Serovar Identification, Antimicrobial Sensitivity, and Virulence of Avibacterium paragallinarum Isolated from Chickens in Thailand

Case reports involving coinfection with Avibacterium paragallinarum and Ornithobacterium rhinotracheale in broiler chickens and Avibacterium endocarditis in broiler breeding hens in Poland

ABSTRACTThe study describes three clinical cases of infection with Avibacterium spp.. In case no. 1, respiratory clinical signs and high mortality (0.7-4.2% daily; total 21.2%) in Ross 308 broiler chickens were shown to be caused by coinfection with sequence type 9 of O. rhinotracheale presumptive serotype A and A. paragallinarum presumptive serotype B. The identical (pulsed-field gel electrophoresis) restriction pattern (pulsotype) of seven A. paragallinarum isolates indicated that infectious coryza in broilers was caused by the same clone. In cases 2 and 3, sudden increased deaths in Ross 308 broiler breeders (especially males) with lesions in the endocardium (valvular or mural endocarditis) were shown to be caused by A. endocarditis. Among nine antibiotics tested, florfenicol was the only antibiotic to which all A. paragallinarum and O. rhinotracheale isolates were susceptible. Out of the eight antibiotics tested, 11 A. endocarditis isolates from both clinical cases of infective endocarditis were susceptible to penicillin, amoxicillin, doxycycline and florfenicol. The A. endocarditis isolates tested in both clinical cases had different PFGE patterns (pulsotypes), but identical within a case. The causes of infectious coryza and infective endocarditis in the cases presented have not been determined. In the prevention of infectious diseases in large-scale livestock farming, it is very important to follow the rules of biosecurity.

Genomic Characterization and Safety Assessment of Bifidobacterium breve BS2-PB3 as Functional Food

Our group had isolated Bifidobacterium breve strain BS2-PB3 from human breast milk. In this study, we sequenced the whole genome of B. breve BS2-PB3, and with a focus on its safety profile, various probiotic characteristics (presence of antibiotic resistance genes, virulence factors, and mobile elements) were then determined through bioinformatic analyses. The antibiotic resistance profile of B. breve BS2-PB3 was also evaluated. The whole genome of B. breve BS2-PB3 consisted of 2,268,931 base pairs with a G-C content of 58.89% and 2,108 coding regions. The average nucleotide identity and whole-genome phylogenetic analyses supported the classification of B. breve BS2-PB3. According to our in silico assessment, B. breve BS2-PB3 possesses antioxidant and immunomodulation properties in addition to various genes related to the probiotic properties of heat, cold, and acid stress, bile tolerance, and adhesion. Antibiotic susceptibility was evaluated using the Kirby-Bauer disk-diffusion test, in which the minimum inhibitory concentrations for selected antibiotics were subsequently tested using the Epsilometer test. B. breve BS2-PB3 only exhibited selected resistance phenotypes, i.e., to mupirocin (minimum inhibitory concentration/MIC >1,024 μg/ml), sulfamethoxazole (MIC >1,024 μg/ml), and oxacillin (MIC >3 μg/ml). The resistance genes against those antibiotics, i.e., ileS, mupB, sul4, mecC and ramA, were detected within its genome as well. While no virulence factor was detected, four insertion sequences were identified within the genome but were located away from the identified antibiotic resistance genes. In conclusion, B. breve BS2-PB3 demonstrated a sufficient safety profile, making it a promising candidate for further development as a potential functional food.

