laura S. , Samuels D. Scott , Minnick Michael F.
Published: October 2018

This study describes the first isolation and characterization of spontaneous mutants conferring natural resistance to an antibiotic for any
Bartonella
species. The
Bartonella bacilliformis gyrB
gene, which encodes the B subunit of DNA gyrase, was cloned and sequenced. The
gyrB
open reading frame (ORF) is 2,079 bp and encodes a deduced amino acid sequence of 692 residues, corresponding to a predicted protein of ∼77.5 kDa. Sequence alignment indicates that
B. bacilliformis
GyrB is most similar to the GyrB protein from
Bacillus subtilis
(40.1% amino acid sequence identity) and that it contains the longest N-terminal tail (52 residues) of any GyrB characterized to date. The cloned
B. bacilliformis gyrB
was expressed in an
Escherichia coli
S30 cell extract and was able to functionally complement a temperature-sensitive
E. coli
Cou
r
gyrB
mutant (strain N4177). We isolated and characterized spontaneous mutants of
B. bacilliformis
resistant to coumermycin A
1
, an antibiotic that targets GyrB. Sequence analysis of
gyrB
from 12 Cou
r
mutants of
B. bacilliformis
identified single nucleotide transitions at three separate loci in the ORF. The predicted amino acid substitutions resulting from these transitions are Gly to Ser at position 124 (Gly124→Ser), Arg184→Gln, and Thr214→Ala or Thr214→Ile, which are analogous to mutated residues found in previously characterized resistant
gyrB
genes from
Borrelia burgdorferi
,
E. coli
,
Staphylococcus aureus
, and
Haloferax
sp. The Cou
r
mutants are three to five times more resistant to coumermycin A
1
than the wild-type parental strain.
Antimicrobial Susceptibility of Bacteria Isolated from Orthopedic Implants following Revision Hip Surgery
Authors: Tunney Michael M. , Ramage Gordon , Patrick Sheila , Nixon James R. , Murphy Philip G. , Gorman Sean P.
Published: October 2018

The susceptibilities of 49 isolates recovered from orthopedic implants to seven antimicrobial agents were evaluated by the broth microdilution method. Ciprofloxacin and vancomycin were more active than gentamicin, representing aminoglycosides which are routinely incorporated into bone cement, and also more active than the peroperative antimicrobial agents cefamandole and erythromycin. The use of ciprofloxacin and vancomycin in vivo, therefore, warrants further evaluation.
Human Immunodeficiency Virus Protease Inhibitors Serve as Substrates for Multidrug Transporter Proteins MDR1 and MRP1 but Retain Antiviral Efficacy in Cell Lines Expressing These Transporters
Authors: Srinivas Ranga V. , Middlemas David , Flynn Pat , Fridland Arnold
Published: October 2018

The human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs)—saquinavir, ritonavir, nelfinavir, and indinavir—interact with the ABC-type multidrug transporter proteins MDR1 and MRP1 in CEM T-lymphocytic cell lines. Calcein fluorescence was significantly enhanced in MDR1+CEM/VBL100 and MRP1+CEM/VM-1-5 cells incubated in the presence of various HIV PIs and calcein acetoxymethyl ester. HIV PIs also enhanced the cytotoxic activity of doxorubicin, a known substrate for MDR1 and MRP1, in both VBL100 and VM-1-5 CEM lines. Saquinavir, ritonavir, and nelfinavir enhanced doxorubicin toxicity in CEM/VBL100 cells by approximately three- to sevenfold. Saquinavir and ritonavir also enhanced doxorubicin toxicity in CEM/VM-1-5 cells. HIV-1 replication was effectively inhibited by the various PIs in all of the cell lines, and the 90% inhibitory concentration for a given compound was comparable between the different cell types. Therefore, overexpression of MDR1 or MRP1 by T lymphocytes is not likely to limit the antiviral efficacy of HIV PI therapy.
Expression of the
Pseudomonas aeruginosa
Gentamicin Resistance Gene
aacC3
in
Escherichia coli
Authors: van Boxtel Renée A. J. , van de Klundert Jos A. M.
Published: October 2018

The
Pseudomonas aeruginosa aacC3
gene was expressed in
Escherichia coli
after cloning of the single gene behind the strong
tac
promoter. In the original
Pseudomonas
strain,
aacC3
is preceded by
cysC
; together they form a single transcription unit. The ribosome-binding site and start codon of
aacC3
are involved in a putative intercistronic hairpin, the stability of which interfered with the aminoglycoside resistance level. In Northern blots, full-length transcripts comprising both
cysC
and
aacC3
could not be detected either in the original
Pseudomonas
strain or in
E. coli
harboring a plasmid with the cloned operon. In contrast,
cysC
transcripts were abundant. Cloning of the operon between the
tac
promoter and a transcription termination signal resulted in higher mRNA levels and phenotypic expression in
E. coli
. The absence of a transcription termination signal in the wild-type
cysC-aacC3
sequence is associated with transcripts of heterogeneous size that were undetected in Northern blots. Our results shed more light on the expression of this gentamicin resistance determinant, although the discrepancies between its expression in
E. coli
and
Pseudomonas
are not fully solved.
No Interaction between Ciprofloxacin and an Oral Contraceptive
Authors: Scholten P. C. , Droppert R. M. , Zwinkels M. G. J. , Moesker H. L. , Nauta J. J. P. , Hoepelman I. M.
Published: October 2018

