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PubMed2001

Evidence of in vivo transfer of a plasmid encoding the extended-spectrum beta-lactamase TEM-24 and other resistance factors among different members of the family Enterobacteriaceae.

The epidemiological study of several multidrug-resistant Enterobacteriaceae isolated from five patients demonstrated in vivo dissemination of a 100-kb plasmid encoding the extended-spectrum beta-lactamase TEM-24 from a clonal strain of Enterobacter aerogenes to different strains of Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris, Proteus mirabilis, and Serratia marcescens.

Anti-Bacterial Agents↗
PubMed2003

Characterization of clinical isolates of Enterobacteriaceae from Italy by the BD Phoenix extended-spectrum beta-lactamase detection method.

Production of extended-spectrum beta-lactamases (ESBLs) is an important mechanism of beta-lactam resistance in Enterobacteriaceae: Identification of ESBLs based on phenotypic tests is the strategy most commonly used in clinical microbiology laboratories. The Phoenix ESBL test (BD Diagnostic Systems, Sparks, Md.) is a recently developed automated system for detection of ESBL-producing gram-negative bacteria. An algorithm based on phenotypic responses to a panel of cephalosporins (ceftazidime plus clavulanic acid, ceftazidime, cefotaxime plus clavulanic acid, cefpodoxime, and ceftriaxone plus clavulanic acid) was used to test 510 clinical isolates of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Providencia stuartii, Morganella morganii, Enterobacter aerogenes, Enterobacter cloacae, Serratia marcescens, Citrobacter freundii, and Citrobacter koseri. Of these isolates, 319 were identified as ESBL producers, and the remaining 191 were identified as non-ESBL producers based on the results of current phenotypic tests. Combined use of isoelectric focusing, PCR, and/or DNA sequencing demonstrated that 288 isolates possessed bla(TEM-1)- and/or bla(SHV-1)-derived genes, and 28 had a bla(CTX-M) gene. Among the 191 non-ESBL-producing isolates, 77 isolates produced an AmpC-type enzyme, 110 isolates possessed TEM-1, TEM-2, or SHV-1 beta-lactamases, and the remaining four isolates (all K. oxytoca strains) hyperproduced K1 chromosomal beta-lactamase. The Phoenix ESBL test system gave positive results for all the 319 ESBL-producing isolates and also for two of the four K1-hyperproducing isolates of K. oxytoca. Compared with the phenotypic tests and molecular analyses, the Phoenix system displayed 100% sensitivity and 98.9% specificity. These findings suggest that the Phoenix ESBL test can be a rapid and reliable method for laboratory detection of ESBL resistance in gram-negative bacteria.

Algorithms↗
PubMed2004

Molecular epidemiology of Enterobacteriaceae isolates producing extended-spectrum beta-lactamases in a French hospital.

In 2002, 80 isolates of Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBLs) were collected from infected patients in our hospital. Enterobacter aerogenes was the most common bacterium isolated from all specimens (36.5%). The ESBLs were predominantly (90%) TEM derivatives (TEM-24, TEM-3). Pulsed-field gel electrophoresis highlighted that E. aerogenes, Klebsiella pneumoniae, and Citrobacter koseri had a clonal propagation.

Enterobacteriaceae↗
PubMed2005

Countrywide spread of community- and hospital-acquired extended-spectrum beta-lactamase (CTX-M-15)-producing Enterobacteriaceae in Lebanon.

A prospective study was carried out to assess the extent of carriage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae at both hospital and community levels in Lebanon. A total of 1,442 fecal samples were collected from hospital-based patients and 58 from health care workers of six Lebanese tertiary care general hospitals located in different areas of Lebanon between January and March 2003. A total of 382 fecal samples were also collected from healthy subjects between April and June 2003. The samples analysis led to the identification of 118 strains as ESBL producers based on the synergistic effects between clavulanate and selected beta-lactams (ceftazidime and cefotaxime). These strains were isolated from 72 subjects: 61 patients, 2 health care workers, and 9 healthy subjects. One representative strain per subject was selected, and a total of 72 nonduplicate ESBL producers, including a high majority of Escherichia coli (n = 56), Klebsiella pneumoniae (n = 9), Enterobacter cloacae (n = 6), and Citrobacter freundii (n = 1), were characterized. The molecular analysis revealed that the majority of the strains (83%) express CTX-M-15 ESBL (pI 8.6). SHV-5a ESBL (pI 8.2) was produced by 18% of the strains. DNA macrorestriction analysis of ESBL-producing E. coli presented 38 different genotypes, revealing the absence of clonal link among these strains. In addition to the fact that the present study highlights the emergence and the countrywide dissemination of CTX-M-15-producing E. coli in Lebanon, it represents the first report of an SHV-5a-producing C. freundii.

