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Clinical and molecular epidemiology of infective endocarditis in intravenous drug users
Pei-Jiuan Chao1, Chih-Ho Hsu, Yung-Ching Liu
1Department of Internal Medicine, Pingtung Christian Hospital, Pingtung, Taiwan, R.O.C.
Background:
Infective endocarditis (IE) in intravenous drug users has been increasing in incidence. The major pathogen used to be methicillin-susceptible Staphylococcus aureus, but resistant isolates have also been increasing. This study aimed to investigate the clinical characteristics of IE in intravenous drug users and to evaluate the molecular patterns of methicillin-resistant S. aureus (MRSA) that cause IE in these drug users.
Methods:
A total of 37 episodes of IE in intravenous drug users hospitalized from 1980 to 2006 at a 1,250-bed teaching hospital in Southern Taiwan were evaluated retrospectively. The genetic relatedness of S. aureus strains was assessed using pulsed-field gel electrophoresis. Polymerase chain reaction was used to detect Panton-Valentine leukocidin (PVL) and staphylococcal gamma-hemolysin (Hlg), and to determine the staphylococcal chromosomal cassette carrying the mecA methicillin-resistant gene (SCCmec) type.
Results:
The patients had a mean +/- standard deviation age of 31.5 +/- 9.25 years, with a male predominance of 76%. Hepatitis C was present in all patients. Methicillin-susceptible S. aureus accounted for 76% of infections, and the most common clinical symptoms were fever (97%) and embolic phenomenon (68%). There were 4 MRSA isolates, 3 of which were SCCmec type III. PVL and Hlg genes were found in 2 and 3 MRSA isolates, respectively. Eighty percent similarity was found among the MRSA isolates by pulsed-field gel electrophoresis.
Conclusion:
Our results suggest that coinfection with hepatitis C was common in intravenous drug users with IE, and that molecular patterns of MRSA isolates had high similarity. SCCmec type III, which is usually hospital-acquired, could have caused the community-associated MRSA endocarditis in our patients.
Insights
Infective endocarditis (IE) in intravenous drug users is rising, with methicillin-resistant Staphylococcus aureus (MRSA) strains showing high genetic similarity. Hepatitis C coinfection was common in these patients.
Area of Science:
- Infectious Diseases
- Microbiology
- Epidemiology
Background:
- Infective endocarditis (IE) incidence is increasing among intravenous drug users (IDUs).
- Methicillin-susceptible Staphylococcus aureus (MSSA) was the primary pathogen, but methicillin-resistant S. aureus (MRSA) is rising.
- Understanding IE clinical characteristics and MRSA molecular patterns in IDUs is crucial.
Purpose of the Study:
- To investigate clinical features of IE in IDUs.
- To evaluate molecular patterns of MRSA causing IE in IDUs.
- To assess the genetic relatedness and virulence factors of MRSA isolates.
Main Methods:
- Retrospective analysis of 37 IE episodes in IDUs from 1980-2006.
- Pulsed-field gel electrophoresis (PFGE) for genetic relatedness of S. aureus.
- Polymerase chain reaction (PCR) to detect Panton-Valentine leukocidin (PVL), staphylococcal gamma-hemolysin (Hlg), and SCCmec types.
Main Results:
- Patients were young (mean age 31.5 years), predominantly male (76%), and all had Hepatitis C.
- MSSA caused 76% of infections; common symptoms included fever and embolic phenomena.
- Four MRSA isolates were identified, three were SCCmec type III, with 80% similarity by PFGE. PVL and Hlg genes were detected in some MRSA isolates.
Conclusions:
- Hepatitis C coinfection is prevalent in IDUs with IE.
- MRSA isolates from IDUs in this cohort exhibited high genetic similarity.
- Community-associated MRSA endocarditis may be linked to hospital-acquired SCCmec type III strains.
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