BACKGROUND: In 2018, CDC and the Vermont Department of Health investigated an outbreak of multidrug-resistant Shigella sonnei infections in a retirement community that offered a continuum of care from independent living through skilled nursing care. The investigation identified 24 culture-confirmed cases. Isolates were resistant to trimethoprim-sulfamethoxazole, ampicillin, and ceftriaxone, and had decreased susceptibility to azithromycin and ciprofloxacin. METHODS: To evaluate clinical and microbiologic response, we reviewed inpatient and outpatient medical records for treatment outcomes among the 24 patients with culture-confirmed S. sonnei infection. We defined clinical failure as diarrhea (≥3 loose stools per day) for ≥1 day after treatment finished, and microbiologic failure as a stool culture that yielded S. sonnei after treatment finished. We used broth microdilution to perform antimicrobial susceptibility testing, and whole genome sequencing to identify resistance mechanisms. RESULTS: Isolates contained macrolide resistance genes mph(A) and erm(B) and had azithromycin minimum inhibitory concentrations above the Clinical and Laboratory Standards Institute epidemiological cutoff value of ≤16 µg/mL. Among 24 patients with culture-confirmed Shigella infection, four were treated with azithromycin; all had clinical treatment failure and two also had microbiologic treatment failure. Isolates were susceptible to ciprofloxacin but contained a gyrA mutation; two patients failed treatment with ciprofloxacin. CONCLUSIONS: These azithromycin treatment failures demonstrate the importance of clinical breakpoints to aid clinicians in identifying alternative treatment options for resistant strains. Additionally, these treatment failures highlight a need for comprehensive susceptibility testing and systematic outcome studies, particularly given the emergence of multidrug-resistant Shigella among an expanding range of patient populations.

A large outbreak of extensively drug-resistant (XDR) Salmonella enterica serotype Typhi infections is ongoing in Pakistan, predominantly in Sindh Province. Here, we report the sequencing and characterization of five XDR Salmonella Typhi isolates from the Punjab province of Pakistan that are closely related to the outbreak strain and carry the same IncY plasmid.

BACKGROUND: Produce-associated outbreaks of Shiga toxin-producing Escherichia coli (STEC) were first identified in 1991. In April 2018, New Jersey and Pennsylvania officials reported a cluster of STEC O157 infections associated with multiple locations of a restaurant chain. CDC queried PulseNet, the national laboratory network for foodborne disease surveillance, for additional cases and began a national investigation. METHODS: A case was defined as an infection between March 13 and August 22, 2018 with one of the 22 identified outbreak-associated E. coli O157:H7 or E. coli O61 pulsed-field gel electrophoresis pattern combinations, or with a strain STEC O157 that was closely related to the main outbreak strain by whole genome sequencing. We conducted epidemiologic and traceback investigations to identify illness sub-clusters and common sources. An FDA-led environmental assessment, which tested water, soil, manure, compost, and scat samples, was conducted to evaluate potential sources of STEC contamination. RESULTS: We identified 240 case-patients from 37 states; 104 were hospitalized, 28 developed hemolytic uremic syndrome, and five died. Of 179 people who were interviewed, 152 (85%) reported consuming romaine lettuce in the week before illness onset. Twenty sub-clusters were identified. Product traceback from sub-cluster restaurants identified numerous romaine lettuce distributors and growers; all lettuce originated from the Yuma growing region. Water samples collected from an irrigation canal in the region yielded the outbreak strain of STEC O157. CONCLUSION: We report on the largest multistate leafy green-linked STEC O157 outbreak in several decades. The investigation highlights the complexities associated with investigating outbreaks involving widespread environmental contamination.

Campylobacter is a leading cause of foodborne illness in the United States, causing an estimated 1.3 million illnesses annually.

On June 9, 2016, the Mississippi Poison Control Center and the Mississippi State Department of Health (MSDH) notified CDC of five suspected cases of botulism, a potentially fatal neuroparalytic illness (1), in inmates at a medium-security federal correctional institution (prison A). By June 10, a total of 13 inmates were hospitalized, including 12 in Mississippi and one in Oklahoma (the inmate in Oklahoma had been transferred there after his exposure for reasons unrelated to his illness). MSDH, Oklahoma State Department of Health, Bureau of Prisons, and CDC conducted an investigation to identify the source and scope of the outbreak, and to develop recommendations. | Prison A staff members suspected that an alcoholic beverage, illicitly made by inmates and known as “hooch” or “pruno,” was the source of the outbreak. Among 33 inmates who reported consuming hooch during June 1–19, 2016, a total of 31 (94%) had signs or symptoms suggesting botulism. The median interval from first exposure to symptom onset was 3 days (range = 0–11 days) (Figure). Cases were categorized using modified Council of State and Territorial Epidemiologists definitions. A confirmed case was defined as an illness in an inmate consistent with botulism that began on or after June 1, with botulinum toxin type A detected in a serum or stool specimen or Clostridium botulinum cultured from a stool specimen; a probable case was defined as an illness in an inmate with signs or symptoms of any cranial nerve palsy and extremity weakness that began on or after June 1; and a suspected case was an illness in an inmate with signs or symptoms of any cranial nerve palsy without extremity weakness that began on or after June 1.

The mcr-1 gene confers resistance to the polymyxins, including the antibiotic colistin, a medication of last resort for multidrug-resistant infections. The mcr-1 gene was first reported in 2015 in food, animal, and patient isolates from China and is notable for being the first plasmid-mediated colistin resistance mechanism to be identified. Plasmids can be transferred between bacteria, potentially spreading the resistance gene to other bacterial species. Since its discovery, the mcr-1 gene has been reported from Africa, Asia, Europe, South America, and North America, including the United States, where it has been identified in Escherichia coli isolated from three patients and from two intestinal samples from pigs. In July 2016, the Pathogen Detection System at the National Center for Biotechnology Information (Bethesda, Maryland) identified mcr-1 in the whole genome sequence of an E. coli isolate from a Connecticut patient; this is the fourth isolate from a U.S. patient to contain the mcr-1 gene.

During October 2013-June 2014, approximately 54,000 unaccompanied children, mostly from the Central American countries of El Salvador, Guatemala, and Honduras, were identified attempting entry into the United States from Mexico, exceeding numbers reported in previous years. Once identified in the United States, U.S. Customs and Border Protection, an agency of the U.S. Department of Homeland Security, processes the unaccompanied children and transfers them to the Office of Refugee Resettlement (ORR), an office of the Administration for Children and Families, U.S. Department of Health and Human Services. ORR cares for the children in shelters until they can be released to a sponsor, typically a parent or relative, who can care for the child while their immigration case is processed. In June 2014, in response to the increased number of unaccompanied children, U.S. Customs and Border Protection expanded operations to accommodate children at a processing center in Nogales, Arizona. ORR, together with the U.S. Department of Defense, opened additional large temporary shelters for the children at Lackland Air Force Base, Texas; U.S. Army Garrison Ft. Sill, Oklahoma; and Naval Base Ventura County, California.