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C G George

Publications and source records attributed to C G George.

10 recordsLinked to original sources
PubMed1999

Methicillin-resistant Staphylococcus aureus outbreak in a veterinary teaching hospital: potential human-to-animal transmission.

During a 13-month period, 11 equine patients visiting a veterinary teaching hospital for various diagnostic and surgical procedures developed postprocedural infections from which methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA) strains were isolated. The S. aureus isolates were identified by conventional methods that included Gram staining, tests for colonial morphology, tests for clumping factor, and tests for coagulase and urease activities and were also tested with the API STAPH IDENT system. Antimicrobial susceptibility tests were performed by the disk diffusion method. The biochemical profile and antibiogram of each isolate suggested that the isolates may have come from a common source. Because MRSA strains are very uncommon animal isolates but are rather common human isolates, a nasal swab specimen for culture was collected voluntarily from five persons associated with equine surgery and recovery in an attempt to identify a possible source of the organisms. MRSA strains were isolated from three of the five people, with one person found to be colonized with two biotypes of MRSA. The MRSA isolates from the people appeared to be identical to the isolates from horses. Further study of the isolates included SmaI and EagI macrorestriction analysis by pulsed-field gel electrophoresis conducted in two different laboratories. The results indicated that both the equine and human isolates were members of a very closely related group which appear to have originated from a common source. On the basis of the pattern associated with the infection, it is speculated that the members of the Veterinary Teaching Hospital staff were the primary source of the infection, although the specific mode of transmission is unclear.

Animals↗
PubMed1998

Staphylococcus hominis subsp. novobiosepticus subsp. nov., a novel trehalose- and N-acetyl-D-glucosamine-negative, novobiocin- and multiple-antibiotic-resistant subspecies isolated from human blood cultures.

A new subspecies, Staphylococcus hominis subsp. novobiosepticus, isolated from human blood cultures, a wound, a breast abscess and a catheter tip, is described on the basis of a study of 26 strains isolated between 1989 and 1996. DNA-DNA reassociation reactions, conducted under stringent conditions, and macrorestriction pattern analysis demonstrated that these strains are closely related to previously characterized S. hominis strains isolated from human skin and clinical specimens, but are significantly divergent. S. hominis subsp. novobiosepticus can be distinguished from S. hominis (now named S. hominis subsp. hominis) by its combined characteristics of novobiocin resistance and failure to produce acid aerobically from D-trehalose and N-acetyl-D-glucosamine. Furthermore, all 26 strains of the new subspecies are resistant to nalidixic acid, penicillin G, oxacillin, kanamycin and streptomycin, and were either resistant or had intermediate resistance to methicillin and gentamicin. Most strains were also resistant to erythromycin, clindamycin, chloramphenicol, trimethoprim/sulfamethoxazole and ciprofloxacin. Based on a comparison of the sequences of a 1001 bp mecA amplification product from reference methicillin-resistant staphylococci, the mecA gene present in S. hominis subsp. novobiosepticus was identified as homologue A, commonly found in S. aureus and many coagulase-negative staphylococcal species. The type strain of S. hominis subsp. novobiosepticus is ATCC 700236T. Descriptions of S. hominis subsp. novobiosepticus subsp. nov and S. hominis subsp. hominis are given and the description of S. hominis is emended.

Acetylglucosamine↗
PubMed1998

Delimiting the genus Staphylococcus through description of Macrococcus caseolyticus gen. nov., comb. nov. and Macrococcus equipercicus sp. nov., and Macrococcus bovicus sp. no. and Macrococcus carouselicus sp. nov.

