Prevalence, molecular typing, and antimicrobial resistance of bacterial pathogens isolated from ducks

Multidrug resistant and multivirulent avian bacterial pathogens: tackling experimental leg disorders using phytobiotics and antibiotics alone or in combination

Locomotor disorders caused by multidrug-resistant (MDR) bacterial pathogens denote one of the most detrimental issues that collectively threaten the poultry industry leading to pronounced economic losses across the world. Hence, searching for effective alternatives, especially those extracted from plant origins became of great priority targeting a partial or complete replacement of chemical antimicrobials to tackle their developing resistance. Therefore, we aimed to determine the prevalence and antimicrobial resistance of Staphylococcus aureus (S. aureus), Salmonella species, Mycoplasma synoviae (M. synoviae), and Escherichia coli (E. coli) recovered from 500 broilers and ducks (250 each) with locomotor disorders in various farms in Dakahlia and Sharkia Governorates, Egypt. Additionally, we assessed, for the first time, the in vitro antimicrobial effectiveness of marjoram, garlic, ginger and cinnamon essential oils (EOs) against MDR and multivirulent bacterial isolates as well as the in vivo efficiency of the most effective antibiotics and EOs either separately or in combination in the treatment of experimentally induced poultry leg disorders. The overall prevalence rates of S. aureus, E. coli, Salmonella species, and M. synoviae were 54, 48, 36, and 2%, respectively. Salmonella species and S. aureus prevailed among ducks and broilers (36 and 76%, respectively). Notably, MDR was observed in 100, 91.7, 81.1, and 78.5% of M. synoviae, E. coli, Salmonella, and S. aureus isolates, respectively. Our in vitro results displayed that marjoram was the most forceful EO against MDR and multivirulent chicken vancomycin-resistant S. aureus (VRSA) and duck S. Typhimurium isolates. The current in vivo results declared that marjoram in combination with florfenicol or amoxicillin/clavulanic acid succeeded in relieving the induced duck and chicken leg disorders caused by S. Typhimurium and VRSA, respectively. This was evidenced by improvement in the clinical and histopathological pictures with a reduction of bacterial loads in the experimental birds. Our encountered successful in vitro and in vivo synergistic effectiveness of marjoram combined with florfenicol or amoxicillin/clavulanic acid recommends their therapeutic application for leg disorders and offers opportunities for reducing the antibiotics usage in the poultry industry.

Occurrence of Virulence Genes among Methicillin-Resistant Staphylococcus aureus Isolated from Subclinical Bovine Mastitis

The occurrence of Staphylococcus aureus-induced subclinical mastitis holds significant implications for public health. This specific microorganism possesses a wide array of pathogenic factors that enable it to adhere to, colonize, invade, and infect the host. The objective of the current study was to assess the prevalence of S. aureus, determine antimicrobial resistance patterns, and identify virulence genes of methicillin-resistant S. aureus (MRSA) strains responsible for subclinical mastitis in bovines. A total of 249 milk samples were collected from various farms in the district of Faisalabad. The presence of subclinical mastitis was assessed by using the California mastitis test. Positive milk samples (n = 100) were then subjected to standard microbiological techniques for isolation and identification of S. aureus. Antibiogram analysis was conducted by using the disc diffusion method to assess antimicrobial resistance. For the molecular detection of S. aureus and its virulence genes, the polymerase chain reaction (PCR) was performed with species-specific primers. The overall prevalence of S. aureus was found to be 40% (40/100), which was confirmed through molecular detection of the nuc gene in 40/40 (100%) of samples using PCR. Antimicrobial susceptibility tests indicated the highest susceptibility to vancomycin, sulfamethoxazole/trimethoprim, erythromycin, gentamicin, ciprofloxacin, and chloramphenicol, while the highest resistance rate was observed against tetracycline. Additionally, 30% of samples (12/40) tested positive for methicillin resistance. PCR analysis revealed that 100% of MRSA-tested isolates harbored the mecA and clfA genes. Furthermore, the MRSA isolates showed the presence of pvl, hla, hlb, sec, icaA, icaD, icaB, and icaC genes at rates of 92, 75, 67, 42, 42, 75, 8, and 25%, respectively. These findings underscore the need for stricter aseptic control in dairy farms to prevent disease transmission between animals and ensure the production of safe and uncontaminated food for human consumption.

