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PubMed1996

The origin, by mutation, of high level resistance to ceftazidime and cefotaxime in a clinical isolate of Enterobacter cloacae.

Although strains of Enterobacter sp. produce a chromosomal AmpC beta-lactamase, they have been, in general, susceptible to cefotaxime or ceftazidime. But now resistance to ceftazidime has increased in nosocomial Enterobacter strains, reaching the level of 40%. A chromosomal mutation in the amp operon coding the production of AmpC type beta-lactamase may cause a change in the conversion of a susceptible strain of Enterobacter to a highly resistant mutant. The production of AmpC enzyme is inducible and third-generation cephalosporins are weak inducers of AmpC production. Spontaneous mutations (or insertions of transposons) in the regulatory region of amp operon might create constitutive (derepressed) overproducers of large amounts of AmpC molecules. As a consequence, such cells acquire a stable resistance to beta-lactam antibiotics including cefotaxime or ceftazidime. We describe the origin of mutants of a clinical isolate of Enterobacter cloacae that acquired high-level resistance to ceftazidime followed by the resistance to cefotaxime and/or aztreonam due to a second mutation.

Aztreonam↗

PubMed1992

Enterobacter endocarditis.

Endocarditis due to Enterobacter species is very rare. We recently cared for a patient who developed E. cloacae endocarditis following mitral valve replacement with a porcine heterograft, and was successfully treated with antibiotic therapy alone. A review of the literature disclosed an additional 17 well-described cases of enterobacter endocarditis. Two-thirds of the patients had underlying cardiac disease. The mitral valve was most frequently involved (10/16 cases) with 4 of the patients having concomitant aortic valve involvement. The overall mortality rate was 44.4%. Antibiotic therapy of enterobacter endocarditis should consist of the combination of a beta-lactam antibiotic and an aminoglycoside with careful monitoring of blood cultures to assure the adequacy of therapy. Resistance of enterobacter to previously susceptible antibiotics may occur during therapy due to induction of a chromosomally-mediated beta-lactamase, necessitating a change in antimicrobial therapy. Valvular surgery is indicated for patients failing medical management.

Endocarditis, Bacterial↗

PubMed1999

Emergence of multidrug-resistant Enterobacter cloacae: nosocomial outbreak or change of microbial ecology?

Frequent selection of mutants resistant to extended and broad spectrum cephalosporins in Enterobacter cloacae is observed in hospital. As we noticed an unusual number of isolates of these strains and to answer the question arose whether these Enterobacter had a common source, we retrospectivally studied 56 strains collected in 11 wards of the hospital. Using PFGE with Spe 1 restriction analysis we identified a prevalent clone (11 patients) dispatched in 8 wards. We also obviously proved cross-contamination patients to patients with other clones. PFGE allow us to point out that clonal Enterobacter cloacae has taken place in our hospital, even if there is no real outbreak. A reinforcement of basic hygienic measures and a control of antibiotics prescription seemed very important to jugulate the sudden increase of multiresistant Enterobacter cloacae prevalence.

Cephalosporin Resistance↗

PubMed2000

[Nosocomial enterobacter - sepsis in neonatal intensive care unit in Pleven].

At the recent years considerably increased the role of Enterobacter spp as causes of nosocomial sepsis in different intensive units. It is determined of their possibilities to change quick antibiotic resistance especially to third generation cephalosporins and wide insemination of the environment. During the period from 29.10.1997 to 30.12.1997 in Neonatal intensive care unit--Pleven have been registered 9 cases of nosocomial sepsis caused by Enterobacter aerogenes. The clinic picture run with shock, temperature instability, hyperbilirubinemia, mottling respiratory insufficiency, I/T ratio > 0.2. Thrombocytopenia. Detection of the pathogen organisms present wide antibiotics resistance to cephalosporins. The microbiological control of the environment have been isolated Enterobacter spp from neonatal intensive unit, delivery room, unit for healthy newborn. The persistence of Enterobacter infections is a result of low supply of household linen, detergents, single-used products and widely used of cephalosporins, insufficient staff and overpopulation with patients.

