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PubMed1994

Experience with Enterobacter bacteraemia in a Dublin teaching hospital.

In a review of Enterobacter bacteraemia in a 600-bedded teaching hospital, 22 episodes were identified in 20 patients over a 2-year period. An evaluation of risk factors suggested an association between Enterobacter infection and the presence of central venous catheters or use of H-2 receptor antagonists. These factors together with previous exposure of the patient to gentamicin, and prolonged stay in the intensive care unit, increased the likelihood of gentamicin-resistant Enterobacter bacteraemia. This finding has implications for the choice of antibiotic regimen in the empirical treatment of suspected Gram-negative septicaemia.

Bacteremia↗
PubMed2005

Nosocomial urosepsis caused by Enterobacter kobei with aberrant phenotype.

Enterobacter kobei is the species of the Enterobacter cloacae complex, which is phenotypically most closely related to the species E. cloacae. This is the first report of infection caused by a new biotype of E. kobei. A patient with a history of urinary bladder operation developed a urosepsis with an Enterobacter isolate displaying the E. cloacae phenotype. The isolate was classified to the species E. kobei by sequence analysis of the 16S-rDNA, 4 protein-coding genes and enterobacterial repetitive intergenic consensus (ERIC)-cluster analysis. E. kobei was originally described to be Voges-Proskauer (VP) negative. However, the isolates of the present case were VP-positive. After analyzing 120 biochemical tests included in the API20E and the Biotype 100 systems, 4 biochemical tests were identified potentially differentiating this new biotype from E. cloacae.

Cross Infection↗
PubMed2003

Correlation between bacterial haemoglobin gene (vgb) and aeration: their effect on the growth and alpha-amylase activity in transformed Enterobacter aerogenes.

AIMS: To evaluate the effects of bacterial haemoglobin on bacterial growth and alpha-amylase formation under different aeration conditions. METHODS AND RESULTS: Enterobacter aerogenes was transformed with the gene encoding Vitreoscilla (bacterial) haemoglobin, vgb. The growth kinetics and ability to synthesize alpha-amylase enzyme were investigated in this transformed Enterobacter strain as well as in two other Enterobacter control strains that do not harbour the vgb gene. Such comparison was made under variable aeration conditions, using the agitation rate as a measure of aeration. The expression of bacterial haemoglobin-supported cell growth determined as O.D.600 and cell viability in addition to the alpha-amylase production. These positive effects of bacterial haemoglobin were observed under both low and high aerations, but at different extents. CONCLUSIONS: In addition to improving cell growth under low aeration, the bacterial haemoglobin is able to promote bacterial cell tolerance during exposure to high oxygen tension. SIGNIFICANCE AND IMPACT OF THE STUDY: The expression of bacterial haemoglobin is advantageous in reducing the burden of certain toxic conditions such as high oxygen levels. It may have the same impact on some environmental toxic substances. This, haemoglobin biotechnology can be extended to induce enzymes of pollutants degradation or production of some useful industrial substances.

Bacterial Proteins↗
PubMed1999

Enterobacter aerogenes outbreak in a neonatal intensive care unit.

BACKGROUND: Enterobacter aerogenes, a Gram-negative bacterium, is an important, although infrequent, cause of nosocomial bacteremia in the hospitalized pediatric and neonatal population. Enterobacter aerogenes was isolated for the first time in our neonatal intensive care unit (NICU) from blood culture of a 5-day-old neonate; 12 more cases were discovered in the next 70 days. The present report summarizes the clinico-bacteriological spectrum and outcome of the affected neonates. Efforts made to find the source of infection and curb the outbreak are also presented. METHODS AND RESULTS: Thirteen newborns, including seven preterms, acquired E. aerogenes septicemia. Perinatal risk factors were present in all the neonates. The mean birthweight of affected infants was 1880 +/- 540 g. Symptoms appeared at a mean age of 3.5 +/- 1.5 days (range 3-8 days). The clinical presentation was indistinguishable from septicemia caused by other Gram-negative organisms. Complications encountered included sclerema, bleeding diathesis, meningitis and shock. The organism, isolated from blood in all and from the cerebrospinal fluid in two cases, was found to be resistant to all antibiotics in the first five cases, but turned sensitive to gentamicin, cefotaxime and amikacin during the latter half of the epidemic. The bacterium in the last case (no. 13) was again found to be resistant to all the antibiotics. Overall mortality was 46.2%; the mean interval between onset of symptoms and death being 2.3 +/- 1.8 days. The organism was traced to the rubber pipe attached to a foot-operated suction machine in the NICU. The neonatal unit was temporarily closed, fumigated and reopened with strict instructions to follow proper hand washing protocol and ensure cohort nursing of infected infants. CONCLUSIONS: Enterobacter aerogenes is capable of causing nosocomial outbreaks of septicemia in NICU. Low birthweight infants with associated perinatal risk factors appear to be predisposed. The sensitivity patterns of the isolates highlight the capability of E. aerogenes to acquire or lose resistance to antibiotics rapidly during treatment. A high mortality rate coupled with a short interval between onset of symptoms and death, suggested high virulence of the strain.

