Susceptibility to chlorhexidine and mupirocin among methicillin-resistant Staphylococcus aureus clinical isolates from a teaching hospital.

Despite the widespread use of chlorhexidine (CHX) to prevent infection, data regarding the in vitro action of CHX against methicillin-resistant Staphylococcus aureus (MRSA) are limited. Clinical isolates from Hospital das Clinicas, Sao Paulo, Brazil, identified during 2002/2003 and 2012/2013 were studied to describe the susceptibility to CHX and mupirocin, molecular characteristics, and virulence profile of MRSA. Susceptibility test to Mupirocin was performed by the disk diffusion method and to CHX by the agar dilution technique. PCR for virulence genes, mecA gene and Staphylococcal Cassette Chromosome mec (SCCmec) types were investigated as well. Mupirocin- and CHX-resistant isolates were sequenced using the IlluminaTM plataform. Two hundred and sixteen MRSA clinical isolates were evaluated: 154 from infected and 62 from colonized patients. Resistance to mupirocin was observed in four isolates assigned as SCCmec type III and STs (ST05; ST239 and ST105) carrying mupA and blaZ, two of them co-harboring the ileS gene. Only one isolate assigned as SCCmec type III was resistant to CHX (MIC of 8.0 µg.mL-1) and harbored the qacA gene. Resistance to chlorhexidine and mupirocin were found in isolates carrying qacA and mupA in our hospital. Since these genes are plasmid-mediated, this finding draws attention to the potential spread of resistance to mupirocin in our hospital.

Prevalence of methicillin-resistant Staphylococcus aureus colonization in individuals from the community in the city of Sao Paulo, Brazil.

Staphylococcus aureus (SA) is a commensal habitant of nasal cavities and skin. Colonization by community-acquired methicillin-resistant SA (CA-MRSA) is associated with infections in patients who have not been recently hospitalized. The aim of this study is to determine the prevalence of MRSA colonization in an outpatient population, currently unknown in Brazil. Three-hundred patients or caregivers from two teaching hospitals were included. A questionnaire was applied and nasal swabs were obtained from patients. Swabs were inoculated in brain heart infusion (BHI) with 2.5% NaCl and seeded in mannitol. Suspicious colonies were subjected to MALDI-TOF MS Microflex™ identification. Antimicrobial susceptibility test for oxacillin was performed for SA-positive samples by microdilution. Polymerase chain-reactions for detection of mecA and coA genes were performed for resistant samples. Data about MRSA carriers were compared with non-carriers. There were 127 S. aureus isolates, confirmed by MALDI-TOF. Only seven (2.3%) were MRSA and positive for mecA and coA genes. Factors associated with MRSA carriage were African ethnicity, skin diseases or antibiotic use. The majority of them were from Dermatology clinics. Prevalence of MRSA colonization in individuals from the community was low in our study (2.3%). This finding raises the hypothesis of inter-household transmission of SA, although we did not find any association between MRSA-colonization and the shared use of personal objects. Given the low prevalence of MRSA carriers observed, empirical antimicrobial coverage for MRSA in community-acquired infections should be not necessary.

Diagnostico Etiológico en Enfermedades Infecciosas

Background: The finding of a disease etiology is achieved through a wide range of laboratory tests with different sensitivity and specificity, and also subject to the availability in time and space to carry them. The most requested laboratory samples in infectious diseases are growing and cytochemical analysis of body fluids. We studied 300 medical records of patients admitted to the Adult Infectious Disease Service of the Institute of Tropical Medicine from January to November 2010, of which: 37.3% were respiratory infections, gastrointestinal infections and 34.3% 28 4% CNS infections. Ratio F: M 1:1.29 (56% F). The microbiological diagnosis was positive in 32%, 28% and 27% of patients with diseases of the respiratory Rev, Rev Gastrointestinal and CNS involvement, respectively, and the most common germs S. pneumoniae, C. and C. parvum neoformans in the order listed previously

El hallazgo etiológico de una enfermedad se logra gracias a una amplia gama de exámenes laboratoriales con diferentes valores de sensibilidad y especificidad, y también condicionados a la disponibilidad en el tiempo y espacio para la realización de los mismos. Las muestras de laboratorio más solicitadas en patologías infecciosas son: cultivo y análisis citoquímico de fluidos corporales. Se estudiaron 300 historias clínicas de pacientes internados en el Servicio de Infectología de Adultos del Instituto de Medicina Tropical de enero a noviembre del año 2010, de los cuales: 37,3 % correspondieron a infecciones respiratorias; 34,3% infecciones gastrointestinales y 28,4% infecciones del SNC. Relación F:M 1:1,29 (56% F). El diagnóstico microbiológico fue positivo en 32%, 28% y 27% de los pacientes con patologías del Ap. respiratorio, Ap. Gastrointestinal y con afectación del SNC respectivamente, y los gérmenes más frecuentes S. pneumoniae, C. parvum y C. neoformans en el orden citado previamente.