Background: Gallibacterium anatis is incriminated frequently in severe economic losses and mortalities in the poultry industry. This study aimed to detect the prevalence of G. anatis in layer chickens, sequence analysis, the antibiogram profiles, and PCR screening of virulence determinants and antibiotic resistance genes. Methods: Accordingly, 300 samples (tracheal swabs, ovary and oviduct, and lung) were randomly collected from 100 diseased layer chickens from private commercial layer farms at Elsharkia Governorate, Egypt. The bacteriological examination was carried out. The retrieved isolates were tested for 16S rRNA-23S rRNA gene sequencing, antibiogram profiling, PCR screening of virulence (gtxA, fifA, and gyrB), and antibiotic resistance genes (bla_ROB, aphA1, tetB, and tetH). Results: The prevalence of G. anatis was 25% in the examined diseased layer chickens. The sequence analyses emphasized that the tested strains derived from a common ancestor and exhibited a notable genetic similarity with other G. anatis strains from USA, China, and Denmark. The isolated G. anatis strains were highly resistant to sulfamethoxazole-trimethoprim, oxytetracycline, penicillin, ampicillin, kanamycin, neomycin, and erythromycin. The PCR revealed that the retrieved G. anatis strains carried gtxA, gyrB, and fifA virulence genes with a prevalence of 100%, 100%, and 38.3%, respectively. Approximately 30.1% of the retrieved G. anatis isolates were XDR to six antimicrobial classes and harbored bla_ROB, aphA1, and tetB resistance genes. Moreover, 20.5% of the isolated G. anatis strains were MDR to three different classes and carried bla_ROB and tetH resistance genes. Conclusion: Briefly, this study emphasized the existence of XDR and MDR G. anatis strains in poultry. Florfenicol and norfloxacin displayed a promising antimicrobial effect against the emerging XDR and MDR G. anatis in poultry. The emergence of XDR and MDR G. anatis is considered a public health alarm. Graphical Abstract:

Shiga-toxigenic Escherichiacoli (STEC) is incriminated in severe hemorrhagic enteritis in dogs, which is considered a veterinary and public health alarm. To investigate the prevalence, antimicrobial resistance patterns, virulence determinants, and distribution of antimicrobial resistance genes in STEC strains isolated from dogs: 80 fecal samples were obtained from diseased dogs suffering from hemorrhagic diarrhea from pet animal clinics in Ismailia governorate, Egypt. The obtained samples were examined bacteriologically. Moreover, the retrieved isolates were tested for serogrouping, Congo-red binding, antimicrobial resistance, and PCR-based determination of virulence and antimicrobial resistance genes. The prevalence of E.coli in the examined diseased dogs was 23.75% (19/80). The serogrouping of the recovered isolates revealed that 84.2% of the tested isolates were distributed into three serogroups: O146 (36.8%), O111 (31.5%), and O26 (15.7%). Meanwhile, three isolates were untypable (15.8%). Moreover, all the tested E.coli serovars were positive for CR-binding. PCR revealed that the prevalence of stx1, eaeA, hlyA, and stx2 virulence genes was 100%, 100%, 100%, and 47.3%, respectively. Our findings revealed that 31.5% of the recovered isolates showed MDR to five antimicrobial classes and harbored bla_TEM, bla_CTX-M, tetA, tetB, and sul1 genes. Alarmingly, three isolates were carbapenem-resistant. Two strains harbored the bla_KPC gene, while one strain carried the bla_NDM-1 gene. Concisely, as far as we know, this is the first study that reported the existence of MDR-STEC in dogs in Egypt. The stx1 gene is the most predominant Shiga toxin gene that accompanied the STEC isolated from hemorrhagic enteritis in dogs. The emerging MDR-STEC in dogs commonly harbors bla_TEM, bla_CTX-M, sul1, tetA, tetB, and qnrA resistance genes. Meropenem, levofloxacin, and tigecycline exhibited talented antimicrobial activity against MDR-STEC isolated from dogs.

