Identification Of Aeromonas Research Articles

Isolation and Identification of Aeromonas spp. from fish and their handlers

Isolation and Identification of Aeromonas spp. from fish and their handlers

Virulence genes contributing to Aeromonas hydrophila pathogenicity in Oreochromis niloticus.

Bacterial diseases are the main cause of high economic loss in aquaculture, particularly gram-negative bacteria. This study was conducted for the isolation and identification of Aeromonas and Pseudomonas spp. from diseased fish. Twenty-two Aeromonas and sixteen Pseudomonas isolates were recovered from diseased Nile tilapia (Oreochromis niloticus) raised in eight earthen ponds in Elhox, Metoubes, Kafrelsheikh, Egypt. The recovered isolates were further identified using PCR as 22 Aeromonas hydrophila, 11 Pseudomonas aeruginosa, and 5 Pseudomonas fluorescens isolates. The 22 A. hydrophila isolates were screened for the presence of four virulence genes. Sixteen of the isolates (72.72%) were positive for the aerolysin gene (aer); 4 (18.18%) harbored the cytotoxic enterotoxin gene (act); and 2 (9.09%) carried the hemolysin A gene (hylA) while the cytotonic heat-stable enterotoxin gene (ast) was absent from all the tested isolates. The pathogenicity test indicated the direct relationship between the mortality percentage and the genotype of the tested A. hydrophila isolates as the mortality rates were 63.3 and 73.3% for isolates with two virulence genes (aer+ & act+, and aer+ and hylA+, respectively), followed by 40, 53.3, and 56.6% for isolates with only one virulence gene (hylA, act, and aer, respectively) and 20% for isolates lacking virulence genes. Based on the sensitivity test, the multi-antibiotic resistance profiles were as follows: 90.9% of the A. hydrophila isolates were sensitive to florfenicol and doxycycline; then 68.18% were susceptible to oxytetracycline, norfloxacin, and ciprofloxacin; and 63.63% were susceptible to sulfamethoxazole-trimethoprim, while only 27.27 and 4.5% were sensitive to erythromycin and cephradine, respectively, and all the isolates were resistant to amoxicillin and ampicillin.

Proteomic characterization and discrimination of Aeromonas species recovered from meat and water samples with a spotlight on the antimicrobial resistance of Aeromonas hydrophila.

Aeromonas is recognized as a human pathogen following ingestion of contaminated food and water. One major problem in Aeromonas identification is that certain species are phenotypically very similar. The antimicrobial resistance is another significant challenge worldwide. We therefore aimed to use mass spectrometry technology for identification and discrimination of Aeromonas species and to screen the antimicrobial resistance of Aeromonas hydrophila (A. hydrophila). A total of 150 chicken meat and water samples were cultured, and then, the isolates were identified biochemically by the Vitek® 2 Compact system. Proteomic identification was performed by MALDI‐TOF MS and confirmed by a microchannel fluidics electrophoresis assay. Principal component analysis (PCA) and single‐peak analysis created by MALDI were also used to discriminate the Aeromonas species. The antimicrobial resistance of the A. hydrophila isolates was determined by Vitek® 2 AST cards. In total, 43 samples were positive for Aeromonas and comprised 22 A. hydrophila, 12 Aeromonas caviae (A. caviae), and 9 Aeromonas sobria (A. sobria) isolates. Thirty‐nine out of 43 (90.69%) Aeromonas isolates were identified by the Vitek® 2 Compact system, whereas 100% of the Aeromonas isolates were correctly identified by MALDI‐TOF MS with a score value ≥2.00. PCA successfully separated A. hydrophila, A. caviae and A. sobria isolates into two groups. Single‐peak analysis revealed four discriminating peaks that separated A. hydrophila from A. caviae and A. sobria isolates. The resistance of A. hydrophila to antibiotics was 95.46% for ampicillin, 50% for cefotaxime, 45.45% for norfloxacin and pefloxacin, 36.36% for ceftazidime and ciprofloxacin, 31.81% for ofloxacin and 27.27% for nalidixic acid and tobramycin. In conclusion, chicken meat and water were tainted with Aeromonas spp., with a high occurrence of A. hydrophila. MALDI‐TOF MS is a powerful technique for characterizing aeromonads at the genus and species levels. Future studies should investigate the resistance of A. hydrophila to various antimicrobial agents.