First Description of Mergibacter septicus Isolated from a Common Tern (Sterna hirundo) in Germany

Mergibacter septicus (M. septicus), previously known as Bisgaard Taxon 40, is a recently described species within the Pasteurellaceae family. In this study, we present a M. septicus strain isolated from a common tern (Sterna hirundo) chick that died just after fledging from the Banter See in Wilhelmshaven, Germany. The recovered M. septicus strain underwent microbiological phenotypic characterization, followed by whole genome sequencing on Illumina and Nanopore platforms. Phenotypically, M. septicus 19Y0039 demonstrated resistance to colistin, cephalexin, clindamycin, oxacillin, and penicillin G. The genome analysis revealed a circular 1.8 Mbp chromosome without any extrachromosomal elements, containing 1690 coding DNA sequences. The majority of these coding genes were associated with translation, ribosomal structure and biogenesis, followed by RNA processing and modification, and transcription. Genetic analyses revealed that the German M. septicus strain 19Y0039 is related to the American strain M. septicus A25201T. Through BLAST alignment, twelve putative virulence genes previously identified in the M. septicus type strain A25201T were also found in the German strain. Additionally, 84 putative virulence genes distributed across nine categories, including immune modulation, effector delivery system, nutrition/metabolic factors, regulation, stress survival, adherence, biofilm, exotoxin, and motility, were also identified.

Common viral and bacterial avian respiratory infections: an updated review

Many pathogens that cause chronic diseases in birds use the respiratory tract as a primary route of infection, and respiratory disorders are the main leading source of financial losses in the poultry business. Respiratory infections are a serious problem facing the poultry sector, causing severe economic losses. Avian influenza virus, Newcastle disease virus, infectious bronchitis virus, and avian pneumovirus are particularly serious viral respiratory pathogens. Mycoplasma gallisepticum, Staphylococcus, Bordetella avium, Pasteurella multocida, Riemerella anatipestifer, Chlamydophila psittaci, and Escherichia coli have been identified as the most serious bacterial respiratory pathogens in poultry. This review gives an updated summary, incorporating the latest data, about the evidence for the circulation of widespread, economically important poultry respiratory pathogens, with special reference to possible methods for the control and prevention of these pathogens.

Ecological Distribution of Virulent Multidrug-Resistant Staphylococcus aureus in Livestock, Environment, and Dairy Products

Staphylococcus aureus is one of the most common causes of mastitis, leading to severe economic losses in the dairy industry. It is also zoonotic, with potential risks to public health. This study aimed to detect the occurrence of S. aureus-resistant strains isolated from cattle, buffalo, their environment, milk and dairy products; and to investigate the extent of animal, ecological, and food contamination by methicillin-resistant (MRSA) or enterotoxigenic S. aureus. Samples (n = 350) were collected from four animal (two cattle and two buffalo) farms, i.e., their environment. Thirty Karish cheese samples were collected from 10 markets in Mansoura, Egypt. S. aureus was detected in 17.9%, 17.6%, and 16.7% of samples collected from cattle, buffalo and Karish cheese, respectively. About 19% of isolated S. aureus strains carried the mecA gene. The distribution of the mecA gene was high in isolates from Karish cheese (60%), followed by samples collected from buffalo (16.2%) and cattle (16%). More than 34% of isolated S. aureus strains were enterotoxigenic, and the presence of enterotoxin genes was higher in isolates from Karish cheese (80%) than those from cattle (48%) and buffalo (18.9%). The most predominant enterotoxin gene among isolated S. aureus strains was the sea gene (26.9%), followed by sec (4.5%) and sed (3%) genes. Isolated strains were resistant to clindamycin (100%), kanamycin (97%), nalidixic acid (86.6%), cefotaxime (73.1%) sulphamethazole—trimethoprim (65.6%). Meanwhile, 95.5%, 94%, 86.6% and 77.7% of S. aureus strains were sensitive to ciprofloxacin, amikacin, imipenem and both cefoxitin and gentamycin, respectively. In conclusion, the presence of enterotoxigenic- and methicillin-resistant S. aureus strains in animals, their environment, and dairy products represents a public health concern, particularly in small-scale dairy farms in Egypt. To reduce the risk of infection of livestock and humans with resistant strains, strict regulations and guidelines for antimicrobial use in such a system are urgently required.

Effect of Co-infection of Low Pathogenic Avian Influenza H9N2 Virus and Avian Pathogenic E. coli on H9N2-Vaccinated Commercial Broiler Chickens