Pathogenicity of Avibacterium paragallinarum Strains from Peru and the Selection of Candidate Strains for an Inactivated Vaccine

Worldwide, Avibacterium paragallinarum is the aetiological agent of infectious coryza in poultry. Vaccines are the best means of control, helping reduce clinical signs and colonization of this bacterium. Most vaccines are based on international reference strains, or, lately, regional strains, but, generally, without any information regarding their virulence. The characterization of the pathogenicity of 24 Av. paragallinarum strains of the three Page serogroups, including four variant strains of serogroup B, all isolated from infectious coryza outbreaks in Peru, was performed. After experimental inoculation into the infraorbital sinuses, information regarding their capacity to induce infectious coryza typical clinical signs, spreading, and colonization was recorded. Furthermore, after intraperitoneal inoculation, septicaemia and death were registered. Differences among strains in these parameters were observed, even within strains from the same serogroup. Finally, the four most pathogenic strains, one from each serogroup, were chosen to formulate an experimental vaccine that was tested successfully against homologous challenges in reducing clinical signs and colonization in vaccinated birds compared to unvaccinated ones. This is the first time that Av. paragallinarum strains from Peru were studied thoroughly for their virulence in a search for improving vaccine formulation.

Novel NAD-independent Avibacterium paragallinarum: Isolation, characterization and molecular identification in Iran

BACKGROUND

Infectious coryza (IC) is an invasive upper respiratory disease caused by Avibacterium paragallinarum that affects birds, particularly chickens. The objective of this study is to isolate, characterize and molecularly identify the bacterium A. paragallinarum in poultry birds, as well as to determine its antibiotic sensitivity and resistance.

METHODS

A total of 10 chickens from four different Iranian farms with typical IC symptoms were used in this study. The nasal swabs were streaked onto chocolate agar plates and blood agar plates and incubated at 37°C in 5% CO2 for 24 to 48 h. As part of the identification of bacteria, bacteriological observations and polymerase chain reaction (PCR) testing are conducted. The antibiotic sensitivity tests were also performed using the disk diffusion method against A. paragallinarum and the prevalence in different farms was determined.

RESULTS

By using biochemical assays and PCR analyses, seven strains of A. paragallinarum were isolated from samples of four chicken farms with typical IC clinical signs. Most isolates (4/7) showed the typical requirement for nicotinamide adenine dinucleotide (NAD) and an enriched CO2 atmosphere for growth. Three of the seven strains of A. paragallinarum were found to be novel NAD-independent under anaerobic conditions. There was one biochemical biovar identified in terms of carbohydrate fermentation patterns, although changes in maltose carbohydrate fermentation patterns were detected in the No. 5 strain. All isolates were sensitive to gentamicin and spectinomycin. Three novel NAD-independent strains (Nos.1, 5 and 7) were found to be multidrug-resistant (MDR) and resistant to at least three classes of antibiotics. There was greater antibiotic resistance in the three NAD-independent isolates than in normal NAD-dependent bacteria.

CONCLUSION

By discovering NAD-independent forms of A. paragallinarum, these species have a greater range than previously believed. A clear, cautious approach should be taken in diagnosing and possibly controlling IC.

Isolation, Serovar Identification, and Antimicrobial Susceptibility of Avibacteriumparagallinarum from Chickens in China from 2019 to 2020

Infectious coryza is an acute infectious respiratory disease in chickens that is caused by Avibacterium paragallinarum (A. paragallinarum). Infectious coryza has major economic effects due to decreased egg production in growing birds and slowed growth in broilers. In this study, we isolated and identified 40 strains of A. paragallinarum from chickens that showed typical clinical signs of coryza in part of China from 2019 to 2020. Using a hemagglutination-inhibition test, 11 isolates were identified as serovar A, 10 isolates were identified as serovar B, and 19 isolates were identified as serovar C. Antimicrobial sensitivity tests showed that high minimum inhibitory concentration (MIC) values were encountered for compounds sulfamethoxine sodium and oxytetracycline hydrochloride. Especially, of the 40 A. paragallinarum isolates, 30% had an MIC value of compound sulfamethoxine sodium of 64 μg/mL, 10% of 128 μg/mL, and 15% of 256 μg/mL. For oxytetracycline hydrochloride, 85% of isolates showed MIC values of 64 μg/mL or more. Excitingly, the MIC values of β-lactamase (amoxicillin, ampicillin, and ceftiofur) were low, with 77.5%, 70%, and 92.5% of isolates having an MIC value of ≤1 μg/mL, respectively. Our results may provide a reference for the treatment of infectious coryza.

