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PubMed1985

Ways to overcome cephalosporinase-mediated beta-lactam resistance in Enterobacter cloacae.

Beta-lactam antibiotics which affect mainly PBP 3 and are poor substrates for the cephalosporinase of Enterobacter cloacae, but tightly bind to it, are not active against cephalosporinase-overproducing variants of this organism. Attempts have been made to greatly reduce the affinity for the beta-lactamase in order to prevent both binding and hydrolysis. 3-Quaternary ammonium cephalosporins and some cephalosporin (S)-sulfoxides were seen to fit this requirement. Suitable substitution of the monocyclic beta-lactam nucleus also resulted in compounds with lower affinity than aztreonam. Temocillin, differing from ticarcillin by the 6-methoxy group, also has a lower affinity for the cephalosporinase. All compounds discussed retain the highest affinity for PBP 3 and are active against cephalosporinase-overproducing E. cloacae in contrast to compounds with high affinity for the cephalosporinase.

Anti-Bacterial Agents↗
PubMed1985

Properties of Sepharose-bound beta-lactamase from Enterobacter cloacae.

beta-Lactamase from Enterobacter cloacae P99 was immobilized onto Sepharose by the cyanogen bromide activation method and the properties of the Sepharose-bound enzyme were compared with those of soluble and cell-bound enzyme. The immobilized beta-lactamase showed enhanced stability to storage at 4 degrees C (approximately 1 year) in respect to the free enzyme in solution (few days). The optimum pH for activity is similar for both Sepharose- and cell-bound beta-lactamase and extends over a broader pH range (pH 6-9) than the soluble enzyme (pH 8-9). Immobilization leads also to significant enhancement of thermal stability. Effective enzyme inhibition by flucloxacillin occurs with both soluble and Sepharose-bound beta-lactamase, whereas the cell-bound enzyme is much less (10(-5) times) inhibited. These results indicate that immobilized beta-lactamase could be usefully employed as a tool for investigating the properties of newly designed beta-lactamase inhibitors.

Cyanogen Bromide↗
PubMed1979

Differential survival of Salmonella typhi, Escherichia coli, and Enterobacter aerogenes on lettuce in the field.

Artificial contamination of young lettuce plants with Salmonella typhi (ST), Escherichia coli (EC), and Enterobacter aerogenes (EA) in the field in winter and summer resulted in presence of the pathogen and increased density of the two indicator bacteria (IB) in harvested produce. Viable counts of the three bacteria/g fresh weight declined at a decreasing rate with increasing time after contamination. The overall pattern of variation of the ST/IB ratio was correlated more closely with changes in the ST/EA than in the ST/EC ratio values. When viable counts were expressed as a proportion of the contaminating dose at different times after contamination, however, a closer similarity existed between ST and EC than between ST and EA values throughout winter and through the early part of summer experiments.

Enterobacter↗
PubMed1985

Occurrence of cefotaxime-resistant Enterobacter during therapy of cardiac surgery patients.

During 1981-1984, nine patients were treated with second or third generation cephalosporins for deep post-operative wound, respiratory, and blood infections with Enterobacter. In at least 50-60% of cases, therapy failed due to emergence of broad-spectrum cephalosporin resistance. Laboratory testing of two strains that became resistant showed that they were more likely to develop high level resistant mutants, which had greater ability to bind cefotaxime. Although these surgery patients represent an extreme case, spread of their resistant strains to other patients in hospital could lead to wide-spread nosocomial resistance.

Cardiac Surgical Procedures↗
PubMed1985

Epidemiological study of Enterobacter cloacae resistant to 3rd generation cephalosporins: a preliminary report.

In 1983 an increase in the resistance rate of cefotaxime against Enterobacter cloacae strains was observed in "Laikos General" hospital, that reached 59.3% in the 2nd half of the same year. All strains resistant to cefotaxime were found resistant to cefamandole, moxalactam and ceftriaxone while 61.8% were also resistant to amikacin. Urine represented the main source of isolation, particularly from the catheterized patient of the Renal Transplantation Unit in whom cefuroxime was mostly over used. Multiresistant strains were virulent since 5 patients died of septicemia. Mechanisms of resistance to cefotaxime are speculated upon because resistance work-up has not yet been completed. SHV, was exclusively isolated in the limited number of strains which have been studied up to now.

Cephalosporins↗
PubMed1979

[Study of a new group of Enterobacteriacea (group H1) related to Enterobacter cloacae strain].

A DNA-DNA hybridization study was carried out on a new group of enterobacteria (group H1) previously studied by numerical taxonomy work on the genus Enterobacter. This group showed a very high genetic homogeneity since the average relative binding ratio of nine analysed strains is equal to 91%. The taxonomic position of this group into the family of enterobacteria is discussed with the species E. cloacae (37 to 61%), K. pneumoniae (44 to 60%), K. oxytoca (57-58%), L. malonatica (syn. Citrobacter intermedius, a:46 to 54%), L. amalonatica (syn. C. intermedius, b: 51%), and the group H3 (52-61%). The group H1 is defined on phenotypic and genetic data.