Bulgaria↗

PubMed2001

[The inducibility of Amp C enzyme of Enterobacter cloacae and its susceptibility to enzyme inhibitor].

OBJECTIVE: To study the inducibility of Amp C enzyme of Enterobacrter cloacae and its susceptibility to enzyme inhibitor. METHODS: The in vitro activities of the fourth generation cephalosporins-cefepime, the third generation cephalosporins-cefuroxime, cefotaxime, ceftazidime combined with beta-lactamase inhibitor sulbactam against 10 strains of ceftazidime resistant Enterobacter cloacae selected from the hospitals was studied with agar two fold dilution method. The inducibility of beta-lactam antibiotics in common use clinically to Amp C enzyme and the inhibitory action of 3 inhibitors to Amp C enzyme were studied with ultraviolet spectrophotometry and RTPCR. RESULTS: Sulbactam can not enhance the activity of ceftazidime against Enterobacter cloacae. Cefepime has a strong activity against ceftazidime resistant Enterobacter cloacae. Imipenem has a strong inductive action to Amp C enzyme. Ro481220 has a strong inhibitory action to Amp C enzyme. CONCLUSION: Infections caused by Enterobacter cloacae producing Amp C enzyme can be treated by cefepime.

Bacterial Proteins↗

PubMed1992

Cefoxitin-induced antibiotic resistance in Enterobacter species in the community hospital.

The aim of this study was to determine whether beta-lactamases could be induced by cefoxitin in the community hospital, since this problem of antibiotic resistance has been shown to exist at the tertiary care level. One hundred sixty-six Enterobacter species isolated from patients in two community hospitals in Dayton, Ohio, were tested for cefoxitin induction of beta-lactamase production by a disk-approximation method. Piperacillin and cefoxitin disks were placed in approximation to each other on Mueller-Hinton plates inoculated with Enterobacter species with appropriate controls. Three Enterobacter strains (1.8%) showed truncation of the zone of inhibition (indicating beta-lactamase induction) with sensitivity to both cefoxitin and piperacillin. However, 84 strains (50.6%) showed truncation around the piperacillin disk with resistance to cefoxitin. One hundred fifty (90.0%) strains showed resistance to cefoxitin. These data indicate that cefoxitin induction of beta-lactamases in Enterobacter species is indeed a potential problem in incurring antibiotic resistance in the community hospital.

Cefoxitin↗

PubMedDate not supplied

[Profiles of the utilization of 20 amino acids as the only source of nitrogen and carbon in bacteria of the genera Klebsiella, Enterobacter, Serratia, Escherichia].

The profiles of the utilization of 20 protein amino acids in 118 Klebsiella pneumoniae sub- sp. pneumoniae, K. oxytoca, K. planticola, K. mobilis, Enterobacter cloacae, Serratia marscescens, S. liquefaciens, Escherichia coli strains isolated from clinical material were studied. The utilization of amino acids was determined on minimal saline agar containing amino acid as the only source of nitrogen and carbon; the results were evaluated after 72-hour incubation at 37 degrees C. 17 profiles of amino-acid utilization were thus determined, most of them genus-specific in enterobacteria: Klebsiella (profiles No. 1--6, 9, 10), Enterobacter (No. 11--13), Serratia (No. 14--16), Escherichia (No. 17). The full coincidence of amino-acid utilization profiles in bacteria of K. mobilis (No. 1, 6) and K. pneumoniae subsp. pneumoniae with out of such profiles in bacteria of the genera Enterobacter, Serratia, Escherichia was established, which confirmed that K. mobilis (formerly Enterobacter aerogenes) belonged to the genus Klebsiella.

Amino Acids↗

PubMed1986

Phage types, antibiograms and R-plasmids of Klebsiella and Enterobacter isolated from hospital environment and food.

