Exhaled air dispersion and removal is influenced by isolation room size and ventilation settings during oxygen delivery via nasal cannula.

BACKGROUND AND OBJECTIVE: We compared the exhaled air dispersion distances during oxygen delivery via nasal cannula to a human-patient simulator (HPS) in two different isolation rooms. METHODS: Airflow was marked with intrapulmonary smoke for visualization. Oxygen flow was gradually increased from 1 to 5 L/min, with the HPS sitting at 45°. The leakage jet plume was revealed by laser light-sheet and images captured by high-definition video. Smoke concentration in the plume was estimated from the light scattered by smoke particles. The experiments were conducted at a double-door, negative pressure isolation room with a dimension of 4.1 × 5.1 × 2.6 m, pressure of -7.4 Pa and 16 air exchanges/h (ACH) (room A). Results were compared with experiments repeated in a smaller isolation room with a dimension of 2.7 × 4.2 × 2.4 m, pressure of -5 Pa and 12 ACH (room B). RESULTS: Room A: an exhalation jet spread almost horizontally outward from the nostrils of the HPS to 0.66 m and 1 m towards the end of bed when oxygen flow was increased from 1 to 5 L/min respectively. Room B: there was interaction between the downward ceiling ventilation current and the exhaled air from the HPS, leading to deflection of exhaled smoke towards the head of the HPS at an oxygen flow rate of 1 L/min. As oxygen flow was increased gradually to 5 L/min, more room contamination with smoke was noted. CONCLUSIONS: Substantial exposure to exhaled air occurs within 1 m towards the end of the bed from patients receiving oxygen via nasal cannula. Room dimension and air exchange rate are important factors in preventing contamination in isolation rooms.

Viral load in patients infected with pandemic H1N1 2009 influenza A virus.

Viral shedding profile of infections caused by the pandemic H1N1 2009 influenza A virus has not been reported. The aim of this study was to determine the viral load in different body sites. Viral loads of pandemic H1N1 virus in respiratory specimens, stool, urine, and serum were determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Respiratory specimens from patients with seasonal influenza were used as historical controls. Initial pre-treatment viral load were compared between these two groups. Serial respiratory specimens from patients with pandemic H1N1 virus infection were obtained for analysis of viral dynamics. Twenty-two pandemic H1N1 cases and 44 seasonal influenza historical controls were included. The mean initial viral load before oseltamivir therapy was 1.84 x 10(8) copies/ml for pandemic H1N1 virus compared with 3.28 x 10(8) copies/ml in seasonal influenza historical controls (P = 0.085). Among patients with pandemic H1N1 virus infection, peak viral load occurred on the day of onset of symptoms, and declined gradually afterwards, with no virus being detectable in respiratory specimens by RT-PCR 8 days and by culture 5 days after the onset of symptoms respectively, except in one patient. Pandemic H1N1 virus was detected in stool and in urine from 4/9 and 1/14 patients, respectively. Viral culture was also positive from the stool sample with the highest viral load. Younger age was associated with prolonged shedding in the respiratory tract and higher viral load in the stool. Data from this quantitative analysis of viral shedding may have implications for formulating infection control measures.

Erratum to: Mutational analysis of 65 Wilson disease patients in Hong Kong Chinese: Identification of 17 novel mutations and its genetic heterogeneity.

The correct name of the eighth author should be given as Sik-To Lai, not Jak-Yiu Lai.

Management and outcome of peptic ulcers or erosions in patients receiving a combination of aspirin plus clopidogrel.

BACKGROUND: This multicenter retrospective study investigated the management and outcome of patients with peptic ulcer/erosion-related aspirin and clopidogrel (A + C) cotherapy. METHODS: From January 2002 to September 2006, patients with endoscopically proven peptic ulcers/erosions after receiving A + C cotherapy were analyzed. RESULTS: This group consisted of 106 patients (age, 69.3 +/- 11.7 years). Ulcers/erosions developed in 27 patients during hospitalization for cardiac events and in 79 patients after hospital discharge. Of 27 patients hospitalized for acute cardiac events, gastrointestinal (GI) bleeding and dyspepsia occurred in 24 and three, respectively. The most common lesion was gastric ulcer. Of 79 discharged patients, GI bleeding and dyspepsia occurred in 64 and 15, respectively. The most common bleeding and dyspeptic lesions were gastric ulcer and gastritis, respectively. Overall, 17 patients underwent endoscopic hemostasis all successfully. A + C cotherapy was continued in 57 patients for a median (interquartile range) of 3.0 (6.2) months. Most were coprescribed a proton pump inhibitor (PPI) (53, 93%). No recurrent GI bleeding was observed. CONCLUSIONS: After A + C cotherapy, gastric ulcer or gastritis were the most common endoscopic lesions. The combination of a PPI and endoscopic treatment for ulcer bleeding was highly successful. After patient stabilization, continuation of A + C cotherapy with a PPI appears to be safe.

