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[The occurrence of the Enterobacter genus rods in the clinical materials and materials taken from hospital environment].

Due to continuously existing essential meaning of strains of Enterobacter spp. in human infections we investigated the occurrence of Enterobacter spp. in different clinical materials and in materials taken from hospital environment. Amongst 26,025 materials taken from patients there were 249 (1.0%) Enterobacter strains and respectively amongst 954 environmental materials--there were 11 (1.2%) Enterobacter spp. In isolated Enterobacter strains the percentage occurrence was: hospital materials: E. cloacae--65.6%, E. agglomerans--12.1%, E. aerogenes--6.25%, E. sakazakii--5.4%, E. gergoviae--1.3%, E. amnigenus--0.9%, E. intermedius--0.9% and Enterobacter spp.--7.6%; outpatient materials: E. cloacae--72.0%, E. sakazakii--12.0%, E. agglomerans--8.0%, E. aerogenes--4.0% and E. amnigenus--4.0%; hospital community: E. cloacae--63.6%, E. agglomerans--18.2% and E. sakazakii--18.2%.

Enterobacter↗

Klebsiella and Enterobacter strains derived from hospital infections. I. Correlation between species, phage type and antibiotic sensitivity.

Four hundred and seventy Klebsiella and 103 Enterobacter strains derived from urogenital infections, upper respiratory tract and wound infections were examined. (i) K. aerogenes was the most common among Klebsiella species, K. ozaenae and K. atlantae occurred frequently, K. pneumoniae, K. rhinoscleromatis, K. edwardsii and K. oxytoca were found rarely. The strains isolated from urine showed the most heterogeneous species distribution. Enterobacter species were in the order of frequency E. cloacae, E. liquefaciens, E. aerogenes. (ii) K. aerogenes strains belonged to 10, K. atlantae strains to 6 phage types; phage type II.A1 was the most frequent phage types. Typability varied between 23.7% and 48.0% with the different Klebsiella species, except K. edwardsii and K. oxytoca strains. None of the strains of these species were typable by phages. Among the Enterobacter species examined, only one E. liquefaciens strain was typable by phages. Strains of genus Enterobacter were lysed by the diagnostic phage C14 in 64%, no lysis was observed in the strains of genus Klebsiella. (iii) Multiple resistance was demonstrated in 36.6% of Klebsiella strains and in 16.5% of Enterobacter strains. The majority of the multiresistant strains was isolated from urine in both genera. Multiresistant strains belonged to the species K. aerogenes, E. cloacae and E. liquefaciens. Strains resistant to ampicillin were divided into 6 groups on the basis of cephaloridine and cephalothin resistance. The rate of multiresistant strains was higher among the Klebsiella and Enterobacter strains not typable by phages than in the typable ones.

Anti-Bacterial Agents↗

Enterobacter radicincitans sp. nov., a plant growth promoting species of the family Enterobacteriaceae.

A plant growth promoting bacterial isolate (D5/23T) from the phyllosphere of winter wheat, able to fix atmospheric nitrogen and to produce auxines and cytokinins was investigated in a polyphasic taxonomy approach. Phylogenetic analyses using the 16S rRNA gene sequence of the strain clearly indicated that the strain belonged to the family Enterobacteriaceae, most closely related to Enterobacter cloacae with 99.0% and Enterobacter dissolvens with 98.5% sequence similarity. Phylogenetic analysis derived from the sequence of the rpoB gene showed the highest sequence similarities to Enterobacter cowanii (93.0%) but supported the distinct position of strain D5/23T. The isolate produced a fatty acid pattern typical for members of the family Enterobacteriaceae. On the basis of the phylogenetic analyses, DNA-DNA hybridizations, and the unique physiological and biochemical characteristics, we propose that strain D5/23T represents a new species of the genus Enterobacter for which we propose the name Enterobacter radicincitans sp. nov.

