Investigation of air dispersal during a rhinovirus outbreak in a pediatric intensive care unit.

BACKGROUND: While airborne transmission of rhinovirus is recognized in indoor settings, its role in hospital transmission remains unclear. METHODS: We investigated an outbreak of rhinovirus in a pediatric intensive care unit (PICU) to assess air dispersal. We collected clinical, environmental, and air samples, and staff's surgical masks for viral load and phylogenetic analysis. Hand hygiene compliance and the number of air changes per hour in the PICU were measured. A case-control analysis was performed to identify nosocomial rhinovirus risk factors. RESULTS: Between March 31, 2023, and April 2, 2023, three patients acquired rhinovirus in a cubicle (air changes per hour: 14) of 12-bed PICU. A portable air-cleaning unit was placed promptly. Air samples (72,000 L in 6 hours) from the cohort area, and outer surfaces of staff's masks (n = 8), were rhinovirus RNA-negative. Hand hygiene compliance showed no significant differences (31/34, 91.2% vs 33/37, 89.2%, P = 1) before and during outbreak. Only 1 environmental sample (3.8%) was positive (1.86 × 103 copies/mL). Case-control and next-generation sequencing analysis implicated an infected staff member as the source. CONCLUSIONS: Our findings suggest that air dispersal of rhinovirus was not documented in the well-ventilated PICU during the outbreak. Further research is needed to better understand the dynamics of rhinovirus transmission in health care settings.

Prevalence and Characteristics of Invasive Staphylococcus argenteus among Patients with Bacteremia in Hong Kong.

Staphylococcus argenteus is a novel Staphylococcus species derived from Staphylococcus aureus. Information on the prevalence and genetic characteristics of invasive S. argenteus in Asia is limited. In this study, 275 invasive S. aureus complex strains were retrieved from blood culture specimens in Hong Kong and re-analyzed using MALDI-TOF mass spectrometry and an in-house multiplex real-time PCR for S. argenteus. The prevalence of invasive S. argenteus in Hong Kong was found to be 4.0% (11/275). These strains were primarily susceptible to commonly used antibiotics, except penicillin. Whole-genome sequencing revealed the circulation of three S. argenteus genotypes (ST-2250, ST-1223, and ST-2854) in Hong Kong, with ST-2250 and ST-1223 being the predominant genotypes. The local ST-2250 and ST-1223 strains showed close phylogenetic relationships with isolates from mainland China. Antimicrobial-resistant genes (fosB, tet-38, mepA, blaI, blaZ) could be found in nearly all local S. argenteus strains. The ST-1223 and ST-2250 genotypes carried multiple staphylococcal enterotoxin genes that could cause food poisoning and toxic shock syndrome. The CRISPR/Cas locus was observed only in the ST-2250 strains. This study provides the first report on the molecular epidemiology of invasive S. argenteus in Hong Kong, and further analysis is needed to understand its transmission reservoir.

Comparative evaluation of a dual-target real-time RT-PCR assay for COVID-19 diagnosis and assessment of performance in pooled saliva and nasopharyngeal swab samples.

OBJECTIVES: Sensitive molecular diagnostic assays are essential for COVID-19 diagnosis. We evaluated the Hecin Scientific SARS-CoV-2 nucleic acid test kit, a dual-target real-time RT-PCR assay targeting the SARS-CoV-2 N and ORF1ab genes. METHODS: The Hecin test kit's diagnostic performance in detecting SARS-CoV-2 RNA was compared to the LightMix Modular SARS and Wuhan CoV E-gene kit (TIB Molbiol) and an in-house single-tube nested real-time RT-PCR using 296 clinical specimens, 11 proficiency testing samples, and 30 low-positive deep throat saliva and nasopharyngeal swab (NPS) samples pooled into negative samples in ratios of 1:5, 1:10, and 1:30. RESULTS: The limit-of-detection of the Hecin test kit was around 500 dC/mL for the N and ORF1ab targets. Sensitivity and specificity of the Hecin test kit were 98.1% (95% CI: 93.4-99.8%) and 100% (98.1-100%), respectively, when measured against the reference method. The Hecin test kit showed fair sensitivity (80%) in low-positive NPS samples pooled in ratios of 1:5 and 1:10. Its performance in pooled samples could be dramatically improved by adjusting the assay Ct cutoff. CONCLUSION: The Hecin test kit enables sensitive and specific detection of SARS-CoV-2 in clinical samples and pooled samples.