In the last 40 years, low pathogenic avian influenza virus (LPAIV) subtype H9N2 has been endemic in most Middle Eastern countries and of course Egypt which is one of the biggest poultry producers in the middle east region. The major losses with the H9N2 virus infections come from complicated infections in commercial broiler chickens, especially E. coli infection. In this work, 2,36,345 Arbor acres broiler chickens from the same breeder flock were placed equally in four pens, where two pens were vaccinated against LPAIV of subtype H9N2 virus, and the other two pens served as non-vaccinated controls. All were placed on the same farm under the same management conditions. A total of twenty birds from each pen were moved to biosafety level−3 chicken isolators (BSL-3) on days 21 and 28 of life and challenged with LPAIV-H9N2 or E. coli. Seroconversion for H9N2 was evaluated before and after the challenge. The recorded results revealed a significant decrease in clinical manifestations and virus shedding in terms of titers of shedding virus and number of shedders in vaccinated compared to non-vaccinated chickens. In groups early infected with LPAIV-H9N2 virus either vaccinated or not vaccinated, there was no significant difference in clinical sickness or mortalities in both groups, but in late infection groups with H9N2 alone, non-vaccinated infected group showed significantly higher clinical sickness in comparison with infected vaccinated group but also without mortality. In groups co-infected with E. coli (I/M) and H9N2, it showed 100% mortalities either in vaccinated or non-vaccinated H9N2 groups and thus reflect the high pathogenicity of used E. coli isolates, whereas in groups co-infected with E. coli (per os to mimic the natural route of infection) and LPAIV-H9N2, mortality rates were significantly higher in non-vaccinated groups than those vaccinated with H9N2 vaccine (15 vs. 5%). In conclusion, the use of the LPAIV H9N2 vaccine has significantly impacted the health status, amount of virus shed, and mortality of challenged commercial broilers, as it can minimize the losses and risks after co-infection with E. coli (orally) and LPAIV-H9N2 virus under similar natural route of infection in commercial broilers.

Efficacy of the Newcastle Disease Virus Genotype VII.1.1-Matched Vaccines in Commercial Broilers

Class II genotype VII Newcastle disease viruses (NDV) are predominant in the Middle East and Asia despite intensive vaccination programs using conventional live and inactivated NDV vaccines. In this study, the protective efficacies of three commercial vaccine regimes involving genotype II NDV, recombinant genotype VII NDV-matched, and an autogenous velogenic NDV genotype VII vaccine were evaluated against challenge with velogenic NDV genotype VII (accession number MG029120). Three vaccination regimes were applied as follows: group-1 received inactivated genotype II, group-2 received inactivated recombinant genotype VII NDV-matched, and group-3 received velogenic inactivated autogenous NDV genotype VII vaccines given on day 7; for the live vaccine doses, each group received the same live genotype II vaccine. The birds in all of the groups were challenged with NDV genotype VII, which was applied on day 28. Protection by the three regimes was evaluated after infection based on mortality rate, clinical signs, gross lesions, virus shedding, seroconversion, and microscopic changes. The results showed that these three vaccination regimes partially protected commercial broilers (73%, 86%, 97%, respectively, vs. 8.6% in non-vaccinated challenged and 0% in non-vaccinated non-challenged birds) against mortality at 10 days post-challenge (dpc). Using inactivated vaccines significantly reduced the virus shedding at the level of the number of shedders and the amount of virus that was shed in all vaccinated groups (G1-3) compared to in the non-vaccinated group (G-4). In conclusion, using closely genotype-matched vaccines (NDV-GVII) provided higher protection than using vaccines that were not closely genotype-matched and non-genotype-matched. The vaccine seeds that were closely related to genotype VII.1.1 provided higher protection against challenge against this genotype since it circulates in the Middle East region. Updating vaccine seeds with recent and closely related isolates provides higher protection.

Molecular characterization of Toll-like receptor type-3 in mallard duck and its response to Newcastle disease virus infection

Toll-like receptors (TLRs), type I transmembrane pattern recognition receptors (PRRs), are composed of the extracellular domain that is implicated in the recognition of microbial products and initiates the innate and adaptive immune response. Previous reports on TLRs in birds showed significant levels of inter- and intraspecific genetic variation. Little is known about the structure and function of the avian immune system, especially waterfowl species. This work aimed to identify and clone Anas platyrhynchos (mallard duck) TLR-3 (dTLR-3) and its expression level following challenge with velogenic Newcastle disease virus (NDV) as a model for waterfowl species. The mallard duck TLR-3 full-length cDNA sequence had been cloned, which consisted of 2457 nucleotides. The translated amino acid sequence showed identity degree as 97% with Muscovy duck, 95% with geese, 89% with helmeted guineafowls, 88% with the chickens TLR-3 gene, 82% with turkey TLR-3, and 79% with zebra finch, while it showed 54% with human one; the analysis data suggested that the new sequence is probably homologous to vertebrates' TLR-3. The predicted protein encoded by the duck dTLR-3 mRNA sequence is composed of 819 amino acids. Analysis of the deduced amino acid sequence indicated that dTLR-3 has typical structural features and contains the main components of proteins in the TLR family. The dTLR-3 expressed in almost all examined tissues of mallard duck following quantitative real-time polymerase chain reaction (qPCR) analysis and using B-actin as a housekeeping gene. To check the functionality of the receptor and its role in viral infection, we evaluate the expression level in different tissues and its changes following NDV infection. The results showed significant (P < 0.05) upregulated in the brain at 24 h (1.84-fold), reached a peak at 48 h (4.82-fold), and recovered to normal levels at 72 h post-infection. These results indicate a complete and functional dTLR-3 that is orthologous to other vertebrate receptors with its potential role in early response against viral infection in mallard duck species.

