Computer analysis of Staphylococcus aureus phage typing data from 1957 to 1975, citing epidemiological trends and natural evolution within the phage typing system

Computer analysis of Staphylococcus aureus phage ty ping data collected for over 18 years in a large research hospital showed a drastic decrease in the number of hospital epidemic strains. Phage lysis patterns gradually modified from those of earlier years and were a reflection of changes within the S. aureus reservoir, and not within the typing phages, since the typing phages were used from stable lyophilized stocks. There was increasing cross-lysis of S. aureus strains by phages of lytic groups I, II, and III, such that this grouping was no longer epidemiologically valid. A 61% increase in unique strains occurred from the period 1957 to 1975. Disappearance of the widely recognized epidemic strains was followed by a proliferation of unique strains with individual phage patterns. These increased from 38% in the period 1957 to 1962 to 62% in the period 1969 to 1975, indicating a trend toward a "one patient-one strain" situation. Nontypable strains decreased in more recent years from 16% (1957 to 1975) to 7% in 1978, following introduction of phages 94, 96, 292, and D-11. Pandemic S. aureus strain 80/81 first appeared in this hospital in 1959, 5 years after it was first reported in the United States. Strain 80/81 disappeared from the hospital in 1963, partly due to the advent of methicillin.     

Computer analysis of Staphylococcus aureus phage typing data from 1957 to 1975, citing epidemiological trends and natural evolution within the phage typing system.

Computer analysis of Staphylococcus aureus phage ty ping data collected for over 18 years in a large research hospital showed a drastic decrease in the number of hospital epidemic strains. Phage lysis patterns gradually modified from those of earlier years and were a reflection of changes within the S. aureus reservoir, and not within the typing phages, since the typing phages were used from stable lyophilized stocks. There was increasing cross-lysis of S. aureus strains by phages of lytic groups I, II, and III, such that this grouping was no longer epidemiologically valid. A 61% increase in unique strains occurred from the period 1957 to 1975. Disappearance of the widely recognized epidemic strains was followed by a proliferation of unique strains with individual phage patterns. These increased from 38% in the period 1957 to 1962 to 62% in the period 1969 to 1975, indicating a trend toward a "one patient-one strain" situation. Nontypable strains decreased in more recent years from 16% (1957 to 1975) to 7% in 1978, following introduction of phages 94, 96, 292, and D-11. Pandemic S. aureus strain 80/81 first appeared in this hospital in 1959, 5 years after it was first reported in the United States. Strain 80/81 disappeared from the hospital in 1963, partly due to the advent of methicillin.     

Evaluation of the usefulness of three collections of bacteriophages for typing methicillin-resistant Staphylococcus aureus,isolated in Moscow hospitals

The typing of S. aureus methicillin-resistant strains, isolated in different hospitals of Moscow; was carried out with the use of three collections of phages: the International Set of Phages; the set of phages of the International Center of S. aureus phage typing in London (L); and the experimental collection of phages of the Gamaleya Institute of Epidemiology and Microbiology in Moscow (M). In this study made with the use of both the phages of the International Diagnostic Set and phages L in the standard typing dose of 1 TP about 6% of the cultures under study proved to be sensitive. When the typing dose was increased to 100 TP the phages of the international diagnostic set lyzed 75.5% of the cultures. The typed strains were found to belong to phage types 77 (71.7%), 77/84/85 (19.6%) and 94/96 (6.5%). At a concentration of 100 TP phages L lyzed 83.7% of the cultures, but the dominating phage types could not be determined due to a great variety of phage markers. In contrast to the two preceding collections, the third phage collection M was composed in such a way that in the study of the investigated culture the specificity of its restriction modification was primarily evaluated and only then the presence of antiphage immunity was determined. This latter collection was used in the evaluation of 93.1% of the cultures. By the specificity of their restriction specification system the majority of them were classified with two new groups, heretofore not described. Only this collection M made it possible to differentiate epidemic and sporadic strains and to evaluate the epidemic situation in all 6 hospitals.     

Changes in the Phage-Typing Patterns of Staphylococci Following Lysogenization

The phage typing patterns of phage type 52/52A/80/81 staphylococcal strains were changed to type 80/81 and the non-typable group by lysogenization with phages 27 and 146. When a particular strain of Staphylococcus aureus, MS1590 phage type 52/52A/80/81, was lysogenized with phage 146, type 80/81 and the non-typable group strains were produced. According to the comparison of host range of the prophages, it has been concluded that the two strains with different phage typing patterns have different kinds of prophages.     

