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PubMed1998

Stool colonization of healthcare workers with selected resistant bacteria.

We examined the carriage of selected resistant bacteria in the stools of healthcare workers who provided direct patient care. Neither vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus, nor Clostridium difficile was recovered from the 55 stool specimens collected. A ceftazidime-resistant Citrobacter freundii was isolated from one specimen. We conclude that the stool of healthcare workers is colonized infrequently with these resistant organisms.

Adult↗

PubMed2001

Detection and typing of extended-spectrum beta-lactamases in clinical isolates of the family Enterobacteriaceae in a medical center in Turkey.

To determine and type the extended-spectrum beta-lactamases (ESBLs) among the family Enterobacteriaceae in a medical center, a total of 668 clinical isolates were screened. Of the 668 isolates, the 80 strains were presumptively defined as ESBL producers according to the result of disk method using ESBL marker antibiotics (aztreonam, ceftazidime, and cefoxitin). These 80 strains were retested with the double-disk synergy test (DDST), the E-test ESBL strip, a 5-microg ceftazidime disk, and agar dilution MICs of ceftazidime with and without clavulonic acid. Isoelectric focusing was performed to confirm ESBL production and type the beta-lactamases. By evaluation of the results of all tests used for ESBL detection together with isoelectric focusing, 33 (4.9%) of the 668 isolates were described as ESBL producer. The positive results of the agar dilution test, DDST, the E-test strip, and 5-microg ceftazidime disk were 32, 26, 27, and 26 of the 33 strains, respectively. ESBL positivity was 48.8% in Klebsiella species, 15.4% in Citrobacter species, 4.9% in Enterobacter species and 1.1% in Escherichia coli strains. The ESBL enzymes frequently determined were SHV-2/6-like (pI 7.6), SHV-5-like (pI 8.2), SHV-4-like (pI 7.8), and SHV-3-like (pI 7). SHV-derived enzymes were commonly observed in Klebsiella spp whereas TEM-related enzymes were seen in E. coli strains. The results of this study indicated that SHV-2/6-derived (pI 7.6) ESBL expression among the isolates of the family Enterobacteriaceae is an important problem in our medical center.

Anti-Bacterial Agents↗

PubMed2001

Multicenter surveillance of antimicrobial resistance of major bacterial pathogens in intensive care units in 2000 in Taiwan.

A susceptibility surveillance study of 1,274 bacterial isolates recovered from various clinical specimens from patients in intensive care units (ICUs) of five major teaching hospitals was carried out from March, 2000, to June, 2000, in Taiwan. This study demonstrated a high rate (66%) of oxacillin resistance in Staphylococcus aureus (ORSA), a high rate of nonsusceptibility to penicillin (intermediate, 50% and highly resistant, 8%), and high rates of cefotaxime nonsusceptibility for S. pneumoniae (intermediate, 29% and resistant, 4%), Enterobacter cloacae (57%), Serratia marcescens (34%), and Citrobacter freundii (60%). High rate of ceftazidime nonsusceptibility for Pseudomonas aeruginosa (22%), and high rates of imipenem nonsusceptibility for P. aeruginosa (15%) and Acinetobacter baumannii (22%) were also found. The percentage (11.9%) of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli was greater than that (11.3%) for Klebsiella pneumoniae. Rates of quinupristin-dalfopristin nonsusceptibility for S. pneumoniae (42%), Enterococcus faecium (71%), and ORSA (39%) were high, but no vancomycin-resistant enterococci were found in this study. The resistance rates of some pathogen varied by institution or type of ICUs. Surveillance for antimicrobial resistance among bacterial pathogens in hospitals, particularly in ICU settings with a preexisting higher resistance burden, is mandatory in establishing and/or modifying guidelines for empirical treatment of severe infections in ICU patients caused by these antimicrobial-resistant pathogens.

Bacteria↗

PubMed1999

Predictive value of urinary cultures in assessment of microbial colonization of ureteral stents.