Bacterial Typing Techniques↗

Sustained activity and spectrum of selected extended-spectrum beta-lactams (carbapenems and cefepime) against Enterobacter spp. and ESBL-producing Klebsiella spp.: report from the SENTRY antimicrobial surveillance program (USA, 1997-2000).

Enterobacter spp. and Klebsiella spp. are important clinical pathogens that frequently exhibit resistance to third-generation cephalosporins. In Enterobacter spp. strains, resistance is usually due to derepression of the Amp C locus, whereas plasmid-encoded extended-spectrum beta-lactamases (ESBLs) are primarily responsible for resistance in Klebsiella spp. Here we report the results from the SENTRY Antimicrobial Surveillance Program concerning the rates and trends of resistance to extended-spectrum beta-lactams and other antimicrobial agents in Enterobacter spp. and Klebsiella spp. isolated between 1997 and 2000 in participating hospitals in the United States. Among Enterobacter spp., resistance (MIC>or=32 mg/l) to aztreonam, ceftazidime and ceftriaxone ranged from 12.3 to 21.2% over the 4 years, whereas resistance in Klebsiella (MIC>or=2 mg/l) ranged from 5.9 to 6.8%. There was no trend toward increased resistance to these beta-lactam agents over the monitored period. Carbapenems (imipenem, meropenem) and cefepime had excellent activity against both ceftazidime-susceptible and -resistant Enterobacter spp. and Klebsiella spp. (>99% susceptible), although the minimum inhibitory concentration values of cefepime were higher in ceftazidime-resistant isolates compared with ceftazidime-susceptible isolates. Co-resistance to other antimicrobial agents was common in both tested genus groups.

Carbapenems↗

Nosocomial enterobacter meningitis: risk factors, management, and treatment outcomes.

Enterobacter species are increasingly a cause of nosocomial meningitis among neurosurgery patients, but risk factors for these infections are not well defined. A review of all adult patients hospitalized at the University of California-Los Angeles (UCLA) Medical Center during an 8-year period identified 15 postneurosurgical cases of Enterobacter meningitis (EM). Cure was achieved in 14 cases (93%), and efficacy was similar for carbapenem- and cephalosporin-based treatment. A matched case-control study comparing 26 controls with 13 case patients hospitalized exclusively at the UCLA Medical Center found that external cerebrospinal fluid (CSF) drainage devices (odds ratio [OR], 21.8; P=.001), isolation of Enterobacter species from a non-CSF culture (OR, 24.6; P=.002), and prolonged administration of antimicrobial drugs before the diagnosis of meningitis that were inactive in vitro against Enterobacter species (OR, 13.3; P=.008) were independent risk factors for EM. Despite favorable treatment outcomes, EM is a serious infection associated with Enterobacter species colonization or infection at other surgical sites, with selective antimicrobial pressure, and with invasive CNS devices.

Adult↗

Association between climate and Enterobacter colonization in Swedish neonatal units.

OBJECTIVE: To study risk factors for the highly variable local colonization rates with unrelated Enterobacter species strains previously found in 22 Swedish neonatal units (0% to 32.4% of the infants). PATIENTS AND SETTING: The fecal Enterobacter species carriage rates among 953 infants in the 22 special-care neonatal units were correlated with variables related to the ward (size, crowding, staffing, work load, antibiotic usage, level of care, hygienic precautions), and the hospital (temperature of water supplied, geographical location). RESULTS: The average Enterobacter species carriage rate was highest at seven days of age (17% of the infants) and then declined to 3%. Only location of the hospital in an area with warmer climate according to horticultural zone showed an association with Enterobacter species carriage in multivariate analysis (P = 0.005). CONCLUSION: Although Enterobacter species mainly cause nosocomially acquired infections, the occurrence of the organism in special-care neonatal units seemed to be determined more by extrahospital than by intrahospital factors.

Carrier State↗

Enterobacter bacteremia in pediatric patients.