Virulence attitude estimation of Pasteurella multocida isolates in embryonated chicken eggs

A total of 220 birds of age ranging from 3 to 14 weeks old were collected from several backyards and different farms in Sharkia Governorate, Egypt, and surveyed for the presence of fowl cholera. Twenty Pasteurella multocida from chickens (15/145, 10%) and ducks (5/75, 6%) were bacteriologically isolated, and it was shown that the infection was significantly related to age and breed. Capsular typing, using multiplex polymerase chain reaction (PCR), demonstrated that all strains were type A (100%). Disk diffusion assay towards ten antimicrobials revealed high susceptibilities to amikacin, doxycycline, chloramphenicol, and neomycin with varying degrees. Doxycycline was effective at the lowest concentration (MIC 0.125-1 µg/ml). Multidrug resistance was detected with a percentage of 25%. Multidrug-resistant isolates (five isolates) were subjected to study their pathogenicity in embryonated chicken eggs (ECE). The results showed a variation in indices between different dilutions of the tested strains. The resulting pathogenicity indices showed significant differences (P < 0.05) according to the origin and dilution of the isolate. From the original inoculum to 10^-4 dilutions, the mortality of inoculated embryos occurred within 1-2 days with pathological findings, including maceration and lesions on chorioallantoic membrane (CAM). From dilutions ranging from 10^-5 to 10^-9, no death occurred until 7 days post-inoculation, but a variation in the lesions on CAM was observed. In conclusion, P. multocida serogroup A could be intensely pathogenic for mature chickens thus causing considerable economic losses, and PCR provides a suitable technique for early and rapid diagnosis of fowl cholera.

Efficiency evaluation of some novel disinfectants and anti-bacterial nanocomposite on zoonotic bacterial pathogens in commercial Mallard duck pens for efficient control

OBJECTIVE

This work aimed to detect the frequency of pathogenic bacteria of zoonotic importance in ducks' dropping, their surrounding environment, and farmworkers in contact with them. Furthermore, the susceptibility pattern of isolated bacteria to antimicrobial drugs and the efficiency of disinfectants (CID 20, Durak® plus, and hydrogen peroxide (H2O2), nano zinc oxide (ZnO NPs), and hydrogen peroxide loaded nano zinc oxide (H2O2/ZnO NPs) composites against isolated bacteria were evaluated.

MATERIALS AND METHODS

A total of 271 samples were collected from duck pens, including 35 fecal droppings, 200 environmental samples, and 36 from the hands of pen workers for isolation and identification of bacterial strains using standard microbiological procedures. After that, the antibiotic sensitivity testing of 40 bacterial isolates was carried out using disk diffusion assay. ZnO NPs and H2O2/ZnO NPs were characterized using Fourier-transform infrared spectrum and high-resolution transmission electron microscopy. The efficacy of disinfectants and nanocomposites was evaluated against enteropathogenic bacteria using the broth macro-dilution method.

RESULTS

The results showed that the overall prevalence of pathogenic bacteria in duck pens was 62.73. The highest isolation rate was detected in duck fecal droppings (100%), while Escherichia coli was found to be the most isolated pathogen (56.47%), followed by Pseudomonas aeruginosa (21.8%), Proteus mirabilis (15.29), and Salmonella species (6.47%). Multidrug resistance (MDR) was detected in the majority of bacterial isolates. The efficiency of CID 20 and Durak® plus disinfectants against all bacterial isolates was highly susceptible (100%) after 120 min of exposure time compared to the effectiveness of H2O2 on enteropathogenic bacteria which did not exceeded 60% at 5% concentration. Meanwhile, the sensitivity of Salmonella spp. to Durak® plus did not exceeded 80%.

CONCLUSION

The duck fecal droppings are the primary source of bacterial isolates. MDR isolates were susceptible to both CID 20 and Durak® plus disinfectants after 120 min of exposure time at a concentration of 1:100 ml. Besides, H2O2/ZnO NPs composite proved its lethal effect against all testing strains at 0.02 mg/ml after 120 min of exposure. Strict biosecurity guidelines are required to mitigate and prevent the transmission of potentially zoonotic pathogens through the farm environment and/or duck droppings.

