Mahmud, Wan Norliyana Wan
(2017)
Detection of macrolide resistant genes of streptococcus pneumoniae isolated from patients in Hospital USM and its clinical outcomes.
Masters thesis, Universiti Sains Malaysia.
Abstract
Streptococcus pneumoniae is one of the leading pathogen causing pneumonia, meningitis,
bacteremia and bacterial otitis media worldwide. It cause more serious disease in young
patients less than 5 years old, elderly aged more than 65 years and in patients with
underlying medical condition such as malignancy, chronic obstructive airway disease,
chronic liver disease, chronic renal disease, diabetes mellitus and smokers. Global increase
in antibiotic resistance in S.pneumoniae remains a serious concern worldwide. In global
multi-country study of antimicrobial susceptibility in S. pneumoniae, revealed that regional
rates of antibiotic resistance were consistently the highest in Asia. The dramatic increase in
in-vitro resistance of S.pneumoniae, particularly beta-lactams and macrolide antibiotic
raised the questions on clinical impact of antimicrobial resistance on clinical outcomes.
The aim of this study is to describe the clinical characteristics and outcome of S.
pneumoniae infection, antibiotic susceptibility pattern, distribution of macrolide-resistance
determinants and its relationship with macrolides susceptibility pattern and clinical
outcomes among patients in Hospital Universiti Sains Malaysia, Kelantan.
Methodology
This is a descriptive cross sectional study conducted in Hospital Universiti Sains Malaysia.
S.pneumoniae, in which non-duplicate isolates were collected from various clinical
specimens from June 2014 to December 2015. Susceptibility to six antibiotics i.e
penicillin, erythromycin, azithromycin, vancomycin, trimetophrim-sulfamethoxazole and
amoxycillin-clavulanic acid were determined using E-test strips (BioMerieux SA, France).
The results were interpreted according to CLSI guidelines. All isolates were subjected to
polymerase chain reaction (PCR) analysis to detect macrolide-resistance determinants.
Patients' clinical data including demographic, clinical diagnosis, risk factors, and outcomes
were obtained from clinical notes.
Results
A total of 113 patients with positive growth of S. pneumoniae from clinical samples were
included in the study. Community-acquired pneumonia is the predominant presentation of
pneumococcal infection. Penicillin resistance rate was 7.1%, with MIC ranging between
0.012 – >32 μg/ml and MIC90 of 1μg/ml. Approximately 26.5% of the isolates resistant to
erythromycin with MIC range of 0.03 – >256 1μg/ml and MIC90 of 32 μg/ml. Among the
erythromycin-resistant isolates, majority were found to have mef(A) gene (50.4%), erm(B)
gene (20%), 16.7% with combination of mef(A) and erm(B) and 13.3% with none of the
two genes. There were no significant association between presence of macrolide resistance
determinants with mortality (p = 0.837) or complications (p > 0.999 for empyema and
cardiac complication; p = 0.135 for subdural abscess)Conclusion
Overall, the isolates showed good susceptibility towards all antibiotics tested except for
azithromycin. The outcome and complications of pneumococcal diseases were not
significantly different between macrolide-resistance than those with macrolide-susceptible
groups and were not affected by the presence of macrolide resistance determinants in the
pneumococcal isolates.
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