Several antibiotics have been reported to lessen the ovarian suppression produced by oral contraceptive agents, as a result of drug interactions. The present investigation was designed to study the likelihood of the occurrence of any such interaction between the fluoroquinolone antibiotic ciprofloxacin (Ciproxin) at a dosage of 500 mg twice a day and the “low-dose” oral contraceptive Marvelon (30 μg of ethinyl estradiol [EE] plus 150 μg of desogestrel). Twenty-four healthy female volunteers were studied in a double-blind, placebo-controlled, randomized crossover trial. There were no significant differences between measurements of the area under the concentration-time curve of EE up to 24 h after oral contraceptive intake during placebo and ciprofloxacin administration on days 11 and 16 of the cycles, indicating the absence of pharmacokinetic interaction. Similarly, no clinically significant differences in the levels of sex hormone binding globulin were found between the placebo and ciprofloxacin cycles, indicating no major variation in EE levels during ciprofloxacin and placebo treatment. Ten subjects in each of the placebo and ciprofloxacin groups had early-follicular-phase levels of 17-β estradiol (<184 ng/liter) at one or more points during their cycles, but none had values above the early-follicular-phase range, indicating no significant ovarian activity. In addition, all subjects had progesterone levels of <2 ng/ml, indicating the absence of ovulation. Only two subjects, who received the placebo, had evidence of sustained follicular growth to a potentially ovulatory follicle (∼18 mm). We conclude that ciprofloxacin does not interfere with the ovarian suppression produced by the low-dose oral contraceptive Marvelon.
In Vitro and In Vivo Antibacterial Activities of CS-834, a New Oral Carbapenem
Authors: Yamaguchi Keizo , Domon Haruki , Miyazaki Shuichi , Tateda Kazuhiro , Ohno Akira , Ishii Kazuhiro , Matsumoto Tetsuya , Furuya Nobuhiko
Published: October 2018

CS-834 is a prodrug of the carbapenem R-95867, developed by Sankyo Co., Ltd., Tokyo, Japan. To investigate the possibility that CS-834 may be the first carbapenem usable in an oral dosage form, its in vitro antibacterial activity (as R-95867) and in vivo antibacterial activity were compared with those of cefpodoxime proxetil, cefditoren pivoxil, cefdinir, ofloxacin, imipenem, and amoxicillin. R-95867 had high levels of activity against methicillin-susceptible staphylococci and streptococci, including penicillin-resistant
Streptococcus pneumoniae
, as well as
Neisseria gonorrhoeae
,
Moraxella catarrhalis
, the members of the family
Enterobacteriaceae
(with the exception of
Serratia marcescens
),
Haemophilus influenzae
, and
Bordetella pertussis
; for all these strains, the MICs at which 90% of tested strains are inhibited (MIC
90
s) were 1.0 μg/ml or less. Against methicillin-resistant staphylococci, enterococci,
Serratia marcescens
,
Brukholderia cepacia
,
Stenotrophomonas maltophilia
, and
Acinetobacter calcoaceticus
, R-95867 showed activity comparable to or slightly less than that of imipenem, with MIC
90
s ranging from 2 to >128 μg/ml. The in vivo efficacy of oral CS-834 against experimental mouse septicemia caused by gram-positive and gram-negative bacteria was better than that of comparative drugs. In murine respiratory infection models, the efficacy of CS-834 reflected not only its potent in vitro activity but also the high levels present in the lungs.
Prevalence of Antimicrobial-Resistant Pathogens in Middle Ear Fluid: Multinational Study of 917 Children with Acute Otitis Media
Authors: Jacobs Michael R. , Dagan Ron , Appelbaum Peter C. , Burch Daniel J.
Published: October 2018

The management of acute otitis media is complicated by the emergence of resistance to β-lactam and other antibiotics among common pathogens. We conducted a large, international study of infants and children with acute otitis media to identify pathogens and susceptibility patterns. During the winter of 1994 to 1995, middle ear fluid samples were collected from 917 patients with acute otitis media in Bulgaria, the Czech Republic, Hungary, Romania, Slovakia, Israel, and the United States. A single reference laboratory performed in vitro susceptibility testing. Pathogens were isolated from 62% of the patients. For
Streptococcus pneumoniae
(30% of the patients), untypeable
Haemophilus influenzae
(17%), and
Moraxella catarrhalis
(4%), there was significant variation among geographic regions (
P
< 0.001). The composite susceptibilities of these three organisms to amoxicillin ranged from 62% in the United States to 89% in Eastern and Central Europe; the corresponding susceptibilities to amoxicillin-clavulanate ranged from 90% in Israel to 95% in Eastern and Central Europe. β-Lactamase was produced by 31 and 100% of the isolates of
H. influenzae
and
M. catarrhalis
, respectively. More isolates of
S. pneumoniae
were susceptible to amoxicillin (90%) or amoxicillin-clavulanate (90%) than to penicillin (70%;
P
= 0.002). The prevalence of resistant
S. pneumoniae
was highest in patients less than 12 months of age.
S. pneumoniae
,
H. influenzae
, and
M. catarrhalis
remain the most important bacterial pathogens in patients with acute otitis media; however, their prevalence is variable and resistance patterns are changing.
Susceptibilities of Penicillin- and Erythromycin-Susceptible and -Resistant Pneumococci to HMR 3647 (RU 66647), a New Ketolide, Compared with Susceptibilities to 17 Other Agents
Authors: Pankuch G. A. , Visalli M. A. , Jacobs M. R. , Appelbaum P. C.
Published: October 2018

