Salmonella Contamination during Production of Cantaloupe: A Binational Study

Abstract

Six cantaloupe farms and packing plants in South Texas (950 cantaloupe, 140 water, and 45 environmental samples), including the Rio Grande Valley area, and three farms in Colima State, Mexico (300 cantaloupe, 45 water, and 15 environmental samples), were sampled to evaluate cantaloupe contamination with Salmonella and Escherichia coli during production and processing. Samples collected from external surfaces of cantaloupes, water, and the environments of packing sheds on cantaloupe farms were examined for the presence of Salmonella and E. coli. Of a total of 1,735 samples collected, 31 (1.8%) tested positive for Salmonella. Fifteen Salmonella serotypes were isolated from samples collected in Texas, and nine from samples collected in Colima. Two serotypes (Poona and Oranienburg) that have been associated with three large Salmonella outbreaks in the United States and Canada linked to the consumption of contaminated cantaloupe were found in water samples collected at four farms (three from the United States). Susceptibility of Salmonella isolates to 10 antimicrobials was evaluated by disk diffusion. Eighty-eight percent of the isolates from the United States and Mexico were pansusceptible to the antimicrobials tested; eight isolates from the United States demonstrated an intermediate susceptibility to streptomycin and only two isolates were resistant to the same antimicrobial. From Mexico, four isolates showed an intermediate susceptibility to streptomycin and one isolate was resistant to nalidixic acid and streptomycin. Repetitive sequence-based PCR analysis of Salmonella isolates helped to trace potential sources of Salmonella contamination in source water and in subsequent water samples obtained after the filtration systems of U.S. and Mexican cantaloupe farms. No differences could be seen between the levels of Salmonella contamination in melons from both countries.

Prevalence and serovar diversity of Salmonella spp. in primary horticultural fruit production environments

“…The overall prevalence rate (5.3%) observed in the present study is higher than what has been generally reported from previous studies in the developed world (Duffy et al, 2005;Castillo et al, 2004;Giusti et al, 2010;Gorski et al, 2011;Johnston et al, 2005;Micallef et al, 2012., Mukherjee et al, 2006, but comparatively lower than that reported in some other developing countries (Abakpa et al, 2015;Ndiaye et al, 2011;Uyttendaele et al, 2014). …”

Investigation of a food-borne Salmonella Oranienburg outbreak in a Mexican prison

“…Its causes include the consumption of black pepper [32], cheese [33], fruit salad (including cantaloupe and honeydew melons) [34], semi-dry cuttlefish [35], and chocolate [36]. In Mexico, this serotype has been isolated from farm [37] and zoo [38] animal feces, from meat for human consumption [28], and from fields where cantaloupe melon was grown [39].…”

Scientific Opinion on the risk posed by pathogens in food of non-animal origin. Part 1 (outbreak data analysis and risk ranking of food/pathogen combinations)

“…Melon ground spots have been demonstrated to have significantly greater microbial populations than non ground spot areas of melon rinds (Parnell et al, 2005) potential for melon-to-melon, food-contact surface-to-melon, and melon-to-water-to-melon cross contamination (Castillo et al, 2004;FDA, 2009b); (4) Melons are commonly cooled by forced-air cooling or by use of a chilled water drench or flume immersion. The water use during cooling may be a significant source of microbial cross-contamination if of poor quality (FDA, 2009b).…”