COPAIA 7. Resistencia Antimicrobiana y seguridad alimentaria

La OMS ha identificado al aumento de la resistencia antimicrobiana como una crisis sanitaria a nivel global. Está siendo propagado por la mala utilización de medicamentos antimicrobianos, programas para la prevención y control de infecciones que son inadecuadas o inexistentes, medicamentos de mala calidad, capacidad laboratorial escasa, vigilancia inadecuada, regulación insuficiente del uso de medicamentos antimicrobianos. Un enfoque robusto y colaborativo será necesario para combatir la resistencia antimicrobiana, involucrando a países en todas las regiones y a actores de varios sectores.

The WHO has identified the rise of antimicrobial resistance as a global health crisis. It is being propagated by misuse of antimicrobial medicines, inadequate or inexistent programmes for infection prevention and control, poor-quality medicines, weak laboratory capacity, inadequate surveillance, insufficient regulation of the use of antimicrobial medicines. A strong, collaborative approach will be required to combat antimicrobial resistance, involving countries in all regions and actors in many sectors.

Antimicrobial-resistant Campylobacter in the food chain in Mexico.

We describe prevalence and antimicrobial susceptibility results for thermophilic Campylobacter isolates collected from humans, food, and food-animals in an integrated food chain surveillance network in Mexico. From 2003 to 2006, stool samples were collected from children with diarrhea at state sentinel hospitals. Concurrently, fecal samples from asymptomatic children in kindergartens, as well as raw chicken, pork and beef from retail outlets, and food-animal intestines from slaughterhouses were all collected in 65 cities from four different states. C. jejuni was identified with a standardized hippurate test. Hippurate negative, indoxyl acetate positive isolates were classified as Campylobacter spp. Susceptibility testing was performed by agar dilution according to Clinical and Laboratory Standards Institute guidelines. A total of 1,259 C. jejuni and 1,797 Campylobacter spp. isolates were recovered from 11,811 samples. Chicken was significantly more contaminated for both intestinal samples (93.6%) and meat products (58.3%), compared with swine (71.4%)/pork (14.6%) samples, and cattle (25.1%)/beef (5.3%) samples (p<0.001). Campylobacter was recovered from 5.1% of children with diarrhea and from 3.2% of asymptomatic children. Chicken was significantly more likely to harbor ciprofloxacin-resistant C. jejuni (85.8%) than swine (62.5%, OR=3.6), cattle (39.8%, OR=9.3), or humans (58.2%, OR=4.4). No significant differences were found for ciprofloxacin-resistant Campylobacter spp. among food-animals, but the rate in food-animals was significantly higher than in humans (84% vs. 56.7%, OR=4.0). Swine was significantly more likely to harbor erythromycin-resistant C. jejuni (14.8%) than chicken (3.5%, OR=4.9), cattle (1.8%, OR=9.3), or humans (3.0%, OR=5.7), and was associated with higher rates of erythromycin-resistant Campylobacter spp. (41.9%) than chicken (10.5%, OR=6.1) and humans (11.9%, OR=5.3). The high resistance rates to ciprofloxacin preclude the use of fluoroquinolones for treatment of campylobacteriosis in Mexico. Our results emphasize the need for ongoing and integrated surveillance of antimicrobial usage and antimicrobial susceptibility in humans and animals.

Integrated food chain surveillance system for Salmonella spp. in Mexico.

Few developing countries have foodborne pathogen surveillance systems, and none of these integrates data from humans, food, and animals. We describe the implementation of a 4-state, integrated food chain surveillance system (IFCS) for Salmonella spp. in Mexico. Significant findings were 1) high rates of meat contamination (21.3%-36.4%), 2) high rates of ceftriaxone-resistant S. Typhimurium in chicken, ill humans, and swine (77.3%, 66.3%, and 40.4% of S. Typhimurium T isolates, respectively), and 3) the emergence of ciprofloxacin resistance in S. Heidelberg (10.4%) and S. Typhimurium (1.7%) from swine. A strong association between Salmonella spp. contamination in beef and asymptomatic Salmonella spp. infection was only observed in the state with the lowest poverty level (Pearson r = 0.91, p<0.001). Pulsed-field gel electrophoresis analysis of 311 S. Typhimurium isolates showed 14 clusters with 102 human, retail meat, and food-animal isolates with indistinguishable patterns. An IFCS is technically and economically feasible in developing countries and can effectively identify major public health priorities.