Susceptibility of 230 penicillin- and erythromycin-susceptible and -resistant pneumococci to HMR 3647 (RU 66647), a new ketolide, was tested by agar dilution, and results were compared with those of erythromycin, azithromycin, clarithromycin, roxithromycin, rokitamycin, clindamycin, pristinamycin, ciprofloxacin, sparfloxacin, trimethoprim-sulfamethoxazole, doxycycline, chloramphenicol, cefuroxime, ceftriaxone, imipenem, and vancomycin. HMR 3647 was very active against all strains tested, with MICs at which 90% of the strains were inhibited (MIC
90
s) of 0.03 μg/ml for erythromycin-susceptible strains (MICs, ≤0.25 μg/ml) and 0.25 μg/ml for erythromycin-resistant strains (MICs, ≥1.0 μg/ml). All other macrolides yielded MIC
90
s of 0.03 to 0.25 and >64.0 μg/ml for erythromycin-susceptible and -resistant strains, respectively. The MICs of clindamycin for 51 of 100 (51%) erythromycin-resistant strains were ≤0.125 μg/ml. The MICs of pristinamycin for all strains were ≤1.0 μg/ml. The MIC
90
s of ciprofloxacin and sparfloxacin were 4.0 and 0.5 μg/ml, respectively, and were unaffected by penicillin or erythromycin susceptibility. Vancomycin and imipenem inhibited all strains at ≤1.0 μg/ml. The MICs of cefuroxime and cefotaxime rose with those of penicillin G. The MICs of trimethoprim-sulfamethoxazole, doxycycline, and chloramphenicol were variable but were generally higher in penicillin- and erythromycin-resistant strains. HMR 3647 had the best kill kinetics of all macrolides tested against 11 erythromycin-susceptible and -resistant strains, with uniform bactericidal activity (99.9% killing) after 24 h at two times the MIC and 99% killing of all strains at two times the MIC after 12 h for all strains. Pristinamycin showed more rapid killing at 2 to 6 h, with 99.9% killing of 10 of 11 strains after 24 h at two times the MIC. Other macrolides showed significant activity, relative to the MIC, against erythromycin-susceptible strains only.
Role of Superoxide in Catalase-Peroxidase-Mediated Isoniazid Action against Mycobacteria
Authors: Wang Jian-Ying , Burger Richard M. , Drlica Karl
Published: October 2018

Isoniazid (INH) activation in vitro is associated with reduction of the mycobacterial ferric KatG catalase-peroxidase by hydrazine and reaction with O
2
to form an oxyferrous enzyme complex. Since this complex could also form directly via reaction of ferric KatG with superoxide, intracellular activation might be responsive to superoxide concentration. When
Mycobacterium smegmatis
carrying the
M. bovis katG
gene was treated with nontoxic levels of plumbagin, a generator of superoxide, the bacteriostatic activity of INH increased unless a plasmid-borne superoxide dismutase gene was also present. Thus, endogenous superoxide probably contributes to intracellular activation of INH.
Zidovudine Pharmacokinetics in Premature Infants Exposed to Human Immunodeficiency Virus
Authors: Mirochnick Mark , Capparelli Edmund , Dankner Wayne , Sperling Rhoda S. , van Dyke Russ , Spector Stephen A.
Published: October 2018

We used population analysis techniques to determine zidovudine (ZDV) pharmacokinetic parameters in 15 preterm neonates (mean gestational age, 29.4 weeks; mean birth weight, 1,230 g) at a mean age of 5.5 days. The values of the pharmacokinetic parameters were as follows: clearance, 2.53 ± 0.44 ml/min/kg; volume of distribution, 1.59 ± 0.51 liters/kg; and half-life, 7.2 ± 1.5 h. For seven infants studied a second time, at a mean age of 17.7 days, an increase in the mean clearance (2.33 versus 4.35 ml/min/kg;
P
= 0.024) and a decrease in the half-life (7.3 versus 4.4 h;
P
= 0.003) were found. The ZDV clearance is low and the half-life is prolonged in premature neonates, but the clearance increases and the half-life decreases with postnatal age. Potentially toxic concentrations may accumulate in serum if the standard dosage for full-term infants is used. We suggest that initial ZDV dosing should be reduced to 1.5 mg every 12 h for preterm neonates.
Pharmacokinetics of Two Multiple-Dosing Regimens of D0870 in Human Immunodeficiency Virus-Positive Patients: a Phase I Study
Authors: De Wit S. , O’Doherty E. , Edwards J. , Yates R. , Smith R. P. , Clumeck A. N.
Published: October 2018

D0870 is a triazole with a broad antifungal spectrum, and it has been shown to have both in vitro and in vivo activities against wild-type and fluconazole-resistant strains of
Candida albicans
. Twenty-two human immunodeficiency virus (HIV)-positive male subjects were enrolled in an open, nonrandomized trial investigating the pharmacokinetics of two different dosing regimens of D0870 and assessing the safety of multiple oral doses of D0870 in HIV-positive subjects and their ability to tolerate multiple oral doses. Nine subjects received an initial loading dose of 50 mg, followed by four once-daily maintenance doses of 10 mg. A further nine subjects received an initial 200-mg loading dose followed by four daily maintenance doses of 25 mg. All subjects were fasting. A single loading dose of 50 mg of D0870 resulted in a mean maximum concentration in serum (
C
max
) of 107 ± 32 ng/ml. Concentrations in plasma were maintained by the 10-mg once-daily dosing regimen as seen by the similar values of the area under the concentration-time curve from 0 to 24 h following dosing on days 1 and 5 and a mean accumulation ratio close to unity (0.90). The terminal plasma half-life of D0870 in plasma following dosing on day 5 ranged from 23 to 85 h (mean, 49 h). A single loading dose of 200 mg of D0870 resulted in a
C
max
of 431 ± 186 ng/ml. Concentrations in plasma were again maintained by the 25-mg daily dosing regimen, with the mean accumulation ratio being close to unity (1.17). The terminal half-life of D0870 in plasma following dosing on day 5 of phase II of the study ranged from 34 to 137 h (mean, 71 h). In addition, the concentrations achieved in the plasma of these HIV-positive subjects were similar to the values predicted from simulations based on data derived from normal, healthy subjects. D0870 was well tolerated. No serious adverse events were experienced during the course of the study, and all volunteers completed the trial. A total of 15 adverse events were reported, but none were considered to be related to the administration of D0870 and all had resolved by the end of the trial. No changes in the hematology, clinical chemistry, or urinalysis parameters were considered to be related to dosing with D0870. No clinically significant changes in the electrocardiogram parameters were noted during the trial. The data generated in this trial support further investigation of these regimens with HIV-positive subjects with fluconazole-susceptible or -resistant oropharyngeal candidosis.
Efficacy of LY333328 against Experimental Methicillin-Resistant
Staphylococcus aureus
Endocarditis
Authors: Kaatz Glenn W. , Seo Susan M. , Aeschlimann Jeffrey R. , Houlihan Heather H. , Mercier Renee-Claude , Rybak Michael J.
Published: October 2018

