Microbial spectrum and antibiotic susceptibility profile of gram-positive aerobic bacteria isolated from cancer patients.

PURPOSE

Cancer patients are particularly susceptible to nosocomial infections because of their compromised immune system, and because of the nature of treatment practices they experience. Recently, a shift of the microbial spectrum of cancer patients from gram-negative to gram-positive has been demonstrated. This study analyzed the distribution and the antimicrobial resistance of gram-positive bacteria isolated from cancer patients in Egypt.

PATIENTS AND METHODS

We examined the microbial spectrum of gram-positive bacteria in patients with hematologic malignancies and solid tumors. In addition, we also studied the antimicrobial resistance of pathogens accounting for the majority of gram-positive infections in these cancer patients.

RESULTS

Most of gram-positive isolates from urinary tract (100%), respiratory tract (89.7%), and bloodstream infections (BSIs; 65.5%) were obtained from leukemic patients. All gram-positive isolates from skin infections were isolated from solid-tumor patients. In both leukemic and solid-tumor patients, gram-positive bacteria causing nosocomial BSI were mainly Coagulase-negative staphylococcus (CNS) and S. aureus, whereas gram-positive bacteria causing nosocomial RTI were mainly alpha-hemolytic streptococci and CNS. Gram-positive bacteria were not isolated from GI tract infections. S. aureus, CNS, and alpha-hemolytic streptococci demonstrated methicillin resistance (81.5%, 92.3%, and 90% resistance, respectively). S. aureus and CNS were susceptible to linezolid (15.4% and 0% resistance, respectively), and vancomycin (15.5% and 11% resistance, respectively).

CONCLUSION

This is the first study to report the emergence of vancomycin- and linezolid-resistant S. aureus in Egypt. Newer generation quinolones (moxifloxacin and gatifloxacin) were more active than older quinolones (ciprofloxacin and ofloxacin) against S. aureus and CNS, suggesting the use of newer generation quinolones in the prophylaxis of cancer patients.