Bacterial, fungal and parasitic contamination of cockroaches in public hospitals of Hamadan, Iran.

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.

Meta-analysis of case-referent studies of specific environmental or occupational pollutants on lung cancer.

BACKGROUND: Meta-analysis is a statistical tool for combining and integrating the results of independent studies of a given scientific issue. The present investigation was initiated to investigate case-referent studies of lung cancer risk from specific environmental and occupational pollutants, using detailed individual exposure data. MATERIALS AND METHODS: To examine the risk of lung cancer associated with environmental and occupational pollutants, a meta-analysis of published case-control studies was undertaken using a random effects model. For this study, the papers were selected for review from electronic search of PubMed, Medline and Google Scholar during 1990-2006. The principal outcome measure was the odds ratio for the risk of lung cancer. Twelve study reports detailing the relationship between the lung cancer and the type of exposure were identified. RESULTS: The odds ratio of asbestos, cooking fuel, cooking fumes, motor and diesel exhaust related to lung cancer were 1.67, 1.99, 2.52 and 1.42 (P < 0.001), respectively. The odds ratio of metal fumes related to lung cancer was 1.28 (0.001 P < 0.01). The combined odds ratio for the environmental and occupational exposure related to lung cancer was 1.67 (P < 0.001). CONCLUSIONS: The meta-analysis of the present study shows the magnitude association between asbestos, cooking fumes, cooking fuels, motor and diesel exhaust, with lung cancer risk. Lung cancer risk may be reduced by controlling exposure levels.