24 sick in 16 states: Salmonella Typhimurium infections linked to clinical and teaching microbiology laboratories

The U.S. Centers for Disease Control (CDC) and public health officials in several states have identified a multistate outbreak of Salmonella Typhimurium infections linked to various clinical, commercial, and college and university teaching microbiology laboratories.

Public health investigators used the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet, coordinated by CDC, is the national subtyping network of public health and food regulatory agency laboratories. PulseNet performs DNA fingerprinting on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.

Twenty-four people infected with the outbreak strain of Salmonella Typhimurium have been reported from 16 states, including California, Colorado, Florida, Georgia, Iowa, Maine, Michigan, Missouri, North Carolina, New Hampshire, New Jersey, New Mexico, New York, Oklahoma, Texas, and Washington. WGS showed that the strain of Salmonella Typhimurium causing illness in this outbreak is closely related genetically to a strain from an outbreak in 2014 and an outbreak in 2011, both of which were linked to microbiology laboratories. As a result of the 2011 outbreak, several laboratory professionals across the country developed a set of guidelines for handling microorganisms safely in a teaching laboratory.

Among people for whom information was available, illnesses started on dates ranging from March 17, 2017 to June 22, 2017. Ill people ranged in age from less than one year to 57 years, with a median age of 24. Seventy-five percent of ill people were female. Among 21 people with available information, six (29%) were hospitalized. No deaths were reported.

In interviews, ill people answered questions about different exposures in the week before they became ill. Nine (69%) of 13 ill people had laboratory exposures. Ill people in this outbreak reported behaviors while working in the laboratory that could increase the risk of Salmonella infection. These included not wearing gloves or lab coats, not washing hands, and using the same writing utensils and notebooks outside of the laboratory.

This outbreak highlights the potential risk of Salmonella infection associated with working in microbiology laboratories.

All students and staff in clinical and teaching microbiology laboratories should receive laboratory safety training. Either nonpathogenic or attenuated bacterial strains should be used when possible, especially in teaching laboratories. This practice will help reduce the risk of students and their family members becoming ill.

Measuring the old emperor’s clothes: Meta-audit of laboratory ISO accreditation inspections

Accreditation to ISO/IEC 17025 is required for EC official food control and veterinary laboratories by Regulation (EC) No. 882/2004.

emperor’s clothesMeasurements in hospital laboratories and clinics are increasingly accredited to ISO/IEC 15189. Both  of these management standards arose from command and control military standards for factory inspection during World War II. They rely on auditing of compliance and have not been validated internally as assessment bodies require of those they accredit. Neither have they been validated to criteria outside their own ideology such as the Cochrane principles of evidence-based medicine which might establish whether any benefit exceeds their cost.

We undertook a retrospective meta-audit over 14 years of internal and external laboratory audits  that checked compliance with ISO 17025 in a public health laboratory. Most  noncompliances arose solely from clauses in the standard and would not affect users. No effect was likely from 91% of these. Fewer than 1% of noncompliances were likely to have consequences for the validity of results or quality of service. The ISO system of compliance auditing has the performance characteristics of a poor screening test. It adds substantially to costs and generates more noise (false positives) than informative signal.

Ethical use of resources indicates that management standards should not be used unless proven to deliver the efficacy, effectiveness, and value required of modern healthcare interventions.

 Microbiology Open

Ian G. Wilson, Michael Smye, Ian J. C. Wallace


Seek and find: laboratory practices and incidence of non-O157 Shiga toxin–producing Escherichia coli infections

Stigi et al. report in the March, 2012, issue of Emerging Infectious Disease that in a survey of laboratories in Washington State, increased use of Shiga toxin assays correlated with increased reported incidence of non-O157 Shiga toxin–producing Escherichia coli (STEC) infections during 2005–2010.

Despite increased assay use, only half of processed stool specimens underwent Shiga toxin testing during 2010, suggesting substantial underdetection of non-O157 STEC infections.

Strains of Shiga toxin (Stx)–producing Escherichia coli (STEC) are differentiated by the O antigen on their outer membrane and are broadly classified as O157 or non-O157 STEC. The ability to produce Stx is a key virulence trait of STEC. STEC infections in humans often cause a self-limited diarrheal illness but can be complicated by hemorrhagic colitis or hemolytic uremic syndrome.

Unlike other E. coli strains, serogroup O157 isolates do not ferment sorbitol and are readily identified by culture, appearing colorless on sorbitol MacConkey agar. Both O157 and non-O157 STEC can be identified by detecting Stx with nonculture assays that became commercially available in the United States in 1995. The Centers for Disease Control and Prevention (CDC) published formal STEC testing recommendations for clinical laboratories in 2009, advocating that all stool specimens submitted for routine bacterial pathogen testing be simultaneously cultured for O157 STEC and tested with a nonculture assay to detect Stx. Use of this testing protocol ensures timely identification of all STEC infections. Exclusive testing for Stx delays specific identification of O157 STEC and may impede prompt detection of common-source outbreaks.

