Molecular epidemiology of invasive and non-invasive group B Streptococcus circulating in Serbia

Abstract

Streptococcus agalactiae (group B Streptococcus, GBS) remains the leading cause of invasive diseases in neonates and an important cause of infections in the elderly. The aim of this study was to access the prevalence of GBS genito-rectal colonisation of pregnant women and to evaluate the genetic characteristics of invasive and non-invasive GBS isolates recovered throughout Serbia.A total of 432 GBS isolates were tested for antimicrobial susceptibility, capsular polysaccharide (CPS) types and the presence of the hvgA gene. One hundred one randomly selected isolates were further characterized by clustered regularly interspaced short palindromic repeats (CRISPRs) analysis and/or multilocus sequence typing (MLST).The prevalence of GBS colonization in pregnant women was 15%. Overall, six capsular types (Ia, Ib, II to V) were identified, the most common being III (32.2%) and V (25.2%). The hiper-virulent clone type III/ST17 was present in 43.1% and 6.3% (p<0.05) of paediatric and adults isolates, respectively. Comparative sequence analysis of the CRISPR1 spacers content indicated that a few clones comprised the vast majority of the tested GBS isolates. Thus, it was estimated that dominant clones recovered from infants were CPS III/ST17 in late-onset infections (19/23; 82.6%), and Ia/ST23 in early-onset disease (44.4%). Conversely, genotype CPS V/ST1 was the most prevalent in adults (4/9; 25.4%). All isolates were susceptible to penicillin. Macrolide resistance (23.1%) was strongly associated with the ermB gene and constitutive resistance to clindamycin (63.9%). The majority of strains was resistant to tetracycline (86.6%), mostly mediated by the tetM gene (87.7%). GBS isolates of CPS V/ST1 and CPS III/ST23 were significantly associated with macrolide and tetracycline resistance, respectively.In conclusion, hyper-virulent CPS III/ST17 and V/ST1 were recognized as dominant GBS clones in this study.

Evaluation of the Results of Group B Streptococcus Screening by MALDI-TOF MS among Pregnant Women in a Hungarian Hospital

“…In our study, the GBS colonization level was found to be around 20% during the examined period. This value falls into the range of the colonization rates (i.e., from 6.5% to 36%) reported earlier for European countries [15,17], but it is somewhat higher than that reported recently in the neighboring country, Serbia (15%) [18]. At the same time, this relatively high colonization rate emphasizes the importance of the accurate GBS screening of pregnant women.…”

“…Our study also indicates a significant distribution of the ST-17 clone. Recently, Gajic et al [18] found this sequence type as the most common clone in Serbian samples. Moreover, the rate of erythromycin and clindamycin co-resistance was found to be extremely high among the ST-1 clones (52.1%).…”

“…At the same time, a high level of resistance to erythromycin and clindamycin, and a clearly increasing tendency in the frequency of resistant strains has been observed over the years examined. Other studies have also reported the spreading of macrolide and lincosamide resistance among the GBS strains [23][24][25], and highlighted the need of susceptibility testing of colonizing GBS strains for an effective intrapartum antibiotic prophylaxis [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The majority of erythromycin and clindamycin resistant strains proved to be co-resistant to these antibiotics, and the majority of the detected clindamycin resistances were constitutive.…”

Increasing Resistance and Changes in Distribution of Serotypes of Streptococcus agalactiae in Poland

“…Most of them were diagnosed with constitutive MLS B and ten times less with inducible MLS B . The constitutive MLS B mechanism was also the most commonly found mechanism of macrolide resistance by other authors in Poland [ 34 , 35 ], Serbia [ 30 ], Germany [ 36 ], and France [ 37 ]. Other groups of antibiotics were also assessed in this study.…”

“…During the last decades resistance to macrolides and lincosamides emerged. The percentages of strains resistant to erythromycin and clindamycin varied between European countries and were reported as 43.7% and 32.2% in Italy [ 17 ], 30.0% and 28.0% in Switzerland [ 29 ], 23.1% and 21.3% in Serbia [ 30 ], and 14.5% and 14.0% in Sweden [ 31 ]. Moreover, outside Europe, a worrying trend towards increasing resistance to these antibiotics group have been found, especially in China (78.6%–92.5% of strains resistant to erythromycin and 64.3%–87.5% resistant to clindamycin) [ 5 , 18 , 19 ].…”