Phenotypic and molecular characterization of resistance to macrolides, lincosamides and type B streptogramin of clinical isolates of Staphylococcus spp. of a university hospital in Recife, Pernambuco, Brazil.
BACKGROUND
There is a mechanism of macrolide resistance in Staphylococcus spp. which also affects the lincosamides and type B streptogramins characterizing the so-called MLSB resistance, whose expression can be constitutive (cMLSB) or inducible (iMLSB) and is encoded mainly by ermA and ermC genes. The cMLSB resistance is easily detected by susceptibility testing used in the laboratory routine, but iMLSB resistance is not. Therapy with clindamycin in cases of infection with isolated iMLSB resistance may fail.


OBJECTIVE
To characterize the phenotypic (occurrence of cMLSB and iMLSB phenotypes) and molecular (occurrence of ermA and ermC genes) profiles of MLSB resistance of clinical isolates of susceptible and methicillin-resistant Staphylococcus aureus and CNS (coagulase-negative Staphylococcus) from patients of a university hospital, in Pernambuco.


METHODS
The antimicrobial susceptibility of 103 isolates was determined by the disk diffusion technique in Mueller-Hinton agar followed by oxacillin screening. The iMLSB phenotype was detected by D test. Isolates with cMLSB and iMLSB phenotypes were subjected to polymerase chain reaction (PCR) for the detection of ermA and ermC genes.


RESULTS
The cMLSB and iMLSB phenotypes were respectively identified in 39 (37.9%) and five (4.9%) isolates. The iMLSB phenotype was found only in four (10.8%) methicillin-susceptible S. aureus and one (4.5%) methicillin-resistant S. aureus. In the 44 isolates subjected to PCR, four (9.1%) only ermA gene was detected, a lower frequency when compared to only ermC 17 (38.6%) gene and to one (2.3%) isolate presenting both genes.


CONCLUSIONS
In the Staphylococcus spp. analyzed, the ermC gene was found more often than the ermA, although the iMLSB phenotype had been less frequent than the cMLSB. It was important to perform the D test for its detection to guide therapeutic approaches.
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil. Electronic address: ju-biomed@hotmail.com.
Jussyêgles Niedja da Paz
JN
Pereira
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Marcelle Aquino
MA
Rabelo
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Jailton Lobo da Costa
JL
Lima
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Armando Monteiro Bezerra
AM
Neto
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Ana Catarina de Souza
AC
Lopes
Department of Tropical Medicine, Universidade Federal de Pernambuco, Recife, PE, Brasil.
Maria Amélia Vieira
MA
Maciel
D001938:Brazil; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D006785:Hospitals, University; D006801:Humans; D055231:Lincosamides / Q000494:pharmacology*; D018942:Macrolides / Q000494:pharmacology*; D010641:Phenotype; D013210:Staphylococcus / Q000187:drug effects* / Q000235:genetics*; D025381:Streptogramin B / Q000494:pharmacology*
D055231:Lincosamides; D018942:Macrolides; D025381:Streptogramin B
Clindamycin; Inducible resistance; Staphylococcus; erm genes