BACKGROUND AND PURPOSE: Bacterial colonization of indwelling ureteral stents may serve as a nidus for bacteriuria in operations where stents are manipulated. The predictive value of urine cultures in the assessment of stent colonization was examined in 65 patients with indwelling ureteral stents. PATIENTS AND METHODS: Prophylactic antibiotic treatment was administered prior to stent insertion. All patients were ambulatory at the time of investigation and were examined in the outpatient clinic. Urine cultures were taken prior to stent removal after 8 to 150 (mean 64) days. The stents were removed under aseptic conditions, and the proximal and distal ends were cut off and placed in a culture medium for evaluation. None of the patients was treated for urinary tract infection prior to stent removal. RESULTS: Bacteriuria was found in 15% of the patients. In 35 patients (54%), urine and stent cultures were sterile. In 20 patients (31%), the urine culture was sterile but the stent was colonized (Enterococcus 9, E. coli 5, Staphylococcus aureus 2, S. epidermidis 2, Candida 1, Citrobacter diversus 1). One patient had a sterile stent culture with bacteriuria. In 9 patients (13.5%), urine and stent cultures were identical (E. coli 4, Pseudomonas 4, Candida 1). The incidence of stent colonization did not correlate with stent dwelling time. The sensitivity of urine cultures for the detection of stent colonization was poor, being 31% only. In a specific patient with negative urine culture, the probability of stent colonization was 36%. CONCLUSION: A sterile urine culture does not rule out the stent itself being colonized. Therefore, patients with indwelling ureteral stents and a sterile urine culture may benefit from prophylactic antibiotic treatment prior to endourologic procedures. The prophylactic regimen must provide coverage for common gram-negative uropathogens as well as gram-positive bacteria, including enterococci.

Adult↗

PubMed1995

Five-year survey of cefotaxime resistance in Spain.

During 1991-1995 a Spain collaborative study group surveyed the resistance to cefotaxime both in community as well as in hospital isolates of bacteria. The isolates tested during the study period of 5 years were 813, 875, 3631, 3184, and 3050 strains, respectively. Antimicrobial activity of cefotaxime was assayed by broth or agar microdilution, in accordance with criteria of the National Committee of Clinical Laboratory Standards (NCCLS). Cefotaxime resistance included 2.5% of all isolates: 2.6% Enterobacteriaceae, 1.7% Streptococcus pneumoniae, 0.5% Haemophilus influenzae, 0.0% Haemophilus spp., and 0.0% Moraxella catarrhalis. The overall incidence of resistance to cefotaxime decreased fro member of Enterobacteriaceae from 3.6% in 1991 to 2.5% in 1995. The incidence of resistance varied with the species and was highest in Enterobacter and in Citrobacter freundii.

Bacterial Infections↗

PubMed2006

Occurrence and characterization of carbapenemase-producing Enterobacteriaceae: report from the SENTRY Antimicrobial Surveillance Program (2000-2004).

Emergence and dissemination of Enterobacteriaceae isolates harboring carbapenemases in various geographic regions represents a significant threat to the management of nosocomial infections. Enterobacteriaceae isolates from the SENTRY Antimicrobial Surveillance Program (2000-2004) demonstrating decreased susceptibility to imipenem and meropenem (minimum inhibitory concentration [MIC], > or =2 mg/L) were evaluated for the production of metallo-beta-lactamases and serine carbapenemases using disk approximation and polymerase chain reaction (PCR) tests. Carbapenemase-producing strains were epidemiologically typed by automated riboprinting and pulsed-field gel electrophoresis (PFGE) to establish clonality. Among 37,557 Enterobacteriaceae (5 genus groups) evaluated, 119 (0.32%) had increased carbapenem MIC values, and a carbapenemase was identified in 51 (42.9%) of these strains. KPC-2 and KPC-3 were the most frequently occurring carbapenemases (24 isolates, 20.2%) in the United States and were detected in Klebsiella spp, Citrobacter spp., Enterobacter spp., and Serratia marcescens strains isolated in New York, Arkansas, and Virginia. SME-2-producing S. marcescens were isolated in the New York City area, Texas, and Ohio, while NMC-A was found in one E. cloacae strain from New York. In contrast, metallo-beta-lactamases were prevalent in Europe. IMP-1-producing E. cloacae (11 isolates) were detected in Turkey, while VIM-1-producing strains were found in Italy (Enterobacter spp.) and Greece (Klebsiella pneumoniae). Clonal dissemination of carbapenemase-producing strains was observed in several medical centers on both continents. The occurrence of carbapenemases in various Enterobacteriaceae remains rare but appears to be spreading geographically (not in Latin America), mainly with metallo-beta-lactamases being found in Mediterranean Europe and KPC enzymes in the New York City area.