Assessment of animal diseases caused by bacteria resistant to antimicrobials: Poultry

In this opinion, the antimicrobial‐resistant bacteria responsible for transmissible diseases that constitute a threat to poultry health have been assessed. The assessment has been performed following a methodology based on information collected by an extensive literature review and expert judgement. Details of the methodology used for this assessment are explained in a separate opinion. A global state of play is provided for: Avibacterium (Haemophilus) paragallinarum, Bordetella avium, Clostridium perfringens, Enterococcus faecalis and Enterococcus cecorum, Erysipelothrix rhusiopathiae, Escherichia coli, Gallibacterium spp., Mycoplasma synoviae, Ornithobacterium rhinotracheale, Pasteurella multocida, Riemerella anatipestifer and Staphylococcus aureus. Among those bacteria, EFSA identified Escherichia coli, Enterococcus faecalis and Enterococcus cecorum with ≥ 66% certainty as being the most relevant antimicrobial resistant bacteria in the EU based on the available evidence. The animal health impact of these most relevant bacteria, and their eligibility for being listed and categorised within the Animal Health Law Framework, will be assessed in separate scientific opinions.

Pathogenicity and innate response to Avibacterium paragallinarum in chickens

Infectious coryza (IC) is an acute infectious upper respiratory disease in chickens. Recently, the prevalence of IC has increased in China. In this study, to clarify the pathogenic mechanism and innate immune response of Avibacterium paragallinarum (A. paragallinarum), an infection experiment with A. paragallinarum was conducted. Our results showed that the whole course of IC was approximately 7 d. The clinical signs score was highest at 3 dpi and decreased from 5 dpi. A large amount of mucus and exudates was found in the infraorbital sinuses and nasal cavity. The A. paragallinarum contents in blood remained the highest, reaching 9.16 × 10⁵ CFU/g at 5 dpi, which indicated that A. paragallinarum could rapidly invade the host, replicate in the blood and cause bacteremia. A. paragallinarum targets the upper respiratory tract. The infiltration of inflammatory cells, macrophages, and heterophilic granulocytes was only observed in the nasal cavity and infraorbital sinus. The Tlr4 and Nod1 pathways were activated and induced proinflammatory responses in chickens after infection with A. paragallinarum. The expression of Il1β and Il6 in the nasal cavity was significantly higher than that in the spleen, and it was consistent with the gross lesions and pathological changes. In particular, the expression of Il6 increased 229.07-fold at 1 dpi in the nasal cavity and increased 3.12-fold in the spleen. The high level of proinflammatory cytokines in the nasal cavity at an early stage of infection may be the main factor related to acute upper respiratory inflammation in chickens. These findings provide a reference for the occurrence and development of diseases mediated by A. paragallinarum.

Antimicrobial sensitivity of Avibacterium paragallinarum isolates from layers in the special region of Yogyakarta, Indonesia

Background and Aim:

Infectious coryza (IC) is an upper respiratory disease of chicken caused by Avibacterium paragallinarum. Its clinical symptoms are swollen face and malodorous sinus exudate. This study was conducted to determine the antimicrobial sensitivity of A. paragallinarum isolates from layers in the Special Region of Yogyakarta, Indonesia.

Materials and Methods:

The samples used in this study were 30 layers that showed IC symptoms. The colony and cell morphology were observed with Gram staining; then, biochemical tests (catalase, oxidase, urease, indole, and motility tests, and carbohydrate fermentation tests using lactose, maltose, mannitol, and sorbitol) were performed to the suspected colony to identify A. paragallinarum. An antibiotic sensitivity test was performed using several antibiotic disks against A. paragallinarum isolates that were cultured on Mueller-Hinton Agar.

Results:

Out of 30 samples, 24 samples (80%) were found positive for A. paragallinarum. All isolates were sensitive to ampicillin (AMP) and amoxicillin (AML) (100%), and chloramphenicol (C) (91.6%). The antibiotics with intermediate sensitivity were enrofloxacin (79.2%), fosfomycin (75%), and ciprofloxacin (54.2%). The isolates were most resistant to erythromycin (100%), followed by tetracycline (87.5%), streptomycin (83.3%), doxycycline and kanamycin (70.8%), and trimethoprim (62.5%).

