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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.

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Gallibacterium anatis has the ability to hemagglutinate rabbit erythrocytes; however, no bacterial component has yet been associated with this function. In the present work, a protein of approximately 65 kDa with hemagglutinating activity for glutaraldehyde-fixed chicken erythrocytes was purified by ion interchange chromatography from G. anatis F149(T) secreted proteins. The protein was recognized by a rabbit polyclonal serum against a hemagglutinin from Avibacterium paragallinarum. The 65 kDa purified protein presented identity with a G. anatis filamentous hemagglutinin by mass spectrometric analysis. As well, the bacterial surface of G. anatis was labeled by immune gold assays using a polyclonal serum against the 65-kDa protein. A similar protein was recognized in four other G. anatis strains by immunoblots using the same antiserum. The protein binds sheep or pig biotinylated fibrinogen, suggesting an interaction with basement membrane eukaryotic cells components, and the protein is present in G. anatis biofilms. Overall, the results suggest that the 65 kDa hemagglutinin is a common antigen and a potential virulence factor in G. anatis.

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The bacterium Avibacterium paragallinarum is the etiologic agent of infectious coryza of chickens. Among the nine Kume serovars currently recognized in this bacterium, serovar B-1 is a common serovar in the Americas. In the current study, serovar B-1 isolates from Ecuador (seven isolates), Mexico (seven isolates) and Panama (two isolates) were genotyped. In addition one Panamanian, one Ecuadorian, and two Mexican isolates were used in a vaccination-challenge trial in which the vaccine was based on the 2671 serovar B-1 reference strain. Genotyping by enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR) resulted in ten distinguishable ERIC patterns for the 16 isolates and the two reference strains of Av. paragallinarum included in the study. No ERIC patterns were shared among isolates of the three different countries. In the vaccination-challenge trial, one isolate from Panama showed a significantly lower virulence than did the three other isolates. In terms of cross-protection, chickens vaccinated with reference strain 2671 and challenged with an Ecuadorian strain showed 40% protection, a significantly lower protection than the homologous protection level. The other three field isolates gave a similar protection level to the homologous challenge.

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The bacterium Avibacterium paragallinarum is the etiologic agent of infectious coryza of chickens. Serovar C-1 has emerged in infectious coryza outbreaks in layer hens of Ecuador and Mexico. In the current study, genotyping and phylogenetic analyses of five Ecuadorian and 10 Mexican isolates of Av. paragallinarum serovar C-1 were performed. All 15 isolates share a unique enterobacterial repetitive intergenic consensus-based-PCR fingerprint and have identical 16S ribosomal RNA and hemagglutinin antigen gene sequences. Results indicate that Ecuadorian and Mexican isolates of serovar C-1 of Av. paragallinarum have a clonal relationship.

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Between 2008 and 2010, 14 isolates of Avibacterium paragallinarum were identified as serovar C-1 in Mexico. All isolates were obtained from commercial laying hens suffering infectious coryza despite a history of vaccination. The enterobacterial repetitive intergenic consensus-based PCR genotyping showed that all isolates had a common pattern. Until recently, serovars A-1, A-2, B-1, and C-2 were the serovars prevalent in Mexico. Serovar C-1 has been identified in Japan and recently in the Americas in Ecuador. Our current study suggests that Av. paragallinarum serovar C-1 is an emerging serovar in Mexico. Our results also indicate that the Mexican isolates of Av. paragallinarum serovar C-1 may have a clonal relationship. Knowledge of the genetic diversity of Av. paragallinarum may be of value in understanding vaccine performance and identifying the best combination to achieve broader protection.

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The protection and level of hemagglutination-inhibition (HI) antibodies conferred in infectious coryza bivalent- and trivalent-immunized chickens against Avibacterium (Haemophilus) paragallinarum field isolates of the prevalent serovars in Mexico (A-1, A-2, B-1, and C-2) were investigated. The bivalent bacterin (A-1 and C-1) conferred significant protection and increased HI antibodies against isolates of serovars A-1, A-2, and C-2, but not against a serovar B-1 isolate. The trivalent bacterin (A-1, B-1, and C-2) conferred protection and increased HI antibodies against all four of the isolates. The results confirmed that in poultry areas where serovar B-1 is prevalent, the inclusion of this serovar in bacterins is needed to confer protection against infectious coryza caused by A. (H.) paragallinarum isolates of serovar B-1.

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Two isolates of Haemophilus paragallinarum were obtained from a layer chicken in Mexico. The isolates were confirmed as H. paragallinarum by polymerase chain reaction and conventional biochemical identification. The isolates were nicotinamide adenine dinucleotide (NAD) independent-growing on blood agar without the need of a nurse colony as well as on a complex medium that lacked both NAD and chicken serum. Both isolates were pathogenic, causing the typical clinical signs of infectious coryza in susceptible chickens. One isolate was Page serovar B/Kume serovar B-1 and the other isolate was Page serovar C/Kume serovar C-2. The isolates were associated with a field outbreak that involved an egg drop of 20% over a 3-wk period and a doubling of weekly mortality (from 0.1% to 0.2%). This is the first report of NAD-independent H. paragallinarum outside South Africa and is the first time that NAD-independent H. paragallinarum of serovar B has been reported.