Anti-Bacterial Agents↗

PubMed1993

Emergence of antimicrobial resistance in gram-negative bacilli causing bacteremia during therapy.

Treatment of serious infections caused by gram-negative bacilli with beta-lactam antimicrobial agents can induce Class I beta-lactamase production. This phenomenon can result in resistant microorganisms, and has been postulated to be a cause of therapeutic failure. The charts of patients bacteremic with Pseudomonas aeruginosa, Serratia marcescens, Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Providencia species (n = 120) during a 3-year period were reviewed to determine how common the emergence of resistance was, and to determine if in vitro susceptibility testing was a reliable therapeutic guide. Emergence of resistance was believed to occur when a subsequent bacteremic isolate showed at least a fourfold increase in minimum inhibitory concentration accompanied by a change of interpretive susceptibility category. In the group of patients who survived at least 48 hours that received beta-lactam therapy (n = 76), one case of emergence of resistance was identified (1.3%). Emergence of resistance to beta-lactam antimicrobial agents did not commonly cause therapeutic failure at our institution, and susceptibility testing of gram-negative bacilli by usual methods was a reliable guide to antimicrobial therapy.

Anti-Bacterial Agents↗

PubMed1977

Interaction of blood with enterobacteriaceae: hemolysis, hemagglutination, fibrinolysis.

One thousand eighty enterobacteriaceae, isolated during a period of three months, were tested for the presence of hemolysis, hemagglutination and fibrinolysis on human erythrocytes and plasma. The fibrinolysis on human erythrocytes and plasma. The Escherichia coli have the greatest diversity of action on the blood. Of 481 strains, 32.9% were hemolytic, 21.9% fibrinolytic, and 10.5% hemagglutinating. Of 190 strains of Klebsiella, 95.2% were fibrinolytic. Of 53 strains of Enterobacter, 90.6% were fibrinolytic, and of 53 strains of Enterobacter hafniae, 66% were fibrinolytic. Of seven strains of Serratia, 28.5% were hemolytic and 14.3% fibrinolytic. The Proteae were mostly fibrinolytic: 60.5% of 141 strains, with three strains being hemolytic and fibrinolytic. Of 19 strains of Citrobacter, 52.6% were fibrinolytic only. Providenica, Salmonella and Shigella did not interact with human blood. The patterns of blood interactions with the different species of Enterobacteriaceae are of value in the evaluation of the pathogenesis of the infections and septicemias they cause. Their study is an essential step in the understanding of the sequence of events leading to severe disturbances of the blood-clotting mechanism.

Enterobacteriaceae↗

PubMed1979

Bacteriocin typing of Serratia marcescens. A simplified system.

The authors describe a simplified system for the detection of bacteriocin production by Serratia marcescens with the use of six indicator strains, which include Escherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Enterobacter aerogenes (two strains), and Serratia rubidaea grown on arabinose minimal medium plates. Of the 64 possible bacteriocin types, 11 were observed; 66% of the isolates tested were found to be one of three types. Occasionally more than one bacteriocin type was observed in an individual specimen; however, serotyping or antibiograms, or both, also indicated this was a different strain. The marcescin types were stable markers. With the use of this technic, different endemic strains of Serratia were shown to predominate in various areas of the hospital. In addition, when urinary tract isolates were compared with respiratory tract isolates, significant differences were found in the predominate types. The typing of these isolates by bacteriocin production was supported by serotype and antibiotype findings. The results suggest that this simple system may be a useful tool in a general hospital.

Bacteriocins↗

PubMed1988

Evaluation of the IDS RapID SS/u system for rapid identification of urinary microorganisms.

