Polyclonal Burkholderia cepacia Complex Outbreak in Peritoneal Dialysis Patients Caused by Contaminated Aqueous Chlorhexidine.

Whether Burkholderia cepacia complex should be an objectionable organism in antiseptic solutions with acceptable total bacterial counts is controversial. By using next-generation sequencing, we documented a polyclonal B. cepacia complex outbreak affecting peritoneal dialysis patients in Hong Kong that was caused by contaminated chlorhexidine solutions. Epidemiologic investigations at a manufacturing site identified a semiautomated packaging machine as the probable source of contamination in some of the brands. Use of whole-genome sequencing differentiated the isolates into 3 brand-specific clonal types. Changes in exit site care recommendations, rapid recall of affected products, and tightening of regulatory control for chlorhexidine-containing skin antiseptics could prevent future similar outbreaks. Environmental opportunistic pathogens, including B. cepacia complex, might be included in regular surveillance as indicator organisms for monitoring environmental contamination.

Non-specific signals in real-time RT-PCR for detecting respiratory viruses.

We describe our experiences in investigating the origin of non-specific signals during the development phase of a multiplex PCR assay for respiratory viruses. After ruling out various sources of error, eventually we discovered the non-specific signal was related to the particular lot of the PCR kit.

Optimizing heat inactivation for SARS-CoV-2 at 95 °C and its implications: A standardized approach.

Background: Standardized and validated heat inactivation procedure for Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are not available. For heat inactivation, various protocols were reported to prepare External Quality Assessment Programme (EQAP) samples without direct comparison between different durations. Objective: To assess the heat inactivation procedures against SARS-CoV-2. The efficacy of the optimized condition was reflected by the results from laboratories testing the EQAP samples. Study design: The SARS-CoV-2 strain was exposed to 95 °C in a water bath for three different time intervals, 5 min, 10 min and 15 min, respectively. The efficacy of inactivation was confirmed by the absence of cytopathic effects and decreasing viral load in 3 successive cell line passages. The viral stock inactivated by the optimal time interval was dispatched to EQAP participants and the result returned were analyzed. Results: All of the three conditions were capable of inactivating the SARS-CoV-2 of viral load at around cycle threshold value of 10. When the 95 °C 10 min condition was chosen to prepare SARS-CoV-2 EQAP samples, they showed sufficient homogeneity and stability. High degree of consensus was observed among EQAP participants in all samples dispatched. Conclusions: The conditions evaluated in the present study could be helpful for laboratories in preparing SARS-CoV-2 EQAP samples.

Severe underlying liver diseases and high mortality associated with Laribacter hongkongensis bacteremia.

We characterized a strain of Laribacter hongkongensis isolated from the blood of a patient with fatal sepsis, who had alcoholic cirrhosis with ascites and portal hypertension. L. hongkongensis bacteremia is associated with underlying liver diseases (P < 0.001) and mortality (P < 0.05), whereas L. hongkongensis gastroenteritis is associated with recent travel history (P < 0.05).

Measles outbreak from Hong Kong International Airport to the hospital due to secondary vaccine failure in healthcare workers.

OBJECTIVE: To report an outbreak of measles with epidemiological link between Hong Kong International Airport (HKIA) and a hospital. METHODS: Epidemiological investigations, patients' measles serology, and phylogenetic analysis of the hemagglutinin (H) and nucleoprotein (N) genes of measles virus isolates were conducted. RESULTS: In total, 29 HKIA staff of diverse ranks and working locations were infected with measles within 1 month. Significantly fewer affected staff had history of travel than non-HKIA-related measles patients [10 of 29 (34.5%) vs 28 of 35 (80%); P < .01]. Of 9 airport staff who could recall detailed exposure history, 6 (66.7%) had visited self-service food premises at HKIA during the incubation period, where food trays, as observed during the epidemiological field investigation, were not washed after use. Furthermore, 1 airport baggage handler who was admitted to hospital A before rash onset infected 2 healthcare workers (HCWs) known to have 2 doses of MMR vaccination with positive measles IgG and lower viral loads in respiratory specimens. Infections in these 2 HCWs warranted contact tracing of another 168 persons (97 patients and 71 HCWs). Phylogenetic comparison of H and N gene sequences confirmed the clonality of outbreak strains. CONCLUSION: Despite good herd immunity with overall seroprevalence of >95% against measles, major outbreaks of measles occurred among HKIA staff having daily contact with many international pssengers. Lessons from severe acute respiratory syndrome (SARS) and measles outbreaks suggested that an airport can be a strategic epidemic center. Pre-exanthem transmission of measles from airport staff to HCWs with secondary vaccine failure poses a grave challenge to hospital infection control.