1252. A Challenging Burkholderia Outbreak Investigation Across Multiple Units at an Academic Medical Center From June 2017 to February 2018

Background Most outbreak investigations involve short-term, geographically localized clusters. However, some organisms can form environmental reservoirs leading to more prolonged, widespread outbreaks. We describe a prolonged outbreak of Burkholderia at our institution. Methods An epidemiological investigation was conducted. Burkholderia isolates were genotyped using pulsed-field gel electrophoresis (PFGE) and recA gene sequencing. Initial isolates were sent to a national reference laboratory for multilocus sequence typing (MLST). Results 32 patients on 12 units (see figure) had ≥1 positive culture for Burkholderia from June 2017 to February 2018. 21 had B. cenocepacia (PFGE pattern A, recA allele 365) and 11 had B. cepacia (PFGE pattern C, recA allele 53). MLST revealed that isolates with recA allele 365 were unique compared with previously identified B. cenocepacia strains. Of 32 patients, 28 (88%) had positive respiratory cultures. Of 32 patients, 3 (9%) had bacteremia. Thirty-day mortality was 4/29 (14%). A case–control study did not reveal a common point source. All surveillance cultures from asymptomatic patients were negative (n = 53). Two of nine sink drains in rooms of cases were positive for an unrelated strain of B. cepacia. Other environmental cultures were negative for Burkholderia (n = 49). Cases continued despite routine interventions (see figure), with some incident cases detected long after potential exposures. Ventilator/respiratory equipment (V/RE) cleaning was investigated. Multiple V/RE interventions were implemented: (1) ensuring a sterilization process for ventilator temperature probes (used in heated humidification) was occurring; (2) using disposable manometers on contact isolation patients; (3) reinforcing ventilator cleaning, including those in radiology suites after use. Conclusion No definitive source of the outbreak was found. New cases continued after reinforcement of basic infection control practices, but subsided after focused attention on V/RE cleaning practices. Control of this outbreak was challenging due to the complexity of a prolonged “latency period” for Burkholderia, difficulty identifying reservoirs, and multiple possible modes of transmission, especially for organisms like Burkholderia that can persist on environmental surfaces and equipment. Disclosures All authors: No reported disclosures.

DiverseEscherichia colilineages, from domestic animals and humans in a household, carry colistin resistance genemcr-1in Ecuador

The aim of this study was to investigate the presence ofEscherichia colicarryingmcr-1gene in domestic animals close to a child who suffered a peritoneal infection by amcr-1positiveE. coli. Rectal or cloacal swabs and fecal samples from domestic animals were plated on selective media to isolate colistin-resistantE. coliand isolates were submitted to detection ofmcr-1gene, pulsed field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), replicon typing and S1-PFGE. Fourmcr-1positiveE. coliisolates (from chicken, turkey and dog) were recovered. No shared PFGE pattern or MLST sequence type were observed among isolates. A 60Kb IncI1γmcr-1-carrying plasmid was detected in all isolates. Our results suggest thatmcr-1gene was horizontally disseminated amongst different lineages ofE. colifrom domestic animals in the child’s household.ImportanceHorizontally transferable colistin resistance (mcr-1 gene) is thought to have originated in domestic animals and transferred to humans through meat and dairy products. In the present report we show evidence that themcr-1 gene could be transferred to differentE. colistrains colonizing different hosts (humans and pets) in the same household.

Detection of mcr-1 colistin resistance gene in polyclonal Escherichia coli isolates in Barcelona, Spain, 2012 to 2015

Colistin resistance was detected in 53 of 10,011 Escherichia coli (0.5%) by prospective phenotypic testing of consecutive clinical isolates in a single hospital in Barcelona, Spain (2012–15). The mcr-1 gene was retrospectively identified by PCR and sequencing in 15 of 50 available isolates. Each isolate had a unique PFGE pattern except for two. This clonal diversity supports the hypothesis of horizontal dissemination of the mcr-1 gene in the local study population.

