Bacteriocin Typing Research Articles

The epidemiological type identification of Serratia marcescens from outbreaks of infection in hospitals.

A study of serological, bacteriocine and phage typing of Serratia marcescens was made. Specific O-antisera of adequate titre were relatively simple to prepare but H-antisera exhibited many heterologous agglutination reactions amongst the type strains. Most of these cross-reactions were not reproduced when immobilization tests with H-sera were performed. Direct haemagglutination tests were used to establish the presence of fimbriae amongst the H-type strains and the results of agglutination tests with non-fimbriate variants of strains indicated that fimbrial antibody in high titre was present in some sera. Replicate typing of 100 pairs of cultures by the phage-typing method indicated that small variations in pattern were common and that larger variations occurred occasionally. Therefore differences in pattern of less than two strong reactions should not be taken as evidence that strains can be distinguished. Cultures of S. marcescens, 273 in total, from six outbreaks of infection in British and European hospitals were typed by O-serology, H agglutination and immobilization tests, phage typing and bacteriocine susceptibility by a cross-streaking method. The typability of strains by each method was high but the results suggested that no single method was sufficiently discriminating to be used alone for typing. Comparison of the H-type and typing patterns of members of the same O serogroup from incidents of infection showed that reliable results were obtained by H-typing or by phage and bacteriocine typing after the application of the appropriate 'difference' rule. The greatest discrimination between strains of the same O-group was obtained by the use of H-typing or phage typing.

Klebsiella species in hospital food and kitchens: a source of organisms in the bowel of patients.

Hospital food was examined for the presence of Klebsiella species. Salads and cold meat were most frequently contaminated, often containing more than 10(3) organisms per g. Klebsiella species were also widely distributed in the kitchen environment which was considered, at least in part, to be the source of the organisms in food. By the use of serological and bacteriocin typing, intestinal carriage of strains ingested in food could be demonstrated.

Serotyping of Serratia marcescens: current status of seven recently described flagellar (H) antigens

The slightly revised, current scheme of 20 flagellar (H) antigens of Serratia marcesens was examined. The seven new H antigens were demonstrated to be antigenically distinct as determined with Le Minor's H-immobilization test. The H-immobilization antibodies of rabbit anti-H immune sera proved resistant to treatment with 2-mercaptoethanol and dithiothreitol, respectively. On the other hand, dual absorptions of rabbit anti-H immune sera with killed cells of Staphylococcus aureus strain Cowan I, i.e., protein A, failed to reduce significantly H-immobilization titers of rabbit sera, although human immunoglobulins G and M were bound by protein A. It was tentatively concluded that the 2-mercaptoethanol- and dithiothreitol-refractory H-immobilizing rabbit antibodies belonged to the immunoglublin M class. H-antigen (phase) variation was not demonstrable in several extramural, clinical isolates of S. marcescens for which this phenomenon had been claimed. Rather, four of these six isolates were found to consist of cell populations of two distinct serotypes, as also borne out by bacteriocin typing; the flagellar H-antigens of the remaining two isolates were stable, with minor, hterologous H-antigen cross-reactivity.

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.

The development and assessment of a bacteriocin typing method forKlebsiella

Klebsiellas are generally typed by the method of capsular serotyping but, although this is a reliable method, it is time consuming, requires the production of a large number of antisera and is not generally available. For this reason another method for typing klebsiellas was sought. A bacteriocin typing method involving mitomycin C induction was developed and the cultural conditions giving optimum klebecin production and the best methods of testing the sensitivity of the organisms to klebecins were determined. Of 190 klebsiella strains screened for bacteriocinogeny, only 68 (35.8%) produced klebecin and after calculation of similarity values by computer analysis, a typing set of 15 producers was selected. This typing set allowed over 96% of klebsiella strains to be typed and tests of the reproducibility of the method and the variability of typing patterns in natural populations of klebsiella indicated that results of acceptable accuracy could be obtained, while retaining good discrimination if two or more differences were required between patterns before they were regarded as distinct. A complete set of capsular antisera were prepared, enabling the results obtained from klebecin typing to be compared with those from serotyping. There was generally close agreement between the results from the two typing methods and greater discrimination was obtained between similar strains when the two methods were combined. Klebecin typing and serotyping revealed relationships between strains from five outbreaks of infection, and strains of the same serotype from different hospitals could frequently be distinguished by their klebecin typing patterns.