The accuracy of a new rapid identification system for common urinary pathogens was compared with that of conventional methods and of miniaturized 18-24-hour identification panels. The rapid system, RapID SS/u (Innovative Diagnostic System Inc., Atlanta, GA) is a non-growth-dependent micro-method that identifies selected gram-negative bacilli, gram-positive cocci, and yeasts in two hours by detection of constitutive enzymes acting on chromogenic substrates. A total of 185 representative clinical urinary isolates were tested, including 24 gram-positive cocci, 140 gram-negative bacilli, and 21 yeasts. Identifications by the rapid system were compared with the ones obtained by reference conventional methods for gram-positive cocci and yeasts. For gram-negative bacilli, identifications were compared with the ones obtained by MicroScan Combo Panel (American MicroScan, Mahwah, NJ), and all discrepancies were resolved by testing with API 20E (Analytab Products, Plainview, NY). Overall, the RapID SS/u system correctly identified to genus 160 of 185 isolates (86.5%). For 14 additional isolates (7.6%) the system provided probability overlap identifications that required further testing. Two (1%) isolates failed to be identified, and nine isolates (4.9%) were misidentified by the system. Discrepancies involved five strains of Citrobacter, one Enterobacter, one Morganella, and one Providencia species. The authors conclude that the RapID SS/u system provided rapid and accurate genus identification of most microorganisms commonly isolated from urine.

Humans↗

PubMedDate not supplied

Inducible beta-lactamases: clinical and epidemiologic implications for use of newer cephalosporins.

The emergence of resistance to multiple beta-lactam antibiotics is a major problem in patients infected with organisms that characteristically produce inducible beta-lactamases--e.g., species of Pseudomonas, Enterobacter, Serratia, Citrobacter, indole-positive Proteus, and Providencia. Resistance has emerged in 14%-56% of patients infected with these organisms and treated with one of the newer cephalosporins. The emergence of resistance has been associated with clinical failure or relapse in 25%-75% of these patients. Combination therapy appears to have little impact on rates of resistance or its clinical consequences. Multiply resistant organisms have spread widely in some hospitals, and this trend has been correlated closely with the extent of use of the newer cephalosporins. The magnitude of the problem is frequently underestimated because many properly performed susceptibility tests fail to detect resistance when it is actually present and because some methods used to calculate rates minimize the impact of the emergence of resistance among organisms with inducible beta-lactamases.

Adolescent↗

PubMedDate not supplied

Synergy of fluoroquinolones with other antimicrobial agents.

Synergy resulting from the combination of ciprofloxacin and an antipseudomonal penicillin has been reported for 20%-50% of isolates of Pseudomonas aeruginosa. A similar effect has also been reported for the combination of ciprofloxacin and fosfomycin. In contrast, the combination of quinolones and aminoglycosides rarely showed synergy when tested against P. aeruginosa. Most studies have shown that the combination of beta-lactams or aminoglycosides with quinolones is indifferent against Escherichia coli, Klebsiella species, Enterobacter species, Citrobacter species, and Serratia species. The combination of ciprofloxacin and chloramphenicol can be antagonistic against E. coli. In general, the combination of quinolone antibiotics with other drugs tested against staphylococci, enterococci, and anaerobic species has shown indifference. The neutropenic mouse model of infection has demonstrated the synergistic effect of ciprofloxacin plus antipseudomonal penicillins; the combination of ciprofloxacin and rifampin has been superior to single agents in experimental Staphylococcus aureus osteomyelitis. Ciprofloxacin has been the quinolone studied most thoroughly, and few data are available about the combination of other quinolones with other antimicrobial agents. Overall, the occurrence of synergy when quinolones are combined with other antimicrobial agents is infrequent, and clinical studies that demonstrate the clinical relevance of data from in vitro and animal models of infection are not available. However, data from in vitro and animal model studies indicate that the combination of a quinolone with other antimicrobial agents rarely results in antagonism.

4-Quinolones↗

PubMed1992

Review of the in vitro antibacterial activity of cefprozil, a new oral cephalosporin.