Anti-Bacterial Agents↗
PubMed1978

Evaluation of the Repliscan system for identification of Enterobacteriaceae.

The Repliscan system, a semiautomated method for identifying gram-negative bacilli, was evaluated for its potential usefulness in clinical microbiology laboratories. A total of 1,877 isolates, including 1,712 fermentative and 165 nonfermentative organisms, were tested in parallel with the Repliscan and Enterotube methods of enteric identification. Discrepancies were retested in each system as well as with conventional methods. The Repliscan method correctly identified 91%, misidentified 2%, and failed to identify 7% of the fermentative orgamisms tested. Of the genera under study, Enterobacter posed the greatest problem to the system in terms of overall identification rates. The Repliscan appears to be an efficient, economic, and effective laboratory tool for identification of Enterobacteriaceae.

Anti-Bacterial Agents↗
PubMed1979

Comparison of Micro-ID and API 20E systems for identification of Enterobacteriaceae.

The Micro-ID 4-h identification system for Enterobacteriaceae was compared to the API 20E overnight method, using 230 fresh clinical isolates and 74 stock cultures. Agreement was 97.8% for the clinical isolates and 93.2% for the stock cultures. Eighty-seven percent of primary culture plates containing gram-negative rods yielded sufficient growth to perform the 4-h Micro-ID identification on the same day the organisms were isolated.

Bacteriological Techniques↗
PubMed1976

A comparison of two commerical methods for the identification of the Enterobacteriaceae--API 20E and the Enterotube--with conventional methods.

The API 20E, the Enterotube, and routine methods of Cowan and Steel were used in parallel to identify 245 members of the Enterobacteriaceae. The API 20E and conventional methods gave the same identification in all but 2 (0-8%) of the 245 organisms tested. The Enterotube correctly identified 85% of these organisms on the first testing. On re-testing those organisms incorrectly identified the Enterotube results agreed with the conventional ones in a further 20 (8%). There was no change in the identification obtained by the API or conventional methods. Further conventional sugar tests were necessary before final identification was available by the API system in 7 (3%) against 106 (47%) of the 226 organisms correctly identified by the Enterotube. The Enterotube relied on serological testing alone to distinguish between alternatives in 17 (7%) isolates. Other advantages and disadvantages of these systems are discussed.

Bacteriological Techniques↗
PubMed1975

Functional role of antibody against "core" glycolipid of Enterobacteriaceae.

Antibodies against the "core" glycolipid of Enterobacteriaceae (2-keto, 3-deoxyoctonate-Lipid A) have been associated with protection against the sequelae of gram-negative rod bacteremia. To investigate the nature of this protection, dogs and rabbits were immunized with purified glycolipid prepared by phenol-chloroform-petroleum ether extraction of the "Re" mutant of Salmonella minnesota 595 and opsonophagocytic and bactericidal tests were carried out using lapine peritoneal granulocytes and serum factors. Whereas 1-4 mug/kg of glycolipid i.v. produced hypotension in dogs and 8 mug/kg i.v. was lethal, a rising dosage schedule of immunization with an average total dose of 1 mg/kg produced striking protection against shock and death against challenge with heterologous organisms. 20 control dogs, given approximately 10(10) live, serum-resistant Escherichia coli 0.85:H9 or Serratia marcescens 03 during a continuous intra-arterial pressure transducer recording, showed a drop in mean systolic pressure from 186 (+/- 6 SE) to 101 (+/- 12 SE) MM Hg and a fall in mean diastolic pressure from 118 (+/- 3 SE) to 64 (+/- 8 SE) mm Hg within 60-120 min. Minor pressure changes (average less than 12% of prechallenge levels) were seen in the same number of immunized dogs. In contrast, no significant difference was noted in the bloodstream clearance of these serum-resistant organisms over a period of 4-6 h between immunized and control dogs. Intravascular clearance was greater in animals immunized with the challenged strain or in glycolipid-immunized animals challenged with highly serum-sensitive E. coli 0.14:K7. Antibody against core glycolipid protected against the hemodynamic sequelae of bacillemia, augmented intravascular clearance of serum-sensitive organisms, and abrogated the pyrogenic response to enteric bacilli, but did not enhance clearance of serum-resistant organisms. Although canine and lapine antiserum against core glycolipid passively protected mice against a heterologous challenge, opsonophagocytic and bactericidal activity was at least 100-fold less than type-specific antiserum.