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As part of the basic characterization of Ornithobacterium rhinotracheale, the minimal inhibitory concentrations of 10 antimicrobial drugs were determined for reference strains and Mexican isolates by a broth microdilution method. For optimal growth of the organisms, a supplemented brain-heart infusion broth was used. The susceptibility of O. rhinotracheale to amoxicillin, enrofloxacin, and oxytetracycline was variable. However, consistent higher minimal inhibitory concentrations values were obtained for gentamicin, fosfomycin, trimethoprim, sulfamethazine, sulfamerazine, sulfaquinoxaline, and sulfachloropyridazine. Obtained results among Mexican isolates indicate a marked antimicrobial drug resistance trend.

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A total of 42 isolates of Haemophilus paragallinarum from Mexico were serotyped by the Kume hemagglutinin scheme. Serovars A-1, A-2, B-1, and C-2 were recognized among 11 (26.2%), 7 (16.6%), 4 (9.5%), and 14 (33.3%) isolates, respectively. A further six isolates (14.3%) showed hemagglutinating activity but could not be classified into any serovar. Commercial vaccines containing Kume serovars A-1, A-2, B-1, and C-2 may provide better protection than those bi- or trivalent infectious coryza vaccines currently used in Mexico.

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Seventeen complicated outbreaks of infectious coryza in layer, broiler-breeder, and broiler flocks were studied. In the layer flock outbreaks, drops in egg production of up to 35% were seen. In the broiler flocks and several of the layer flocks, losses due to persistent mortality and/or culling varied between 2 and 5%. Signs of infectious coryza in both layers and broiler-breeders were typical; in broilers, however, swollen head-like syndrome was seen. Except in one flock, no viral diseases were clinically or serologically detected. Excluding broiler-breeders, birds from most other flocks were serologically positive for Mycoplasma gallisepticum, and some were also positive for M. synoviae. Haemophilus paragallinarum was isolated from all of the outbreaks, but only as a pure culture in three outbreaks. Isolation of H. paragallinarum from sites such as liver, kidney, and particularly tarsal arthritis and ocular globes appears to be reported for the first time. Serovar A was isolated in eight outbreaks, serovar B in six, serovar C in one, and untypable serovars in two. The severity of these infectious coryza outbreaks may have been increased by concurrent salmonellosis, pasteurellosis, and mycoplasmosis, although under certain conditions H. paragallinarum is able to cause septicemia. Ten of the outbreaks occurred in birds vaccinated against infectious coryza; this may be due to the use of vaccines that do not provide protection against the types of H. paragallinarum that affect poultry in the region.

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The biochemical and serological properties of 29 isolates of avian haemophili obtained from chickens in Brazil are described. Twenty-seven of the isolates had the typical biochemical properties of Haemophilus paragallinarum. The two remaining isolates had the typical properties of Pasteurella avium, formerly known as Haemophilus avium. All of the H. paragallinarum isolates were serotyped according to the Page scheme using a hemagglutination-inhibition test. Fourteen of the isolates were serovar A, one was serovar B, 11 were serovar C, and one isolate could not be serotyped. The isolates were also examined using a panel of monoclonal antibodies for Page serovars A (one monoclonal antibody available) and C (three monoclonal antibodies available). As expected, the serovar B isolate failed to react with any monoclonal antibody, whereas the 11 serovar C isolates reacted with all three serovar C monoclonal antibodies but not with the serovar A monoclonal antibody. Only eight of the 14 serovar A isolates reacted with the serovar A monoclonal antibody.

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The biochemical and serological properties of Haemophilus paragallinarum isolates recovered from 11 recent outbreaks of infectious coryza in layer hens and one case of swollen-head syndrome in broilers in Argentina are described. Twenty-four isolates had the typical biochemical properties of H. paragallinarum. All isolates were serotyped according to the Page scheme. Ten of the isolates were serovar A, 11 were serovar B, one was serovar C, and two isolates could not be serotyped. The isolates were also examined using a panel of monoclonal antibodies (MAbs) for Page serovars A (one MAb available) and C (three MAbs available). The serovar B isolates all failed to react with any MAb. The serovar C isolate reacted with all three serovar C MAbs but not with the serovar A MAb. Only six of the 10 serovar A isolates reacted with the serovar A MAb. These results indicate that H. paragallinarum isolates from Argentina are antigenically distinct from those examined in other countries, and it is suggested that coryza vaccines intended for use in Argentina may be more effective if based on local strains.

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