Cross Infection↗
PubMed2004

Isolation of endophytic diazotroph Pantoea agglomerans and nondiazotroph Enterobacter asburiae from sweetpotato stem in Japan.

AIMS: To isolate and identify diazotrophic endophytes in the stem of Japanese sweetpotato cv. Koganesengan. METHODS AND RESULTS: Surface-sterilized and thinly sliced (1-2 mm) sweetpotato stem samples were incubated in test tubes with semi-solid modified Rennie (MR) medium. The test tubes were assayed for acetylene reduction activity (ARA) 5 days after incubation at 30 degrees C. Twelve isolates were obtained from MR plates inoculated with a loop of semi-solid MR medium from ARA+ tubes. However, ARA test showed that only nine isolates were diazotrophic and three were nondiazotrophic strains. Using the API 20E diagnostic kit, four diazotrophic isolates were identified as strains of Pantoea spp. and five isolates as Klebsiella spp. The nondiazotrophic bacteria were strains of Enterobacter spp. A diazotrophic isolate Pantoea sp. MY1 and nondiazotrophic isolate Enterobacter sp. MY2 were identified to the species level by full sequence analysis of 16S rRNA gene. The results showed that MY1 had 99.2% similarity to Pantoea agglomerans ATCC 27155 and MY2 had 99.5% similarity to Enterobacter asburiae ATCC 35953. CONCLUSION: The stem of sweetpotato cv. Koganesengan was colonized by diazotrophic endophyte P. agglomerans and nondiazotrophic endophyte E. asburiae. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is an essential step toward understanding the ecology and interaction between endophytic bacteria and sweetpotato.

Bacterial Typing Techniques↗
PubMedDate not supplied

[Multiple cerebral infarcts with resulting multicystic encephalomalacia in a premature infant with Enterobacter sakazakii meningitis].

Enterobacter sakazakii is an uncommon cause of neonatal meningitis. The prognosis of newborns with meningitis due to Enterobacter sakazakii is poor, the fatality rate is reported as high as 50%. Survivors usually have severe neurologic complications. Most computed tomography (CT) findings were low density lesions of white matter and cortex suggesting infarctions which underwent cystic degeneration. We present one premature baby with meningitis due to Enterobacter sakazakii and large bilateral regions of hypo- and hyperdensity suggesting massive hemorrhagic and nonhemorrhagic intracerebral infarctions leading to multiple cystic encephalomalacia.

Cerebral Infarction↗
PubMed2003

Outbreak of TEM-24-producing Enterobacter aerogenes in a Spanish hospital.

Organisms encoding multidrug resistance genes are becoming increasingly prevalent. During a 2-month period (December, 2000, to January, 2001), 83 consecutive isolates of Enterobacter spp. were collected in our microbiology department. Antibiotic susceptibility was determined using the Vitek II automatic system. We selected strains with decreased susceptibility to extended-spectrum cephalosporins. The double-disk potentiation test was positive in 10 of these strains, indicating the presence of extended-spectrum beta-lactamases (ESBLs). Polymerase chain reaction (PCR), isoelectric focusing (IEF), and sequencing identified TEM 24 beta-lactamase in the 10 selected E. aerogenes. Random amplification of polymorphic DNA (RAPD-PCR) revealed the same clonal origin for all the strains tested and strongly suggest an outbreak of multidrug-resistant E. aerogenes. To follow up the trends in ESBLs-producing Enterobacter infections in the hospital over time, we repeated the study 1 year later (December, 2001, to February, 2002). Only three ESBLs-producing Enterobacter were found. All of them corresponded to the previously characterized clone.

Adult↗
PubMed1993

Antibiotic therapy for enterobacter meningitis: a retrospective review of 13 episodes and review of the literature.

