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PubMed1991

Localization of cephalosporinase in Enterobacter cloacae by immunocytochemical examination.

Enterobacter cloacae NUH10 was isolated at Nagasaki University Hospital in 1987. E. cloacae NUH10 is a mutant strain which produces high levels of cephalosporinase. E. cloacae ATCC 23355 is known to be sensitive to so-called third generation cephems and produces an inducible cephalosporinase. The polyclonal antibody to cephalosporinase extracted from E. cloacae NUH10 was utilized in post-embedding immunogold labeling in order to localize this protein in E. cloacae ATCC 23355 and E. cloacae NUH10. Immunocytochemical localization of the cephalosporinase in both strains was observed with and without incubation with an inducer. Cephalosporinase was detected in both the cytoplasm and periplasmic space of E. cloacae ATCC 23355 and E. cloacae NUH10 incubated in medium including cefoxitin as an inducer. In the case of incubation without the inducer, a small quantity of cephalosporinase was located in the periplasmic space in either strain of bacteria. Western blot analysis showed that cephalosporinase was predominantly localized in the periplasmic space rather than in the cytoplasmic space.

Anti-Bacterial Agents↗
PubMed1995

Effects of tazobactam on the frequency of the emergence of resistant strains from Enterobacter cloacae, Citrobacter freundii, and Proteus vulgaris (beta-lactamase derepressed mutants).

When Enterobacter cloacae, Citrobacter freundii, and Proteus vulgaris were treated with piperacillin (PIPC) in combination with tazobactam (TAZ), the in vitro frequency of emergence of resistant strains (beta-lactamase producing mutants) was lower than with PIPC or ceftazidime (CAZ) treated bacteria. In a mouse intraperitoneal infection model caused by E. cloacae, beta-lactamase derepressed mutants were detected following therapy with PIPC or CAZ, although no derepressed mutants were detected after treatment with PIPC in combination with TAZ. This suppression of the selection of derepressed mutants, which produce large amounts of beta-lactamases, by the combination of TAZ and PIPC suggests that the combination delays the increase of resistant mutants compared with PIPC alone.

Animals↗
PubMed1981

An outbreak of pseudobacteremia caused by Enterobacter cloacae from a phlebotomist's vial of thrombin.

In a 15-day period, seven patients in a small hospital each had one blood culture positive for Enterobacter cloacae. None of the seven patients was septic. All seven positive culture specimens had been obtained by phlebotomist A, who also had obtained 13 negative culture specimens in the same period. Seven other phlebotomists had drawn 69 blood samples for culture during the same period; none had yielded any microorganism (p = 0.00001). Vials of thrombin, routinely used to coagulate blood specimens for chemical analysis, had been carried on the phlebotomy trays. We observed that phlebotomist A occasionally spilled drops of the viscous thrombin on her finger during the procedures. Culture of the thrombin on her tray yielded E. cloacae. No further cases of E. cloacae bacteremia occurred after she stopped drawing blood for culture and the thrombin on her tray was removed from use.

Blood Specimen Collection↗
PubMed1997

[The clinical manifestation and drug sensitive tests of lower respiratory tract infection by enterobacter cloacae. The Pulmonary Infection and Fibrosis Group, Thoracic Society Shanghai Medical Association].

OBJECTIVE: To study the clinical characteristics of lowar respiratory tract infection caused by E. cloacae and to investigate the drug sensitivities of E. cloacae strains. METHOD: (1) Analysing the clinical deta of 58 case with lowa respiratory tract infection of enterobacter cloacae defined by a putative standard, including ages, symptoms, signs, underlying diseases, sputum culture, X-ray findings and the prognosis. (2) Determining the drug sensitivities against the E. cloacae strains by K-B method. RESULTS: (1) There were 46 males and 12 females, with the mean age 56 +/- 19% cases diagnosed, who had underlying diseases, most were COPD. 41% cases were mixed infections with other bacteria, most of which were P. aeruginosa and K. pneumoniae. The chief symptoms were fever (72%) and productive cough (87%). The chest X-ray revealed inflammatory infiltration in lower lobes of both sides. The mortality rate was 9%. (2) The antimicrobial tests in vitro showed that these strains were multiresistant to antibiotics, but imipenem, amikacin, tobramycin, ciprofloxacin, cefoaperazone were sensitive. CONCLUSIONS: The lower respiratory tract infections caused by E. cloacae showed no specific clinical manifestations. However, the mortality was high. The diagnosis should be made according to bacteriologic examination combined with clinical and X-ray manifestations. Combining antibiotics therapy was recommanded according to antimicrobial sensitivity test.