Suggested procedure allowing use of plastic petri dishes in bacteriocin typing

After bacteria are mechanically removed from solid media, the remaining viable cells can be killed by exposure to chloroform vapors. Until recently, the applicability of this procedure was restricted to glass petri dishes. Here a procedure is described in which plastic petri dishes are used and remain stable in the presence of chloroform vapors.

Bacteriocin typing of Clostridium perfringens in human feces

Three hundred and ninety-nine isolates of Clostridium perfringens from enriched stool specimens of 51 individuals (about eight colonies per person) were typed by bacteriocins. Forty-nine percent of these persons carried more than one bacteriocin type in their stool, and some had three or four different stains as determined by bacteriocin typing. Weekly stool specimens obtained from seven positive volunteers over a period of 5 weeks were screened for C. perfringens, and several colonies from each person were typed. This survey demonstrated that the number of types fluctuated with time, several types could be carried simultaneously, and the isolation of the organism was variable. Nine new bacteriocin types of C. perfringens were isolated in this study.

Evaluation and application of an improved bacteriocin typing method for Klebsiella aerogenes.

A bacteriocin typing method was evaluated using 200 strains of Klebsiella aerogenes, 93% of which fell into 11 distinct types. The typing technique was successfully applied to the monitoring and control of hospital cross-infection.

Der Hospitalismus aus bakteriologischer Sicht

In spite of the successful treatment of bacteriological infections combined with progress in hospital hygiene there remain still problems of infective hospitalism in certain sections of the hospital. Generally, the causative bacteria are nosoparasites not being dangerous to human beings in good condition. From this point of view Pseudomonas aeruginosa and Serratia marcescens are the most important species. A successful challenge against infective hospitalism is only possible under the supervision of the bacteriologist. It is his task to isolate and differentiate the bacteria and to carry out the sensitivity tests against antibiotics. Besides this, he has to treat epidemiological and hygienic problems. Special kinds of methods sometimes have to be used to find out the sources and the routes of spreading of the infections in a hospital e.g. bacteriophage typing, bacteriocin typing and analysis of the antigenic structure. Likewise, the transmission of bacteria by air has to be studied and continuous controlling measures and monitoring are required. The bacteriologist is also responsible for preparing hygiene instructions. There always has to exist a good cooperation between the bacteriologist, the clinical doctors, the nurses and the technical staff. The whole problem can only be handled by special teams.

A comparison of typing methods forSerratia marcescens

A simple method for the bacteriocine typing of Serratia marcescens without the use of induction was sought. The results of a mutual inhibition experiment with 89 unrelated cultures indicated that a bacteriocine-susceptibility method would give more discrimination between strains than would a bacteriocine-production method. A cross-streaking technique for bacteriocine-susceptibility typing without previous induction was developed, and its performance was compared with that of another susceptibility-typing method in which cell-free lysates of the producer strains were obtained by induction with mitomycin C.Replicate typing of the same collection of cultures by both methods indicated that small variations in pattern were common and that larger variations occurred occasionally. Differences in pattern of less than two strong reactions in the mitomycin-C induction method, and of less than three strong reactions in the cross-streaking method, should therefore not be taken as evidence that strains can be distinguished.Sets of cultures of Ser. marcescens, 178 in total, from a number of supposed incidents of infection in hospitals, were used to evaluate the two bacteriocine-typing methods; all of the cultures were also O serogrouped. Comparison of the typing patterns of members of the same O serogroup from clear-cut incidents of infection confirmed that results of acceptable reliability could be obtained by either bacteriocine-typing method by the application of the appropriate ;difference' rule. When so interpreted, the cross-streaking method appeared to be slightly the more discriminatory.The greatest discrimination between strains was obtained by the use of a ;hierarchical' typing system in which the strains were first O serogrouped, and the cross-streaking method of bacteriocine typing was then used to make subdivisions within O serogroups.

