Molecular typing of clinical, colonizing, and environmental isolates of Staphylococcus aureus and comparison with World isolates

Staphylococcus aureus ( S.aureus ) is a facultative anaerobe that colonizes humans' nasal cavity, skin, and other mucosal surfaces. The bacterium can cause local and systemic infections, including skin and soft tissue infections, bacteremia, endocarditis, and osteomyelitis. It is associated with hospital-acquired infections, and the emergence of Methicillin-resistant S.aureus (MRSA), a difficult-to-treat pathogen, is of concern in hospitals. This is a retrospective analytical study. A hundred S. aureus isolates from various sources stored in our repository were used in the study. These isolates were obtained from clinical samples, surveillance samples from healthcare workers and patients and hospital environmental samples. Fragments of seven housekeeping genes were amplified as given in the PUBMLST site. (https://pubmlst.org/organisms/ staphylococcus aureus). The amplified fragments were sequenced. STs were determined by comparing the known alleles in the database. New Sequence types were assigned to novel STs. We analyzed all the isolates in the database according to the country, isolate types, etc. A total of 100 isolates of S. aureus from clinical, surveillance and hospital environmental samples, present in the repository, were included. MLST was performed for 55 isolates. Sequence types encountered were ST22, ST5, ST364, ST1910, ST5939, ST5529, ST7442, ST672, and ST9162. The rest were new types. Most of our isolates belonged to CC5. These were compared with those of the Indian and World isolates in the PUBMLST site. Sequence types help to understand their evolution. Efficient infection control and surveillance strategies will help control the transmission of MRSA in the hospital.