Animals↗
PubMedDate not supplied

Comparative in vitro activity of temocillin and other antimicrobial agents against Enterobacteriaceae isolated from patients admitted to five Belgian hospitals.

Temocillin, a methoxy-derivative of the broad-spectrum penicillin, ticarcillin, has been introduced into clinical practice in Belgium in 1988. Since then, not many surveys of its in vitro activity have been published. This study addresses this issue in a prospective collection of 300 consecutive Gram-negative isolates originating from in-patients in five general hospitals throughout Belgium. In addition to temocillin, seven common antibiotics were tested: amoxicillin-clavulanate, piperacillin-tazobactam, cefotaxime, aztreonam, meropenem, ciprofloxacin and amikacin. Meropenem appeared to exhibit the best activity overall, whereas amoxicillin-clavulanate scored the worst. Cumulative MIC plot for two subsets of organisms are given: temocillin, meropenem and cefotaxime are the most active on E. coli and Klebsiella spp., while a significant percentage is resistant to ciprofloxacin and amoxicillin-clavulanate. In the group of inducible Enterobacteriaceae, temocillin, meropenem and amikacin are the most active drugs, while the activity of amoxicillin-clavulanate, piperacillin-tazobactam, cefotaxime and ciprofloxacin is largely decreased. Taking this well preserved in vitro activity of temocillin into account, and looking at its convenient pharmacokinetics and low cost of acquisition, this drug may prove a useful alternative in the treatment of severe nosocomial infections.

Anti-Bacterial Agents↗
PubMed2003

Central venous catheter removal versus in situ treatment in neonates with enterobacteriaceae bacteremia.

OBJECTIVE: To determine how often neonates with Enterobacteriaceae (ENTB) bacteremia can be treated successfully without removing central venous catheters (CVCs). METHODS: A retrospective cohort study was conducted of ENTB bacteremia and CVCs in infants in a neonatal intensive care unit during a 7-year period (1994-2000). Cases of ENTB bacteremia were identified from a microbiology database and limited to late-onset cases occurring after 3 days of age. RESULTS: There were 53 cases of ENTB bacteremia in infants with CVCs. Blood cultures were positive for ENTB within a median of 10 hours (range: 5-43). Timing of CVC removal was at the discretion of attending neonatologists. Fifteen cases had early-removal CVC (ER-CVC) within 2 days, and 38 cases had late-removal CVC (LR-CVC) >2 days after the first positive blood culture for ENTB. There were no significant differences between infants in the ER-CVC and LR-CVC groups for case fatality, recurrence, or duration of ENTB bacteremia. Although 16 (42%) of 38 (95% confidence interval [CI]: 26%-59%) LR-CVC cases required CVC removal to resolve ENTB bacteremia, 17 (45%) of 38 (95% CI: 29%-62%) LR-CVC cases were treated successfully without removal of CVCs. ENTB bacteremia was successfully treated without CVC removal in 85% of 13 LR-CVC cases with 1 day of bacteremia in contrast to 24% of 25 LR-CVC cases with >1 day of bacteremia (relative risk: 3.5; 95% CI: 1.7-7.4). CVC removal was required to resolve ENTB bacteremia in 9 (82%) of 11 LR-CVC cases with severe thrombocytopenia compared with 7 (32%) of 22 LR-CVC cases without severe thrombocytopenia (relative risk: 2.6; 95% CI: 1.3-5.0). CONCLUSIONS: Retention of CVCs was successful in 45% of cases of ENTB bacteremia in which it was attempted, but success was unlikely when bacteremia lasted >1 day. ENTB bacteremia cases associated with severe thrombocytopenia rarely resolved unless CVCs were removed.

Aminoglycosides↗
PubMed2003

Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae: considerations for diagnosis, prevention and drug treatment.

