National Multicentre Study of Streptococcus agalactiae invasive infections: antibiotic resistance and serotype distribution.

ARIAS B; KOVACEC V; SUAREZ M; VIGLIAROLO L; TERSIGNI C; MULLER L; SUTTICH E; LOPARDO H; BONOFIGLIO L; MOLLERACH M

Buenos Aires

Congreso; III International Congress in Translational Medicine; 2016

Introduction: S. agalactiae (group B streptococcus, GBS) is the leading cause of neonatal sepsis. In recent years an increase in the incidence of invasive infections in adult patients has been noticed. To determine the epidemiology of invasive infections in Argentina we designed a national prospective multicentre study during the July/2014-June/2015 period. This research provides information about GBS serotype distribution and antimicrobial susceptibility, which will allow the development of control strategies. Methods: For this study, 87 health centers from 32 cities participated and 162 isolates of invasive GBS were recovered. Clinical data of each patient were analyzed. Susceptibility to penicillin (PEN), erythromycin (ERY), clindamycin (CLI), lincomycin (LIN) and levofloxacin (LEV) was determined by disk diffusion method according to CLSI guidelines; for streptomycin (STR300) and gentamicin (GEN120) we used Enterococcus spp. breakpoints to detect high-level aminoglycoside (AG) resistance. Susceptibility to PEN was also explored using oxacillin (OXA), ceftibuten (CFB) and ceftizoxime (ZOX). In addition, the MICs to PEN, ERY, CLI, LEV, STR, GEN, OXA, CFB and ceftriaxone (CRO) were performed by the agar dilution method with sheep blood Mueller Hinton agar. Serotyping was performed by using the Strep B latex kit (Statens Serum Institut). Specific serotype PCR was used for the isolates with uncertain results or negative reaction. Results: GBS was mainly isolated from adults (77%, 125/162). GBS were recovered mainly from blood cultures, skin and soft tissues. Among patient with underlying disease (76/162), the most frequent was Diabetes mellitus (43/76). There were no significant differences on patient gender.There was no difference between disk diffusion and agar dilution results. All of the isolates were susceptible to PEN and CRO, 17.2% (28/162) were resistant to macrolides with 8% of this group express co-resistance to STR; 11% were highly-resistant to GEN and 6% to both AG. Resistance to LEV was 14.2%. Serotype III was prevalent followed by Ib, V, Ia and II.Conclusions: Respect to previous studies we detect an increase in the prevalence of GBS invasive infections in adults. PEN and CRO are still the drugs of choice for treating GBS infections. We found high rates of GBS resistant to macrolides. It is similar to that being reported in other countries; therefore it is advisable to routinely perform the disk diffusion test with macrolide disks. The high-level AG resistance percentage is a matter of real concern; its association with macrolides resistance was previously reported in our country. We alert about GBS isolates resistant to LEV, mostly of serotype Ib. The serotype distribution found is different to that reported from other areas of Latin-America. Knowledge of the antimicrobial resistance pattern of GBS is an important tool to guide empiric treatments and to avoid clinical complications.