Conclusion:

Out of the total samples, 24 samples (80%) from layers with IC symptoms were identified biochemically as A. paragallinarum. It was sensitive to AMP, AML, and C.

Efficacy of tetravalent coryza vaccine against the challenge of Avibacterium paragallinarum serovars A and B isolates from Indonesia in chickens

Aim:

Infectious coryza is caused by Avibacterium paragallinarum. In Indonesia, this infection results in a 10%-40% decrease in egg production by laying hens. This study was conducted to determine the effectiveness of tetravalent coryza vaccine contained A. paragallinarum bacterin serovars A, B, C2, and C3; strain A-221, B-Spross, C2-Modesto, and C-3-Akko in layers based on antibody titer and clinical signs using a post-challenge test.

Materials and Methods:

Forty four-week-old Lohmanns strain chickens were used in this study. Forty chickens were divided into four groups for serological and challenge test: Group 1 (unvaccinated and challenged by A. paragallinarum serovar A), Group 2 (unvaccinated and challenged by A. paragallinarum serovar B), Group 3 (vaccinated and challenged by A. paragallinarum serovar A), and Group 4 (vaccinated and challenged by A. paragallinarum serovar B). Vaccination was done using the tetravalent vaccine in oil-emulsion adjuvant contained A. paragallinarum bacterin serovars A, B, C2, and C3; strain A-221, B-Spross, C2-Modesto, and C-3-Akko. Vaccination was performed at day 1 and booster was done at day 14. Blood serum was collected on days 0, 14, and 28 for the hemagglutination-hemagglutination inhibition (HI) test. The challenge test was given at day 29 through intranasal administration using A. paragallinarum serovars A-L2447 and B-L1710 approximately 6×10⁸ CFU/mL. Clinical signs were observed for 14 days post-infection. At the end of the study, chickens were euthanized, and pathological features of the infraorbital sinus, facial skin, and trachea were recorded.

Results:

Data analysis of antibody titers and pathological changes was performed descriptively, while clinical symptom scores were analyzed non-parametrically with the Mann–Whitney U-test using SPSS version 21. At days 14 and 28 post-vaccination, the antibody titer in Group 3 was 5 HI and 20 HI, respectively. However, the antibody titers in Group 4 at 28 days post-vaccination were 0 HI. Clinical observations, the vaccinated groups that were challenged with A. paragallinarum serovars A and B showed clinical symptoms on days 4 and 6 post-infection, namely mild unilateral facial edema and severe bilateral facial edema, respectively. Clinical signs in Groups 3 and 4 were less severe than in Groups 1 and 2 (p<0.05). Pathological examination findings supported clinical observations and serological testing.

Conclusion:

Tetravalent coryza vaccine in chickens has efficacy to protect against the challenge test of A. paragallinarum serovars A and B isolated from Indonesia.

Mortality, disease and associated antimicrobial use in commercial small-scale chicken flocks in the Mekong Delta of Vietnam

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High mortality (2.6 chickens/100 chickens/week) in small-scale Mekong Delta flocks.

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Disease most common in the brooding period; mortality peaks in the 5–10 week period.

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Antimicrobials use (AMU) most common in the early (‘brooding’) period.

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Farmers tend to repeat AMU behavior over consecutive flock cycles.

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AMU was associated with the density of veterinary drug shops.

