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PubMed1987

In vitro activity of cefixime and six other agents against nosocomial pathogens of the Enterobacteriaceae family.

Cefixime, a broad-spectrum, orally active cephalosporin, was more active in vitro than ampicillin, cefaclor, cephalothin, and trimethoprim/sulfamethoxazole against 194 nosocomial pathogens of the family Enterobacteriaceae. Activity was especially good against Klebsiella spp, Proteus spp, Serratia spp, and Providencia stuartii. Although gentamicin had equivalent or better activity against Citrobacter spp, Enterobacter spp, Escherichia coli, and Morganella morganii, all 23 of the gentamicin-resistant strains studied were susceptible to cefixime. Isolates tested were from urinary tract infections, abdominal infections, wounds, vascular infections, and respiratory infections; they were sequentially collected nosocomial pathogens from a single institution. This orally active cephalosporin should be considered for therapy of a variety of nosocomial infections involving gram-negative bacillary pathogens.

Ampicillin↗
PubMed2003

Evaluation of VITEK 2 for analysis of Enterobacteriaceae using the Advanced Expert System (AES) versus interpretive susceptibility guidelines used at Dynacare Kasper Medical Laboratories, Edmonton, Alberta.

OBJECTIVE: To evaluate the applicability and adaptability of the bioMérieux VITEK 2 Advanced Expert System (AES) to the customized interpretive susceptibility guidelines used at Dynacare Kasper Medical Laboratories (DKML). METHODS: Three hundred isolates of Enterobacteriaceae (not more than 30% Escherichia coli) were tested on the VITEK 2 system and the API 20E for identification. Susceptibility testing for these isolates was performed on the VITEK 2 system and the Pasco broth microdilution panels. Minimal inhibitory concentrations (MICs) and interpreted results according to the AES and DKML antimicrobial susceptibility guidelines were compared. RESULTS: Of 300 isolates tested for susceptibility, 13 did not give AES interpretations. Of the remaining 287 isolates, interpretations between AES and DKML guidelines were compared for 10 antibiotics. The overall correlation between the AES and DKML interpretations was 96.2%. CONCLUSION: This study demonstrated the benefits and limitations of the bioMérieux AES. Automated knowledge-based systems provide a useful laboratory tool for the interpretation of susceptibility results.

Alberta↗
PubMed1994

Genetic and molecular R-plasmid analysis of Enterobacteriaceae hospital strains at Children's Hospitals of the former USSR.

R-plasmids from Enterobacteriaceae clinical strains, mainly Klebsiella and Serratia, isolated at different neonatal and children's hospitals of different cities of the former USSR for 10 years, were studied for their possible influence on the bacterial host phenotype. Hospital R-plasmids of stable inheritance persisted in hospitals from 2 to 7 years and were disseminated among strains of different genera (Klebsiella, Serratia, Enterobacter) and among different units. The data showed a possibility of long-term molecular rearrangements of R-plasmids in the hospital settings and an acquisition of genetic determinants encoding enterotoxin production. A novel R-plasmid encoding cytotoxicity to HEp-2 cells involved in two nosocomial outbreaks due to K. pneumoniae strains was reported. K. pneumoniae population heterogeneity was evaluated by using the plasmid parameters of strains. Their heterogeneity of a bacterial population was significantly lower during nosocomial outbreaks than in interepidemic periods.

Base Sequence↗
PubMed1999

Control of a prolonged outbreak of extended-spectrum beta-lactamase-producing enterobacteriaceae in a university hospital.

Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBLPE) were isolated from clinical specimens from 130 to 140 patients/year in 1989-1991 in our hospital. In February 1992, a control program was initiated: screening tests in 3 intensive care units (ICUs) and contact-isolation precautions in all units. The septic surgical unit served as an isolation ward for surgical patients from whom ESBLPE was isolated. In 1992, the incidence of ESBLPE acquisition failed to decrease, and most acquisitions occurred in 3 ICUs. Critical evaluation of implementation of isolation procedures in these ICUs prompted corrective measures for barrier precautions. The incidence of acquired cases subsequently decreased, and a second evaluation determined that these measures had been correctly applied. The incidence of acquired cases in the septic surgical unit was lower than those in the other units. Decreases were also found in the incidence of acquisition of other hand-transmitted multidrug-resistant organisms. Barrier precautions, screening tests for ICU patients, and grouping of cohorts after ICU discharge are effective in controlling the spread of multidrug-resistant microorganisms by cross-contamination. The outbreak was effectively controlled without restricting antimicrobial use.

