Cockroaches are popularly known for being vectors to several dozens of infectious bacteria. Several researchers had focused on studying these bacterial communities, recently B.T Thomas of the Department of Microbiology, Olabisi Onabanjo University, Nigeria carried out a comparative study of cultural and molecular techniques for the identification of bacterial contaminants of cockroaches.
He believes that the increasing trends of insect associated bacterial infection in humans were severely hampered by the disparaging number of bacteria obtained with the culture-based technique. He therefore performed a study to ascertain how the analysis of the 16S rDNA sequences would compare in terms of precision and reliability to the most adoptable culture-based technique.
Results from his study showed enhanced accuracy of molecular technique over the cultural method as only 249 (69%) of the total isolates were correctly identified by the cultural method to represent a total of 114 (31%) discrepant species while 100% correct identification was observed with the molecular technique. The most predominant of these bacterial isolates from both the external surfaces and the gut environment was Escherichia coli 43 (20.8%) and 24 (15.5%) respectively. The Gram positive organisms isolated were Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis, and Enterococcus faecalis with a prevalence rate of 8 (3.8%), 14 (6.7%), 8 (3.8%) and 9 (4.3%) from external surfaces and 2 (1.3%), 6 (3.9%), 2 (1.3%) and 7 (4.5%) from gut environment respectively. The least isolated organisms in the external surfaces were Serratia marscencens and Citrobacter werkmanii with a distribution rate of 3(1.4%) while Citrobacter freundii 2(1.3%) was the least isolated organism from cockroach gut environment.
His research therefore showed that the molecular analysis of the 16S rDNA sequences is more efficient than culture-based technique for the identification of bacterial contaminants of cockroaches because occurrences of misidentification are very much abated by this method. The research thus encouraged researchers to use molecular analysis of the 16S rDNA sequences for future identification purpose.