Evaluation of the usefulness of new international experimental phages for typing methicillin resistant Staphylococcus aureus (MRSA)

The aim of the study was to determine the usefulness of the set of experimental phages obtained from the Central Public Health Laboratory in London for typing of MRSA strains in Poland. The study was performed on 150 MRSA strains isolated from various clinical materials in various regions of the country. The set of 10 experimental phages and the international basic set of 23 phages were used for typing. The results of the study showed that 76.8% of MRSA strains were typing with the experimental set of phages. The frequency of inhibition reactions was 19.9%. Only 3.3% of the strains were nontypable with the new phages while nearly half of the studied strains were nontypable with the basic set of phages. The studied strains were divided into 19 phagotypes. There was a high frequency of typable strains among MRSA typable and nontypable strains and those inhibited by the basic set of phages (71.4%-85.7%). These data indicate that the set of 10 experimental phages is useful for typing of MRSA strains isolated in Poland except for phage M3 which failed to react with almost all the strains and should be excluded from the proposed set.     

Bacteriophage typing of Salmonella weltevreden

Salmonella weltevreden has been found to be one of the commonest Salmonella serotypes isolated from diverse sources in India and has also been isolated in a number of other countries. A phage typing scheme was developed for this serotype using a set of six typing phages. These phages had been selected out of 146 phage strains isolated and purified from stool samples of man, laboratory animals and other animals, sewage and surface water sources, and the lytic mutants of temperate phages from S. weltevreden.The phage typing scheme was applied systematically to type the 946 strains from India isolated during 1958–1974 and 148 strains originating from Australia, Burma, England, Gan Island, Holland, Hong Kong, Malaysia, New Zealand, Papua New Guinea, The Philippines, Thailand, The United States and Vietnam during 1953–1971. The scheme was particularly studied to evaluate its utility in mapping the epidemiologically related strains from various sources.The S. weltevreden strains could be classified into ten phage types. Phage types 2 and 7 were found exclusively amongst Indian strains, type 6 from Vietnam and type 8 from Burma, Thailand and Vietnam. Phage types were found to be stable and consistent with the independent epidemiological data available.     

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.     

Comparison of Capsular Typing of Staphylococcus aureus with Bacteriophage Typing: A Study in Gulbarga, India

Staphylococcus aureus (S. aureus) is important both as a nosocomial and community acquired pathogen causing various degrees of infections. Typing S. aureus has been a question that is still being addressed. Bacteriophage typing is still used as a golden standard for typing though molecular methods are investigated. In developing countries where neither molecular typing nor the bacteriophage typing methods can be routinely used, the recently developed capsular typing method can be considered as screening method. We compared capsular typing with bacteriophage typing of the strains isolated in Gulbarga, India. We observed that the typeability of capsular typing was significantly higher (96%) among the phage typed strains, and the predominant capsular type in the region was type-8. The data so generated can be used to group S. aureus based on capsules both as a screening prior to bacteriophage typing, and to identify capsular candidate for developing prophylactic and therapeutic alternatives.     

Phage typing of cholera vibrios with different sets of phages]

A comparative study was made of two sets of Mukerjee and Drozhevkina-Arutyunova's bacteriophages in typing 514 strains of the El Tor vibrios and 45 strains of clasic biotype. It was shown that the Mukerjee or Drozhevkina-Arutyunova's phages could be used for the typing of cholera vibrios. The phages of the latter set prove to detect more phage types (18 against 11); they determine both the phage type and the biotype at the same time. The typing of cholera vibrios of both biotypes is possible, and the percentage of nontyping strains left is comparatively low (5.2 against 23.5 after Mukerjee). A table of the phage correspondence was made; it permits to obtain comparable data in using any set of the typing phages.     

Evaluation of the international phage typing set and some experimental phages for typing of Listeria monocytogenes from poultry in Spain

AIMS: The validity of the international phage set and 13 experimental phages for subtyping Listeria monocytogenes strains isolated from poultry in Spain was investigated. METHODS AND RESULTS: Ninety-six L. monocytogenes strains (52 from serogroup 1/2 and 44 from serogroup 4) were phage-typed using the international phage set, 10 experimental phages for typing serogroup 1/2 strains (seven isolated in France: 1313, 9425, 1807, 351, 881, 717 and 586-, and three from Denmark: 5775, 12682 and 6223-) and three experimental phages isolated in France for typing serogroup 4 strains (2425 A, 4286 and 197). Percentages of serogroup 1/2, serogroup 4 and total phage-typeable strains were 57.7%, 52.3% and 55.2%, respectively. Important differences in the behaviour of the phages tested were found. The typeability rate, the specificity index and the percentage of strong reactions were greater in the phages of international set than in the experimental phages. The number of phage typeable strains and the number of phage types (42) were not modified by the use of experimental phages. CONCLUSIONS: The phage set used was not effective for typing L. monocytogenes strains from poultry in Spain, because a low typeability rate was found. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results suggest the importance of the availability of new phages specific to a geographical area in order to improve the typeability of the system.     

