Clinical Microbiology and Antimicrobial Chemotherapy. 2019; 21(3):207-211
To evaluate Staphylococcus species diversity and methicillin resistance in nosocomial infections.
Staphylococci isolated from blood, bronchoalveolar lavage fluid, cerebrospinal fluid, post-operative wound exudates, urine and other samples were identified to species level with MALDITOF mass-spectrometry. Methicillin resistance was evaluated according to EUCAST guidelines.
A total of 3239 consecutive Staphylococcus strains isolated in a tertiary-care medical centre, accumulating patients from all Russian regions were identified in 2016–2017 as 1460 (45.1%) of S. aureus strains and 1779 (54.9%) of coagulase-negative staphylococci, presenting 12 species (S. epidermidis, S. haemolyticus, S. hominis, S capitis, S. warneri, S. lugdunensis, S. simulans, S. caprae, S. saprophyticus, S. cohnii, S. sciuri, S. auricularis). S. epidermidis was isolated in 1164 (35.9%) samples, S. haemolyticus – in 305 (9.4%), S. hominis in 215 (6.6%), S. capitis in 46 (1.4%) cases. Other Staphylococcus spp. were isolated from less than 1% of samples. Methicillin-resistant were 1628 (50.3%) Staphylococcus strains, including 202 (13.8%) S. aureus isolates, 933 (80.2%) – S. epidermidis, 283 (92.5%) – S. haemolyticus, 182 (84.7%) – S. hominis, 8 (17.4%) – S. capitis.
Significant species diversity in staphylococci, isolated from patients samples in a multidisciplinary medical center in Saint-Petersburg in 2016–2017, was revealed. S. aureus prevailed in nosocomial infections of different localizations, accounting for more than a half of isolated Staphylococcus spp. Among coagulase-negative staphylococci 1⁄3 of isolated strains were S. epidermidis (the most common species in this group). Methicillin resistance was found in a half of Staphylococcus spp. strains. The level of methicillin-resistance in S. aureus was 13.8%, with decrease from 15.6% in 2016 to 12.3% in 2017. S. haemolyticus, S. hominis and S. epidermidis showed the highest level of methicillin resistance (more than 80%). All of the S. auricularis, S. cohnii, S. caprae, S. lugdunensis and S. sciuri isolates were methicillin-susceptible.