SERRATIA: OPPORTUNISTIC PATHOGEN OF INCREASING CLINICAL IMPORTANCE

Serratia marcescens can become a formidable nosocomial (hospital acquired) pathogen, and is reported increasingly in the world literature. However, it is only a recently recognized problem in Australia. Serratia can carry an antibiotic-resistance plasmid, and, after entry of the organism into very sick patients, it may be hard or impossible to eliminate. Initial experience of Serratia in 34 consecutive cases isolated in a three-months period is presented. Rapid increase in the number of Serratia infections occurred after the appearance of a resistant strain. Urinary infection was the commonest presentation (91% of cases). The presence of an indwelling urinary catheter in a debilitated patient was the major predisposing factor. Significant bacteraemia followed in four cases with one death. Contamination of burns (surfaces) and surgical wounds was found in four cases. Serratia strains were found to be highly resistant to most antimicrobial agents in routine sensitivity testing, 20% being fully resistant to all tested agents, and nalidixic acid being the most effective inhibitor in the remainder. With bacteriocin typing of Serratia, two types were found to be dominant. These two bacteriocin types were not identified among strains isolated from other sources such as soil, water and local hospitals. Pharyngeal carriage was found in only one case, but faecal excretion of Serratia was found in 11 cases and may be a significant portal of dissemination. Cross-infection from a hospital reservoir of resistant organisms is postulated. A model of cross-infection is also proposed, and methods of control are discussed. In view of the established danger of Serratia in the hospital setting, its isolation can no longer be ignored.

Bacteriocin typing of streptococcal isolates from endocarditis.

A typing system based on bacteriocin production and sensitivity for Streptococcus sanguis strains was devised. Bacteriocin producer strains were grown (37degrees C) anaerobically on brain heart infusion-yeast extract agar for 18 h. Bacteriocin indicator strains were suspended to molten brain heart infusion-yeast extract agar and then overlayed onto the producer strain. After an additional 18 to 24 h of incubation, zones of bacteriocin inhibition were recorded. After establishment of the typing system, eight Streptococcus strains from bacterial endocarditis patients were characterized by the typing system. Four patient strains had identical bacteriocin reduction patterns but could be differentiated by differences in their bacteriocin sensitivity. Two isolates from the same patient had identical production and sensitivity patterns. By including both bacteriocin production and bacteriocin sensitivity, all seven epidemiologically unrelated isolates could be differentiated. On the basis of these results, there does not appear to be a correlation between bacteriocin production and infectivity, but the usefulness of the application of a typing system to a clinical situation is demonstrated.

Bacteriocin typing by leakage of ultraviolet light-absorbing material

A rapid and reproducible method of bacteriocin typing is described based on leakage of ultraviolet light-absorbing material (UVAM), detectable in supernatants of bacteriocin-sensitive cultures, by means of a spectrophotometer. The prerequisites for reproducible results, with nonsignificant fluctuations in standard error of the mean, are: a set of standardized bacteriocins, produced under defined conditions and of determined strength. These must interact with the unknown bacterial culture in suspension and at a given ratio in order to achieve an optimal multiplicity of interaction. Pyocin and colicin typing by the "scrape and streak" technique of Gillies (J. Hyg. 62:1-10, 1963) was compared with the UVAM leakage method in 275 tests; the two tests were found to be in good agreement for the strains tested.

Evidence for the transmissibility of human dental caries

Strains of Streptococcus mutans, an organism strongly implicated in the aetiology of human dental caries, have been identified by means of a bacteriocin typing technique. Examination of family groups suggests that the organism can be transmitted intrafamiliarly thus supporting the notion that human dental caries is an infectious transmissible disease.

