Frequency of isolation and drug susceptibility of bacterial strains isolated from child oncohematological patients 2011-2014: A single center study.

BACKGROUND: Infections in pediatric patients with oncohematological diseases pose a huge therapeutic and diagnostic problem.

OBJECTIVES: The aim of the study was to investigate the etiology of bacteremia and the antibiotic susceptibility of pathogenic and colonizing bacterial strains in pediatric oncohematological patients.

MATERIAL AND METHODS: In the period 2011-2014, 17,209 positive test results, including 1,129 positive blood cultures, were subjected to a detailed analysis. The assessment of drug susceptibility was conducted in accordance with the CLSI (American), EUCAST (European), and KORLD (Polish) recommendations.

RESULTS: A high percentage (86-91%) of negative blood culture results was demonstrated. A predominance of Gram-positive bacteria was seen in all years (60-70%) in contrast to Gram-negative strains (30-40%). Coagulase-negative staphylococci (CNS) were the strains most frequently isolated from blood (41-47%) among all bacterial strains. Susceptibility to linezolid and vancomycin was 96-100%, and to teicoplanin 82-96%. Methicyllin-resistant coagulase-negative Staphylococcus (MRCNS) were isolated in 77-86%. All Staphylococcus aureus (S. aureus) strains were susceptible to glycopeptides and linezolid, while Enterococcus spp. was susceptible to linezolid. Apart from the year 2014, no methicillin-resistant S. aureus (MRSA) were isolated. Enterobacteriaceae (EN) were the most susceptible to imipenem and meropenem (91-100%) as well as to amikacin (77-93%). From 2013 to 2014, non-fermentative rods (NF) isolated from blood were less susceptible to imipenem and meropenem (71% and 67-71%, respectively) than to other antibiotics. It has been shown that strains isolated from blood have a statistically significantly different susceptibility to antibiotics (CNS and EN are less and NF is more susceptible) than those existing as colonizing flora.

CONCLUSIONS: Our results show that choosing appropriate antibiotics for treating infection in children with oncohematological diseases based on antibiograms for colonizing flora may be difficult because they may not take into account the more resistant strains. According to the antibiotic susceptibility of the strains isolated from blood in our center, the most viable active empirical and carbapenem-saving therapy could be conducted with piperacillin/tazobactam or cefepime.