Salmonella serotype typhimurium phage typing. A critical evaluation

Of 12,930 Salmonella serotype typhimurium strains, phage typed during 1985-1988, 45.68% were "nontypable" by Anderson's set; the percent of typable strains decreased from 54.17 in 1986 to 30.54 in 1988. Of 90 phage patterns of sensitivity, 22 were currently encountered. Phage types 1, 18 and 104 were most frequent to strain of both human and non-human origin. In food generating S. typhimurium outbreaks, phage types 1 and 36 were prevalent. Except lysotypes 198 and 95, isolated from "single cases" in man only, all other phage types were common in man and animals, too. Introducing other typing methods to serotype typhimurium "nontypable" strains (by Anderson's set) was considered necessary for epidemiological purposes.     

A survey of colicin types and phage types ofShigella sonnei in Czechoslovakia 1976–1978

In the years 1976–1978 3 552 strains ofShigella sonnei obtained from the whole Czechoslovak territory by the method of colicin typing and phage typing was examined. Each strain represented always one focus. 81.3 % of the strains were colicinogenic. Twenty-one colicin types, 41 characteristic and 105 non-characteristic phage types participated in bacillary dysentery. Of the total number, 77.4 % belonged to 9 phage types (2, 3, 6, 65, 66, 67, 75, NC IV-VIII- and NC III-IV-VIII-), which are endemic in Czechoslovakia. Of the 2 889 colicinogenic strains, 85 % belonged to 3 colicin types: 2 = Ia (31 %), 6/11 = El (27 %), 12 = E6 (27 %). Some phage types produced predominantly colicin of a certain type.     

Bacteriophage types of methicillin--resistant Staphylococcus aureus strains isolated in 2005-2006 in the Gdańsk area and their resistance to other antibiotics

The phage type of 38 methicillin--resistant Staphylococcus aureus strains isolated from clinical samples in 5 hospitals in the Gdańsk area in 2005-2007 was determined and antibiotic resistance of obtained phage types was analysed. Phage typing was performed using set of 10 phages as following: MR8, MR12, MR25, 30, 33, 38, M3, M5, 622, 56B. Drug resistance was determined by the disc--diffusion method. There were 12 phage types observed. The most frequent (28.9%) was 56B type which was present in 3 hospitals and in one hospital was found to be predominated. The studied strains were most frequent (23.7%) resistant to erythromycin, clindamycin, ciprofloxacin, trimethoprim/sulfamethoxazole, tetracycline and gentamicin. This resistance pattern predominated in strains belonging to 56B type.     

Phage types of Staphylococcus aureus strains and their antibiotic resistance in carriers of medical students population

The phage types of 78 S. aureus strains isolated from nose swabs obtained from a medical students in 2005 -2006 was determined and antibiotic resistance of the phage types was analysed. 680 students were tested in order to obtain the strains and 11.5% of them were carriers of S. aureus. Phage typing was performed using basic set of23 phages and 3 additional phages: 88, 89 and 187. Drug resistance was determined by the disc-diffusion method. The most frequent in studied population were the group III (21.8%) and strains lysed by phages belonging to varied groups (21.8%). Highly different phage patterns were observed among strains belonging to each of the group. Strains belonging to the group III as the strains lysed by phages from varied groups were most frequently resistant only to penicillin (52,9% respectively). Resistance to penicillin was also most often observed in the strains belonging to another groups and phage types. Usefulness of the additional phages 88,89 and 187 was in the investigations as no more than 51% of strains was lysed by this phages.     

Bacteriophage types of Salmonella enteritidis occurring in Poland in 1986-1995

The Lalko phages collection was used to phage type a total of 517 Salmonella Enteritidis strains isolated from food-poisoning outbreaks (312 strains) and other common sources (205 strains) in Poland, during the years 1986-1995. Above 99.0% of all strains tested were recognized as belonging to definitive phage type. Phage types 1, 6 and 7 were predominant. The strains of type 1 and 7 were most numerous. Of the 517 examined strains 312 were isolated from 46 food-poisoning outbreaks. Most of them came from the one phage type outbreaks; 8 mixed outbreaks were noted. The greatest number of the food-poisoning outbreaks was caused by Salmonella Enteritidis phage types 1, 6 and 7. Phage type 16 was isolated from persons for the first time.     

Changes in the phage typing patterns of Staphylococcus aureus strains at Concepción, Chile, in the last 30 years.

