Showing papers on "Typing published in 1987"

A phage-typing scheme for Salmonella enteritidis.

Abstract: For many years phage typing has proved invaluable in epidemiological studies on Salmonella typhi, S. paratyphi A and B, S. typhimurium and a few other serotypes. A phage-typing scheme for S. enteritidis is described. This scheme to date differentiates 27 types using 10 typing phages.

Molecular epidemiology of Legionella species by restriction endonuclease and alloenzyme analysis.

Abstract: As part of an ongoing investigation into nosocomial Legionella infections at Stanford University Medical Center (SUMC), we applied the technique of restriction endonuclease analysis (REA) to determine strain differences among three species, including Legionella pneumophila, Legionella dumoffii, and Legionella micdadei. A total of 26 human and environmental water isolates from SUMC were selected for REA and compared with control strains that were not epidemiologically linked to SUMC. REA results were compared with results of alloenzyme typing, typing by monoclonal antibodies, and plasmid fingerprinting in all but L. micdadei strains. REA and alloenzyme typing showed that SUMC patient isolates were derived from distinct strains of three species. L. pneumophila strains from SUMC patients were genotypically identical to those isolated from potable water. REA was especially useful in proving that SUMC L. dumoffii patient isolates were derived from a single strain and that patients may have been exposed to a common source(s). REA typing correlated well with alloenzyme typing. These methods complement serologic typing of L. pneumophila and provide discriminating capability between strains of other Legionella species such as L. dumoffii, for which serologic types have not been identified. In addition, REA typing is somewhat easier to perform than alloenzyme typing and can be done in clinical laboratories. Images

Restriction endonuclease DNA analysis of Clostridium difficile.

Abstract: HindIII restriction enzyme digests of genomic DNA from nine distinct strains of Clostridium difficile were undertaken, and the results were related to those of a previously established typing method based on [35S]methionine-labeled protein profiles. Each of the typed strains identified by its protein profile could also be distinguished by its unique DNA digestion pattern. Analysis of strains isolated from 10 patients during a hospital outbreak of antibiotic-associated colitis revealed identical DNA profiles, confirming a single strain as the source of cross-infection. Characterization of isolates from worldwide sources revealed similar digestion patterns within the same strain type. Restriction endonuclease DNA analysis provides a sensitive and useful technique for studying the epidemiology of C. difficile.

Identification of HLA-DP polymorphism with DP alpha and DP beta probes and monoclonal antibodies: correlation with primed lymphocyte typing.

Abstract: Thirty-four lymphoblastoid cell lines that had been previously typed for HLA-DP antigens by primed lymphocyte typing (PLT) were tested by Southern blotting and by ELISA. Using two DP beta probes and a DP alpha probe with a series of enzymes, it is possible to identify restriction fragment length polymorphism (RFLP) patterns characteristic of DPw1, -2, -3, -4, and possibly -5. ELISA typing results, based on two polymorphic DP antibodies DP11.1 and ILR1, were compared with PLT-defined and RFLP-defined types. Thus, using a range of probes and enzymes it is possible to identify DP polymorphism. The value of monoclonal antibodies for such studies is demonstrated, and the molecular data can, in some cases, pinpoint the amino acids responsible for the specificity of the monoclonal antibodies.

Staphylococcal whole-cell polypeptide analysis: evaluation as a taxonomic and typing tool.

Abstract: Whole-cell-polypeptide profiles obtained by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) were used in conjunction with the API-Staph technique to identify different strains of Staphylococcus aureus, S epidermidis, S saprophyticus and S capitis Complete concordance of results from both techniques was achieved with all strains examined Visual analysis of the polypeptide patterns and comparison by use of the coefficient of Dice showed minor differences in band pattern between strains of the same species but each species produced a pattern distinguishable from that of any other The results suggest that although SDS-PAGE can be used to identify staphylococcal species, this type of analysis will not readily provide the basis for a typing method

Monoclonal antibody typing of Chlamydia psittaci strains derived from avian and mammalian species.

Abstract: A total of 77 Chlamydia psittaci strains of avian, human, and mammalian origin were grouped into four serovars with 11 monoclonal antibodies recognizing the lipopolysaccharide and the major outer membrane protein antigens. The avian and human strains, which were closely related to each other, were distinct from the mammalian strains. Immunological typing of C. psittaci with monoclonal antibodies seems practical.

New bacteriophage typing scheme for subdivision of the frequent capsular serotypes of Klebsiella spp.

