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At least 19 recordsLinked to original sources
PubMed1997

Source of variation detected in ribotyping patterns of Haemophilus influenzae: comparison of traditional ribotyping, PCR-ribotyping and rDNA restriction analysis.

The pattern of EcoRI restriction fragments of chromosomal DNA that hybridize with a probe for genes encoding 16S and 23S rRNA is highly discriminatory for non-capsulate Haemophilus influenzae (NCHI). The source of variation detected by these probe-based ribotyping patterns was investigated by restriction analysis of rRNA operon (rrn) amplification products from nine representative strains. Digestion of rrn amplification products with EcoRI indicated one conserved EcoRI site within 16S rDNA and no EcoRI sites within the 16S-23S intergenic spacer region of the nine strains, and an EcoRI site at the 5' end of 23S rDNA from seven of the nine strains. Comparison of the EcoRI ribotyping patterns obtained with separate probes for 16S and 23S rDNA showed more variation with the 23S probe indicating variation in EcoRI sites downstream from the operon. Restriction analyses of 16S and 23S rDNA amplification products with AluI, HhaI, HaeIII and TaqI divided the nine 'traditional' ribotypes into a maximum of three and eight groups, respectively. Similar analyses of the 16S-23S intergenic regions (PCR-ribotyping) failed to distinguish any of the nine representative strains. Therefore, there is probably insufficient variation within the operon for it to form a good target for PCR-based typing methods. In contrast, 'traditional' ribotyping with cDNA from 16S plus 23S rRNA detects restriction site differences in the sequences flanking the operon, which show considerably more variation between strains. 'Traditional' ribotyping should therefore remain the standard for characterising NCHI in epidemiological investigations.

Bacterial Typing Techniques↗
PubMed1999

Optimized ribotyping protocol applied to Hungarian Bordetella bronchiseptica isolates: identification of two novel ribotypes.

We reported previously that ribotype patterns generated with PvuII and a probe derived from the Escherichia coli rrnB gene could be used to differentiate isolates of Bordetella bronchiseptica. In the present study we report modifications made to the original ribotyping procedure that permit detection in the formerly characterized isolates of an additional 8 fragments with homology to rrnB. Ribotypes were redefined to include these fragments. Although this modification did not permit the detection of novel ribotypes from the previously characterized isolates, it did result in a more accurate reclassification of five of these isolates to other existing ribotypes. It was hypothesized that the additional fragments could form the basis for novel ribotypes in future analyses, and this was supported by the subsequent evaluation of 101 previously uncharacterized pig, rabbit, and dog B. bronchiseptica isolates from Hungary. A total of six different patterns were detected from this group, including two previously not identified that were designated ribotypes 17 and 18. The profile of ribotype 17 includes a novel fragment not associated with any other ribotype. A subset of the fragments constituting ribotype 18, essential for its differentiation from other ribotypes, is only detectable under the modified conditions reported here. Hungarian swine isolates are highly clonal, since 98.2% were identified as ribotype 3. Similarly, 83.7% of rabbit isolates from Hungary are also ribotype 3. Cluster analysis revealed that despite the existence of numerous ribotypes, B. bronchiseptica isolates display limited heterogeneity. The ability to detect additional ribotypes under the modified conditions described in this study strengthens the usefulness of ribotyping as an epidemiologic tool.

Animals↗
PubMed1993

Ribotyping of selected isolates of Enterobacter cloacae and clinical data related to biotype, phage type, O-serotype, and ribotype.

