Biomedical subjects

Kari S Gobius

Publications and source records attributed to Kari S Gobius.

6 recordsLinked to original sources

PubMed2006

Diverse class 2 integrons in bacteria from beef cattle sources.

OBJECTIVES: The purpose of this study was to determine the diversity of class 2 integrons in bacteria isolated from beef cattle sources. METHODS: The variable regions of a subset of 11 class 2 integron-containing bacteria were analysed by PCR and DNA sequencing for the presence of novel rearrangements. RESULTS: A total of six different class 2 integron arrays were identified and four of these were fully characterized. Three of the four arrays characterized have been previously described; however the remaining array is unlike previously described class 2 integrons. The novel class 2 integron was found in Providencia stuartii and contains an apparently functional class 2 integrase. Examination of the variable region of the P. stuartii integron identified nine open reading frames, mostly of unknown function, and represents the first report of a class 2 integron without inserted antibiotic resistance gene cassettes. CONCLUSIONS: This study has identified a novel class 2 integron found in P. stuartii that contains an apparently functional naturally occurring class 2 integrase. Further investigation of this novel class 2 integron is required to determine the impact of a functional class 2 integrase upon the evolution of class 2 integrons.

Animals↗

PubMed2006

Shiga toxin-producing Escherichia coli in ground beef and lamb cuts: results of a one-year study.

Shiga toxin-producing Escherichia coli (STEC) have been associated with a broad spectrum of diarrhoeal syndromes. Some of these cases have been attributed to foods of bovine origin or other foods cross-contaminated by beef products or cow manure. The purpose of this study was to determine the pattern of STEC distribution in selected red meats over time. Samples of ground beef and lamb cuts were collected over a 52-week period from 31 different outlets and 25 g portions were assayed for STEC. STEC were isolated from 46/285 (16%) ground beef and 111/275 (40%) lamb samples using an stx PCR screen followed by colony hybridisation. All isolates were tested by PCR for additional STEC virulence markers with 95% of ground beef isolates shown to possess stx(2) and 80% of lamb cutlet isolates shown to possess stx(1) and stx(2). The enterohaemolysin gene (ehxA) was detected in 65% and 53% of ground beef and lamb isolates respectively. Putative enterohaemorrhagic E. coli (EHEC), i.e. STEC possessing the E. coli attaching and effacing gene (eae) were not isolated. The STEC isolates comprised 18 and 15 different serotypes from ground beef and lamb respectively. STEC of serotypes O157, O111 and O26 (common enterohaemorrhagic E. coli serotypes) were not isolated. Serotypes O174 and O91 were the most common serotypes isolated from ground beef samples and O128 and O91 the most common from lamb cutlet samples. The presence of STEC in retail red meats highlights the need for a clearer understanding of STEC in food and human illness to interpret the public health significance of these findings.

Adhesins, Bacterial↗

PubMed2006

Identification of bla(CMY-7) and associated plasmid-mediated resistance genes in multidrug-resistant Escherichia coli isolated from dogs at a veterinary teaching hospital in Australia.

OBJECTIVES: To determine clonality and identify plasmid-mediated resistance genes in 11 multidrug-resistant Escherichia coli (MDREC) isolates associated with opportunistic infections in hospitalized dogs in Australia. METHODS: Phenotypic (MIC determinations, modified double-disc diffusion and isoelectric focusing) and genotypic methods (PFGE, plasmid analysis, PCR, sequencing, Southern hybridization, bacterial conjugation and transformation) were used to characterize, investigate the genetic relatedness of, and identify selected plasmid-mediated antimicrobial resistance genes, in the canine MDREC. RESULTS: Canine MDRECs were divided into two clonal groups (CG 1 and 2) with distinct restriction endonuclease digestion and plasmid profiles. All isolates possessed bla(CMY-7) on an approximately 93 kb plasmid. In CG 1 isolates, bla(TEM), catA1 and class 1 integron-associated dfrA17-aadA5 genes were located on an approximately 170 kb plasmid. In CG 2 isolates, a second approximately 93 kb plasmid contained bla(TEM) and unidentified class 1 integron genes, although a single CG 2 strain carried dfrA5. Antimicrobial susceptibility profiling of E. coli K12 transformed with CG 2 large plasmids confirmed that the bla(CMY-7)-carrying plasmid did not carry any other antimicrobial resistance genes, whereas the bla(TEM)/class 1 integron-carrying plasmid carried genes conferring resistance to tetracycline and streptomycin also. CONCLUSIONS: This is the first report on the detection of plasmid-mediated bla(CMY-7) in animal isolates in Australia. MDREC isolated from extraintestinal infections in dogs may be an important reservoir of plasmid-mediated resistance genes.

Animals↗

PubMed2006

Emergence and spread of two distinct clonal groups of multidrug-resistant Escherichia coli in a veterinary teaching hospital in Australia.

