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PubMed1981

Comparison of epidemiological methods for differentiation of Proteus mirabilis.

During the study of suspected cross-infection within a hospital, epidemiological typing techniques are often employed to aid in the identification of transmission patterns of nosocomially-acquired bacteria. In this study, five bacteriological typing methods were assessed for their ability to type and differentiate 100 clinical isolates of Proteus mirabilis. The methods evaluated include biotyping, bacteriophage typing with the method of Hickman and Farmer and the scheme of Schmidt and Jeffries, and typing by both bacteriocin production and bacteriocin sensitivity. Each of the phage and bacteriocin methods were further evaluated by typing 14 isolates of P mirabilis derived from an outbreak of infection on a surgical intensive care unit. All 100 isolates were typed by biochemical characteristics and were divided into seven distinct biotypes. Ninety-five percent of these strains were separated into 61 lysis patterns with the phage set of Hickman and Farmer whereas the Schmidt and Jeffries phage scheme was able to type 67% of the cultures into nine unique lysis patterns. Bacteriocin sensitivity typing resulted in 41 distinct patterns with 71% of the strains typable and typing by bacteriocin production yielded 29 distinct bacteriocin types among the 80% typable strains. Typing by bacteriocin production demonstrated that 13 of the 14 epidemic isolates were the same strain. All epidemic-related cultures were untypable with the Hickman and Farmer phage set, whereas typing by bacteriocin sensitivity and the phage set of Schmidt and Jeffries resulted in two and four isolates typable, respectively. Based on the results of typing random and epidemic isolates of P mirabilis, bacteriocin production typing is recommended as a sensitive and specific typing method for future epidemiological surveys.

Bacteriological Techniques↗
PubMed1999

The incorporation of a non-natural amino acid (aza-tryptophan) may help to crystallize a protein and to solve its crystal structure. Application to bacteriophage lambda lysozyme.

Until now, wild-type bacteriophage lambda lysozyme had been impossible to crystallize. This difficulty could be overcome by the replacement of the four tryptophan residues by aza-tryptophans. Analysis of the intermolecular and intramolecular contacts in this modification allows understanding of the differences in behaviour between the native and modified molecules. Furthermore, this mutation was very useful for the creation of new heavy-atom binding sites and for the solution of the non-crystallographic symmetry, which is extremely important for phase improvement. This procedure seems to be generally applicable, at least in the search for new possibilities for heavy-atom binding sites.

Aza Compounds↗
PubMed2002

Temperate phages in Salmonella enterica serovar Typhimurium: implications for epidemiology.

Salmonella enterica serovar Typhimurium is the most common Salmonella serovar isolated from humans in Australia. The most common definitive phage types (DT) include 9, 64 and 135. Induction of lysogenic phages from DT 64 with mitomycin C followed by cesium chloride gradient purification, resulted in separation of two populations of phage particles. DNA extracted from these particles that was digested with SmaI showed two distinct patterns of banding. Transmission electron microscopy showed that both phage particles belong to the podovirus family of the C1 morphotype. One of the phages, ST64T is capable of mediating both generalized transduction and bacteriophage type conversion. Crude phage lysate induced from S. Typhimurium DT 64 was capable of phage type conversion. S. Typhimurium DT 9 was converted to DT 64 and DT 135 was converted to DT 16. S. Typhimurium DT 41 was also converted to DT 29. Amplified-fragment length polymorphism revealed differences between the original isolates and the convertants. Phage type conversion raises the question of the stability of the bacterial phage types in natural settings and the possibility of its occurrence during an outbreak scenario.

Animals↗
PubMed1982

Characterization of resistance plasmids and carried phages in an epidemic clone of multi-resistant Salmonella typhimurium in India.

Hospital outbreaks of severe gastroenteritis caused by multi-resistant Salmonella typhimurium have occurred in a number of cities throughout India since 1977. The strains involved belong to phage types 66 or 122, or are untypable; the latter are derived from types 66 or 122 by acquisition of one or more of a number of temperate bacteriophages. Types 66 and 122 are closely related and react with the same phages of the S. typhimurium typing scheme. A plasmid belonging to compatibility group F1me encoding resistance to ampicillin, chloramphenicol, kanamycin, streptomycin, sulphonamides, spectinomycin, tetracyclines, gentamicin and trimethoprim (R-type ACKSSuSpTGTm) is present in all of the multi-resistant strains. Several other plasmids have been identified including an SSu resistance determinant, a group I2 transfer factor and an R factor coding for resistance to kanamycin, streptomycin and sulphonamides which is compatible with plasmids of all the standard compatibility groups. These plasmids are only present in a proportion of the strains examined. Examination of strains from other sources has identified a paediatric hospital outbreak in Saudi Arabia and a number of sporadic infections in Great Britain which have been caused by the same organisms. These studies show that, despite differences in phage type and plasmid content, this group of strains belongs to a single clone which has become widespread in India with some extension to other countries.

