The prevalence of genes encoding leukocidins in Staphylococcus aureus strains resistant and sensitive to methicillin isolated from burn patients in Taleghani hospital, Ahvaz, Iran

Abstract

BackgroundStaphylococcus aureus has been recognized as an important human pathogen and is the major cause of nosocomial infections. Various strains of S. aureus produce bicomponent toxins such as LukE/D, and PVL. The toxins subunits bind to leukocyte cell membrane inducing trans-membrane pore formation and subsequent cell lysis. PVL is an example of these toxins and causes leukocyte destruction and tissue necrosis. It seems that S. aureus strains comprising LukE/D and PVL genes are more important in the disease process and associated with severe skin diseases, fatal pneumonia and osteomyelitis with high morbidity and mortality. ObjectiveThe aim of this study was to determine the prevalence of genes encoding leukocidins in S. aureus strains resistant and sensitive to methicillin isolated from burn patients in Taleghani hospital, Ahvaz, Iran. MethodsIn an 11-month study, 203 staphylococci isolates were collected from burn patients. The isolates were examined by traditional culture method for detecting S. aureus strains and further confirmation with standard biochemical tests including catalase, coagulase and DNase. DNA was extracted from bacterial colony by simple boiling method. Using template DNA, the polymerase chain reaction technique (PCR) was used to detect mecA gene for detecting methicillin resistant S. aureus strains (MRSA), PVL and Luk-E/D genes. ResultsNinety-five (46.8%) out of total tested isolates were identified as S. aureus. Based on the results from PCR, 83 strains (87.36%), were mecA positive, so they were resistant to methicillin and the rest were sensitive to methicillin (MSSA). The prevalence of PVL and LukE/D genes in MRSA strains were (7.23%) and (66.26%) respectively. While this prevalence were (33.3%) for both genes in MSSA strains. ConclusionThere were PVL and LukE/D positive MRSA isolates with high prevalence in evaluated hospital. Since resulting diseases from these bacteria are severe and may even lead to death, the prevention of disease progress is desired by early diagnosis and proper treatment.