Infections in patients with solid tumors: analysis of microbiology laboratory records

Introduction: Patients with solid tumors (ST) are at increased risk for infections because of their malignancy and the anticancer therapy. Limited data are available for patients with non-hematologic malignancies.

Purpose: The types of infections, the most common causative agents and their antibiotic susceptibility were retrospectively studied in our oncology care center, housing a 40-bed adult oncology unit and an outpatient care center.

Material and methods: Microbiology sample records of all patients cared for in the Department of Oncology at Szent László Hospital from April 2003 to September 2004 were retrospectively analysed and compared with the clinical data. The most common underlying malignancies were gastrointestinal tract tumors. Microbiology cultures were obtained in cases of suspected bacterial infections. The most frequent examinations were blood cultures and urinalysis. Bloodstream infections (BSI) were categorised as monomicrobial or polymicrobial, community or hospitally acquired, or healthcare associated.

Results: During the 18-month study period, 25 episodes of BSIs were identified among 22 patients with ST. The source of BSI was not identified in 8 episodes (32%), among the remaining entry for the BSI, the urine tract was the most frequent, followed by colon tumor abscess. The total number of isolated BSI pathogens was 31. Of these, 61% were Gram-negative, 39% Gram-positive bacteria. Among the 31 isolated pathogens, Escherichia coli was the most common (48,5%), followed by Streptococcus alpha-hemolytic, Enterococcus spp., Streptococcus bovis, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter baumanni, Acinetobacter spp. and Staphylococcus coagulase-negative. Escherichia coli (44,1%) was the predominant bacterium in the diagnosed 59 urine tract infections (UTI) as well.

Conclusion: Most information on infections in patients with STs has been derived from the infectious complications of patients with hematologic malignancies and bone-marrow transplant recipients. More studies should be made on the characteristics of infections in ST patients.