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.     

Lytic Activity of Vibrio Phages on Strains of Vibrio fetus Isolated from Man and Animals

Five phages isolated from lysogenic strains of Vibrio fetus var. venerealis and two from V. fetus var. intestinalis were tested for lytic activity on 95 V. fetus strains from various animal and human hosts. In addition, virion and plaque morphology of the seven phages were compared. Electron micrographs showed that all were the kite-tailed variety with minor variations in head and tail dimensions. Plaques of V45 and V2 were small, clear and irregular; those of V3, V8, and V19 were large, clear and regular at the edge; the plaques of V16 and V20 were intermediate in size, clear, and very irregular at the edge with satellite plaques. The number of strains lysed by one or more phages were as follows: 29 of 30 from cattle; 7 of 11 from sheep; 1 of 5 from pigs; 1 of 1 from a monkey; and 33 of 42 from human hosts. Four natural groups of phages were derived by statistical measures of percentage of similarity in lytic activity. Group III lysed more strains (46 of 95) than any of the others. Twenty-five strains were lysed by group IV, 23 strains by group I, and 19 strains by group II. Results of this study indicate that phage typing should be a practical supplement to other differential tests for V. fetus.     

Phage types of Staphylococcus aureus isolated in Poland in 1999-2004

The aim of study was to determine how population of Staphylococcus aureus strains from hospital environment forms itself with respect to phage types and frequency of their occurrence recently. 1157 S. aureus isolated from various clinical materials between 1999 and 2004 have been investigated. The basic set of phages and the three additional ones were used for typing strains according to Blair and Williams method. The results proved that population of S. aureus strains isolated from hospital environment differentiates with respect to phage types, like in the past. Strains belonging to phage group II dominates among them, but a considerable increase in number of phage group III have been remarked lately. A differential value of an individual phages from basic set remains on their usual level for years.     

Typing of Nontypable Staphylococci by Lysogeny

Strains of coagulase-positive staphylococci which were nontypable with the routine typing set of phages could be typed by lysogeny with phage-propagating strains as indicators and with ultraviolet induction. About 10% of the strains could be typed without induction. About 36% of them could be typed by this method when ultraviolet irradiation was used as an inducing agent. The phage groups from which the majority of the nontypable staphylococci originated were easily identified by this method of typing.     

Plaque morphology and antigenic relationship of the Salmonella weltevreden typing phages

The plaque morphology and antigenic relationship of the six typing phages of Salmonella weltevreden were studied. Under identical conditions of plating, the phages could be classified into three groups based on plaque morphology. Neutralization tests with anti-phage sera showed that typing phages phi I and phi II were antigenically similar. Phages phi III, phi IV and phi VI also showed antigenic similarity. Typing phage phi V was antigenically distinct from all other phages. Thus the phages could be classified into three groups on the basis of both plaque morphology on their respective indicator strains and velocities of neutralization by homologous/heterologous anti-sera.     

Bacteriophage typing of Listeria species.

A bacteriophage typing scheme for differentiating Listeria isolates from dairy products and various other foodstuffs was developed. Sixteen selected phages isolated from both environmental sources and lysogenic strains were used for typing and, according to their lytic spectra, divided into four groups. Thus far, 41 distinct patterns of lysis were seen when this set was used in typing 57 defined reference strains, representing all five confirmed species and 16 serotypes in addition to 454 Listeria isolates of primarily foodborne origin. Overall, typability was 84.5%; i.e., a strain was lysed by at least one phage at 100x routine test dilution. Strains belonging to serovar 3 were mostly resistant to lysis by the phages employed. The results were highly reproducible, as determined in retyping trials several weeks later. Some phages isolated from environmental sources showed a wider lytic spectrum than did those isolated from lysogenic strains. In accordance with this, the phages were found in different clusters within a computer-generated linkage map. Species specificity and serovar specificity of the lytic reaction were not found. None of the phages was able to lyse strains of Listeria grayi, Listeria murrayi or Jonesia denitrificans. This phage typing system may provide important information for a means of recognizing and eliminating sources of contamination by Listeria spp. within dairy plant equipment.     

