Carriage of micro-organisms by domestic cockroaches and implications on food safety

Domestic cockroaches Blattella germanica were trapped from various homes in Gaborone, Botswana using ‘Dyroach’ traps. Isolations of bacteria, yeasts and moulds were done on external body parts and on the faecal pellets using various selective media. Body parts of cockroaches were also fixed with OsO4 vapour for 24 h, sputter coated with gold under special conditions and examined in a Phillips (1) XL30 ESEM in low vacuum mode. A wide spectrum of bacteria including common food spoilage and pathogenic organisms, such as Bacillus spp., Staphylococcus spp., Escherichia coliPseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp. Salmonella sp., Shigella sp. and Serratia spp. were isolated. Yeasts commonly associated with food spoilage, such as Pichia sp., Candida sp. and Torulopsis spp. were found on many cockroaches. In addition, various groups of moulds, some associated with food spoilage and others known to produce mycotoxins, such as Aspergillus flavusAspergillus fumigatus and Aspergillus parasiticus were isolated. Antimicrobial sensitivities of bacterial isolates revealed resistance patterns to various agents. Since cockroaches are prevalent in homes, particularly in food preparation areas and since their body parts and faecal pellets have been found in food storage areas, concern about their impact on food quality and safety is raised and possible control measures including education of communities on proper sanitation are suggested. Des blattes domestiques Blattella germanica ont été piégées dans plusieurs maisons à Gaborone, au Botswana à l'aide de pièges ‘Dyroach’. On a réalisé des isolements de bactéries, de levures et de moisissures à partir de plusieurs morceaux d'exuvie et des fèces en utilisant différents milieux de culture sélectifs. Des morceaux d'exuvie ont également été fixés avec des vapeurs d'OsO4 pendant 24 h, recouverts d'une couche d'or et examinés en microscopie électronique à balayage sous vide à l'aide d'un microscope Phillips (1) XL30 ESEM. On a réussi à isoler un vaste spectre de bactéries comprenant des organismes pathogènes et présents dans les déchets de nourriture tels que Bacillus spp., Staphylococcus spp., Escherichia coliPseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp., Salmonella sp., Shigella sp. et Serratia spp. Des levures fréquemment associées aux déchets de nourriture, telles que Pichia sp., Candida sp. et Torulopsis spp. ont été trouvées sur plusieurs blattes. De plus, plusieurs groupes de mo