Extended spectrum beta-lactamase (ESBL)-producing organisms pose unique challenges to clinical microbiologists, clinicians, infection control professionals and antibacterial-discovery scientists. ESBLs are enzymes capable of hydrolysing penicillins, broad-spectrum cephalosporins and monobactams, and are generally derived from TEM and SHV-type enzymes. ESBLs are often located on plasmids that are transferable from strain to strain and between bacterial species. Although the prevalence of ESBLs is not known, it is clearly increasing, and in many parts of the world 10-40% of strains of Escherichia coli and Klebsiella pneumoniae express ESBLs. ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infection throughout the world and pose challenging infection control issues. Clinical outcomes data indicate that ESBLs are clinically significant and, when detected, indicate the need for the use of appropriate antibacterial agents. Unfortunately, the laboratory detection of ESBLs can be complex and, at times, misleading. Antibacterial choice is often complicated by multi-resistance. Many ESBL-producing organisms also express AmpC beta-lactamases and may be co-transferred with plasmids mediating aminoglycoside resistance. In addition, there is an increasing association between ESBL production and fluoroquinolone resistance. Although in in vitro tests ESBLs are inhibited by beta-lactamase inhibitors such as clavulanic acid, the activity of beta-lactam/beta-lactamase inhibitor combination agents is influenced by the bacterial inoculum, dose administration regimen and specific type of ESBL present. Currently, carbapenems are regarded as the drugs of choice for treatment of infections caused by ESBL-producing organisms. Unfortunately, use of carbapenems has been associated with the emergence of carbapenem-resistant bacterial species such as Stenotrophomonas sp. or Pseudomonas sp.

Anti-Bacterial Agents↗
PubMed1981

Epidemiologic features of urinary infections due to enterobacteriaceae resistant to nalidixic acid and trimethoprim.

For a period of one year we identified all urinary isolates of Enterobacteriaceae resistant to either nalidixic acid (NA) or trimethoprim (TMP). Host and organism characteristics associated with the occurrence of 68 NA and 61 TMP-resistant isolates were compared with 61 matched antimicrobial-susceptible controls. Minimum inhibitory concentrations to NA and TMP were carried out on all isolates, Escherichia coli isolates were biotyped and TMP-sulfamethoxazole (SMX) synergy studies were performed on TMP-resistant isolates. Study patients were reviewed with regard to age, renal function, presence of structural urinary tract abnormality, history of antimicrobial treatment and persistence of study strains within the urinary tract. Resistance to both drugs was associated with prior treatment with the relevant antimicrobial and with underlying urinary tract abnormality. No association was noted between resistance and patient age or renal function. Once resistant organisms infected an abnormal urinary tract, they were able to persist almost indefinitely. Patients with persistent urinary infections associated with structural urinary tract abnormality account for most NA or TMP-resistant infections in our hospital and constitute an identifiable group in whom the therapeutic usefulness of these drugs is limited.

Adult↗
PubMed1998

The characteristics of extended-spectrum beta-lactamases in Korean isolates of Enterobacteriaceae.

Extended-spectrum beta-lactamases (ESBLs) in gram-negative organisms have been implicated as the enzymes responsible for resistance to oxyimino-cephalosporins. The incidence of ESBL-producers in Korean isolates of Escherichia coli and Klebsiella pneumoniae were in the range of 4.8-7.5% and 22.5-22.8%, respectively. The ESBL-producing isolates revealed variable levels of resistance to cefotaxime, ceftazidime and aztreonam. They also showed the elevated MIC values of non-beta-lactam antibiotics. SHV-12 and SHV-2a were the enzymes most frequently found in K. pneumoniae strains, but TEM-52 was the most prevalent in E. coli isolates. About 15% of ESBL-producing isolates of Enterobacteriaceae produced CMY-1 enzyme, which conferred resistance to cephamycins such as cefoxitin as well as oxyimino-cephalosporins. Thus, the most common types of ESBLs in Korea are TEM-52, SHV-12 SHV-2a, and CMY-1.

Drug Resistance, Microbial↗
PubMed2002

Extended-spectrum beta-lactamases in Enterobacteriaceae: related to age and gender.

The prevalence of extended-spectrum beta-lactamases producing Enterobacteriaceae (ESBLPE) among nosocomial and community acquired isolates was studied (September, 1999 - August, 2000). Nosocomial and OPD isolates (200 each) were collected from OPD and different wards of the Pakistan Institute of Medical Sciences (PIMS) Islamabad, Pakistan, and tested for the production of ESBLs using the double disc diffusion technique. The prevalence of ESBL was highest in nosocomial isolates among the patients of age group III (50-60 years) (48%) with Escherichia coli as the most prevalent organism. ESBL positive isolates were mostly reported in males (65.33%) compared to females (34.67%).

