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Background: Insect-associated actinomycetes represent a potentially rich source for discovering bioactive metabolites. However, the diversity, antibacterial and phytotoxic activities of symbiotic actinomycetes associated with Periplaneta fuliginosa have not yet been conducted., Results: A total of 86 strains of actinomycetes were isolated from the cornicles and intestines of both nymphs and adults of P. fuliginosa . Diversity analysis revealed that the isolated strains were preliminarily identified as 17 species from two genera, and the dominant genus was Streptomyces . A total of 36 crude extracts (60%) obtained from the supernatant of the 60 fermented strains exhibited a potent antibacterial activity against at least one tested pathogenic bacterium. Among these active strains, 27 crude extracts (75%) exhibited phytotoxic activity against the radicle of Echinochloa crusgalli . Furthermore, seven known compounds, including methoxynicotine ( 1 ), (3Z,6Z)-3-(4-methoxybenzylidene)-6-(2-methylpropyl) piperazine-2,5-dione ( 2 ), XR334 ( 3 ), 1-hydroxy-4-methoxy-2-naphthoic acid ( 4 ), nocapyrone A ( 5 ), β-daucosterol ( 6 ), and β-sitosterol ( 7 ) were isolated from an active rare actinomycete Nocardiopsis sp. ZLC-87 which was isolated from the gut of adult P. fuliginosa . Among them, compound 4 exhibited moderate antibacterial activity against Micrococcus tetragenus , Staphylococcus aureus , Escherichia coli , and Pseudomonas syringae pv. actinidiae with the zone of inhibition (ZOI) of 14.5, 12.0, 12.5, and 13.0 mm at a concentration of 30 μg/disc, respectively, which was weaker than those of gentamicin sulfate (ZOI of 29.5, 19.0, 18.5, and 24.5 mm). In addition, the compound 4 had potent phytotoxic activity against the radicle of E. crusgalli and Abutilon theophrasti with the inhibition rate of 65.25% and 92.68% at the concentration of 100 μg/mL., Conclusion: Based on these findings, this study showed that P. fuliginosa -associated actinomycetes held promise for the development of new antibiotic and herbicide resources., Competing Interests: The authors declare that they have no competing interests., (© 2024 Liu et al.)

Background: Flies and cockroaches are two insects in close contact with human beings. They are carriers of human pathogenic bacteria on the external areas of their bodies or in their digestive tracts. This study examines Periplaneta americana and Musca domestica collected from the residential areas of six districts in Tangier, Morocco., Methodology: In total, 251 bacteria were isolated from external areas of the participants' bodies and the antimicrobial susceptibility was calculated., Results: The predominant bacterial species included Escherichia coli (17.9%), Klebsiella spp. (14.7%), Providencia spp. (9.6%), Staphylococcus spp. (15.1%) and Enterococcus spp. (11.6%). The study showed no difference between the species of bacterial strains from American cockroaches and houseflies. Carbapenems and aminoglycosides were active against 100% of the Gram-negative bacilli isolated in this study. Staphylococcus spp. strains were susceptible to linezolid, vancomycin, daptomycin, levofloxacin and cotrimoxazole, and no antibiotic resistance was found in Enterococcus spp., Conclusions: In our setting, although both cockroaches and flies collected from residential areas may be vectors of human pathogenic bacteria, the infections caused by them are easily treatable as a result of the high susceptibility of their bacteria to antibiotics routinely used in the community or in hospitals.

Cockroaches carry microorganisms to sterilized materials, equipment and non-contaminated food in hospitals and in homes. Hence, they are regarded as major microbial vectors. We isolated and identified microorganisms from living cockroaches captured from a Brazilian health care institution and we determined the antimicrobial susceptibility profile of the isolates. Following collection, cockroaches were immobilized at 4 degrees C for 10 to 20 minutes, immersed in 0.8% saline solution and then homogenized. Next, the suspension was seeded in culture media: brain and heart agar infusion, MacConkey agar, Naito agar, and they were incubated for up to 48 hours at 37 degrees C. Sabouraud agar cultures were incubated at ambient temperature. The microbial colonies were analyzed with a stereomicroscope to count and phenotypically identify the colony-forming units (cfu). The disc-diffusion method was used to determine the profile of susceptibility to antimicrobials. Among the 103 cockroaches analyzed, fungi were found in 97%, enterobacteria in 74.6% and coagulase-negative staphylococci (CNS) in 25.40%. Among the enterobacteria, 96% were resistant to gentamicin, 84% to ampicillin, 75.3% to caphalothin, 66.7% to ampicillin-sulbactam, 50% to aztreonam and 30% to chloramphenicol. Among the CNS, 61% were resistant to oxacillin. We concluded that cockroaches carry organisms associated with nosocomial infections and that are resistant to antimicrobials. This fact contributes to the epidemiological chain, complicating therapeutics, and consequently, medical costs are increased.

A total of 221 cockroaches (Blatta and Periplaneta spp.), collected in hospitals, houses, animal sheds, grocery stores and restaurants, in various parts of South Kanara District, a south-west coastal region of India, were studied bacteriologically for the presence of various salmonellas. Salmonellas were isolated from 4.1% of these cockroaches. Nine strains of salmonellas were recovered, belonging to five serotypes--Salmonella bovismorbificans, S. oslo, S. typhimurium, S. mbandaka and S. braenderup, the former two being the commonest serotypes. All salmonellas were resistant to one or other of 11 antibacterial drugs used in the susceptibility test. Isolation of salmonellas from cockroaches collected from the livestock premises and human dwellings suggested that they may act as significant reservoirs of salmonella in nature. Recovery of serotypes, phage types and R-types that were commonly isolated from humans and animals of this locality, suggested a transmission role for cockroaches. By harbouring potentially pathogenic, drug-resistant salmonellas, these wandering arthropods may pose dangerous infective hazards to humans and animals.