Journal of School of Public Health and

Hospitals are habitually thought of as places where people "recover from disease". But failure to control agents of disease in these institutions can create or worsen disease and infection such nosocomial infections constitute a major threat to all hospitalized patients. The German cockroach (Blattella germanica) can be an effective transmitter of nosocomial infections by virtue of its ubiquitous presence and its behavioral characteristics. This research is focused on nosocomial organisms in Imam Khomeini and Shariati hospitals (belonging to Tehran University of Medical Sciences) and may be a first step in devising effective infection control strategies.
After recording data on the collection site, the collected cockroaches were transferred to a laboratory, where bacteria and fungi were isolated from the body surface and the digestive tube. The specimens were also subjected to insecticide sensitivity tests by the mortality and knock-down test methods.
Cultures of the external body surface yielded a total of 77 fungal colonies (filamentous fungi, Actinomycetes, yeasts and yeast-like organisms), while those of the digestive tract produced 83 colonies. Notable among these isolates were the highly virulent Aspergillus fumigatus and Aspergillus flavus species.
Bacterial studies showed that 100% of the roaches carried rich bacterial floras, most commonly including Klebsiella, Pseudomonas, Proteus, Citrobacter, Enterobacter and Serratia species. Many of these bacteria demonstrated antibiotic resistance, suggesting that the contaminants belonged to the hospital milieu. These results establish cockroaches as effective mechanical transmitters of multi-drug resistant bacteria.
Mortality tests revealed a high degree of resistance to permethrin, tolerance to Aicon, and sensitivity to other insecticides. Knock-down tests showed high permethrin resistance, tolerance to Aicon and deltamethrin, and sensitivity to Sulfac.