Antibacterial activities of lactic acid bacteria isolated from selected vegetables grown in nigeria: a preliminary report

Members of lactic acid bacteria (LAB) are known probiotics and have been reported to have antimicrobial properties. Although various researchers have documented the isolation of these bacteria from fruits and vegetables; studies on LAB associated with lettuce; cucumber and cabbage are limited and non-existing in Nigeria. This study was designed to assess lettuce; cucumber and cabbage as potential sources of LAB and investigate the actions of their bacterial cell supernatants (BCS) on some pathogenic bacteria. Using standard microbiological methods; isolated LAB were identified to species level with API 50 CH kits (Biomerieux; France). Cell free supernatants (CFS) from de Man Rogosa Sharpe (MRS) broth cultures of the LAB strains were used to challenge Pseudomonas aeruginosa ATCC 27853; Enterococcus faecalis ATCC 29212; Escherichia coli ATCC 12900 and Proteus penneri ATCC 13315 by agar well diffusion method. The control consisted of the sterile MRS broth subjected to the same growth conditions as LAB broth cultures. A total of four lactic acid bacteria were isolated as follows: Pediococcus pentosaceus 2 from cucumber; Lactobacillus cellobiosus from cabbage; Lactobacillus salivarius and Lactobacillus plantarum 1 from lettuce. Pediococcus pentosaceus 2 and L. salivarius showed inhibitory effects on all the standard strains tested while L. plantarum 1 showed no inhibitory activity against E. faecalis and E. coli. Lactobacillus cellobiosus showed inhibition against all except P. penneri. Although; the molecular characterisation and probiotic potentials of these LAB strains are being investigated in an on-going study; we presumed these vegetables are prospective sources of the bacteria in Nigeria and therefore the need to extensively investigate the vegetables and other related vegetables becomes imperative

Occurrence of Campylobacter species in poultry forms in Lagos area of Nigeria.

Samples of poultry droppings were collected from fifty poultry farms in Lagos area of Nigeria. Campylobacter species were isolated from serially diluted samples using Bolton selective enrichment medium under microaerophilic condition at 42 degrees C. Samples of water, both treated and untreated used in the farms were also analysed in the same manner. Fifteen Campylobacter strains were isolated from the droppings. All the strains were identified using biochemical characteristics differentiating Campylobacter species. They were identified as hippurate positive (C. jejuni) and negative species (C. coli). They were biotype' using the extended scheme described by Lior (1984). Campylobacter coli biotype 'I was the most prevalent (66.66%) followed by C. jejuni biotype 1 (20.00%). The biotype ii of the two species accounted for 6.67% each. The C. jejuni biotype III and IV were not isolated during the study. The preponderance of C. coli indicates that poultry can be a major reservoir for the spread of human campylobacteriosis. Poultry farmers, therefore, must ensure prompt and adequate means of disposal of waste materials as well as maintaining good sanitary conditions.

Epidemiology of shigellosis in Lagos, Nigeria: trends in antimicrobial resistance.

Antimicrobial susceptibility of Shigella spp. and Escherichia coli, isolated from diarrhoeal patients in Lagos, was studied from March 1999 to February 2000. Four hundred fifty-nine isolates were identified as shigellae (62) and E. coli (397). Shigella flexneri, S. dysenteriae, S. boydii, and S. sonnei accounted, respectively, for 51.6%, 17.7%, 17.7%, and 13% of the total number of shigellae isolated. Eleven cases of shigellosis occurred in the age group of 0-9 years, 22 cases in the age group of 10-19 years, and 29 cases in the age group of > or = 20 years. Of the 397 E. coli isolates, 11 were enteropathogenic E. coli (EPEC), and 7 of these strains were isolated with shigellae from stools of patients aged 0-9 year(s) (71.4%) and 10-19 years (28.6%). Over 70% of the Shigella isolates were resistant to two or more drugs, including ampicillin and tetracycline. Twenty-one distinct multidrug resistance patterns were observed in these isolates. During 1990-2000, resistance to ampicillin increased from 70% to 90%, co-trimoxazole from 77% to 85%, chloramphenicol from 71% to 77%, streptomycin from 71% to 79%, and nalidixic acid from 0% to 11.3%. Resistance to tetracycline decreased from 89% to 79% but with MIC50 and MIC90 values outside the susceptible range. While resistance to ciprofloxacin and ofloxacin remained nil with MIC50 and MIC90 values of 0.008 and 0.0016 microgram/mL respectively. The results of this study revealed the endemicity of shigellosis with S. flexneri as the predominant serogroup in Lagos. Children and young adults were at a higher risk of severe shigellosis. The results also suggest that ampicillin, tetracycline, co-trimoxazole, and streptomycin should not be used as the first-line drugs in the treatment of shigellosis. Nalidixic acid should still be selectively used for treatment, while ciprofloxacin and ofloxacin can be ideal alternatives.