Enterobacter has emerged as an important human pathogen, particularly in sick, hospitalized patients. Previous reports of nonepidemic enterobacter bacteremia have focused on adult patients. In this report, the epidemiologic factors, clinical characteristics, treatment, and outcome for 33 patients with enterobacter bacteremia in a large children's hospital during a 5-year period are reviewed. The ratio of males to females was 1.2:1. The patients' ages ranged from 2 days to 24 years, and 18 patients were less than 18 months old. Twenty-two cases were nosocomially acquired; six were polymicrobial in nature. Significantly underlying conditions were present in 32 patients. The biliary tract and central venous catheters were the most common sources of bacteremia. Two-thirds of patients had preceding antibiotic therapy. The overall mortality was 24%; mortality attributable to enterobacter bacteremia was 18%. Statistically significant differences in mortality were associated with an age less than 18 months (P = .031) or thrombocytopenia (P = .017); presence of fever was of borderline significance (P = .098). Enterobacter bacteremia is an important cause of morbidity and mortality in pediatric patients.

Adolescent↗

Beta-lactam-resistant Enterobacter bacteremia in febrile neutropenic patients receiving monotherapy.

Bacteremia with resistant Enterobacter species has been reported in febrile, neutropenic cancer patients receiving beta-lactam antibiotics. To assess the relationship between enterobacter bacteremia and ceftazidime monotherapy, medical records were reviewed and isolates were tested from 16 neutropenic and 35 nonneutropenic patients with Enterobacter bacteremia. Fifteen isolates from the neutropenic patients were resistant to extended spectrum cephalosporins; only 12 of 35 isolates from the nonneutropenic patients were resistant to Enterobacter species. The neutropenic patients also had more beta-lactam therapy, both immediately before bacteremia and in the preceding year, than did nonneutropenic patients. Prior beta-lactam antibiotic exposure may predispose neutropenic patients to develop resistant Enterobacter bacteremia.

Adolescent↗

Enterobacter hormaechei, a new species of the family Enterobacteriaceae formerly known as enteric group 75.

The name Enterobacter hormaechei is proposed for a new species of the family Enterobacteriaceae, formerly called Enteric Group 75, which consists of 23 strains, 22 of which were isolated from humans. DNAs from 12 E. hormaechei strains tested were highly related to the type strain (ATCC 49162) by DNA hybridization, using the hydroxyapatite method (80 to 97% in 60 degrees C reactions; 80 to 90% in 75 degrees C reactions). The strains were most closely related (50 to 63%) to Enterobacter cloacae, Enterobacter dissolvens, Enterobacter taylorae, and Enterobacter nimipressuralis. E. hormaechei strains were positive within 48 h for the following: Voges-Proskauer test; citrate utilization (Simmons and Christensen); urea hydrolysis (87%); ornithine decarboxylase; growth in potassium cyanide (KCN); malonate utilization; production of acid from D-glucose, L-arabinose, cellobiose, dulcitol (87%), D-galactose, maltose, D-mannitol, D-mannose, L-rhamnose, sucrose, trehalose, and D-xylose; acid production from mucate; nitrate reduction; and o-nitrophenyl-beta-D-galactopyranoside. Delayed positive reactions were seen in tests for arginine dihydrolase, gas from D-glucose, acid from alpha-methyl-D-glucoside, and acetate utilization. E. hormaechei was negative in tests for indole production; H2S production; phenylalanine deaminase; lysine decarboxylase; gelatin hydrolysis; acid production from D-adonitol, D-arabitol, erythritol, glycerol, i(myo)-inositol, melibiose, raffinose, and D-sorbitol; esculin hydrolysis; DNase; lipase; and tyrosine clearing. Variable reactions occurred in tests for methyl red, motility, and tartrate. All strains tested were susceptible or moderately susceptible to amikacin, azlocillin, cefotaxime, ceftazidime, ceftriaxone, chloramphenicol, gentamicin, mezlocillin, moxalactam, piperacillin, trimethoprim-sulfamethoxazole, sulfisoxazole, thienamycin, tobramycin, and trimethoprim. All strains tested were resistant to nitrofurantoin; the majority were resistant to ampicillin, cefoxitin, and cephalothin. Four isolates were from blood; most other isolates were from wounds or sputum.