Cefprozil is a newer oral cephalosporin with a spectrum of activity against organisms that include gram-positive and gram-negative pathogens. A review of published data shows that cefprozil is active (susceptibility, less than or equal to 8 micrograms/mL; moderate susceptibility, 16 micrograms/mL; resistance, greater than or equal to 32 micrograms/mL) against gram-positive species such as streptococci, methicillin-susceptible staphylococci, and Listeria monocytogenes; it may have marginal activity against some enterococci. Among the gram-negative species, cefprozil has activity against Escherichia coli, Proteus mirabilis, Citrobacter diversus, Klebsiella pneumoniae, Klebsiella oxytoca, Haemophilus influenzae, and Moraxella catarrhalis. For anaerobic species, cefprozil has activity against clostridial species, including Clostridium difficile, peptostreptococci, and possibly Bacteroides melaninogenicus and Eubacterium. The activity of cefprozil is generally greater than that of cephalexin and generally similar to that of cefaclor. In these reports, cefprozil showed more in vitro activity than cephalexin and cefaclor against penicillin-resistant pneumococci, penicillin-resistant viridans streptococci, beta-lactamase-positive methicillin-susceptible Staphylococcus aureus, and C. difficile, although the clinical significance of some of these differences has yet to be studied.

Cephalosporins↗

PubMed1993

Peritonsillar abscess, retropharyngeal abscess, mediastinitis, and nonclostridial anaerobic myonecrosis: a case report.

Peritonsillar abscess is a potentially life-threatening complication of acute tonsillitis. On occasion, peritonsillar abscess can extend to neck spaces and/or to the mediastinum. We describe a case of a patient with a peritonsillar abscess that extended to the neck, producing bilateral retropharyngeal abscesses and myonecrosis of the strap muscles. Culture of a specimen of the necrotic muscle yielded Prevotella intermedia, Prevotella buccae, Lactobacillus catenaforme, another Lactobacillus species, Peptostreptococcus anaerobius, and some nonanaerobes. Culture of the peritonsillar abscess yielded P. intermedia and P. buccae plus P. anaerobius, Peptostreptococcus asaccharolyticus, Bifidobacterium dentium, viridans and group F streptococci, and Citrobacter diversus. Culture of the retropharyngeal abscess yielded Fusobacterium nucleatum and Actinomyces odontolyticus in addition to most of the aforementioned organisms. The patient underwent repeated drainage and debridement procedures and was treated with various antimicrobial agents and ultimately recovered. This case highlights the polymicrobial nature of peritonsillar abscess and the serious complications that this infection may lead to.

Abscess↗

PubMed1997

The most frequent aminoglycoside resistance mechanisms--changes with time and geographic area: a reflection of aminoglycoside usage patterns? Aminoglycoside Resistance Study Groups.

The aminoglycoside resistance mechanisms revealed by two surveys in Europe and other countries have been compared to those revealed in earlier studies. Mechanisms have become more complex in all bacterial groups. In Providencia, Serratia, Pseudomonas, Acinetobacter, and Staphylococcus species isolates, genus-specific mechanisms were very common, and it was not possible to see differences between different geographic areas. In other Enterobacteriaceae, the increasing complexity of mechanisms was most often caused by combinations of gentamicin-modifying enzymes with AAC(6')-I, which acetylates amikacin but not gentamicin. The occurrence of these combinations varied by geographical region and among hospitals. The frequency of these combinations correlated with aminoglycoside usage in either the geographical regions or in individual hospitals. These broad-spectrum combinations occurred most frequently in Citrobacter, Enterobacter, and Klebsiella species but also occurred in Escherichia, Morganella, Proteus, Salmonella, and Shigella species. Often the only clinically available aminoglycoside that retained its normal activity was isepamicin.

Acinetobacter↗

PubMedDate not supplied

Cefotaxime: a review of in vitro antimicrobial properties and spectrum of activity.

