Biomedical subjects

D M Citron

Publications and source records attributed to D M Citron.

At least 91 records · Page 5Linked to original sources

PubMed1990

Recovery of an unusual Flavobacterium group IIb-like isolate from a hand infection following pig bite.

An unusual gram-negative rod (RMA 1571) was isolated from a hand infection following a pig bite. This unclassified isolate was characterized by growth requirements, microscopic examination, biochemical characteristics, antimicrobial susceptibility tests, and cellular fatty acid analysis. It was indole positive and produced yellow-pigmented growth, which placed it in the genus Flavobacterium, but its other features, including cellular fatty acid analysis, did not appear to be those of a named species.

Animals↗

PubMed1988

Lack of in vitro efficacy of oral forms of certain cephalosporins, erythromycin, and oxacillin against Pasteurella multocida.

The in vitro susceptibility of human isolates of Pasteurella multocida to oral antimicrobial agents from our current study and from a review of the literature suggests that dicloxacillin (oxacillin), erythromycin, clindamycin, cephalexin, cefaclor, and cefadroxil should not be used for empiric therapy of animal bite wounds. Agents that were consistently active against P. multocida were penicillin, ampicillin, amoxicillin-clavulanic acid, tetracycline, minocycline, chloramphenicol, trimethoprim-sulfamethoxazole, and cefuroxime. Possible reasons for the confusion regarding the activity of oral cephalosporins are addressed.

Animals↗

PubMed1988

Comparative activities of cefuroxime, amoxicillin-clavulanic acid, ciprofloxacin, enoxacin, and ofloxacin against aerobic and anaerobic bacteria isolated from bite wounds.

We studied the comparative in vitro activities of 10 oral antimicrobial agents against 147 aerobic and 61 anaerobic bacteria making up species in 13 genera (Staphylococcus aureus, streptococci, Eikenella corrodens, Pasteurella multocida, Haemophilus-Actinobacillus spp., M-5, EF-4, Moraxella spp., Flavobacterium IIb, Bacteroides melaninogenicus, Bacteroides spp., Fusobacterium spp., and Peptostreptococcus spp.) that were isolated from bite wounds. Cefuroxime was generally greater than fourfold more active than cephalexin and cefadroxil against all aerobic isolates, including Pasteurella multocida. The fluoroquinolones were highly active against most aerobic isolates but were less active against anaerobic isolates. Ciprofloxacin was generally more active than either enoxacin or ofloxacin. Discrepancies of greater than 30% in the interpretation of susceptibilities between break points suggested by the National Committee for Clinical Laboratory Standards and those related to oral dose peak levels (one-half to one-quarter of maximum achievable concentrations) were noted in 14% (18 of 130) of the instances.

Amoxicillin↗

PubMed1988

Annual incidence, epidemiology, and comparative in vitro susceptibilities to cefoxitin, cefotetan, cefmetazole, and ceftizoxime of recent community-acquired isolates of the Bacteroides fragilis group.

The six species of the Bacteroides fragilis group are potent pathogens and commonly have different susceptibility patterns. We determined the relative annual isolation rate of anaerobic bacteria and the susceptibility of B. fragilis group species isolated during 1987 at two community hospitals. The relative frequencies of isolation of 261 strains were as follows: B. fragilis, 61%; B. thetaiotaomicron, 17%; B. distasonis, 7%; B. vulgatus, 6%; B. ovatus, 5%; and B. uniformis, 4%. A total of 234 recent clinical isolates were tested against cefmetazole, cefotetan, cefoxitin, ceftizoxime, clindamycin, imipenem, and piperacillin by a brucella agar dilution method. Imipenem was the most active agent tested with all but three isolates (two B. vulgatus and one B. distasonis) susceptible to less than 2 micrograms/ml. Of the cephalosporins tested, cefoxitin, cefotetan, and cefmetazole were relatively equal against B. fragilis, with 93 to 98% of strains susceptible to 32 micrograms/ml. Ceftizoxime was less active, with an MIC for 90% of strains tested of 128 micrograms/ml and only 75% of isolates susceptible to 32 micrograms/ml. Against B. ovatus, B. vulgatus, B. thetaiotaomicron, and B. uniformis, cefoxitin showed a two- to threefold-superior activity compared with that of cefotetan and cefmetazole. In general, ceftizoxime was much less active, except against B. distasonis, for which 78% of isolates were susceptible to 32 micrograms/ml compared with 68% for cefoxitin, 19% for cefmetazole, and 16% for cefotetan. Clindamycin and piperacillin showed activity similar to that of cefoxitin, except piperacillin was less active versus B. vulgatus and B. distasonis. We therefore suggest that clinical laboratories determine the species of B. fragilis group isolates as well as perform susceptibility studies on the isolates. Clinicians should be aware that while B. fragilis is the most frequent isolate, 38% of isolates are from other, more resistant B. fragilis group species.