In order to evaluate if ribotyping of selected isolates of Enterobacter cloacae could further elucidate the epidemiology, we performed ribotyping of 109 isolates indistinguishable by bio-, phage-, and O-serotyping, with inconclusive typing results, or from patients with more than one isolate. Ribotyping provided additional information, and some cases of cross-infection or common source of infection were revealed. Under the supposition that isolates sharing the same ribotype were of the same origin, problems arose with respect to bio-, O-sero, as well as phage typing; in particular a remarkable number of isolates showed differences in phage type. In order to identify possible virulence characteristics of certain types, clinical data were related to bio-, phage-, O-sero-, and ribotype. Biotype 66 was significantly more frequent among blood culture isolates (P = 0.001), but this might have reflected the presence of a certain strain in the environment of the intensive care unit, where patients were more likely to develop bacteraemia; serotype 04 was significantly more frequent among isolates from the urinary tract (P = 0.02), and serotype 013 was more frequent among women (P = 0.05). One ribotype was found only among community-acquired isolates, which might suggest that it is a frequent but less virulent strain.

Bacteriophages↗
PubMed1999

Comparison of conventional ribotyping and PCR-RFLP ribotyping for the analysis of endemic strains of Neisseria meningitidis isolated in a local community over 7 years.

Conventional ribotyping was compared with the PCR amplification of the intergenic spacer region between 16S and 23S rRNA genes (PCR-RFLP ribotyping) when applied to the subtyping of sporadic Neisseria meningitidis strains. Thirty isolates out of a total of 36 meningococcal disease cases, reported as having occurred in a particular community over a 7-year endemic period, were analyzed by each of the methods. Only ribotyping with three restriction enzymes (EcoRI, ClaI and XhoI) gave acceptable discriminatory power for short-term epidemiological purposes. We conclude that conventional ribotyping is a suitable method for typing sporadic meningococcal strains and that it cannot be replaced by the more straightforward PCR-RFLP ribotyping method.

Bacterial Typing Techniques↗
PubMed1998

Genetic heterogeneity of clinical strains of Yersinia enterocolitica traced by ribotyping and relationships between ribotypes, serotypes, and biotypes.

A series of 74 Yersinia enterocolitica clinical strains collected in a Spanish region and 10 reference strains, assigned to nine serotypes and five biotypes, were analyzed by ribotyping procedures. Riboprobing, performed separately with HindIII and BglI and using an rrn operon as the probe, generated 13 and 11 ribotypes (discrimination index [DI] = 0.56 and 0.55), respectively. PCR ribotyping, performed with primers complementary to conserved regions of 16S and 23S rRNA genes, generated 13 ribotypes (DI = 0. 56). A combination of data from the three procedures allowed for further discrimination into 17 combined ribotypes (DI = 0.83). The dendrogram obtained by cluster analysis of data from riboprobing indicated a high heterogeneity of the ribosomal DNA regions of the strains under study (similarities between 10 and 92%), which were grouped into three clusters at a similarity level of 0.32. The major cluster included 10 branches, and 7 of these formed a subcluster (similarity coefficient, >83%) represented by strains of serotype O:3 and biotype 2, 3, or 4. The second cluster included four branches, represented by strains belonging to seven non-O:3 serotypes, biotypes 1A and 2, and two of these branches included pyrazinamidase-positive as well as pyrazinamidase-negative strains. The remaining three branches, represented by O:3-biotype 4 strains, formed a third cluster weakly related to the others. Data from this study showed that Y. enterocolitica O:3 organisms assigned to a prevalent and endemic lineage and non-O:3 organisms assigned to three other less-frequent lineages are circulating and causing human disease in the Spanish region under study.

Bacterial Typing Techniques↗
PubMed1998

Molecular epidemiology by ribotyping and PCR-ribotyping of Enterococcus faecium strains isolated from intercontinental areas.

In this study classical ribotyping based on hybridization of an enteroccocal ribosomal operon previously cloned from Enterococcus hirae (Sechi and Daneo-Moore, 1993) with XbaI cut chromosomal DNA and PCR-ribotyping were used to characterize the molecular epidemiology of 131 Enterococcus faecium, with high-level resistance to gentamicin, isolated from different hospitals in Italy and the United States. The ribotyping was able to differentiate all 131 clinical isolates into 96 family patterns. These family patterns appeared to be useful in establishing epidemiological spread. The results obtained were in agreement with those previously published, suggesting the presence of five to six operons in the Enterococcus genus (Sechi et al., 1994). We performed PCR-ribotyping, based on conserved sequences at the 3' end of the enterococcal 16S rrn and the 5' end of the 23S rrn, on 131 clinical isolates as well as on several enterococcal ATCC strains tested. The results were then compared with those obtained with the classical ribotyping method. The results suggest the presence of at least four classes of intergenic spacers among enterococci, but these classes are not helpful in differentiating between Enterococci or among Enterococcal isolates.