DNA, Bacterial↗
PubMed1979

[Detection and significance of histidine decarboxylase (HDC) in "Klebsiella", "Enterobacter" and "Serratia" (author's transl)].

A quick colorimetric procedure for detection of histidine decarboxylase (HDC) in cultures of Klebsiella, Enterobacter and Serratia is described. Only E. aerogenes could decarboxylate histidine (production of histamine). The interest of HDC test for differentiation of E. aerogenes from K. pneumoniae (especially urease negative strains) is discussed.

Carboxy-Lyases↗
PubMed1984

[Isolation and properties of beta-lactamase of the cephalosporinase type from cells of Enterobacter aerogenes 6803].

beta-Lastamase with the molecular weight of 32500 was isolated from the cells of clinical strain 6803 of Enterobacter aerogenes and purified. By the substrate profile determined microiodometrically beta-lactamase was classified as belonging to the cephalosporinase type. The activity of the electrophoretically homogenous enzyme was equal to 430 microM a minute per mg protein with respect to benzylpenicillin. The Km for benzylpenicillin, dicloxacillin, cephaloridin and cephalothin was 6.5410(-5), 3 X 10(-4), 2.1 X 10(-5) and 5.7 X 10(-5) M, respectively. The isoelectric point of the enzyme equal to 5.45 was estimated with the method of preparative isoelectrofocusing. The presence of the serine residue or residues was shown with the use of selective reagents applied to the functionally important groups. With the method of circular dichroism the ratio of alpha- and beta-structures in the enzyme molecule was determined, the slow hydrolysis of cephazolin was demonstrated and the values of Km and Kcat for this process were estimated.

Cephalosporinase↗
PubMed1984

Cholecystitis associated with Enterobacter agglomerans.

A case report of chronic cholecystitis due to Enterobacter agglomerans, occurred in a 54-year old female with homozygous beta-thalassemia. The patient responded successfully to cholecystectomy and sulfamethoxazole + trimetroprim therapy. The source of the infection was not known, however, cystic duct obstruction and immune deficit were thought to be the predisposing causes.

Cholecystectomy↗
PubMed1983

[Change in the vaginal smear cycle following conventionalization and monocontamination of germ-free rats with Enterobacter cloacae].

The relationship between the microbial organism infection and the vaginal smear cycle was investigated using 12 germfree Wistar Imamichi rats at 50 days of age. Germfree rats exhibited continuous vaginal cornification which occasionally interrupted by the appearance of nucleated epithelial cells. However, leukocytes which are characteristic of the metestrus and diestrus stage in conventional rats were not observed in the vaginal smear of these animals. At 70 days of age, 8 animals were taken out from the germfree isolator and conventionalized. In other 4 animals, the vaginal lumen was contaminated with Enterobacter cloacae in the isolator. Within 3 days after the treatments, leukocytes appeared in the vaginal smear of all animals in both groups. Thereafter, these animals continued the regular 4 days vaginal cycle to 90 days of age, at which the observation was terminated. The above results suggested that the appearance of leukocytes in the vaginal smear in the rat is closely related to the bacterial colonization in the lumen, together with the action of the progesterone secreted from the ovary.

Age Factors↗
PubMed1982

Population analysis of sensitivity to ampicillin and carbenicillin in Eschericia coli and Enterobacter cloacae.

Population analysis of sensitivity to ampicillin (A) and carbenicillin (Ca) was carried out with four strains of E. coli and five strains of Enterobacter cloacae. The two A-sensitive/Ca-sensitive (A-s/Ca-s) E. coli strains were homogeneous as regards A-sensitivity. From the A-resistant/Ca-s (A-r/Ca-s) E. coli strains, it was possible to select A-r/Ca-r mutants. Mutation frequency approx. 10-7.5. When the inoculum of A-s/Ca-s E. coli was raised, it was possible to select A-r/Ca-s/cephalothin-r variants with a frequency of approx. 10-9.7. In this laboratory 5% (10-1.3) of the received E. coli strains are A-r/Ca-s. These strains might consequently be mutants of the usual A-s/Ca-s E. coli, selected in an ampicillin environment. The two A-s/Ca-s E. cloacae strains developed mutants highly resistant to A, thereby differing from the A-s/Ca-s E. coli strains. The mutation frequency was approx. 10-7.2. Likewise it was possible to select A-r/Ca-r E. cloacae strains from the usual A-r/Ca-s ones. Mutation rate approx. 10-6.8.

Ampicillin↗
PubMed1980

[Distinctive profiles of esterases from Klebsiella pneumoniae, K. oxytoca, Enterobacter aerogenes and E. gergovia].