Bacteroides Infections↗

PubMed1988

Immunoblots, antimicrobial resistance, and bacteriophage typing of oxacillin-resistant Staphylococcus aureus.

An immunoblotting system was developed for typing of oxacillin-resistant Staphylococcus aureus. Clinical isolates recovered during a 40-month period at a single institution were evaluated with this typing scheme. Results were compared with susceptibility patterns and with bacteriophage typing results for 100 clinical isolates and with plasmid fingerprints for 14 isolates. Immunoblotting was found to be a useful method with good reproducibility that distinguished seven major groups of patient isolates that were clinically and epidemiologically related. Susceptibility patterns showed specific correlations with other typing results but were inferior to immunoblotting and phage typing for differentiating major groups of organisms. Plasmid profiles failed to distinguish two major groups that were readily identified by immunoblots and phage typing. There was evidence of increasing antimicrobial resistance of endemic hospital strains. Immunoblotting correlated well with phage typing, offered an alternative method for typing isolates that could not be typed by phage typing, and was superior to susceptibility testing and plasmid profiles for distinguishing different groups of oxacillin-resistant S. aureus at our institution.

Bacteriophage Typing↗

PubMed1988

Comparative in vitro activity of imipenem and 15 other antimicrobial agents against clinically important aerobic and anaerobic bacteria.

The comparative susceptibility of over 400 strains of aerobic and anaerobic pathogens, isolated from clinical specimens in late 1987 and early 1988, to imipenem and 15 other antimicrobial agents was studied using a uniform broth microdilution technique recommended by the National Committee for Clinical Laboratory Standards. Imipenem had the widest spectrum of activity and was consistently the most active agent tested. It was active against aerobic gram-positive cocci, aerobic gram-negative bacilli, and anaerobic bacteria.

Anti-Bacterial Agents↗

PubMed1987

Effect of inoculum size on in vitro activity of norfloxacin against fecal anaerobic bacteria. Rationale for selective decontamination of the digestive tract.

Previous studies have shown that anaerobic bacteria are susceptible to norfloxacin at the levels attained in the feces. Conversely, studies in laboratory animals and neutropenic humans using norfloxacin for selective decontamination of the digestive tract have shown that norfloxacin markedly reduces the aerobic enteric flora without reducing fecal anaerobic flora. In an effort to resolve this paradox, the effect of a 10(9) colony-forming units (cfu)/ml inoculum, which is more reflective of actual fecal counts than the standard 10(5) cfu/ml inoculum, on the activity of norfloxacin against two fecal Escherichia coli isolates and 16 fecal anaerobic isolates was studied. The results showed a marked inoculum effect at 10(9) cfu/ml for most anaerobic isolates but not for the E. coli strains tested. At 256 micrograms/ml, all E. coli were killed while the anaerobic bacteria maintained colony counts greater than or equal to 10(9) cfu/ml. Hence, the lack of anaerobic activity (minimal inhibitory concentration greater than or equal to 512 micrograms/ml) at higher fecal inocula might explain the utility of norfloxacin in selective decontamination of the bowel.

Adult↗

PubMed1987

Ciprofloxacin versus cinoxacin in therapy of urinary tract infections. A randomized, double-blind trial.

In a prospective, randomized, double-blind trial, ciprofloxacin (250 mg orally, twice daily) was compared with cinoxacin (500 mg orally, twice daily) in 60 patients with urinary tract infections. Most patients were women with uncomplicated urinary tract infections. Escherichia coli was the most common isolate (36 patients). Clinical and microbiologic cure occurred in 20 of 24 (83 percent) evaluable patients treated with ciprofloxacin, compared with 15 of 21 (71 percent) evaluable patients treated with cinoxacin. Ciprofloxacin was well tolerated and had a low incidence of minor side effects that included Candida vaginitis, headache, and gastrointestinal intolerance. Relapse or failed therapy was not associated with the development of resistance.

