Clinical Microbiology and Antimicrobial Chemotherapy. 2011; 13(3):231-240
To determine causative agents of hospitalacquired pneumonia (HAP), their incidence rates, and susceptibility to antimicrobial agents in patients with hematological malignancies in an intensive care unit (ICU).
Broncho-alveolar lavage (BAL) specimens obtained from oncohaematologic patients with pneumonia hospitalized to the ICU between December 2009 and December 2010 were retrospectively studied.
A total of 142 BAL specimens were obtained from 72 hospitalized patients aged of 19 to 86 years. A half of patients had agranulocytosis; 60% of patients were received MV for 1 to 93 days; the mean length of ICU stay was 15 days. BAL culture positivity increased with increasing length of ICU stay: ≤2 weeks vs. >2 weeks (42–54% vs. 76%). Isolation rates for A. baumannii were as follows: at the time of ICU admission – 15%, at the end of first week – 50%, >2 weeks – 61%. Susceptibility of A. baumannii isolated at the first week was as follows: carbapenems – 14%, amikacin – 33%, netilmicin – 25%. All A. baumannii isolates obtained after first week were resistant to carbapenems and aminoglycosides and remained susceptible to colistin and tigecycline only. The incidence rates of P. aeruginosa were increasing from 10% to 18%. All P. aeruginosa isolates were susceptible to colistin, 1⁄3 of the isolates were susceptible to carbapenems, and most isolates were non-susceptible to cephalosporins, aminoglycosides, and fluoroquinolones. Enterobacteriaceae were susceptible to carbapenems, amikacin, and colistin. Gram-positive pathogens were methicillin-resistant and susceptible to vancomycin and linezolid. A total of 13% of BAL cultures were positive for Pneumocystis carinii. Invasive pulmonary aspergillosis was diagnosed in 17 of 72 patients (23.6%). Asperigillus spp. was cultured in 8 patients only; the remaining cases were diagnosed by positive galactomannan test. Cytomegalovirus DNA was detected in BAL specimens using PCR in 26.1% of cases.
Multidrug resistant Gram-negative microorganisms, such as A. baumannii and P. aeruginosa, are predominant among causative agents of hospital-acquired pneumonia in patients with hematological malignancies hospitalized to ICU. Drugs of choice for empiric antimicrobial therapy may be combination of a carbapenem with colistin.