Staphylococcus aureus is a ubiquitous pathogen still implicated as a common cause of community- and hospital-acquired infections. This micro-organism has demonstrated an immense adapting capacity to rapid environmental changes. In recent years, multiresistant strains have caused increasing nosocomial infections in several parts of the world. In the period 1993-94, 455 clinical isolates were typed on the basis of traditional phage typing procedure and these data were compared with others from similar studies carried out at the Department of Microbiology, University of Concepción in 1960, 1972, and 1982. Throughout the years, phage groups have been shifting from group I to group III and examination of phage types show that types 80 and 80/81 which were the most virulent and resistant by the 1960s, had disappeared. Nowadays, types 75 and 54/75 are most frequently found, and these have been associated with methicillin-resistant S. aureus.     

Bacteriophage Typing of Salmonellae. II. New Bacteriophage Typing Scheme

A phage-typing technique for salmonellae is described. One battery of phages was used to type three serotypes of Salmonella, namely, S. typhimurium, S.typhimurium var. copenhagen, and S. heidelberg. In all, 443 S. heidelberg cultures were typed into 22 phage types, 185 S. typhimurium cultures into 35 phage type, and 92 S. typhimurium var. copenhagen cultures into 26 phage types. The stability of the phage types was established by retyping 168 cultures belonging to all three serotypes. The epidemiological significance of the phage types demonstrated was evaluated by comparing phage types obtained from the University of Minnesota and those from the National Animal Disease Laboratory. Further investigation of the S. heidelberg phage types has shown that the cultures represented repeated isolates from the same birds or from a group of birds in the same flock.     

Lysogenic phage in Salmonella enterica serovar Heidelberg (Salmonella heidelberg): Implications for organism tracing

Abstract A phage typing system using a group of 11 closely related phage (as judged by Southern analysis and restriction fragment length polymorphism analysis) was able to distinguish at least six phage types in Salmonella heidelberg of human and animal origin. Restriction fragment length polymorphism analysis using cosmid probes from S. heidelberg confirmed that most S. heidelberg isolates belong to a single 'clonal' group. Southern analysis using DNA isolated from each of the testing phage group showed that phage types 4, 5 and 6 carry closely related endogenous or lysogenic phage. Induction of a lysogenic phage Hlp-4 (Heidelberg lysogenic phage) from type 4 could become lysogenic and convert phage types 1 and 3 to phage type 4 and phage type 5 to a non-typable phenotype.     

Salmonella enterica serotype Enteritidis phage types 4, 7, 6, 8, 13a, 29 and 34: a comparative analysis of genomic fingerprints from geographically distant isolates

AIMS: To evaluate genetic heterogeneity in the most common phage types of Salmonella enterica serovar Enteritidis. METHODS AND RESULTS: A total of 233 isolates of Salm. Enteritidis from England, Northern Ireland, Spain, Hong Kong and the USA belonging to phage types (PT) 4 (n=88), PT7 (n=12), PT6 (n=72), PT8 (n=14), PT13a (n=29), PT29 (n=14) and PT34 (n=4) were characterized by PstI-SphI (PS) ribotyping and pulsed-field gel electrophoresis after digestion of DNA with XbaI. PS ribotyping differentiated the isolates into 53 different PS types and PFGE showed 14 different macrorestriction profiles; with the combination of both methods, 73 combined types were identified. Some of these clones appeared to be present within several countries. Movement of foodstuffs, animals or people may have been involved in the spread of these strains. On the other hand, some clones were only found in specific locations. CONCLUSIONS: Several well defined clonal lines seem to co-exist within the different phage types included in this study, and a combined typing approach may constitute a useful tool for epidemiological investigations. Clustering analysis of ribotypes and PFGE types agree with previous studies and suggest that phage types that share receptor binding properties can be distinguished as two families: the PT4 family including PT7 and PT6, and the PT8 family including PT13a. The other phage types are difficult to place in a family unless the geographical site of isolation is known. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper reports on an extensive assessment of the use of molecular tools for the study of the epidemiology of the enteric pathogen Salm. Enteritidis. It also gives new information regarding relationships among some common phage types.     

Development of a sequence typing scheme for differentiation of Salmonella Enteritidis strains

A DNA sequence typing scheme based on the caiC and SEN0629 loci was developed for differentiation of Salmonella Enteritidis strains and validated using a diverse collection of 102 isolates representing 38 phage types from different sources, year of isolation, geographical locations and epidemiological backgrounds. caiC encodes a probable crotonobetaine/carnitine-CoA ligase, and SEN0629 is a pseudogene. Our system allowed for discrimination of 16 sequence types (STs) among the 102 isolates analysed and intraphage type differentiation. Our findings also suggested that the stability of phage typing may be adversely affected by the occurrence of phage type conversion events. During a confirmatory phage typing analysis performed by a reference laboratory, 13 of 31 S. Enteritidis strains representing nine phage types were assigned phage types that differed from the ones originally determined by the same reference laboratory. It is possible that this phenomenon passes largely unrecognized in reference laboratories performing routine phage typing analyses. Our results demonstrate that phage typing is an unstable system displaying limited reproducibility and that the two-loci sequence typing scheme is highly discriminatory, stable, truly portable and has the potential to become the new gold standard for epidemiological typing of S .?Enteritidis strains.     

