TITLE:
Study of Serotypes, Susceptibility to Macrolide and Virulence and Resistance Molecular Profiles in Invasive Strains of Streptococcus agalactiae in Two Argentine Provinces
AUTHORS:
Margarita Laczeski, Marina Novosak, Roxana Cannistraci Giolito, Ana Littvik, Jorge Paván, Viviana Villalba, Marta Vergara
KEYWORDS:
Streptococcus agalactiae, Perinatal Infection, Macrolides, Resistence Genes, Virulence Genes
JOURNAL NAME:
Advances in Microbiology,
Vol.5 No.4,
April
9,
2015
ABSTRACT: 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 by E-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.