Adolescent↗

PubMed1987

Potential of topical norfloxacin therapy. Comparative in vitro activity against clinical ocular bacterial isolates.

Norfloxacin, a new fluoroquinolone antibiotic related to nalidixic acid, was evaluated as a topical agent for clinical efficacy in bacterial eye infections. This study reports on the comparative in vitro activity of norfloxacin and ten topical antibiotics (nalidixic acid, polymyxin B, colistin, bacitracin, chloramphenicol, sulfamethoxazole, tetracycline, erythromycin, gentamicin, and tobramycin) against 203 pathogenic eye isolates of 17 genera (37 species). In general, norfloxacin had the greatest potency and broadest spectrum of activity of the agents tested. It was active against Staphylococcus aureus (minimal inhibitory concentration against 90% [MIC90], less than or equal to 1.0 microgram/mL), coagulase-negative staphylococci (MIC90, less than or equal to 1.0 microgram/mL), Pseudomonas aeruginosa (MIC90, less than or equal to 1.0 microgram/mL), and Haemophilus organisms (MIC90, less than or equal to 1.0 microgram/mL).

Administration, Topical↗

PubMed1987

Impact of prolonged incubation on disk diffusion susceptibility test results for Staphylococcus aureus.

Because strains of Staphylococcus aureus that are resistant to penicillinase-resistant penicillins may be difficult to detect in the clinical laboratory, a variety of changes in methodology have been suggested to increase their detection. In 1984, the West Los Angeles Veterans Administration Medical Center experienced an increase in clinically significant strains of oxacillin-resistant S. aureus. To insure that such strains would not be missed by the disk diffusion test methods employed for routine testing, changes in methodology were insituted. These included interpreting zone diameters around oxacillin disks at 48 h of incubation. We collected 139 isolates from patients thought to have oxacillin-resistant S. aureus based on these test results and later retested the isolates using microdilution MIC testing. Only 85 isolates (61%) had microdilution oxacillin MICs of greater than or equal to 8.0 micrograms/ml, whereas 54 (39%) had oxacillin MICs of less than or equal to 2.0 micrograms/ml. A review of medical records revealed that in 1 year there were 98 patients with isolates appearing resistant by disk diffusion but not confirmed by microdilution MICs; many patients were placed in isolation and treated with specific antimicrobial agents. We conclude that incubation of oxacillin disk diffusion tests for longer than 24 h in conjunction with disregard for resistance to other classes of antimicrobial agents may result in an unacceptably high degree of false resistance results. Because the resistance of S. aureus has important therapeutic and infection control implications, it is necessary to recognize problems that may result in ambiguous or inaccurate susceptibility results.

Humans↗

PubMed1986

Comparative in vitro activities of amoxicillin-clavulanic acid and imipenem against anaerobic bacteria isolated from community hospitals.

The susceptibilities of recent clinical isolates of anaerobic bacteria from two community hospitals were determined. Thirty percent of pigmented Bacteroides species and bile-sensitive, nonpigmented Bacteroides species produced penicillinase and were resistant to amoxicillin. Cefoxitin and clindamycin showed good activity against most strains, with the exception of rare isolates of the Bacteroides fragilis group and some strains of Clostridium species. While amoxicillin was not active against B. fragilis and other members of the B. fragilis group, amoxicillin-clavulanic acid was very active against almost all of these organisms. Imipenem was the most potent agent against all strains tested.

Amoxicillin↗

PubMed1986

Susceptibility of bite wound bacteria to seven oral antimicrobial agents, including RU-985, a new erythromycin: considerations in choosing empiric therapy.

The susceptibility of 93 aerobic and 59 anaerobic bacteria isolated from human and animal bite wounds was determined by agar dilution. No agent tested (penicillin, oxacillin, cephalexin, sulfamethoxazole-trimethoprim, minocycline, erythromycin, and RU-965) was consistently active against all isolates. A total of 21% of the Bacteroides species, all isolated from human bites, were resistant to penicillin; 14 and 18% of the Pasteurella multocida isolates were resistant to erythromycin and oxacillin, respectively.

Animals↗

PubMed1986

Susceptibility of Eikenella corrodens to newer and older quinolones.