Virulence Determinants and Multidrug Resistance of Escherichia coli Isolated from Migratory Birds

Migratory birds are carriers of multidrug resistant pathogenic Escherichia coli. However, their roles in the dissemination of these resistant pathogens are still being neglected in Bangladesh. The present study was therefore carried out to detect multidrug resistant E. coli. In addition, these isolates were also screened for the presence of avian pathogenic E. coli (APEC)-associated virulence genes. A total of 66 fecal matter samples of migratory birds were screened. E. coli were isolated and identified by culturing and biochemical tests followed by polymerase chain reaction (PCR). APEC-associated virulence genes were detected by PCR. Disk diffusion assays were employed to investigate antibiogram profiles. Bivariate analysis was performed to assess correlations in resistance patterns between antimicrobials and to assess associations between virulence genes of E. coli. Among the 66 samples assessed by PCR, 55 (83.33%) were found positive for E. coli. Of these 55 isolates, the APEC-associated virulence gene fimC was detected in 67.27% of the isolates, which was significantly higher than in the cases of iucD (29.09%) and papC (5.45%) genes. In addition, three isolates were found positive for all three virulence genes, while 23 and 12 isolates were positive for one and two virulence genes respectively. In the bivariate analysis, significant associations were detected between fimC and iucD virulence genes. Using the antibiogram, all E. coli isolates were found to be multidrug resistant (MDR). The isolates exhibited 100% resistance against ampicillin and erythromycin in addition to varying percentages of resistance against streptomycin, tetracycline, ciprofloxacin, and chloramphenicol. Highly positive correlations between tetracycline and ciprofloxacin, chloramphenicol and ciprofloxacin, chloramphenicol and tetracycline were observed by bivariate analysis. To the best of our knowledge, this is the first study that reports APEC-associated virulence genes of MDR E. coli from migratory birds in Bangladesh. Results indicate that migratory birds are reservoirs of MDR E. coli isolates carrying APEC-associated virulence genes, which can seriously contribute to the development of human and animal diseases.

Virulence-determinants and antibiotic-resistance genes of MDR-E. coli isolated from secondary infections following FMD-outbreak in cattle

This study aimed to evaluate the prevalence, multidrug-resistance traits, PCR-detection of virulence, and antibiotic-resistance genes of E. coli isolated from secondary infections following FMD-outbreak in cattle. A total of 160 random samples were gathered from private dairy farms in Damietta Province, Egypt. The specimens were subjected to bacteriological examination, serotyping, congo-red binding assay, antibiogram-testing, and PCR-monitoring of virulence-determinant genes (tsh, phoA, hly, eaeA, sta, and lt) as well as the antibiotic-resistance genes (bla_TEM, bla_KPC, and bla_CTX). The prevalence of E. coli was 30% (n = 48) distributed in 8 serogroups (40/48, 83.3%), while 8 isolates (8/48, 16.6%) were untypable. Besides, 83.3% of the examined isolates were positive for CR-binding. The tested strains harbored the virulence genes phoA, hly, tsh, eaeA, sta, and lt with a prevalence of 100% and 50%, 45.8%, 25%, 8.4%, and 6.2%, respectively. Furthermore, 50% of the recovered strains were multidrug-resistant (MDR) to penicillins, cephalosporins, and carbapenems, and are harboring the bla_TEM, bla_CTX, and bla_KPC genes. Moreover, 25% of the examined strains are resistant to penicillins, and cephalosporins, and are harboring the bla_TEM and bla_CTX genes. To the best of our knowledge, this is the first report concerning the E. coli secondary bacterial infections following the FMD-outbreak. The emergence of MDR strains is considered a public health threat and indicates complicated treatment and bad prognosis of infections caused by such strains. Colistin sulfate and levofloxacin have a promising in vitro activity against MDR-E. coli.

Comparison of the Effectiveness of Two Different Vaccination Regimes for Avian Influenza H9N2 in Broiler Chicken

Low pathogenic avian influenza virus is one of the major threats that has been affecting the poultry industry in the Middle East region for decades. Attempts to eradicate this disease have failed. Currently, there are commercial vaccines that are either imported or produced locally from recently circulating isolates of H9N2 in Egypt and Middle Eastern countries. This present work focused on comparing the effectiveness of two vaccines belonging to these categories in Egypt. Two commercial broiler flocks (Cobb-500 Broiler) with maternally derived immunity (MDA) against H9N2 virus were employed and placed under normal commercial field conditions or laboratory conditions. Immunity was evaluated on the basis of detectable humoral antibodies against influenza H9N2 virus, and challenge was conducted at 28 days of life using a recent wild H9N2 virus. The results showed that vaccination on the 7th day of life provided significantly higher immune response in both vaccine types, with significantly lower virus shedding compared to vaccination at day 1 of life, regardless of field or laboratory conditions. In addition, the vaccine produced from a recent local H9N2 isolate (MEFLUVAC-H9-16) provided a significantly higher humoral immune response under both field and laboratory conditions, as measured by serology and virus shedding (number of shedders and amount of shedding virus), being significantly lower following challenge on the 28th day of life, contrary to the imported H9 vaccine. In conclusion, use of H9N2 vaccine at 7 days of life provided a significantly higher protection than vaccination at day 1 of life in birds with MDA, suggesting vaccination regimes between 5-8-days of life for broiler chicks with MDA. Moreover, use of a vaccine prepared from a recently circulating H9N2 virus showed significantly higher protection and was more suitable for birds in the Middle East.

