Determinants of Virulence and Antimicrobial Susceptibility in Non-O1, Non-O139 Vibrio cholerae Isolates

ABSTRACT INTRODUCTION In the Caribbean region, acute diarrheal diseases caused by the Vibrio genus have increased in recent years, following the 2010 earthquake in Haiti. Based on its capsular lipopolysaccharide, Vibrio cholerae is classified into more than 200 serogroups, divided into O1, O139 and non-O1, non-O139. Non-O1 serogroups produce clinical features ranging from mild diarrhea to severe dehydration. In Cuba, circulation of non-O1, non-O139 V. cholerae has been reported both in outbreaks and sporadic cases. OBJECTIVE Describe the antimicrobial susceptibility of V. cholerae to the drugs of interest used in its treatment and verify the presence of enzymatic virulence factors. METHODS A descriptive, cross-sectional study was conducted in January through November 2014, based on 125 non-O1, non-O139 V. cholerae isolates obtained during 2013 and 2014 from patients with acute diarrheal disease (isolates from the National Reference Laboratory for Acute Diarrheal Diseases of the Pedro Kouri Tropical Medicine Institute, Havana). Bacteriological identification was performed according to conventional methods. Antimicrobial susceptibility was determined by the Bauer-Kirby agar diffusion method. The technique described by Robinson in 1986 was used to determine virulence factors, hemolytic activity and enzyme factors (DNase, elastase, gelatinase), and Karagozova’s method for the enzyme lecithinase. RESULTS Highest percentages of sensitivity were obtained for azithromycin (98.4%), doxycycline (97.6%) and ciprofloxacin (96.8%), and highest resistance values for ampicillin (60%), sulfonamide (46.4%) and trimethoprim–sulfamethoxazole (32%). Six resistance patterns were detected, four found in Cuba for the first time, as well as six patterns of multidrug resistance (4.8%). All isolates had at least two extracellular enzymes as virulence factors. The most frequent were gelatinase (90.4%) and lecithinase (77.6%). The percentage of virulence factors was lower in the group of isolates resistant to ≥2 antimicrobials. An inverse relationship was found between presence of enzymatic virulence factors and resistance in the isolates studied. CONCLUSIONS The results suggest that azithromycin, doxycycline and ciprofloxacin should continue to be used for treatment of V. cholerae-caused infections, and confirmed the presence of four new resistance patterns in isolates circulating in Cuba.