Four species of the newly proposed genus Macrococcus, namely macrococcus caseolyticus gen. nov., comb. nov. (formerly Staphylococcus caseolyticus Schleifer, Kilpper-Bälz, Fischer, Faller and Endl 1982, 19VP), Macrococcus equipercicus sp. nov., Macrococcus bovicus sp. nov. Macrococcus carouselicus sp. nov., are described on the basis of a phylogenetic analysis comparing 16S rRNA sequences, DNA-DNA liquid hybridization, DNA base composition, normalized ribotype patterns, macrorestriction pattern analysis and estimation of genome size using PFGE, cell wall composition, phenotypic characteristics and plasmid profiles. Compared with their closet relatives, members of the genus Staphylococcus, these organisms demonstrated significantly lower 16S rRNA sequence similarities (93.4-95.3%), higher DNA G+C content (38-45 mol%), absence of cell wall teichoic acids (with the possible exception of M. caseolyticus), unique ribotype pattern types and macrorestriction patterns, smaller genome size (approx. 1500-1800 kb) and generally larger Gram-stained cell size (1.1-2.5% microns in diameter). Macrococci can be distinguished from most species of staphylococci (except Staphylococcus sciuri, Staphylococcus vitulus and Staphylococcus lentus) by thier oxidase activity. The four Macrococcus species can be distinguished from one another on the basis of DNA-DNA hybridization, ribotype pattern types, macrorestriction patterns and their phenotypic properties, including colony morphology, cell morphology, haemolysins, Staphy Latex agglutination, acid production from a variety of carbohydrates, acetoin production, nitrate reduction, aesculin hydrolysis, and DNase and urease activities. The type species is M. equipercicus. The type strains of M. equipercicus, M. caseolyticus, M. bovicus and M. carouselicus are ATTCC 51831T (= DD 9350T) ATCC 13548T (= TDD 4508T) (Schleifer et al. 1982, ATCC 51825T (= DD 4516T) and ATCC 51828T (= DD 9348), respectively.

Animals↗
PubMed1997

Identification of Staphylococcus species and subspecies by the chaperonin 60 gene identification method and reverse checkerboard hybridization.

A previous study (S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996) demonstrated that a 600-bp region of the chaperonin 60 (Cpn60) genes from various bacterial isolates could be amplified by PCR with a pair of degenerate primers and that the products could be used as species-specific probes for Staphylococcus aureus, S. epidermidis, S. haemolyticus, S. lugdunensis, S. saprophyticus, and S. schleiferi. To further validate the utility of bacterial Cpn60 genes as universal targets for bacterial identification (ID), reverse checkerboard chemiluminescent hybridization experiments were performed with DNA probes from 34 different Staphylococcus species and subspecies. With the exception of probes from the Cpn60 genes of S. intermedius and S. delphini, which cross hybridized, all were species specific. Two subspecies of both S. capitis and S. cohnii were differentiated from one another, while DNAs from the two S. schleiferi subspecies cross hybridized. When 40 known Staphylococcus isolates were tested in a blind experiment by the Cpn60 gene method, 36 strains, representing six species and one subspecies (S. sciuri, S. caseolyticus, S. hominis, S. warneri, S. hyicus, S. haemolyticus, and S. capitis subsp. ureolyticus), were correctly identified. DNA from the four remaining isolates, known to be S. hyicus bovine strains, failed to hybridize to DNA from the S. hyicus target strain or any other Staphylococcus species. However, DNAs from these S. hyicus isolates did cross hybridize with each other. New DNA sequence data and evidence from previous studies suggest some genetic divergence between the two groups of S. hyicus isolates. Our results demonstrate that this Cpn60 gene-based ID method has the potential to be a basic method for bacterial ID. Studies are in progress to further validate the utility of this Cpn60 gene system for ID of Staphylococcus and other genera, including those of slow-growing microorganisms.

Animals↗
PubMed1997

Pulsed-field gel electrophoresis of Staphylococcus hyicus and Staphylococcus chromogenes genomic DNA and its taxonomic, epidemiologic and ecologic applications in veterinary medicine.