Bacteriophage Typing↗
PubMed1999

Predominant phage types of coagulase positive staphylococci in hospital infections.

360 strains of Staphylococcus aureus isolated from various clinical specimens were subjected to bacteriophage typing. 247(68.6%) strains were typable. Among the typable strains 75(20.83%) belonged to phage group I, 45(12.5%) belonged to phage group III, 6(1.67%) belonged to phage group II and 14(3.89%) strains belonged to miscellaneous group. By far, the largest was the mixed group having 107(29.72%) strains. 113 strains (31.4%) were untypable. All the strains were tested for antibiotic sensitivity test. 287 (79.7%) were multiple drug resistant strains.

Bacteriophage Typing↗
PubMedDate not supplied

Phage-typing system for Salmonella hadar of animal origin.

A phage-typing system for Salmonella hadar was developed. Fifteen phages isolated from untreated sewage were used to phage-type 55 isolates of S. hadar recovered from avian and other animal species. Twenty-four distinct phage types of S. hadar were established based on lysis patterns. Methods involved in the isolation for bacteriophages for a particular serotype and the importance of bacteriophage typing is discussed in the context of the importance of S. hadar.

Animals↗
PubMed1978

Bacteriophage specificity in the identification of Yersinia pestis as compared with other enterobacteria.

Bacteriophage typing of Yersinia pestis and the specificity of the phage among Enterobacteriaceae were investigated. The bacteriophage used for rapid identification of Y. pestis reacted with representative strains of all recognized species of Shigella as well as with Salmonella cholerae-suis. Reactive Shigella serotypes were Sh. dysenteriae 1 and 9, Sh. flexneri 2a, Sh. boydii 1 and 6, and Sh. sonnei. Patterns consisting of isolated plaques (two cases) or absence of plaques were observed when the routine test dilution (RTD) of the phage was used. Results were independent of the incubation temperature (20, 28 or 37 degrees C). Representative strains of Escherichia, Proteus, Providencia and Klebsiella were resistant to the bacteriophage even at 1000 X the RTD established for Y. pestis.

Bacteriophage Typing↗
PubMed1976

[Typing of Shigella sonnei in the GDR during epidemiological surveillance].

A total of 35,503 strains of Sh. sonnei were typed during the period from 1962 to 1974 at the Institute of Experimental Epidemiology. The principal method used was bacteriophage typing, and biochemical typing and determination of colicine formation served as auxiliary methods. Colicine type, resistogram and in some cases R-factor were determined in some of the strains. Such complex typing of Sh. sonnei is of value in epidemiological practice.

Bacteriocins↗
PubMed1986

[Evaluation of the possibility of using genetic and microbiological research methods for resolving current problems in the epidemiology of salmonellosis].

S. typhimurium strains isolated in 14 regions of the USSR have, parallel with considerable similarity in their biological characteristics, a number of essential differences. These differences become manifest in the determination of the plasmid spectra of the above organisms. The transfer of R-plasmid PLE518 F1 me fin+ with a molecular weight of 96 Md to strains, sensitive to the action of typing bacteriophages, renders these strains resistant to the lytic action of a number of phages, which leads to the conversion of their phage type. In some cases it may deteriorate the validity of the method of phage typing, used for epidemiological purposes.

Anti-Bacterial Agents↗
PubMed1983

[Oxacillin and gentamicin-resistant Staphylococcus aureus: surveillance and development over a period of 6 months].

An outbreak of nosocomial infections caused by oxacillin and gentamicin-resistant Staphylococcus aureus occurred over a 3 month period in the intensive care unit of a 371-bed hospital. Four patients were infected. S. aureus isolates were resistant to multiple antibiotics beside oxacillin and gentamicin. They exhibited identical antibiotic susceptibility pattern and identical phage type (47/54/75/77/84/85). A subsequent survey of oxacillin-resistant S. aureus was conducted in the hospital during a 6 month period. Bacteriophage typing was performed on 52 isolates of oxacillin-resistant S. aureus. Seventeen were non typeable . Fourteen had the same phage type (or a minor variant +/- 2 numbers) as that of the previously isolated S. aureus. The antibiotic susceptibility pattern of 10 of the 14 isolates was identical to that of the epidemic strain. The antibiotic susceptibility patterns of 2 isolates differed from it with respect to the resistance to one antibiotic among those tested (these two isolates were obtained from patients that received the particular antibiotic before the isolation of the Staphylococcus). The 7 patients from whom these 12 S. aureus were isolated were staying in the intensive care unit except one who was hospitalized in this unit several months ago. Among the personnel screened, two intensive care unit nurses were found to be nasal carriers of oxacillin resistant S. aureus. One strain had the same phage type as that of the epidemic strain but its antibiotic susceptibility pattern was different. Room-mate to room-mate spread within the intensive care unit may be responsible for the perpetuation of the epidemic strain.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage Typing↗
PubMed2004

Endemic, epidemic clone of Salmonella enterica serovar typhi harboring a single multidrug-resistant plasmid in Vietnam between 1995 and 2002.