Raising chickens in small-scale flocks following all-in-all-out management is common in the Mekong Delta of Vietnam. These flocks represent an intermediate category between backyard and intensive (industrial) farming systems. However, little is known about the occurrence and burden of disease and/or mortality in such flocks, and their potential association with antimicrobial usage (AMU). We investigated mortality, disease and weekly antimicrobial use (AMU) in 124 cycles of meat chicken flocks raised in 88 farms in the Mekong Delta of Vietnam (with a median cycle duration of 18 weeks [inter-quartile range IQR 17–20]). We visited each farm 4 times per cycle to review data collected weekly by the farmers on clinical signs, mortality, and AMU. The overall probability of disease and AMU were 0.31 (95% CI 0.29–0.32) and 0.26 (95% CI 0.24–0.28), respectively. The average weekly incidence of mortality was 2.6 (95% CI 2.2–3.0) per 100 birds. Both the probabilities of a flock experiencing disease and mortality, as well as of using antimicrobials decreased with the flock’s age. However, mortality peaked at the 5–10 week period. The only significant explanatory factors associated with presence of disease was the stage of production ≥5 weeks (protective) (OR ≤ 0.51). Factors independently associated with AMU (p < 0.05) were: (1) Number of chickens (log) (OR=1.46), (2) Stage of production ≥5 weeks (OR≤0.67) (protective), (3) Cao Lanh district (OR=2.23), (4) Density of veterinary drug shops at commune level (log) (OR=1.58), and (5) Disease in flocks (OR=1.80). Factors independently associated with overall increased weekly incidence of mortality (p < 0.05) were: (1) High level of education attainment (secondary education or higher) (Hazard rate Ratio [HR]=1.70), (2) number of chickens (log) (HR=1.39), and (3) Stage of production >5 weeks (HR≤2.14). In flocks reporting disease, AMU significantly reduced the incidence of mortality (HR=0.90). These results confirm an exceptionally high mortality in chicken flocks in the area, jeopardizing the profitability and sustainability of these small-scale farming systems. The data also suggest an association between nearby access to antimicrobials and AMU, and a high correlation of AMU over consecutive cycles. The atomized farming landscape of the Mekong Delta, the high incidence of disease and mortality, and the unrestricted and easy access to antimicrobials present major challenges to the implementation of policies aimed at AMU reductions.

Isolation, identification, and serotyping of Avibacterium paragallinarum from quails in Indonesia with typical infectious coryza disease symptoms

Background and Aim

Infectious coryza (IC) or snot is an infectious upper respiratory disease affecting chickens and birds, including quails, and it is caused by Avibacterium paragallinarum. The symptoms of IC are facial swelling, malodorous nasal discharge, and lacrimation. This study aimed to isolate, identify, and serotype the A. paragallinarum of snot in quails and to determine the sensitivity and resistance to several antibiotics.

Materials and Methods

Nine quails from Yogyakarta, Indonesia with typical snot disease symptoms were used in this study. The nasal swab was obtained and directly streaked onto a chocolate agar plate and blood agar plate (BAP), then incubated in 5% CO₂ at 37°C for 24-48 h. Staphylococcus spp. was cross-streaked onto the BAP to show the satellite growth. The observation of the morphology of the suspected colony, Gram staining, and biochemical tests (catalase test, oxidase test, urease test, peptone test, and carbohydrate fermentation such as maltose, mannitol, lactose, and sorbitol) are done to identify the species of bacteria. This research also detects the serovar of A. paragallinarum using hemagglutination inhibition test.The antibiotic sensitivity tests were also performed using several antibiotics against five A. paragallinarum isolates that were cultured on Mueller–Hinton Agar and added with antibiotic discs, then incubated in 5% CO₂ at 37°C for 24–48 h.

Results

Five isolates out of nine suspected isolates (55.5%) were A. paragallinarum. The growth of isolates from quails did not depend on the nicotinamide adenine dinucleotide (NAD) (NAD-independent). Sensitivity test was done using the five identified A. paragallinarum isolates, results showed that they were 100% sensitive to amoxicillin (AMC) and ampicillin (AMP); 100% resistant toward amikacin (AK), erythromycin (E), gentamycin (CN), and tetracycline (TE); 80% resistant toward kanamycin (K) and trimethoprim (W); 60% resistant toward chloramphenicol (C); and 20% toward enrofloxacin (ENR). The antibiotics that have an intermediate sensitivity (in between sensitive and resistant) were ENR and K, 80% and 20%, respectively. Three out of five A. paragallinarum isolates were identified as serovar B of A. paragallinarum using HI test.

