Outbreak of Vibrio cholerae serogroup O1, serotype Ogawa, biotype El Tor strain--La Huasteca Region, Mexico, 2013.

On September 2 and 6, 2013, Mexico's National System of Epidemiological Surveillance identified two cases of cholera in Mexico City. Rectal swab cultures from both patients were confirmed as toxigenic Vibrio cholerae serogroup O1, serotype Ogawa, biotype El Tor. Pulsed-field gel electrophoresis and virulence gene amplification (ctxA, ctxB, zot, and ace) demonstrated that the strains were identical to one another but different from strains circulating in Mexico previously. The strains were indistinguishable from the strain that has caused outbreaks in Haiti, the Dominican Republic, and Cuba. The strain was susceptible to doxycycline, had intermediate susceptibility to ampicillin and chloramphenicol, was less than fully susceptible to ciprofloxacin, and was resistant to furazolidone and trimethoprim-sulfamethoxazole. An investigation failed to identify a common source of infection, additional cases, or any epidemiologic link between the cases. Both patients were treated with a single, 300-mg dose of doxycycline, and their symptoms resolved.

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

A total of 221 strains of Aeromonas species isolated in Mexico from clinical (161), environmental (40), and food (20) samples were identified using the automated system bioMérieux-Vitek®. Antisera for serogroups O1 to 044 were tested using the Shimada and Sakazaki scheme. The K1 antigen was examined using as antiserum the O7:K1C of Escherichia coli. Besides, we studied the antimicrobial patterns according to Vitek AutoMicrobic system. Among the 161 clinical strains 60 percent were identified as A. hydrophila, 20.4 percent as A. caviae, and 19.25 percent as A. veronii biovar sobria. Only A. hydrophila and A. veronii biovar sobria were found in food (55 and 90 percent respectively) and environmental sources (45 and 10 percent respectively). Using "O" antisera, only 42.5 percent (94/221) of the strains were serologically identified, 55 percent (121/221) were non-typable, and 2.5 percent (6/221) were rough strains. Twenty-two different serogroups were found, O14, O16, O19, O22, and O34 represented 60 percent of the serotyped strains. More than 50 percent of Aeromonas strain examined (112/221) expressed K1 encapsulating antigen; this characteristic was predominant among Aeromonas strains of clinical origin. Resistance to ampicillin/sulbactam and cephazolin was detected in 100 and 67 percent of Aeromonas strain tested for their susceptibility to antibiotics. In conclusion, antibiotic-resistant Aeromonas species that possess the K1 encapsulating antigen and represent serogroups associated with clinical syndrome in man are not uncommon among Aeromonas strains isolated from clinical, food and environmental sources in Mexico.

Survival of Brucella abortus in milk fermented with a yoghurt starter culture.

In countries such as Mexico, brucellosis is still an important public health problem due to the consumption of non-pasteurized milk and dairy products, contaminated with Brucella spp. The aim of this study was to look into the survival of Brucella abortus during fermentation of milk with a yoghurt starter culture and storage at refrigeration temperature. Sterile skim milk was inoculated with B. abortus at two concentrations, 10(5) and 10(8) CFU/ml simultaneously with a yoghurt starter culture of lactic acid bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii subspecie bulgaricus). Inoculated flasks were incubated at 42 degrees C, followed by refrigeration at 4 degrees C. Samples were taken during fermentation and during storage and viable count of B. abortus and lactic acid bacteria and pH were determined. Results showed that after 10 days of storage at 4 degrees C, B. abortus was recovered in fermented milk at a level of 10(5) CFU/ml, despite the low pH below 4.0. Therefore B. abortus is able to survive in fermented milk. This finding may imply that non-pasteurized fermented milk contaminated with Brucella abortus could be a means of transmission of these bacteria.