Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of healthcare-associated infections and significant contributor to healthcare cost. Community-associated-MRSA (CA-MRSA) strains have now invaded healthcare settings. A convenience sample of 97 clinical MRSA isolates was obtained from seven hospitals during a one-week period in 2010. We employed a framework integrating Staphylococcus protein A typing and full-genome next-generation sequencing. Single nucleotide polymorphisms were analyzed using phylodynamics. Twenty-six t002, 48 t008, and 23 other strains were identified. Phylodynamic analysis of 30 t008 strains showed ongoing exponential growth of the effective population size the basic reproductive number (R0) ranging from 1.24 to 1.34. No evidence of hospital clusters was identified. The lack of phylogeographic clustering suggests that community introduction is a major contributor to emergence of CA-MRSA strains within hospitals. Phylodynamic analysis provides a powerful framework to investigate MRSA transmission between the community and hospitals, an understanding of which is essential for control.

Staphylococcus aureus is one of the main causes of foodborne diseases and a leading cause of nosocomial infections worldwide. Eleven (11) isolates from milk; 34 from meat and 23 of clinical source were subjected to phenotypic and biochemical characterizations for confirmation and further analysis for the presence of virulent genes, clonal relatedness and cytotoxicity profile. All isolates were positive for catalase production; 3, 11, and 7 isolates from milk, meat and clinical sources were coagulase positive. Polymerase chain reaction technique was used for the detection of 16S rRNA, clumping factor (cflA) and methicillin resistance (mecA) virulent genes. All isolates were positive for 16S rRNA; 100 and 45% of clinical; 73 and 64% of milk and none of the meat isolates were positive for cflA and mecA genes, respectively. Eight SmaI-based pulse-field gel electrophoresis (PFGE) clusters were identified at 80% similarity. Cytotoxic potential of the strains showed that 27.8, 24.1 and 22.2% of the strains tested had high, medium and low lactate dehydrogenase (LDH) release, respectively. These findings clearly demonstrate the presence of S. aureus in food and also in clinical infections, thus it should be a public health concern because even when virulent genes were not amplified in some strains, there may still be cytotoxicity effects.