Evaluation of constitutive and inducible resistance to clindamycin in clinical samples of Staphylococcus aureus from a tertiary hospital

• Published in: Revista da Sociedade Brasileira de Medicina Tropical
• Main Authors: Angelita Bottega, Mônica de Abreu Rodrigues, Fernanda Aguirre Carvalho, Tatiana Feyh Wagner, Isabel Agne Souza Leal, Silvana Oliveira dos Santos, Roberta Filipini Rampelotto, Rosmari Hörner
• Format: Article in Journal/Newspaper
• Language: English
• Published: Sociedade Brasileira de Medicina Tropical (SBMT) 2014
• Subjects: Methicillin-resistant Staphylococcus aureus; Methicillin-susceptible Staphylococcus aureus; D-test; Clindamycin bacterial resistance; Arctic medicine. Tropical medicine; RC955-962; Arctic
• Online Access: https://doi.org/10.1590/0037-8682-0140-2014; https://doaj.org/article/029a9c99174545e087be409e318c030b

Introduction Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have become common in hospitals and the community environment, and this wide resistance has limited patient treatment. Clindamycin (CL) represents an important alternative therapy for infections caused by S. aureus. Antimicrobial susceptibility testing using standard methods may not detect inducible CL resistance. This study was performed to detect the phenotypes of resistance to macrolides-lincosamides-streptogramin B (MLSB) antibiotics, including CL, in clinical samples of S. aureus from patients at a tertiary hospital in Santa Maria, State of Rio Grande do Sul, Brazil. Methods One hundred and forty clinical isolates were submitted to the disk diffusion induction test (D-test) with an erythromycin (ER) disk positioned at a distance of 20mm from a CL disk. The results were interpreted according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI). Results In this study, 29 (20.7%) of the 140 S. aureus samples were resistant to methicillin (MRSA), and 111 (79.3%) were susceptible to methicillin (MSSA). The constitutive resistance phenotype (cMLSB) was observed in 20 (14.3%) MRSA samples and in 5 (3.6%) MSSA samples, whereas the inducible resistance phenotype (iMLSB) was observed in 3 (2.1%) MRSA samples and in 8 (5.8%) MSSA samples. Conclusions The D-test is essential for detecting the iMLSB phenotype because the early identification of this phenotype allows clinicians to choose an appropriate treatment for patients. Furthermore, this test is simple, easy to perform and inexpensive.