Nontuberculous mycobacteria in clinical samples with negative acid-fast bacilli.

BACKGROUND: There is a progressive increase in nontuberculous mycobacteria (NTM) in pulmonary and extrapulmonary infections that might cause confusion with the Mycobacterium tuberculosis complex. To determine the frequency of finding NTM in clinical samples from patients diagnosed with active tuberculosis, with negative acid-alcohol-resistant bacilli (acid-fast bacillus [AFB]) in a third-level specialty hospital's mycobacterial laboratory between January 2013 and December 2014. METHODS: This is a prospective, descriptive study where isolated strains of biological material were studied in Lowenstein-Jensen and BACTEC MGIT 960 cultures. RESULTS: Clinical samples of 120 patients were studied, with pulmonary samples of 99/120 (82%) and extrapulmonary samples of 21/120 (18%). We identified NTM in 37/120 samples (30.8%), of which 16 in pulmonary, 13 in genitourinary, 3 in bone marrow, and 5 in various specimens. Mycobacterium avium was isolated in 20 samples, Mycobacterium intracellulare in seven samples, and various other species of NTM in the other 10 samples. CONCLUSION: To establish adequate treatment, we point out the importance of identifying the presence of NTM in the clinical samples of active tuberculosis patients with negative AFB, as possibly becoming confused with M. tuberculosis and which is essential in deciding which treatment is the most adequate.

[Outbreak caused by Escherichia coli in Chalco, Mexico]. / Brote causado por Escherichia coli en Chalco, México.

OBJECTIVE: To identify the etiologic agent responsible for a disease outbreak following an overflow of sewage water in Valle de Chalco, Mexico. MATERIAL AND METHODS: A retrospective cross-sectional study was carried out. Rectal samples were collected from the population of Chalco valley, who suffered from diarrhea and vomiting during a natural disaster that took place on May 31, 2000. The Instituto de Diagnóstico y Referencia Epidemiológicos (Epidemic Reference and Diagnosis Institute, InDRE, Ministry of Health), received 1521 rectal swab samples from diarrhea cases, to test for E. coli strains. Statistical analysis was performed to find a difference of proportions between cases and non-cases (chi-squared test). ETEC, EIEC, EPEC and EHEC pathogenic E. coli groups were hybridized by colony blot. RESULTS: Strains isolated were ETEC (62.2%), EIEC (0.84%), EPEC (0.84%), and EHEC non-O157:H7 (0.08%); there was no hybridization in 36.02% of E. coli strains. Other isolated microorganisms were Salmonella spp (0.45%) and Shigella spp (0.06%). CONCLUSIONS: Enterotoxigenic E. coli was the most likely etiologic agent. Sanitary control strategies should be targeted to preventing outbreaks caused by this pathogenic agent. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

Brote causado por Escherichia coli en Chalco, México / Outbreak caused by Escherichia coli in Chalco, Mexico

OBJECTIVE: To identify the etiologic agent responsible for a disease outbreak following an overflow of sewage water in Valle de Chalco, Mexico. MATERIAL AND METHODS: A retrospective cross-sectional study was carried out. Rectal samples were collected from the population of Chalco valley, who suffered from diarrhea and vomiting during a natural disaster that took place on May 31, 2000. The Instituto de Diagnóstico y Referencia Epidemiológicos (Epidemic Reference and Diagnosis Institute, InDRE, Ministry of Health), received 1521 rectal swab samples from diarrhea cases, to test for E. coli strains. Statistical analysis was performed to find a difference of proportions between cases and non-cases (chi-squared test). ETEC, EIEC, EPEC and EHEC pathogenic E. coli groups were hybridized by colony blot. RESULTS: Strains isolated were ETEC (62.2), EIEC (0.84), EPEC (0.84), and EHEC non-O157:H7 (0.08); there was no hybridization in 36.02 of E. coli strains. Other isolated microorganisms were Salmonella spp (0.45) and Shigella spp (0.06). CONCLUSIONS: Enterotoxigenic E. coli was the most likely etiologic agent. Sanitary control strategies should be targeted to preventing outbreaks caused by this pathogenic agent.