Methicillin-resistant Staphylococcus aureus proliferation in the rat gut is influenced by gastric acid inhibition and the administration of antibiotics.

The author studied methicillin-resistant Staphylococcus aureus (MRSA) proliferation in the rat gut which was influenced by gastric acid inhibition and the administration of antibiotics. When male Wistar rats were bred by total parenteral nutrition (TPN), and were continuously administered famotidine 4 mg/kg per day, the gastric acidity was observed to decrease to pH 6.4+/-0.1. However, when they were bred by TPN, and histamine 4 mg/kg per hour was continuously administered, the gastric acidity was observed to increase to pH 1.9+/-0.4. MRSA was thus able to cross over to the small intestine only during the famotidine medication. If rats were intravenously administered latamoxef (LMOX) after an oral inoculation of MRSA, then the viable MRSA counts in the stomach, small intestine, and large intestine all decreased on day 4. In contrast, if the gastric acidity decreased and the rats were treated by an oral administration of kanamycin and metronidazole before an oral inoculation of MRSA and thereafter were administered LMOX, then the MRSA count significantly increased. It is thus concluded that a suppression of gastric acid and a great disorder of the intestinal flora is indispensable for the colonization of MRSA into the small intestine, while in vitro the propagation of MRSA requires a continuity of suppression absent in the bacterial flora.