Evolution of a 72-Kilobase Cointegrant, Conjugative Multiresistance Plasmid in Community-Associated Methicillin-Resistant Staphylococcus aureus Isolates from the Early 1990s.

Horizontal transfer of plasmids encoding antimicrobial resistance and virulence determinants has been instrumental in Staphylococcus aureus evolution, including the emergence of community-associated methicillin-resistant S. aureus (CA-MRSA). In the early 1990s, the first CA-MRSA strain isolated in Western Australia (WA), WA-5, encoded cadmium, tetracycline, and penicillin resistance genes on plasmid pWBG753 (∼30 kb). WA-5 and pWBG753 appeared only briefly in WA; however, fusidic acid resistance plasmids related to pWBG753 were also present in the first European CA-MRSA isolates at the time. Here, we characterize a 72-kb conjugative plasmid, pWBG731, present in multiresistant WA-5-like clones from the same period. pWBG731 was a cointegrant formed from pWBG753 and a pWBG749 family conjugative plasmid. pWBG731 carried mupirocin, trimethoprim, cadmium, and penicillin resistance genes. The stepwise evolution of pWBG731 likely occurred through the combined actions of IS257, IS257-dependent miniature inverted-repeat transposable elements (MITEs), and the BinL resolution system of the ß-lactamase transposon Tn552 An evolutionarily intermediate ∼42-kb nonconjugative plasmid, pWBG715, possessed the same resistance genes as pWBG731 but retained an integrated copy of the small tetracycline resistance plasmid pT181. IS257 likely facilitated the replacement of pT181 with conjugation genes on pWBG731, thus enabling autonomous transfer. Like conjugative plasmid pWBG749, pWBG731 also mobilized nonconjugative plasmids carrying oriT mimics. It seems likely that pWBG731 represents the product of multiple recombination events between the WA-5 pWBG753 plasmid and other mobile genetic elements present in indigenous community-associated methicillin-sensitive S. aureus (CA-MSSA) isolates. The molecular evolution of pWBG731 saliently illustrates how diverse mobile genetic elements can together facilitate rapid accrual and horizontal dissemination of multiresistance in S. aureus CA-MRSA.

Complete Genome Sequence of a Staphylococcus aureus Sequence Type 612 Isolate from an Australian Horse.

Staphylococcus aureus is a serious pathogen of humans and animals. Multilocus sequence type 612 is dominant and highly virulent in South African hospitals but relatively uncommon elsewhere. We present the complete genome sequence of methicillin-resistant Staphylococcus aureus strain SVH7513, isolated from a horse at a veterinary clinic in New South Wales, Australia.

Oral health status and access to dental care for ohio head start children.

PURPOSE: The purpose of this survey were to assess the dental caries prevalence rate among children enrolled in Ohio's Head Start programs and assess factors relating to their dental care access. METHODS: Oral screenings were conducted on 2,555 children, ages 3 through 5 years, at 50 Ohio Head Start centers using probability-proportional-to-size sampling. In addition, parental responses to 6 access-oriented questions on the consent form were analyzed. RESULTS: Overall, 38% of 3- to 5-year-old Head Start children screened had experienced dental caries, and 28% had at least 1 untreated decayed tooth. Of the children with caries experience, 73% had decayed teeth, while the remaining 27% had restorations only. Among children, there were no statistically significant differences associated with race or payment method. With regard to dental care access, 11% of Head Start parents reported they could not get wanted dental care for their children during the previous 12 months, most often due to cost of care/lack of insurance. Nine percent of children had a toothache in the previous 6 months. Although 85% of Head Start children had visited a dentist in the previous 12 months, another 10% had never visited a dentist. CONCLUSIONS: The significant prevalence rate of dental caries among Ohio Head Start children is consistent with other states' reports. Although almost 9 of 10 children visited a dentist during the year, three fourths of children with dental caries did not have their care completed by the time they were screened during the second half of the school year. Oral health disparities according to race and payment source were not found among Ohio Head Start children.