Enterobacter meningitis is an uncommon form of meningitis whose treatment poses a therapeutic dilemma because of the development of resistance to the third-generation cephalosporins while the patient receives therapy. In recent years, we have been using trimethoprim-sulfamethoxazole (TMP-SMZ) as treatment for this infection. In this report, we reviewed 13 episodes of enterobacter meningitis that were treated with various antibiotic regimens and 33 episodes from the literature. We found that the development of resistance to beta-lactam agents may be much higher than that seen in bacteremias (approximately 30%), that the case-fatality rate is lower among our patients than among those described previously, and that all patients who received TMP-SMZ were cured, compared with about 70% of those receiving beta-lactam agents. TMP-SMZ appears to be an acceptable alternative to the cephalosporins for the treatment of enterobacter meningitis.

4-Quinolones↗
PubMedDate not supplied

Bacteremia caused by Enterobacter: 15 years of experience in a cancer hospital.

A total of 296 episodes of bacteremia due to Enterobacter occurred in 281 patients with cancer between 1972 and 1986. The majority of these episodes were caused by Enterobacter cloacae. Seventy-four percent of the patients developed their infection while in the hospital and 55% had received therapeutic antibiotics during the 10 days preceding the onset of the infection. Enterobacter bacteremia was associated with shock in 24% of the patients and with disseminated intravascular coagulation in only 3%. The overall rate of response to therapy was 79% and increased to 85% during the last 5-year period. Only five patients remained afebrile during their infection, but four of these five died. Only 37% of the patients with shock responded to therapy compared with 93% of the patients without shock. The rate of response to therapy was 86% among patients without pulmonary infection compared with only 53% among those with pulmonary infection. The response rate to therapy with a single antibiotic was 73% and that to therapy with two antibiotics was 85%. As single therapeutic agents aminoglycosides were less effective than beta-lactam agents.

Adolescent↗
PubMed1993

Emergence of resistance to imipenem in Enterobacter isolates masquerading as Klebsiella pneumoniae during therapy with imipenem/cilastatin.

Clinical isolates identified as Klebsiella pneumoniae by the Vitek, Enterotube II, and API 20E systems were recovered from a patient undergoing therapy with imipenem/cilastatin. These isolates were resistant to multiple beta-lactam agents, and some were even resistant to imipenem. Analysis revealed a Bush group 1 beta-lactamase, and imipenem resistance corresponded to the loss of outer-membrane proteins in strains expressing high levels of this beta-lactamase. Further characterization efforts yielded abnormal but positive results of tests for ornithine decarboxylase production and motility, and chromosomal homology to an Enterobacter cloacae ampR, ampC probe was detected. These results suggested that the organisms were actually of an Enterobacter species, perhaps Enterobacter aerogenes. Cefoxitin resistance may be a useful marker for preventing this misidentification in the future; misidentification of such organisms poses a hazard, as it may lead to inappropriate beta-lactam therapy for infections caused by organisms that have the potential for resistance due to inducible group 1 cephalosporinases.

Aged↗
PubMed2001

Enterobacter sakazakii infections among neonates, infants, children, and adults. Case reports and a review of the literature.

Enterobacter sakazakii can cause serious infections especially among the very young and the elderly. It continues to be more common among neonates and infants than adults. Its tropism for the central nervous system in neonates and infants remains a mystery. Among neonates and infants, E. sakazakii has a propensity to cause meningitis resulting in ventriculitis, brain abscess or cyst formation, and development of hydrocephalus requiring ventricular-peritoneal shunt. Computed tomography of the head is therefore useful in following patients with E. sakazakii meningitis. Mortality and morbidity of E. sakazakii meningitis is high, and virtually all patients recovering from the central nervous system infection suffered mental and physical developmental delays. The case-fatality rate decreased among patients with meningitis treated with the third-generation cephalosporins. Most adults with E. sakazakii infection had serious underlying diseases and 50% of the adults with the infection had malignancies. However there has never been a known case of meningitis. Increasing antibiotic resistance among Enterobacter species should lead one to consider using the carbapenems or the newer cephalosporins in combination with a second agent such as an aminoglycoside. Limited data suggest that trimethoprim-sulfamethoxazole may be a useful agent in the treatment of infections caused by the Enterobacter species, especially in view of the production of extended-spectrum beta-lactamases capable of inactivating the cephalosporins and extended-spectrum penicillin.

Adult↗
PubMed1987

Enterobacter pneumonia.