Comparative performance of two commercial sample-to-result systems for hepatitis C virus quantitation and genotyping.

OBJECTIVES: Accurate assays for hepatitis C virus (HCV) quantitation and genotyping are important for the management of HCV infection. In this study, we evaluated the performance of cobas HCV and cobas HCV GT assays (Roche) for HCV quantitation and genotyping on the cobas 4800 System. METHODS: We compared the performance of the cobas HCV assays with another commercial system (Abbott m2000) using a panel of well-characterized patient samples and proficiency testing samples. RESULTS: The limit-of-detection of the cobas HCV assay in our center was higher (15 IU/mL) than the manufacturer claim (9.2 IU/mL). The assay showed high analytical specificity, accuracy, precision, and linearity. Performance was congruent with the RealTime HCV assay (Abbott). For genotyping, the cobas HCV GT assay only showed moderate agreement with the RealTime HCV Genotype II assay (kappa = 0.550). The cobas assay outperformed the RealTime assay for typing HCV genotypes 1b and 6 (p = 0.033). CONCLUSION: Our results confirm that the cobas 4800 System is a reliable platform for HCV quantitation and genotyping. The cobas HCV GT assay is a good choice for genotype 1b/6 endemic areas in east Asia, clearly outperforming the RealTime HCV Genotype II assay.

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.

Not sick enough to worry? "Influenza-like" symptoms and work-related behavior among healthcare workers and other professionals: Results of a global survey.

BACKGROUND: Healthcare workers (HCWs) and non-HCWs may contribute to the transmission of influenza-like illness (ILI) to colleagues and susceptible patients by working while sick (presenteeism). The present study aimed to explore the views and behavior of HCWs and non-HCWs towards the phenomenon of working while experiencing ILI. METHODS: The study was a cross-sectional online survey conducted between October 2018 and January 2019 to explore sickness presenteeism and the behaviour of HCWs and non-HCWs when experiencing ILI. The survey questionnaire was distributed to the members and international networks of the International Society of Antimicrobial Chemotherapy (ISAC) Infection Prevention and Control (IPC) Working Group, as well as via social media platforms, including LinkedIn, Twitter and IPC Blog. RESULTS: In total, 533 respondents from 49 countries participated (Europe 69.2%, Asia-Pacific 19.1%, the Americas 10.9%, and Africa 0.8%) representing 249 HCWs (46.7%) and 284 non-HCWs (53.2%). Overall, 312 (58.5%; 95% confidence interval [CI], 56.2-64.6) would continue to work when sick with ILI, with no variation between the two categories. Sixty-seven (26.9%) HCWs and forty-six (16.2%) non-HCWs would work with fever alone (p<0 .01) Most HCWs (89.2-99.2%) and non-HCWs (80%-96.5%) would work with "minor" ILI symptoms, such as sore throat, sinus cold, fatigue, sneezing, runny nose, mild cough and reduced appetite. CONCLUSION: A future strategy to successfully prevent the transmission of ILI in healthcare settings should address sick-leave policy management, in addition to encouraging the uptake of influenza vaccine.

Absence of nosocomial transmission of coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in the prepandemic phase in Hong Kong.

BACKGROUND: To describe the infection control strategy to achieve zero nosocomial transmission of symptomatic coronavirus disease (COVID-19) due to SARS-CoV-2 during the prepandemic phase (the first 72 days after announcement of pneumonia cases in Wuhan) in Hong Kong. METHODS: Administrative support with the aim of zero nosocomial transmission by reducing elective clinical services, decanting wards, mobilizing isolation facilities, providing adequate personal protective equipment, coordinating laboratory network for rapid molecular diagnosis under 4-tier active surveillance for hospitalized patients and outpatients, and organizing staff forum and training was implemented under the framework of preparedness plan in Hospital Authority. The trend of SARS-CoV-2 in the first 72 days was compared with that of SARS-CoV 2003. RESULTS: Up to day 72 of the epidemic, 130 (0.40%) of 32,443 patients being screened confirmed to have SARS-CoV-2 by reverse transcription polymerase chain reaction. Compared with SARS outbreak in 2003, the SARS-CoV-2 case load constituted 8.9% (130 SARS-CoV-2/1458 SARS-CoV) of SARS-CoV infected cases at day 72 of the outbreak. The incidences of nosocomial acquisition of SARS-CoV per 1,000 SARS-patient-day and per 100 SARS-patient-admission were 7.9 and 16.9, respectively, which were significantly higher than the corresponding incidences of SARS-CoV-2 (zero infection, P <.001). CONCLUSIONS: Administrative support to infection control could minimize the risk of nosocomial transmission of SARS-CoV-2.