Methicillin-Resistant Staphylococcus aureus (MRSA): One Health Perspective Approach to the Bacterium Epidemiology, Virulence Factors, Antibiotic-Resistance, and Zoonotic Impact

Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen and a historically emergent zoonotic pathogen with public health and veterinary importance. In humans, MRSA commonly causes severe infectious diseases, including food poisoning, pyogenic endocarditis, suppurative pneumonia, otitis media, osteomyelitis, and pyogenic infections of the skin, soft tissues. In the horse, MRSA could cause a localized purulent infection and botryomycosis; in cattle and ewe, localized pyogenic infection and severe acute mastitis with marked toxemia; in sheep, abscess disease resembles caseous lymphadenitis caused by anaerobic strains; in dogs and cats, pustular dermatitis and food poisoning; in pig, exudative epidermatitis “greasy pig disease; in birds, MRSA causes bumble-foot. The methicillin resistance could be determined by PCR-based detection of the mecA gene as well as resistance to cefoxitin. In Egypt, MRSA is one of the important occasions of subclinical and clinical bovine mastitis, and the prevalence of MRSA varies by geographical region. In this review, we are trying to illustrate variable data about the host susceptibility, diseases, epidemiology, virulence factors, antibiotic resistance, treatment, and control of MRSA infection.

Genes Encoding the Virulence and the Antimicrobial Resistance in Enterotoxigenic and Shiga-Toxigenic E. coli Isolated from Diarrheic Calves

Calf diarrhea is one of the considerable infectious diseases in calves, which results in tremendous economic losses globally. To determine the prevalence of Shiga-toxigenic E. coli (STEC) and Enterotoxigenic E. coli (ETEC) incriminated in calf diarrhea, with special reference to Shiga- toxins genes (stx1 and stx2) and enterotoxins genes (lt and sta) that govern their pathogenesis, as well as the virulence genes; eaeA (intimin) and f41(fimbrial adhesion), and the screening of their antibiogram and antimicrobial resistance genes; aadB, sul1, and bla-TEM, a total of 274 fecal samples were collected (April 2018–Feb 2019) from diarrheic calves at different farms in El-Sharqia Governorate, Egypt. The bacteriological examination revealed that the prevalence of E. coli in diarrheic calves was 28.8%. The serotyping of the isolated E. coli revealed 7 serogroups; O₂₆, O₁₂₈, O₁₁₁, O₁₂₅, O₄₅, O₁₁₉ and O₉₁. Furthermore, the Congo red binding test was carried out, where 89.8% of the examined strains (n = 71) were positive. The antibiogram of the isolated strains was investigated; the majority of E. coli serotypes exhibit multidrug resistance (MDR) to four antimicrobial agents; neomycin, gentamycin, streptomycin, and amikacin. Polymerase chain reaction (PCR) was used to detect the prevalence of the virulence genes; stx1, stx2 lt, sta, f41 and eaeA, as well as the antimicrobial resistance genes; aadB, sul1, and bla-TEM. The prevalence of STEC was 20.2% (n = 16), while the prevalence of ETEC was 30.4% (n = 24). Briefly, the Shiga toxins genes; stx1 and stx2, are the most prevalent virulence genes associated with STEC, which are responsible for the pathogenesis of the disease and helped by the intimin gene (eaeA). In addition, the lt gene is the most prevalent enterotoxin gene accompanied by the ETEC strains, either alone or in combination with sta and/or f41 genes. The majority of pathogenic E. coli incriminated in calf diarrhea possesses the aadB resistance gene, followed by the sul1 gene. Enrofloxacin, florfenicol, amoxicillin-clavulanic acid, and ampicillin-sulbactam, are the most effective antimicrobial agents against the isolated STEC and ETEC strains.

