Streptococcus anginosus (milleri) Group Strains Isolated in Poland (1996–2012) and their Antibiotic Resistance Patterns

Abstract

A b s t r a c tStreptococcus anginosus, Streptococcus intermedius and Streptococcus constellatus form a group of related streptococcal species, namely the Streptococcus Anginosus Group (SAG). The group, previously called "milleri" had been rarely described until 1980/1990 as source of infections. Nowadays SAG bacteria are often described as pathogens causing predominantly purulent infections. The number of infec tions is highly underestimated, as SAG strains are often classified in the microbiology laboratory as less virulent "viridans streptococci". Epidemiological situation regarding SAG infections in Poland has been unrecognized, therefore we performed a retrospective analysis of strains isolated between 1996 and 2012. Strains suspected of belonging to SAG were reidentified using an automated biochemical approach (Vitek2) and MALDITOF MS. We performed first analysis of antibiotic resistance among SAG strains isolated in Poland using automated methods (Vitek2), disk diffusion tests and ETests. We also performed PCR detection of resistance determinants in antibiotic resistant strains. Clonal structure of analyzed strains was evaluated with PFGE and MLVF methods. All three species are difficult to distinguish using automated diagnostic methods and the same is true for automated MIC evaluation. Our analysis revealed SAG strains are rarely isolated in Poland, predominantly from purulent infections. All isolates are very diverse on the genomic level as estimated by PFGE and MLVF analyses. All analyzed strains are sensitive to penicillin, a substantial group of strains is resistant to macrolides and the majority of strains are resistant to tetracycline. K e y w o r d s:

Complicated Pneumonia With Empyema Caused by Streptococcus Anginosus in a Child

“…6,14,15 Empyema in the fibrinopurulent or organizing stage should be considered an indication for surgical management. 16 The antibiotic course is usually long, with a mean duration of up to 34 days, and most SAG isolates seem to be sensitive to penicillin and cefotaxime, 10,17,18 like in our case report. Some reports indicate that patients infected by S. anginosus can be co-infected by other agents, including anaerobes, so clindamycin was added at the begin of the treatment.…”

Efficient construction of Streptococcus anginosus mutants in strains of clinical origin

“…To check if the synthetic CSP was functional, we tested its activity on 17 other SAG strains from our collection (Obszanska et al 2016). Two-hour cultures were divided into three separate samples.…”

“…Escherichia coli DH5α was grown in liquid LB broth with aeration or on agar-solidified LB plates at 37°C. SAG strains used in these studies were described previously (Obszanska et al 2016) and strain 4194/05_Camp was generated during this study. SAG strains were grown in BHI (Brain Heart Infusion, Oxoid) liquid medium, on BHI blood agar plates or Columbia plates with 5% sheep blood (Becton Dickinson) in the presence of 5% CO 2 at 37°C.…”

“…SAG are oral bacteria, for years regarded as non-pathogenic viridans streptococci. However, in recent years, increased number of infections caused by these bacteria has been described (Obszanska et al 2016;Sitkiewicz 2018).…”

How to become a killer, or is it all accidental? Virulence strategies in oral streptococci

“…For years, the majority of the published material about SAG consisted of case reports, describing purulent infections. Recent analyses suggest that the number of infections caused by SAG is heavily underestimated . New data estimate the incidence of invasive SAG infections to be 8.65/100 000 population and 8.8/10 000 among hospitalized patients, which is markedly higher even than invasive GAS infections .…”