Genetic determinants of Staphylococcus haemolyticus in commensal and clinical isolates / Farhan Haziq Azharollah

In this study, the genetic determinants in both commensal and clinical isolates of S. haemolyticus which includes Multi-Drug Resistance (MDR), Staphylococcal Cassette Chromosome mec (SCCmec) typing and biofilm formation were characterized. A total of 50 commensal and 98 clinical isolates of S. haemolyticus were successfully isolated and tested against eleven types of antibiotics. From these, 40.0% of the commensals were MDR strains while a higher percentage of 69.4% of the clinical isolates were also MDR strains. The antibiotic profile data indicates the natural resistance ability of S. haemolyticus against killing by antibiotics regardless whether they are from commensal or clinical isolates. It also shows that MDR strains are more prominent among the clinical strains than the commensals. In contrast, all the isolates regardless of commensals or clinical were susceptible against vancomycin suggesting that this antibiotic is suitable for treatment in S. haemolyticus infections. SCCmec Type II was found to be a dominant typing for both commensal and clinical isolates at 90.0% and 98.99% respectively followed by Type V, Type I, Type IV and Type III. Similar pattern of typing observed indicates the possibility that the clinical isolates of S. haemolyticus could probably originated from the commensals strains that had successfully enter the host and caused infections. Unlike S. epidermidis, the majority of S. haemolyticus did not form biofilm on micro-titre plate nor did they harbour the icaAD gene. This suggests that biofilm formation may not be a virulent factor for the pathogenicity of S. haemolyticus. Isolate E1, S90 and A114 were further subjected to de novo Next Generation Sequencing (NGS). The results revealed that these isolates harbour eleven antibiotics resistance genes, nine SCCmec sequences, sequences homologous to two phages and nine plasmids, and they also carry the IS1272 insertion sequences. Hence, it appears that these genetic determinants are widespread among the S. haemolyticus isolates and may serve as “vehicles” for the transmission of antibiotics resistance. However, there is not enough evidence to conclude if an isolate can progressively become resistance to more antibiotics by sequentially accumulating these genetic determinants tested