The effect of age on the bacteria isolated and the antibiotic-sensitivity pattern in infections among cancer patients

Abstract

Background: Patients with cancer are predisposed to infections. Antimicrobial patterns and antibiotic sensitivity change with increasing age, making choice of empirical therapy more complicated.

Materials and methods: This single-center study aims to try and assess the influence of age on microbiology and antibiotic sensitivity of organisms causing infection in patients with malignant disease.

Results: The five most common bacterial pathogens isolated were Pseudomonas sp (245, 26.2%) > Enterocococcus sp (109, 11.66%) > Staphylococcus aureus (107, 11.44%) > Escherichia coli (106, 11.34%) > Klebsiella sp (99, 10.59%). There was no significant change in the distribution of Gram-positive and Gram-negative bacteria with age. However, there was an increase in the occurrence of the Enterobacteriacea group and a decrease in infections caused by nonlactose fermenters with increasing age. The ESBL production increased from 10.52% (12-19 years) to 24.88% (> 50 years) as did oxacillin resistance (from 14.3% to 28.1%) among S. aureus isolates. The activity of most antimicrobial agents decreased with increasing age. The decreasing trend of activity was statistically significant for meropenam (73.3-41.2%) against Pseudomonas sp. and for the activity of the aminoglycosides for Acinetobacter sp (61.1-17.4% for amikacin).

Conclusions: This suggests that empirical antibiotic therapy needs to be changed on the basis of the age of the patient. It also appears that combination therapy is essential for the empirical treatment of infections in elderly patients with cancer.