Current methods of intraspecies typing of Shigella sonnei. 3. Bacteriophage typing]

Data are presented concerning the study of the phage type of Sh. sonnei isolated in various regions of the USSR. The strains isolated belonged to 64 phage types corresponding to the Hammarstr?m's scheme. A variety of Shigella sonnei phage types both in one and in different territories of the country provided future prospects for successful use of phage typing for the purpose of epidemiological supervision and analysis of dysentery morbidity.     

Effect of photoreactivation on mutagenesis of lambda phage by ultraviolet light

There is disagreement in the literature as to whether the major mutagenic photoproduct induced in DNA by ultraviolet light is the cyclobutane dipyrimidine dimer, the most common product, or the [6-4] photoproduct, the next most frequent. In the experiments reported here, cyclobutane dimers were removed from irradiated lambda phage DNA by enzymatic photoreactivation, a process thought to affect no other photoproduct. Photoreactivation of lambda phage in host cells and of lambda DNA in solution reduced clear plaque mutants per plaque-forming unit by two-thirds, in host cells with a constant and near-maximal expression of the SOS functions required for mutagenesis. This result is interpreted to mean that removal of cyclobutane dimers in or near the mutated gene reduces mutation induced by ultraviolet light by two-thirds; therefore, cyclobutane dimers in the phage DNA are responsible for most observed mutations. DNA sequences of mutations in photoreactivated phage showed a smaller fraction of G.C to A.T transitions and a larger fraction of A.T to G.C transitions, compared to phage that were not photoreactivated. This suggests that cyclobutane dimers at TC and CC sites are particularly mutagenic.     

Genotypes of multidrug-resistant Salmonella enterica serotype typhimurium from two regions of Kenya

A combination of phage typing and pulsed-field gel electrophoresis of Xbal-digested chromosomal DNA has been used to study the epidemiological relationships of multidrug-resistant Salmonella enterica serotype typhimurium from Nairobi (64 isolates) and Kilifi (40 isolates) collected over the period 1994-1997. Isolates from Nairobi belonged to 11 definitive phage types (DTs) encompassing eight different PFGE patterns. In contrast, isolates from Kilifi were mainly DT 56 (60%) and all fell into a single PFGE pattern. The remaining isolates did not conform to a recognisable phage type. We conclude that multidrug-resistant S. typhimurium infections from Nairobi were caused by multiple strains while those from Kilifi were likely to be from a microepidemic caused by a single clone.     

Phage types and plasmid profiles of plasmid DNA strains of Salmonella enterica subsp. enterica ser. Enteritidis (S. Enteritidis) isolated from food poisoning outbreaks in 2001

Salmonella Enteritidis strains are the most often isolated Salmonella serovar in Poland. In the present study, phage typing, antibiotic resistance testing and plasmid profile analysis, have been applied to characterise 41 Polish S. Enteritidis isolates originated from human cases of salmonellosis and from other sources. The typing phages of Ward and colleagues scheme were used to type a total of 41 S. Enteritidis strains coming from Poland. All 41 strains were typable and 5 different phage types were observed. Among 41 strains tested, both PT6 and PT21 were recognized in the 15 strains (36.6%). Nine strains (22%) belonged to phage type 8. The others PTs were represented by small amount of strains (PT1var and PT4). Among all tested isolates only 4 different plasmid profiles were observed. Of the 41 strains investigated, 16 (39%) contained the 57 kb plasmid alone. The remaining 25 strains (61%) except 57 kb plasmid, possessed additional DNA particles. The probable phage type conversion of PT21 to PT1var strain, possibly connected with smaller DNA particle presence, was observed. This hypothesis needs confirmation. The real S. Enteritidis epidemiological situation in Poland should be known after introducing of systematic, annual research program.     