DNA, Bacterial↗
PubMed1999

Molecular characterization of Streptococcus equi subspecies equi isolated from an Ethiopian camel by ribotyping and PCR-ribotyping.

The aim of this study was to characterize a S. equi subspecies equi strain isolated from an Ethiopian camel by different molecular techniques (Ribotyping and PCR-Ribotyping). We compared the results obtained with those generated from two strains of the Pasteur Collection. The ribotyping showed the highest power of differentiation, distinguishing between the strains analyzed, whereas PCR-Ribotyping was able only to differentiate the camel isolate but not the strains from the Pasteur Collection. The application of this technique will be very useful to establish a clonal relationship among equine and camelids strains and help the prevention and cure of the equine and camel pathology.

Animals↗
PubMed1998

Outbreak of Staphylococcus schleiferi wound infections: strain characterization by randomly amplified polymorphic DNA analysis, PCR ribotyping, conventional ribotyping, and pulsed-field gel electrophoresis.

Within a 1-year period, six surgical-site infections (SSI) caused by Staphylococcus schleiferi were observed in the department of cardiac surgery of Ignatius Hospital, Breda, The Netherlands. Since outbreaks caused by this species of coagulase-negative staphylococci have not been described before, an extensive environmental survey and a case control study were performed in combination with molecular typing of the causative microorganism in order to identify potential sources of infection. Variability, as detected by four different genotyping methods (random amplification of polymorphic DNA [RAPD], conventional and PCR-mediated ribotyping, and pulsed-field gel electrophoresis [PFGE] of DNA macro restriction fragments), appeared to be limited both among the clinical isolates and among several control strains obtained from various unrelated sources. Among unrelated strains, RAPD and PCR-mediated ribotyping identified two types only, whereas seven different types were identified in a relatively concordant manner by conventional ribotyping and PFGE. The latter two procedures proved to be the most useful tools for tracking the epidemiology of S. schleiferi. Four of the outbreak-related strains were identical by both methods, and two isolates showed limited differences. In the search for a potential source of S. schleiferi infection, two slightly different PFGE types were encountered on several occasions in the nose of a single surgeon. These strains were, however, clearly different from the outbreak type. In contrast, S. schleiferi cultures remained negative for two persons identified on the basis of case control analysis. It was demonstrated that SSI caused by S. schleiferi had a clinical impact for patients comparable to that of a wound infection caused by Staphylococcus aureus. This report describes the first well-documented outbreak of S. schleiferi infection. A source of the outbreak was not detected.

Aged↗
PubMed2003

[Comparison of AP-PCR methods, ribotyping (PCR-ribotyping) and pulsed-field electrophoresis (PFGE) for strains of Clostridium difficile producing toxin B and not producing toxin A].

In this study were used AP-PCR, PCR-ribotyping and pulsed-field elecrophoresis (PFGE) for comparative study of toxin A-negative/toxin B-posi-tive Clostridium difficile strains with deletion in toxin A gen. We investigated nine unrelated clinical strains, isolated from different units and different time from patients suffering to antibiotic associated diarrhea (AAD). We found that toxin A-negative/toxin B-positive C. difficile strains isolated in Poland belonging to a single genotype A, are being similar to the Japanese strains.

Bacterial Toxins↗
PubMed2001

Molecular epidemiologic features and antimicrobial susceptibility profiles of various ribotypes of Pseudomonas aeruginosa isolated from humans and ruminants.