Anti-Bacterial Agents↗
PubMed2002

Is surveillance for multidrug-resistant enterobacteriaceae an effective infection control strategy in the absence of an outbreak?

Multidrug-resistant enterobacteriaceae (MDRE) are an important cause of nosocomial infections. The effectiveness of screening for MDRE in the nonoutbreak setting in an attempt to prevent transmission is unknown. Patients admitted for new organ transplantation were screened for MDRE colonization. Prospective clinical data were collected, and pulsed-field gel electrophoresis and plasmid and integron analysis of isolates were performed. Colonized patients were not isolated except when required by standard precautions. Of the 287 patients, 69 (24%) were colonized, and 6 (9%) of the 69 developed clinical infections. Most colonizing isolates (66/69) were unique. No clinical infections resulted from patient-to-patient transmission. Analysis of clinical isolates from nonstudy patients demonstrated no evidence of transmission leading to clinical disease. The annual cost of a surveillance program was calculated at Canadian $1,130,184.44. Thus, the routine and costly use of MDRE surveillance and isolation precautions are not warranted in the absence of a clonal outbreak in this population.

Anti-Bacterial Agents↗
PubMed1998

Infection in the intensive care unit: beta-lactamase-mediated resistance among Enterobacteriaceae and optimal antimicrobial dosing.

Class I beta-lactamase-mediated resistance in Enterobacteriaceae is increasingly common, clinically important, and often associated with previous use of third-generation cephalosporins. Extended-spectrum beta-lactamases that confer resistance to third-generation cephalosporins are also becoming more widespread. Beta-lactamase-producing organisms often display multiresistance, and this has been associated with increased mortality among patients. For all beta-lactam antimicrobials, the time that the plasma concentration exceeds the minimum inhibitory concentration (MIC) is the principal factor determining antibacterial activity. For concentration-dependent antimicrobials such as aminoglycosides and fluoroquinolones, the area under the plasma-concentration time curve:MIC ratio is the variable that has the strongest link to clinical outcome, particularly when relatively low peak: MIC values (< 10:1) are achieved. Peak concentration is of major concern for suppression of resistance. When high peak: MIC ratios (> or = 10:1) are achieved, this may suppress resistance and become the primary variable linked to outcome. When designing antimicrobial dosage regimens, it is important to take into account the pharmacodynamics of the drug in order to maximize the potential for achieving a positive clinical outcome and suppressing the emergence of bacterial resistance.

Animals↗
PubMed2006

Occurrence of extended spectrum beta-lactamases among isolates of Enterobacteriaceae from urinary tract infections in southern Italy.

The present investigation was undertaken to assess the prevalence of extended-spectrum beta-lactamases (ESbetaLs) among urinary tract infection (UTI) isolates. During 4 months in 2004, a total of 650 Enterobacteriaceae strains from UTIs was collected by five clinical microbiology laboratories located in southern Italy and the beta-lactamase production was investigated. A total of 50 of the 650 isolates were double-disk positive and suspected of producing an ESbetaL; Escherichia coli (36.0%) and Klebsiella pneumoniae (32.0%) were the most common species among all ESbetaL producers. Characterization of ESbetaL determinants was carried out by the colony blot hybridization method, and polymerase chain reaction (PCR) and DNA sequencing in order to identify the presence of bla (TEM), bla (SHV), bla (PER), and bla (CTX-M) determinants. The ESbetaL variants found in this study were the following: TEM-15, TEM-24, TEM-52, TEM-134, SHV-12, CTX-M-1, CTX-M-3, CTX-M-15, and PER-1. As expected, the majority of the isolates were found to be susceptible to imipenem (94%), cefepime (54%) and piperacillin-tazobactam (54%). The results of this survey show the prevalence of ESbetaL enzymes among enterobacterial pathogens causing UTIs in southern Italy.