Abstract: A bacteriophage typing scheme for hospital isolates of Klebsiella spp. was developed. The scheme was designed specifically as a secondary typing method to discriminate between strains of serotypes K2, K3, and K21 but proved to be an efficient general typing method for strains of most serotypes. The set of 15 phages gave 87.3% typeability on 236 strains of more than 70 different serotypes. Typeability within the K2, K3, and K21 strains was 93, 89, and 91%, respectively. There was a mean of 3.2 reactions strain-1 for all phage-typeable strains. Of the serologically nontypeable strains, 76.7% were susceptible to one or more phages. The most common pattern accounted for only 7% of the strains. The lytic patterns were reproducible if strains were typed on the same day, but differences were observed if strains were stored for 1 week or more before retyping. A total of 96.5% of the strains were typeable by a combination of capsular serology and phage typing.

Application of chromosomal restriction endonuclease digest analysis for use as typing method for Clostridium difficile.

Abstract: The usefulness of restriction endonuclease analysis of chromosomal DNA as a typing method for Clostridium difficile was tested. Over four months all faecal samples were routinely cultured for C difficile. DNA of all isolated strains was isolated and tested with the restriction endonuclease Hind III. The patterns obtained after electrophoresis in agarose gels seemed to be strain specific. Antibiotic susceptibility profiles agreed with the results of the restriction endonuclease analysis, though they were much less discriminating. Analysis of the results indicated that restriction endonuclease analysis is a suitable typing method for C difficile, which may be very valuable in epidemiological studies where a highly discriminating typing method is needed.

Optimizing a Portable Terminal Keyboard for Combined One-Handed and Two-Handed use

Abstract: Human factors experimentation facilitated the design of a portable terminal keyboard for combined one-handed and two-handed operation. To ensure a comfortable grip, the terminal had to be made smaller by reducing the size of its keyboard. The product design team needed to know how small the keyboard could be before it degraded the usability of the keyboard and the overall product. The keyboard experiment was designed primarily to determine the effect of both the number of hands used in typing and key spacing on typing speed and accuracy. A total of six commercially available keyboards with key spacings varying from 0.75 to 0.45 inches were tested. Test subjects with typing skills ranging from expert to novice typed separate samples of text on each keyboard, once using one hand and once using two hands. The difference in typing speed between two and one-handed typing averaged 2—1. A key spacing less than about 0.7 inches substantially reduced typing speed but did not increase errors. Poor typists typed at ...

Analysis of HLA-D micropolymorphism by a simple procedure: RNA oligonucleotide hybridization.

Abstract: Recent progress in the molecular genetics of HLA class II antigens has revealed the existence of multiple loci and of a large degree of polymorphism, with more individual alleles than was expected. An accurate detection and analysis of this extensive polymorphism is essential for optimal HLA typing for transplantation and for a reevaluation of HLA-disease association. Because of the limitations of the current typing methods, including restriction fragment length polymorphisms, we have proposed a DNA typing procedure based on hybridization with loci- and allele-specific oligonucleotides. Here we present a much simpler way of analyzing class II micropolymorphism down to the level of single nucleotide differences. RNA oligonucleotide typing (ROT) relies on RNA dot blots and requires 10-20 ml of blood. It is shown that with appropriate oligonucleotide probes, ROT can reliably and unambiguously identify any polymorphism at any of the HLA loci, including new alleles, not identified with previous methods. This illustrates the importance of oligonucleotide typing to optimize HLA matching, in particular for transplantation involving unrelated donors.

Evaluation of a bacteriophage-typing scheme for Enterobacter cloacae.

Abstract: A set of 25 Enterobacter cloacae typing phages was evaluated. Of 384 test strains, 93.8% were lysed by at least one phage; the mean number of reactions/strain was 7.3. Discrimination between strains was satisfactory within the most frequent O serotypes; 0.9 patterns/strain were found for strains of serotypes O3 and O8. Overall, 325 patterns were found. Phage patterns were completely reproducible when duplicates of strains were typed on the same day, but only 40% reproducible when repeated after 18 months. The combination of O serology and phage typing discriminated well between hospital isolates.

Combined use of phage typing, enterococcinotyping and species differentiation of group D streptococci as an effective epidemiological tool.

Abstract: Summary Ninety-five group D streptococcal isolates from the feces of 95 healthy persons were compared with 157 group D streptococcal isolates from 38 patients of the surgical intensive care unit (sICU). The typing systems consisted of phage typing, enterococcinotyping and species differentiation. Strains isolated from fecal specimens showed high individuality (66 combination types) whereas strains from the sICU revealed strongly uniform types (32 combination types, three types comprised 83 isolates, i.e. 52.8%). Endogenous colonization was demonstrated by isolation of strains from different locations (throat, trachea, wounds, blood, urine, drains, catheters, and vaginal swabs) from the same patient, and. routes of transmission of the same strains to several patients were traced. The combination of three systems revealed a good discrimination between isolates of fecal and extrafecal specimens. The investigation detected highly preferred types in strains of extrafecal origin which were rarely isolated from fecal specimens. This may indicate that only strains with special characters preferably were able to colonize extraintestinal sites.