Four-hundred and twenty-two Klebsiella strains and 294 Enterobacter strains were isolated from direct or indirect environment of hospitalized patients, from foodstuffs, foods, culinary utensils and staff in hospital and in catering establishments. Of Klebsiella, the species K. aerogenes (76.5%) of Enterobacter, the species E. cloacae (77.6%) occurred the most frequently in all specimens. Klebsiella strains were typable in 68.5%; 53.1% of the Enterobacter strains were sensitive to phage. Most of the untypable Klebsiella and Enterobacter strains and the multiresistant strains originated from screening in hospitals. Sensitive bacteria as well as those resistant to one or two antibiotics may be potentially dangerous for the patient consuming them, since they may become multiresistant due to R-plasmid transfer.

Anti-Bacterial Agents↗

PubMed1978

Neonatal meningitis due to Enterobacter cloacae.

Enterobacter species, in recent years, have been divided into E aerogenes, E hafniae, E liquefaciens, and E cloacae. Early reviews of neonatal meningitis include some cases due to Klebsiella-Aerobacter,(1) and recent reviews(2,3) include Enterobacter which did not divide them into species of Enterobacter. Reported here is a case of neonatal meningitis due to a gram-negative organism, Enterobacter cloacae.

Enterobacter↗

PubMed2004

The growth profile, thermotolerance and biofilm formation of Enterobacter sakazakii grown in infant formula milk.

AIMS: To study the growth, thermotolerance and biofilm formation of the emergent pathogen Enterobacter sakazakii in infant formula milk (IFM). METHODS AND RESULTS: The temperature range, death kinetics and biofilm formation of E. sakazakii were determined using impedance microbiology and conventional methods. In IFM the organism grew as low as 6 degrees C and optimally at 37-43 degrees C. In faecal coliform tests, 23% of strains (n = 70) produced gas from lauryl sulphate broth (LSB) at 44 degrees C after 48 h incubation. Three strains failed to grow in LSB at any of the temperatures. The D-value of cells suspended in IFM was determined between 54 and 62 degrees C. The resultant z-value was 5.7 degrees C. The organism was able to adhere and grow on latex, polycarbonate, silicon and to a lesser extent stainless steel. CONCLUSIONS: Enterobacter sakazakii was able to grow at refrigeration temperatures and on infant-feeding equipment. The thermotolerance of the organism was similar to other Enterobacteriaceae and should be killed during standard pasteurization treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterobacter sakazakii has been associated with infant meningitis through consumption of contaminated IFM. Enterobacter sakazakii is able to grow in IFM during storage at refrigeration temperatures and attach to infant-feeding equipment, which may become reservoirs of infection.

Animals↗

PubMed2006

Cloning and characterization of Enterobacter sakazakii pigment genes and in situ spectroscopic analysis of the pigment.

Enterobacter sakazakii is considered an opportunistic foodborne pathogen that is characterized by formation of yellow-pigmented colonies. Because of the lack of basic knowledge about Enterobacter sakazakii genetics, the BAC approach and the heterologous expression of the pigment in Escherichia coli were used to elucidate the molecular structure of the genes responsible for pigment production in Enterobacter sakazakii strain ES5. Sequencing and annotation of a 33.025 bp fragment revealed seven ORFs that could be assigned to the carotenoid biosynthesis pathway. The gene cluster had the organization crtE-idi-XYIBZ, with the crtE-idi-XYIB genes putatively transcribed as an operon and the crtZ gene transcribed in the opposite orientation. The carotenogenic nature of the pigment of Enterobacter sakazakii wt was ascertained by in situ analysis using visible microspectroscopy and resonance Raman microspectroscopy.

Carotenoids↗

PubMed1991

Enterobacter bacteremia in the community hospital.