Anti-Bacterial Agents↗
PubMed1980

A biotype of Enterobacteriaceae intermediate between Citrobacter and Enterobacter.

The authors isolated two strains of an unnamed bacterial biotype with characteristics intermediate between those of Enterobacter and Citrobacter. The organisms did not produce acetyl-methyl carbinol, but decarboxylated lysine. Apart from the latter trait, they most closely resemble H2S-negative Citrobacter freundii. They differ biochemically from all other currently accepted species of enterobacteriaceae. Their pathogenic significance appears similar to that of the two genera they most closely resemble. Only by recognition and study of additional strains can their identity be more definitively delineated and their significance more fully assessed.

Child↗
PubMedDate not supplied

Klebsiella pneumoniae and other Enterobacteriaceae producing novel plasmid-mediated beta-lactamases markedly active against third-generation cephalosporins: epidemiologic studies.

Analysis of the enzymes produced by clinical isolates of multiresistant Klebsiella pneumoniae from hospitals in France revealed two novel broad-spectrum beta-lactamases. The first, characterized by an isoelectric point of 6.3 and a high hydrolytic activity on cefotaxime, is designated CTX-1. This beta-lactamase was encoded by a 95-kilobase plasmid (incompatibility group 7M) and cotransferred with resistance to tetracyclines, sulfonamides, and aminoglycosides (AAC [6']-IV). From 1984 to June 1987, 490 CTX-1-producing strains of Enterobacteriaceae were isolated. The second plasmid-mediated beta-lactamase (CAZ-1) was isolated in 1987 from three K. pneumoniae strains more resistant to ceftazidime than to other third-generation cephalosporins. This broad-spectrum beta-lactamase differed from CTX-1 by its isoelectric point--close to 5.6--and its high hydrolytic activity on ceftazidime and was encoded by a 150-kilobase plasmid. It was demonstrated that these expanded-spectrum beta-lactamases are TEM derivatives.

Cephalosporins↗
PubMedDate not supplied

Extended broad-spectrum beta-lactamases conferring transferable resistance to newer beta-lactam agents in Enterobacteriaceae: hospital prevalence and susceptibility patterns.

Before 1985 at the Pitié-Salpêtrière Hospital in Paris (2,400 beds), resistance to cefotaxime in clinical isolates of Enterobacteriaceae involved only species producing inducible class 1 beta-lactamase. Between November 1985 and April 1987, however, 62 isolates (57 of Klebsiella pneumoniae and five of Escherichia coli) showed decreased susceptibility to cefotaxime (mean MIC, 8-16 micrograms/mL). The transferability of cefotaxime resistance in E. coli K12 was demonstrated for 15 of 16 selected isolates. By isoelectric focusing using iodometric detection with 20 mg of ceftriaxone/100 mL and determination of substrate and inhibition profiles, three beta-lactamases mediating cefotaxime resistance were identified as SHV-2 (isoelectric point [pI] 7.6), CTX-1 (pI 6.3), and "SHV-2-type" or SHV-3 (pI 6.98). The three beta-lactamases hydrolyzed penicillins and cephalosporins (including cefotaxime and ceftriaxone) and were therefore designated "extended broad-spectrum beta-lactamases" (EBS-Bla). The enzymes conferred to derivatives a high level of resistance to amoxicillin, ticarcillin, piperacillin, and cephalothin and a decreased degree of susceptibility (i.e., MICs increased by 10- to 800-fold) to cefotaxime, ceftriaxone, ceftazidime, and aztreonam. These beta-lactamases did not affect the activity of cephamycins (cefoxitin, cefotetan, moxalactam) or imipenem. Synergy between clavulanate or sulbactam (2 micrograms/mL) and amoxicillin was greater against derivatives producing EBS-Bla than against those producing TEM-1, TEM-2, or SHV-1; this synergy was greater with clavulanate than with sulbactam against derivatives producing SHV-2 and the SHV-2-type enzyme but was similar with clavulanate and sulbactam against those producing CTX-1. A double-disk synergy test performed with cefotaxime and Augmentin disks (placed 30 mm apart, center to center) seemed a useful and specific test for the detection of strains producing EBS-Bla.