Rapid diagnosis of Wilson disease by a 28-mutation panel: real-time amplification refractory mutation system in diagnosing acute Wilsonian liver failure.

BACKGROUND: Wilson disease is one of the commonest inherited and potentially fatal yet treatable liver disorders. About 5-27% patients present with acute liver failure and require prompt chelation therapy and life-saving liver transplantation. Diagnosis during acute liver failure is particularly difficult with short time allowance. Direct molecular diagnosis remains the most decisive tool but is often hindered by demanding techniques and numerous mutations. We developed a one-step, 3-h, reproducible, and accurate real-time amplification refractory mutation system which can simultaneously detect 28 ATP7B mutations. METHODS: Primers were designed to complement the mutant sequence at the 3' end. The mutations were p.S105X, p.Q511X, p.R616Q, p.S693P, p.S693C, p.R778L, p.A874V, p.T888P, p.R919G, p.T935M, p.P992L, p.M1025R, p.D1047V, p.I1148T, p.R1156H, p.T1178A, p.V1216M, p.P1273Q, p.G1281C, p.R1320S, p.V1334D, p.V176SfsX28, p.G869EfsX4, IVS3+1G>T, IVS4-1G>C, IVS4-5T>G, IVS6+9A>G, and IVS9+5G>T. Reaction was performed using QuantiTect SYBR Green PCR Master Mix on an Applied Biosystems StepOne thermal cycler. Values of the threshold cycle were compared between normal and mutant alleles. RESULTS: Primers of all mutations were highly specific with absence of wild-type amplification. All the results were validated by direct DNA sequencing. CONCLUSIONS: This rapid and cost-efficient method allows wide mutation coverage, rendering the SYBR-green assay feasible and attractive for large-scale routine application.

Epstein-Barr virus-associated smooth muscle tumor in patients with acquired immunodeficiency syndrome.

Epstein-Barr virus (EBV)-associated smooth muscle tumor (SMT) is a recognized but uncommon disease that is found to occur in patients with immunocompromised conditions such as acquired immunodeficiency syndrome (AIDS). These tumors may be multifocal and located at unusual sites, such as the brain and liver. This report describes the case of 2 AIDS patients with EBV-associated SMT and highlights the features and outcome of this rare but potentially important tumor in human immunodeficiency virus management.

Myopathic changes associated with severe acute respiratory syndrome: a postmortem case series.

BACKGROUND: The March 2003 outbreak of the severe acute respiratory syndrome (SARS) resulted in significant morbidity and mortality. Muscle weakness and elevated serum creatine kinase levels are commonly encountered in patients with SARS. However, the nature and cause of myopathy associated with a SARS infection are unknown because, to our knowledge, there has been no report of histological or postmortem examination of the skeletal muscle from SARS-infected patients. OBJECTIVE: To determine the exact nature of the myopathy associated with SARS. METHOD: Postmortem skeletal muscles from 8 consecutive patients who died of SARS in March 2003 were studied under light and electron microscopy as well as immunohistochemistry. RESULTS: Focal myofiber necrosis was identified in 4 of 8 cases. Macrophage infiltration and regenerative fiber were scanty. All 4 patients treated with a steroid had significant myofiber atrophy. In situ hybridization for coronavirus was negative in all subjects. Viral cultures for coronavirus and examination for viral particles under electron microscopy were performed in 2 patients. The viral culture yielded no organisms and there were no viral particles seen on electron microscopic examination. CONCLUSIONS: There is a spectrum of myopathic changes associated with a SARS infection. Focal myofiber necrosis is common and possibly is immune mediated. Critical illness myopathy and superimposed steroid myopathy may also play an important role in SARS.

Clinical significance of hepatic derangement in severe acute respiratory syndrome.