Adult↗
PubMed1999

Rupture of the spleen associated with Enterobacter cloacae.

A 58-year-old male, with abdominal pain but no signs of sepsis, was admitted as a medical emergency. During hospitalization, spontaneous splenic rupture was diagnosed and splenectomy successfully performed. A smear revealed presence of Enterobacter cloacae on the splenic surface; histopathology demonstrated granulocytous infiltration of the spleen.

Enterobacter cloacae↗
PubMed2000

Enterobacterial repetitive intergenic consensus polymerase chain reaction typing of isolates of Enterobacter cloacae from an outbreak of infection in a neonatal intensive care unit.

BACKGROUND: Enterobacter cloacae has become a common cause of nosocomial infections. This study was designed to investigate the pattern of spread of E cloacae during an outbreak in a neonatal intensive care unit. METHODS: Enterobacterial repetitive intergenic consensus polymerase chain reaction was used to examine 111 E cloacae isolates from 17 patients, including 81 from surveillance cultures, 23 from endotracheal tubes, 3 from eyes, and 1 each from blood, urine, skin, and throat. Antibiotic susceptibility profiles were also obtained. RESULTS: Infection with E cloacae resulted from endogenous bacteria and from horizontal transmission. One group of 61 isolates, a third of which were obtained from clinical specimens, was uniformly susceptible to imipenem and ciprofloxacin only. A second group of 50 isolates, only 18% of which were obtained from clinical specimens, was susceptible to all antibiotics tested except for aminopenicillins and first-generation cephalosporins. CONCLUSION: These data indicate that (1) patient-to-patient spread is an important cause of E cloacae infection in the neonatal intensive care unit and (2) highly antibiotic-resistant E cloacae may emerge during an outbreak.

Academic Medical Centers↗
PubMed2000

Comparative aspects of the diffusion of norfloxacin, cefepime and spermine through the F porin channel of Enterobacter cloacae.

In Enterobacteriaceae, the permeability of the outer membrane to hydrophilic antibiotics is associated with the presence of pore-forming proteins. We tested the diffusion of the fluoroquinolone norfloxacin in four Enterobacter cloacae strains: a clinical isolate and three derivatives variously producing or lacking the D and F porins. We analysed the entry of norfloxacin into E. cloacae cells in the presence of either the polyamine spermine or the recently developed cefepime, which are known to penetrate through the Escherichia coli OmpF porin. Uptake of the fluoroquinolone was decreased in both cases; the initial rate of penetration decreased as more spermine blocked the channel. Our results indicate that, like beta-lactam molecules, fluoroquinolones translocate through the outer membrane via the F porin and that cefepime and norfloxacin entries are polyamine-sensitive. This suggests that the closure of the F porin channel by polyamines might modulate the susceptibility of E. cloacae to both fluoroquinolone and cephalosporin antibiotics.

Binding, Competitive↗
PubMed2000

[Susceptibility to antibiotics of some species of Enterobacter isolated from various clinical materials].

We investigated 185 strains of Enterobacter spp. (E. cloacae--143 strains, E. agglomerans--15 strains, E. sakazakii--14 strains and E. aerogenes--13 strains) isolated from several clinical materials. An agar diffusion assay on Mueller-Hinton Agar was performed (according to NCCLS procedure and National Reference Center of Microorganisms' Drug-sensitiveness at Central Laboratory of Sera and Vaccinations in Warsaw Poland). E. cloacae: about 90% of the strains were sensitive to carbapenems. 85.3% of the isolates were susceptible to piperacillin + tazobactam. About 80% of the strains were susceptible to cotrimoxazole and ciprofloxacin. E. agglomerans: all strains were susceptible to imipenem, and 86.7%--to meropenem. 86.7% of the strains were susceptible to ureidopenicillins + inhibitors of beta-lactamases. About 80% of the isolates were susceptible to cotrimoxazole and ciprofloxacin. E. sakazakii: all isolates were susceptible to carbapenems. About 90% of the strains were susceptible to cotrimoxazole and 50%--to ciprofloxacin. E. aerogenes: all of the strains were susceptible to carbapenems and ciprofloxacin, 92.3%--to cotrimoxazole.

Drug Resistance, Microbial↗
PubMed2000

[Comparative antibacterial activity of cefotaxime, ceftazidime and cefepime with regard to different strains of Enterobacter aerogenes selected for their resistance to third generation cephalosporins].