Evaluation of three immunofluorescence assays for culture confirmation and typing of herpes simplex virus.

Abstract: Three pairs of monoclonal antibodies, supplied in kits by Electro-Nucleonics, Inc. (ENI), The Syva Co., and Kallestad Laboratories, Inc. (KL), were evaluated for the laboratory confirmation and typing of herpes simplex virus (HSV). Of 108 coded HSV slide preparation, run in parallel with each monoclonal-antibody set, 103 were equivalent by the immunofluorescence assays. Among the five discordant isolates, three (2.8%) did not type with the KL monoclonal antibodies and two (1.9%) false-positive results occurred with the Syva typing system. All of the HSV clinical isolates tested were correctly typed with the ENI indirect immunofluorescence antigen detection system. Typing confirmation of the five discordant HSV isolates was performed by differential sensitivity to 5-bromo-2'-deoxyuridine and endonuclease cleavage analysis of the viral DNA. Use of the Syva and KL direct immunofluorescence antigen detection systems for the identification of HSV isolates is less time-consuming than use of the ENI indirect antigen detection system; however, sensitivity and specificity may be lost.

Relationship of bacteriocin-like inhibitor production to the pigmentation and hemolytic activity of mutans streptococci.

Abstract: Summary An inhibitor production typing (P-typing) scheme originally devised for hemolytic streptococci of Lancefield groups A-G has been successfully applied to 35 mutans streptococcus isolates recovered from plaque cultures of 60 Dunedin schoolchildren. Thirteen different P-type designations were identified. Although 11 (31%) of the isolates failed to produce detectable inhibitory activity on the conventional blood agar medium used for P-typing, four of these isolates were inhibitor-positive on Trypticase Soy agar supplemented with 2% yeast extract and 0.5% calcium carbonate (TSYCa). Four mutans strains displayed strong s-hemolysis on Columbia agar base containing human blood when incubated in a 5% CO2 in air atmosphere. Three of these also produced weak β-hemolysis on sheep blood-supplemented medium and were further distinctive in that they were the only inhibitor P-type 767 strains to be detected in the present study. Five mutans isolates were pigment producers and this property seemed to occur independently of both the β-hemolytic activity and the P-type designation. Upon testing an additional collection of 18 mutans strains of various serotypes, only seven (39%) were inhibitor-positive. However, three of the four serotype c strains were inhibitor producers. Two strains of serotype d and one of serotype g were more hemolytic on sheep than on human blood agar medium. In general, it seems that the most common human mutans streptococci (serotype c strains) are more likely than are other mutans strains to produce bacteriocin-like inhibitory activity and to be hemolytic for human rather than sheep erythrocytes.

Molecular relatedness of staphylococcus aureus typing phages measured by DNA hybridization and by high resolution thermal denaturation analysis

Abstract: Fifteen bacteriophages representative of the serological and lytic groups of the International Typing Set forStaphylococcus aureus were examined for genomic homology by DNA hybridization and by analysis of high resolution thermal denaturation profiles. Phages 11 and 80 α, not part of the set, were also examined.

Current status of Pseudomonas cepacia typing systems.

Abstract: Pseudomonas cepacia is an important nosocomial pathogen for which measures of isolate relatedness are being developed. Typing systems based on 4 different strain characteristics have been proposed: serologic reactions, biochemical reactions, plasmid profiles, and bacteriocin production and susceptibility. Serology and bacteriocins distinguish many types, but the sensitivity and specificity of these techniques have not been determined. Improved methods for typing P. cepacia are needed to determine the reservoirs and modes of transmission of this emerging nosocomial pathogen.

Multivariate analysis of antibiograms for typing Pseudomonas aeruginosa.

Abstract: A method for typing Pseudomonas aeruginosa using antibiotic susceptibility patterns is presented, which allows recognition of clusters of the same strain among clinical isolates from different patients, thus indicating whether cross infection has occurred. An index of similarity (the euclidean or the oblique distance), which includes all the differences of disk zone sizes among isolates, is computed and then elaborated by a clustering algorithm that successively groups all the isolates in larger clusters. The results of clustering are presented as dendrograms, whose terminal branches are pruned down to a level below which differences are casual; isolates that still appear on a common branch are considered identical. The reliability of this technique for detecting nosocomial cross infections was assessed by comparing its results with that of serotyping and pyocin typing. Only 2 of 31 (6.4%) clusters detected by multivariate analysis were not confirmed, while 4 of 33 (12.1%) clusters were recognized by serotyping and pyocin typing, but not by multivariate analysis. In at least two instances the differences in susceptibility patterns were due to cytoplasmic R factors. The routine use of antibiogram data for typing purposes should be considered an essential part of nosocomial infection control.

A new scheme for phage typing Salmonella bareilly and characterization of typing phages.

