No abstract

This study further confirms high level resistance to many antimicrobials in different species of Gram-negative bacteria including fluoroquinolones and spread of PMQR genes in Southern Nigeria.

Mycobacterium tuberculosis is the leading cause of death due to infectious disease after Human immunodeficiency virus. There has been an upsurge in the incidence of tuberculosis since 1980s. In order to reverse this trend, there is need to understand the biology of the organism. This can be brought about by studying gene expression at transcriptional level. The success of this hinges on RNA of good quality. In this paper, five methods (hot phenol, sonication with guanidinium thiocyanate (GTC) solution, beadbeating method with Trizol, FastPrep machine with Divolab as detergent and GTC solution, and FastPrep machine with Trizol) of extracting RNA from bacteria were compared to find which of the method would be suitable for mycobacteria. The study found that physical method of lysing bacteria was necessary for extraction of RNA from mycobacteria. FastPrep machine gave the highest yield and also provided the speed necessary for optimum RNA extraction. FastPrep and Trizol as reagent for extraction of RNA was applied to macrophage infected with M. tuberculosis (H37Rv) after removing the macrophage RNA. We were able to demonstrate the expression of dnaK gene in both intracellular and broth grown bacilli. The expression of dnaK gene was found to be downregulated in macrophage compared to broth.

In Nigeria, quinolones and β-lactam antibiotics are widely used as broad-spectrum antibiotics to treat infections caused by various Gram-negative pathogens. The outer membrane is the major permeability barrier limiting target access to quinolones and other drugs in Gram-negative bacteria. This study aimed to identify the role of outer membrane porins (OMPs) and uptake in fluoroquinolone (FQ) and β-lactam drugs accumulation. In total, 134 non-duplicate, Gram-negative bacilli isolates of 13 species from different hospitals were investigated for susceptibility to a panel of antibiotics, including loss of outer membrane porins and measuring active efflux. The minimum inhibitory concentrations (MIC) results showed level of resistance to many antibiotics was extremely high having MIC 90 value of 256 µg/ml or higher for all drugs, most importantly fluorquinolones, ciprofloxacin; sparfloxacin or third generation cephalosporin, ceftazidime; ceftriaxone. SDS-PAGE revealed different outer membrane porin (OMP) profiles on the basis of relative mobility among the strains. The majority of the isolates lack OMPs. The steady-state concentration of drug taken up by the isolates was measured; most of the strains accumulate less bis-benzimidine than the control strain, Salmonella enterica L354. The isolates from University College Hospital, Ibadan accumulate fewer drugs and they are more resistant with high minimum inhibitory concentrations when compared with the rests of the hospitals. Active efflux either singly or in tandem with OMPs alterations could be responsible for the low accumulation of fluoroquinolone and β-lactam antibiotics seen in this study and their increased resistance to both important classes of antibiotics.