After being confronted with the isolation in our laboratory of numerous antibiotic-multiresistant Enterobacter aerogenes strains, we studied the in vitro antimicrobial activity of cefotaxime, ceftazidime, and cefepime alone or in association with sulbactam. For that, we selected 67 isolates according to their low level of susceptibility to cefotaxime. First, we deduced from a synergy test in presence of clavulanic acid and cloxacillin the production of an extended spectrum beta-lactamase (ESBL) and/or an overproduction of a chromosomal cephalosporinase. Three groups of strains were thus defined: one group of ESBL strains, another group of overproducing strains of chromosomal cephalosporinase, and a last group that produced the two types of enzymes. Minimal inhibitory concentrations (MICs) of each cephalosporin alone or in presence of 8 mg/L of sulbactam, gentamicin or amikacin were measured. Our results demonstrated the best activity of cefepime: MICs were low with a value inferior to 4 mg/L independently of the type of beta-lactamase. They were lower than 0.5 mg/L in presence of sulbactam against ESBL-producing strains. The cephalosporins could be used in association with aminoglycosides according to their susceptibility.

Cefepime↗
PubMed2000

Two-electron reduction of nitroaromatic compounds by Enterobacter cloacae NAD(P)H nitroreductase: description of quantitative structure-activity relationships.

Enterobacter cloacae NAD(P)H:nitroreductase catalyzes the reduction of a series of nitroaromatic compounds with steady-state bimolecular rate constants (kcat/Km) ranging from 10(4) M(-1) s(-1) to 10(7) M(-1) s(-1), and oxidizing 2 moles NADH per mole mononitrocompound. Oxidation of excess NADH by polynitrobenzenes including explosives 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenyl-N-methylnitramine (tetryl), has been observed as a slower secondary process, accompanied by O2 consumption. This type of 'redox cycling' was not related to reactions of nitroaromatic anion-radicals, but was caused by the autoxidation of relatively stable reaction products. The logs kcat/Km of all the compounds examined exhibited parabolic dependence on their enthalpies of single-electron- or two-electron (hydride) reduction, obtained by quantum mechanical calculations. This type of quantitative structure-activity relationships shows that the reactivity of nitroaromatics towards E. cloacae nitroreductase depends mainly on their hydride accepting properties, but not on their particular structure, and does not exclude the possibility of multistep hydride transfer.

Electrons↗
PubMed2002

Enterobacter sakazakii infections associated with the use of powdered infant formula--Tennessee, 2001.

Enterobacter sakazakii, a gram-negative, rod-shaped bacterium, is a rare cause of invasive infection with high death rates in neonates. This report summarizes the investigation of a fatal infection associated with E. sakazakii in a hospitalized neonate, which indicated that the infection was associated with the presence of the organism in commercial powdered formula fed to the infant. The implicated batch of formula has been recalled by the manufacturer. Clinicians should be aware of the potential risk for infection from use of nonsterile enteral formula in the neonatal health-care setting.

Enterobacter↗
PubMed2002

Superinfection of chronic multifocal osteomyelitis with Enterobacter cloacae.

A case is presented of a 6-year-old boy from Nigeria who developed chronic multifocal osteomyelitis with bilateral and symmetrical proximal humeral involvement. Superimposed changes of acute osteomyelitis were noted on the histopathological evaluation of the lesions. Cultures from both sides were positive for Enterobacter cloacae, which was presumably contracted during intravenous therapy for typhoid fever in Nigeria 1 month prior to his presentation.

Child↗
PubMed2003

Siderophore-mediated strategies of iron acquisition by extraintestinal isolates of Enterobacter spp.

A total of 89 examined Enterobacter isolates belonging to three species: E. cloaceae, E. aerogenes and E. sakazakii, produced iron chelators detected in universal CAS assay. In chemical assays the strains were shown to excrete mostly catecholate (88 strains) and hydroxamate (42 strains) type of siderophores. Forty-one strains produced both catecholate and hydroxamate siderophores whereas one isolate produced only hydroxamate. Besides, the isolates were screened for genes coding for another siderophore: yersiniabactin. The genes for biosynthesis and uptake of yersiniabactin are located on the high-pathogenicity island (HPI) of Yersinia spp. The presence of three marker genes irp1, irp2 and fyuA was estimated by polymerase chain reaction. Two strains: E. aerogenes and E. cloaceae possessed irp1, irp2 and fyuA genes. PCR products of irp1, irp2 and fyuA were of 240, 280 and 780 bp, respectively.

DNA, Bacterial↗
PubMed1992

Isolation of an Enterobacter agglomerans strain with inhibitory activity on Pseudomonas aeruginosa.

Antagonism between Enterobacter agglomerans and Pseudomonas aeruginosa was due to an extracellular substance produced by E. agglomerans which accumulates in the culture medium. This substance was also toxic to Escherichia coli and Staphylococcus albus and its MIC for P. aeruginosa ranged between 7.8 and 3.9 micrograms/ml. However, when the extracts from the culture medium were irradiated from 2 h with white light (15 mW/cm2), the MIC was lower (3.9-1.9 micrograms/ml) suggesting that the active substance was a phototoxin.