AIM: Elevation of alanine aminotransferase (ALT) level is commonly seen among patients suffering from severe acute respiratory syndrome (SARS). We report the progression and clinical significance of liver derangement in a large cohort of SARS patient. METHODS: Serial assay of serum ALT was followed in patients who fulfilled the WHO criteria of SARS. Those with elevated ALT were compared with those with normal liver functions for clinical outcome. Serology for hepatitis B virus (HBV) infection was checked. Adverse outcomes were defined as oxygen desaturation, need of intensive care unit (ICU) and mechanical ventilation and death. RESULTS: Two hundred and ninety-four patients were included in this study. Seventy (24%) patients had elevated serum ALT on admission and 204 (69%) patients had elevated ALT during the subsequent course of illness. Using peak ALT >5XULN as a cut-off and after adjusting for potential confounding factors, the odds ratio of peak ALT >5X ULN for oxygen desaturation was 3.24 (95%CI 1.23-8.59, P = 0.018), ICU care was 3.70 (95%CI 1.38-9.89, P = 0.009), mechanical ventilation was 6.64 (95%CI 2.22-19.81, P = 0.001) and death was 7.34 (95%CI 2.28-24.89, P = 0.001). Ninety-three percent of the survived patients had ALT levels normalized or were on the improving trend during follow-up. Chronic hepatitis B was not associated with worse clinical outcomes. CONCLUSION: Reactive hepatitis is a common complication of SARS-coronavirus infection. Those patients with severe hepatitis had worse clinical outcome.

Outcomes and prognostic factors in 267 patients with severe acute respiratory syndrome in Hong Kong.

BACKGROUND: Severe acute respiratory syndrome (SARS) has become a global public health emergency. OBJECTIVE: To evaluate the characteristics and outcomes of patients with SARS in Hong Kong and to identify predictors of mortality. DESIGN: Retrospective cohort study. SETTING: Quarantine hospital for patients with SARS in Hong Kong. PATIENTS: 267 consecutive patients hospitalized from 26 February to 31 March 2003 for probable or confirmed SARS. MEASUREMENTS: Clinical, laboratory, and radiographic measures; 3-month mortality rate. RESULTS: According to our case definition, there were 227 cases of confirmed SARS and 40 cases of probable SARS. Common presenting symptoms were fever (99% of patients), chills (74%), malaise (63%), and myalgia (50%). Laboratory findings included lymphopenia (73%), thrombocytopenia (50%), hyponatremia (60%), and elevated levels of lactate dehydrogenase (47%) and C-reactive protein (75%). During hospitalization, incidence of diarrhea (53%), anemia (53%), and acute renal failure (6%) increased. Sixty-nine patients (26%) required intensive care because of respiratory failure. The 3-month mortality rate was 12% (95% CI, 8% to 16%). Factors contributing to mortality were respiratory failure, acute renal failure, and nosocomial sepsis. On multivariate Cox regression, age older than 60 years (relative risk, 5.10 [CI, 2.30 to 11.31]; P < 0.001) and lactate dehydrogenase level greater than 3.8 micro kat/L at presentation (relative risk, 2.20 [CI, 1.03 to 4.71]; P = 0.04) were independent predictors of mortality. CONCLUSION: Because of the longer follow-up period in our cohort, the mortality rate in these patients is higher than rates reported in previous studies. Advanced age and high lactate dehydrogenase level at presentation predict mortality. *For members of the Princess Margaret Hospital SARS Study Group, see the Appendix.

Value of initial chest radiographs for predicting clinical outcomes in patients with severe acute respiratory syndrome.

PURPOSE: To determine whether the initial chest radiograph is helpful in predicting the clinical outcome of patients with severe acute respiratory syndrome (SARS). METHODS: Of 343 patients who met the World Health Organization's case definition of probable SARS and who had been admitted to a regional hospital in Hong Kong, 201 patients had laboratory evidence of SARS coronavirus infection. The initial frontal chest radiographs of these 201 patients were assessed in a blinded fashion by 3 radiologists; individual findings were accepted if at least 2 of the radiologists concurred. Independent predictors of an adverse outcome, defined as the need for assisted ventilation, death, or both, were identified by multivariate analysis. RESULTS: Bilateral disease and involvement of more than two zones on the initial chest radiograph were associated with a higher risk of liver impairment and poor clinical outcome. Forty-two patients (21%) developed an adverse outcome. Multivariate analysis showed that lung involvement of more than two zones (odds ratio [OR] = 7.0; 95% confidence interval [CI]: 2.7 to 17.9), older age (OR for each decade of life = 1.5; 95% CI: 1.1 to 2.0), and shortness of breath on admission (OR = 2.8; 95% CI: 1.1 to 7.4) were independent predictors of an adverse outcome. CONCLUSION: Frontal chest radiographs on presentation may have prognostic value in patients with SARS.

Transjugular liver biopsy with an automated trucut-type needle: comparative study with percutaneous liver biopsy.

