Surveillance of antimicrobial resistant bacteria in flies (Diptera) in Rio de Janeiro city

Ultrastructural changes in epithelial cells on different stages of sinantropic muscoid dipterans fed with spores of Brevibacillus laterosporus

Brevibacillus laterosporus is a sporulating bacteria, with typical canoe-shaped parasporal bodies attached to the spores. It has shown great biotechnological potential, including its broad pathogenic spectrum against different orders of insects and other invertebrates with medical-veterinary-sanitary importance. The high degree of synanthropy of muscoid dipterans and the damage they cause being a source of myiasis and carriers of pathogens encourage research into their population control. The objective of the study was to evaluate the histopathological effects caused by B. laterosporus NRS 590 on larvae and adults of M. domestica and C. megacephala. The flies were collected in garbage dumpsters, identified and the respective colonies were adapted to laboratory conditions (air-conditioned chamber with regulated humidity and temperature). Different concentrations of bacterial spore suspensions were offered to neo larvae and adults. Larvae and adults were dissected and intestinal epithelial cells of the flies, in temporal kinetics, were demonstrated using transmission electron microscopy (TEM) techniques. Irregular microvilli were observed in the intestines of both adult and larvae tested after 6 h of treatment. At 12 h and 24 h, intense cellular disorganization was observed and at 24 h and 48 h there was discontinuity of microvilli, cell extrusion and nuclear damage in some cells, as well. Spores of B. laterosporus NRS590 produce histopathological effects on both larvae and adults of synanthropic flies, being an alternative active principle in eco-friendly insecticides.

Bioactive Potential of Some Bacillus thuringiensis Strains from Macapá, Amazon, Brazil, Against the Housefly Musca domestica (Diptera: Muscidae) Under Laboratory Conditions

The high pathogenic activity of Bacillus thuringiensis (Bt) strains against various insect orders has positioned it as the most effective, environmentally safe, and sustainable approach to integrated insect management. We aimed to identify Bt strains capable of effectively controlling the housefly Musca domestica, a species of significant medical, veterinary, and public health concern. Twelve Bt strains from Macapá, Brazil, were tested against housefly larvae. PCR was employed to detect genes encoding Cry and Cyt proteins and Vips. Six strains exhibited 70 to 100% larval mortality, with five containing cry genes, none harboring cyt genes, and four carrying vip genes. Scanning electron microscopy revealed the production of crystal inclusions with distinct morphologies: spherical (TR4J, SOL5DM, SOL6RN), cuboidal and bipyramidal (TRO1TN and TRO2MQ), and spherical and bipyramidal (UNI2MA). The potential presence of genes from the cry1, cry2, vip1, and vip3 families suggests that these strains also exhibit bioinsecticidal activity against other muscoid flies and insect pests across various orders. This study underscores the bioactive potential of these Brazilian Bt strains for developing new bioinsecticides.

Hospital Wastes as Potential Sources for Multi-Drug-Resistant ESBL-Producing Bacteria at a Tertiary Hospital in Ethiopia

The hospital environment is increasingly becoming an important reservoir for multi-drug-resistant (MDR) Gram-negative bacteria, posing serious challenges to efforts to combat antimicrobial resistance (AMR). This study aimed to investigate the role of hospital waste as a potential source of MDR ESBL-producing bacteria. Samples were collected from multiple sources within a hospital and its vicinity, including surface swabs, houseflies, and sewage samples. The samples were subsequently processed in a microbiology laboratory to identify potential pathogenic bacteria and confirmed using MALDI-TOF MS. Bacteria were isolated from 87% of samples, with the predominant isolates being E. coli (30.5%), Klebsiella spp. (12.4%), Providencia spp. (12.4%), and Proteus spp. (11.9%). According to the double disc synergy test (DDST) analysis, nearly half (49.2%) of the bacteria were identified as ESBL producers. However, despite exhibiting complete resistance to beta-lactam antibiotics, 11.8% of them did not test positive for ESBL production. The characterization of E. coli revealed that 30.6% and 5.6% of them carried blaCTX-M group 1 type-15 and blaNDM genes, respectively. This finding emphasizes the importance of proper hospital sanitation and waste management practices to mitigate the spread of AMR within the healthcare setting and safeguard the health of both patients and the wider community.