One hundred and thirty-eight strains of Staphylococcus hyicus and 21 strains of S. chromogenes isolated from animals were analyzed by pulsed-field gel electrophoresis (PFGE) after restriction endonuclease Smal digestion of chromosomal DNA. Eighty-eight strains of S. hyicus from pigs with or without exudative epidermitis (EE) generated 16 to 26 fragments in the size range of < 1 to 485 kb, and yielded 39 different patterns. With regard to the strains from pigs with EE, PFGE patterns differed according to the country of origin. Outbreaks of EE occurring on four separate pig farms in Japan involved S. hyicus with different PFGE patterns. The PFGE patterns shown by S. hyicus strains from 4 kinds of animals were compared. Strains from pigs differed from those isolated from chickens (n = 45; 18 to 24 fragments of < 1 to 425 kb), cows (n = 3; 17 to 19 fragments of < 1 to 475 kb), and goats (n = 2; 16 or 17 fragments of < 1 to 1,125 kb). Also, each of the chicken, cow and goat strains had a host-specific fragment. The results suggest that PFGE analysis might be a useful marker for distinguishing ecovars within S. hyicus. In contrast, strains of S. chromogenes from pigs and cows generated 17 to 24 fragments ranging from < 1 to 545 kb. The PFGE patterns of S. chromogenes strains were more highly conserved than those of S. hyicus. S. chromogenes strains could be distinguished from S. hyicus strains by fragments within the range of 305 to 545 kb. The results indicate that PFGE analysis could be used to distinguish between S. hyicus and S. chromogenes. We conclude that PFGE analysis is a useful tool not only for species or strain identification but also for epidemiologic or ecologic studies of S. hyicus and S. chromogenes.

Animals↗
PubMed1996

Genomic DNA fingerprinting, using pulsed-field gel electrophoresis, of Staphylococcus intermedius isolated from dogs.

OBJECTIVES: To investigate the degree of polymorphism in the pulsed-field gel electrophoresis (PFGE) patterns of Staphylococcus intermedius and to assess the value of this typing method for discriminating strains. SAMPLE POPULATION: 52 S intermedius isolates from diseased and healthy dogs. PROCEDURE: Chromosomal DNA of S intermedius was digested with restriction endonuclease Sma I, and the fragments were separated by PFGE in a 1% agarose gel. RESULTS: Sma I cut the chromosomal DNA into 15 to 23 fragments ranging from about < 1 to 679 kb, and most of the detectable fragments were < 155 kb. Nine fragments, 115, 48, 33, 26, 16, 13, 10, 4, and < 1 kb, were shared by all or almost all (> 71%) of the strains examined. Of the 52 strains, each had a different pattern. S intermedius had a high degree of restriction fragment length polymorphism. The PFGE patterns obtained for S intermedius were stable and reproducible when the strains were tested in the different experiments. CONCLUSIONS: Genomic DNA fingerprinting by PFGE is an effective technique for discriminating S intermedius strains. The PFGE method appears to be a useful molecular marker for epidemiologic or ecologic studies of S intermedius.

Animals↗
PubMed1994

Comparison of the SmaI-digested chromosomes of Staphylococcus epidermidis and the closely related species Staphylococcus capitis and Staphylococcus caprae.

Pulsed-field gel electrophoresis was used to examine the chromosomal polymorphisms existing within and between four closely related members of the Staphylococcus epidermidis species group, S. epidermidis, Staphylococcus caprae, Staphylococcus capitis subsp. capitis, and S. capitis subsp. ureolyticus. SmaI was chosen as the restriction endonuclease for this study because it generated only a few well-separated chromosomal fragments. Each of the species and subspecies showed distinct SmaI digest patterns. The strains examined in this study were collected over a 20-year period from various geographical locations. The results indicate that DNA fragment patterns are unique to each species and subspecies and represent a reasonably stable component in the chromosome structure. S. caprae and S. capitis demonstrated considerable conservation in chromosome structure as indicated by the large numbers of conserved SmaI digest fragments. The polymorphisms found within each species appear to be linked to the species' character variability. The genome size of each Staphylococcus strain was extrapolated from the SmaI digest fragment pattern obtained by pulsed-field gel electrophoresis. The average genome size for S. epidermidis is 2,364 +/- 119 kb; for S. caprae strains from humans it is 2,600 +/- 157 kb and for S. caprae strains from goats it is 2,493 +/- 15 kb; for S. capitis subsp. capitis it is 2,456 +/- 71 kb; and for S. capitis subsp. ureolyticus it is 2,276 +/- 90 kb.