Salmonella enterica serovar Typhi strains resistant to ampicillin, chloramphenicol, tetracyclines, streptomycin, and cotrimoxazole, isolated from sporadic cases and minor outbreaks in Vietnam between 1995 and 2002, were typed and compared. Plasmid fingerprinting, Vi bacteriophage typing, XbaI pulsed-field gel electrophoresis, and PstI ribotyping showed that endemic, epidemic multidrug-resistant typhoid fever was due, for at least 74.1% of the isolates, to one or two clones of serovar Typhi harboring a single resistance plasmid. PstI ribotyping was used as a basic technique to ensure that a serovar Typhi expansion was clonal.

Conjugation, Genetic↗
PubMed1979

A code for reporting and comparing results in phage typing.

This code, like the others proposed, involves the definition of a characteristic reaction for each system. Each reaction must be positive or negative. As regards the interpretation of results, it is worth noting that if the bacteriophage typing system uses not less than 5 phages, there is no problem for interpreting the results of small series of 10 to 20 strains, whatever the code used. But should the system use more than 5 phages, the advantage offered by the octal code becomes obvious because, without computer, the manual coding for comparing the results of various series is always possible. Beyond 6 phages, the binary pattern reporting, unintelligible without correction, is possible with an octal number not exceeding 7 digits for a pattern corresponding to a 21-phage set. When very large series of strains are considered, the coding can be completely done and printed out by any computer through a very simple program. This proposed code is not only rational but also a useful method even if the number of phages used is larger than 20 or 30, but after a computer becomes necessary however the coding system used.

Bacteriophage Typing↗
PubMed1984

Characters of coagulase-negative staphylococci and micrococci from cases of endocarditis.

Strains of coagulase-negative staphylococci and micrococci submitted to a reference laboratory from 137 cases of endocarditis over a 5 year period were reviewed. Staphylococcus epidermidis biotype 1 (SII) was the commonest biotype in all groups of patients but exceeded 80 per cent in the 61 patients who had undergone prosthetic valve surgery and the 16 patients who had undergone other forms of surgery. Biotype 4 (SVI) was recovered from 10 of the 34 patients without surgery. Strains from prosthetic valve endocarditis were frequently resistant to many antibiotics while strains from natural valve endocarditis were frequently sensitive to all, or resistant only to penicillin. The value of bacteriophage typing was confirmed.

Adult↗
PubMed1998

Polymorphism of Listeria monocytogenes and Listeria innocua strains isolated from short-ripened cheeses.

Thirty isolates of Listeria monocytogenes and 18 of L. innocua obtained from different short-ripened cheeses manufactured in Asturias (northern Spain), were compared with each other and with reference strains using serotype, phage type and pulsed-field restriction endonuclease digestion profiles analysis of the total DNA. Restriction enzymes ApaI and SmaI defined five clusters in L. monocytogenes (m1 to m5) and two main clusters in L. innocua (i1 and i2). Cluster i2 was further arranged into three subclusters (i2a, i2b and i2c) based on the different Eco52I (XmaIII) and Crf42I (SacII) patterns of its isolates. Clusters of L. innocua were clearly different whereas those of L. monocytogenes were more closely related to each other. In this latter species, serotype 4b isolates (m4 and m5) constituted a more homogeneous group than serogroup I isolates (m1, m2 and m3). Cluster m3 contained two strains of serotype 1/2a whereas m1 and m2 harboured strains of both serotypes, 1/2a and 1/2b. Therefore, the combined use of restriction patterns and serotype may be useful to differentiate L. monocytogenes strains showing identical restriction profiles but differing in serotype. The cheese source of Listeria strains proved that isolates from cluster m1 were repeatedly detected as a contaminant in the same type of cheese. Comparison of L. monocytogenes ApaI profiles showed a genetic proximity of m4 and m5 to the recognized pathogenic strains ATCC 13932 and NCTC 11994, responsible for meningitis cases in other countries. Finally, bacteriophage typing data indicated that m4, the sole phage typable group, had a phage type resembling that of strains causing the Auckland (New Zealand) outbreak of listeriosis in 1969. These data suggest a wide distribution of closely related types which might cause, under several circumstances, sporadic cases of listeriosis.

Bacteriophage Typing↗