Non-O157 STEC infection has been a nationally notifiable condition since 2000. Although studies have documented the increased incidence of reported non-O157 STEC infections over the past decade, few have determined the proportion of laboratories that routinely test all submitted stool specimens for Stx and, to our knowledge, no study has quantified STEC testing practices by wwwnc.cdc.gov/eid/article/18/3/11-1358_article.htmproportion of stool specimens processed for bacterial culture. Our objectives, therefore, were to quantify statewide STEC testing practice by proportion of stool specimens processed for bacterial culture and to determine the contribution of enhanced STEC testing practice to increased reported incidence of non-O157 STEC infections.

The complete report is available at: wwwnc.cdc.gov/eid/article/18/3/11-1358_article.htm.

Mobile food-safety labs get FDA up to speed

Elizabeth Weise of USA Today once again goes to the food safety frontlines to report about the mobile testing laboratory being used by the U.S. Food and Drug Administration, this time at the border crossing between Mexico and Nogales, Arizona.

Seventy percent of the fruits and vegetables Americans consume in winter are imported from Mexico, a total of 7 billion pounds, says Allison Moore, communications director for the Nogales-based Fresh Produce Association of the Americas. About half comes through Nogales.

The road that leads to the border begins to fill with trucks carrying fruits, vegetables and manufactured goods at 6:30 a.m. By noon there can be a line of trucks up to 7 miles long snaking through the low desert hills waiting to make the crossing (right ,photo from USA Today).

The lab represents a new era for the agency in keeping the food supply safe, says Michael Chappell, FDA acting associate commissioner for regulatory affairs. It is a tool that can be suited up and rolled out to anyplace in the country facing the danger of contaminated food, whether at the hand of terrorists or Mother Nature.

In the three weeks the trailers were based in Nogales before heading to their next assignment, the FDA estimates that direct contact with the truckers shaved tens of thousands of dollars in testing costs and spoiled produce. The mobile unit also may help repair the agency’s reputation, which has been battered by public frustration with the contamination of such popular foods as peanuts and spinach.

Buyer beware

Some people will do anything for a quick buck. Fake health inspectors in the Greater Toronto Area have been targeting mom and pop food stores in purchasing food safety tests. If managers do not comply, they would be faced with severe health code violations. Now I have heard everything. Health inspectors are required to present valid identification prior to inspecting an establishment. If something does not look right, contact your local health authority.  Food and water tests should also be performed in an accredited laboratory and not on site.


The Toronto Star writes this morning Mom-and-pop food stores and restaurants across the GTA are being scammed by fake health inspectors pushing unnecessary food and water tests, authorities say.


Dozens of convenience store and restaurant owners, most of them new Canadians, have told Peel, Halton and Toronto health departments that they were contacted by a "food and water safety technician" wanting to sell them $30 to $40 safety tests.


The so-called technicians reportedly say the tests are mandatory, and hand out what looks like "old meat plant inspection forms" from the Ontario Ministry of Agriculture, Food and Rural Affairs, said Matt Ruf, Halton Region’s manager of food safety.


Halton and Toronto officials said the people typically identify themselves as representatives of the Canadian Food Safety Institute or the Canadian Food Safety Resource Centre, which the institute founded according to the website www.cfsrc.com.


The CFSI "is not an agency we would deal with," said Rob Colvin, manager of healthy environments for Toronto Public Health.


So far, only a handful of business owners – including two in Toronto – have paid for the tests, officials said.


The cases started emerging first in Peel and Halton in mid-January, then in Toronto about three weeks ago, Colvin said.


Jalal Hadibhai, who owns the Down Under convenience store in Yorkville, said a woman called Monday, saying she would send a technician the next day to perform E.coli tests in the store.


She wanted $39.95 in cash or cheque, he said.


Hadibhai called Toronto Public Health to ask if the tests were legitimate and was told no, he said.


In the end, no one came to the store.


"I would have asked for I.D.," the store owner said. "I would never give them cash."


Sgt. Brian Carr said Halton police are looking for a woman who attempted to sell the tests in a Hasty Market in Oakville yesterday.


She allegedly told the manager that without the tests he could face fines for health code violations.


The woman presented a business card indicating she was from the CFSRC, police said. The organization has addresses in Mississauga and Ottawa.


"There’s no such unit out there," Carr said. Messages left for the CEO of the safety institute were not returned.


A toll-free number listed on both organizations’ websites is out of order.


It’s unclear how many people are involved, but "it seems there’s a whole team of people out there," said Colvin.


Mark Nesbitt, spokesperson for the Ontario Ministry of Health and Long- Term Care, said restaurant and store health inspections lie "entirely in the hands of local public health units."


Any private inspections purchased by business owners would be non- binding and, he added: "Buyer beware."