Study of Serotypes, Susceptibility to Macrolide and Virulence and Resistance Molecular Profiles in Invasive Strains of Streptococcus agalactiae in Two Argentine Provinces

LACZESKI M, NOVOSAK M, CANNISTRACI GIOLITO R, LITTVIK A, PAVAN J, VILLALBA V, VERGARA M

Advances in Microbiology

Scientific Research Publishing

Año: 2015 vol. 5 p. 230 - 243

2165-3402

A study of invasive strains of Streptococcus agalactiae (GBS) from Cordoba and Misiones, Argentina;was conducted to determine serotypes, the susceptibility to macrolides and molecular profiles of virulence and resistance. We studied 17 strains, recovered from cerebrospinal fluid, blood and cellulite and, a strain of trophoblastic remnants from Misiones. The serotypes were determined by agglutination with sera and phenotypes of resistance to macrolide-lincosamide-streptogramin B(MLSB), were determined with the double-disk test (D-test). The confirmation was performed byE-test by ERI and CLI respectively that determined the minimum inhibitory concentration (MIC). Results were interpreted as recommended by the Clinical and Laboratory Standards Institute (CLSI) 2013. Resistance genes: ermB, ermTR and mefA and the virulence genes: bac, bca, rib, lmb, hylB,scpB, fbsA, fbsB and cylB were investigated by conventional PCR. Serotype III (50%) and Ia (50%)were detected in Cordoba. One strain showed cMLSB phenotype, confirmed by MIC. The same strains showed a resistance gene ermB. All studied virulence genes were detected in 100% of these strains. In Misiones, serotypes were III (72.7%), Ia (18.2%) and Ib (9.1%). All strains were susceptible to CLI and ERI by D-test, confirmed by MIC. None of the strains showed resistance genes. Virulence genes bca, rib, hylB, lmb, fbsA, fbsB and cylB were detected in 100% of the strains, bac in 81.8% and scpB in 90.9%. Our results are in accordance with international data, associating higher frequency of serotype III of invasive neonatal disease followed by Ia. The presence of serotype Ib could indicate a regional difference for Misiones. We highlight the macrolides susceptibility in strains of Misiones and consistency in the results for D-test, MIC and PCR for the single strain resistant phenotype cMLSB from Cordoba. The virulence genes studied were presented with high frequency as expected for invasive strains.