Frequency of first and second-line drug resistance-associated mutations among resistant Mycobacterium tuberculosis clinical isolates from São Paulo, Brazil

BACKGROUND Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis, and the number of new cases of multidrug resistant TB (MDR-TB), pre extensively drug-resistant TB (pre-XDR-TB) and extensively drug-resistant TB (XDR-TB) has increased considerably worldwide. OBJECTIVES Herein, using 156 M. tuberculosis isolates from 106 patients previously classified as MDR or pre-XDR or XDR isolates, we investigated the genetic mutation profiles associated with phenotypic resistances in patients with MDR-TB, pre-XDR-TB and XDR-TB, treatment outcomes and resistance evolution. METHODS Molecular analyses were performed by partial sequencing of the rpoB, katG, gyrA, gyrB, rrs genes and analysis of the fabG-inhA promoter region. Clinical, epidemiologic and demographic data were obtained from the TB Notification database system of São Paulo (TB-WEB) and the Information System for Special Tuberculosis Treatments (SITE-TB). FINDINGS Drug resistance was attributed to previously known mutations and a novel Asp449Val mutation in gyrB was observed in four isolates from the same patient. Ten patients had more than one isolate evaluated and eight of these patients displayed resistance progression. MAIN CONCLUSIONS The present study is the first to report the frequency of mutations related to second-line drug resistance in MDR-TB, pre-XDR-TB and XDR-TB isolates. The results could lead to the improvement of available technologies for the rapid detection of drug resistant TB.

Bacteremia possibly caused by Curtobacterium spp found in a blood culture from a central venous line of a pediatric leukemia patient who underwent bone marrow transplantation: [letter to editor] / Bacteremia possivelmente causada por Curtobacterium spp encontrado na cultura do sangue de um cateter venoso num paciente pediátrico submetido a transplante de medula óssea: [carta ao editor]

Microbiologistas clínicos devem estar atentos à possibilidade debacteremia relacionada com cateter causada por infecçãodifteróide, como possivelmente foi o caso neste relato, no qual um menino de dois anos, portador de um cateter venoso central paratratamento de leucemia, apresentou pneumonia. A cultura dosangue obtido no cateter revelou Curtobacterium spp.

Laboratory detection methods for methicillin resistance in coagulase negative Staphylococcus isolated from ophthalmic infections

PURPOSE: To evaluate different methods of oxacillin susceptibility testing of ocular isolates, considering polymerase chain reaction (PCR) as the 'gold standard', and to compare the in vitro susceptibility to oxacillin with that of other antimicrobials used in ophthalmologic practice. METHODS: The Vitek gram-positive identification card was used to identify ocular coagulase negative Staphylococcus species. The presence of the mecA gene was determined by the polymerase chain reaction assay with a combination of two primer sets (mecA and 16S rRNA) in a single region. Results were analyzed and compared with other oxacillin susceptibility methods: PBP2a detection by rapid slide latex agglutination test (SLA); oxacillin E-test; the Vitek automated gram-positive susceptibility card (GPS-105); the oxacillin salt agar screening test (OSAS) at a concentration of 6.0, 1.0 and 0.75 æg oxacillin per ml and the cefoxitin disk diffusion test (CDD). Automated susceptibility was also determined to other antimicrobial agents (fluoroquinolones, penicillin G, amoxicillin-ampicillin, cefazolin, ampicillin-sulbactam, erythromycin, clindamycin, gentamicin, tetracycline, trimethoprim-sulfamethoxazole, vancomycin and rifampin. RESULTS: Of the 69 CoNS isolates tested, 71 percent were mecA-positive and 29 percent mecA-negative. All methods tested had a statistically significant agreement with polymerase chain reaction. There was a tendency of positive polymerase chain reaction predomination among the S. epidermidis isolates in comparison to non-epidermidis isolates, although this was not statistically significant (78.3 percent vs. 56.5 percent; chi2= 2.54; P= 0.11). The oxacillin salt agar screening test (0.75 æg oxacillin/ml) showed the best performance, with 100 percent sensitivity and negative predictive value; 95 percent specificity and 98 percent positive predictive value. Using the E-test, the mecA-positive isolates were statistically significantly more...

OBJETIVOS: Avaliar os diferentes métodos de suscetibilidade à oxacillina, em isolados oculares, considerando a reação em cadeia da polimerase (PCR) como "padrão-ouro" e comparar a suscetibilidade in vitro para outros antimicrobianos de uso oftalmológico. MÉTODOS: O sistema automatizado Vitek foi utilizado para identificar as diferentes espécies de Staphylococcus coagulase negativo (SCoN). A presença do gene mecA foi determinado pela reação em cadeia da polimerase com a combinação de 2 "primer" sets (mecA e 16S rRNA) em uma única região. Estes resultados foram analisados e comparados com outros métodos de suscetibilidade à oxacilina: detecção da proteína PBP2a pelo teste de aglutinação em látex (SLA); E-test oxacilina; o sistema automatizado Vitek (GPS-105); o teste de triagem em ágar (OSAS) com oxacilina nas concentrações de 6,0, 1,0 e 0,75 æg oxacilina por ml e o teste de disco difusão com cefoxitina (CDD). A suscetibilidade automatizada foi obtida para os seguintes agentes antimicrobianos: fluorquinolonas, penicilina G, amoxicilina-ampicilina, cefazolina, ampicilina-sulbactam, eritromicina, clindamicina, gentamicina, tetraciclina, sulfametoxazol-trimetoprima, vancomicina e rifampicina. RESULTADOS: Dos 69 Staphylococcus coagulase negativo testados, 71 por cento foram mecA-positivos e 29 por cento, mecA-negativos. Todos os métodos testados apresentaram concordância estatisticamente significante com a reação em cadeia da polimerase. Houve tendência à predominância da positividade da reação em cadeia da polimerase entre os S. epidermidis comparado aos não-epidermidis, embora sem significância estatistica (78,3 por cento vs. 56,5 por cento; chi2= 2,54; p=0,11). O teste de triagem em ágar (0,75 æg oxacilina/ml) apresentou a melhor performance com resultados de: 100 por cento de sensibilidade e valor preditivo negativo, 95 por cento de especificidade e 98 por cento de valor preditivo positivo. Os isolados mecA-positivos foram estatisticamente...