Susceptibilidad antimicrobiana y patrones de resistencia de Staphylococcus aureus aislados de pacientes y portadores en la ciudad de Valdivia, Chile / Antimicrobial susceptibility and resistance patterns of Staphylococcus aureus isolated from patients and carriers in Valdivia city, Chile

La susceptibilidad in vitro de Staphylococcus aureus adquirido, tanto en el ambiente hospitalario como en la comunidad, debe ser monitorizada periódicamente por su continua evolución. Objetivos: Conocer la susceptibilidad antimicrobiana de cepas de S. aureus aisladas en Valdivia, determinar la prevalencia de cepas resistentes a meticilina y sus respectivos patrones de resistencia, analizar la evolución de esta susceptibilidad a través de los años. Material y Métodos: Se evaluaron 278 cepas de S. aureus: 136 obtenidas de pacientes hospitalizados, 50 de pacientes ambulatorios y 92 de portadores. Los antimicrobianos ensayados fueron: penicilina, oxacilina, vancomicina, gentamicina, ciprofloxacina, lincomicina y eritromicina.

In vitro susceptibility of nosocomial and community acquired strains of Staphylococcus aureus must be periodically evaluated because of its continuous evolution. Aim: To know the antimicrobial susceptibility of S. aureus isolated in Valdivia, to determine the prevalence of methicillin resistance and global patterns of resistance and to compare the evolution of the susceptibility along the years. Material and Methods: A total of 278 S. aureus strains were evaluated: 136 obtained from hospitalized patients, 50 belonged to outpatients and 92 to healthy carriers. Antimicrobial agents tested were: penicillin, oxacillin, vancomycin, gentamycin, ciprofloxacin, lincomycin and erythromycin. Results: Thirty three, 28 and 1.1 percent of strains isolated from hospitalized, outpatients and carriers, respectively, were methicillin-resistant. Six resistance patterns were found. No vancomycin resistant strain was isolated. Comment: It is worrisome that 2 percent of S. aureus strains obtained from hospitalized patients showed intermediate resistance to vancomycin.

Genotipos de Staphylococcus aureus con fenotipo meticilino resistente, aislados de pacientes del Hospital Base de Valdivia / Genotypes of Staphylococcus aureus strains with methicillin resistant phenotype

Background: Methicillin resistant strains of Staphylococcus aureus (MRSA) are an important cause of nosocomial infections. Aim: To determine the genotypes of MRSA strains. Material and methods: Fifty five strains of MRSA, isolated from patients hospitalized in Hospital Base Valdivia, were studied. The phenotype was determined through MicroScan® in all strains and by minimum inhibitory concentration (MIC) in 41. The genotype of the strains was analyzed by a duplex polymerase chain reaction (PCR) of the mecA gene, amplifying eight hypervariable DNA regions associated to such gene. Results: According to MIC, 88 percent of strains had a pattern of resistance against multiple antimicrobial (penicillin, ampicillin, cephradine, gentamycin, ciprofloxacin, íincomycin and erythromycin). Vancomicin resistan strains were not detected. Only 53 strains (96 percent) had at least one of the eight hypervariable regions and were classified as MRSA. Genotypic patterns types 15 were the most commonly detected in 38 percent and 34 percent of strains, respectively. MicroScan® erroneously classified five strains in an incorrect phenotype, according to results obtained with duplex PCR. MIC results did not differ from those of duplex PCR. Conclusions: Duplex- PCR is a useful tool to detect hyper variable regions associated to mecA gene.

Detección de Chlamydia trachomatis en muestras uretrales mediante inmunofluorescencia directa / Detection of Chlamydia trachomatis in urethral samples by means of direct immunofluorescence

Em 82 doentes com uretrite foi pesquisada a presença de Chlamydia trachomatis, utilizando a prova da imunofluorescência direta, e de Neisseria gonorrhoeae, Mycoplasma e Ureaplasma, utilizando os métodos padröes. Ch trachomatis foi encontrada em 19.5 dos casos, sendo que em 11 deles (68,8) observou-se associaçäo entre Chlamydia e as outras bactérias pesquisadas. Nesses pacientes observou-se presença de secreçäo uretral escassa e de aspecto gelatinoso