The Prevalence and the Resistance Profile of Methicillin-Resistant Staphylococcus aureus Colonized in the Nostrils of Cancer Patients in Namazi Teaching Hospital, Shiraz, Iran, 2011-12

Abstract

Background: Methicillin-resistant (MRSA) Staphylococcus aureus (S. aureus) are responsible for a vast number of nosocomial infections especially in immunocompromised subjects such as cancer patients. The presence of comorbidities including malignancies has been associated, with S. aureus bacteremia mortality. Thus, the detection of MRSA in this patients and the antibiotic susceptibility pattern of the isolates eases the selection of first-line medications and the prevention from further complications in cancer patients. The aim of this study was to determine the prevalence of MRSA infection and antibiotic susceptibility patterns of the isolates in pre and post-chemotherapy course in cancer patients.

Materials and Methods: From May 2011 to July 2012, 200 nostril samples of cancerous patients were obtained and cultured on blood agar plates. After isolation and confirmation of S. aureus, antibiotic resistance pattern of the isolates was determined pre-chemotherapy and after the chemotherapy against vancomycin, tigecycline, linezolid, chloramphenicol, and oxacillin using disk diffusion test following CLSI guidelines. Chi-square test was used for data analysis.

Results: Among a total number of 200 various cancer patients (64.5% females), 42 (21%) cases were positive for S. aureus and 7 (3.5 %) were MRSA carriers. Mean ages of MSSA and MRSA infected patients were 50.97±15.94 and 53.57±18.28 years old, respectively. In vitro susceptibility pattern of the MRSA and MSSA isolates to the 4 tested agents did not differed significantly after the chemotherapy in contrast with pre-chemotherapy state.

Conclusions: This study showed that chemotherapy does not change the susceptibility pattern of MRSA species to antibiotics of choice in cancer patients. However, the importance of controlling methicillin resistant staphylococcal infections in critical cases, specifically cancer cases, necessitates the early detection, further investigations on more effective medications.