Escalating infection control response to the rapidly evolving epidemiology of the coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 in Hong Kong.

OBJECTIVE: To describe the infection control preparedness measures undertaken for coronavirus disease (COVID-19) due to SARS-CoV-2 (previously known as 2019 novel coronavirus) in the first 42 days after announcement of a cluster of pneumonia in China, on December 31, 2019 (day 1) in Hong Kong. METHODS: A bundled approach of active and enhanced laboratory surveillance, early airborne infection isolation, rapid molecular diagnostic testing, and contact tracing for healthcare workers (HCWs) with unprotected exposure in the hospitals was implemented. Epidemiological characteristics of confirmed cases, environmental samples, and air samples were collected and analyzed. RESULTS: From day 1 to day 42, 42 of 1,275 patients (3.3%) fulfilling active (n = 29) and enhanced laboratory surveillance (n = 13) were confirmed to have the SARS-CoV-2 infection. The number of locally acquired case significantly increased from 1 of 13 confirmed cases (7.7%, day 22 to day 32) to 27 of 29 confirmed cases (93.1%, day 33 to day 42; P < .001). Among them, 28 patients (66.6%) came from 8 family clusters. Of 413 HCWs caring for these confirmed cases, 11 (2.7%) had unprotected exposure requiring quarantine for 14 days. None of these was infected, and nosocomial transmission of SARS-CoV-2 was not observed. Environmental surveillance was performed in the room of a patient with viral load of 3.3 × 106 copies/mL (pooled nasopharyngeal and throat swabs) and 5.9 × 106 copies/mL (saliva), respectively. SARS-CoV-2 was identified in 1 of 13 environmental samples (7.7%) but not in 8 air samples collected at a distance of 10 cm from the patient's chin with or without wearing a surgical mask. CONCLUSION: Appropriate hospital infection control measures was able to prevent nosocomial transmission of SARS-CoV-2.

Evaluation of RealStar® Alpha Herpesvirus PCR Kit for Detection of HSV-1, HSV-2, and VZV in Clinical Specimens.

Several commercial PCR kits are available for detection of herpes simplex virus (HSV) and varicella zoster virus (VZV), but the test performance of one CE-marked in vitro diagnostic kit-RealStar® alpha Herpesvirus PCR Kit-has not been well studied. This study evaluated the performance of RealStar® alpha Herpesvirus PCR Kit 1.0 on the LightCycler® 480 Instrument II for detection and differentiation of HSV-1, HSV-2, and VZV in human clinical specimens. We evaluated the analytical sensitivity of the RealStar® and in-house multiplex real-time PCR assays using serial dilutions of nucleic acids extracted from clinical specimens. The analytical sensitivity of the RealStar® assay was 10, 32, and 100 copies/reaction for HSV-1, HSV-2, and VZV, respectively, which was slightly higher than that of the in-house multiplex real-time PCR assay. Reproducibility of the cycle threshold (Cp) values for each viral target was satisfactory with the intra- and interassay coefficient of variation values below 5% for both assays. One-hundred and fifty-three clinical specimens and 15 proficiency testing samples were used to evaluate the diagnostic performance of RealStar® alpha Herpesvirus PCR Kit against the in-house multiplex real-time PCR assay. The RealStar® assay showed 100% sensitivity and specificity when compared to the in-house assay. Cp values of the RealStar® and in-house assays showed excellent correlation. RealStar® alpha Herpesvirus PCR is a sensitive, specific, and reliable assay for the detection of HSV-1, HSV-2, and VZV, with less extensive verification requirements compared to a laboratory developed assay.

Epidemiological and Clinical Characteristics of Human Hepegivirus 1 Infection in Patients With Hepatitis C.