Experimental phages for differentiating nontypable methicillin-resistant Staphylococcus aureus

The possibility of using phages, isolated from the lysogenic cultures of methicillin-resistant staphylococci and modified in methicillin-resistant cultures of phage 85, for the differentiation of nontypable staphylococcal strains has been studied. The variants of phage 85 cannot be used for the determination of differences between the strains of methicillin-resistant cultures; they are not suited for typing. For this purpose the collection of phages isolated from lysogenic methicillin-resistant cultures should be used.     

Phage typing and lysogen typing of Staphylococcus aureus]

A comparison was made between the results of phage and lysogenic typing of S. aureus strains isolated during several outbreaks of staphylococcal infection and S. aureus cultures isolated from the same carriers at different periods. The study of the groups of strains having the same origin showed that the differences in the number of reactions were more pronounced in lysogenic typing than in phage typing. For this reason lysogenic typing can be recommended only for the identification of those strains which cannot be identified with the use of the phages of the International Basic Set. The results of the experiments with induced phages proliferating in a restriction-defective strain indicated that restriction and modification were mainly responsible for the specificity of lytic reactions.     

Bacteriophage Typing as an Epidemiological Tool for Urinary Escherichia coli

Phage typing was used to identify strains of Escherichia coli isolated from urinary and nonurinary sources. When eight phages isolated in Pennsylvania were used to type 717 cultures from Missouri, 50.3% of 624 urinary isolates and 34.4% of 93 nonurinary isolates were typable. Strains from nonurinary sources were not found commonly in urine. When five additional phages isolated in Missouri were added to the original set of eight phages, 80.4% of 331 urinary isolates were typable. When this set of phages was used to type 552 urinary cultures isolated in California, Minnesota, Ohio, Pennsylvania, Virginia, and West Virginia, 82.0% of the cultures were typable. Some common phage types were found in high incidence among cultures from the different regions. No correlation was found between phage type and the pattern of resistance to antibiotics. Phage typing data were presented also on the number of strains in individual urine specimens and the recurrences of strains in patients with chronic bacteriuria. Of 97 fecal isolates, 75.2% of the cultures were typable, and the most common phage type was observed in high incidence among the urinary isolates from this region. When 75 cultures from nine other genera of enteric bacteria were typed, only the shigellae were lysed. In view of the information obtained by phage typing and the ease and speed with which it can be done, it is suggested that phage typing be considered a new tool in epidemiological studies of urinary tract infections by E. coli.     

Coagulase-negative Staphylococci isolated from patients. III. Phage typing

Coagulase-negative staphylococci of clinical origin were subjected to phage typing by means of phages from the experimental Dutch (Verhoef) and American (Paris) sets. These sets of phages were used to study 153 and 378 strains, respectively. The Dutch phages could lyse 30.1%, and the American ones 19.6% of the cultures. The strains belonging to the species S. epidermidis were lysed in 34.3% and 32.4% of cases, respectively, which is indicative of the fact that the American phages possess a more pronounced specificity in respect to S. epidermidis. The unsufficient effectiveness of typing phages does not yet allow one to evaluate the outlook for the method of phage typing in the study of coagulase-negative staphylococci.     

Phage Typing Scheme for Salmonella braenderup

A phage typing scheme for Salmonella braenderup based on both phage sensitivity and lysogenicity patterns is presented. Three S. braenderup symbiotic phages (br A, br B, and br C) were used in the phage sensitivity test, and three indicator strains were used for the lysogenicity test. The 424 strains examined were grouped in 15 of 64 possible types within this scheme. The most frequent types were: A(1) (32%), G(5) (21%), F(2) (14%), and H(1) (8%). All of the strains isolated successively from the same person belonged to the same type, as did the strains isolated from groups of individuals related to a common source.     

Typing ofSalmonella weltevreden strains by means of lysis patterns of symbiotic phages

A typing scheme forSalmonella weltevreden using the lysogenicity and lysis patterns of their carried phages is presented. Six strains ofS. weltevreden were selected for use as indicator strains for recognizing the lysis patterns of the carried phages. Two hundred and forty-five strains were examined and 207 were grouped in concurrence with the 15 lysis pattterns obtained out of 64 theoretically possible. Lysis pattern I (all 6 indicator strains lysed by the carried phage) included 24.5% of the strains. Thirty-eight strains (15.5%) were grouped as untypable because their lysates did not lyse any of the indicator strains. No correlation could be established between the lysis patterns of carried phages and the host and geographic distribution ofS. weltevreden.     

