Phage sensitivity profiles of a nasopharyngeal opportunistic pathogen in Streptococcus pneumoniae carrier children with recurrent respiratory infections

Aim. To study the nature of microbiota and estimating the susceptibility to antibiotics and bacteriophages of conditionally pathogenic microflora of the nasopharynx in children-pneumococcal carriers with recurrent respiratory infections.

Methods. Researching microflora was conducted in 182 pneumococcal carriers receiving help in Kazan Scientific and Research Institute of Epidemiology and Microbiology. Microbial identification, testing of susceptibility to antibiotics and bacteriophages was carried out following the regulatory documentation. Bacterial isolates were confirmed by mass spectrometry. The phage titer was determined by the method of agar layers according to Grazia.

Results. Nasopharyngeal S. pneumoniae species was presented by Staphylococcus spp., Moraxella spp., Haemophilus spp., Corynebacterium spp., Klebsiella spp and Candida spp. The antimicrobial resistance profiles of Streptococcus pneumoniae: resistant to oxacillin was detected in 20.7% of strains, to erythromycin in 45.9%, to clindamycin in 20%, to trimethoprim-sulfamethoxazole in 18.4%. 19.6% of isolates were multidrug-resistant (MDR, resistant to 3 or more antimicrobial agents). Phage susceptibility test of S. pneumoniaе showed that 97.2% of isolates were resistant to streptococcal bacteriophage, 75% to pyobacteriophage. All antibiotic-resistant strains remained susceptible to Streptococcus phages. The phage titer of Klebsiella in agreement with Grazia method of Kl. pneumoniae ranged from 9×10–6 to 5×10–5 PFU/mL. The ranking results of activities of antistaphylococcal antibiotics (effectiveness descending): fusidic acid > mupirocin > chloramphenicol > cyprofloxacin erythromycin.

Conclusion. Nasopharyngeal microbiota of pneumococci carriers children is represented by a variable polymicrobial association; nasopharyngeal strains are effectively lysed by bacteriophages; mono- and polyvalent bacteriophages can be used as an alternative to antibacterial treatment in Streptococcus pneumoniae carriers children with recurrent respiratory infections.