The susceptibilities of 44 clinical strains and a reference strain (ATCC 23834) of Eikenella corrodens were determined by agar dilution. All isolates were very susceptible (MICs, less than 2 micrograms/ml) to amifloxacin, ciprofloxacin, difloxacin, enoxacin, norfloxacin, ofloxacin, and Win 35439.

Bacteroides↗

PubMed1986

Failure of rapid agglutination methods to detect oxacillin-resistant Staphylococcus aureus.

Although a latex agglutination test (StaphAurex) and a hemagglutination test (Staphyloslide) correctly identified all strains of Staphylococcus aureus that were susceptible or had intermediate susceptibility to oxacillin, 17 of 73 (23%) and 18 of 73 (25%) strains of oxacillin-resistant S. aureus were not identified by StaphAurex and Staphyloslide, respectively. All strains not detected were resistant to trimethoprim-sulfamethoxazole and rifampin.

Drug Combinations↗

PubMed1985

Comparative in vitro activity of cefbuperazone against anaerobic bacteria isolated from community hospitals.

The activity of cefbuperazone against 266 strains of anaerobic bacteria was determined by the agar dilution method and compared with cefoxitin, moxalactam, piperacillin, and clindamycin. All strains were recent clinical isolates from community hospitals. All agents tested showed good activity against Bacteroides fragilis, Fusobacterium spp., Propionibacterium spp., Clostridium septicum, Clostridium perfringens, and the anaerobic, gram-positive cocci and gram-negative cocci. Cefbuperazone, cefoxitin, and moxalactam had poor activity against Bacteroides thetaiotaomicron, Bacteroides ovatus, and Bacteroides distasonis. The susceptibility of other Clostridium spp., Lactobacillus spp., and Eubacterium lentum was variable. Our community hospital isolates showed a difference in susceptibility patterns from those reported from university and research centers. This supports the recommendation that clinical microbiology laboratories, including those in community hospitals, need to perform susceptibility testing on representative clinical isolates.

Bacteria, Anaerobic↗

PubMed1985

Comparative activity of the quinolones against anaerobic bacteria isolated at community hospitals.

The in vitro activity of five quinolone compounds, amoxicillin, and clindamycin against 118 strains of anaerobic bacteria isolated at community hospitals was determined by an agar dilution method. Nalidixic acid and cinoxacin had poor activity, and norfloxacin and enoxacin showed relatively poor activity. Ciprofloxacin was active against Bacteroides fragilis, Fusobacterium species, Clostridium perfringens, and gram-positive cocci. At peak levels achievable in the feces, norfloxacin and enoxacin had moderate activity.

Amoxicillin↗

PubMed1985

Comparative in vitro inhibitory and killing activity of cefpirome, ceftazidime, and cefotaxime against Pseudomonas aeruginosa, enterococci, Staphylococcus epidermidis, and methicillin-susceptible and -resistant and tolerant and nontolerant Staphylococcus aureus.

With a macrotube dilution method, MICs and MBCs were determined for three aminothiazolyl cephalosporins, cefpirome (HR 810), ceftazidime, and cefotaxime, against Pseudomonas aeruginosa, enterococci, Staphylococcus epidermidis, and methicillin-resistant, -susceptible, and -tolerant strains of Staphylococcus aureus. Comparatively, cefpirome was the most active agent against all gram-positive cocci, including enterococci and methicillin-resistant S. aureus, and was as active as ceftazidime against P. aeruginosa. MBCs of cefpirome were within two dilutions of the MICs for 91% of P. aeruginosa and 90% of gram-positive cocci strains tested, except methicillin-resistant S. aureus, for which the MBCs were within three dilutions for 90% of strains.

Bacteria↗

PubMed1984

Susceptibility of Eikenella corrodens to penicillin, apalcillin, and twelve new cephalosporins.

The susceptibility of 29 strains of Eikenella corrodens to penicillin, apalcillin, and 12 new cephalosporins was determined by the agar dilution method. Most strains were resistant to cefsulodin, and some were resistant to apalcillin and cefpiramide. Although all strains were susceptible to the other cephalosporins tested, most of those drugs were as active as or less active than penicillin. Susceptibility testing of isolates should be performed whenever a cephalosporin is used to treat infections involving E. corrodens.

Ampicillin↗