Comparative analysis of multidrug-resistant, non-multidrug-resistant, and archaic methicillin-resistant Staphylococcus aureus isolates from Central Sydney, Australia.

In this study, the phenotypic and genotypic characteristics of 50 methicillin-resistant Staphylococcus aureus (MRSA) isolates (43 contemporary and 7 archaic strains from the mid-1960s) from four Sydney hospitals in the central Sydney area were compared. Phenotypic analysis based on antibiotic profiles and phage typing patterns categorized the MRSA isolates into three major groups: multidrug resistant (mMRSA), non-multidrug resistant (nmMRSA), and archaic. The nmMRSA isolates could be further subdivided into nmMRSA group 1, which was phage typeable and similar to the archaic group; nmMRSA group 2, which was non-phage typeable and only resistant to ciprofloxacin; and nmMRSA group 3, which was also nontypeable and generally resistant to other antibiotics.

Genetic analysis of Pseudomonas aeruginosa isolates from the sputa of Australian adult cystic fibrosis patients.

Genetic investigations were carried out with 50 phenotypically selected strains of Pseudomonas aeruginosa from 18 patients attending an Australian cystic fibrosis (CF) center. The isolates were analyzed by restriction fragment length polymorphism (RFLP) analysis by pulsed-field gel electrophoresis (PFGE). Phylogenetic analysis of the macrorestriction patterns showed rates of genetic similarity ranging from 76 to 100%; 24 (48%) of the strains from 11 patients had greater than 90% similarity.

Detection and expression of methicillin/oxacillin resistance in multidrug-resistant and non-multidrug-resistant Staphylococcus aureus in Central Sydney, Australia.

Ninety clinical Staphylococcus aureus isolates from separate patients were examined phenotypically and genotypically for susceptibility to methicillin/oxacillin. Thirty were methicillin/oxacillin susceptible and 60 were methicillin and oxacillin resistant (MRSA). The 60 MRSA isolates examined were subdivided into two groups according to their antibiotic profiles and comprised 30 non-multidrug-resistant (NMDR) isolates, resistant to less than two non-beta-lactam antibiotics, and 30 multidrug-resistant (MDR) isolates, resistant to three or more non-beta-lactam antibiotics.