Non-typeable strains of Haemophilus influenzae - representative of normal microflora or of the pathogen?
Untypeable strains of Haemophilus influenzae (Haemophilus influenzae) colonize the lining of the upper respiratory tract, but can spread and cause infections such as conjunctivitis, otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease and, in some areas, pneumonia. The results of a 2-year epidemiological study carried out in Spain in 2004-2005. , has shown that the frequency of H. influenza transport in healthy children under 5 years old attending kindergartens, on average, is 42% and varies considerably according to establishments - from 12% to 83%. The vast majority (99%) of the isolates were atypical strains of hemophilic bacilli. By pulsed gel electrophoresis, 127 different H genotypes were identified. influenzae, with at least 2 different genotypes found in each DDU. In 140 children, the study was repeated the following year, and in 100% of the cases, different hemophiliac strains were isolated. The isolated isolates showed resistance to cotrimoxazole and ampicillin, however, the mechanisms of resistance to ampicillin differed at different times of the study: in 2004, changes in penicillin binding proteins (PSB ) were more common and in 2005, beta-lactamase production was observed. Thus, the results of this study demonstrate significant genetic variability and inconstancy in the non-typable strains of H. colonizing the nasopharynx influenzae in healthy children.
Over the past 20 years, a gradual but steady increase in the proportion of invasive infections caused by untypeable strains of H. has been observed in the influenza world, the most vulnerable being young children and the elderly . Patients with chronic diseases also have a high risk of developing an infection and its side effects. The introduction of vaccination against pneumococcal infections also leads to a change in the etiological structure of respiratory tract infections, with a decrease in the proportion of pneumococci and a relative increase in the role of hemophilic bacilli, in particular in acute otitis media. in children.
Beta-lactamase production is the main mechanism of resistance of hemophiliac bacilli strains, but strains of ampicillin-resistant beta-lactamazones H. have also spread to certain regions of the world. influenzae (BLNAR). Further distribution of these strains may require a review of existing recommendations for antibiotic therapy for upper and lower respiratory tract infections. In this regard, there is a need to develop active international cooperation and to use standard typing protocols and methods to carry out epidemiological surveillance of this clinically significant pathogen.