Characterization ofClostridium difficileStrains in British Columbia, Canada: A Shift from NAP1 Majority (2008) to Novel Strain Types (2013) in One Region

Background.Clostridium difficileis a major cause of gastrointestinal illness. Epidemic NAP1 strains contain toxins A and B, a deletion in repressortcdC, and a binary toxin.Objectives. To determine the molecular epidemiology ofC. difficilein British Columbia and compare between two time points in one region.Methods.C. difficileisolates from hospital and community laboratories (2008) and one Island Health hospital laboratory (2013) were characterized by pulsed-field gel electrophoresis, PCR-ribotyping, toxin possession,tcdCgenotype, and antimicrobial susceptibility.Results. In 2008, 42.7% of isolates had NAP1 designation. Hospital-collected isolates were associated with older patients and more NAP1 types. Unlike other isolates, most NAP1 isolates possessed binary toxin and a 19 bp loss intcdC. All isolates were susceptible to metronidazole and vancomycin. A 2013 follow-up revealed a 28.9% decrease in NAP1 isolates and 20.0% increase in isolates without NAP designation in one region. Then, community-associated cases were seen in younger patients, while NAP types were evenly distributed. Isolates without NAP designation did not cluster with a PFGE pattern or ribotype.Conclusions. Evaluation ofC. difficileinfections within British Columbia revealed demographic associations, epidemiological shifts, and characteristics of strain types. Continuous surveillance ofC. difficilewill enable detection of emerging strains.

Ongoing outbreak of invasive listeriosis, Germany, 2012 to 2015

Listeriosis patient isolates in Germany have shown a new identical pulsed-field gel electrophoresis (PFGE) pattern since 2012 (n = 66). Almost all isolates (Listeria monocytogenes serotype 1/2a) belonged to cases living in southern Germany, indicating an outbreak with a so far unknown source. Case numbers in 2015 are high (n = 28). No outbreak cases outside Germany have been reported. Next generation sequencing revealed the unique cluster type CT1248 and confirmed the outbreak. Investigations into the source are ongoing.

Molecular typing of Shigella sonnei isolates circulating in Nanjing, China, 2007–2011

Introduction: Shigellosis is a major public health concern worldwide. This study intended to assess the baseline genotyping data among local Shigella sonnei strains spanning over five years. Methodology: Fifty non-repeat clinical strains of S. sonnei isolated from stools of patients in different hospitals in Nanjing, China, were studied. Three subtyping tools, pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), and multi-locus variable-number tandem-repeat (VNTR) analysis (MLVA), were used for routinely subtyping local S. sonnei. Results: DNA sequencing only identified two sequence types (STs) among the 50 isolates in the MLST profiles, whereas PFGE and MLVA both showed suitable discriminatory power and yielded 19 and 30 different patterns, respectively. The major PFGE pattern comprised 21 strains isolated from different years. A total of four complexes were identified by MLVA, with the isolates differing by a single locus (single-locus variants). Conclusions: The S. sonnei strains circulating in Nanjing, China, in 2007–2011 originated from different clones with a degree of diversity. Most of the clones were closely related to each other. Overall, the strains were distinguishable by PFGE and MLVA. MLVA based on eight selected VNTR loci represented a more favorable degree of discrimination than did PFGE and may be a reliable complement for PFGE for routine subtyping of S. sonnei. The problems of MLST in subtyping regarding S. sonnei were also demonstrated.

Arcobacter butzleri in Sheep Ricotta Cheese at Retail and Related Sources of Contamination in an Industrial Dairy Plant

