Molecular characterization and antibiotic susceptibility of methicillin-resistant Staphylococcus aureus in immunocompromised cancer patients.

Objective: This study aims to analyze MRSA isolates from pediatric cancer patients, determine the prevalence of PVL genes and assess their clinical implications.

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) infections pose significant challenges in pediatric oncology settings. Understanding the prevalence, genotypic characteristics, and antibiotic resistance patterns of MRSA aids in improving patients' outcomes.

Methods: A total of 120 S. aureus isolates from patients receiving chemotherapy for treatment of malignant diseases and developing BSIs during febrile episodes were examined. Isolates were identified using Gram staining, biochemical tests, and VITEK 2-Compact 15. Antimicrobial susceptibility was tested using the Kirby-Bauer disk diffusion method. Molecular characterization included PCR assays for 16S rDNA, multiplex PCR for femA, mecA, and PVL genes, and SCC_mec type.

Results: Out of 120 isolates of Staphylococcus aureus, 97 (80%) isolate possessed mecA gene and were identified as MRSA, MRSA bacteremia harboring PVL gene was detected in cancer patients in Egypt at 26.8% of MRSA isolates. The study identified a higher fatality rate in patients aged 6-10 years (26.7%) compared to other age groups (p < 0.044). Deceased patients exhibited higher leukocyte counts and lower platelet counts. Solid tumor patients had significantly higher neutrophil and monocyte counts. Type II of SCC_mec correlated with survival and mortality, with the PVL gene being a significant factor. Type III showed a higher prevalence of femA and mecA among survivors, while Type IVb was associated with better outcomes. Antibiotic susceptibility revealed high resistance to cefoxitin, cefepime, and Tazocin, but better sensitivity to ciprofloxacin and gentamicin, particularly in Types IV and V.

Conclusion: The study highlights the age-related fatality differences and the impact of HCV infection on survival rates. Hematologic parameters and SCC_mec types play a crucial role in patient outcomes. The observed antibiotic resistance patterns necessitate the need for targeted therapies based on MRSA SCC_mec types.