RESUMEN
BACKGROUND & OBJECTIVES: To determine the possible role of cockroaches in dissemination of medically important microorganisms, a study was carried out in public hospitals and residential areas of Hamadan city, west of Iran. Bacteria, fungi and parasites of medical importance were isolated and identified. The total number of Blattella germanica collected from hospitals were 133 as the case group. The cockroaches collected from residential areas were 45 as the control group. METHODS: A total of 178 cockroaches were collected, over a period of two years (133 from hospitals; and 45 from residential areas) in Hamadan. Medically important microorganisms were isolated from external and internal surfaces using standard methods. RESULTS: In the case group, 130 out of 133 (98%) Blattella germanica showed contamination with high bacterial load (more than 1 x 10(3)) whereas only 2 out of 45 (4.45%) cockroaches of the control group were carrying medically important bacteria with high bacterial load. Bacteriological examinations revealed that almost all test cockroaches had at least one of the following microorganisms either in their body surface or digestive tract. Enterobacter (22.6%), Klebsiela (21%), Enterococcus (17.3%), Staphylococcus (16.5%), Esherichia coli and Streptococcus (8.3%), Pseudomonas (3%), and also Shigella, Haemophilus and group A beta-hemolytic Streptococcus each less than 1%. In addition the results showed (74.4.%) of test cockroaches harboured fungi-Candida (48.9%), Mucor (10.5%), Aspergillus niger (7.5%), Rhizopus (4.5) and also Penicillium and Aspergillus fumigans each 1.5%. Some parasitic worms of medical importance were also isolated from the test cockroaches, but carriage rates were low. INTERPRETATION & CONCLUSION: The data from this study emphasise the importance of cockroaches as potential vectors of medically important microorganisms such as pathogenic bacteria and fungi in hospital environments.