Evaluation of two different laboratory methods for the identification of Aeromonas spp. in stool sample of patients with diarrhea

Evaluation of two different laboratory methods for the identification of Aeromonas spp. in stool sample of patients with diarrhea

Isolation of Aeromonas spp. from Food Products: Emerging Aeromonas Infections and Their Significance in Public Health.

Aeromonas spp. are opportunistic pathogens causing a broad spectrum of human illnesses like gastroenteritis, chronic diarrhea, wound infections, peritonitis, urinary tract infections, and septicemia. Their ability to grow in foods stored in a refrigerator poses a substantial threat for human consumption. We investigated the prevalence of Aeromonas from commercial food products across Riyadh, Saudi Arabia. A total of 250 samples were randomly collected and processed for the isolation and identification of Aeromonas by morphological and biochemical means and for their identification by PCR. A total of 102 strains of Aeromonas were isolated, including 47% from raw meat samples, 34% from raw fish samples, and 18.6% from milk and dairy products; 56.8% were identified as A. hydrophila and 43.1% as A. sobria. Antibiotic susceptibility tests done revealed 100% sensitivity to chloramphenicol, colistin, ciprofloxacin, and nitrofurantoin. 16S rDNA PCR revealed the presence of the 953 bp fragment in all the strains. The present investigation suggested the occurrences of A. sobria and A. hydrophila in human consumable stored and refrigerated foods.

Caracterização de Aeromonas spp isoladas de amostras de ostras e água por método microbiológico e molecular

Objetivou-se isolar e identificar bactérias do gênero Aeromonas de amostras de ostras e de água, pelos métodos microbiológico e molecular. A identificação do gênero Aeromonas foi realizada pelo método convencional e pela técnica da PCR e a caracterização das espécies foi realizada pela chave de identificação Aerokey II e pela técnica de RFLP-PCR do 16S rDNA. Foram identificadas 59 (98,3%) amostras de ostras e 15 (75%) amostras de água contaminadas por bactérias do gênero Aeromonas. Dos 74 isolados de Aeromonas spp. obtidos pela análise microbiológica, 53 (71,62%), 38 (65,51%) de amostras de ostras e 15 (100%) de amostras de água, confirmaram a caracterização do gênero pela técnica molecular. Quanto a identificação bioquímica das espécies 59,3% (n=35) e 40,6% (n=24) dos isolados de Aeromonassp. obtidos das amostras de ostras foram classificados como A. hydrophila e A. caviae, respectivamente; e para os isolados obtidos das amostras de água, 60% (n=9) foram classificados como A. hydrophila e 40% (n=6) como A. caviae; entretanto, somente a A. hydrophila foi confirmadapelo sequenciamento genético. Quanto a classificação através da RFLP-PCR 16S rDNA, foram obtidos padrões de bandas inespecíficos, impossibilitando a identificação das espécies por esta técnica. O grande número de amostras de ostras contaminadas com Aeromonas spp. e a identificação da A. hydrophila demonstram que este molusco pode oferecer risco à saúde dos consumidores, principalmente por ser consumido in natura e se tratar de um micro-organismo potencialmente patogênico para o ser humano.

Identification ofAeromonas trota(hybridization group 13) by amplification of the aerolysin gene using polymerase chain reaction

Aeromonas trotais recognized as an important enteropathogen, and its haemolysin (aerolysin) is purported to be one of the virulence factors. Rapid detection and identification ofA. trotais important for early and specific diagnosis of the infectious diseases that it causes. Synthetic oligonucleotide primers were used in a polymerase chain reaction (PCR) technique to amplify a species-specific sequence of theaerAgene, which encodes the aerolysin ofA. trota. A DNA fragment of 622 bp was amplified from both lysed cells and isolated DNA fromA. trota. The identity of the amplified 622 bp fragment was confirmed by digestion withBamHI restriction endonuclease, which produced the predicted 557 and 65 bp fragments. The lower limit for detection of theaerAgene by PCR amplification was 10 pg of total DNA or 10–15 cells ml−1. Primer specificity forA. trotawas determined by the PCR assay with cells of 55 strains ofAeromonassppincluding all of the 14 currently recognized DNA hybridization groups. A strain ofAeromonas enteropelogenesthat had been reclassified asA. trotawas also PCR positive. The method described here can be used to detect aerolysin-producingA. trota(hybridization group 13) strains from environmental and clinical samples without the use of selective media or additional biochemical tests.