First Identification of bla NDM-1 Producing Escherichia coli ST 9499 Isolated from Musca domestica in the Urban Center of Rio de Janeiro, Brazil

The present study presents phenotypic and molecular characterization of a multidrug-resistant strain of Escherichia coli (Lemef26), belonging to sequence type ST9499 carrying a blaNDM-1 carbapenem resistance gene. The bacterium was isolated from a specimen of Musca domestica, collected in proximity to a hospital in Rio de Janeiro City, Brazil. The strain was identified as E. coli by matrix-assisted laser desorption-ionization time of flight mass spectrometry (Maldi-TOF-MS) and via genotypic analysis (Whole-Genome Sequencing-WGS), followed by phylogenetic analysis, antibiotic resistance profiling (using phenotypic and genotypic methods) and virulence genotyping. Interestingly, the blaNDM-1 was the only resistance determinant detected using a panel of common resistance genes, as evaluated by PCR. In contrast, WGS detected genes conferring resistance to aminoglycosides, fluoroquinolones, quinolones, trimethoprim, beta-lactams, chloramphenicol, macrolides, sulfonamide, tetracycline, lincosamide and streptogramin B. Conjugation experiments demonstrated the transfer of carbapenem resistance, via acquisition of the blaNDM-1 sequence, to a sensitive receptor strain of E. coli, indicating that blaNDM-1 is located on a conjugative plasmid (most likely of the IncA/C incompatibility group, in association with the transposon Tn3000). Phylogenetic analyses placed Lemef26 within a clade of strains exhibiting allelic and environment diversity, with the greatest level of relatedness recorded with a strain isolated from a human source suggesting a possible anthropogenic origin. Analysis of the virulome revealed the presence of fimbrial and pilus genes, including a CFA/I fimbriae (cfaABCDE), common pilus (ecpABCDER), laminin-bind fimbrae (elfADG), hemorrhagic pilus (hcpABC) and fimbrial adherence determinants (stjC) indicates the ability of strain Lemef26 to colonize animal hosts. To the best of our knowledge, this study represents the first report of blaNDM-1 carbapenemase gene in an E. coli strain isolated from M. domestica. In concordance with the findings of previous studies on the carriage of MDR bacteria by flies, the data presented herein provide support to the idea that flies may represent a convenient means (as sentinel animals) for the monitoring of environmental contamination with multidrug-resistant bacteria.

Flies as Vectors and Potential Sentinels for Bacterial Pathogens and Antimicrobial Resistance: A Review

The unique biology of flies and their omnipresence in the environment of people and animals makes them ideal candidates to be important vectors of antimicrobial resistance genes. Consequently, there has been increasing research on the bacteria and antimicrobial resistance genes that are carried by flies and their role in the spread of resistance. In this review, we describe the current knowledge on the transmission of bacterial pathogens and antimicrobial resistance genes by flies, and the roles flies might play in the maintenance, transmission, and surveillance of antimicrobial resistance.

Ultrastructural and pathogenicity of Brevibacillus laterosporus against sinantropic muscoid dipterans

Brevibacillus laterosporus has entomopathogenic potential against several orders of insects and its wide bioactivity is associated with a variety of strain-specific molecules. In order to avoid the use of synthetic insecticides, along with the need to control insect pests, microbial control has been widely used. Muscoid dipterans are known for their medical-veterinary and sanitary importance, and synanthropy. The enormous biotechnological potential of B. laterosporus has been demonstrated, but there are still few studies with muscoid dipterans. The aim of the study was to verify the mortality of B. laterosporus NRS590 on synanthropic flies and to characterize its different cell stages ultrastructurally. The flies were collected from garbage bins and the colonies were adapted to the laboratory conditions. Bioassays with neo larvae were carried out from the bacterial growth in the phases: vegetative (6 hr), sporangium (20 hr), and free spores (44 hr). An aliquot of each phase was collected for Transmission (TEM) and Scanning Electron Microscopy (SEM). The effectiveness of NRS590 was observed in the sporulation phase, where the corrected mortality was 83.3, 85.1, and 99% for Chrysomya megacephala, Chrysomya putoria, and Musca domestica, respectively. The parasporal body was observed in detail on the entire spore surface. Although our knowledge of this bacterium is growing, it remains to be determined the real virulence factors responsible for the wide entomopathogenic activity observed on muscoid dipterans. Therefore, this study can provide subsidies for the improvement of efficient and safe microbial control techniques for the environment and living beings.