Cellular esterases of 14 strains of Klebsiella pneumoniae, 14 strains of K. oxytoca, 16 strains of Enterobacter aerogenes and 16 strains of E. gergoviae were analysed by polyacrylamide-agarose gel and polyacrylamide gradient gel electrophoresis. Four principal esterase bands and nine minor bands, differing in their activity towards synthetic substrates and in their sensitivity to heat and to di-isofluoropropyl phosphate (DEP) were defined. The comparative distribution of bands showed that the four species analysed were characterized by distinct electrophoretic patterns of their esterases.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

[Decarboxylase activity of bacteria of the genus Enterobacter depending on the growing conditions].

The activity of decarboxylase in the cells of two bacterial species belonging to the genus Enterobacter was found to depend on the carbon source of the growth medium and on the substrate used to determine the enzyme activity. Cells grown on a medium containing glucose and incubated in solutions of glucose and sodium pyruvate produced 1.4 to 2.1 times more CO2 than cells utilizing glycerol. The highest amount of CO2 was formed on pyruvate, the substrate of the first reaction of decarboxylation.

Acetoin↗
PubMed1982

Resistance types in Enterobacter cloacae. Occurrence and resistance to Ampicillin, Carbenicillin, Cephalothin and Mecillinam. Transfer of ampicillin Resistance.

An investigation of the resistance types in Enterobacter cloacae is presented. The frequency of the different resistance types was determined. The strains were divided into three groups according to sensitivity to penicillin derivatives. The ampicillin-carbenicillin-sensitive (A-s/Ca-s) group 1 comprised 20% of the E. cloacae strains received in this laboratory. The ampicillin resistant-carbenicillin-sensitive (A-r/Ca-s) group 2 comprised 38.5% of the strains and the A-r/Ca-r group 3 comprised 41.5% of the strains. Group 3 contained a high proportion of multi-resistant strains. The log 2 IC50 against ampicillin, carbenicillin, cephalothin and mecillinam was determined for 28 strains. The group 3 strains were more ampicillin-resistant than the group 2 ones. Group 1 and 2 did not differ as regards carbenicillin sensitivity. The cephalothin resistance increased from group 1 to group 2 and further on to group 3. Mecillinam sensitivity did not differ between the three groups. The ability to transfer ampicillin resistance was investigated in the 24 A-r strains. The 8 group 2 strains were not able to transfer resistance, while 9 of 16 strains in groups 3 could transfer A-resistance with frequencies ranging from 10-0.2 to 10-5.7. Resistance to sulphonamide, tetracycline and streptomycin was also transferred, often with the same frequency as the ampicillin resistance.

Amdinocillin↗
PubMed1981

Enterobacter cloacae, Serratia marcescens and Yersinia enterocolitica in colonies of laboratory mice, rats and rabbits: an attempt of isolation.

An attempt to isolate Enterobacter cloacae, Serratia marcescens and Yersinia enterocolitica was made in a total of 931 laboratory animals (mice, rats and rabbits) from five representative commercial breeders in this country and from our laboratory colonies. E. cloacae organisms were isolated from feces and other specimens of 15 mice and 17 rats between November 1979 and July 1980. Neither S. marcescens nor Y. enterocolitica was detectable in any specimen of feces, fur and skin, nasal discharge, lungs, urinary bladder or urine from the animals examined.

Animals↗
PubMed1978

Enterobacter aerogenes primary bacteremia in pediatric patients.

Enterobacter aerogenes bacteremia associated with the infusion of contaminated admixed intravenous (IV) fluid occurred in seven patients in a pediatric hospital over a five-day period. Clinical illness was characterized by spiking fever in all patients. The temporal clustering of cases allowed for rapid recognition of the problem. The primary control measure was the prompt replacement of the IV fluids, although IV antibiotics were also administered. Hospital pharmacy practices for admixing IV solutions should follow published recommendations to minimize this source of potential contamination of fluids.

Child↗
PubMed1980

Necrotizing enterocolitis. Epidemic following an outbreak of Enterobacter cloacae type 3305573 in a neonatal intensive care unit.

Twelve cases of necrotizing enterocolitis (NEC) occurred within three weeks in a neonatal intensive care unit (NICU) with 325 annual admissions. Enterobacter cloacae type 3305573 was found in stool and/or blood cultures from affected babies prior to the onset of the disease. This bacterium could not be grown in cultures from infants in the same NICU six weeks later. A causal relationship between E cloacae and the epidemic of NEC is suggested.

Cross Infection↗
PubMed1978

Plasmid borne virulence of Enterobacter hafniae.

The strain classified as Enterobacter hafniae has been isolated in a severe epidemy of porcine diarrhoea. Its pathogenicity has been found to be cotransmissible with resistance to oxytetracycline when the strain was grown in a mixed culture with some nonpathogenic E. hafniae strains as well as with Escherichia coli. Toxinogenity seems to be responsible for virulence of the strain.

Animals↗