Study Improves Understanding of E. coli H30 Epidemiology, Persistent Infections Remains Unexplained

Researchers have identified populations more vulnerable to infection with pandemic E. coli strain H30, however improved testing is needed to monitor patients due to the high rate of treatment failure. Antibiotic resistance and weakened immunity only partially explain persistent infection.

E. coli H30 (Sequence Type 131) begins as a subtle, hard-to-detect infection. However, even upon diagnosis and treatment with the right antibiotic, physicians often have trouble eradicating the infection, and complications can set in. The difficulty in subduing the drug-resistant E. coli H30 may also be due to an intrinsic ability that causes persistent, harmful, even deadly infections.

“No other type of E. coli is causing this much widespread damage,” said co-senior author Evgeni Sokurenko, professor, University of Washington (Seattle, WA, USA), “We need to pay as much attention to it as we do to the superbug MRSA, the treatment-resistant staph infection.”

It has been assumed that H30 causes opportunistic infections in the rapidly growing elderly population and others with weakened immune systems. Broad-spectrum antibiotic use may have led to drug-resistance. Additionally, possible presence of as yet-unknown pathogen traits could have contributed to H30’s emergence as a public health problem.

A team of researchers at five USA medical centers—University of Washington, Minneapolis Veterans Affairs Health Care System, University of Minnesota, Seattle Children’s Hospital, and Group Health Cooperative—assessed the nature of H30 infections by analyzing epidemiological and medical data to explore possible associations of H30 with patient characteristics, clinical manifestations, treatment, and how patients fared.

They found that individuals at greater risk for E. coli H30 infection tended to be elderly persons who had been in a healthcare facility, including long-term care residences or hospitals, who had received antibiotics, and who had underlying conditions that weakened their ability to ward off infections.

The researchers also observed that patients who were later shown to have H30 were, at their first physician visit, significantly less likely to be suspected of having an infection and less likely to receive proper antibiotic. Within a month afterward, patients whose initial strain was H30 were more likely to experience severe complication. That is, H30 was strongly associated with ineffective initial therapy and diverse, later-occurring adverse effects.

“It’s possible that H30 might have been hiding from the patients’ natural defenses against infection, thereby impairing the body’s attempt to clear the pathogen during treatment,” said Prof. Sokurenko, “Distinctive properties that perhaps allow H30 to act as a defenses-evading pathogen might also be associated with the delayed complications.”

“H30 might have that dangerous combination of being both highly resistant to antibiotics and highly successful as a stealth pathogen,” added Prof. Sokurenko, “What makes it worse is that can go unnoticed in a patient until it causes significant damage.”

Better methods are needed to anticipate, detect, and diagnose H30 in vulnerable patients who don’t have the usual symptoms of UTI or bloodstream infection. In addition to improved surveillance, Prof. Sokurenko would like rapid tests to become available to determine which antibiotics may or may not work for an individual patient, to help avoid antibiotic-bacteria mismatch and delayed treatment response. “Our findings reinforce the need for a more individualized medicine approach to prescribing antibiotics for E. coli infections,” he said, “Also, even if the infection seems mild, the patient should be monitored carefully so it does not progress unchecked.” Three of the study researchers have patent applications pending for E. coli H30 tests; Prof. Sokurenko is co-founder of ID Genomics.

The study, by Johnson JR et al., was published online March 29, 2016, in the journal Clinical Infectious Diseases.

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