Studies on the Klebsiella-Aerobacter group of bacteria

Lactobacilli and Klebsiella: Two Opposites in the Fight for Human Health

The problem of antibiotic resistance is currently very acute. Numerous research and development of new antibacterial drugs are being carried out that could help cope with various infectious agents. One of the promising directions for the search for new antibacterial drugs is the search among the probiotic strains present in the human gastrointestinal tract. This review is devoted to characteristics of one of these probiotic strains that have been studied to date: Limosilactobacillus reuteri. The review discusses its properties, synthesis of various compounds, as well as role of this strain in modulating various systems of the human body. The review also examines key characteristics of one of the most harmful among the currently known pathogenic organisms, Klebsiella, which is significantly resistant to antibiotics existing in medical practice, and also poses a great threat of nosocomial infections. Discussion of characteristics of the two strains, which have opposite effects on human health, may help in creation of new effective antibacterial drugs without significant side effects.

Microbial utilization of the industrial wastewater pollutants 2-ethylhexylthioglycolic acid and iso-octylthioglycolic acid by aerobic gram-negative bacteria

Industrial wastewater from the production of sulfur containing esters and the resulting products of this synthesis, 2-ethylhexylthioglycolic acid (EHTG) and iso-octylthioglycolic acid (IOTG), were deployed in this study to enrich novel bacterial strains, since no wastewater and EHTG or IOTG degrading microorganisms were hitherto described or available. In addition, nothing is known about the biodegradation of these thiochemicals. The effect of this specific wastewater on the growth behaviour of microorganisms was investigated using three well-known Gram-negative bacteria (Escherichia coli, Pseudomonas putida, and Ralstonia eutropha). Concentrations of 5% (v/v) wastewater in complex media completely inhibited growth of these three bacterial strains. Six bacterial strains were successfully isolated, characterized and identified by sequencing their 16S rRNA genes. Two isolates referred to as Achromobacter sp. strain MT-E3 and Pseudomonas sp. strain MT-I1 used EHTG or IOTG, respectively, as well as the wastewater as sole source of carbon and energy for weak growth. More notably, both isolates removed these sulfur containing esters in remarkable amounts from the cultures supernatant. One further isolate was referred to as Klebsiella sp. strain 58 and exhibited an unusual high tolerance against the wastewater's toxicity without utilizing the contaminative compounds. If cultivated with gluconic acid as additional carbon source, the strain grew even in presence of more than 40% (v/v) wastewater. Three other isolates belonging to the genera Bordetella and Pseudomonas tolerated these organic sulfur compounds but showed no degradation abilities.

Lobar pneumonia in rats produced by clinical isolates of Klebsiella pneumoniae

Transtracheal instillation of clinical isolate Klebsiella pneumoniae serotype 1 (KP1) into the lungs of rats resulted in the production of a characteristic, chronic lobar pneumonia. To further examine this phenomenon, two variants of this organism were employed in this experimental model. These variants differed markedly in capsule size, colony morphology, and in virulence, as determined by mouse lethality tests. The ability of these strains to establish a lobar pneumonia in rats correlated with the virulence of the respective organisms as monitored by intraperitoneal injection in mice. The 50% lethal doses in mice were 4.9 x 10(1) colony-forming units (CFU) for the more virulent KP1 strain (KP1-O) and 1.42 x 10(5) CFU for the less virulent variant (KP1-T). In the rat lung model, marked lung pathology was evident by day 6 with a KP1-O inoculum of 5 x 10(2) CFU, whereas KP1-T caused little or no lung pathology when delivered transtracheally at a concentration of 7 x 10(6) CFU. Two relatively nonvirulent variants of K. pneumoniae serotype 2 were also used in this rat lung model and were found not to produce a lobar pneumonia even when delivered in large doses. These results indicate that a chronic lobar pneumonia can be established in a rat model if the appropriate organism is employed and the virulence of K. pneumoniae injected intraperitoneally into mice is an excellent indicator of an organism's potential to cause lobar pneumonia in rats.

