Outbreak caused by Enterobacteriaceae harboring NDM-1 metallo-ß-lactamase carried in an IncFII plasmid in a tertiary care hospital in Mexico City.

Carbapenem-resistant Enterobacteriaceae carrying New Delhi metallo-ß-lactamase 1 (NDM-1) have rarely been reported in Latin America. We report of an outbreak caused by a blaNDM-1-harboring plasmid spread through different bacterial species, including Escherichia coli (ST617) and Enterobacter cloacae (ST182) isolates from the same patient and three Klebsiella pneumoniae isolates (ST22) derived from three epidemiologically related patients. IncFII plasmids were found in all strains. Measures to control the outbreak were applied successfully.

Concordance between two enzyme immunoassays for the detection of Clostridium difficile toxins.

BACKGROUND AND AIMS: The diagnosis of Clostridium difficile-associated disease (CDAD) is based on the detection of toxins from stool samples. There are several immunoassays for this purpose. The aim of this study was to determine the concordance between the two immunoassays and their performance in comparison to the toxigenic culture as part of the initial evaluation of a suspected case of CDAD. METHODS: All fecal samples submitted for detection of C. difficile toxins during a 5-month period to our laboratory were analyzed by two immunoassays, VIDAS Toxin CDA/B assay (BioMerieux) and ImmunoCard Toxins A/B (Meridian Bioscience). We cultured on cycloserine-cefoxitin-fructose agar and PCR was used for detection of toxigenic genes. Real-time PCR was performed directly from samples to detect the tcdC gene. RESULTS: At the end of the study we processed 230 samples, 13 were positive using VIDAS CDA/B (5.6%), and 14 using ImmunoCard A/B (6.0%); kappa coefficient was 0.857. With ImmunoCard A/B we obtained a sensitivity of 80%, a specificity of 99%, positive predictive value (PPV) 86% and negative predictive value (NPV) 98%, as compared to toxigenic culture. For VIDAS CDA/B we obtained a sensitivity of 90%, a specificity of 98%, PPV 69% and NPV 99%, compared to the same standard. There were seven undetermined results (3.0%) by VIDAS CDA/B. Five of these had a positive culture and all the patients had symptoms of CDAD. Considering these undetermined results as positive, we calculated a sensitivity of 93%, specificity of 97%, PPV 71% and NPV of 99% for this test, and a kappa of 0.856. Both immunoassays showed similar results and are suitable for the initial evaluation of patients with suspected CDAD. CONCLUSIONS: Our data suggest that an undetermined result of VIDAS CDA/B should be considered as positive if CDAD is suspected. Additionally, both immunoassays showed similar results and are suitable for the initial evaluation of patients with suspected CDAD.

Renal tuberculosis.

BACKGROUND: tuberculosis (TB) is a disease with a high incidence and prevalence worldwide. Renal TB is the second most common extrapulmonary form of TB. The purpose of this report is to present the case of a patient with renal TB in order to emphasize the importance of this disease. CLINICAL CASE: we report the case of a 30-year-old female who presented with fever, cough, diaphoresis and an abdominal right flank mass. Right hydronephrosis, dilated collector system and loss of renal function were documented. A right nephrectomy was performed. Histopathological exam revealed acid-fast mycobacteria, granulomas and multinucleated Langhans-type giant cells. Renal TB was diagnosed and anti-TB treatment was initiated. CONCLUSIONS: renal TB is a disease whose incidence has increased in relation to the TB epidemic. Renal TB should be considered in the evaluation of renal masses.

[Efficacy and impact of polymerase chain reaction in the diagnosis of extrapulmonary tuberculosis]. / Eficacia e impacto de la prueba de la reacción en cadena de la polimerasa en el diagnóstico de tuberculosis extrapulmonar.

OBJECTIVE: To evaluate the efficacy of PCR in the diagnosis of extrapulmonary tuberculosis (TB) and its impact in the management of patients in a tertiary-care center in Mexico City. METHOD: We conducted a retrospective study based on 40 clinical charts of patients to whom nested PCR was performed for the diagnosis of TB from June 1999 to December 2000. We reviewed the medical notes of 10 days before and 10 days after the PCR study to analyze its impact in the management of the patient. Also, we reviewed the rest of the chart to decide if the patient suffered from TB or not (gold standard). The categories of diagnosis were definitive case of TB, probable TB and no TB. We calculated the sensitivity, specificity, and predictive values. RESULTS: The PCR was positive in 45% of the cases. The sensitivity of PCR to diagnosis TB was 50%, specificity 59%, and the positive and negative predictive value were 35% and 72%, respectively. If just spinal fluid was included, the sensitivity and the negative predictive value increased to 75% and 63%, respectively. The PCR had an impact in the management of 13% of the patients. CONCLUSIONS: The PCR for the diagnosis of extrapulmonary TB has limited efficacy, which improves when the test is done in spinal fluid samples. The impact of the result of PCR in the clinical management of the patients was poor.