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Enterocolitis caused by methicillin-resistant Staphylococcus aureus: molecular characterization of respiratory and
1Department of Internal Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan. h-wata@net.nagasaki-u.ac.jp
Abstract:
We investigated the mechanism of outbreak of enterocolitis caused by methicillin-resistant Staphylococcus aureus (MRSA). Five epidemiological markers [coagulase type, enterotoxin type, toxic shock syndrome toxin-1 (TSST-1) production, beta-lactamase production and pulsed-field gel electrophoresis (PFGE)] of 45 strains of MRSA isolated simultaneously from the respiratory tract (nasal cavity and/or pharynx and/or sputum) and stool (plus one sample of gastric juice) in 13 patients (8 males and 5 females, mean age, 77.1 years) were compared retrospectively. Forty-four of the 45 isolates of MRSA were positive for enterotoxin C and TSST-1 production, and the remaining isolate was positive for enterotoxin A and negative for TSST-1 production. All isolates were coagulase type II, and 27 showed beta-lactamase production. The patterns of coagulase type, enterotoxin type, TSST-1 and beta-lactamase production of MRSA isolated from the respiratory tract were similar to those of MRSA isolated from the intestine in 12 of 13 patients. Molecular typing by PFGE demonstrated that the pattern of respiratory tract isolates was identical to those of stool isolates in 9 (69.2%), similar in 3 (23.1 %), and different in 1 (7.7%). The data suggested that enterocolitis might be caused by the MRSA colonized in the respiratory tract and incorporated into the digestive tracts. Therefore, we propose that early eradication of MRSA in the respiratory tract is important for protection of patients against the development of enterocolitis, particularly in susceptible patients, e.g., immunocompromised or pre-operated patients with digestive diseases, especially malignant disease.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) causing enterocolitis may originate from respiratory tract colonization. Eradicating MRSA from the respiratory tract is crucial for preventing enterocolitis in vulnerable patients.
Area of Science:
- Infectious Diseases
- Microbiology
- Gastroenterology
Background:
- Enterocolitis outbreaks caused by methicillin-resistant Staphylococcus aureus (MRSA) pose a significant clinical challenge, particularly in elderly and immunocompromised populations.
- Understanding the transmission dynamics and origin of MRSA strains involved in enterocolitis is critical for effective prevention and treatment strategies.
Purpose of the Study:
- To investigate the epidemiological and molecular mechanisms underlying MRSA enterocolitis outbreaks.
- To determine the potential source of MRSA strains causing enterocolitis by comparing isolates from the respiratory and digestive tracts.
Main Methods:
- Retrospective analysis of 45 MRSA strains isolated from respiratory and stool samples of 13 patients with enterocolitis.
- Characterization of MRSA strains using five epidemiological markers: coagulase type, enterotoxin type, toxic shock syndrome toxin-1 (TSST-1) production, beta-lactamase production, and pulsed-field gel electrophoresis (PFGE).
Main Results:
- A high prevalence of enterotoxin C and TSST-1 production was observed in MRSA isolates.
- MRSA isolates from the respiratory tract showed similar epidemiological marker patterns to those from the intestine in most patients (12/13).
- PFGE analysis revealed identical or similar molecular typing patterns between respiratory and stool MRSA isolates in 92.3% of patients, suggesting a common source.
Conclusions:
- The findings suggest that MRSA strains colonizing the respiratory tract can be incorporated into the digestive tract, leading to enterocolitis.
- Early eradication of respiratory tract MRSA colonization is proposed as a key preventive measure against MRSA enterocolitis, especially in susceptible individuals.
- This highlights the importance of screening and decolonization strategies in at-risk patient populations to mitigate MRSA-related gastrointestinal complications.