BACKGROUND: Transmission of human hepegivirus 1 (HHpgV-1), a novel human pegivirus, is closely associated with hepatitis C virus (HCV). The impact of HHpgV-1 viremia on HCV infection is unknown. This study aimed to (a) evaluate the impact of HHpgV-1 viremia on HCV viral load and liver injury and (b) elucidate the clinical and molecular epidemiology of HHpgV-1 infection. METHODS: Individuals with HHpgV-1 viremia (cases) were identified by screening plasma from 655 HCV-infected adults. HHpgV-1 isolates were sequenced for phylogenetic analysis, and viral load was quantified. Cases were age- and sex-matched to HCV-infected individuals without HHpgV-1 viremia (controls) in a 1:3 ratio. A retrospective case-control analysis was performed to identify differences in HCV viral load and parameters of liver injury. RESULTS: Among HCV-infected adults, 16/655 (2.4%) had HHpgV-1 viremia. Risk groups for HHpgV-1 infection included intravenous drug users, blood product recipients, tattoo recipients, and men who have sex with men. Viral sequences clustered into 2 distinct HHpgV-1 genogroups. Cases had a higher mean HCV viral load than controls, with difference between means of 0.58 log10 IU/mL (P = .009). Cases were more likely to have an HCV viral load >5 log10 IU/mL (P = .028). Multiple regression demonstrated the impact of HHpgV-1 viral load and infection status on HCV viral load. HHpgV-1 infection was not associated with higher liver function tests, fibrosis scores, or imaging abnormalities. CONCLUSIONS: HHpgV-1 viremia is associated with a higher HCV viral load in co-infected patients. HHpgV-1 infection does not affect progression of HCV-related liver disease.

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.

Improving the specific diagnosis of trematode, cestode and nematode infections by a multiplex single-tube real-time PCR assay.

AIMS: Helminth infections are becoming uncommon in high-income countries and laboratory staff may lose expertise in their morphological identification, especially in histological sections where speciation of helminths is challenging. Commercially available molecular diagnostic panels for faecal specimens only offer tests for protozoa but not helminths. We aim to improve the identification accuracy of helminths using a multiplex PCR assay. METHODS: We designed three pairs of PCR primers and probes targeting multicopy genes for a multiplex single-tube real-time PCR assay which covers 16 trematode (28S rRNA gene), 24 cestode (cox1 gene) and 33 nematode (cox1 gene) species. Helminths (n=27) from faecal samples (n=10), fresh parasites (n=11), formalin-fixed specimens (n=4), cerebrospinal fluid (n=1) and bile (n=1) were examined morphologically and tested by PCR. Fifty stool samples negative for parasites by microscopy were also tested. RESULTS: The PCR assay correctly identified the genera of all tested helminths. Agarose gel electrophoresis and sequencing of the purified PCR amplicons confirmed that the PCR products were of correct sizes with 100% correlation with the respective species. Sequencing of the cox1 gene failed to identify Capillaria spp. in one sample owing to the lack of corresponding sequences in GenBank. PCR and sequencing of the nematode 18S rRNA gene using consensus primers showed 100% homology with Capillaria spp. sequence. No positive PCR products were found in the negative stool samples. CONCLUSIONS: The highly specific test correctly identified all helminths in our cohort. It is a useful adjunct to helminth identification in difficult situations such as histological sections.

Donor-Derived Genotype 4 Hepatitis E Virus Infection, Hong Kong, China, 2018.

Hepatitis E virus (HEV) genotype 4 (HEV-4) is an emerging cause of acute hepatitis in China. Less is known about the clinical characteristics and natural history of HEV-4 than HEV genotype 3 infections in immunocompromised patients. We report transmission of HEV-4 from a deceased organ donor to 5 transplant recipients. The donor had been viremic but HEV IgM and IgG seronegative, and liver function test results were within reference ranges. After a mean of 52 days after transplantation, hepatitis developed in all 5 recipients; in the liver graft recipient, disease was severe and with progressive portal hypertension. Despite reduced immunosuppression, all HEV-4 infections progressed to persistent hepatitis. Four patients received ribavirin and showed evidence of response after 2 months. This study highlights the role of organ donation in HEV transmission, provides additional data on the natural history of HEV-4 infection, and points out differences between genotype 3 and 4 infections in immunocompromised patients.

Whole-genome sequencing data-based modeling for the investigation of an outbreak of community-associated methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit in Hong Kong.