Fermentation of polysaccharides by Klebsielleae and other facultative bacilli

Fermentations of 10 polysaccharides by species of the family Enterobacteriaceae were examined. Algin, guar, karaya, xanthan, and xylan were not fermented by any of the strains tested. Most of the activity was found in the tribe Klebsielleae. Klebsiella oxytoca fermented amylopectin (97% of the strains studied), carrageenan (100%), inulin (68%), polypectate (100%), and tragacanth (100%). Klebsiella pneumoniae fermented amylopectin (91%), carrageenan (100%), and tragacanth (86%). Carrageenan was also fermented by Enterobacter aerogenes (100%), Enterobacter agglomerans (63%), Enterobacter cloacae (95%), and Pectobacterium (38%). Pectobacterium shared polypectate fermentation (100%) with K. oxytoca. With one exception, Serratia strains were negative on all polysaccharides. These results, along with other evidence, indicate that (i) the genus Klebsiella is biochemically the most versatile genus of the tribe, (ii) because of its distinct characteristics, K. oxytoca warrants species designation separate from K. pneumoniae, and (iii) some food additives generally considered indigestible can be metabolized by a few species of facultative bacilli, whereas others appear to be resistant.

An investigation into the incidence and sources of klebsiella infections in hospital patients

Coliforms isolated from infections over a period of 22 months were examined and 16% were shown to be klebsiellas. The biochemical reactions and serotypes of these klebsiellas were determined and the relationship between species, serotype and type of infection investigated. Although no obvious outbreaks of infection occurred during this period a number of clusters of isolations of the same serotype of klebsiella were found. Using an enrichment method for the isolation of klebsiellas from faeces, sero and bacteriocin typing, and the examination of ten colonies, it was demonstrated that half of the patients carried a klebsiella of the same type in the bowel as caused the infection.

A new serotyping method for Klebsiella species: development of the technique

A new serotyping method for Klebsiella species using indirect immunofluorescence is described. Nonspecific fluorescence has been minimized by carrying out the capsular antigen-antibody reaction at pH 9.0. Commercial antisera have been tested with the 72 antigenic types of Klebsiella, and appropriate dilutions of each pool and specific antisera have been proposed for use in routine typing. Dilutions were chosen to allow strong fluorescence with each type and its specific antiserum and minimal fluorescence with cross reacting antisera. Where the pool antisera gave a weak reaction for one or more of the component types, it is recommended that the specific antisera for these types be added to the pool dilution. The few remaining cross reactions, with the pool and specific antisera in test dilution, are listed in a table. The unique cross reacting patterns of particular types have been found to be useful in identification. Typing Klebsiella by the fluorescent antibody technique is easy to perform and interpret; the results are reproducible, and it is less expensive than the existing capsular swelling method as it is more sensitive and requires less concentrated antisera. This new method of typing should facilitate detailed epidemiological studies of the mode of transmission of Klebsiella species in hospitals and thus allow more effective infection control measures to be instituted.

Titres and cross reactions of commercial antisera for the capsular typing of Klebsiella species

Ninety commercially supplied sera for the capsular typing of Klebsiella species were tested in a full chequerboard against 72 type strains. Only four of 144 homologous reactions could not be detected. Of the 6336 possible heterologous reactions, 91 actual cross reactions were found. All positive reactions were titrated and working dilutions deduced. This provides essential information for the successful typing of unknown strains with these sera.

Experiences in the use of commercial antisera for the capsular typing of klebsiella species

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Use of acetone-dried vaccines for preparing capsular antisera against the Klebsiella group and the lyophilization of Klebsiella cultures

Capsular antisera against the 72 types of Klebsiella have been prepared in rabbits by using an acetone-dried vaccine. It was shown that encapsulated cells dried with acetone and ground to a fine powder with a mortar and pestle retain their capsules. Antisera obtained from rabbits vaccinated with these vaccines had quellung titers ranging from 1:16 to 1:64. The dried vaccine was stable after storage for over 2 years at room temperature. Encapsulated cultures lyophilized in the presence of 5% sucrose, 5% sodium glutamate, and 5% polyvinylpyrrolidone remained viable and retained their capsules after storage for 10 months at room temperature.

OXYTOCA GROUP ORGANISMS ISOLATED FROM THE OROPHARYNGEAL REGION

An opinion is offered to assign "Klebsiella", which are nonmotile, indole positive, and generally gelatinolytic, to the Oxytoca group. The biochemical reactions of 19 strains of the Oxytoca group are described by methods recommended by the Enterobacteriaceae Subcommittee of the Nomenclature Committee of the International Association of Microbiological Societies for group differentiation within the Enterobacteriaceae. Fifteen of these strains were isolated from the oropharyngeal region of patients with disease.