Rapid and widespread dissemination of multidrug-resistant blaCMY-2 Salmonella Typhimurium in Mexico.

OBJECTIVES: We describe the emergence and dissemination of multidrug-resistant (MDR) Salmonella Typhimurium in humans, retail meat and food animals from Yucatan, Mexico. METHODS: Salmonella Typhimurium isolates were collected through an active surveillance system and tested for susceptibility to 12 antimicrobial agents. Isolates that were non-susceptible to ceftriaxone were tested with 10 additional antimicrobials and assayed by PCR for the presence of CMY, CTX-M, SHV, TEM and OXA beta-lactamase genes. Plasmid-borne phenotypes were identified by transfer to susceptible Escherichia coli. Isolates from humans, retail meat and food animals were compared by PFGE to determine genetic relatedness. RESULTS: MDR Salmonella Typhimurium containing a plasmid-mediated blaCMY-2 AmpC beta-lactamase rose from 0% (0/27) during 2000 and 2001 to 75% (63/84) in 2004 and 2005 (P<0.0001). MDR blaCMY-2 Salmonella Typhimurium (n=115) was most common in ill children (44.3%) and pork or swine intestine (36.5%). In several cities, MDR blaCMY-2 Salmonella Typhimurium from retail meat or swine intestine exhibited PFGE patterns and antibiograms indistinguishable from those in strains recovered from hospitalized children. The CMY gene was transferred to E. coli by electroporation, along with resistance to three to six other antimicrobials. Children with MDR blaCMY-2 Salmonella Typhimurium infection (n=39) had a higher frequency of systemic infection (13% versus 0%), mortality (8% versus 0%) and hospital re-admission due to protracted diarrhoea (28% versus 17%) than children with non-MDR-Salmonella Typhimurium (n=24), although the difference was not statistically significant. CONCLUSIONS: The rapid and widespread dissemination of MDR blaCMY-2 Salmonella Typhimurium in Mexico calls for urgent interventions to contain this potentially fatal pathogen.

Nontyphoidal Salmonella from human clinical cases, asymptomatic children, and raw retail meats in Yucatan, Mexico.

BACKGROUND: We report the results of a 3-year Salmonella surveillance study of persons with diarrhea; asymptomatic children; and retail pork, poultry, and beef in Yucatan, Mexico. METHODS: Isolates were characterized according to serotype, antimicrobial susceptibility, and genetic relatedness with pulsed-field gel electrophoresis. RESULTS: Salmonella Typhimurium was the most common serotype found in ill humans (21.8% of isolates), followed by Salmonella Agona (21% of isolates). Salmonella Enteritidis was a minor serotype (4.2% of isolates). Asymptomatic children carried S. Agona (12.1% of isolates), Salmonella Meleagridis (11.6% of isolates), Salmonella Anatum (8% of isolates) and S. Enteritidis (5.8% of isolates). A high percentage of retail meat samples contained Salmonella; it was most commonly found in pork (58.1% of samples), followed by beef (54% of samples) and poultry (39.7% of samples). Resistance to oral drugs used for the treatment of salmonellosis was observed for ampicillin (14.6% of isolates were resistant), chloramphenicol (14.0% of isolates), and trimethoprim-sulfamethoxazole (19.7% of isolates). Resistance to ceftriaxone emerged in 2002 and was limited to the serotype S. Typhimurium. Twenty-seven percent of the isolates were resistant to nalidixic acid, and none were resistant to ciprofloxacin. Multidrug resistance was most common among isolates of serotypes S. Typhimurium and S. Anatum. Pulsed-field gel electrophoresis showed that strains found in retail meats were genetically identical to strains found in both asymptomatic children and ill patients. CONCLUSIONS: Our study found a high prevalence of Salmonella in retail meats and persons with enteric infection; many of these isolates were resistant to clinically important antimicrobials. A random selection of isolates from people and retail meat showed genetic relatedness, which suggests that, in Yucatan, considerable transfer of Salmonella occurs through the food chain.