Multidrug-resistant Escherichia coli (MDREC) expressing AmpC beta-lactamases have emerged as a cause of opportunistic infections in dogs. Following a cluster of extraintestinal infections caused by two distinct clonal groups (CGs) of bla(CMY)-producing MDREC, a 12-month infection control study was undertaken at a veterinary teaching hospital in Brisbane, Australia. Swabs from the rectum of hospitalized dogs (n=780), hospital staff (n=16) and the hospital environment (n=220) were plated onto selective agar to obtain multidrug-resistant (MDR) coliforms. These were then tested by multiplex PCR for E. coli uspA, bla(CMY) and the class 1 integron-associated dfrA17-aadA5 gene cassette for rapid identification of MDREC CG 1 (positive for all three genes) and CG 2 (positive for uspA and bla(CMY) only). A total of 16.5 % of the dog rectal swabs and 4.1% of the hospital environmental swabs yielded MDREC, and on the basis of multiplex PCR, PFGE and plasmid profiling, these were confirmed to belong to either CG 1 or CG 2. Both CG 1 and CG 2 isolates were obtained from clinical cases of extraintestinal infection and rectal swabs from hospitalized dogs over the same period of time, whereas only CG 1 isolates were obtained from the hospital environment. Both CGs were prevalent during the first 6 months, but only CG 2 was isolated during the second 6 months of the study. Two isolates obtained from rectal swabs of staff working in the hospital belonged to CG 2, with one of the isolates possessing the same REDP as nine isolates from dogs, including six isolates associated with cases of extraintestinal infection. CG 1 isolates belonged to E. coli serotypes O162 : H-, OR : H- or Ont : H-, whereas CG 2 isolates belonged to O153 : HR, OR : HR or OR : H34. These results confirm that in this particular outbreak, canine MDREC were highly clonal and CG 2 MDREC may colonize both humans and dogs.

Animals↗

PubMed2004

Isolation and characterization of integron-containing bacteria without antibiotic selection.

The emergence of antibiotic resistance among pathogenic and commensal bacteria has become a serious problem worldwide. The use and overuse of antibiotics in a number of settings are contributing to the development of antibiotic-resistant microorganisms. The class 1 and 2 integrase genes (intI1 and intI2, respectively) were identified in mixed bacterial cultures enriched from bovine feces by growth in buffered peptone water (BPW) followed by integrase-specific PCR. Integrase-positive bacterial colonies from the enrichment cultures were then isolated by using hydrophobic grid membrane filters and integrase-specific gene probes. Bacterial clones isolated by this technique were then confirmed to carry integrons by further testing by PCR and DNA sequencing. Integron-associated antibiotic resistance genes were detected in bacteria such as Escherichia coli, Aeromonas spp., Proteus spp., Morganella morganii, Shewanella spp., and urea-positive Providencia stuartii isolates from bovine fecal samples without the use of selective enrichment media containing antibiotics. Streptomycin and trimethoprim resistance were commonly associated with integrons. The advantages conferred by this methodology are that a wide variety of integron-containing bacteria may be simultaneously cultured in BPW enrichments and culture biases due to antibiotic selection can be avoided. Rapid and efficient identification, isolation, and characterization of antibiotic resistance-associated integrons are possible by this protocol. These methods will facilitate greater understanding of the factors that contribute to the presence and transfer of integron-associated antibiotic resistance genes in bacterial isolates from red meat production animals.

Animals↗

PubMed2003

Presence of activatable Shiga toxin genotype (stx(2d)) in Shiga toxigenic Escherichia coli from livestock sources.

Stx2d is a recently described Shiga toxin whose cytotoxicity is activated 10- to 1000-fold by the elastase present in mouse or human intestinal mucus. We examined Shiga toxigenic Escherichia coli (STEC) strains isolated from food and livestock sources for the presence of activatable stx(2d). The stx(2) operons of STEC were first analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis and categorized as stx(2), stx(2c vha), stx(2c vhb), or stx(2d EH250). Subsequently, the stx(2c vha) and stx(2c vhb) operons were screened for the absence of a PstI site in the stx(2A) subunit gene, a restriction site polymorphism which is a predictive indicator for the stx(2d) (activatable) genotype. Twelve STEC isolates carrying putative stx(2d) operons were identified, and nucleotide sequencing was used to confirm the identification of these operons as stx(2d). The complete nucleotide sequences of seven representative stx(2d) operons were determined. Shiga toxin expression in stx(2d) isolates was confirmed by immunoblotting. stx(2d) isolates were induced for the production of bacteriophages carrying stx. Two isolates were able to produce bacteriophages phi1662a and phi1720a carrying the stx(2d) operons. RFLP analysis of bacteriophage genomic DNA revealed that phi1662a and phi1720a were highly related to each other; however, the DNA sequences of these two stx(2d) operons were distinct. The STEC strains carrying these operons were isolated from retail ground beef. Surveillance for STEC strains expressing activatable Stx2d Shiga toxin among clinical cases may indicate the significance of this toxin subtype to human health.

Amino Acid Sequence↗