CTX-M-65 Extended-Spectrum ß-Lactamase-Producing Salmonella enterica Serotype Infantis, United States1.

Extended-spectrum ß-lactamases (ESBLs) confer resistance to clinically important third-generation cephalosporins, which are often used to treat invasive salmonellosis. In the United States, ESBLs are rarely found in Salmonella. However, in 2014, the US Food and Drug Administration found blaCTX-M-65 ESBL-producing Salmonella enterica serotype Infantis in retail chicken meat. The isolate had a rare pulsed-field gel electrophoresis pattern. To clarify the sources and potential effects on human health, we examined isolates with this pattern obtained from human surveillance and associated metadata. Using broth microdilution for antimicrobial susceptibility testing and whole-genome sequencing, we characterized the isolates. Of 34 isolates, 29 carried the blaCTX-M-65 gene with <9 additional resistance genes on 1 plasmid. Of 19 patients with travel information available, 12 (63%) reported recent travel to South America. Genetically, isolates from travelers, nontravelers, and retail chicken meat were similar. Expanded surveillance is needed to determine domestic sources and potentially prevent spread of this ESBL-containing plasmid.

Antimicrobial susceptibility testing and successful treatment of hospitalised patients with extensively drug-resistant Campylobacter jejuni infections linked to a pet store puppy outbreak.

OBJECTIVES: Most patients with Campylobacter infection do not require antibiotics; however, they are indicated in severe cases. Clinical breakpoints for many antibiotics are not yet established by the CLSI, making antibiotic selection for resistant infections challenging. During an outbreak of pet store puppy-associated XDR Campylobacter jejuni infections resistant to seven antibiotic classes, several patients required antibiotics. This study aimed to determine MICs of the outbreak strain for various antibiotics and describes the successful treatment of two patients using imipenem/cilastatin, a drug not traditionally used for Campylobacter infections. METHODS: We used whole-genome multilocus sequence typing (wgMLST) to determine the genetic relatedness of Campylobacter isolates collected from two human patients' stool samples with the outbreak strain. We performed extended antimicrobial susceptibility testing on 14 outbreak isolates and 6 control strains to determine MICs for 30 antibiotics (14 classes). RESULTS: Isolates from both patients were highly related to the outbreak strain by wgMLST. MICs indicated resistance of the outbreak strain to most antibiotic classes, except phenicols, glycylcyclines and carbapenems. Due to potential side effects of phenicols and safety issues precluding use of glycylcyclines such as tigecycline when alternatives agents are available, we used carbapenems to treat patients who were severely ill from the outbreak strain infections. CONCLUSION: Stewardship and clinical vigilance are warranted when deciding whether and how to treat patients with suspected C. jejuni diarrhoea with antibiotics. Clinicians should maintain a high index of suspicion for XDR Campylobacter when patients fail to improve and consider the use of carbapenems in such settings.

Epidemiology and Molecular Characteristics of Mycoplasma pneumoniae During an Outbreak of M. pneumoniae-associated Stevens-Johnson Syndrome.

BACKGROUND: An increase in Mycoplasma pneumoniae-associated Stevens-Johnson syndrome (SJS) cases at a Colorado pediatric hospital led to an outbreak investigation. We describe the epidemiologic and molecular characteristics of M. pneumoniae among SJS case-patients and surrounding community members during the outbreak. METHODS: M. pneumoniae polymerase chain reaction-positive respiratory specimens from 5 Colorado hospitals and 4 referral laboratories underwent confirmatory polymerase chain reaction testing; positive specimens then underwent multilocus variable-number tandem-repeat analysis (MLVA) and macrolide resistance testing. Three SJS-M. pneumoniae case-patient households were surveyed using a standardized questionnaire, and nasopharyngeal/oropharyngeal swabs were obtained from all consenting/assenting household contacts. International Classification of Diseases, 9th revision codes were used to identify pneumonia cases among Colorado patients 5-21 years of age from January 2009 to March 2014. RESULTS: Three different M. pneumoniae MLVA types were identified among the 5 SJS case-patients with confirmed infection; MLVA type 3-X-6-2 was seen more commonly in SJS case-patients (60%) than in 69 non-SJS community specimens (29%). Macrolide resistance was identified in 7% of community specimens but not among SJS case-patients. Of 15 household contacts, 5 (33%) were M. pneumoniae positive; all MLVA types were identical to those of the corresponding SJS case-patient, although the specimen from 1 contact was macrolide resistant. Overall pneumonia cases as well as those caused by M. pneumoniae specifically peaked in October 2013, coinciding with the SJS outbreak. CONCLUSIONS: The outbreak of M. pneumoniae-associated SJS may have been associated with a community outbreak of M. pneumoniae; clinicians should be aware of the M. pneumoniae-SJS relationship. Household transmission of M. pneumoniae was common within the households investigated.

Outbreak of Mycoplasma pneumoniae-Associated Stevens-Johnson Syndrome.

BACKGROUND: Stevens-Johnson syndrome (SJS) is an uncommon, sporadic disease and outbreaks are rare. In November 2013, an outbreak of SJS was identified at Children's Hospital Colorado. METHODS: Outbreak cases were children aged 5-21 with a discharge diagnosis of SJS admitted from September 1 to November 30, 2013. Medical charts were reviewed using standardized data collection forms. Respiratory specimens were tested for viruses and Mycoplasma pneumoniae (Mp) by polymerase chain reaction (PCR). We conducted a separate 4-year retrospective case-control study comparing hospitalized SJS cases with and without evidence of Mp infection. RESULTS: During the outbreak, 8 children met SJS criteria. Median age was 11.5 years (range 8-16 years); 5 (63%) were boys and 5 (63%) were Mp-PCR-positive. Of the 5 PCR-positive children, none had preceding medication exposure, and all had radiographic pneumonia. All outbreak Mp isolates were macrolide susceptible. The retrospective case-control analysis showed that Mp-associated SJS episodes (n = 17) were more likely to have pneumonia (odds ratio [OR] 7.5, confidence interval [CI] 1.6­35.1), preceding respiratory symptoms (OR 30.0, CI 3.3­269.4) [corrected] an erythrocyte sedimentation rate ≥35 mg/dL (OR 22.8, CI 2.1-244.9), and ≤3 affected skin sites (OR 4.5, CI 1.2-17.4) than non-Mp-associated SJS episodes (n = 23). CONCLUSIONS: We report the largest outbreak of SJS in children, which was also predominately associated with Mp infection. Mp-associated SJS was associated with a distinct clinical presentation that included less extensive skin disease, an elevated erythrocyte sedimentation rate, and evidence of a preceding respiratory infection.