Adult↗
PubMed2003

Antimicrobial resistance of animal and human strains of Enterobacteriaceae in Greece.

Two hundred sixty two strains of Enterobacteriaceae from animal and human sources where intermixing and/or spreading is possible were examined for their resistance to 15 antimicrobials frequently used in animal prophylaxis and metaphylaxis. The antimicrobials with the highest proportion of resistant strains from animal sources were amoxicillin 25 mg, colistin sulphate 25 mg, erythromycin 5 mg, penicillin G 10 mg and spectinomycin 10 mg. The same with isolates from human sources where ampicillin 10 mg, amoxicillin 25 mg, colistin sulphate 25 mg, erythromycin 5 mg, neomycin 10 mg, penicillin G 10 mg and spectinomycin 10 mg. Human isolates were resistant to more antimicrobials than animal isolates. Common a high proportion of isolates from both sources were resistant to some antimicrobials. Systematic and better distributed information is needed to address the epidemiological role of veterinary treatment, prophylaxis and metaphylaxis in antimicrobial resistance in Greece.

Animals↗
PubMed2000

The mechanism of ampicillin resistance in enterobacteriaceae isolated in Vellore.

Ampicillin resistance in clinical isolates of enterobacteriaceae has been on the increase in the last decade. A study was carried out to delineate the possible mechanisms of this resistance. The method employed was isoelectric focussing to observe the electrophoretic mobility of the enzyme responsible and this showed that TEM 1 betalactamase was the cause irrespective of the species.

Ampicillin Resistance↗
PubMed2003

Prevalence of extended-spectrum beta-lactamases produced by nosocomial isolates of Enterobacteriaceae in Trakya University Hospital, Turkey.

The prevalence of extended-spectrum beta-lactamase (ESBL) production by 194 nosocomial isolates of Enterobacteriacea recovered from 1995 to 1999 was investigated. The ESBL production was determined by the double-disk synergy test and was confirmed by the E-test ESBL strip. Twenty-three isolates (21 Klebsiella pneumoniae, one Escherichia coli, one Providencia rettgeri) were found as ESBL-producers (11.8%). These isolates were also usually resistant to non-betalactam antibiotics. Most of them contained a beta-lactamase with a pI of 7.6. All the strains conjugally transferred their ESBLs to recipient E. coli. Contrary to others, ESBL-producing K. pneumoniae strains isolated in 1999 were resistant to ciprofloxacin, and had the identical plasmid profiles suggestive of an outbreak. Ciprofloxacin resistance in these strains could not be transferred. In conclusion, K. pneumoniae was the main ESBL-producing species among nosocomial isolates of Enterobacteriacae in our hospital.

Conjugation, Genetic↗
PubMedDate not supplied

Resistance pattern of extended-spectrum beta-lactamase producing Enterobacteriaceae isolates.

Gram-negative pathogens harboring extended-spectrum beta-lactamases (ESBL) are becoming an increasing therapeutic problem in many wards. The aim of our work was to study ESBL production by Enterobacteriaceae strains from Eastern Romania and their antimicrobial resistance. We selected 54 clinical isolates among 1068 enterobacteria according to their susceptibility spectrum (National Committee for Clinical Laboratory Standards, 1999). Antimicrobial susceptibility tests were performed using the Rapid ATB E gallery of mini API system (BioMérieux) and by a macrodilution method in Mueller-Hinton agar following standard procedure of the National Committee for Clinical Laboratory Standards (NCCLS). ESBL production was established by using both double disk synergy test (DDT) and Expert computer program of mini API. The isoelectric point (pI) was determined by isoelectric focusing in polyacrylamide gel and revealed by nitrocefin. As references we used beta-lactamases with known pI. The Expert computer program of mini API confirms the positive DDT test for all selected strains. Almost all strains displayed resistance to ampicillin, ampicillin/sulbactam or third generation cephalosporins and aztreonam. By IEF we identified 51 strains which have a unique enzyme. IEF pattern showed presence of two enzymes in three Escherichia coli strains. According to our results, the ESBL TEM-type are the most common for the studied isolates. The production of extended-spectrum beta-lactamases and the presence of the multiresistant of antimicrobial agents reflect, probably, the over use of third generation cephalosporins in Eastern Romania.

Drug Resistance, Bacterial↗