The in vivo efficacy of LY333328, a new glycopeptide antibiotic, was compared with that of vancomycin by using the rabbit model of left-sided methicillin-resistant
Staphylococcus aureus
endocarditis. Animals received LY333328 or vancomycin (25 mg/kg of body weight every 24 or 8 h, respectively) for 4 days. These drugs were equally effective in clearing bacteremia and in reducing bacterial counts in vegetations and tissues. We conclude that in this model, LY333328 was microbiologically effective and may be a therapeutic alternative to vancomycin.
In Vitro Activities of Terbinafine against Cutaneous Isolates ofCandida albicansand Other Pathogenic Yeasts
Authors: Ryder Neil S. , Wagner Sonja , Leitner Ingrid
Published: October 2018

Terbinafine is active in vitro against a wide range of pathogenic fungi, including dermatophytes, molds, dimorphic fungi, and some yeasts, but earlier studies indicated that the drug had little activity againstCandida albicans. In contrast, clinical studies have shown topical and oral terbinafine to be active in cutaneous candidiasis andCandidanail infections. In order to define the anti-Candidaactivity of terbinafine, we tested the drug against 350 fresh clinical isolates and additional strains by using a broth dilution assay standardized according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS) M27-A assay. Terbinafine was found to have an MIC of 1 μg/ml for referenceC. albicansstrains. For 259 clinical isolates, the MIC at which 50% of the isolates are inhibited (MIC50) of terbinafine was 1 μg/ml (fluconazole, 0.5 μg/ml), and the MIC90was 4 μg/ml (fluconazole, 1 μg/ml). Terbinafine was highly active againstCandida parapsilosis(MIC90, 0.125 μg/ml) and showed potentially interesting activity against isolates ofCandida dubliniensis,Candida guilliermondii,Candida humicola, andCandida lusitaniae. It was not active against theCandida glabrata,Candida krusei, andCandida tropicalisisolates in this assay.Cryptococcus laurentiiandCryptococcus neoformanswere highly susceptible to terbinafine, with MICs of 0.06 to 0.25 μg/ml. The NCCLS macrodilution assay provides reproducible in vitro data for terbinafine againstCandidaand other yeasts. The MICs forC. albicansandC. parapsilosisare compatible with the known clinical efficacy of terbinafine in cutaneous infections, while the clinical relevance of its activities against the other species has yet to be determined.
Activities of HMR 3004 (RU 64004) and HMR 3647 (RU 66647) Compared to Those of Erythromycin, Azithromycin, Clarithromycin, Roxithromycin, and Eight Other Antimicrobial Agents against Unusual Aerobic and Anaerobic Human and Animal Bite Pathogens Isolated from Skin and Soft Tissue Infections in Humans
Authors: Goldstein Ellie J. C. , Citron Diane M. , Gerardo Sharon Hunt , Hudspeth Marie , Merriam C. Vreni
Published: October 2018

The activities of HMR 3004 and HMR 3647 and comparator agents, especially macrolides, were determined by the agar dilution method against 262 aerobic and 120 anaerobic strains isolated from skin and soft tissue infections associated with human and animal bite wounds. HMR 3004 and HMR 3647 were active against almost all aerobic and fastidious facultative isolates (MIC at which 90% of the isolates are inhibited [MIC
90
], ≤0.5 and 1 μg/ml, respectively) and against all anaerobes [
Bacteroides tectum
,
Porphyromonas macacae
(
salivosa
),
Prevotella heparinolytica
,
Porphyromonas
sp.,
Prevotella
sp., and peptostreptococci] at ≤0.25 and ≤0.5 μg/ml, respectively, except
Fusobacterium nucleatum
(HMR 3004, MIC
90
= 16 μg/ml; HMR 3647, MIC
90
= 8 μg/ml) and other
Fusobacterium
species (MIC
90
, 1 and 2 μg/ml, respectively). In general, HMR 3004 and HMR 3647 were more active than any of the macrolides tested. Azithromycin was more active than clarithromycin against all
Pasteurella
species, including
Pasteurella multocida
subsp.
multocida
,
Eikenella corrodens
, and
Fusobacterium
species, while clarithromycin was more active than azithromycin against
Corynebacterium
species,
Weeksella zoohelcum
,
B. tectum
, and
P. heparinolytica.
Mechanism of Resistance to Amikacin and Kanamycin in
Mycobacterium tuberculosis
Authors: Alangaden George J. , Kreiswirth Barry N. , Aouad Arlette , Khetarpal Minoo , Igno Felicitas R. , Moghazeh Soraya L. , Manavathu Elias K. , Lerner Stephen A.
Published: October 2018

An A1400G mutation of the
rrs
gene was identified in
Mycobacterium tuberculosis
(MTB) strain ATCC 35827 and in 13 MTB clinical isolates resistant to amikacin-kanamycin (MICs, >128 μg/ml). High-level cross-resistance may result from such a mutation since MTB has a single copy of the
rrs
gene. Another mechanism(s) may account for high-level amikacin-kanamycin resistance in two mutants and lower levels of resistance in four clinical isolates, all lacking the A1400G mutation.
Comparative Dispositions of Ofloxacin in Human Head, Axillary, and Pubic Hairs
Authors: Kosuge Kazuhiro , Uematsu Toshihiko , Araki Sei-Ichi , Matsuno Hiroyuki , Ohashi Kyoichi , Nakashima Mitsuyoshi
Published: October 2018