Panton-Valentine leukocidin gene sequence variation and phage in methicillin-resistant and methicillin-susceptible Staphylococcus aureus from children in mainland China

To determine the variation in the Panton–Valentine leukocidin (PVL) gene sequences and different PVL‐encoding phages of Staphylococcus aureus strains collected from children in mainland China, fifty‐eight strains with PVL collected from 2007 to 2009 were used. Their molecular characteristics were examined. Primers were designed to sequence the PVL genes. Six PVL‐encoding phages (?PVL, ?108PVL, ?SLT, ?Sa2MW, ?Sa2958, and ?Sa2USA) were identified by PCR. Eleven sequence types (ST) were detected with ST59 (39.7%, 23/58) the most frequent ST, followed by 910 (22.4%, 13/58), and 338 (12.1%, 7/58). Single nucleotide polymorphisms (SNP) were identified at 11 locations in the PVL genes. SNP (nucleotide 1396, A→G) and SNP (nucleotide 1546, A→G) were observed in >10 sequences. Four additional SNP were non‐synonymous. Both SNP (nucleotide 16, C→A) and SNP (nucleotide 62, C→T) were present in the same ST59 strain. SNP (nucleotide 527, A→G) was present in five strains belonging to ST30, 121, 1, and 93. SNP (nucleotide 1436, A→C) was present in one ST30 strain. Fifteen strains belonging to ST910, ST217, and ST30 carried a PVL phage that had an icosahedral head morphology. Nine ST59 strains carried ?108PVL. Three ST88 strains carried a PVL phage that had an elongated head morphology. Twenty‐seven strains, including 60.9% (14/23) of ST59 and all ST338 strains, had no detectable phage. In conclusion, sequence variation in PVL genes and PVL‐encoding phages was generally related to the lineage. ST59 strains may indeed carry novel PVL phages.     

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.     

Bacteriophage types represented by lactose-fermenting Salmonella agona strains

Bacteriophage typing was performed on 1911 S. agona, lactose-fermenting strains. These strains were isolated from hospitalised newborns and neonates patients. Out of 1911 strains 98.8% were typable by means of phage set prepared for strains differentiation of Salmonella agona showing typical biochemical properties. It was shown that in 16 provinces from which the strains were obtained in 1983-1985 type V (49.5%) and type XI (25.4%) prevailed. Subtypes VA and VB were distinguished within type V. Altogether 20.3% of strains were classified as belonging to these subtypes. Their lytic reaction was weaker with phages 3, 4, and 9 with the characteristic range of phage type V strains. Among tested strains types I, XIII, and XVI were also represented composing 2, 6, 0, 9, and 0.3% of total number of strains respectively. 1.5% of strains were nontypable and 0.2% showed lytic reactions different from that included in up to now used scheme of typing. It can be concluded that lactose-fermenting S. agona strains show susceptibility to lowered number of phages than typical for Salmonella species strains. It seems that differentiation of this atypical biochemical variant of S. agona with, the use of phage set used up to now may be also usefull in practice as it is the case in respect to strains with typical biochemical properties.     

Ambivalent bacteriophages of different species active on Escherichia coli K12 and Salmonella sps. strains

A study was made of several bacteriophages (including phages U2 and LB related to T-even phages of Escherichia coli) that grow both on E. coli K12 and on some Salmonella strains. Such phages were termed ambivalent. T-even ambivalent phages (U2 and LB) are rare and have a limited number of hosts among Salmonella strains. U2 and LB are similar to canonical E. coli-specific T-even phages in morphological type and size of the phage particle and in reaction with specific anti-T4 serum. Phages U2 and LB have identical sets of structural proteins, some of which are similar in size to structural proteins of phages T2 and T4. DNA restriction patterns of phages U2 and LB differ from each other and from those of T2 and T4. Still, DNAs of all four phages have considerable homology. Unexpectedly, phages U2 and LB grown on Salmonella bungori were unstable during centrifugation in a CsCl gradient. Ambivalent bacteriophages were found in species other than T-even phages and were similar in morphotype to lambdoid and other E. coli phages. One of the ambivalent phages was highly similar to well-known Felix01, which is specific for Salmonella. Ambivalent phages can be used to develop a new set for phage typing in Salmonella. An obvious advantage is that ambivalent phages can be reproduced in the E. coli K12 laboratory strain, which does not produce active temperate phages. Consequently, the resulting typing phage preparation is devoid of an admixture of temperate phages, which are common in Salmonella. The presence of temperate phages in phage-typing preparations may cause false-positive results in identifying specific Salmonella strains isolated from the environment or salmonellosis patients. Ambivalent phages are potentially useful for phage therapy and prevention of salmonellosis in humans and animals.