Adolescent↗

Involvement of gacS and rpoS in enhancement of the plant growth-promoting capabilities of Enterobacter cloacae CAL2 and UW4.

The plant growth-promoting bacteria Enterobacter cloacae CAL2 and UW4 were genetically transformed with a multicopy plasmid containing an rpoS or gacS gene from Pseudomonas fluorescens. The transformed strains were compared with the nontransformed strains for growth, indoleacetic acid (IAA) production, antibiotic production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, siderophore production, cell morphology, and the ability to promote canola root elongation. All transformed strains had a longer lag phase, were slower in reaching stationary phase, and attained a higher cell density than the nontransformed strains. Transformation resulted in cells that were significantly shorter than the nontransformed cells. The transformed strains also produced significantly more IAA than the nontransformed strains. Introduction of rpoS or gacS from Pseudomonas fluorescens was associated with a reduction in the production of both antibiotics, 2,4-diacetylphloroglucinol and mono-acetylphloroglucinol, produced by Enterobacter cloacae CAL2. With Enterobacter cloacae CAL2, plasmid-borne rpoS, but not gacS, increased the level of ACC deaminase activity, while introduction of rpoS in Enterobacter cloacae UW4 caused a decrease in ACC deaminase activity. Neither gacS nor rpoS significantly affected the level of siderophores synthesized by either bacterial strain. Overproduction of either GacA or RpoS in Enterobacter cloacae CAL2 resulted in a significant increase in the root lengths of canola seedlings when seeds were treated with the bacteria, and overproduction of RpoS caused an increase in canola shoot as well as root lengths.

Anti-Bacterial Agents↗

Enterobacter spp. infections complicating the course of HIV disease.

Through a retrospective review of clinical and laboratory data of 2517 consecutive patients with HIV disease hospitalized since 1991, 13 patients were identified (0.52%), who suffered from a confirmed Enterobacter spp. infection (urinary tract disease in 7 cases, sepsis in 4 patients, and pneumonia in 2 cases). A severe immunodeficiency was recognized in all cases, as expressed by a mean CD4+ lymphocyte count <60 cells/microL, and frequently, a prior diagnosis of AIDS. Bloodstream infection proved linked to a lower mean CD4+ cell count, a more frequent occurrence of leukopenia-neutropenia, and nosocomial origin of the infecting pathogen. Hospital-acquired Enterobacter spp. disease was more frequent than community-acquired, and was significantly associated with leukopenia-neutropenia, and a diagnosis of AIDS. Antibiotic susceptibility assays showed a resistance rate to ampicillin and cephalothin involving >90% of tested strains, and a higher (but varied) sensitivity to other beta-lactams, aminoglycosides, fluoroquinolones, and cotrimoxazole. Adequate chemotherapy provided clinical and bacteriological success in all evaluated patients, in the absence of mortality or relapses. Only 34 episodes of HIV-associated Enterobacter spp. infection have been reported to date in 11 different literature studies. Our data point out that also Enterobacter spp. organisms may have an appreciable pathogenic potential in patients with HIV disease, especially in those with a low CD4+ lymphocyte count, leukopenia-neutropenia, who are hospitalized. Despite the unpredictable antibiotic susceptibility profile of these organisms, HIV-related Enterobacter spp. disease may be properly managed through rapid identification and timely and appropriate antimicrobial treatment.

Adult↗

Production of 2,3-butylene glycol from whey by Klebsiella pneumoniae and Enterobacter aerogenes.

