Fluoroquinolones, antimicrobial resistance and neutropenic cancer patients

PURPOSE OF REVIEW: Fluoroquinolone antibiotics are widely used in our communities and healthcare facilities. This review focuses upon the relationship between fluoroquinolone use and the rising prevalence in neutropenic cancer patients of multidrug resistant pathogens including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, Clostridium difficile, and aerobic Gram-negative bacilli. RECENT FINDINGS: Fluoroquinolones such as ciprofloxacin or levofloxacin are efficacious for the prevention and treatment of neutropenic fever syndromes, including infections due to aerobic Gram-negative bacilli. Recent clinical practice guidelines recommend their prophylactic use in acute leukaemia patients receiving intensive remission-induction, postremission consolidation, or salvage induction therapy, and haematopoietic stem cell transplant recipients during pre-engraftment when the duration of profound neutropenia (absolute neutrophil count <0.1 × 10(9)/l) is at least 7 days. These same agents combined with amoxicillin/clavulanate are recommended for oral outpatient empirical antibacterial treatment of febrile neutropenic patients at low risk for medical complications. Fluoroquinolone-resistant Enterobacteriaceae is linked to community fluoroquinolone consumption. Prophylaxis efficacy is reduced when the prevalence of fluoroquinolone Gram-negative bacillary resistance exceeds 20%. Widespread use encourages the transmissibility of multiclass antimicrobial resistance genes among Gram-negative bacilli. Fluoroquinolone-driven colonization with MRSA enhances the risk of subsequent infection, the use of vancomycin, and risk of colonization by vancomycin-resistant Enterococcus spp. The relative roles of widespread fluoroquinolone use and ineffective infection prevention and control practices in encouraging the spread of virulent C. difficile-associated diarrhoea in healthcare facilities remain controversial. SUMMARY: Widespread use of antibacterial agents of one class can encourage multiclass drug resistance, which reduces prophylaxis and treatment efficacy in neutropenic cancer patients.