Only a quarter of hospital-related Clostridium difficile (C.diff) bugs are traced from symptomatic patients who already have the infection, leaving scientists baffled as to how the superbug spreads.
New findings from a research team at John Radcliffe Hospital, Oxford, contradict existing hospital theories that assume the C.diff bug is spread through contact with infected patients.
Scientists from the study collected stool samples from around 15,000 hospitals and were screened for C.diff toxins.
Of the samples studied, 4.4% came back C.diff positive. Further tests discovered 69 strains of the bacteria but only 23% could be linked to a known infected patient.
Professor Tim Peto, who led the study says: "In this endemic setting with well-implemented infection control measures, up to three quarters of new C.diff infections are not easily explained by conventional assumptions of ward-based transmission from symptomatic patients and so may not be targeted by current interventions."
Professor Peto added that he suspects that instead of encountering C.diff upon entering the hospital, most patients who fell ill with it, carried it with them. Poor health and antibiotic treatment then encourages the bug to grow into the intestines and escalate into an infection.
"You blame the hospital," says Peto. "But that's where you go when you are ill."
Approximately 75% of unexplained transmissions of C.diff could be caused by non-symptomatic carriers, including patients' relatives, staff or through animals or infected food.
Researchers added that there needs to be a better understanding of other routes of infection to reduce the spread of the superbug that affects around 55,000 Brits a year.
The norovirus hit British last year as it suffered double the amount of cases in just two weeks during the peak season, resulting in widespread bed closures in hospitals. Health experts advised that flushing the toilet with the lid down could help prevent the spread of the norovirus.
Symptoms of C.diff infection include diarrhoea and fever.