Enterotoxic meticillin-resistant Staphylococcus aureus: prevention and control

Abstract number: O511

Yoshida Y., Sumiyama Y., Kusachi S., Arima Y., Tanaka H., Sato J., Saito T., Nagao J., Saida Y., Watanabe M.

Objectives: Superantigenic exotoxins such as toxic shock toxin 1 appear to be major virulence factors in hospital meticillin-resistant Staphylococcus aureus clones (HA-MRSA) in Japan, and staphylococcal enterotoxin may be involved in the septic shock and MRSA enterocolitis. To control enterotoxic MRSA infections, we examined the homeostasis of intestinal bacteria.


1MRSA proliferation according to the control of intestinal bacteria:

AFour GAM broth tubes were prepared, and tubes were inoculated 105 cfu/ml of viable MRSA328GTS, Escherichia coli ATCC25922, Enterococcus faecalis ATCC29212, and Bacteroides fragilis GM7000, and cultivated for 24 hours (= independent cultivation). Next, a GAM broth tube was prepared, and inoculated mixed up with above 4 strains (= mixed cultivation).

BAfter managed under eight days of total parental nutrition (TPN) and continuous administration of antacid, viable bacterial counts in large bowel of male Wistar rats (body weight 250g) were counted after an inoculation of 109 cfu/rat MRSA238 solution by gastric tube on day four.

2Control of intestinal flora and MRSA proliferation:

AViable MRSA counts were compared among mixed cultivation tubes added moxalactam (MOX), metronidazole (MTN), and MOX+MTN.

B(1) Chemoprophylaxis (CP) group: rats were inoculated MRSA solution after three days of oral antibiotic, kanamycin and MTN. (2) MOX group: rats were administered MOX for three days after an inoculation of MRSA solution. (3) Probiotics group: Probiotics, bio-three(R) 1g/day, were orally administered every day after inoculation of MRSA solution.


1(A) Independent cultivations were at 11, 9, 9, and 10, and mixed cultivations were at 5.2, 7.6, 7.5, 9.5 (logCFU/ml).
(B) Viable bacterial counts of the S. aureus in TPN was 3.6, and the MRSA in TPN+MRSA was 3.0 (not significant), and was able to consider the MRSA multiplication control by intestinal bacteria.

2(A) the counts of MRSA were 3.7, 4.5, and 7.5, respectively. MRSA were proliferated under suppression of two or more major intestinal bacteria.
(B) The counts of MRSA were elevated to 6.8 in CP+MRSA+MOX, and diarrhoea was observed. The counts were decreased to 1.8 after treatment by probiotics, and frequency of the diarrhoea was decreased from 60% to 25%.

Conclusion: Disturbances on intestinal flora were suggested to be a major cause of enterotoxic MRSA infections, and a control of intestinal flora will be important to prevent enterotoxic MRSA infections.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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