The distribution of ofloxacin (OFLX) along the shaft of each of three hair types, i.e., head, axillary and pubic, was investigated and compared among five healthy male volunteers 1 to 4 months after ingestion of OFLX for 1 or 2 days (total dose, 200 or 600 mg). Five strands of each hair type were sectioned together into successive 0.5-cm lengths starting from the dermal end, over a length of ≤6 cm, and the OFLX concentration in each hair section was measured by high-pressure liquid chromatography with fluorescence detection. The distribution of OFLX along the head hair shaft was narrow, having a single peak even 3 to 4 months after administration, suggesting a rather uniform growth rate among hair strands. On the other hand, the OFLX distribution along axillary or pubic hair shafts tended to be broad, even having two apparent peaks, and the growth rate did not seem uniform. Since axillary hair seemed to stop growing after having gained a length of ≤4 to 5 cm, it was suggested to enter a resting stage after the growth of ≤3 cm over the 2 to 4 months after OFLX incorporation. These findings indicate that head hair is the most suitable for analysis of individual drug use and the larger growth rate and cycle stage variabilities of strands of the other types of hair should be taken into account.
Pregnancy Outcome Following Gestational Exposure to Fluoroquinolones: a Multicenter Prospective Controlled Study
Authors: Loebstein Ronen , Addis Antonio , Ho Elaine , Andreou Roseann , Sage Suzanne , Donnenfeld Alan E. , Schick Betsy , Bonati Maurizio , Moretti Myla , Lalkin Arieh , Pastuszak Anne , Koren Gideon
Published: October 2018

Concerns regarding the teratogenicity of fluoroquinolones have resulted in their restricted use during gestation. This is despite an increasing need for their use due to emerging bacterial resistance. The objectives of the present investigation were to evaluate pregnancy and fetal outcomes following maternal exposure to fluoroquinolones and to examine whether in utero exposure to quinolones is associated with clinically significant musculoskeletal dysfunctions. We prospectively enrolled and followed up 200 women exposed to fluoroquinolones (norfloxacin, ciprofloxacin, ofloxacin) during gestation. Pregnancy outcome was compared with that for 200 controls matched for age and for smoking and alcohol consumption habits. Controls were exposed to nonteratogenic, nonembryotoxic antimicrobial agents matched by indication, duration of therapy (±3 days), and trimester of exposure. Rates of major congenital malformations did not differ between the group exposed to quinolones in the first trimester (2.2%) and the control group (2.6%) (relative risk, 0.85; 95% confidence interval, 0.21 to 3.49). Women treated with quinolones had a tendency for an increased rate of therapeutic abortions compared with the rate among women exposed to nonteratogens (relative risk, 4.50; 95% confidence interval, 0.98 to 20.57), resulting in lower live-birth rates (86 versus 94%;
P
= 0.02). The rates of spontaneous abortions, fetal distress, and prematurity and the birth weight did not differ between the groups. Gross motor developmental milestone achievements did not differ between the children of the mothers in the two groups. We concluded that the use of fluoroquinolones during embryogenesis is not associated with an increased risk of major malformations. There were no clinically significant musculoskeletal dysfunctions in children exposed to fluoroquinolones in utero. The higher rate of therapeutic abortions observed in quinolone-exposed women compared to that for their controls may be secondary to the misperception of a major risk related to quinolone use during pregnancy.
Lysostaphin Treatment of Experimental Methicillin-Resistant
Staphylococcus aureus
Aortic Valve Endocarditis
Authors: Climo Michael W. , Patron Roberto L. , Goldstein Beth P. , Archer Gordon L.
Published: October 2018

The emergence of clinical isolates of methicillin-resistant
Staphylococcus aureus
with reduced susceptibility to vancomycin has prompted a search for new and novel therapeutic agents active against
S. aureus
. Lysostaphin, a peptidase produced by
Staphylococcus simulans
, specifically cleaves the glycine-glycine bonds unique to the interpeptide cross-bridge of the
S. aureus
cell wall. The effectiveness of various regimens of dosing with intravenous lysostaphin was compared to that of vancomycin in the rabbit model of aortic valve endocarditis caused by a clinical methicillin-resistant
S. aureus
isolate. All animals were treated for a total of 3 days. The most active regimen, lysostaphin given three times daily, produced sterile vegetations in 10 of 11 treated rabbits, with a mean reduction in vegetation bacterial counts of 8.5 log
10
CFU/g compared to the counts in the untreated controls. In contrast, vancomycin given twice daily sterilized no vegetations and reduced vegetation bacterial counts by only 4.8 log
10
CFU/g. Lysostaphin given once daily was less effective, reducing mean vegetation bacterial counts by only 3.6 log
10
CFU/g, but the combination of lysostaphin once daily and vancomycin twice daily reduced the mean vegetation bacterial density by 7.5 log
10
CFU/g, a result that was significantly better than that for either regimen alone (
P
< 0.05). Lysostaphin was well tolerated by the rabbits, with no evidence of immunological reactions following up to 9 weeks of intravenous administration. We conclude that lysostaphin given alone or in combination with vancomycin is more effective in the treatment of experimental methicillin-resistant
S. aureus
aortic valve endocarditis than vancomycin alone.
Initial Concentration-Time Profile of Gentamicin Determines Efficacy against
Enterobacter cloacae
ATCC 13047
Authors: Rayner Craig R. , Ioannides-Demos Lisa L. , Brien Jo-Anne E. , Liolios Lisa L. , Spicer W. John
Published: October 2018