OBJECTIVES: To assess automated ribotyping for characterization of Pseudomonas aeruginosa isolates and to identify their type prevalence and geographic distribution. SAMPLE POPULATION: 39 human and 56 ruminant P aeruginosa isolates. PROCEDURES: Isolates were identified by use of bacteriologic techniques and automated Pvull-based ribotyping. Susceptibility to antimicrobials was tested in vitro. Data were analyzed for index of discrimination; prevalence ratio; geographic distribution of ribotypes found only in humans, only in cows, or only in goats (single-host ribotypes); and geographic distribution of ribotypes found in humans and ruminants (multihost ribotypes). RESULTS: All isolates were typeable (45 ribotypes, 35 single-host ribotypes). Ribotyping index of discrimination was 0.976. More isolates (45.3%) than expected yielded multihost ribotypes (22% of all ribotypes). Although 8.6% of single-host ribotypes were found in 4 or more isolates, 60% of multihost ribotypes were found in 4 or more isolates. Ninety percent of multihost ribotypes were isolated from different geographic areas, whereas 3.0% of single-host ribotypes were isolated from different geographic areas. All ruminant isolates were susceptible to gentamicin and polymyxin B. In contrast, antibiogram profiles differed for human isolates from different geographic areas. Susceptibility to antimicrobials differentiated 6 isolates not distinguished by ribotyping. CONCLUSIONS AND CLINICAL RELEVANCE: Automated ribotyping with Pvull discriminated more isolates than in vitro antimicrobial susceptibility. In combination, both tests provided more information than either test alone. Given the greater prevalence and geographic distribution of multihost ribotypes, immunocompromised humans and lactating ruminants may have a greater risk for disease if exposed to multihost P aeruginosa ribotypes, compared with single-host ribotypes.

Animals↗
PubMed1998

Evaluation and application of ribotyping for epidemiological studies of Actinobacillus pleuropneumoniae in Denmark.

The aim of the present study was to evaluate ribotyping as an epidemiological tool for Actinobacillus pleuropneumoniae and apply the method in studies of A. pleuropneumoniae infections in Danish pig herds. The evaluation of ribotyping was based on the 13 international reference strains and 106 epidemiologically unrelated Danish field strains representing the nine serotypes of biotype 1 (1, 2, 5A/B, 6, 7, 8, 10, 12, and K2:O7) and one serotype 14 of biotype 2. Enzymes CfoI and HindIII were chosen for generation of ribotype patterns. Ribotyping of the reference strains resulted in 10 CfoI types and 11 HindIII types. Ribotyping of the Danish strains resulted in 17 different CfoI ribotypes and 24 different HindIII ribotypes. Combining HindIII- and CfoI-ribotyping divided the Danish strains into 26 different types. The stability, reproducibility and typability of ribotype patterns were good, and the discriminatory power was between 0.85-0.89. The relatively low discriminatory power was caused by four predominant types, containing 61% of the isolates. The typing system was applied in studies of routes of infection of specific pathogen-free (SPF) pig herds and included 112 strains of A. pleuropneumoniae. Airborne transmission from neighboring conventional pig farms was investigated in 12 cases of infected SPF herds. Transmission via vehicles transporting pigs between SPF herds was investigated in nine cases while transmission by trading of pigs between SPF herds was investigated in two cases. Serotype 2 was isolated from all SPF herds included in this study, except one, emphasizing the high prevalence of this serotype in Denmark. By ribotyping, airborne transmission was indicated in five of 12 cases, transmission via pig transporting vehicle was indicated in six of nine cases, and transmission via trading was indicated in one of two cases. In many cases findings of predominant ribotypes made interpretations of suspected routes of transmission difficult. The relationship of strains based on ribotypes was calculated using Dices coefficient and clustered by UPGMA. HindIII ribotypes of serotype 2 strains were closely related, though only showing 43% similarity to HindIII ribotypes of remaining serotypes.

Actinobacillus Infections↗
PubMed1993

Epidemiologic application of a standardized ribotype scheme for Vibrio cholerae O1.

