A Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Master of Science in Public Health Research of the Nelson Mandela African Institution of Science and Technology
Plasmids are infectious extra-chromosomal DNA molecules found within bacteria. Their
detection is important for guiding clinical treatment and controlling resistant disease outbreaks in
hospital and community settings. Plasmids were characterized in bacterial isolates recovered
from inpatient retrospective specimens admitted at the Kilimanjaro Christian Medical Centre
(KCMC) from August 2013 to August 2015 in Kilimanjaro, Tanzania; to determine their
prevalence, effects on the risks of antibiotic resistance development and spread. Bacterial isolates
were fully genome sequenced. The risk factors for infections with pathogens resistant to at least
one antibiotic were examined using logistic regression models. Results showed that, 56.2%
(159/283) of bacterial isolates were found to carry plasmids. Twenty-six (86.7%) multiple replicon plasmids and 4 (13.3%) single-replicon plasmids were found to carry both resistance
and virulence genes. There was no statistically significant correlation found between the number
of antibiotic resistance and virulence genes in plasmids (r = -0.14, p > 0.05). Moreover, adjusted
for other factors, lower odds of infection with pathogens resistant to at least one antibiotic for
males (0.16 [95% CI, 0.05 - 0.49]; p= 0.001) was found. However, non-significant difference
odds of carrying resistant pathogens was found between those transferred and non-transferred
patients, and those sought and did not sought medical services. The findings show a relatively
high proportion of plasmid-carrying isolates in the study area, suggesting selection pressure due
to antibiotic use in the hospital. Co-occurrence of antibiotic resistance and virulence genes found
in the studied clinical isolates, affirming that this is a public health concern that needs an
immediate attention.