We describe a nosocomial outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) ST59-SCCmec type V in a neonatal intensive care unit (NICU) in Hong Kong. In-depth epidemiological analysis was performed by whole-genome sequencing (WGS) of the CA-MRSA isolates collected from patients and environment during weekly surveillance and healthcare workers from the later phase of the outbreak. Case-control analysis was performed to analyze potential risk factors for the outbreak. The outbreak occurred from September 2017 to February 2018 involving 15 neonates and one healthcare worker. WGS analysis revealed complicated transmission dynamics between patients, healthcare worker, and environment, from an unrecognized source introduced into the NICU within 6 months before the outbreak. In addition to enforcement of directly observed hand hygiene, environmental disinfection, cohort nursing of colonized and infected patients, together with contact tracing for secondary patients, medical, nursing, and supporting staff were segregated where one team would care for CA-MRSA-confirmed/CA-MRSA-exposed patients and the other for newly admitted patients in the NICU only. Case-control analysis revealed use of cephalosporins [odds ratio 49.84 (3.10-801.46), p = 0.006] and length of hospitalization [odds ratio 1.02 (1.00-1.04), p = 0.013] as significant risk factors for nosocomial acquisition of CA-MRSA in NICU using multivariate analysis. WGS facilitates the understanding of transmission dynamics of an outbreak, providing insights for outbreak prevention.

Emergence of Cytomegalovirus Mononucleosis Syndrome Among Young Adults in Hong Kong Linked to Falling Seroprevalence: Results of a 14-Year Seroepidemiological Study.

BACKGROUND: Cytomegalovirus (CMV) mononucleosis is a manifestation of primary CMV infection. This study aims to establish the link between long-term population CMV seroepidemiological trends and incidence of CMV mononucleosis requiring hospitalization. Furthermore, by analyzing serial laboratory data of patients hospitalized with CMV mononucleosis, we aim to provide insights into the natural history of this syndrome. METHODS: We conducted a 14-year observational study in a tertiary hospital in Hong Kong. Cytomegalovirus immunoglobulin G data of 2349 adults were analyzed for trends in CMV susceptibility during the study period. The clinical features, risk factors, antiviral treatment data, and laboratory findings of 25 adult patients presenting with CMV mononucleosis during this period were retrieved. RESULTS: Susceptibility to CMV infection among the adult population aged 18-45 in Hong Kong increased from 14.5% in 2004 to 32.2% in 2012-2017 (P < .001), and this led to doubling of observed CMV mononucleosis incidence among inpatients in our center during the study period. All patients with CMV mononucleosis were hospitalized for investigation of fever of unknown origin. Household contact with young children was the most common risk factor followed by recent overseas travel. Derangement of liver function tests was universally observed and was more severe than in previously published western CMV mononucleosis patient cohorts. Most patients showed clinical improvement within the third week of illness. CONCLUSIONS: We conclude that increasing CMV susceptibility among young adults in Hong Kong has resulted in a rising observed incidence of CMV mononucleosis, which is typically a self-limited illness characterized by anicteric hepatitis.

Rat Hepatitis E Virus as Cause of Persistent Hepatitis after Liver Transplant.

All hepatitis E virus (HEV) variants reported to infect humans belong to the species Orthohepevirus A (HEV-A). The zoonotic potential of the species Orthohepevirus C (HEV-C), which circulates in rats and is highly divergent from HEV-A, is unknown. We report a liver transplant recipient with hepatitis caused by HEV-C infection. We detected HEV-C RNA in multiple clinical samples and HEV-C antigen in the liver. The complete genome of the HEV-C isolate had 93.7% nt similarity to an HEV-C strain from Vietnam. The patient had preexisting HEV antibodies, which were not protective against HEV-C infection. Ribavirin was an effective treatment, resulting in resolution of hepatitis and clearance of HEV-C viremia. Testing for this zoonotic virus should be performed for immunocompromised and immunocompetent patients with unexplained hepatitis because routine hepatitis E diagnostic tests may miss HEV-C infection. HEV-C is also a potential threat to the blood product supply.

Idiopathic granulomatous mastitis: a 10-year study from a multicentre clinical database.