A standardized scheme of 27 different BglI ribotypes and subtypes of Vibrio cholerae O1 strains is proposed on the basis of data from 214 human and environmental strains isolated in 35 countries and 14 U.S. states over the past 60 years. The ribotype patterns obtained are reproducible and stable over time. Seven different but very similar ribotypes (1a to 1g) were observed among 16 strains of the classical biotype. Twenty ribotypes and subtypes were identified among 198 V. cholerae O1 strains of the El Tor biotype. Six different patterns were found among the strains causing the current seventh pandemic. Strains of ribotype 8 originated only in central African countries, while those of ribotype 3 originated mainly in Asia and the Pacific Islands. The most widely distributed strains were those of ribotype 6, which was subdivided into three very similar but still distinguishable subtypes. The present Latin American epidemic is caused by strains of ribotype 5. Strains of this ribotype were isolated from several other geographic locations but can be differentiated from the Latin American strains by other molecular methods. Strains associated with two documented environmental reservoirs exhibited three distinct ribotype patterns; those isolated from patients who ate food from the U.S. Gulf waters were all of ribotype 2, while the strains related to the northeast Australian rivers were of ribotypes 9 and 10. Nontoxigenic V. cholerae O1 strains originating in Latin America and the U.S. Gulf Coast did not form a specific cluster of ribotypes. Ribotyping in combination with other well-defined methods can assist in epidemiologic investigations, helping to trace the movement of strains and to identify their geographic origins.

Animals↗
PubMed1994

Characterization of PCR-ribotyping for Burkholderia (Pseudomonas) cepacia.

Ribotyping, a method of genotyping bacterial isolates for epidemiologic study, uses rRNA as a probe to detect chromosomal restriction fragment length polymorphisms. Although ribotyping is accurate, its utility is limited by the labor and time necessary for Southern blot analysis. PCR-ribotyping uses PCR to amplify the 16S-23S intergenic spacer region of the bacterial rRNA operon. Length heterogeneity in the spacer region has previously been found to be useful as an alternative to standard ribotyping in a study of Burkholderia (Pseudomonas) cepacia. To further analyze the accuracy of PCR-ribotyping, three groups of previously characterized isolates of B. cepacia were investigated. PCR-ribotyping grouped 90 isolates recovered from seven well-defined epidemics into the correct outbreak group with a mean concordance of 93%. Both standard ribotyping and PCR-ribotyping separated 15 unrelated isolates into 14 types. In an analysis of 83 B. cepacia isolates from chronically colonized cystic fibrosis patients, the concordance of PCR-ribotyping with standard ribotyping ranged from 83 to 100%, with a mean of 98%. One isolate from a chronically colonized patient had a different type by standard ribotyping but was identical to the other isolates from this patient by PCR-ribotyping. Thus, PCR-ribotyping is a rapid and accurate method for typing B. cepacia and is less labor intensive than standard ribotyping.

Base Sequence↗
PubMed1999

Associations of Streptococcus suis serotype 2 ribotype profiles with clinical disease and antimicrobial resistance.

A total of 122 Streptococcus suis serotype 2 strains were characterized thoroughly by comparing clinical and pathological observations, ribotype profiles, and antimicrobial resistance. Twenty-one different ribotype profiles were found and compared by cluster analysis, resulting in the identification of three ribotype clusters. A total of 58% of all strains investigated were of two ribotypes belonging to different ribotype clusters. A remarkable relationship existed between the observed ribotype profiles and the clinical-pathological observations because strains of one of the two dominant ribotypes were almost exclusively isolated from pigs with meningitis, while strains of the other dominant ribotype were never associated with meningitis. This second ribotype was isolated only from pigs with pneumonia, endocarditis, pericarditis, or septicemia. Cluster analysis revealed that strains belonging to the same ribotype cluster as one of the dominant ribotypes came from pigs that showed clinical signs similar to those of pigs infected with strains with the respective dominant ribotype profiles. Furthermore, strains belonging to different ribotype clusters had totally different patterns of resistance to antibiotics because strains isolated from pigs with meningitis were resistant to sulfamethazoxazole and strains isolated from pigs with pneumonia, endocarditis, pericarditis, or septicemia were resistant to tetracycline.