Anti-Bacterial Agents↗
PubMed1996

Outbreak of multiply resistant enterobacteriaceae in an intensive care unit: epidemiology and risk factors for acquisition.

A prospective study was initiated in an intensive care unit (ICU) where extended-spectrum beta-lactamase-producing enterobacteriaceae (ESBLPE) were endemic. From July 1990 to July 1991, patients hospitalized for > or = 5 days were screened for ESBLPE acquisition by means of weekly rectal sampling and clinical cultures. Baseline characteristics and various ICU procedures in 62 cases of ESBLPE were compared with those for 205 patients without ESBLPE, with use of Cox's model. Risk for acquiring ESBLPE (Klebsiella pneumoniae in most cases) increased during the ICU stay, from 4.2% in the first week to 24% in the fourth week. Baseline characteristics were not different between the two groups. Urinary catheterization (P = .04) and arterial catheterization (P = .03) were independent risk factors for acquiring ESBLPE and probably reflected frequency of health care manipulations. The first site of ESBLPE acquisition was the digestive tract in 58 of the 62 patients; 28 infections developed in 22 patients, and these followed or occurred simultaneously with rectal colonization in 18 of those 22. DNA macrorestriction analysis suggested that the same strain was responsible for most cases. In conclusion, ESBLPE acquisition depends on length of stay in the ICU and the use of invasive procedures. Colonization is a prerequisite for infection.

Adult↗
PubMedDate not supplied

Influence of imipenem on the serum resistance of enterobacteriaceae.

Following growth in a subinhibitory concentration of imipenem and additional incubation in a 20% dilution of normal human serum (NHS) for 90 minutes, five of 12 serum-resistant strains of enterobacteriaceae showed a decrease in colony-forming units of two or more logs of growth compared with the control. Two strains (of Escherichia coli and Enterobacter aerogenes) showed this phenomenon even with incubation in 5% NHS. Treatment with imipenem did not change the serum resistance of the other seven strains (two strains each of Enterobacter cloacae, Klebsiella pneumonia, and Serratia marcescens, and one strain of Proteus morganii). The phenomenon of induced serum susceptibility is dose dependent and reversible. Other beta-lactam antibiotics either caused only a slight decrease of resistance (cefsulodin, cefoxitin, cefuroxime, cefodizime-HR221) or did not influence the serum resistance at all (cefotaxime, mecillinam). Killing of the induced serum-sensitive strains appeared to be antibody dependent.

Anti-Bacterial Agents↗
PubMed1985

In-vitro activity of the monobactam Ro 17-2301 against clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa.

Ro 17-2301 is a monobactam antibiotic. Its in-vitro activity was compared with those of aztreonam, ampicillin, cefuroxime, ceftriaxone, ceftazidime, and gentamicin. Ro 17-2301 had qualitatively similar activity to aztreonam and activity superior to that all the other antibiotics against the Enterobacteriaceae, but against Pseudomonas aeruginosa ceftazidime had equal or marginally better activity.

Anti-Bacterial Agents↗
PubMed1987

Aminoglycoside resistance patterns in clinical isolates of Enterobacteriaceae from Czechoslovakia.

Multi-resistant Enterobacteriaceae isolated mainly from urine specimens from patients at the Department of Urology, Kramáre Hospital, Bratislava, were characterized for resistance phenotype. Seventeen gentamicin-resistant isolates were further studied for the presence of aminoglycoside-modifying enzymes. Five enzymes were detected: AAC(2'), AAC(3)-II, AAC non-characterized, ANT(2") and APH(3')-I. The substrate range of these enzymes was found to correlate with the resistance phenotype in most isolates. In our collection the AAC(3)-II enzyme that inactivates gentamicin, sisomicin, tobramycin and netilmicin was predominant. Predominance of this type of modifying enzyme has been observed also in resistant Gram-negative strains in Belgium, The Netherlands and Chile, in contrast to the United States, Federal Republic of Germany, Switzerland, Greece and Turkey, where ANT(2") has been the most common enzyme.