Prevalence, the antibiogram and the frequency of virulence genes of the most predominant bacterial pathogens incriminated in calf pneumonia

The purpose of this study was to investigate the prevalence, antibiotic resistance and certain virulence genes of the most predominant bacterial pathogens causing BRD. A total of 225 calves; 55 apparently healthy and 170 diseased; were sampled. Bacteriological examination, antimicrobial susceptibility testing and PCR based detection of some virulence genes were performed. In addition, the serotyping of E. coli was performed using the slide agglutination test. The most predominant bacterial pathogens retrieved from apparently healthy calves were E. coli (16.4%) and S. aureus (10.9%), and in pneumonic calves were E. coli (23.5%), P. vulgaris (12.4%) and S. aureus (11.8%). The most prevalent virulence gene in E. coli was the fimH gene (100%), followed by eaeA gene (24.5%) and hly gene (20.4%). All the examined S. aureus strains harbored spa and coa genes; likewise, all P. multocida strains harbored toxA gene. The majority of the isolated strains displayed remarkable sensitivity to norfloxacin and enrofloxacin; furthermore, the retrieved E. coli strains exhibited multidrug-resistance to gentamicin, erythromycin, streptomycin and trimethoprim-sulphamethoxazole, in addition, the isolated S. aureus and P. aeruginosa strains showed multidrug-resistance to amoxicillin, ampicillin and tetracycline. E. coli serogroups including O18, O143, O1, and O6 were retrieved from pneumonic calves as the first report in Egypt. In conclusion, the synergism between the conventional and genotypic analysis is an effective gadget for the characterization of bacterial pathogens causing BRD. Continuous surveillance of antimicrobial susceptibility is essential to select the drug of choice due to the development of multidrug-resistant strains.

Prevalence, Antimicrobial Resistance Profiles, Virulence and Enterotoxins-Determinant Genes of MRSA Isolated from Subclinical Bovine Mastitis in Egypt

Subclinical mastitis caused by Staphylococcus aureus has worldwide public health significance. Here, we aimed to determine the prevalence of S. aureus, antimicrobial resistance profiles, and the virulence and enterotoxins determinant genes of MRSA strains that caused subclinical bovine mastitis. Milk samples were collected from 120 lactating animals (50 buffaloes and 70 dairy cattle) from different farms located in Ismailia Province (Egypt). The collected samples were investigated for subclinical mastitis using a California mastitis test. The total prevalence of S. aureus was 35.9% (84/234) with 36.3% (53/146) in cattle and 31% (31/88) in buffaloes. Antimicrobial susceptibility testing showed that 35.7% (30/84) of the isolated strains were resistant to cefoxitin, defined as methicillin-resistant S. aureus (MRSA), with 37.7% (20/53) in cattle and 32.2% (10/31) in buffaloes. Using PCR, 100% of the tested strains harbored coa and mecA genes, while 86.6% were positive for spa gene, with remarkable gene size polymorphism. Additionally, 10% of the tested strains contained the pvl gene. Further, using multiplex PCR, 26.6% of the tested samples had sea gene, two strains had sec gene and only one strain had sea and sec genes. The seb and sed genes were absent in the tested strains. In conclusion, mecA, coa and spa virulence genes were widely distributed in MRSA strains isolated from bovine milk, whereas the sea gene was the most predominant enterotoxin gene. Notably, this is the first report that emphasizes the prevalence of pvl gene of MRSA isolated from bovine milk in Egypt.

Molecular Typing, Antibiogram and PCR-RFLP Based Detection of Aeromonas hydrophila Complex Isolated from Oreochromis niloticus

Motile Aeromonas septicemia is a common bacterial disease that affects Oreochromis niloticus and causes tremendous economic losses globally. In order to investigate the prevalence, molecular typing, antibiogram and the biodiversity of Aeromonas hydrophila complex, a total of 250 tilapia (Oreochromis niloticus) were collected randomly from 10 private tilapia farms (25 fish/farm) at El-Sharkia Governorate, Egypt. The collected fish were subjected to clinical and bacteriological examinations. The majority of infected fish displayed ulcerative necrosis, exophthalmia, and internal signs of hemorrhagic septicemia. The prevalence of A. hydrophia complex was 13.2%, where the liver was the most predominant affected organ (54.1%). Polymerase chain reaction (PCR) was used to verify the identification of A. hydrophila complex using one set of primers targeting gyrB as well as the detection of virulent genes (aerA, alt, and ahp). All isolates were positive for the gyrB-conserved gene and harbored aerA and alt virulence genes. However, none of those isolates were positive for the ahp gene. The antimicrobial sensitivity was carried out, where the recovered strains were completely sensitive to ciprofloxacin and highly resistant to amoxicillin. All retrieved strains showed the same phenotypic characteristics and were identical based on the restriction fragment length polymorphism (RFLP). Experimentally challenged fish presented a high mortality rate (76.67%) and showed typical signs as in naturally infected ones. In conclusion, the synergism of phenotypic and genotypic characterization is a valuable epidemiological tool for the diagnosis of A. hydrophila complex. RFLP is a fundamental tool for monitoring the biodiversity among all retrieved strains of A. hydrophia.