Animals↗
PubMed1996

Recovery of different Listeria ribotypes from naturally contaminated, raw refrigerated meat and poultry products with two primary enrichment media.

Isolation rates for Listeria monocytogenes and the other Listeria spp. typically improve when samples are enriched in more than one primary enrichment medium. This study evaluated the abilities of two primary enrichment media, University of Vermont-modified Listeria enrichment broth (UVM) and Listeria repair broth (LRB), to recover different ribotypes of Listeria spp. from raw meat and poultry samples. Forty-five paired 25-g retail samples of ground beef, pork sausage, ground turkey, and chicken (160 samples) underwent primary enrichment in UVM and LRB (30 degrees C for 24 h) followed by secondary enrichment in Fraser broth (35 degrees C for 24 and 40 h) and plating on modified Oxford agar. After 24 h of incubation of 35 degrees C, 608 Listeria colonies from selected positive samples were biochemically confirmed as L. monocytogenes (245 isolates), L innocua (276 isolates), and L. welshimeri (89 isolates) and then ribotyped with the automated Riboprinter microbial characterization system (E. I. du Pont de Nemours & Co., Inc.). Thirty-six different Listeria strains comprising 16 L. monocytogenes (including four known clinical ribotypes), 12 L. innocua, and 8 L. welshimeri ribotypes were identified from selected positive samples (15 samples of each product type; two UVM and two LRB isolates per sample). Twenty-six of 36(13 L. monocytogenes) ribotypes were detected with both UVM and LRB, whereas 3 of 36 (1 L. monocytogenes) and 7 of 36 (3 L. monocytogenes) Listeria ribotypes were observed with only UVM or LRB, respectively. Ground beef, pork sausage, ground turkey, and chicken yielded 22 (8 L. monocytogenes), 21 (12 L. monocytogenes), 20 (9 L. monocytogenes), and 19 (11 L. monocytogenes) different Listeria ribotypes, respectively, with some Listeria ribotypes confined to a particular product. More importantly, major differences in both the number and distribution of Listeria ribotypes, including previously recognized clinical and nonclinical ribotypes of L. monocytogenes, were observed when 10 UVM and 10 LRB isolates from five samples of each product were ribotyped. When a third set of six samples per product type was examined from which two Listeria isolates were obtained by using only one of the two primary enrichment media, UVM and LRB failed to detect L. monocytogenes (both clinical and nonclinical ribotypes) in two and four samples, respectively. These findings stress the importance of using more than one primary enrichment medium and picking a sufficient number of colonies per sample when attempting to isolate specific L. monocytogenes strains during investigations of food-borne listeriosis.

Animals↗
PubMed2000

Ribotype diversity of porcine Pasteurella multocida from Australia.

OBJECTIVE: To use the technique of ribotyping to investigate the genetic diversity of Australian isolates of Pasteurella multocida associated with outbreaks of clinical disease in Australian pigs. DESIGN: One hundred and seven porcine P multocida isolates were analysed by ribotyping using the restriction enzymes HpaII and HindIII. The genetic population structure of the Australian porcine P multocida isolates was determined through statistical analysis of the joint ribotype patterns, and this was then compared with biochemical and epidemiological data available for the population. RESULTS: A total of 25 combined ribotypes were recognised, which were grouped into five ribotype clusters. Despite the deliberate selection of diverse isolates, the study revealed only a limited degree of genetic diversity. Fourteen of the ribotypes contained multiple isolates, and 12 of these ribotypes were present on more than one farm. Three of the seven biovars analysed in the study showed very limited diversity. All fifteen biovar 2 isolates (subsp multocida) were found in a single cluster (III), while all four biovar 8 isolates, which correspond to P multocida subsp gallicida, were allocated by themselves to a single cluster (IV). All nine of the biovar 12 isolates (lactose-positive subsp multocida) were assigned to a single cluster (I), together with the single biovar 14 isolate, which was the only other lactose-positive isolate in the population (ODC-negative). CONCLUSION: A limited number of ribotypes of P multocida are associated with Australian pigs. The majority of these ribotypes are widely distributed across multiple farms, and across multiple states. Individual farms can possess multiple ribotypes of P multocida. Some of the unusual biochemical variants of P multocida present in Australian pigs have a very limited genetic diversity. The nature of pig production in Australia, primarily involving continuous flow systems with few closed herds, has possibly contributed to the widespread distribution of a limited number ribotypes.

