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Title: Characterisation of antibiotic resistance in Prevotella isolates from cystic fibrosis patients
Author: Sherrard, Laura Jayne
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2013
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Antibiotic treatment of lung infection has been a major contributor to increased life expectancy amongst cystic fibrosis (CF) patients in recent years. Diverse polymicrobial communities including bacteria from the genus, Prevotella, are detected in respiratory samples from CF patients. However, the role of Prevotella in disease progression and the effect of high antibiotic consumption on resistance in this genus are unknown. The primary aim of this study was to determine and compare antimicrobial susceptibility and mechanisms of resistance in Prevotella spp. isolated from CF and non-CF patients. All isolates were susceptible to chloramphenicol, meropenem and piperacillin/tazobactam while metronidazole resistance was rare. In contrast, resistance to amoxicillin, ceftazidime and tetracycline was apparent. CF isolates were more resistant to azithromycin, clindamycin and co-amoxiclav compared to non-CF isolates. Azithromycin resistance was also associated with current prescription of the antibiotic in CF patients. More than 50% of isolates weref3-lactamase positive with an association between β-lactamase production and presence of cfxAlcfxA2. Extended spectrum f3-lactamase (ESf3L) production was detected in 69% of isolates tested and was associated with resistance to ceftazidime and amoxicillin. Isolates positive for ermF and tetQ were more resistant to azithromycin/clindamycin and doxycycline/tetracycline, respectively with ermF detected more commonly in the CF isolates. The nim-type gene was rarely detected but a metronidazole resistant subpopulation with a stable phenotype could be selected for in a nim-positive isolate following exposure to a subinhibitory concentration of the antibiotic in vitro. This study profiles in vitro antibiotic susceptibility of Prevotella spp. in CF and demonstrates that meropenem, piperacillin/tazobactam, chloramphenicol and metronidazole are likely to be the most effective antibiotics if treatment is indicated
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available