Conclusion

Five out of nine isolates (55.5%) from quails with typical IC disease symptoms identified as A. paragallinarum and sensitive toward AMC and AMP. Three out of five A. paragallinarum isolates were identified as serovar B.

Antimicrobial susceptibility of Avibacterium paragallinarum isolates from outbreaks of infectious coryza in Dutch commercial poultry flocks, 2008-2017

The objective of the present study was to determine the in vitro antimicrobial susceptibility of Avibacterium paragallinarum isolates from infectious coryza outbreaks in Dutch commercial poultry, from 2008 till mid-2017. By using a broth microdilution method, minimal inhibitory concentrations (MICs) of 15 antimicrobial agents were assessed, and MIC₅₀ and MIC₉₀ values were determined. Additionally, isolates were subjected to different PCRs for the presence of genes that may confer antimicrobial resistance. Besides field isolates, a set of reference strains, among which the nine Kume strains and one Page serovar strain, were included in the study. For broth microdilution testing a new growth medium, recently developed for susceptibility testing of Haemophilus parasuis, was used. The medium proved to be suitable for broth microdilution susceptibility testing of NAD dependent Av. paragallinarum as well; visible growth was obtained in growth control wells and accepting a deviation of one dilution step, MIC values were reproducible. Results of 44 field isolates originating from 25 outbreaks showed relatively good susceptibility to antimicrobial agents that are recommended for the treatment of infectious coryza in the Netherlands, except for tetracycline; circa 75% of the isolates were characterized by MIC values of tetracycline of ≥16 μg/ml. In almost a quarter of these isolates with high MICs of tetracycline, tet genes were detected. For the remaining isolates with elevated MIC values, the mechanism conferring resistance remains to be studied. Of most agents, low MIC values were determined for the nine Kume and one Page serovar reference strains, as well as negative PCR results for resistance genes, being concordant with agar diffusion results reported for these strains.

Antimicrobial Sensitivity of Avibacterium paragallinarum Isolates from Four Latin American Countries

The antimicrobial sensitivity of 11 reference strains and 66 Avibacterium paragallinarum isolates from four Latin American countries was investigated. All 11 reference strains were sensitive to amoxicillin-clavulanic acid, ampicillin, fosfomycin, gentamicin, kanamycin, neomycin, penicillin, tetracycline, and trimethoprim-sulfamethoxazole. The 11 reference strains were all resistant to lincomycin. All isolates (100%) from Mexico, Panama, and Peru were sensitive to amoxicillin-clavulanic acid, ampicillin, and fosfomycin. The Ecuadorian isolates showed some level of resistance to all 16 agents tested. The Ecuadorian isolates were significantly more sensitive to erythromycin, lincomycin, and streptomycin, and significantly more resistant to gentamicin, kanamycin, penicillin, and tetracycline, than the Mexican isolates. A total of 57.5% (38/66) of tested isolates were multi-drug resistant (MDR), with 16 MDR patterns detected in 88.4% (23/26) of the antimicrobial-resistant isolates from Ecuador, and 8 MDR patterns detected in 42.8% (15/35) of the antimicrobial-resistant isolates from Mexico. In conclusion, the variation in antimicrobial sensitivity patterns between isolates from Ecuador and Mexico emphasizes the importance of active, ongoing monitoring of A. paragallinarum isolates.

