PURPOSE: Risk factors for hospital-acquired pneumonia (HAP) include an ICU stay. The ARM Program, an ongoing project of the University of Florida, has collected antibiogram/sensitivity report data from 364 US institutions. These data comprise a national aggregate database containing 29.5 million drug/isolate comparisons. This study examined ICU isolate antimicrobial susceptibility rates of P aeruginosa and S aureus, two of the most common causes of HAP.
METHODS:P aeruginosa and S aureus ICU isolate/drug comparisons for 1997-2005 were reviewed for antibiotics used to treat HAP: carbapenems (imipenem), aminoglycosides (amikacin, gentamicin, tobramycin), fluoroquinolones (ciprofloxacin, levofloxacin), cephalosporins (ceftazidime, cefepime), extended-spectrum penicillin antibiotics (piperacillin), or the combination of piperacillin and tazobactam (a beta-lactamase inhibitor). Data were available for Northeast, Southeast, and Southwest, summed for a national total.
RESULTS: For P aeruginosa (n=17,883), national susceptibility to imipenem was 78.2% (range, 58.1% in Southwest to 85.7% in Southeast); to amikacin, 89.5% (87.7% in Southeast to 92.9% in Southwest); gentamicin, 72.7% (53.8% in Southwest to 76% in Southeast); tobramycin, 86.1% (71% in Southeast to 88.2% in Northeast); ciprofloxacin, 67.2% (66.5% in Northeast to 67.6% in Southeast); levofloxacin, 56.9% (46% in Southwest to 60.9% in Northeast); ceftazidime, 78.7% (56.9% in Southwest to 81.9% in Northeast); cefepime, 71.2% (57.9% in Southwest to 76.7% in Northeast); piperacillin, 81.6% (62% in Southwest to 84.6% in Southeast); and piperacillin/tazobactam, 86.3% (80.8% in Southwest to 85.9% in Northeast. For S aureus (n=8128), national susceptibility rates ranged from 98% for amikacin and 96.2% to gentamicin to 37.5% for levofloxacin; these rates were 52.4% for imipenem and 53.6% for ciprofloxacin.
CONCLUSION:P aeruginosa ICU isolates are most resistant to fluoroquinolones and most susceptible to amikacin, piperacillin/tazobactam, and tobramycin. S aureus ICU isolates are most resistant to levofloxacin and most susceptible to amikacin and gentamicin.
CLINICAL IMPLICATIONS: Optimal therapy for HAP should include assessment of risk factors, including local antimicrobial resistance patterns. These data suggest HAP should not be treated with fluoroquinolones if P aeruginosa or S aureus are suspected of being the infectious organisms.
DISCLOSURE: John Gums, Grant monies (from industry related sources) AstraZeneca, Roche Pharmaceuticals.