THE IMPORTANCE OF IN-VITRO SUSCEPTIBILITY TESTING IN THE MANAGEMENT OF COMPROMISED HOSTS

Bacterial infection may be a life-threatening complication in the immu nocompromised host, especially in the face of profound and persistent granulocytopenia induced by cytotoxicity. Under these circumstances, a ntibiotic therapy is started on an empirical basis; however, knowledge of the antibiotic susceptibilities of the offending pathogen may repr esent a useful guide for therapy adjustments in individuals who do not respond satisfactorily to initial antibiotics. Careful antimicrobial susceptibility testing may also represent the first step of epidemiolo gy investigation of nosocomial outbreaks; moreover, knowledge of antib iotic susceptibility patterns of the prevalent pathogens in certain in stitutions mag. help clinicians to formulate empiric antimicrobial tre atments for febrile granulocytopenic patients. Careful quantitative st udies involving determination of the minimal inhibitory concentrations may help to evidence early, potentially clinically significant decrea ses in susceptibility to first choice antibiotics for important nosoco mial pathogens. Relationships between appropriate or inappropriate tre atment, based on in-vitro susceptibility testing results, and clinical outcome may help to define the clinical significance of some emerging bacterial pathogens in immunocompromised patients.