Antimicrobial Resistance in Bacterial Poultry Pathogens: A Review

Antimicrobial resistance (AMR) is a global health threat, and antimicrobial usage and AMR in animal production is one of its contributing sources. Poultry is one of the most widespread types of meat consumed worldwide. Poultry flocks are often raised under intensive conditions using large amounts of antimicrobials to prevent and to treat disease, as well as for growth promotion. Antimicrobial resistant poultry pathogens may result in treatment failure, leading to economic losses, but also be a source of resistant bacteria/genes (including zoonotic bacteria) that may represent a risk to human health. Here we reviewed data on AMR in 12 poultry pathogens, including avian pathogenic Escherichia coli (APEC), Salmonella Pullorum/Gallinarum, Pasteurella multocida, Avibacterium paragallinarum, Gallibacterium anatis, Ornitobacterium rhinotracheale (ORT), Bordetella avium, Clostridium perfringens, Mycoplasma spp., Erysipelothrix rhusiopathiae, and Riemerella anatipestifer. A number of studies have demonstrated increases in resistance over time for S. Pullorum/Gallinarum, M. gallisepticum, and G. anatis. Among Enterobacteriaceae, APEC isolates displayed considerably higher levels of AMR compared with S. Pullorum/Gallinarum, with prevalence of resistance over >80% for ampicillin, amoxicillin, tetracycline across studies. Among the Gram-negative, non-Enterobacteriaceae pathogens, ORT had the highest levels of phenotypic resistance with median levels of AMR against co-trimoxazole, enrofloxacin, gentamicin, amoxicillin, and ceftiofur all exceeding 50%. In contrast, levels of resistance among P. multocida isolates were less than 20% for all antimicrobials. The study highlights considerable disparities in methodologies, as well as in criteria for phenotypic antimicrobial susceptibility testing and result interpretation. It is necessary to increase efforts to harmonize testing practices, and to promote free access to data on AMR in order to improve treatment guidelines as well as to monitor the evolution of AMR in poultry bacterial pathogens.

Isolation and characterization of Avibacterium paragallinarum with different nicotinamide adenine dinucleotide requirements

Twenty field isolates of Avibacterium paragallinarum were obtained from chickens in South Korea during 2011-2015. The isolates were identified by a HPG-2 PCR assay specific for A. paragallinarum and by biochemical tests. Growth requirements, Page serovars, carbohydrate fermentation patterns, and antimicrobial susceptibility were also examined. Most isolates (16/20) showed the typical requirement for nicotinamide adenine dinucleotide (NAD) and an enriched CO₂ atmosphere for growth. One isolate needed increased levels of NAD and serum for good growth. Three isolates showed NAD-independent growth on blood agar under aerobic conditions. In terms of carbohydrate fermentation patterns, three biochemical biovars were recognized; these varied with respect to acid production from maltose and D-xylose. The 16 typical NAD-dependent isolates were serovar A while the variants, both NAD-independent isolates and the isolate with increased NAD dependency were non-typeable. All isolates were sensitive to amoxicillin-clavulanic acid, ceftiofur, gentamicin, and spectinomycin. High rates of resistance, including intermediate resistance, to lincomycin (100%), cloxacillin (75%), and erythromycin (70%) were observed. The four variant strains (the three NAD-independent isolates and the isolate showing unusual growth requirements) were more resistant to antibiotics than the typical NAD-dependent strains. The finding of NAD-independent forms of A. paragallinarum extends the known distribution of this form, previously only reported in South Africa, Mexico and Peru. There is clearly a need for increased caution in the diagnosis and, possibly, the control of infectious coryza.

The current epidemiological status of infectious coryza and efficacy of PoulShot Coryza in specific pathogen-free chickens

Infectious coryza (IC) is an infectious disease caused by Avibacterium (Av.) paragallinarum. IC is known to cause economic losses in the poultry industry via decreased egg production in layers. Between 2012 and 2013, Av. paragallinarum was isolated from seven chicken farms by Chungbuk National University. We identified Av. paragallinarum, the causative pathogen of IC by polymerase chain reaction (PCR) and serovar serotype A, by multiplex PCR. Antibiotic sensitivity tests indicated that a few field-isolated strains showed susceptibility to erythromycin, gentamicin, lincomycin, neomycin, oxytetracycline, spectinomycin, and tylosin. A serological survey was conducted to evaluate the number of flocks that were positive for Av. paragallinarum by utilizing a HI test to determine the existence of serovar A. Serological surveys revealed high positivity rates of 86.4% in 2009, 78.9% in 2010, 70.0% in 2011, and 69.6% in 2012. We also challenged specific pathogen-free chickens with isolated domestic strains, ADL121286 and ADL121500, according to the measured efficacy of the commercial IC vaccine, PoulShot Coryza. We confirmed the effectiveness of the vaccine based on relief of clinical signs and a decreased re-isolation rate of ADL121500 strain. Our results indicate IC is currently prevalent in Korea, and that the commercial vaccine is effective at protecting against field strains.