Bacteriophage Typing of Proteus mirabilis, Proteus vulgaris, and Proteus morganii

A bacteriphage typing scheme for differentiating Proteus isolated from clinical specimens was developed. Twenty-one distinct patterns of lysis were seen when 15 bacteriophages isolated on 8 Proteus mirabilis, 1 P. vulgaris, and 1 P. morganii were used to type 162 of 189 (85.7%) P. mirabilis and P. vulgaris isolates. Seven phages isolated on 3 P. morganii were used to type 13 of 19 (68.4%) P. morganii isolates. Overall, 84.1% of the 208 isolates were lysed by at least 1 phage at routine test dilution (RTD) or 1,000 x RTD. Fifty isolates, retyped several weeks after the initial testing, showed no changes in lytic patterns. The phages retained their titers after storage at 4 C for several months. A computer analysis of the data showed that there was no relationship between the source of the isolate and bacteriophage type. This bacteriophage typing system may provide epidemiological information on strains involved in human infections.     

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.     

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.     

F-specific RNA bacteriophages and sensitive host strains in faeces and wastewater of human and animal origin

Faeces of humans, pigs, cattle and chickens were investigated for the presence of somatic coliphages, F-specific bacteriophages and Escherichia coli strains sensitive to infection by F-specific phages. Attention was given to the possible effect of age and use of antibiotics on the prevalence of the FRNA phages and sensitive E. coli strains. Somatic coliphages were often detected in high numbers in all types of faeces. In contrast, FRNA phages were rarely detected in faeces from humans and cattle but more often in faeces from pigs and adult chickens. Samples from young chickens (with or without antibiotics) were consistently positive for FRNA phages (up to 3 x 10(6) pfu/g). F-specific RNA phages were found in substantial numbers (greater than 10(3) pfu/ml) in a variety of wastewaters: domestic, hospital, slaughterhouses and occasionally in 'grey water'. Their origin in wastewater was not clear. Strains from faeces usually belonged to serogroups I and IV. These types were also found in wastewater, as were group II and III strains. Serogroup II phages were abundant in wastewater of human origin but rare in faeces. Escherichia coli strains sensitive to infection by F-specific phages were common in faeces (overall 290/1081: 27%). No strains with fully depressed F-pilus synthesis were detected among the sensitive strains. It is concluded that the occurrence of F-specific RNA bacteriophages in water points to sewage pollution rather than faecal pollution; the mechanism of replication of these organisms in wastewater is not understood.     

F-specific RNA bacteriophages and sensitive host strains in faeces and wastewater of human and animal origin

Faeces of humans, pigs, cattle and chickens were investigated for the presence of somatic coliphages, F-specific bacteriophages and Escherichia coli strains sensitive to infection by F-specific phages. Attention was given to the possible effect of age and use of antibiotics on the prevalence of the FRNA phages and sensitive E . coli strains. Somatic coliphages were often detected in high numbers in all types of faeces. In contrast, FRNA phages were rarely detected in faeces from humans and cattle but more often in faeces from pigs and adult chickens. Samples from young chickens (with or without antibiotics) were consistently positive for FRNA phages (up to 3 × 10⁶ pfu/g). F-specific RNA phages were found in substantial numbers (> 10³ pfu/ml) in a variety of wastewaters: domestic, hospital, slaughterhouses and occasionally in 'grey water'. Their origin in wastewater was not clear. Strains from faeces usually belonged to serogroups I and IV. These types were also found in wastewater, as were group II and III strains. Serogroup II phages were abundant in wastewater of human origin but rare in faeces. Escherichia coli strains sensitive to infection by F-specific phages were common in faeces (overall 290/1081: 27%). No strains with fully derepressed F-pilus synthesis were detected among the sensitive strains. It is concluded that the occurrence of F-specific RNA bacteriophages in water points to sewage pollution rather than faecal pollution; the mechanism of replication of these organisms in wastewater is not understood.     

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.     

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.     

