Streptococcus pneumoniae and Haemophilus influenzae nasopharyngeal molecular detection in children with acute respiratory tract infection in SANADOR Hospital, Romania.

Introduction. Streptococcus pneumoniae and Haemophilus influenzae are both commensals of the human nasopharynx with a high capacity to cause upper and lower respiratory tract infections.Aim. Molecular testing of nasopharyngeal samples from children at the primary care paediatric department presenting with acute respiratory tract infections (ARTIs).Methodology. From June 2016 to May 2017, 156 nasopharyngeal swabs from children diagnosed with ARTIs who had been admitted to or followed up as outpatients at the Department of Paediatrics, SANADOR Hospital (Bucharest, Romania) were tested for the presence of S. pneumoniae, H. influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, Bordetella pertussis and Bordetella parapertussis DNA.Results. S. pneumoniae had the highest detection rate (53.8 %, n=84/156), followed by H. influenzae (41 %, n=64/156) and S. pneumoniae/H. influenzae co-detection (26.2 %, n=41/156).Conclusion. A definitive laboratory diagnosis of these micro-organisms can be made for invasive disease, but there are difficulties in establishing the aetiology for mucosal infection. Molecular detection tests could complement culture-based tests by strengthening their surveillance.

Methodology optimization and diversification for the investigation of virulence potential in Haemophilus influenzae clinical strains.

Ten Haemophilus influenzae strains were isolated from patients aged between 1.6 - 24 years, with various diagnoses (acute meningitis, acute upper respiratory infection, otitis media and acute sinusitis). Identification was based on phenotypic and molecular characteristics; antibiotic susceptibility testing was performed by diffusion method according to CLSI standards 2011 for seven antibiotics. The results of molecular testing showed that all the studied strains produced an amplicon of 1000 bp with ompP2 primers indicating that all strains were H. influenzae. For six strains, the PCR amplicon obtained with bexA specific primers, proving that the strains were capsulated. The results of phenotypic testing showed that four strains were ampicillin nonsusceptible and (beta-lactamase-positive. The virulence potential of H. influenzae clinical strains was investigated by phenotypic methods, including the assessment of the soluble virulence factors on specific media containing the biochemical substratum for the investigated enzymatic factor, as well as the adherence and invasion capacity to HeLa cells monolayer using Cravioto modified method. The studied strains exhibited mainly a diffuse adherence pattern and different adherence indexes. Interestingly, two strains isolated from the same pacient (blood and CSF) showed a different degree of invasiveness, the strain isolated from blood being 20 times more invasive than the one isolated from CSF.

Influence of orthodontic treatment on oral streptococci.

UNLABELLED: Objective of this study is to evaluate the changes of the oral microbial flora, concentrating on the oral streptococci, after the first 3 and 6 months of orthodontic treatment. MATERIALS AND METHODS: 40 patients, aged 7-17, that presented for orthodontic treatment between April and September 2010 in the Department of Orthodontics and Dento-Facial Orthopedics of "Carol Davila" University of Medicine and Pharmacy, Bucharest have been selected. According to the protocol, coronary and subgingival plaque was collected from the dental surface before starting any orthodontic treatment (T0), 3 months after wearing orthodontic appliances (T1) and 6 months after wearing orthodontic appliances (T2). The samples were studied in Cantacuzino National Institute of Research-Development for Microbiology and Immunology [isolation on Columbia agar with 5% sheep blood, identification on morphotinctorial, growth and biochemical characteristics using API 20 STREP (BioMerieux)]. Bacterial concentration (colony-forming units/sample = CFU/sample) for the aerobic and anaerobic flora was calculated by the serial dilution method of counting bacteria. RESULTS: 106 strains of oral streptococci were isolated from dental plaque, belonging to 6 species (Streptococcus mitis, Streptococcus oralis, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis and Streptococcus acidominimus), 37 strains of oral streptococci in patients from group I (T0), 40 strains from group II (T1) and 29 strains of oral streptococci from group III (T2). After 3 months (T1) the aerobic bacteria percentage, detected at a concentration between 10(5) and 10(6), increased from 30 to 38.2%. The percentage of patients with a bacterial concentration higher than 10(6) CFU/sample increased from 5% to 8.8%. The samples colected at T2 (patients examined after 6 months of orthodonic treatment) presented a lower bacterial concentration, as compared to group II (T1). The most common isolated species of streptococci were S. salivarius, S. oralis and S. mutans (37.5%, 22.5% and 10%), whose frequency increased after 3 months of treatment to 41.14%, 32.3% and respectively 14.4%, returning after 6 months of treatment at values similar to those recorded before beginning the orthodontic treatment. CONCLUSIONS: Presence of orthodontic appliances may produce a transitory increase of bacterial concentration (CFU/sample) and isolation rate of oral streptococci, returning to the level prior to the application of these devices after a time interval of several months.