Prevalence and Characteristics of Aeromonas Species Isolated from Processed Channel Catfish

From August 1994 to May 1995, 238 channel catfish fillets collected from three processing plants in the Mississippi Delta at four time periods were tested for the presence of Aeromonas species. Identification of Aeromonas spp. was accomplished using an automated Vitek bioassay system with gram-negative and nonfermenter cards. Approximately 36.1% were positive for A. hydrophila, 35.7% for A. sobria, and 10.9% for A. caviae. All three Aeromonas spp. were found in all three processing plants, and the incidence of A. hydrophila contamination appeared to be higher in summer than other seasons. Eighty-six percent of the Aeromonas isolates were hemolytic on 5% sheep blood agar plates. Most isolates were susceptible to chloramphenicol, neomycin, streptomycin, and trimethoprim–sulfamethoxazole and resistant to ampicillin and bacitracin. Results suggest that Aeromonas spp. are prevalent in processed channel catfish, and most isolates are hemolytic and resistant to ampicillin and bacitracin.

Isolation and Identification of Aeromonas spp. from Ground Meats in Eastern Canada

Two commercially available media, Ryan's aeromonas medium (RAM) and GSP agar pseudomonas aeromonas selective agar base (GSP) and one laboratory prepared medium, starch ampicillin agar (SAA), were compared for their ability to recover Aeromonas spp. from pure culture, raw ground beef, and spiked autoclaved ground beef samples. In all instances SAA medium proved to be superior for recovery of Aeromonas spp. Selectivity with SAA and GSP was better than with RAM with 100% of typical colonies confirming as Aeromonas spp. The incidence of motile Aeromonas spp. in ground meat samples in Eastern Canada was determined during a 1-year period using SAA as the isolation medium. Aeromonas spp. was found in 4 of 4 ground pork, chicken, turkey, and sausage samples and in 15 of 19 ground beef samples. Two hundred and ten presumptive Aeromonas isolates were characterized biochemically to the species level. Ninety-seven percent of the isolates from pork and 87% from ground beef were identified as Aeromonas hydrophila. Of the isolates from chicken and turkey, 40 and 56% respectively were found to be this latter species. The numbers of Aeromonas sobria and Aeromonas caviae isolated from these products were 30 and 20% for chicken and 8 and 16% for turkey respectively.

Identification ofAeromonas in the routine laboratory

Identification ofAeromonas in the routine laboratory

Observations on the specificities of extracellular antigens of the genera Aeromonas and Serratia.

SUMMARY: Members of the genus Aeromonas produced extracellular toxic antigens which were specific for this group and antisera produced against these antigens could be used to identify these organisms. Strains of A. liquefaciens, A. punctata, A. hydrophila and A. formicans were apparently very closely related; differences which existed between them were not greater than differences found among the strains of A. liquefaciens. Fresh isolates tended to be strongly haemolytic, produced extracellular toxins which were lethal to mice and elicited haemorrhagic lesions upon injection into the skin of rabbit. Old laboratory cultures tended to be much less haemolytic and less toxigenic. A. salmonicida appeared to possess extracellular antigens specific for this species but some strains of A. liquefaciens were found to possess this antigen. Members of the genus Serratia were included in this study since Stevenson (1959) suggested that all Aeromonas strains are non-pigmented forms of Serratia. All strains of Serratia examined, regardless of their classification into species, were homogeneous and reacted with antiserum produced with one strain. Moreover, no cross-reaction was found between the antigens of Aeromonas and Serratia and it appeared unlikely that Aeromonas could be regarded as a non-pigmented member of Serratia. No cross-reaction was found between the extracellular antigens of these two genera and the other members of the families Enterobacteriaceae and Pseudo- monadaceae and antisera produced with these antigens appeared useful in the identification of Aeromonas and Serratia.