Ex-vivo assessment of meningococcal resistance to natural immunity: serum bactericidal assays versus whole- blood assay

1, 2,1 2 (Received 4 Dec, 2008; Accepted 14 Feb, 2009)AbstractBackground and purpose: Literature review indicates that antibiotic resistance of bacteria may be associated with the resistance to host natural immunity. In the previous study we found that: all meningococcal isolates of meningitis cases are less sensitive to typical anti-meningococcal antibiotics. In present study, the association of the above characters was analyzed in an ex-vivo “case-control” study.Materials and methods: A randomized controlled trial compared effect two dietary treatments (low glycemic index & low fat) in 46 adults, ages 18-55 years old, BMI >27,who proceed to motahary clinic in shiraz, Iran. Body weight, BMI, WHR (waist/hip ratio), fast and post-prandial Plasma lipid profile (Triacylglycerol, total Cholesterol, LDL-C, HDL-C concentration) level of obese women measured at the beginning and at the end 6 weeks.Results: The resistance of both groups against selected sera were similar in the ratio 1:2- by SIC and SBC methods. The growth of “test” and “control” groups in the pooled sera were stopped at the ratios 1:512 and 1:1024 respectively. In SBA the population of “test” and “control” groups decreased in parallel to each other. However, the invasive (test) meningococcal strains established slower reduction in WBA.Conclusion: Studies on the correlation between antibiotic resistance of bacteria and the resistance to the natural immunity have ended with different results. According to our experience, it seems that for ex- vivo investigation of natural immunity against meningococci the WBA is more reliable. J Mazand Univ Med Sci 2009; 19(68):48-57 (Persian)