Animals↗
PubMed1991

Selection of colony, plasmid, and virulence variants of Staphylococcus epidermidis NRC853 during growth in continuous cultures exposed to erythromycin.

A continuous-culture system was developed to study changes in the structure of Staphylococcus epidermidis populations exposed to subminimum inhibitory concentrations of erythromycin. Continuous-culture experiments were carried out in a dextrose-free, tryptic soy broth medium supplemented with lactic acid and sodium lactate (MTSB-D). The multiresistant (penicillin-, tetracycline-, and erythromycin-resistant) S. epidermidis strain NRC853 was subjected to a series of experiments: (i) growth individually in continuous culture in the absence and presence of erythromycin and (ii) growth in mixed culture with the erythromycin-susceptible S. epidermidis strain NRC852 in the absence and presence of erythromycin. Strain NRC853 produced colony morphology variants during continuous culture in the presence of 0.05 and 0.1 microgram of erythromycin per ml. Variants (A, B, and C) were different from their wild-type parent on the basis of colony size, sector pattern, and/or the ability to transmit light. A variants rapidly lost a 2.7-MDa tetracycline resistance plasmid. B and C variants formed an ermC plasmid multimer series from unit size to a 16-mer and exhibited an approximately twofold increase in erythromycin MIC over that of the wild-type parent. They slowly lost the tetracycline resistance plasmid. The small-colony B variant demonstrated an increased virulence in the neonatal mouse weight gain test and an increase in fibronectin binding compared with the wild-type parent. The presence of a competing strain drastically increased the frequency of all variants.

Animals↗
PubMed1991

Identification of Staphylococcus species and subspecies with the MicroScan Pos ID and Rapid Pos ID panel systems.

The accuracies of the MicroScan Pos ID and Rapid Pos ID panel systems (Baxter Diagnostic Inc., MicroScan Division, West Sacramento, Calif.) were compared with each other and with the accuracies of conventional methods for the identification of 25 Staphylococcus species and 4 subspecies. Conventional methods included those used in the original descriptions of species and subspecies and DNA-DNA hybridization. The Pos ID panel uses a battery of 18 tests, and the Rapid Pos ID panel uses a battery of 42 tests for the identification of Staphylococcus species. The Pos ID panel has modified conventional and chromogenic tests that can be read after 15 to 48 h of incubation; the Rapid Pos ID panel has tests that use fluorogenic substrates or fluorometric indicators, and test results can be read after 2 h of incubation in the autoSCAN-W/A. Results indicated that both MicroScan systems had a high degree of congruence (greater than or equal to 90%) with conventional methods for the species S. capitis, S. aureus, S. auricularis, S. saprophyticus, S. cohnii, S. arlettae, S. carnosus, S. lentus, and S. sciuri and, in particular, the subspecies S. capitis subsp. capitis and S. cohnii subsp. cohnii. The Rapid Pos ID panel system also had greater than or equal to 90% congruence with conventional methods for S. epidermidis, S. caprae, S. warneri subsp. 2, S. xylosus, S. kloosii, and S. caseolyticus. For both MicroScan systems, congruence with conventional methods was 80 to 90% for S. haemolyticus subsp. 1, S. equorum, S. intermedius, and S. hyicus; and in addition, with the Rapid Pos ID panel system congruence was 80 to 89% for S. capitis subsp. ureolyticus, S. warneri subsp. 1, S. hominis, S. cohnii subsp. urealyticum, and S. simulans. The MicroScan systems identified a lower percentage (50 to 75%) of strains of S. lugdunensis, S. gallinarum, S. schleiferi, and S. chromogenes, although the addition of specific tests to the systems might increase the accuracy of identification significantly.

Autoanalysis↗