October 2, 2015 (11:53 am ET) — The “mysterious” infection that sickened 14 patients last week at a hospital in Michigan was caused by a rare bacterial strain called Salmonella Isangi.
Officials of Detroit’s Henry Ford Hospital are not saying much about the outbreak, like how the patients contracted the salmonella, causing speculation to mount about the bug’s source.
Salmonella infections are often traced to contaminated food or water.
Yet, “Salmonella can be transmitted basically by anything that enters your mouth, whether it’s a dirty hand, touching something that has Salmonella and touching your mouth, or food,” an emergency room physician affiliated with Henry Ford Hospital told Food Safety News earlier this week.
The hospital’s statement
“There’s no evidence at this time that the illness is food related,” a statement by Henry Ford Hospital read, adding to the speculation about this outbreak’s other possible causes.
“Salmonella is not typically life-threatening and, in most cases, goes away in less than a week, even if untreated,” the hospital’s statement also noted, adding that no new infected patients have been identified this week.
This “opportunistic” bug can be deadly, however, preying on the frail and weak. Risk factors for infection include hospitalized patients with compromised immune systems and those who are already ill.
“If it’s not food related, where did it come from? Well, that’s the million-dollar question,” asked Detroit’s Local 4 News.
Quality and Safety Services and Case Reviews for Hospitals, Manufacturers, Patients: Click here to read about Dr. Muscarella’s quality and safety services committed to reducing the risk of healthcare-associated infections, including CRE outbreaks linked to contaminated endoscopes and other reusable medical equipment.
Could the strain be CRE?
Salmonella are members of the Enterobacteriaceae family of bacteria about which several of Dr. Muscarella’s recent writings have focused in the context of hospital infections.
Other members of this same family of bacteria include E. coli and Klebsiella.
Those strains that have developed a resistance to antibiotics — most notably, to carbapenems — are a type of deadly ‘superbug’ known as CRE.
In the past, carbapenems (– a type of ‘beta-lactam’ antibiotic so named because of their molecular structures –) have been a “last resort,” or “bug gun,” antibiotic used to treat serious patient infections. Now, some of these infections are untreatable, presenting daunting public health decisions.
At least one report suggested the strain of S. Isangi responsible for Henry Ford’s outbreak last week is multidrug-resistant, which, if confirmed, raises the specter that this hospital’s 14 infections could be a bona fide outbreak of CRE.
Duodenoscopes
Since 2012, several deadly hospital outbreaks of CRE have been linked to contaminated duodenoscopes in Seattle, Pittsburgh, Philadelphia, Charlotte, Los Angeles, and the Chicago suburb of Park Ridge, among other U.S. cities.
None of these outbreaks were caused by Salmonella, however. And no publicized report or finding suggests that Henry Ford’s outbreak last week is due to contaminated medical instrumentation.
According to the Detroit Free Press, however, the Michigan Department of Health and Human Services told the paper that hospital officials are investigating “where (the infected patients) stayed at the hospital, and who their health care workers were while they were there.”
Health officials also told this Detroit newspaper that hospital officials are “looking at what procedures (the 14 infected patients) received.”
The source of the outbreak would likely be easier to determine if most (if not all) of the infected patients underwent one specific type of medical procedure, or were treated in the same room or using the same medical instrument.
Duodenoscopes are a complex type of flexible endoscope used during certain gastrointestinal procedures known as endoscopic retrograde cholangiopancreatography, or ERCP, to diagnose and treat diseases of the bile and pancreatic ducts.
Bronchoscopes
In December 2014, a manufacturer filed a medical device report (or, MDR) with the Food and Drug Administration (FDA) documenting the apparent transmission of CRE by contaminated bronchoscopes, confirming that the transmission of these superbugs is not limited only to instruments used in the GI tract.
According to this filed report, 14 patients tested “positive” for (meaning they were either infected or colonized with) a carbapenem-resistant strain of Klebsiella pneumoniae (i.e., CRE) after having undergone diagnostic bronchoscopy.
Bronchoscopes are a type of flexible endoscope used about 500,000 times a year in the U.S. Their use by lung specialists is crucial to diagnosing and treating a variety of lung-related diseases.
Click here to read my related article, “Contaminated Bronchoscopes Linked in 2014 to A Potential ‘Superbug’ Outbreak: An Under-recognized Risk?” (Bronchoscopes may also be rigid, in design.)
Salmonella enterica
Salmonella can cause enteric fever, septicemia, meningitis and other invasive infections, both in the community and in healthcare facilities.
These bacteria are of either the typhoidal or non-typhoidal type. Typhoid fever, for instance, is caused by S. typhi. Click here to read more about the different types of Salmonella.
The well known Typhoid Mary was the first person identified in the U.S. to be an asymptomatic carrier of typhoid fever, whose common source is contaminated water or food.
While a rare species, however, S. isangi — which infected Henry Ford’s 14 patients and is of the other, non-typhoidal type — has been previously linked to hospital outbreaks, although infrequently and usually in other countries, not the U.S.
Infections of S. Isangi have been reported only four times in the past five years in Michigan, the Michigan Department of Health and Human Services told the Detroit Free Press.
According to the Centers for Disease Control and Prevention (CDC), Salmonella causes as estimated 1 million illnesses in the U.S., with 19,000 hospitalizations and 380 deaths. Most persons infected with the organism develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection.
S. Isangi is a variant, or subtype, of the S. enterica species.
Article by: Lawrence F Muscarella, PhD; posted: October 2, 2015, Rev D.
Lawrence F Muscarella, PhD, is the president of LFM Healthcare Solutions, LLC, a solution-oriented company with the objective to improve healthcare safety through evidence-based consultations. Click here for more details.
Email: Larry@LFM-HCS.com; Twitter: @MuskiePhD