Strain typing and antimicrobial susceptibility of methicillin-resistant coagulase-positive staphylococcal species in dogs and people associated with dogs in Thailand.

AIMS: This study was to investigate and to characterize methicillin-resistant coagulase-positive staphylococci (MRCoPS) harboring in dogs and people associated with dogs in Thailand. METHODS AND RESULTS: Staphylococci were collected from 100 dogs, 100 dog owners, 200 small animal veterinarians and 100 people without pet association. Species of MRCoPS were identified phenotypically and genotypically. Molecular characteristics were determined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and SCCmec typing, and antimicrobial susceptibility was assayed by broth microdilution and by microarray analysis for resistance genes. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), methicillin-resistant Staphylococcus schleiferi subsp. coagulans (MRSSc) and methicillin-resistant Staphylococcus aureus (MRSA) were isolated from dogs (45, 17 and 1%, respectively), veterinarians (8, 2 and 1·5%, respectively) and dog owners (3, 2 and 0%, respectively). Seventeen sequence types (STs) were identified among 83 MRSP isolates which specifically carried SCCmec V, II-III, ΨSCCmec57395 and three uncharacterized SCCmec types. MRSP ST 45, 68 and novel STs including 169, 178, 181 and 183 were shared among canine and human isolates. Most of MRSA ST398 and MRSSc carried SCCmec type V. The MRCoPS commonly displayed multiple resistances to tested antimicrobials and carried various resistance genes. CONCLUSION: Variety of MRCoPS, especially new MRSP clones, distributed in dogs and people in Thailand. SIGNIFICANCE AND IMPACT OF THE STUDY: The existence of MRCoPS circulating between dogs and humans in Thailand provides indirect evidence of interspecies transmission and represents a potential public health hazard.

MRSA carriage in a tertiary governmental hospital in Thailand: emphasis on prevalence and molecular epidemiology.

We investigated prevalence and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) in a case-control study performed in a 900-bed tertiary governmental healthcare facility in Bangkok, Thailand. Multivariate unconditional logistic regression was used to identify risk profiles for MRSA carriage. Phage typing, pulsed-field gel electrophoresis (PFGE), polymorphisms of the coa and spa genes, hypervariable region (HVR) of SCCmec, multi-locus sequence typing (MLST), and identification of ST30/ST8 mosaic chromosome by heteroduplex-polymerase chain reaction (heteroduplex-PCR) were used to demonstrate a clonal relationship. Fifty-seven of 619 in-patients (9.2%) were positive for MRSA. Risk factors were being male, long admission, low modified McCabe score, history of MRSA infection, and use of broad spectrum cephalosporin. Molecular typing results indicated close relatedness among MRSA isolates. Successful epidemic subtypes were recovered from many different wards. However, all subtypes with different multi-locus sequence types were single locus variants (SLVs) of ST239. Heteroduplex-PCR gave two positive bands from ST8/ST30 mosaic chromosomal structures in all SLVs indicating all isolates were of the ST239 origin. The burden of MRSA nosocomial infections is high in the governmental tertiary hospital. The sole ST239 and its SLVs identified in this hospital is striking and calls for better policy for infection control and prevention.

Rifampin resistance in carbapenem-resistant Acinetobacter baumannii in Siriraj Hospital, Thailand.

There is a growing evidence on emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) in Thailand and recent treatment guidelines recommend a combination therapy using carbapenem and/or polymyxin with rifampin. Rifampin would be added in a combination therapy. The susceptibility of this pathogen to rifampin is not known, so we studied the rifampin susceptibility and possible mechanisms of resistance used by CRAB. The disk diffusion test was performed on 111 clinical isolates using 5 microg rifampin disk following CLSI guidelines. The inhibition zone was interpreted based upon the recommendation for Staphylococcus aureus (inhibition zone < 20 mm = resistant). Polymerase chain reaction (PCR) using the primers specific for arr-2 encoding rifampin ADP-ribosyltransferase was performed in all isolates. The rpoB DNA sequences from two isolates, with or without arr-2, were compared. All isolates under study were rifampin resistant. Inhibition zone was < 14 mm for all isolates. The arr-2 was positive for 35 isolates (31.5%) and these isolates correlated with high level of resistance (inhibition zone < 10mm). The DNA sequences of rpoB genes in arr-2 negative isolate showed mutations L904S, P906R, K909N and M1262K that might have roles in rifampin resistance. Mutations of rpoB genes in some isolates and possession of arr-2 in class 1 integron element were mechanisms for rifampin resistance and these resistant determinants can disseminate through both vertical and horizontal gene transfer. Under this circumstance, it is not recommended to use rifampin in the treatment of carbapenem-resistant A. baumannii in Thailand.

Integron-mediated rifampin resistance in Pseudomonas aeruginosa.

A new rifampin resistance gene, arr-2, has been found in Pseudomonas aeruginosa. The ARR-2 protein shows 54% amino acid identity to the rifampin ADP-ribosylating transferase encoded by the arr gene from Mycobacterium smegmatis. This arr-2 gene is located on a gene cassette within a class I integron.

Molecular epidemiology of the integron-located VEB-1 extended-spectrum beta-lactamase in nosocomial enterobacterial isolates in Bangkok, Thailand.

Over a 21/2-month period in 1999, 37 ceftazidime-resistant nonrepetitive enterobacterial isolates were collected from 37 patients in a Bangkok hospital, Thailand. Eighty-one percent of these strains expressed a clavulanic acid-inhibited extended-cephalosporin resistance profile. An identical extended-spectrum beta-lactamase (ESBL), VEB-1, was found in 16 unrelated enterobacterial isolates (Escherichia coli, n = 10; Enterobacter cloacae, n = 2; Enterobacter sakazakii, n = 1; and Klebsiella pneumoniae, n = 3) and in two clonally related E. cloacae isolates. The bla(VEB-1) gene was located on mostly self-conjugative plasmids (ca. 24 to 200 kb) that conferred additional non-beta-lactam antibiotic resistance patterns. Additionally, the bla(VEB-1) gene cassette was part of class 1 integrons varying in size and structure. The bla(VEB-1)-containing integrons were mostly associated with bla(OXA-10)-like and arr-2-like gene cassettes, the latter conferring resistance to rifampin. These data indicated the spread of bla(VEB-1) in Bangkok due to frequent transfer of different plasmids and class 1 integrons and rarely to clonally related strains. Plasmid- and integron-mediated resistance to rifampin was also found in enterobacterial isolates.