A comparison of culture and PCR to determine the prevalence of ampicillin-resistant bacteria in the faecal flora of general practice patients.

Of 95 faecal specimens containing bacterial DNA amplified by PCR, 24% contained cultivable bacteria that were resistant to high-level ampicillin. When these samples were examined by PCR using primers to amplify the bla(TEM) gene, the number of positive samples identified increased significantly to 49 (52%). These results indicate that ampicillin resistance is common in the study population. Furthermore, the bla(TEM) gene is more common than indicated by the recovery of resistant bacteria in culture. This points to potential anomalies in the assessment of the prevalence of resistance when relying on recovery of resistant bacteria by culture.