BACKGROUND: The purpose of this study was to examine the epidemiological and clinical characteristics of Enterobacter bacteremia in the community hospital, where nosocomial infections are not commonly studied. METHODS: The blood culture records of five community hospitals in the Dayton, Ohio, area were reviewed to find cases of Enterobacter bacteremia. The respective hospital charts were then reviewed. RESULTS: Seventy-five episodes of Enterobacter bacteremia were reviewed. Eighty percent (60) of the organisms were nosocomially acquired, and 20% (15) were community acquired. The median age of the patients was 64 years. In 39% (29) of the episodes, fever was not the primary manifestation. The mortality rate was 29% (22). In 30% of the cases, the portal of entry for the bacteremia was unknown. The most common known portals of entry were genitourinary, gastrointestinal or biliary, and peritoneal. The most common underlying disorders were malignancy, postoperative states, and diabetes mellitus. In 9% of the cases, no underlying disorder was detected. The organisms showed high sensitivity to chloramphenicol, aminoglycosides, piperacillin sodium, and cefotaxime sodium. High degrees of resistance were shown to ampicillin, first-generation cephalosporins, and cefoxitin. Eighty-four percent (46) of the patients treated appropriately survived, and 55% (11) of the patients treated inappropriately died. CONCLUSIONS: Enterobacter bacteremia is most commonly nosocomially acquired and appears to be a problem in the community hospital. Appropriate therapy improves rates of patient survival.

Adolescent↗

PubMed1985

Enterobacter bacteremia. An analysis of 50 episodes.

During a six-year period, 147 patients had Enterobacter bacteremia (3.8% of the episodes of bacteremia), with an incidence of 1.25 per 1,000 admitted patients. We chose a random group of 50 cases for analysis. The disease was community acquired in 24% of the cases and nosocomially acquired in the remaining 76%. The bacteremia was unimicrobial in 70% and part of a polymicrobial bacteremia in 30%. The species most commonly causing bacteremia was Enterobacter cloacae. Portals of entry, in decreasing order of frequency, were unknown, surgical wound, respiratory tract, and urinary tract. The most common clinical finding was fever (92%). Shock occurred in 30% of the patients, and only two patients had evidence of disseminated intravascular coagulation. Of the Enterobacter isolates, 12% were resistant to gentamicin. Overall mortality was 42%; factors associated with a poor prognosis were inadequacy of antimicrobial chemotherapy, septic shock, type of underlying disease, clinical condition, and requirement of intensive care.

Adolescent↗

PubMed1988

Distribution and antibiotic susceptibility of extraintestinal clinical isolates of Klebsiella, Enterobacter and Serratia species.

A total of 451 extraintestinal, clinically relevant strains of the Klebsiella, Enterobacter and Serratia spp. isolated over a nine-month period from hospitalized patients at four different centers in Italy were investigated. Identification using the API 20E system showed that isolates belonged to 12 different species. Overall, strains of Klebsiella, Enterobacter and Serratia were in a ratio of approximately 3.4:2:1. Fifty-nine per cent of all strains were from urinary specimens, 12% from respiratory secretions, 10% from wounds and abscesses, and lower percentages from other sources. All strains were tested for their susceptibility to ten antibiotics. The rate of resistance to most drugs was generally greater in Enterobacter and Serratia than in Klebsiella. The overall incidence of strains of the intermediate category (i.e. between full sensitivity and resistance) was unexpectedly high. Both the relative frequency and the antibiotic susceptibility of strains of the various species varied from center to center; possible reasons for such differences are examined.

Drug Resistance, Microbial↗

PubMed1993

Imipenem resistance in Enterobacter.

Blood cultures obtained on two separate occasions from a 37-year-old male who received multiple antibiotics (including imipenem) for treatment of repeated episodes of intraabdominal abscesses and bacteremia yielded two isolates of Enterobacter with reduced susceptibility to imipenem, extended-spectrum cephalosporins, penicillins and aztreonam. Both isolates were unstable, giving rise to different colony types, each of which produced a single, non-inducible Bush group 1 beta-lactamase (pI = 9.6) that hydrolyzed imipenem. Outer membrane proteins were analyzed but no differences were detected between strains with different levels of imipenem resistance. Three-dimensional tests performed in conjunction with disk diffusion susceptibility tests provided a rapid and convenient means of detecting the production of imipenem-hydrolyzing enzymes by the Enterobacter strains. These isolates provided additional evidence that overproduction of the group 1 cephalosporinase of Enterobacter can contribute to resistance to imipenem.