Idiopathic granulomatous mastitis (IGM) is an uncommon, chronic inflammatory breast disease with elusive aetiology, simulating malignancy clinically and radiologically. Here we present our 10-year review on a region-wide multicentre IGM database. A retrospective study was performed on a prospectively maintained database from three University affiliated hospitals in Hong Kong and Shenzhen, China. All patients with biopsy proven IGM were included while patients with positive culture of Mycobacterium tuberculosis were excluded. Disease recurrence rate and its prognosticators were evaluated. A total of 102 patients were included between January 2007 and December 2017. Median age was 33 years (range 20-54). Most patients presented with painful inflammatory mass (n = 57); median size at presentation was 37 mm (6-92 mm). Sixty-three patients had bacterial culture performed on the pus sample: eight patients had Corynebacterium kroppenstedtii while four had Corynebacterium species not otherwise specified. Seventy-seven (75.5%) patients received conservative treatment with oral corticosteroid (±antibiotics) and drainage only, while 25 (24.5%) patients received breast lump excision after initial medical treatment. Twelve (11.8%) patients developed recurrence after a median follow-up interval of 14 months (4-51 months). Univariate analysis revealed that abscess on presentation, history of smoking, and presence of C. kroppenstedtii were significant prognosticators for recurrence. Subsequent multivariate analysis with logistic regression revealed cigarette smoking and isolation of C. kroppenstedtii as independent risk factors for disease recurrence (p < 0.05). In conclusion, IGM is uncommon with a recurrence rate of 12%, especially in patients with history of smoking and isolation of C. kroppenstedtii.

Comparative evaluation of a laboratory-developed real-time PCR assay and RealStar® Adenovirus PCR Kit for quantitative detection of human adenovirus.

BACKGROUND: Human adenoviruses are common causes of community-acquired respiratory tract and enteric infections. Severe disseminated infections with high mortality rates may be seen in immunocompromised individuals. An accurate and cost-effective quantitative assay is essential not only for laboratory diagnosis of adenoviral infections, but also for monitoring of response to antiviral treatment. The diagnostic performance of an in-house quantitative polymerase chain reaction assay was compared to a commercial system. METHODS: The analytical sensitivity, specificity, linearity, precision and accuracy of an in-house adenovirus quantitative polymerase chain reaction assay were evaluated against the RealStar® Adenovirus PCR Kit (Altona Diagnostics GmbH, Hamburg, Germany), using 122 clinical specimens and 18 proficiency testing samples. RESULTS: Linear regression analysis of the quantitative results by the in-house assay showed the dynamic range from 2.60 to 9 log10 (plasma) and 2.94 to 9 log10 (viral transport medium) copies/mL, with the coefficient of determination (R2) of 0.996 and 0.998, respectively. A dilution series demonstrated the limits of detection and lower limits of quantification for plasma were 2.06 log10 and 2.60 log10 copies/mL and those for viral transport medium were 2.31 log10 and 2.94 log10 copies/mL respectively. The precision of the in-house assay was highly reproducible among runs with coefficients of variance ranging from 0.07 to 3.21% for plasma and 0.17% to 2.11% for viral transport medium. A comparison of 52 matched samples showed an excellent correlation between the quantitative viral loads measured by the in-house assay and the RealStar® Adenovirus PCR Kit (R2 = 0.984), with an average bias of - 0.16 log10 copies/mL. CONCLUSIONS: The in-house adenovirus assay is a sensitive and reliable assay with lower cost for the detection and quantification of adenoviral DNA when compared to the RealStar® Adenovirus PCR Kit.

Nosocomial transmission of hepatitis C virus in a liver transplant center in Hong Kong: implication of reusable blood collection tube holder as the vehicle for transmission.

BACKGROUND: A liver transplant recipient developed hospital-acquired symptomatic hepatitis C virus (HCV) genotype 6a infection 14 months post transplant. OBJECTIVE: Standard outbreak investigation. METHODS: Patient chart review, interviews of patients and staff, observational study of patient care practices, environmental surveillance, blood collection simulation experiments, and phylogenetic study of HCV strains using partial envelope gene sequences (E1-E2) of HCV genotype 6a strains from the suspected source patient, the environment, and the index patient were performed. RESULTS: Investigations and data review revealed no further cases of HCV genotype 6a infection in the transplant unit. However, a suspected source with a high HCV load was identified. HCV genotype 6a was found in a contaminated reusable blood-collection tube holder with barely visible blood and was identified as the only shared item posing risk of transmission to the index case patient. Also, 14 episodes of sequential blood collection from the source patient and the index case patient were noted on the computerized time log of the laboratory barcoding system during their 13 days of cohospitalization in the liver transplant ward. Disinfection of the tube holders was not performed after use between patients. Blood collection simulation experiments showed that HCV and technetium isotope contaminating the tip of the sleeve capping the sleeved-needle can reflux back from the vacuum-specimen tube side to the patient side. CONCLUSIONS: A reusable blood-collection tube holder without disinfection between patients can cause a nosocomial HCV infection. Single-use disposable tube holders should be used according to the recommendations by Occupational Safety and Health Administration and World Health Organization.