Pseudomonas aeruginosa is an opportunistic pathogen of public health concern. This study aimed to investigate the prevalence of P. aeruginosa, some virulence factors, and antimicrobial resistance patterns and highlight the potential pathways of horizontal bla_SHV-resistant gene transfer from diverse sources. A total of 220 samples were collected from fish (n = 90), water (n = 30), poultry (n = 50), and humans (n = 50). All samples were isolated, confirmed by the Vitek 2 system, and tested against antimicrobial agents. Some virulence and resistance genes were examined by PCR and sequenced for the bla_SHV-resistant gene from four selected isolates from each source. SPSS v26, with chi-squared tests and Pearson correlations (p < 0.05), was implemented for statistical investigation. P. aeruginosa was isolated at 33.3%, 20%, 14%, and 24% from fish, water, poultry, and humans, respectively. Using the diffusion disk method, extensively drug-resistant (XDR) and multidrug-resistant (MDR) strains were detected. All strains harbored the oprL and toxA genes, while the lasB gene was present in 40% of fish samples but not present in human samples. All strains lacked the exoS gene. The tetA, sul1, bla_SHV, and bla_TEM resistance genes were detected at different percentages. The bla_SHV genes from fish and water isolates were closely related to each other and showed similarity to those of the human isolates. The poultry isolates formed a separate phylogenetic lineage. The emergence of XDR and MDR P. aeruginosa highlights a possible public health threat. Based on the gene similarity between fish and water isolates, our results suggest that these isolates have a common origin. The similarity between the human isolates and environmental isolates (fish and water) raises concerns about possible transmission to humans.

Escherichia coli (E. coli) is a zoonotic bacterial pathogen commonly found in human, birds and animals. The widespread use of broad-spectrum beta-lactams for poultry treatment, has resulted in the production of extended spectrum β-lactamases (ESBLs) in E. coli. In this study, we analyzed the antimicrobial resistance pattern of E. coli isolates from broiler chickens and ducks with clinical colibacillosis, and investigated the presence of beta-lactam (blaTEM, blaSHV, ampC, and blaCTX-M) and fluoroquinolone (qnrS and qepA) resistance genes using PCR. E. coli isolates showed a higher resistance against beta-lactams: penicillin G and ceftriaxone (97.5%), cephalexin (92.5%), ampicillin (77.5%), amoxicillin/clavulanic acid (62.5%), with somewhat lower resistance for nalidixic acid (45%), ciprofloxacin (35%), and norfloxacin (32.5%) from fluoroquinolone group. Isolates showed considerable sensitivity to cefotaxime (65%) and levofloxacin (55%). All tested isolates carried blaTEM, blaSHV and ampC resistance genes, and this was associated with the phenotypic resistance too. Although some isolates showed phenotypic intermediate resistance to fluoroquinolones, or resistance to only one agent from this class, the qnrS (83.3%) has been detected with high frequency. The blaCTX-M (27.87%) and qepA (16.7%) showed the lowest occurrence and had been detected in isolates from broiler chickens only. The occurrence of these resistant E. coli serotypes in broiler chickens and ducks pose a potential threat to poultry industry, and constitutes a public health risk to human consumers, slaughterhouse and poultry packing plant workers due to dissemination of beta-lactam and fluoroquinolone resistant E. coli serotypes.

Aerococcous spp. thought to be a harmless pathogen, it is now recognized as a promising disease-causing microorganism. In the field of microbiology, aerococci are frequently confused with streptococci, leading to incorrect diagnoses. Antimicrobial resistance is globally increasing which is reflected in public health threat .Therefore, the current study was performed to evaluate the incidence of A. viridans in one hundred fecal swabs collected from broilers and layers farms in the Sharkia government, Egypt, and described its antibiotic resistance by VITEK system. Only one A. viridans isolate was identified from 100 samples. A. viridans isolate was susceptible to vancomycin, Trimethoprim/ sulfamethoxazole and linezolid, while, A. viridans isolate was resistant to Penicillin G, meropenem ,tetracycline and Ceftriaxone. As the first study in Egypt, this study concluded that MDR A. viridans of importance in public health which plays an essential role in diarrhea infection in poultry and is considered a hazard to human health.

Colibacillosis is one of the major problems in poultry houses caused by avian pathogenic Escherichia coli (APEC) which is the main cause of high morbidity and mortality rates in poultry houses leading to high economic losses. The present study was established to investigate the incidence of Escherichia coli (E. coli) infection in broiler birds suffering from yellowish-colored droppings, diarrhea, and soiled vent openings with or without septicemia signs. Aseptically, 200 samples were collected from the internal organs of diseased broiler chickens (liver, Heart, spleen, and yolk) at different farms in Ismailia governorate, 70 samples were E. coli positive with a 35% prevalence rate. The high prevalence of E. coli was recovered from yolk (40%), followed by liver (37.5%), heart (33.33%) and spleen (25%), respectively. A serological test was used to identify ten E. coli isolates as a slide agglutination test. The most predominant serotype was O44 (20%), O157 (20%), O119 (10%), O128 (10%), O78 (10%), O164 (10%), O145 (10%), O55 (10%).