Typing of Proteus Strains by Proticine Production and Sensitivity

A simple, reliable and highly discriminating scheme for the bacteriocine typing of Proteus has been developed. Strains are typed on MacConkey's agar according to their ability to produce a proticine active against one of 14 indicator strains having a single and specific proticine sensitivity and also according to their sensitivity to the different proticines of 13 proticine-producing strains. This new scheme of combined production and sensitivity typing was formulated after 250 strains of Proteus from clinical material had been examined for the production of proticines active against the 24 indicator strains of Cradock-Watson's proticine typing scheme and for proticine activity and sensitivity towards each other. Three new types of proticinogenic strains were discovered and defined. Strains producing proticines of types 1, 2 and 3 were isolated frequently. These common proticines could be subtyped by their different actions on newly characterised indicator strains. By means of this production/sensitivity (P/S) typing scheme, 250 Proteus strains were differentiated into 90 distinct types, whereas typing by sensitivity alone distinguished only 40 types and typing by production alone distinguished only 20 types (including subtypes).

The Urometer as a Reservoir of Infectious Organisms

With the aid of epidemiologic tools such as serotyping and bacteriocin typing, organisms involved in hospital-acquired infections were traced to their hospital reservoir. One of these reservoirs was an instrument used to measure specific gravity of urine, the urometer.

Bacteriocin patterns of strains belonging to various serotypes of Streptococcus mutans

A number of well-documented strains representative of the various serotypes of Streptococcus mutans were characterized by their ability to produce bacteriocin(s) against 14 selected indicator strains and by their sensitivity to 11 bacteriocinogenic strains of Strep. mutans. This method of characterizing the strains indicated, in agreement with previous suggestions, that strains belonging to serotypes a and b form readily recognizable sub-groups of Strep. mutans. Strains of the recently described serotype g also appeared to comprise a well-defined group but this was not so in the case of the serotypes c, d, e and f. It was concluded that the division of Strep. mutans into sub-species is unwarranted at the present time and that for epidemiological studies, methods such as bacteriocin typing may be of greater value.

Bacteriocinogeny and the properties of some bacteriocins of streptococcus mutans

Of 143 strains of Streptococcus mutans investigated, 98 (70 per cent) were bacteriocinogenic on one or more of a series of indicator strains. The bacteriocins were active not only against other streptococcal species such as Strep. pyogenes, Strep. pneumoniae and enterococci but also against a number of unrelated Gram-positive bacteria. However, the two Gram-negative strains tested were not attacked. Many strains appeared to produce more than one type of bacteriocin and the diversity among these types was evidenced by differences in host-range patterns, sensitivity to heat, chloroform and proteolytic enzymes and, ability to diffuse through membranes. It was clear, however, from an assessment of these characteristics that bacteriocins of both the low and high molecular weight types were produced by various strains of Strep. mutans. On a world-wide basis, strains of serological type c are common and certainly predominate among local isolates. The high incidence of bacteriocinogeny among strains of this serotype, coupled with the fact that most other strains either produced or were sensitive to Strep. mutans bacteriocins, indicated that a bacteriocin typing scheme might be valuable as an epidemiological tool.

Bacteriocin typing of Pseudomonas putrefaciens from food, human clinical specimens, and other sources.

With the use of 4 bacteriocin donor strains of Pseudomonas putrefaciens most low G+C strins were readily distinguished from high G+C strains. Two bacteriocin donor strains exhibited autoinhibition when subjected to bacteriocin typing.

Characteristics of weak H2S-producing isolates of Pseudomonas putrefaciens from human infections.

Isolates from human clinical specimens which produced salmon-colored colonies were found to grow at 2C and produce ornthine decarboxylase, DNase, trimethylamine and only slight amounts of H2S. The notably weak ability of such isolates to produce H2S was originally regarded as a negative reaction. The DNA base composition of such isolates was found to range from 48.3 to 49.2 moles % GC. These observations, along with bacteriocin typing, resulted in identification of the isolates as Pseudomonas putrefaciens.