Pasteurellaceae members with similar morphological patterns associated with respiratory manifestations in ducks

Aim:

A total of 112 freshly dead ducks aged from 2 to 20 weeks old with a history of respiratory manifestations were investigated for the implication of Pasteurellaceae family members.

Materials and Methods:

Isolation and identification to the family level were conducted by conventional bacteriological methods, including microscopic examination and biochemical characterization. Identification to the species level was conducted by polymerase chain reaction (PCR) and analytical profile index (API) 20E kits.

Results:

Conventional bacteriological isolation and biochemical characterization revealed the infection of 16/112 examined birds with a prevalence rate of 14.3%. PCR confirmed the detection of Pasteurellaceae family conserved genes RpoB and Bootz in 16/16 (100%) isolates. PCR was also used for genus and species identification of the isolated Pasteurellaceae members; the results revealed that 5/16 (31.3%) of isolates were Gallibacterium anatis and 2/16 of isolates (12.5%) were Pasteurella multocida. Riemerella anatipestifer, Mannheimia haemolytica, and Avibacterium paragallinarum were not detected by PCR. Biotyping by API 20E successfully identified 5/16 (31.3%) isolates that could not be typed by PCR and confirmed their belonging to Pasteurella pneumotropica. Neither the available PCR primer sets nor API 20E succeeded for species identification of 4/16 (25%) isolates. Antibiotic susceptibility profiling of isolates revealed that 16/16 (100%) of isolates demonstrated multidrug resistance (MDR) phenotypes. Moreover, 16/16 (100%) of isolates demonstrated a phenotypic resistance pattern to neomycin.

Conclusion:

Combined genotypic, phenotypic, biotyping, and virulence characterizations are required for laboratory identification of pathogenic Pasteurellaceae. Moreover, P. multocida was not the prevailed member implicated in respiratory problems in ducks as P. pneumotropica, G. anatis, and unidentified strains were involved with higher prevalence. Chloramphenicol and ampicillin demonstrated the highest in vitro effects on the studied Pasteurellaceae. Furthermore, the prevalence of multidrug-resistant isolates signified the demand to implement targeted surveillance in the ducks’ production sector, and MDR survey in poultry sectors in Egypt to apply effective control measures.

The occurrence of the multidrug resistance (MDR) and the prevalence of virulence genes and QACs resistance genes in E. coli isolated from environmental and avian sources

Colibacillosis is a major disease affecting poultry leads to high morbidity and mortality which causing tremendous economic losses worldwide. These economic disparities are amplified among low and middle-income where sanitation and hygiene are challenged by the increasing demand for quality sources of animal protein. With a view to investigating the prevalence of virulence genes and QACs resistance genes as well as monitoring the antibiogram of E. coli strains, a total of 368 specimens were collected from diseased broiler chickens (n = 226) and environmental sources (n = 142) at large-scale poultry farms in Ismailia Governorate, Egypt. The bacteriological examination proved that E. coli prevalence was 26.76% and 50.44% in the farm environment and diseased broilers, respectively. In tandem, the isolated E. coli strains were serogrouped, determining the most common serotypes were O78, O1:H7, O91:H21 and O126. Isolates were tested for antimicrobial susceptibility against 12 antibiotics, screened for 4 virulence genes (iss, papC, eaeA, and cfaI), and screened for 3 QACs resistance genes (qacEΔ1, qacA/B, and qacC/D). All the tested strains were positive for iss and papC genes, only 20.3% of the tested strains were positive for eaeA gene, moreover, the examined strains were negative to CFAI gene. Furthermore, all the tested strains were positive for qacEΔ1, qacA/B, and qacC/D genes. In conclusion; virulence genes (iss, papC) as well as QACs resistance genes are common in avian Pathogenic E. coli and environmental strains and are mainly associated with multi-drug resistance phenomena.

Experimental evidence that symbiotic bacteria produce chemical cues in a songbird

Symbiotic microbes that inhabit animal scent glands can produce volatile compounds used as chemical signals by the host animal. Though several studies have demonstrated correlations between scent gland bacterial community structure and host animal odour profiles, none have systematically demonstrated a causal relationship. In birds, volatile compounds in preen oil secreted by the uropygial gland serve as chemical cues and signals. Here, we tested whether manipulating the uropygial gland microbial community affects chemical profiles in the dark-eyed junco (Junco hyemalis). We found an effect of antibiotic treatment targeting the uropygial gland on both bacterial and volatile profiles. In a second experiment, we cultured bacteria from junco preen oil, and found that all of the cultivars produced at least one volatile compound common in junco preen oil, and that most cultivars produced multiple preen oil volatiles. In both experiments, we identified experimentally generated patterns in specific volatile compounds previously shown to predict junco reproductive success. Together, our data provide experimental support for the hypothesis that symbiotic bacteria produce behaviourally relevant volatile compounds within avian chemical cues and signals.