Adult↗

PubMed2006

Mutation in cyaA in Enterobacter cloacae decreases cucumber root colonization.

Strains of Enterobacter cloacae show promise as biological control agents for Pythium ultimum-induced damping-off on cucumber and other crops. Enterobacter cloacae M59 is a mini-Tn5 Km transposon mutant of strain 501R3. Populations of M59 were significantly lower on cucumber roots and decreased much more rapidly than those of strain 501R3 with increasing distance from the soil line. Strain M59 was decreased or deficient in growth and chemotaxis on most individual compounds detected in cucumber root exudate and on a synthetic cucumber root exudate medium. Strain M59 was also slightly less acid resistant than strain 501R3. Molecular characterization of strain M59 demonstrated that mini-Tn5 Km was inserted in cyaA, which encodes adenylate cyclase. Adenylate cyclase catalyzes the formation of cAMP and cAMP levels in cell lysates from strain M59 were approximately 2% those of strain 501R3. Addition of exogenous, nonphysiological concentrations of cAMP to strain M59 restored growth (1 mM) and chemotaxis (5 mM) on synthetic cucumber root exudate and increased cucumber seedling colonization (5 mM) by this strain without serving as a source of reduced carbon, nitrogen, or phosphorous. These results demonstrate a role for cyaA in colonization of cucumber roots by Enterobacter cloacae.

Adenylate Cyclase Toxin↗

PubMed2000

Enterobacter cowaniisp. nov., a new species of the family Enterobacteriaceae.

The name Enterobacter cowanii sp. nov. is proposed for a group of organisms referred to as NIH Group 42. Members of this species are Gram-negative, motile rods conforming to the definition of the family Enterobacteriaceae. The DNA relatedness of nine strains of NIH Group 42 to the proposed type strain of this species averaged 85% at 70 degrees C, whereas the relatedness to other species within the family Enterobacteriaceae was less than 38%. Because the DNA relatedness (5-38%) is closer to species of the genus Enterobacter than to other species of the family, the members of NIH Group 42 were placed in the genus Enterobacter. The majority of strains of E. cowanii were isolated from clinical specimens. A culture of the type strain (888-76) has been deposited in the Japan Collection of Microorganisms as JCM 10956.

Bacterial Typing Techniques↗

PubMed1994

Involvement of L-tryptophan aminotransferase in indole-3-acetic acid biosynthesis in Enterobacter cloacae.

L-Tryptophan aminotransferase (L-tryptophan:2-oxoglutarate aminotransferase; EC 2.6.1.27) from Enterobacter cloacae was purified 62-fold and characterized to determine its role in indole-3-acetic acid biosynthesis. The enzyme reversibly catalyzed the transamination of L-tryptophan with 2-oxoglutarate as the amino acceptor to yield indole-3-pyruvic acid and L-glutamate, and the Km values for L-tryptophan and indole-3-pyruvic acid were 3.3 mM and 24 microM, respectively. In the indole-3-acetaldehyde synthesis experiments in vitro, 94% of L-tryptophan was efficiently converted to indole-3-acetaldehyde by the purified L-tryptophan aminotransferase plus indolepyruvate decarboxylase. Furthermore, the amounts of L-tryptophan decreased with increases in the indolepyruvate decarboxylase activity, while the amounts of indole-3-acetaldehyde increased with increases in this activity. In genetic experiments, the amounts of L-tryptophan produced by Enterobacter and Pseudomonas strains harboring the gene for indolepyruvate decarboxylase were lower than those produced by these same strains without the gene, while the amounts of indole-3-acetic acid produced by Enterobacter and Pseudomonas strains harboring the gene for indolepyruvate decarboxylase were higher than those produced by these same strains without the gene. These results clearly show that L-tryptophan aminotransferase is involved in the indole-3-acetic acid biosynthesis and that indolepyruvate decarboxylase is the rate-limiting step in this pathway.

Carboxy-Lyases↗