Enterobacter species have not been well recognized as important lower respiratory tract pathogens. We describe 11 cases of Enterobacter pneumonia, seven diagnosed by transtracheal aspiration and four by simultaneous blood and sputum cultures. The infections were usually nosocomial, and were fatal in five patients. Our patients were old (mean age 65 +/- 12.3 years) with chronic obstructive pulmonary disease (COPD) as a common underlying disease. Enterobacter species are important pathogens causing nosocomial pneumonias, especially in elderly patients with COPD.

Adult↗
PubMed1985

Fimbrial and non-fimbrial haemagglutinins in Enterobacter aerogenes.

Ten strains of Enterobacter aerogenes were examined for their ability to produce haemagglutinins and fimbriae. Nine strains formed a mannose-sensitive (MS) haemagglutinin associated with thin (4 nm) non-channelled fimbriae. These thin fimbriae of E. aerogenes were antigenically different from the thin fimbriae of other fimbriate strains of Enterobacter and Klebsiella and probably represent a new kind of fimbria not previously described in Enterobacteriaceae. Eight of these same nine strains also formed a non-fimbrial mannose-resistant, proteus-like (MR/P) haemagglutinin. The formation of thin fimbriae associated with MS haemagglutinin and of non-fimbrial MR/P haemagglutinin are properties not associated with other strains of Enterobacter and Klebsiella. E. aerogenes strain NCIB11460 was unusual among the strains examined in this series in that it alone produced mannose-resistant, Klebsiella-like (MR/K) haemagglutinin and type-3 fimbriae which, as judged by immunoelectronmicroscopy, were antigenically like those of type-3 fimbriate Klebsiella strains. The identifying characters of this exceptional strain of E. aerogenes are discussed in detail. All ten strains also produced thick fimbriae which by immunoelectronmicroscopy behaved like the type-1 fimbriae of Klebsiella strains. However, correlation between their presence and the production of MS haemagglutinin in E. aerogenes was not established. The findings are discussed in the light of the present difficult taxonomic status of E. aerogenes within the tribe Klebsielleae.

Enterobacter↗
PubMed1977

Enzymatic and immunological characterization of a new cephalosporinase from Enterobacter aerogenes.

A hospital strain of Enterobacter aerogenes (MULB 250) isolated from a urinary tract infection was found to be cephalosporin and ampicillin resistant and carbenicillin susceptible. The beta-lactamase produced by this strain was extracted and purified by means of affinity chromatography, using a cephalosporin C-bound Sepharose 4B column. The purified enzyme was tested for hydrolysis of penicillin and various cephalosporins. The K(m) value is 11.8 muM for benzyl penicillin and 130 muM for cephalosporin C. The isoelectric point of the enzyme is 9.3, and its molecular weight is 29,500 +/- 1,000. Rabbit antiserum obtained against this MULB 250 beta-lactamase showed no cross-reaction with other penicillinases or cephalosporinases in neutralization tests. Comparisons of results obtained with other beta-lactamases, particularly from Enterobacter cloacae P99, indicate that the Enterobacter MULB 250 enzyme presents a typical cephalosporinase profile. As far as we know, this type of enzyme is relatively rare.

Amidohydrolases↗
PubMed1983

Influence of clindamycin on derepression of beta-lactamases in Enterobacter spp. and Pseudomonas aeruginosa.

Previous studies in this and other laboratories have shown that derepression of beta-lactamases in strains of Enterobacter and Pseudomonas spp. is responsible for the rapid development of resistance to a variety of beta-lactam antibiotics. The purpose of the current study was to evaluate the effects of clindamycin on derepression of beta-lactamases in these two genera. In tests with four strains of each genus, clindamycin diminished derepression in one isolate of each genus and completely prevented derepression in a second Enterobacter isolate (strain 55). Additional tests with strain 55 revealed that other inhibitors of macromolecular synthesis did not completely prevent derepression of beta-lactamase when tested at concentrations that did not inhibit replication. However, clindamycin did not affect synthesis of beta-lactamase that was constitutively produced in a mutant of this strain (55M). It also did not inhibit derepression of beta-galactosidase in either strain 55 or 55M. Clindamycin did not diminish the bactericidal effects of beta-lactam antibiotics against Enterobacter or Pseudomonas spp. However, it enhanced the bactericidal activity of cefamandole against strain 55. These in vitro effects of clindamycin on strain 55 that were related to prevention of derepression of beta-lactamase were confirmed in vivo with an animal model of infection. These results indicate that in some strains, clindamycin can specifically prevent derepression of beta-lactamases without inhibiting growth. Such a selective effect may provide a new approach for the enhancement of the antibacterial activity of certain beta-lactam antibiotics.

