RESUMEN
BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen frequently isolated in both hospital and community environments. Methicillin-resistant Staphylococcus aureus is considered a major nosocomial pathogen that causes severe morbidity and mortality. OBJECTIVES: The main objective of this study was to determine the genotypes of MRSA strains isolated from the nares of hospitalized and community patients in Kermanshah Hospital, western Iran, by PCR-restriction fragment length polymorphism (PCR-RFLP). MATERIALS AND METHODS: Of 1387 patients, 1217 patients were screened for more than 48 hours after admission in hospital wards and 170 patients were screened in the hemodialysis unit of Kermanshah Hospital, which is the largest hospital in western Iran. S. aureus was identified by standard biochemical tests, including colonial morphology, production of coagulase, and DNase and the API20 Staph test. Methicillin-resistant Staphylococcus aureus was identified by the Oxacillin strip test. RESULTS: In total, 258 S. aureus isolates were recovered from 1387 samples, of which 96 isolates were MRSA, 82 were hospital acquired, and 14 were community acquired. Digestion of the aro A gene revealed only one distinctive RFLP pattern in the 258 isolates. CONCLUSIONS: Methicillin-resistant Staphylococcus aureus is an increasingly common cause of nosocomial infections. Our results are in agreement with those of other studies reporting that a few specialized clones are responsible for most cases of MRSA nasal carriage. In this study, MRSA strains isolated from different wards of hospital were closely related when analyzed by coagulase gene typing. Identifying patients colonized with MRSA during hospitalization and rapidly typing them with these methods may facilitate detection of outbreaks and prevention of the spread of organisms in hospitals.
RESUMEN
BACKGROUND AND OBJECTIVE: Tuberculosis (TB) is a devastating infectious disease causing high mortality and morbidity worldwide. The most serious threat related to tuberculosis control is the recent emergence of drug-resistant tuberculosis strains. The aim of the present study was to identify various types of mutations in the rpoB region in rifampicin-resistant strains isolated from sputum of tuberculosis patients. MATERIALS AND METHODS: Drug susceptibility of 125 Mycobacterium tuberculosis isolates was determined using the CDC standard conventional proportional method. Target DNA of M. tuberculosis was amplified by polymerase chain reaction, hybridized, and scanned. We used the low cost density array (LCD-array) to detect mutations within the 90-bp rpoB region. Each array is a transparent, prestructured polymer support using a nonfluorescent detection principle based on the precipitation of a clearly visible dark substrate. RESULTS: Of the 125 M. tuberculosis isolates, 35 (28%) were found to be rifampicin-resistant and using the LCD array revealed point mutations at nine different codons as follows: S512T (AGCâACC) (20%), D516V (GACâGTC) (20%), H526D (CACâGAC) (6%), H526R (CACâCGC) (20%), H526Y (CACâTAC) (23%), and S531W (TCGâTGG) (8%), and the most frequent site mutations were L511P (CCGâCTG) (46%), followed by S531l (TCGâTTG) (40%) and D516Y (GACâTAC) (26%). CONCLUSION: Our data significantly differs from previously reported mutation frequencies for codon 526 (CAC to GAC) among Italian isolates (40.1%) and Greek isolates (17.6%). Phenotypic testing is time-consuming and requires laboratory resources. Microarray rpoB is useful in detecting rifampicin resistance-determining region-associated site mutations of rifampicin-resistant M. tuberculosis isolates.
Asunto(s)
Antituberculosos/farmacología , Proteínas Bacterianas/genética , Tuberculosis Extensivamente Resistente a Drogas/epidemiología , Tasa de Mutación , Mycobacterium tuberculosis/efectos de los fármacos , Rifampin/farmacología , Tuberculosis Pulmonar/epidemiología , Adulto , Codón , ARN Polimerasas Dirigidas por ADN , Farmacorresistencia Bacteriana/genética , Tuberculosis Extensivamente Resistente a Drogas/tratamiento farmacológico , Tuberculosis Extensivamente Resistente a Drogas/microbiología , Femenino , Expresión Génica , Humanos , Incidencia , Irán/epidemiología , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/aislamiento & purificación , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Esputo/microbiología , Tuberculosis Pulmonar/tratamiento farmacológico , Tuberculosis Pulmonar/microbiologíaRESUMEN
BACKGROUND AND OBJECTIVE: Mycobacterium tuberculosis has developed resistance to antituberculosis drugs and becoming a major and alarming public health problem in worldwide. This study was aimed to determine antituberculosis drug resistance rate and to identify multidrug resistant tuberculosis (MDR-TB) in West of Iran. MATERIALS AND METHODS: Of 130 samples were included between December 2011 and July 2012 in the study from that 112 cases were M. tuberculosis. The proportional method was carried out according to the Clinical and Laboratory Standards Institute on Lowenstein-Jensen against isoniazid, rifampicin, streptomycin, ethambutol, pyrazinamide, para aminosalicylic acid, ethionamide, cycloserine (CYC). The microdilution method was carried out using 7H9 broth with 96 well-plates. RESULTS: From 112 isolates, resistance was observed to isoniazid 18 (16.07%), rifampicin 16 (14.28%), streptomycin 25 (22.32%), ethambutol 15 (13.39%), pyrazinamide 27 (24.10%), para aminosalicylic acid 19 (16.96%), CYC 4 (3.57%), and ethionamide 14 (12.5%) cases. 16 isolates were MDR. CONCLUSION: The high prevalence of MDR-TB in our study is assumed to be due to recent transmission of drug-resistant strains. Overall, the rate of drug resistance in our study was high, which is in line with findings of some high-burden countries. Hence that early case detection, rapid drug susceptibility testing, and effective anti-TB treatment is necessary.