Production of 2,3-butylene glycol from whey with Klebsiella pneumoniae and Enterobacter aerogenes was studied. Sterilization of the whey was unnecessary. Acid whey required neutralization, but sweet whey did not. Butylene glycol production was most efficient at 33 degrees C for Klebsiella pneumoniae and at 37 degrees C for Enterobacter aerogenes. Aeration significantly improved yields. Klebsiella pneumoniae produced more butylene glycol than did Enterobacter aerogenes in unsupplemented whey. The addition of 50 mM sodium acetate to whey increased the production of butylene glycol and acetoin by Enterobacter aerogenes; it also increased the production of glycol by Klebsiella pneumoniae, but the increase in this case was offset by a decrease of production of acetoin. Maximal yields of the glycol plus acetoin in whey were obtained in 48 to 64 h, but Enterobacter aerogenes required about 160 h for complete utilization of the lactose. Highest yields were about .3 M butylene glycol plus acetoin, which corresponds to the production of about 10 kg of glycol from 380 liters of whey.

Acetoin↗

Enterobacter bacteremia.

OBJECTIVES: To study the incidence, antimicrobial susceptibility pattern, age and sex distribution, mortality and prognostic factors in cases of Enterobacter bacteremia. METHODS: A total of 18,745 indoor patients with suspected bacteremia were included in study. Enterobacter spp were identified and speciated using standard protocols. Antimicrobial susceptibility testing was done using Stoke's disc diffusion method and minimum inhibitory concentration (MIC) was determined by agar dilution method as recommended by NCCLS. RESULTS: Enterobacter spp ranking sixth was responsible for 4.6% of total group of significant bacteremias. The species most commonly causing bacteremia was E. cloacae (61.8%). The bacteremia was unimicrobial in 85.1% and part of a polymicrobial bacteremia in 14.8%. Portal of entry in decreasing order of frequency were unknown, respiratory tract, urinary tract and surgical wound. The most common clinical finding was fever (97.2%). Of Enterobacter isolates 72.9% were multiresistant to three or more antimicrobial agents. Overall mortality was 51.1%. CONCLUSION: Enterobacter spp are becoming increasingly important nosocomial pathogens. To prevent further emergence of multidrug resistance it may beprudent to avoid third generation cephalosporins and instead combination therapy may be used.

Adolescent↗

[Nosocomial bacteremia caused by Enterobacter spp.: epidemiology and prognostic factors].

BACKGROUND: The aim of this study was to establish the clinical and epidemiologic features of nosocomial bacteremia by Enterobacter spp. and to analyse its prognostic factors. METHODS: A prospective study of the episodes of nosocomial bacteremia by Enterobacter spp. with clinical significance, detected in a third level university hospital from January 1984 to December 1990 was performed. RESULTS: During the study period, 226 episodes of bacteremia by Enterobacter spp., of which 184 (81%) were of nosocomial origin (8.1% of all the nosocomial bacteremias), while 14% were polymicrobial. An increasing trend was observed in the number of episodes (1984 vs 1990) from 0.9 vs 1.8 episodes per 1,000 admissions, respectively. The mean age was 57 years and the male/female relation was 2.4/1. The most frequent focus of origin was infection of the vascular catheter (43%), followed by intraabdominal catheter (21%), urinary tract (14%), and other foci (17%). Fifty-four percent of the patients had received antibiotics prior to the episode of bacteremia. Most of the cases were detected in the Intensive Care Units (ICU) (41%) and in the gastrointestinal surgery area (24%). Global mortality was 23%. Logistic regression analysis selected an entry site other than infection of the vascular catheter (odds ratio 6.1; CI [95%)] 2.0-18.4), shock (odds ratio, 6; CI [95%], 1.6-21.9) and immunosuppressive treatment (odds ratio, 5; CI [95%], 1.5-16.2) as independent variables of bad prognosis. CONCLUSIONS: Enterobacter spp. is an important nosocomial pathogen taking fourth place in the ranking of nosocomial bacteremia by gram negative bacilli. It predominantly affects a population of patients admitted in the ICU and surgery. The intravascular catheter is a frequent entry site for nosocomial bacteremia by Enterobacter spp.

Adult↗

The clinical relevance of Enterobacter infections.