Cefamandole↗
PubMed2005

Extended-spectrum beta-lactamases among Enterobacter isolates obtained in Tel Aviv, Israel.

The extended-spectrum beta-lactamase (ESBL)-producing phenotype is frequent among Enterobacter isolates at the Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. We examined the clonal relatedness and characterized the ESBLs of a collection of these strains. Clonal relatedness was determined by pulsed-field gel electrophoresis. Isoelectric focusing (IEF) and transconjugation experiments were performed. ESBL gene families were screened by colony hybridization and PCR for bla(TEM), bla(SHV), bla(CTX-M), bla(IBC), bla(PER), bla(OXA), bla(VEB), and bla(SFO); and the PCR products were sequenced. The 17 Enterobacter isolates studied comprised 15 distinct genotypes. All isolates showed at least one IEF band (range, one to five bands) whose appearance was suppressed by addition of clavulanate; pIs ranged from 5.4 to > or = 8.2. Colony hybridization identified at least one family of beta-lactamase genes in 11 isolates: 10 harbored bla(TEM) and 9 harbored bla(SHV). PCR screening and sequence analysis of the PCR products for bla(TEM), bla(SHV), and bla(CTX-M) identified TEM-1 in 11 isolates, SHV-12 in 7 isolates, SHV-1 in 1 isolate, a CTX-M-2-like gene in 2 isolates, and CTX-M-26 in 1 isolate. In transconjugation experiments with four isolates harboring bla(TEM-1) and bla(SHV-12), both genes were simultaneously transferred to the recipient strain Escherichia coli HB101. Plasmid mapping, PCR, and Southern analysis with TEM- and SHV-specific probes demonstrated that a single transferred plasmid carried both the TEM-1 and the SHV-12 genes. The widespread presence of ESBLs among Enterobacter isolates in Tel Aviv is likely due not to clonal spread but, rather, to plasmid-mediated transfer, at times simultaneously, of genes encoding several types of enzymes. The dominant ESBL identified was SHV-12.

Anti-Bacterial Agents↗
PubMed1968

Differentiation of Klebsiella-Enterobacter (Aerobacter)-Serratia by biochemical tests and antibiotic susceptibility.

Studies were undertaken for the differentiation of members of the Klebsiella-Enterobacter (Aerobacter)-Serratia division by biochemical tests and antibiotic susceptibility. A total of 67 cultures were tested. Strain identification was readily accomplished with the use of motility tests and arabinose fermentation. In addition, a practical schema, based on sensitivity pattern, proved valuable in the classification of the different strains. Most (if not all) Klebsiella strains were susceptible to cephalothin, and all were sensitive to colistin. Enterobacter strains were resistant to cephalothin but susceptible to colistin. In contrast to those other members of the group, all Serratia strains were resistant to both cephalothin and colistin. The combination of a limited number of biochemical reactions and single-disc sensitivity tests appears to be a logical approach for the tentative identification of Klebsiella-Enterobacter (Aerobacter)-Serratia strains.

Bacteriological Techniques↗
PubMed1969

Klebsiella, Enterobacter, and Serratia: biochemical differentiation and susceptibility to ampicillin and three cephalosporin derivatives.

Three hundred twenty-nine strains of the tribe Klebsielleae were compared by several biochemical tests and by susceptibility to selected antibiotics. Biochemical tests included urease, amino acid decarboxylase, and hydrogen sulfide production; fermentation of lactose and dextrose; motility; and tests in the IMViC (indole, methyl red, Voges-Proskauer, citrate) series. The isolates were: Klebsiella species, 67.5%; Enterobacter species, 28%, and Serratia species, 4.5%. Minimal inhibitory concentrations of cephaloridine, cephalothin, and a new cephalosporin, cephalexin, and of ampicillin were determined by the agar dilution procedure. Cephalosporins at 20 mug/ml or less inhibited 90% of the Klebsiella strains but only 15% of the Enterobacter strains. Ampicillin inhibited 27% of Enterobacter strains and 17% of Klebsiella strains. Serratia isolates were insensitive to the cephalosporins and ampicillin. The results suggest that precise identification of this group to the generic level can be accomplished readily in the clinical laboratory and that such information is helpful in the preliminary selection of an antibiotic for treatment of clinical infections.

Ampicillin↗