Cefotaxime has remarkable potency against all Enterobacteriaceae, including Enterobacter species, Citrobacter freundii, Serratia marcescens, and Morganella morganii, Proteus vulgaris, and Providencia species--all of which are resistant to earlier cephalosporins. Cefotaxime generally inhibits greater than 90% of enteric bacilli at concentrations of less than or equal to 0.5 microgram/ml; in one study it inhibited greater than 98% of isolates at less than or equal to 8 micrograms/ml. For staphylococci and nonenterococcal streptococci, the mean values for the minimal inhibitory concentration50 (MIC50) of cefotaxime (i.e., the lowest concentration inhibiting growth of 50% of tested strains) are 1.1-1.9 microgram/ml and 0.01-0.05 microgram/ml, respectively. Cefotaxime is inactive against Streptococcus faecalis and most other serogroup D streptococci. It is moderately active against Pseudomonas aeruginosa (MIC50, 19 microgram/ml) and Acinetobacter calcoaceticus subspecies anitratus (MIC50, 18 microgram/ml). Because the activity of cefotaxime against other pseudomonads and nonfermentative gram-negative bacilli varies, in vitro susceptibility testing must be used as a guide to therapy. Cefotaxime is potent against Haemophilus influenzae and Neisseria species. Infections due to beta-lactamase-producing gonococci have been treated effectively with cefotaxime (MIC, mode = less than or equal to 0.004 microgram/ml). Most anaerobes are highly susceptible to cefotaxime, but the minimal inhibitory concentrations for 10%-20% of Bacteroides fragilis strains (MIC50, 5.3 microgram/ml) and other Bacteroides species may exceed obtainable serum concentrations. The potent antimicrobial activity of cefotaxime appears to be the result of a combination of characteristics which include: beta-lactamase stability (types I, III, IV, and V), good ability to pass through the cell membrane, strong affinity for lethal penicillin-binding proteins 1a, 1b(s), and 3, minimal limitation by the inoculum effect, and bactericidal action at or close to the inhibitory concentration. Clinically useful methods of susceptibility testing have been developed and can be recommended for clinical laboratory use.

Bacteria↗

PubMedDate not supplied

Comparative activity of cefotaxime and selected beta-lactam antibiotics against Haemophilus influenzae and aerobic gram-negative bacilli.

The activity of cefotaxime was compared with that of ampicillin, moxalactam, and cefoperozone against 50 isolates of Haemophilus influenzae and with that of ampicillin, carbenicillin, cephalothin, cefoxitin, cefamandole, cefazolin, and several other established and investigational beta-lactam antibiotics against several hundred isolates of gram-negative aerobic enteric bacilli. Minimal inhibitory concentrations of the drugs were determined by the agar plate dilution technique for H. influenzae and by the microtiter broth dilution technique for the other pathogens. Cefotaxime was the most active agent against H. influenzae; it was 20 times more active than ampicillin. It was also the most active agent against Escherichia coli, Klebsiella pneumoniae, nontyphoid Salmonella species, and Yersinia enterocolitica. Cefotaxime was among the most active agents against Enterobacter cloacae, Citrobacter species, Shigella species, Proteus mirabilis, and Acinetobacter calcoaceticus. None of the new cephalosporins or penicillin inhibited greater than 90% of the isolates of Pseudomonas aeruginosa at concentrations of less than or equal to 16 micrograms/ml; these drugs were, however, more active than carbenicillin.

Ampicillin↗

PubMedDate not supplied

Treatment of urinary tract infections with cefotaxime: noncomparative and prospective comparative trials.

Three studies evaluated the efficacy of cefotaxime for the treatment of urinary tract infections. An open, multicenter, noncomparative trial included 477 patients who received a usual dose of 2 g of intravenous or intramuscular cefotaxime daily for five to 10 days. The maximal daily dosage in severe cases was 12 g. Pathogens included Escherichia coli and species of Citrobacter, Pseudomonas, Klebsiella, Enterobacter, Serratia, Morganella, Providencia, and Proteus. Of all the causative organisms, 83.6% were eradicated in the 271 patients who could be evaluated. The other two studies were prospective, randomized comparisons of cefotaxime (392 patients) with cefazolin (250 patients) for the treatment of urinary tract infections caused by microorganisms susceptible to both antibiotics. The treatment schedule was the same as that in the first study. Results of these two prospective studies were pooled. Cefotaxime eradicated 90% of all pathogens, and cefazolin eradicated 72%. Cefotaxime was significantly more effective (P less than 0.01) than cefazolin in eradicating E. coli and Proteus mirabilis. A satisfactory clinical response was obtained in 98.1% of patients given cefotaxime and in 87.6% of those given cefazolin (P less than 0.01).

Adolescent↗