Staphylococcus aureus at a maternity ward. II. Characterization of isolates by enterotoxigenicity and toxic shock syndrome toxin (TSST-1) production

Tests for enterotoxins A, B, C, D, E and TSST-1 production were carried out on 775 S. aureus strains isolated from various sources (50 mothers and neonates studied periodically, mothers and infants treated for various acute inflammatory conditions, members of hospital staff, environmental swabs) during the period 1981-1983 at a maternity ward chosen for a 3-year systematic study and on additional 97 isolates obtained in 1985 from another maternity ward. This had contributed to a better classification of strains within certain phage type groups. It was found that the distribution of S. aureus types in the particular sub-sets varied, depending on the source of isolates. At the maternity ward followed for 3 years there was a clear-cut trend towards the spread of phage-untypable isolates producing enterotoxin C whereas at ward examined for comparative purposes B enterotoxin producers of phage type 95 were predominant. The tests for enterotoxigenicity has also proved to be useful as the epidemiological marker characterizing the predominantly circulating S. aureus strain. It has been confirmed that the majority role in the spread of maternity-ward-staphylococci is played by the neonates and the factors of hospital environment.     

Characteristics of PR5, a lipid-containing plasmid-dependent phage.

An extensive characterization of plasmid-dependent phage PR5 isolated from sewage has been carried out. The phage has a head diameter of 65--68 nm, is isometric with a double-layered capsid, and a minority possess tails. It adsorbs to many but not all types of bacteria possessing P, N, or W plasmids. The phage contains 20% lipid, 15.1% DNA, and 64.9% protein by weight and has a buoyant density of 1.265 g/ml in CsCl. The DNA is double-stranded with a G + C content of 49% and a molecular weight of 7.4 +/- 0.6 x 10 (6) as shown by electron microscopy. Phospholipid content is 66% of lipid and consists of cardiolipin (13%), phosphatidylethanolamine (43%), and phosphatidylglycerol (44%) and differ quantitatively from that of host bacteria. Anti-PR5 serum inactivates other similar phages, PR3 and PR4. Phage adsorption is impaired in deep rough mutants of Salmonella minnesota.     

Genome of a virulent bacteriophage Lb338-1 that lyses the probiotic Lactobacillus paracasei cheese strain

There is a lack of fundamental knowledge about the influence of bacteriophage on probiotic bacteria and other commensals in the gut. Here, we present the isolation and morphological and genetic characterization of a virulent narrow-host-range bacteriophage, φLb338-1. This phage was isolated from fresh sewage and was shown to infect the probiotic cheese strain Lactobacillus paracasei NFBC 338. Electron microscopy studies revealed that φLb338-1 is a member of the Myoviridae family, with an isometric head, a medium-sized contractile tail, and a complex base plate. Genome sequencing revealed a 142-kb genome with 199 open reading frames. Putative functions could be assigned to 22% of the open reading frames; these had significant homology to genes found in the broad-host-range SPO1-like group of phages which includes the Enterococcus faecalis phage φEF24C, Listeria phage A511, and Lactobacillus plantarum phage LP65. Interestingly, no significant genomic similarity was observed between the phage and the probiotic host strain. Future studies will determine if the presence of bacteriophage φLb338-1 or others in the human or animal gut plays an antagonistic role against the probiotic effect of beneficial bacteria.     

Epidemiological studies on aging in France: from the PAQUID study to the Three-City study

Follow-up of cohorts recruited in general population with active screening and diagnosis of incident cases, is the most appropriate epidemiological design for studying incidence and risk factors of Alzheimer disease and other types of dementia. In France, people considered in the PAQUID study, then in the EVA study, have been the first cohorts on dementia. They have prepared the way for the Three-City (3C) study, conducted in Bordeaux, Dijon and Montpellier. About 9500 persons aged 65 years and over have been recruited in these three cities and will be followed-up during four years. The main objective of the 3C study is to investigate the relation between vascular risk and neurodegenerative diseases. The 3C study will provide essential data for defining strategies for dementia prevention. To measure the impact of the strategies on the incidence of dementia and the social burden of this disease will be an important public health objective in the near future.     

Use of WARD et al's scheme for bacteriophage typing of Salmonella enteritidis strains isolated in Poland

The typing phages set of Ward et al. was used to type a total of 517 strains of Salmonella Enteritidis isolated in Poland in 1986-1995. According to the Ward et al. scheme, 56.5% of the strains tested were assigned to 14 different phage types. Phage types 8, 4, 1 and 4a were placed first, second, third and fourth, respectively. They were dominated both in the outbreak isolates and in the isolates from the other sources. Ten phage types were represented by single strains. Other strains reacted with phages without showing any of the designated phage type (37.1%) or were untypable (6.4%). The Ward et al. scheme seems to demonstrate not enough high degree of strain discrimination for Salmonella Enteritidis isolates in Poland. It seems that the Ward et al. scheme is not enough useful for the epidemiological investigations of Salmonella Enteritidis in Poland.