In vitro studies were designed to investigate the influence of peak drug concentration (
C
max
), the area under the concentration-time curve (AUC), and, consequently, the trough concentration on the bactericidal effects of gentamicin against
Enterobacter cloacae
(MIC, 0.5 mg/liter) by simulating bolus versus infusion administration and bolus dosing with altered drug clearance. Bacteria in the lag phase were exposed to gentamicin concentration-time profiles modelling either bolus or infusion dosing (AUC constant,
C
max
changing) with 30-min postdose peak concentrations (
C
peak30
) of 4, 6, 8, and 10 mg/liter or bolus dosing with normal and double drug clearance (
C
max
constant, AUC changing) corresponding to normal clearance profiles with
C
peak30
of 6 and 8 mg/liter. Exposure to gentamicin caused early bactericidal effects apparent by 2 h, followed by variable bacteriostatic and recovery phases. Exposure to bolus profiles resulted in greater bactericidal activity than the corresponding infusion profile up to a
C
peak30
of 8 mg/liter. At a
C
peak30
of 10 mg/liter, there were no differences in bactericidal effect. Double clearance profiles had a reduced bactericidal effect at 6 mg/liter compared to the corresponding normal clearance profile, but no differences in bactericidal effect were observed for 8-mg/liter double and normal clearance profiles. These results suggest that the initial exposure (i.e., 0 to 30 min) is a more important determinant for bacterial killing than the AUC or trough concentration for this bacterium. Subject to confirmation of these findings with other gram-negative bacteria, to optimize aminoglycoside efficacy the initial exposure (
C
max
) should be maximized by giving higher doses or bolus administration at intervals which may not produce detectable trough concentrations. Clinical trials with a broad range of patients, especially those with higher clearance, would confirm these in vitro observations and define optimal dosing recommendations.
Oral Antimicrobial Prophylaxis in Bone Marrow Transplant Recipients: Randomized Trial of Ciprofloxacin versus Ciprofloxacin-Vancomycin
Authors: Ford Clyde D. , Reilly William , Wood John , Classen David C. , Burke John P.
Published: October 2018

The optimal oral antimicrobial prophylactic regimen for bone marrow transplant recipients remains to be elucidated. We randomized 84 patients to receive either oral ciprofloxacin or ciprofloxacin plus vancomycin at hospital admission. Patients were monitored for bacteremias and clinical parameters, and stool and throat swab surveillance cultures were performed. The addition of vancomycin resulted in a significant decrease in the frequency of patients with surveillance cultures positive for coagulase-negative staphylococci (stool cultures, 44 versus 23%; throat swab cultures, 37 versus 19%) and alpha-hemolytic streptococci (throat swab cultures, 90 versus 60%). The frequencies of positivity for
Candida
spp. and gram-negative organisms on surveillance cultures were comparable. Despite these results, no differences in the incidences of bacteremias (12 of 41 versus 12 of 43 patients) or clinical parameters such as number of days to first fever, total number of febrile days, length of stay, and number of transfusions could be demonstrated. Because of a lack of efficacy of vancomycin and emerging problems with vancomycin-resistant isolates, vancomycin should not be used in oral antimicrobial prophylaxis regimens.
Postantibiotic Effect of Trovafloxacin against Gram-Positive and -Negative Organisms
Authors: Pankuch G. A. , Jacobs M. R. , Appelbaum P. C.
Published: October 2018

Trovafloxacin pneumococcal and staphylococcal postantibiotic effects (PAEs) were 0.7 to 1.8 and 0.7 to 2.4 h, respectively. For
Escherichia coli
and
Pseudomonas aeruginosa
, PAEs were 2.4 to 4.4 h. Pneumococcal and staphylococcal postantibiotic sub-MIC effects (PA-SMEs) (0.4 times the MIC) were 2.3 to 3.7 and 2.4 to >9.2 h, respectively, and
E. coli
PA-SMEs (0.3 times the MIC) were 6.8 to >12.0 h. For one
P. aeruginosa
strain, the PA-SME (0.4 times the MIC) was >10 h; in the other, rapid bactericidal activity precluded measurement.
Characterization of the 6′-
N
-Aminoglycoside Acetyltransferase Gene
aac(6′)-Iq
from the Integron of a Natural Multiresistance Plasmid
Authors: Centrón Daniela , Roy Paul H.
Published: October 2018

The nucleotide sequence of a newly identified amikacin resistance gene,
aac(6′)-Iq
(551 bp), is reported. It has 68.4 and 94.4% homology with the
aac(6′)-Ia
gene and the recently described
aac(6′)-Ip
gene, respectively. Analysis of its flanking sequences indicated that it is in the first cassette of a class I integron and has an
attC
site (59-base element) 108 bp in length.
Erythromycin Inhibits Tumor Necrosis Factor Alpha and Interleukin 6 Production Induced by Heat-KilledStreptococcus pneumoniaein Whole Blood
Authors: Schultz Marc J. , Speelman Peter , Zaat Sebastian , van Deventer Sander J. H. , van der Poll Tom
Published: October 2018

To determine the effects of penicillin and erythromycin on cytokine production induced by heat-killedStreptococcus pneumoniae(HKSP), we studied the effects of those drugs on cytokine production induced byS. pneumoniaein human whole blood in vitro and ex vivo. In whole blood in vitro, erythromycin, but not penicillin, caused a dose-dependent decrease in HKSP-induced production of tumor necrosis factor alpha (TNF) and interleukin 6 (IL-6), while the production of IL-10, IL-12, and gamma interferon was inhibited only at the highest erythromycin concentration tested (10−3M). The production of TNF and IL-6 in whole blood obtained from healthy subjects after a 30-min infusion of erythromycin (1,000 mg) was lower after ex vivo stimulation with HKSP than that in blood drawn before the infusion. Inhibition of TNF contributed to erythromycin-induced inhibition of IL-6 synthesis. Inhibition of TNF and IL-6 production by erythromycin may have a negative impact on host defense mechanisms during pneumococcal pneumonia.
Administration of Liposomal Agents and Blood Clearance Capacity of the Mononuclear Phagocyte System
Authors: van Etten Els W. M. , ten Kate Marian T. , Snijders Susan V. , Bakker-Woudenberg Irma A. J. M.
Published: October 2018