Acetyltransferases↗
PubMed1989

Comparative in-vitro activity of meropenem against clinical isolates including Enterobacteriaceae with expanded-spectrum beta-lactamases.

Meropenem, a new parenteral carbapenem, was tested in vitro by an agar-dilution method against 373 standard strains (aerobes and anaerobes) and against nine expanded-spectrum beta-lactamase-producing strains and their transconjugants (5 CTX-1, 2 CAZ-1, 2 CAZ-2). Meropenem was compared with methicillin, imipenem, piperacillin, cefoxitin, cefotaxime, ceftazidime, gentamicin, chloramphenicol, clindamycin, ciprofloxacin, vancomycin and metronidazole. Meropenem and imipenem exhibited an extended spectrum of activity, with low MICs. Only methicillin-resistant staphylococci, and Pseudomonas (Xanthomonas) maltophilia were resistant. Of the carbapenems, imipenem was more active against methicillin-susceptible staphylococci, streptococci and Enterococcus faecalis, but meropenem was markedly more active against all the Enterobacteriaceae and some pseudomonads. Both had similar activity against Ps. aeruginosa, Acinetobacter spp. and anaerobes. The carbapenem MICs were very low for Enterol acteriaceae producing the expanded-spectrum beta-lactamases. Against CTX-1-producing strains resistant to cefotaxime and ceftazidime and against CAZ-1 or CAZ-2-producers highly resistant to ceftazidime meropenem was the most active, with MICs lower (0.03-0.12 mg/l) than those of imipenem (0.06-0.5 mg/l), for wild type producers and their transconjugants.

Bacteria↗
PubMed2006

Identification and characterization of ceftriaxone resistance and extended-spectrum beta-lactamases in Malawian bacteraemic Enterobacteriaceae.

OBJECTIVES: To enumerate and characterize extended-spectrum beta-lactamases (ESBLs) amongst ceftriaxone-resistant coliforms in Blantyre, Malawi, where third-generation cephalosporin use is currently highly restricted. METHODS: Over the period April 2004-March 2005 all ceftriaxone-resistant isolates from blood cultures were examined for the presence of ESBLs. Isoelectric focusing was performed on enzyme extracts. PCR and DNA sequencing of amplicons were used to identify the underlying genetic determinants responsible for the ESBL phenotypes. Transferability of the ESBL phenotypes was tested by conjugation to a susceptible Escherichia coli J53. RESULTS: Enterobacteriaceae were isolated from 1191 blood cultures, of which 19 (1.6%) were ceftriaxone resistant. Ten isolates (0.7% of all isolates) demonstrated an ESBL phenotype but only eight were characterized as three isolates were from the same patient. Genotypes SHV-11 (n = 1), SHV-12 (n = 3), SHV-27 (n = 1), TEM-63 (n = 2) and CTX-M-15 (n = 1) were detected. Plasmid transfer of the ESBL resistance phenotype was successful for all the isolates. CONCLUSIONS: In a clinical setting of minimal cephalosporin usage there is already a diversity of ESBL genotypes. Increased use of cephalosporins in this setting is likely to result in a rapid expansion of ESBLs and their prevalence will need to be carefully monitored.

Adult↗
PubMedDate not supplied

Selective inhibition of enterobacteriaceae in fecal flora of children by oral trimethoprim-sulfamethoxazole.

Fecal flora of nine pediatric inpatients who were receiving trimethoprim-sulfamethoxazole were studied by quantitative aerobic and anaerobic culture methods. During the course of trimethoprim-sulfamethoxazole, the number of Enterobacteriaceae decreased from 10(8-9) to 10(4-5) bacteria per g feces. The isolation rate and the number of Veillonella were also reduced. Other prominent aerobic and anaerobic flora, including Streptococcus, Bacteroidaceae and Bifidobacterium, were not affected. No overgrowth of Pseudomonas, Staphylococcus, Candida or Clostridium was noted. These results support the usefulness of oral trimethoprim-sulfamethoxazole for the prophylaxis of bacterial infection in the compromised host.

Child↗