ABSTRACTThis study aimed to evaluateArcobacterspecies contamination of industrial sheep ricotta cheese purchased at retail and to establish if the dairy plant environment may represent a source of contamination. A total of 32 sheep ricotta cheeses (1.5 kg/pack) packed in a modified atmosphere were purchased at retail, and 30 samples were collected in two sampling sessions performed in the cheese factory from surfaces in contact with food and from surfaces not in contact with food. Seven out of 32 samples (21.9%) of ricotta cheese collected at retail tested positive forArcobacter butzleriat cultural examination; all positive samples were collected during the same sampling and belonged to the same batch. Ten surface samples (33.3%) collected in the dairy plant were positive forA. butzleri. Cluster analysis identified 32 pulsed-field gel electrophoresis (PFGE) patterns. The same PFGE pattern was isolated from more than one ricotta cheese sample, indicating a common source of contamination, while more PFGE patterns could be isolated in single samples, indicating different sources of contamination. The results of the environmental sampling showed thatA. butzlerimay be commonly isolated from the dairy processing plant investigated and may survive over time, as confirmed by the isolation of the same PFGE pattern in different industrial plant surface samples. Floor contamination may represent a source ofA. butzlerispread to different areas of the dairy plant, as demonstrated by isolation of the same PFGE pattern in different production areas. Isolation of the same PFGE pattern from surface samples in the dairy plant and from ricotta cheese purchased at retail showed that plant surfaces may represent a source ofA. butzleripostprocessing contamination in cheeses produced in industrial dairy plants.

Outbreak of PER-1 and diversity of β-lactamases among ceftazidime-resistant Pseudomonas aeruginosa clinical isolates

A growing number of β-lactamases have been reported in Pseudomonas aeruginosa clinical isolates. The aim of this study was to investigate the diversity of β-lactamases in the collection of 51 ceftazidime-resistant P. aeruginosa clinical isolates in four hospitals of southern China. Among these isolates, variable degrees of resistance to other β-lactam and non-β-lactam agents were observed. Pulsed-field gel electrophoresis (PFGE) revealed a high degree of clonality with five main genotypes. Of the 51 isolates tested, 35 (68.6 %) were identified as extended-spectrum β-lactamase (ESBL) producers, with 35 producing PER-1, 1 CTX-M-3, 7 CTX-M-15 and 1 CTX-M-14. Most (82.9 %, 29/35) PER-1-producing isolates were collected from two hospitals between January and April in 2008 and belonged to the same PFGE pattern (pattern B) with similar antibiogram and β-lactamase profiles, which suggested an outbreak of this clone at the time. The prevalence of CTX-M-type ESBL (17.6 %, 9/51) was unexpectedly high. One isolate was identified as producing VIM-2. Furthermore, we also reported an occurrence of a novel OXA-10 variant, OXA-246, in 14 P. aeruginosa isolates. In addition, AmpC overproduction was found to be the β-lactamase-mediated mechanism responsible for ceftazidime resistance in 6 isolates (11.8 %). Our results revealed an overall diversity of β-lactamases and outbreak of a PER-1-producing clone among ceftazidime-resistant P. aeruginosa in southern China.

Prevalence of fusB in Staphylococcus aureus clinical isolates

Fusidic acid (FA) resistance in Staphylococcus aureus markedly varied among different regions. Few data for FA resistance are available in China. In this study, FA susceptibility testing was performed, and the prevalence of fusB and fusC in 116 clinical isolates of S. aureus was investigated by PCR. Mutations in fusA were also determined by sequencing of PCR products. Molecular typing of fusB-positive strains was based on multilocus sequence typing (MLST), spa typing and pulsed-field gel electrophoresis (PFGE). A DNA fragment flanking fusB was sequenced. Transformation experiments were carried out in fusB-positive S. aureus. Of 116 S. aureus including 19 meticillin-resistant S. aureus (MRSA) and 97 meticillin-susceptible S. aureus (MSSA), four (3.5 %) were resistant to FA with MICs of 6–12 µg ml−1, including one MRSA from blood and three MSSA from wound exudates. All four FA-resistant isolates were found to be fusB gene positive. Three FA-resistant MSSA strains had the same MLST profile of ST630 and spa type of t377, whilst the MRSA strain belonged to ST630-t4549. Only one PFGE pattern was recognized for these four strains. No fusC and fusA mutations were detected in any of the isolates. FA resistance in fusB-positive clinical isolates could be transferred to S. aureus RN4220. The fusB gene was located in a transposon-like element, which had 99 % identity with that found in pUB101. In conclusion, the FA resistance rate is low in S. aureus, and the fusB gene is responsible for the resistance.