As liposomes are cleared from the circulation to a substantial extent by the phagocytic cells of the mononuclear phagocyte system (MPS), there is a question whether administration of liposome-based therapeutic agents interferes with clearance of infectious organisms by the MPS from blood. In the present study, at first the effect of administration of three types of empty liposomes (devoid of drug), differing in blood residence time, on carbon clearance and bacterial clearance from blood was studied with mice. Classical liposomes (LIP A) and placebo liposomes with lipid composition as in AmBisome (LIP B) or as in Doxil (LIP C) were used. Liposomes were administered intravenously as a single dose. Second, the effect of multiple-dose administration of AmBisome on bacterial blood clearance was studied with rats. AmBisome was administered with two different dosage schedules. The blood clearance capacity of the MPS was monitored at different time points after the last liposome injection. It was shown that the carbon blood clearance capacity of the MPS was impaired only at a high lipid dose of empty classical liposomes. The bacterial blood clearance capacity was never impaired, not even after prolonged treatment with AmBisome administered in a clinically relevant regimen.
Fluconazole Resistance Associated with Drug Efflux and Increased Transcription of a Drug Transporter Gene,
PDH1
, in
Candida glabrata
Authors: Miyazaki Haruko , Miyazaki Yoshitsugu , Geber Antonia , Parkinson Tanya , Hitchcock Christopher , Falconer Derek J. , Ward Douglas J. , Marsden Katherine , Bennett John E.
Published: October 2018

Sequential
Candida glabrata
isolates were obtained from the mouth of a patient infected with human immunodeficiency virus type 1 who was receiving high doses of fluconazole for oropharyngeal thrush. Fluconazole-susceptible colonies were replaced by resistant colonies that exhibited both increased fluconazole efflux and increased transcripts of a gene which codes for a protein with 72.5% identity to Pdr5p, an ABC multidrug transporter in
Saccharomyces cerevisiae
. The deduced protein had a molecular mass of 175 kDa and was composed of two homologous halves, each with six putative transmembrane domains and highly conserved sequences of ATP-binding domains. When the earliest and most azole-susceptible isolate of
C. glabrata
from this patient was exposed to fluconazole, increased transcripts of the
PDR5
homolog appeared, linking azole exposure to regulation of this gene.
Effect of Trovafloxacin on Production of Cytokines by Human Monocytes
Authors: Khan Anis A. , Slifer Teri R. , Remington Jack S.
Published: October 2018

Antibiotics have previously been shown to have immunomodulatory effects. We examined the effect of the broad-spectrum fluoroquinoline antibiotic trovafloxacin on cytokine synthesis by monocytes obtained from healthy human volunteers and stimulated with either lipopolysaccharide or gram-positive cells (heat-killedStaphylococcus aureus[Pansorbin]). Trovafloxacin levels achievable in humans suppressed in vitro synthesis of each of the cytokines analyzed, viz., interleukin-1α (IL-1α), IL-1β, IL-6, IL-10, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor alpha. This effect was not due to direct effects of the drug on cellular viability; at these concentrations, trovafloxacin did not have demonstrable cytotoxicity for the monocytes, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Although similar patterns of suppression of cytokine synthesis were observed in samples obtained from the same volunteers on different days, there were significant day-to-day variations. These results reveal that trovafloxacin possesses significant immunomodulatory activity in vitro and suggest that suppression of acute-phase inflammatory responses may occur in vivo, elicited through trovafloxacin’s effect on cytokine synthesis by human monocytes.
Efficacy of NS-718, a Novel Lipid Nanosphere-Encapsulated Amphotericin B, against
Cryptococcus neoformans
Authors: Hossain Mohammad Ashraf , Maesaki Shigefumi , Kakeya Hiroshi , Noda Tetsuhiro , Yanagihara Katsunori , Sasaki Eisuke , Hirakata Yoichi , Tomono Kazunori , Tashiro Takayoshi , Kohno Shigeru
Published: October 2018

In vitro and in vivo efficacies of NS-718, a lipid nanosphere-encapsulated amphotericin B (AMPH-B), have been studied. Of the tested AMPH-B formulations, NS-718 had the lowest MIC for
Cryptococcus neoformans
. In a murine model, low-dose therapy (0.8 mg/kg of body weight) with NS-718 showed higher efficacy than that with AmBisome. High-dose therapy (2.0 mg/kg) with NS-718 was much more effective than those with Fungizone and AmBisome. In mice treated with a high dose of NS-718, only a few yeast cells had grown in lung by 7 days after inoculation. A pharmacokinetic study showed higher concentrations of AMPH-B in lung following administration of NS-718 than after administration of AmBisome. Our results indicated that NS-718, a new AMPH-B formulation, is a promising antifungal agent for treatment of pulmonary cryptococcosis and could be the most effective antifungal agent against
C. neoformans
infections.
NorM, a Putative Multidrug Efflux Protein, of
Vibrio parahaemolyticus
and Its Homolog in
Escherichia coli
Authors: Morita Yuji , Kodama Kazuyo , Shiota Sumiko , Mine Tomoyuki , Kataoka Atsuko , Mizushima Tohru , Tsuchiya Tomofusa
Published: October 2018

We found that cells of
Vibrio parahaemolyticus
possess an energy-dependent efflux system for norfloxacin. We cloned a gene for a putative norfloxacin efflux protein from the chromosomal DNA of
V. parahaemolyticus
by using an
Escherichia coli
mutant lacking the major multidrug efflux system AcrAB as the host and sequenced the gene (
norM
). Cells of
E. coli
transformed with a plasmid carrying the
norM
gene showed elevated energy-dependent efflux of norfloxacin. The transformants showed elevated resistance not only to norfloxacin and ciprofloxacin but also to the structurally unrelated compounds ethidium, kanamycin, and streptomycin. These results suggest that this is a multidrug efflux system. The hydropathy pattern of the deduced amino acid sequence of NorM suggested the presence of 12 transmembrane domains. The deduced primary structure of NorM showed 57% identity and 88% similarity with that of a hypothetical
E. coli
membrane protein, YdhE. No reported drug efflux protein in the sequence databases showed significant sequence similarity with NorM. Thus, NorM seems to be a novel type of multidrug efflux protein. We cloned the
ydhE
gene from
E. coli
. Cells of
E. coli
transformed with the cloned
ydhE
gene showed elevated resistance to norfloxacin, ciprofloxacin, acriflavine, and tetraphenylphosphonium ion, but not to ethidium, when MICs were measured. Thus, it seems that NorM and YdhE differ somehow in substrate specificity.
Efficacy of Trovafloxacin, a New Quinolone Antibiotic, in Experimental Staphylococcal Endocarditis Due to Oxacillin-Resistant Strains
Authors: Bayer Arnold S. , Li Cong , Ing Michael
Published: October 2018

