Faculty of Basic Medical Sciences

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Browsing Faculty of Basic Medical Sciences by Subject "Antibiotic"

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  • Item
    Open Access
    Factors Associated with Pathogenicity and Antibiotic Resistance of Local Strains of Lancefield Groups A, C and G Streptococci
    (University of Lagos, 1989-11-07) Lawal, F.S
    Four thousand, three hundred and ninety five throat, 4,395 nasal and 58 skin lesion swabspecimens were examined bacteriologically out of which 401 (9.12%) were positive for betahaemolytic streptococci (BHS) and 11 (0.25%) for non-haemolytic streptococci (NHS). On the basis of Lancefield group polysaccharide antigens, the isolates were classified into groups A, C, D, G and non-groupable BHS strains. On the basis of bacitracin sensitivity and biochemical analysis, these groups and ungroupable HBS strains were classified into Strept pyogenes Strept. equisimilis, Strept. canis and Strept. milleri. Six members of group A, 68 of group C and 117 of group G BHS isolates were O (SLO), deoxyribonuclease B (DNase B), hyaluronidase, M-associated protein (MAP), serum opacity factor (SOF), proteinase, M,T and R protein antigens. These antigenic components were observed in varying percentages of the isolates: all (100.0%) the six members of group A were positive for SLO and MAP, five (83.3%) for DNase B and hyaluronidase, three (50.0%) for SOF and four (66.6%) for proteinase activity; 41 (60.29%) of group C for SLO and MAP, 52 (76.47%) for DNase B, 56 (82.35%) for hyaluronidase, and nil (0.0%) for both SOF and proteinase while 68 (58.11%) of group G produced SLO, 94 (80.34%) DNase B 56 (47.86%) hyaluronidase, 104 (88.88%) MAP and nil (0.0%) for SOF and proteinase. The ultimately established group C serotype CI and group G serotypes GI - VIII examined for both indigenous and group A - cross - reacting T4 or T25 - antigen showed evidence of these antigens as follows: both serotypes CI and GI showed their indigenous T-antigen and group A cross-reacting T25 and T4 respectively, while serotypes GII - VIII showed indigenous Tantigens only. Varying proportions of those BHS strains (8: 68 for group C and 68: 117 for group G) that produced high ( > 1:80) titres of MAP were studied further. Six members of group C and 19 of group G were ultimately selected as vaccine strains for antisera production in rabbit. Five of the six members of group C and 17 out of 19 of group G successfully produced corresponding type antibodies. Distinct type antisera, one for group C and eight for group Gcorresponding respectively to group C (serotype CI) and group G (serotypes GI - VIII) eventually emerged after absorption with appropriate group C or group G heterologous strains. Other type antisera and their corresponding typeable vaccine strains turned out to be homologous to other group C or group G types. These group C and group G antisera were initially used in parallel with group A type 12 (G 12) and group G strain 51/755 antisera (controls) to screen Lancefield's extracts of 86 group C isolates and 152 group G isolates respectively for evidence of M or R like type antigen. Twelve (13.65%) of the 86 group C and 75 (50.33) of 149 group G isolates could be M-serotyped while none (0.0) showed evidence of R-like antigen/antibody activity. The remaining 76 (86.36%) group C and 74 (49.66%) group G isolates could not be serotyped with the available antisera. Twenty (Co5T'S'). The three patterns occurred in varying percentages of 63.48 (353/556), 33.27 (185/556) and 3.25 (18/556) respectively. Representative strains of the three antibiotic susceptibility patterns, Co5 S' T', Co5 S' T5, and Co' S' T' were observed further to show varying (80 - 0.62 ug/ml) rages of minimum inhibitory concentrations (MIC) of chloramphenicol co-trimoxazole, erythromycin, penicillin G, streptomycin and tetracycline for the three antibiotic - susceptibility patterns, which in the case of chloraphenicol, co-trimoxazole, erythromycin and penicillin G correlated with in vitro susceptibility and in the case of streptomycin and tetracycline correlated with in vitro resistance of the BHS isolates tested against the six antibiotics. The three representative patterns were further screened for evidence of antibiotic - resistance factors, plasmid deoxyribonucleic acid and beta-lactamase for which none of the isolates was positive.
  • Item
    Open Access
    Immunological Studies on Strains of Campylobacter Jejuni Isolated in Lagos, Nigeria.
    (University of Lagos, 1989-06-12) Obi, L.C
    Microbiology is a dynamic discipline, the taxonomy of some species is rapidly changing. Organisms which were not known to previously cause infection of some opportunistic pathogens are now incriminated in disease causation. Until recently, the unequivocal bacterial agents of diarrhoea in our environment and even world wide were Salmonella spp., Shigella spp. and Vibrio cholera. However more recent bacterial agents of diarrhoea or gastroenteritis include Yersinia enterocolitica, Clostridium difficle, Liseria monocytogenes and Campylobacter jejuni. In Nigeria, cases of diarrhoea due to Campylobacter jejuni may exceed the frequency of salmonelle and Shigella combined (Coker and Dosunmu-Ogunbi, 1983). In Nigeria, studies on Campylobacter are still at its infacy. Until date, reports on Campylobacter jejuni have been on pathogenicity assessment, biotype and serogroups distribution, plasmid profiles, Campylobacter as agent of gestroenterities and anti-microbial agents. Presently, detailed immunological studies or reports on Campylobacter jejuni are lacking in Nigeria. For example, production of antisera against the organism has not been attempted. Experimental studies involving diagnostic or protective effects of anti-Campylobacter antibody in line with recent developments in Imunology are not available. The levels of antibodies among patients with diarrhoes due to Campylobacter jejuni and asymptomatic individuals including the bactericidal power of normal human serum against the organism have also not been determined. A simple presumptive test for the organism in our environment is still non-existent. In light of all these, should we remain complacent and continue to depend on reports from developed countries? As microbiologists are we not aware that strains of particular organism vary from country to country? Is it then very appropriate to continue to import antisera for the diagnosis of our local strains of Campylobacter jejuni? As indigenous scientists, do we have any justification in believing that for example, immunological studies on a particular organism carried out abroad must bear relevance to our local organism? This thesis is an attempt to document immunological studies on our local strains of Campylobacter jejuni.