Enumeration and characterization of Aeromonas spp. isolated from milk and some dairy products in Sharkia governorate Egypt

A survey was conducted to determine the prevalence of Aeromonas spp. in 75 random samples [25 each of raw cow's milk, local plain yoghurt and Domiati cheese] collected from different dairy shops, supermarket and street peddlers in Diarb Negm and Zagazig cities Sharkia Governorate, Egypt. Investigations involved proteolytic and lipolytic activities of isolated Aeromonas spp. and the effect of heat- treatment, acidity, pH and Sodium chloride concentration on prevalence of Aeromonas bacteria. Prevalence of Aeromonas spp. was proved in 32, 44 and 20.0% of examined raw cow's milk, local plain yoghurt and Domiati cheese samples with mean count of 9.8 x10[3], 1.4 x10[5] and 6.9 x10[3]/ml, respectively. Identification of confirmed raw cow's milk isolates revealed that A. trota, A. hydrophila, A. janda and A. caviae were the predominant strains with percentages of 40, 25, 25 and 10.0% respectively. While local plain yoghurt isolates could be identified as A. caviae, A. sobria, A. hydrophila, A. trota and A. schubertii with percentages of 36.4, 22.7, 18.2, 13.6 and 9.1% respectively. Meanwhile identification of 10 confirmed Domiati cheese cultures revealed that the predominant strains were A. hydrophila, A. caviae and A. trota with percentages of 30, 50 and 20% respectively. All laboratory pasteurized milk samples revealed no count and there is marked decrease in the count of Aeromonas spp. as the acidity% of the examined raw cow's milk samples increase. While the count decrease when the pH value of the examined local plain yoghurt samples decrease and the NaCl% of the examined Domiati cheese samples increase. Characterization of isolated Aeromonas strains pointed that 50% of A. hydrophila, 60% of A. caviae, 40% of A. sobria, 53.8% of A. Trota, 100% of A. janda and 50% of A. schubertii were psychrotrophic. A. hydrophila exhibited proteolytic and lipolytic activities at the percentage of 41.7 and 16.7% respectively but in case of A. caviae strains the percentages were 46.7% and 20% respectively and with A. trota were 30.8 and 15.4% respectively. 60% of A. sobria and 100% of A. janda and A. schubertii strains showed proteolytic activity only. The public health importance and economic significance of existing microorganisms as well as the suggestive measures for improving the quality of raw milk and dairy products were discussed

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

A total of 221 strains of Aeromonas species isolated in Mexico from clinical (161), environmental (40), and food (20) samples were identified using the automated system bioMérieux-Vitek®. Antisera for serogroups O1 to 044 were tested using the Shimada and Sakazaki scheme. The K1 antigen was examined using as antiserum the O7:K1C of Escherichia coli. Besides, we studied the antimicrobial patterns according to Vitek AutoMicrobic system. Among the 161 clinical strains 60 percent were identified as A. hydrophila, 20.4 percent as A. caviae, and 19.25 percent as A. veronii biovar sobria. Only A. hydrophila and A. veronii biovar sobria were found in food (55 and 90 percent respectively) and environmental sources (45 and 10 percent respectively). Using "O" antisera, only 42.5 percent (94/221) of the strains were serologically identified, 55 percent (121/221) were non-typable, and 2.5 percent (6/221) were rough strains. Twenty-two different serogroups were found, O14, O16, O19, O22, and O34 represented 60 percent of the serotyped strains. More than 50 percent of Aeromonas strain examined (112/221) expressed K1 encapsulating antigen; this characteristic was predominant among Aeromonas strains of clinical origin. Resistance to ampicillin/sulbactam and cephazolin was detected in 100 and 67 percent of Aeromonas strain tested for their susceptibility to antibiotics. In conclusion, antibiotic-resistant Aeromonas species that possess the K1 encapsulating antigen and represent serogroups associated with clinical syndrome in man are not uncommon among Aeromonas strains isolated from clinical, food and environmental sources in Mexico.

Haemolytic activity of aeromonas species isolation in Libya

Twenty seven Aeromonas strains [5A, hydrophila, 8A. sobria and 14A. caviae] isolated from children with diarrhoea and 34 Aeromonas strains [9A. hydrophila. 7A. sobria and 18A. caviae] isolated from children without diarrhoea were tested from haemolysin production. The results obtained showed that haemolysin production using human, horse or sheep erythrocytes was significantly associated with A. hydrophila and A. sobria but not with A. caviae, regardless of whether these strains were isolated from children with or without diarrhoea. Human or horse rather than sheep erythrocytes are recommended for use in the haemolysin assay

Aeromonas sobria in bubaline (water buffalo) abortion: growth requirement, biochemical characters, antibiotic susceptibility, experimental pathogenicity and serology.

A. sobria was isolated unexpectedly on Campylobacter selective medium from abortion specimens of 16 buffaloes. All strains (AS1-AS16) required Campylobacter growth supplement (sodium pyruvate, sodium metabisulphate and ferrous sulphate) and 10% C02 atmosphere on primary isolation. They were unusually sensitive to bile salt and failed to grow on MacConkey's agar. Biochemically, these strains were homogeneous but antibiogram profile and physiological/other characters revealed a moderate heterogeneity. In vitro antibiotic sensitivity pattern showed a number of antibiotics effective whereas only a few (penicillin and co-trimoxazole) ineffective against these strains. It took 9 days for 3 x 10(8) A. sobria organisms/ml in 5 ml quantity to terminate the pregnancy in an experimentally infected buffalo via iv route. Foetal and placental lesions were classical as that of field cases. The infection evoked serum antibody response. Apparently disease-free buffalo sera were devoid of such antibodies.