Therapeutic options for severe infections caused by strains of oxacillin-resistant
Staphylococcus aureus
(ORSA) and coagulase-negative staphylococci (ORSE) are very limited. With the increasing resistance of such strains to aminoglycosides, rifampin, and currently available quinolone agents, as well as the recent documentation of increasing resistance of ORSA to vancomycin (VANCO), new treatment alternatives are imperative. The in vivo efficacy of trovafloxacin (TROVA), a new quinolone agent with excellent antistaphylococcal activity in vitro, against experimental endocarditis (IE) due to β-lactamase-producing ORSA and ORSE strains (ORSA and ORSE IE) was evaluated. TROVA (25 mg/kg of body weight intravenously [i.v.] twice daily [b.i.d.]) was compared to VANCO (20 mg/kg i.v. b.i.d.) and two regimens of ampicillin-sulbactam (AMP-SUL; 200 mg/kg intramuscularly [i.m.] three times a day [t.i.d.] and 20 mg/kg i.m. b.i.d.), with all agents given for 3 or 6 days. AMP-SUL was included as a comparative treatment regimen because of its proven efficacy against experimental ORSA and ORSE IE. For both ORSA and ORSE IE, TROVA, AMP-SUL, and VANCO each reduced staphylococcal densities in vegetations compared to untreated controls (
P
< 0.01). For ORSA IE, TROVA was the most rapidly bactericidal agent—although not to a statistically significant degree—correlating with its superior bactericidal effect in vitro compared to those of VANCO and AMP-SUL.
Interactions between HMR 3647, a New Ketolide, and Human Polymorphonuclear Neutrophils
Authors: Vazifeh D. , Preira A. , Bryskier A. , Labro M. T.
Published: October 2018

HMR 3647, a new ketolide, is active upon intracellular pathogens. We previously demonstrated that HMR 3004 (RU 64004), another ketolide, is highly concentrated by human polymorphonuclear neutrophils (PMNs). This prompted us to evaluate whether the presence of a 3-keto group instead of anl-cladinose, a neutral sugar characteristic of erythromycin A derivatives, confers peculiar pharmacokinetic properties with regard to cellular accumulation and efflux. After incubation with the radiolabelled drug, HMR 3647 uptake was determined by a velocity gradient centrifugation technique. HMR 3647 was avidly concentrated by PMNs, without saturation, over a 3-h incubation period, with cellular-to-extracellular concentration ratios of 31 ± 4.2 at 5 min and up to 348 ± 27.1 at 180 min. About 60% of HMR 3647 was located in the granular compartment; less than 6% was associated with the membranes. HMR 3647 gradually egressed from loaded cells placed in drug-free medium. Uptake was dependent on environmental temperature (activation energy, 128 ± 9.4 kJ/mol) but not on extracellular pH. HMR 3647 displayed Michaelis-Menten saturation kinetics with a meanVmax of 2315 ng/2.5 × 106PMNs/5 min and a meanKmof 117 mg/liter (144 μM). As already observed with erythromycin A-derived macrolides, extracellular Ca2+was necessary for optimal uptake of HMR 3647. Interestingly, verapamil increased the uptake of HMR 3647 at 5 min, but this was followed by gradual inhibition at later incubation times, a phenomenon probably related to stimulation of drug efflux. The impact of intracellular accumulation of HMR 3647 on PMN functions was also investigated. In contrast to other erythromycin A derivatives, HMR 3647 only weakly triggered granule exocytosis, but it inhibited superoxide anion production in a time- and concentration-dependent manner, with concentrations which inhibited 50% of control response of 55 (67 μM) (5 min) and 30 (36 μM) (30 min) mg/liter for formyl-methionyl-leucyl-phenylalanine stimulation and 117 (143 μM) (5 min) and 44 (54 μM) (30 min) mg/liter for phorbol myristate acetate stimulation.
In Vitro Activities of Oral β-Lactams at Concentrations Achieved in Humans against Penicillin-Susceptible and -Resistant Pneumococci and Potential to Select Resistance
Authors: Thorburn Christine E. , Knott Sarah J. , Edwards David I.
Published: October 2018

The β-lactam susceptibilities of 65 strains of
Streptococcus pneumoniae
for which penicillin MICs covered a broad range were assessed. The order of potency was amoxicillin (AMX) = amoxicillin-clavulanate (AMC) > penicillin G > cefpodoxime (CPO) > cefuroxime (CXM) > cefprozil > cefaclor > loracarbef > cefixime. No decrease in susceptibility was seen following repeated subculture of two penicillin-susceptible strains of
S. pneumoniae
in AMX, AMC, cefaclor, or loracarbef, whereas repeated exposure to CPO and CXM resulted in 4- to 32-fold decreases in susceptibility for both strains. When one of these strains was exposed to concentrations of CPO, CXM, AMX, and AMC achieved in the serum of humans following the administration of an oral dose, all agents were rapidly bactericidal, with no decrease in susceptibility up to 72 h. This was consistent with antibiotic concentrations exceeding the MICs for 100% of the dosing interval. For a penicillin-resistant strain, MICs were exceeded for 29% of the 12-h dosing interval for 500 mg of AMX, 42% of the interval for AMC with 875 mg of AMX and 125 mg of clavulanate (875/125 mg of AMC) 21% of the interval for 500 mg of CXM, and 0% of the interval for 200 mg of CPO. Consequently, only 875/125 mg of AMC produced a sustained bactericidal effect. A four- to eightfold reduction in susceptibility to CPO and CXM and cross-resistance with cefotaxime, but not penicillin or AMC, were selected following exposure to simulated serum CPO and CXM concentrations. In addition, AMX and AMC were the only agents which consistently produced a >99% reduction in bacterial numbers in time-kill studies using concentrations of antibiotic achieved in middle ear fluid for all three strains of penicillin-resistant
S. pneumoniae
tested.