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.

Serotypes of Vibrio cholerae non-O1 isolated from water supplies for human consumption in Campeche, México and their antibiotic susceptibility pattern

The presence of Vibrio cholerae non-O1 in water supplies for human consumption in the city of Campeche and rural locality of Becal was investigated. V. cholerae non-O1 was detected in 5.9 per cent of the samples obtained in deep pools of Campeche. Studies conducted in Becal and neighbourhood of Morelos in Campeche indicated that collected samples harbored V. cholerae non-O1 in 31.5 per cent and 8.7 per cent respectively. There was a particular pattern of distribution of V. cholerae non-O1 serotypes among different studied regions. Accordingly, V. cholerae non-O1 serotype O14 predominated in the deep pools of Campeche and together with V. cholerae non-O1, O155 were preferentially founds in samples taken from intradomiciliary faucets in the neighbourhood of Morelos. Samples from Becal predominantly presented the serotype O112. 60 per cent and 53.8 per cent of all studied strains of V. cholerae non-O1 proved to be resistant to amplicillin and carbenicillin. 3.1 per cent, 7.7 per cent and 6.2 per cent presented resistant to doxycycline, trimethroprim-sulfamethoxale and erythromycin respectively. The study showed the necessity of performing a strong epidemiologic surveillance for emergence and distribution of V. cholerae non-O1.