Isolation and Identification of Some Pathogenic Bacteria from the External Surfaces and Digestive Tract of the American Cockroach (Periplaneta americana)

Abstract

The American cockroach (Periplaneta americana) A common pest in city environments, its potential role in the transmission of pathogenic microorganisms is known. This research aims to isolate and identify bacterial species found on exoskeleton and inside the gastrointestinal tract of this insect. The samples were collected from residential buildings using sterile trapping methods. The exterior surfaces and gut were emptied under sterile conditions to obtain bacterial samples. The samples were cultured on general and selective food media, then subjected to microscopic examination after gram dye, and biochemical tests to determine Bacterial species. Blood agar, central MacConkey agar, Mannitol salt agar medium, Salmonella-Shigella agar medium, Eosin Methylene Blue agar, and Nutrient agar medium the results showed the presence of several types of bacteria, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. These findings point to the potential role this insect may play in mechanically transporting bacteria in human environments. Background: Periplaneta americana, commonly known as the American cockroach, is increasingly recognized as a vector for pathogenic and antibiotic-resistant bacteria in both residential and healthcare settings. This study aimed to isolate, identify, and analyze the bacterial load present on the external surfaces and in the digestive tracts of these cockroaches. Methods: A total of 25 P. americana specimens were collected from human dwellings in urban areas. Bacterial isolation was performed from both the external surface and gut content using standard microbiological techniques. Gram staining, biochemical testing, and Vitek2 system analysis were employed for identification and characterization of bacterial isolates. Results: A total of 200 bacterial isolates were obtained—100 from external surfaces and 100 from gut contents. Among these, 80% were Gram-negative and 20% Gram-positive. The predominant species were Escherichia coli (45%), Klebsiella pneumoniae (30%), Staphylococcus aureus (15%), and Pseudomonas aeruginosa (10%). The presence of multidrug-resistant organisms, including ESBL-producing and metallo-beta-lactamase-producing strains, highlights the potential of cockroaches to act as reservoirs and transmitters of antimicrobial resistance genes.