Antibiosis↗
PubMedDate not supplied

A medium for the presumptive detection of Enterobacter sakazakii in infant formula: interlaboratory study.

A standard method for the detection of Enterobacteriaceae was modified for the presumptive detection of Enterobacter sakazakii, and the modified method was validated in an interlaboratory trial with 16 laboratories from 8 European countries. The modification included a differential-elective medium for the isolation of E. sakazakii, consisting of nutrient agar (NA) supplemented with 4-methyl-umbelliferyl alpha-D-glucoside (alpha-MUG). A 25 g sample was added to 225 mL buffered peptone water. After incubation at 35 degrees or 37 degrees C for 16 or 20 h, 10 mL nonselective enrichment was transferred into 90 mL selective enrichment. The selective enrichment was streaked on violet-red bile glucose agar (VRBGA) and incubated at 37 degrees C for 24 h. It was streaked in parallel on NA plates supplemented with alpha-MUG at 50 mg/L and incubated at 25 degrees C for 16 h, and afterwards for an additional 24 h at room temperature in the dark. E. sakazakii appeared as vivid yellow colonies under normal light and showed blue/violet fluorescence under UV light on NA + alpha-MUG plates. Validation samples represented powdered infant formula without E. sakazakii (blanks) and with low (1-10 colony-forming units [CFU]/25 g) and medium (1-10 CFU/g) contamination levels. All samples contained Pseudomonas aeruginosa and Lactobacillus spp. as background flora. The specificity for blank samples was 100%. The sensitivity of the low contamination level was similar for VRBGA and NA + alpha-MUG, i.e., 66.7% (66.7% accordance, 53.9% concordance). For the medium level the sensitivities were 96.7% (93.3% accordance, 93.5% concordance) for VRBGA and 98.3% (96.9% accordance, 96.9% concordance) for NA + alpha-MUG.

Child↗
PubMed2004

Impact of genetically modified Enterobacter cloacae on indigenous endophytic community of Citrus sinensis seedlings.

Enterobacter cloacae (strain PR2/7), a genetically modified endophyte (GME) in citrus plants, carrying different plasmids (pEC3.0/18, pCelE, pEglA and pGFP), was inoculated into Citrus sinensis seedlings under greenhouse conditions. The impact of this on the indigenous bacterial endophytic community was studied by analyses of 2 different morphologic groups. The germination rates of inoculated seeds were evaluated in greenhouse, and plasmid stability under in vitro conditions. Results demonstrated a great and diverse endophytic community inside plants, and specialization in tissue colonization by some bacterial groups, in different treatments. Shifts in seed germination rate were observed among treatments: in general, the PR2/7 harboring pEglA bacterial clone significantly reduced seed germination, compared to the PR2/7 harboring pEC3.0/18 clone. This suggests that the presence of the pEglA plasmid changes bacteria-seed interactions. The endophytic community of citrus seedlings changed according to treatment. In seedlings treated with the PR2/7 with pEglA clone, the population of group II decreased significantly, within the context of the total endophytic community. These results indicate that the application of GMEs induces shifts in the endophytic bacterial community of citrus seedlings.

Bacteria↗
PubMed2004

Effect of cefoxitin and clindamycin on selection of derepressed mutants in Enterobacter cloacae.

The characteristics of an antibiotic that favor its ability to select for resistant bacteria are not completely understood. Otherwise, by the common use of broad-spectrum cephalosporins, resistant strains of several gram-negative species, especially Enterobacter cloacae, have been more frequently isolated. During our studies on beta-lactam resistance in E. cloacae, we observed that the addition of an inhibitor (clindamycin) to a potent inducer (cefoxitin) leads to an enhanced selection of resistant mutants. This could explain the emergence of beta-lactam resistant strains during antibiotic therapy.

Anti-Bacterial Agents↗
PubMed2005

Characterization of an exopolysaccharide produced by a marine Enterobacter cloacae.

An exopolysaccharide producing marine bacterium, Enterobacter cloacae, was isolated from marine sediment collected from Gujarat coast, India. Chemical investigation of exopolysaccharide (EPS 71 a) revealed that this exopolysaccharide was an acidic polysaccliaride containing high amount of uronic acid, fucose and sulfate which is rare for bacterial exopolysaccharides. EPS 71a was found to have fucose, galactose, glucose and glucuronic acid in a molar ratio of 2: 1: 1: 1.

Chromatography, Gas↗