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Understanding post-infection irritable bowel syndrome: A large population-based study

Feb. 05, 2021

Gastrointestinal (GI) infections are extremely common in the U.S., with 1 in 6 Americans reporting an episode of foodborne illness annually. Campylobacter is the most common cause of bacterial gastroenteritis in the U.S. Typically, campylobacter infection resolves after initial treatment. But some patients develop a poorly understood condition characterized by chronic GI symptoms of irritable bowel syndrome, known as post-infection irritable bowel syndrome (PI-IBS).

Mayo Clinic researchers seeking to learn more about PI-IBS recently conducted a study to examine the prevalence, risk factors, and symptom type and severity associated with PI-IBS in a large, population-based cohort of patients with laboratory-confirmed campylobacter. The results of this study were published in Clinical Gastroenterology and Hepatology in 2020.

Study methods

The Mayo Clinic research team studied detailed, acute surveillance data obtained from the Minnesota Department of Health that included a large, population-based cohort of patients with laboratory-confirmed campylobacter.

From this cohort, they identified 3,586 patients ages 18 to 80 who experienced new onset of GI symptoms. From 2011 through 2019, the researchers sent Rome III criteria and IBS symptom severity surveys to these individuals six to nine months after campylobacter infection. Using this data, the researchers estimated the prevalence of PI-IBS, and they identified and assessed several potential risk factors using multivariable logistic regression.

Results

According to Madhusudan (Madhu) Grover, M.B.B.S., this study shows that 1 in 5 of those patients diagnosed with campylobacter infection developed PI-IBS. Dr. Grover is a gastroenterologist at Mayo Clinic's campus in Rochester, Minnesota, and the corresponding author for the article in Clinical Gastroenterology and Hepatology.

Among the 1,667 survey respondents, 249 (14.9%) had IBS prior to having campylobacter infection, and the remaining 1,418 did not have preexisting IBS. Within that group of 1,418, 301 (21%) subsequently met the Rome criteria for IBS after infection.

"Our data show that 1 in 5 of those diagnosed with campylobacter infection, the most common cause of bacterial gastroenteritis, may develop chronic GI symptoms of irritable bowel syndrome," says Dr. Grover. "Most of these patients either have alternating diarrhea and constipation or diarrhea alone."

Symptoms among those 301 survey respondents were distributed as follows:

  • 159 (54%) had mixed IBS (IBS-M).
  • 113 (38%) had IBS-diarrhea (IBS-D).
  • 17 (6%) had constipation-predominant IBS (IBS-C).
  • Five (2%) had unsubtyped IBS (IBS-U).

Dr. Grover and colleagues also noted that 65% of these respondents reported moderate to severe symptoms using the IBS-symptom severity scale score (IBS-SSS).

  • The mean IBS-SSS was 218, indicating moderate symptom severity.
  • 28% reported mild symptoms (IBS-SSS of 75-175).
  • 47% reported moderate symptoms (IBS-SSS of 175-300).
  • 18% reported severe symptoms (IBS-SSS > 300).

The researchers also documented shifts in IBS subtype post-infection in respondents with preexisting IBS.

  • 78% diagnosed with IBS-M and 77% with IBS-D before infection retained their subtypes post-infection.
  • 50% diagnosed with IBS-C before infection retained that subtype after infection.
  • 40% diagnosed with IBS-C transitioned to IBS-M after infection.

Overall, among survey respondents with preexisting IBS, 38% had increased frequency of abdominal pain after campylobacter infection. "Patients who had IBS prior to infection may experience worsening of pain and changes in constipation toward diarrhea or mixed bowel habits," says Dr. Grover. "Additionally, some patients may experience just bowel irregularities without pain following such infections."

Potential risk factors

The researchers identified several risk factors that were associated with PI-IBS. Respondents who met the criteria for PI-IBS were more likely to be younger (mean age 43) and female (62%). And they were more likely to experience any of the following during the course of their gastroenteritis episode: significantly longer duration of diarrhea, frequent abdominal cramps, bloody stool or hospitalization. Study data also indicated that fever was inversely associated with PI-IBS.

Dr. Grover and colleagues also identified a number of environmental factors that may play a role in susceptibility for PI-IBS. These include food, especially restaurant dining less than one week before symptom onset; travel, with domestic travelers at higher risk than international travelers; and exposure to animals, especially domestic cats and non-poultry birds. Antibiotic use and exposure patterns were similar between the PI-IBS and control groups.

Conclusions and next steps

Dr. Grover believes that the study findings help paint a clearer picture of a poorly understood condition. This population-based study demonstrated a high risk of PI-IBS development among sporadic campylobacter cases.

"Clinicians need to be aware of this entity so that patients can be properly counseled and treated and avoid unnecessary testing," explains Dr. Grover. "It is important to remember that females, younger individuals, and those who had bloody stools, abdominal cramps and hospitalization during acute enteritis are at a greater risk of developing PI-IBS."

Dr. Grover and colleagues are hopeful that the model presented can help identify patients who are at high risk of PI-IBS development. He acknowledges that additional research is needed to clarify mechanisms of PI-IBS development and why only a subset of patients develops PI-IBS.

"Our laboratory is looking into these mechanisms using animal models, and we are conducting studies assessing changes in gut sensory, motor and barrier function in these patients," says Dr. Grover. "Dedicated longitudinal studies are needed to identify microbial and other novel host risk factors, as well as clinical trials to prevent and treat this chronic complication of infectious gastroenteritis," concludes Dr. Grover.

For more information

Berumen A, et al. Characteristics and risk factors of post-infection irritable bowel syndrome following Campylobacter enteritis. Clinical Gastroenterology and Hepatology. In press.