Common bacterial cultures from oral mucosa after hematopoietic stem cell transplantation: Dependence on the patient characteristics and therapeutic factors

Abstract

Normal aerobic and facultative anaerobic microbiota colonizing oral mucosa is usually identified at clinical laboratories. Its composition may be important index of immunocompromised conditions. These parameters are scarcely studied in patients undergoing hematopoietic stem cell transplantation (HSCT). The aim of this work was to evaluate incidence of common aerobic and facultative anaerobic microbiota cultured from oral samples taken before HSCT and, by clinical indications, within 4 months after the treatment. Patients and methods We evaluated results of bacterial cultures from oral smears taken in 202 patients with oncohematological and inborn diseases at the age ranging from 1 to 69 years subjected to allogeneic HSCT. The analysis was performed for 3 age groups: 1-5, 6-14, 15-21, and >22 years old. Results In total observation group of 630 oral samples, the bacterial cultures proved to be positive in 61.8% of specimens. The most common microorganisms were as follows: S.viridans 245/630 (38.9%); K.pneumoniae 42/630 (6.7%); S.epidermidis 120/630 (19.1%); Neisseria spp. 66/630 (10.5%); Corynebacterium spp. 78/630 (12.4%). The incidence of microbial detection was time dependent, with significant decrease in S.epidermidis, Corynebacterium spp. and Klebsiella spp. during 1st month posttransplant which could be explained by early effective antibacterial decontamination since the time of conditioning in early posttransplant period. We have shown that the frequency of positive tests for S.viridans and K.pneumoniae in these samples were different for distinct age groups, i.e., the positivity rates were significantly higher in youngest children (up to 5 years old) and in adult patients (>22 years old), as compared with elder children and adolesсents. Incidence of K.pneumoniae in oral samples was found to be sufficiently increased 2-3 months after HSCT, being associated with severe infectious complications, with broad antibiotic resistance in most culturable Klebsiella isolates from the patients. For clinical indications, teeth extraction was made in 10 cases during 1st month after HSCT, with Pseudomonas aeruginosa in 3 samples, S.viridans in 2 cases isolated from the local gum wounds. In conclusion, the immunotoxic effects of cytostatic therapy and microbiota analysis post-HSCT deserve further studies, including biodiversity analysis of oral microbiota by means of 16S rRNA gene sequencing. These results may represent a basis for rational antibacterial therapy in HSCT.