An 18-month prospective study of Enterobacter bacteremia was conducted in 129 patients. The results indicated that (1) emergence of resistance was more frequent during treatment with third-generation cephalosporins than with other antibiotics; (2) the addition of an aminoglycoside to the cephalosporin did not prevent emergence of resistance; (3) previous treatment with cephalosporins was associated with bacteremia caused by multiresistant Enterobacter species; and (4) infection with multiresistant Enterobacter species was associated with a higher mortality than infection with susceptible strains. It is concluded that avoidance of third-generation cephalosporins for surgical prophylaxis and therapy in patients in whom Enterobacter infections are suspected or proven should lower the prevalence of Enterobacter bacteremias and mortality and prevent the emergence of multiresistance.

Adolescent↗

Infections with gram-negative bacilli in a cardiac surgery intensive care unit: the relative role of enterobacter.

A 7-month prospective survey for cefazolin-resistant Gram-negative bacilli in cardiac surgery patients, receiving cefazolin prophylaxis, showed that 58 (67%) of 87 were colonized with enterobacter, 37 (64%) with citrobacter, 33 (57%) with Pseudomonas aeruginosa, and seven (2%) with Serratia marcescens. About 50% of colonization occurred before cefazolin prophylaxis and was present on admission to the intensive care unit. Typing of strains showed that horizontal transmission accounted for at most 14% of carriage. Cefazolin prophylaxis (and high gastric pH) were associated with increased levels of postoperative colonization, most notably for enterobacter. About 25% of colonization with enterobacter, pseudomonas, and serratia was followed by clinical infection. Enterobacter cloacae was the most common pathogen and pneumonia the most common infection. Infections contributed to eight of 11 deaths; four of the eight involved enterobacter. Potential control measures include eliminating endogenous Gram-negative flora by gut decontamination or at least stemming the increase in level of colonization that occurred after surgery.

Adult↗

Enterobacter sepsis in the newborn--a growing problem in Karachi.

Enterobacter sepsis is commonly recognized as a hospital-acquired infection in childhood. In a five year prospective surveillance of neonatal sepsis at the Aga Khan University Hospital in Karachi, we identified Enterobacter sepsis in 28/292 (10%) cases, with an incidence of 0.7 per thousand births among inborn infants. There was no significant difference in predisposing factors and clinical features between Enterobacter and other infections. Approximately half (47%) of Enterobacter infections presented within 72 h of birth and the associated mortality was 21%. Increasing resistance to commonly used first- and second-line antibiotics over the last five years was noted. Enterobacter infections are emerging as significant pathogens among cases of neonatal sepsis in Karachi.

Case-Control Studies↗

DNA relatedness among species of Enterobacter and Serratia.

Species of Enterobacter and Serratia were examined for deoxyribonucleic acid relatedness to Klebsielleae, to atypical erwiniae, and to other members of Enterobacteriaceae. Deoxyribonucleic acid hybridization and then hydroxyapatite chromatography was the technique used to assess relatedness. Strains of Enterobacter cloacae formed two separate hybridization groups that correlate with the presence or absence of yellow pigment. Pigmented E. cloacae were 75-100% related, but they were only 40-50% related to unpigmented strains. Conversely, unpigmented strains were 70% or more related but were only 40-50% related to the pigmented strains. Both pigmented and unpigmented E. cloacae were 40-45% related to Enterobacter aerogenes and klebsiellae, and 20-30% related to Serratia species and Enterobacter hafniae. Atypical erwiniae were highly related to E. cloacae. Serratia marcescens strains formed one closely related group. Serratia liquefaciens strains formed a single, more disperse, relatedness group, as did isolates of Serratia rubidaea. These species were related throughout a substantial portion of their genomes. A group of lysine-positive "Citrobacter-like" strains were 40-50% related to Serratia species. Only four E. hafniae strains were tested. Two of these were highly related, while the other two were only 50% related to the reference strain. Enterobacter hafniae was only 15-20% related to other Enterobacteriaceae.

DNA, Bacterial↗