Animals↗
PubMedDate not supplied

Putative temporal variability of Escherichia coli ribotypes from yearling steers.

Escherichia coli is a ubiquitous component of the intestinal microflora of warm-blooded animals, and is an indicator of fecal contamination of surface waters. Ribotype profiling of E. coli is one of several genotypic methods that has been developed to determine the host origin of fecal bacteria. Like most genotypic methods of source tracking, ribotyping requires a host origin database to identify environmental isolates. To determine the extent of temporal variability of ribotypes and its effect on a host origin database, E. coli isolates were obtained from fecal samples of two herds of Black Angus steers at a long-term experimental site at four sampling times from October 1999 to July 2000. Fecal samples were taken from six randomly chosen steers at each time. At a similarity index of 90% as calculated by unweighted pair-group method using arithmetic averages (UPGMA), 240 ribotypes were identified from 451 E. coli isolates. Only 20 ribotypes (8.3%), comprising 33% of the total isolates, were shared among sampling times and were considered resident ribotypes. Two of the twenty resident ribotypes appeared at three sampling times, and the remaining eighteen appeared at two. The majority of the ribotypes, therefore, were transient and unique to each sampling time and steer. Both the apparent turnover of E. coli ribotypes and a clonal diversity index of 0.97 (indicative of extensive ribotype variability) suggest the necessity of ribotyping a large number E. coli isolates per host to establish a host origin database that is independent of temporal variability, or complete enough to be effective.

Animals↗
PubMed1998

Evaluation of PCR-based methods and ribotyping performed with a mixture of PstI and SphI to differentiate strains of Salmonella serotype Enteritidis.

The capacity to differentiate Salmonella serotype Enteritidis strains by PCR ribotyping; RAPD typing with three arbitrary primers and ribotyping with a mixture of PstI and SphI or 'PS ribotyping', was evaluated on a series of 65 strains associated with human infections and 11 reference strains. The series had been analysed previously by phage typing and ribotyping performed with PstI and SphI, separately. All methods typed all the strains; however, only ribotyping showed good reproducibility and sensitivity. Twenty-two PS ribotypes (discrimination index = 0.74) were identified, differentiating strains ascribed to seven phage types (PTs 1, 4, 6, 6a, 7, 8 and RDNC) as well as phage untyped strains. Conversely, some strains of PTs, 1, 4, 5a, 6, 6a, 7, 34 and RDNC showed the most frequent PS ribotype. By PCR ribotyping a single profile was found; while by RAPD typing, one, two or three RAPD types were identified with the primers MK22, OPB6 and OPB17, respectively. All Spanish strains were assigned to a single combined RAPD type, except PT11 strains which showed a different and specific RAPD type with OPB17. The banding patterns defining the PS ribotypes were interpreted more easily and the patterns could be compared more accurately than the banding patterns defining RAPD types. A similarity dendrogram generated from the 22 PS ribotypes was traced and compared with RAPD types and phage types. Data from this work indicated that 'PS ribotyping' was the most useful genetic procedure to differentiate Enteritidis strains, and, therefore, it can be used as a complementary or alternative typing method to phage typing within this serotype.

Bacterial Typing Techniques↗