Abstract: A new phage typing scheme using wild bacteriophages isolated from sewage for phage typing Salmonella bareilly is described. Six hundred and thirty-seven strains of Salm. bareilly could be separated into 11 different phage types using five wild phages. Overall typability was 94.5%. These phages belonged to two different morphotypes. A1 and B1, and showed varying host range.

Multiply- and methicillin-resistant Staphylococcus aureus strains isolated in the German Democratic Republic in 1985 and 1986.

Abstract: Multiply- and methicillin-resistant Staphylococcus aureus (MRSA) strains have been isolated from five small outbreaks of nosocomial infection in five different hospitals. The MRSA were typed by phage patterns, biochemical traits, resistance phenotypes and plasmid patterns. Three different groups of strains can be distinguished. The MRSA from three outbreaks in one country share identical characters. Phage typing by the use of the International Basic Set for Phage Typing staphylococci as well as experimental phages does not completely discriminate between the strains. Attribution of several resistance determinants to plasmids in two of the described strain groups proved valuable for strain differentiation. These multiply-resistant strains are sensitive to vancomycin and to rifampicin.

Staphylococcus aureus strains of the 94/96 complex isolated in the German Democratic Republic: Incidence and discrimination of strain clones

Abstract: Summary The incidence of S aureus with a phage pattern of 94/96 rose from 9% in 1979 to 18% in 1985 The frequency of occurrence not only increased among isolates from inpatients and outpatients but also among those from healthy carriers All of the 504 investigated strains of different origin exhibited a uniform pattern of biochemical characteristics In each of 40 investigated strains, a plasmid with a molecular mass of 16 Md was found Elimination experiments indicated that these plasmids determined resistance to penicillin and/or cadmium Resistance to chloramphenicol was found to be determined by plasmids of 20 Md, resistance to Oxytetracycline by plasmids of 27 Md Clones could be discriminated by means of 7 experimental phages The application of these phages for typing strains from infections in hospitals is demonstrated

DNA typing of HLA-DR beta chain genes can discriminate between undetected alleles and real homozygotes.

Abstract: The polymorphism of HLA-DR antigens has been studied by Southern blot hybridization under conditions specific for the detection of the DR β chain genes. Haplotype-specific patterns were defined with DNA from DR1, 2, 3, 4, 7, w8, w11, w12, and W13 homozygous typing cells, with restriction enzymes Eco RI, Bgl I, and Pvu II. Certain serological specificities, such as DR2, DR3, and DR7, can be encoded by distinct allelic forms of DR β chain genes. The procedure of “DNA typing” was applied to family analysis of individuals expressing only a single DR specificity upon serological typing. Three cases are described here: (1) in family GR, phenotypic DR 7 homozygotes correspond to genomic heterozygotes, and a novel DR7 allele is described: (2) in family RU, the genes corresponding to a serologically undetected (blank) DR allele were identified by restriction fragment length polymorphism (RFLP); this novel DR haplotype has an RFLP pattern similar to those of the DRw52 family, even though this specificity was not expressed on the DR-blank lymphocytes; (3) in family RG, there is no blank allele, but a homozygote RFLP situation at the DR subregion.

NewBacteriophage Typing SchemeforSubdivision oftheFrequent Capsular Serotypes ofKlebsiella spp.

Abstract: A bacteriophage typing schemeforhospital isolates ofKlebsiella spp.was developed. Theschemewas designed specifically asa secondary typing methodtodiscriminate between strains ofserotypes K2,K3,and K21butproved tobeanefficient general typing methodforstrains ofmostserotypes. Thesetof15phages gave 87.3%typeability on 236strains ofmore than70different serotypes. Typeability within theK2,K3,andK21 strains was 93,89,and91%,respectively. There was a mean of3.2reactions strain'1 forall phage-typeable strains. Oftheserologically nontypeable strains, 76.7%were susceptible toone or morephages. Themost common pattern accounted foronly7% ofthestrains. Thelytic patterns werereproducible ifstrains were typed onthesame day, butdifferences wereobserved ifstrains werestored for1weekormore before retyping. A total of96.5%ofthestrains weretypeable byacombination ofcapsular serology andphagetyping.

Comparison of biochemical and serological typing results and antimicrobial susceptibility patterns in the epidemiological investigation of Klebsiella spp.

Abstract: An analysis of the serological and biochemical typing results of 925 clinical isolates of klebsiella revealed that biotyping and serotyping of klebsiella could replace each other for epidemiological purposes. The combination of both typing methods provided even more epidemiological information in analysing clusters of particular serotypes and biotypes in time. Clustering serotypes, mainly of neonatal origin, were nearly uniformly more resistant to the antibiotics in common use than other serotypes. Biotyping as well as serotyping of klebsiella isolates recovered from environmental surveys in the neonatal ward showed that epidemic and non-epidemic klebsiella isolates could occasionally be cultured from the environment and from the staff.