Coinfection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale in Chickens from Peru

The coinfection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale in two outbreaks of infectious coryza from Peru is reported. The diagnosis was confirmed by bacteriologic isolation, PCR testing, and sequencing of the 16S rRNA gene. The susceptibility of the isolates to 12 antimicrobial agents was tested by a disk diffusion method. The isolates were susceptible to amoxicillin/clavulanic acid and florfenicol and were resistant to oxacillin and sulfamethoxazole/trimethoprim. The coinfection of Av. paragallinarum and O. rhinotracheale and the severity of clinical signs were evaluated by experimental infection of specific-pathogen-free chickens. The group inoculated with O. rhinotracheale alone presented minimal clinical signs in 3 of 10 chickens. However, the groups inoculated with both Av. paragallinarum and O. rhinotracheale induced the most-severe clinical signs compared with the group inoculated with Av. paragallinarum alone. In conclusion, coinfections with Av. paragallinarum and O. rhinotracheale may occur, and these outbreaks could be more severe than single infections. Hence, the prevention, control, and diagnosis of Av. paragallinarum with O. rhinotracheale are important in outbreaks of infectious coryza.

Antimicrobial Usage and Antimicrobial Resistance in Animal Production in Southeast Asia: A Review

Southeast Asia is an area of great economic dynamism. In recent years, it has experienced a rapid rise in the levels of animal product production and consumption. The region is considered to be a hotspot for infectious diseases and antimicrobial resistance (AMR). We reviewed English-language peer-reviewed publications related to antimicrobial usage (AMU) and AMR in animal production, as well as antimicrobial residues in meat and fish from 2000 to 2016, in the region. There is a paucity of data from most countries and for most bacterial pathogens. Most of the published work relates to non-typhoidal Salmonella (NTS), Escherichia coli (E. coli), and Campylobacter spp. (mainly from Vietnam and Thailand), Enterococcus spp. (Malaysia), and methicillin-resistant Staphylococcus aureus (MRSA) (Thailand). However, most studies used the disk diffusion method for antimicrobial susceptibility testing; breakpoints were interpreted using Clinical Standard Laboratory Institute (CSLI) guidelines. Statistical models integrating data from publications on AMR in NTS and E. coli studies show a higher overall prevalence of AMR in pig isolates, and an increase in levels of AMR over the years. AMU studies (mostly from Vietnam) indicate very high usage levels of most types of antimicrobials, including beta-lactams, aminoglycosides, macrolides, and quinolones. This review summarizes information about genetic determinants of resistance, most of which are transferrable (mostly plasmids and integrons). The data in this review provide a benchmark to help focus research and policies on AMU and AMR in the region.

Naturally Occurring β-Nicotinamide Adenine Dinucleotide-Independent Avibacterium paragallinarum Isolate in Peru

The β-nicotinamide adenine dinucleotide (NAD) requirement has been considered to be essential for the isolation of the causal agent of infectious coryza, Avibacterium paragallinarum. Nevertheless, NAD-independent reports from South Africa and Mexico dismissed this paradigm. It is now accepted that both NAD-dependent and NAD-independent agents are able to cause infectious coryza and thus belong to the species A. paragallinarum. Here, we report for the first time in Peru a NAD-independent isolate from broiler chickens with typical signs of infectious coryza that have received a trivalent inactivated vaccine against infectious coryza. The isolate was identified based on its morphology, biochemical and serologic tests, and PCR results. Partial 16S rRNA gene sequence analysis confirmed the isolate as A. paragallinarum. There have been no cases of NAD-independent A. paragallinarum isolates reported in South America. Increasing reports around the world highlight not only the need to reconsider the in vitro nutritional requirements of this species for its correct isolation but also the cross-protection conferred by commercial infectious coryza vaccines against NAD-independent isolates.