Distribution of RNA coliphages in Senegal, Ghana, and Madagascar

The distribution patterns of RNA coliphages (phages) in Senegal, Ghana, and Madagascar were investigated by collecting sewage samples from domestic drainage in November, 1980. In Senegal, among 65 sewage samples collected mainly from Dakar and its vicinity, 14 (22%) contained RNA phages (16 strains). By serological analysis, 13 of 16 strains were found to belong to group III. This is consistent with the distribution pattern of RNA coliphages in tropical and subtropical regions of Asia. In Ghana, however, among 106 samples collected from Accra, Suhum, and their vicinities, only seven (7%) contained RNA phages (seven strains) (groups I, II, and III [1:3:3]). In Madagascar, among 124 samples collected from Antananarivo, Moramanga, and their vicinities, seven (6%) contained RNA phages (seven strains) (groups I, II, III, and IV [1:1:1:4]). In spite of the low isolation frequency, it can be said that Madagascar appears to have a unique distribution pattern (abundance of group IV phages) which differs from that of any other countries we have examined. The generality of the distribution pattern of RNA phages in the tropical region (abundance of group III phages) was thus verified at least in Senegal.     

应用肠杆菌科诊断噬菌体检测志贺氏菌的评价

应用肠杆菌科诊断噬菌体对2280株疑似志贺氏菌进行了检测,同时进行了常规鉴定。结果表明,志贺氏菌属Sh噬菌体10³RTD对属内裂解率为100%,1RTD为99.9%;65株与志贺氏菌分型血清呈现凝集的非志贺氏菌,10³RTD裂解率为12.3%,1RTD为4.6%。裂解模式的测定表明,2215株志贺氏菌分属于7个裂解模式,仅模式3中3株鲍氏5型为文献[2,3]所未列入,余者完全一致。Sh10³RTD裂解的非志贺氏菌均可用1RTD和裂解模式排除     

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.     

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.     

Enterotoxins and phage typing of Staphylococcus aureus isolated from clinical material and food in Libya

Enterotoxin was detected in 22 (61.1%) of the 36 S. aureus strains isolated from clinical materials and in 3 (13%) of the 23 S. aureus strains from food samples (P < 0.05). On the basis of individual types of enterotoxin, staphylococcal enterotoxin A (SEA) was produced by 11.1%, SEB by 38.9% and SEC by 22.2% of SS. aureus strains from clinical material. Of the food S. aureus strains, SEC and SED produced by 8.7% and 4.3% respectively. Of the clinical and food S. aureus strains, 52.8% and 39.1%, respectively, were typeable by the 23 phages of International Phage Set. The majority of the typeable S. aureus strains from clinical and food sources belonged to group II being at 22.2% and 17.4% respectively. Furthermore, of the 14 SEB-producing S. aureus, 42.9% were of phage group II. In conclusion, the results obtained indicate that enterotoxin-producing S. aureus strains from clinical materials in Libya are not uncommon; however, certain foods appear not to be the source of such strains. Because of the low susceptibility to bacteriophages shown by S. aureus isolated in Libya, compared to reports from several countries, other methods of typing should be used in conjunction with phage typing in epidemiological investigations concerning this organism.     

Evaluation of seven experimental phages for inclusion in the international phage set for the epidemiological typing of Listeria monocytogenes.

The purpose of our study was to evaluate the inclusion of seven experimental phages into the international phage set for subtyping Listeria monocytogenes. The seven additional phages included the broad-host-range virulent Myoviridae phage A511 (M. J. Loessner, Appl. Environ. Microbiol. 57:1912-1918, 1991), three temperate phages from the Danish subsystem for typing serotype 1/2 strains (12682, 6223, and 5775) (P. Gerner-Smidt, V.T. Rosdahl, and W. Frederiksen, APMIS 101:160-167, 1993), and three temperate phages isolated by this laboratory in France (9425, 1313, and 197). A panel of 395 Listeria monocytogenes isolates (including 180 that were non-phage typeable by the international set) were used in the study for a comparison of the lytic spectra of the various bacteriophages. These results showed that the inclusion of five of the experimental phages contributed greatly to the overall typeability and discriminatory power of the system, especially for strains within serogroup 1/2.