OBJECTIVE: Transjugular liver biopsy using the suction method usually produces small specimens with excessive fragmentation, hence the diagnosis adequacy of specimens and the clinical impact of performing the biopsy have been questioned. An alternative biopsy needle, the Quick-Core needle system, which uses an automated trucut-type mechanism, has been shown to produce non-fragmented tissue specimens. The aim of the present study was to evaluate the safety, adequacy and clinical impact of the transjugular liver biopsy by comparing it with the standard percutaneous liver biopsy. DESIGN: We recruited all patients who underwent liver biopsies by percutaneous or transjugular routes in the Department of Medicine, Princess Margaret Hospital, Hong Kong between January 1998 and December 1999. METHOD: We recorded demographics and clinical features of patients, indications and complications, and the clinical impact of the liver biopsy procedure. All liver biopsy specimens were reviewed by the histopathologist, who was blinded to the approach of taking the biopsy. All variables between patients undergoing transjugular and percutaneous liver biopsies were compared. RESULTS: During the study period, 50 percutaneous and 18 transjugular liver biopsies were performed. All transjugular liver biopsies were performed successfully with adequate tissue for diagnosis. Although specimens obtained by the transjugular technique tended to be shorter (10 mm v. 18 mm by the percutaneous approach, P < 0.001), the presence of fragmentation was similar to that in biopsies obtained by the percutaneous approach. Respectively, 100% and 98% of specimens obtained by the transjugular and percutaneous approaches were considered to be adequate for histological assessment. The clinical impact of transjugular and percutaneous liver procedures was comparable (89% v. 76%, P = 0.25). CONCLUSION: Specimens obtained by a transjugular automated trucut needle are sufficient for histological assessment, and carry clinical impact in patient management.

Look-back investigation of a health care worker infected with human immunodeficiency virus.

We report the referral of an HIV-infected surgeon and a subsequent first-ever recommended look-back investigation in Hong Kong. Efficient coordination and effective implementation of the look-back investigation yielded a high response rate of 92.3% of priority patients, with none tested HIV positive. Our experience reconfirmed the very small risk of provider-to-patient HIV transmission and the crucial importance of infection control.

Non-invasive screening of HLA-DPA1 and HLA-DPB1 alleles for persistent hepatitis B virus infection: susceptibility for vertical transmission and toward a personalized approach for vaccination and treatment.

BACKGROUND: Polymorphisms in the major histocompatibility complex (MHC) and non-MHC genes were recently reported to be associated with persistent hepatitis B virus (HBV) infection and host response to hepatitis B vaccine in Asian populations. We aimed to confirm the associations in Chinese population and develop a non-invasive screening method for the risk loci. METHODS: We genotyped 2 risk alleles on the MHC loci, HLA-DPA1 (rs3077) and HLA-DPB1 (rs9277535), and 1 risk allele near a non-MHC gene, FOXP1 (rs6789153) using high-resolution melting curve analysis. With minimal processing steps and time, salivary DNA was extracted with a modified protocol of a blood kit. We compared the genotyping fidelity between peripheral blood DNA and salivary DNA. RESULTS: Both rs3077 and rs9277535, but not rs6789153, are significantly associated with CHB in Chinese population (p-value<0.001). High genotype concordance between different sources of genomic DNA was obtained. CONCLUSIONS: Genotyping salivary DNA using our modified methods provides a non-invasive fast screening for host susceptibility loci. The transmission mechanism of hepatitis B can now be modified by adding genetic susceptibility to the traditional vertical transmission model of hepatitis B.

Review of vector-borne diseases in Hong Kong.

The epidemiology of vector-borne diseases in Hong Kong has changed over the past decade but still poses a significant public health risk. We provided a comprehensive review of the epidemiological information and analysed the trends of major vector-borne diseases, including the vector situation in Hong Kong. The incidence of malaria has dropped dramatically in the past few decades and is now mainly an imported disease acquired from malaria endemic countries. Locally acquired dengue fever occurred in 2002 and 2003, and thereafter all cases were imported, mainly from Southeast Asia areas. Only a few local cases of Japanese encephalitis were reported in the past decade. In contrast, there is a notable increase in scrub typhus and spotted fever cases. The emergence of chikungunya fever in Asia and Indian Ocean countries also resulted in importation of human cases. Given the heavy traffic between this international city and other parts of the world, as well as the presence of vectors in this densely populated area, vigilance should be maintained against these infections. Comprehensive public health measures encompassing disease surveillance, vector surveillance and control measures with support from all sectors of the community are required to combat the old and newly emerging vector-borne diseases in Hong Kong.

The natural viral load profile of patients with pandemic 2009 influenza A(H1N1) and the effect of oseltamivir treatment.

BACKGROUND: The natural history of viral shedding from the upper respiratory tract of the new pandemic 2009 influenza A(H1N1) and the effect of oseltamivir treatment were uncertain. METHODS: A retrospective cohort study involving 145 consecutive patients with specimens positive by reverse transcriptase-polymerase chain reaction for the matrix and new H1 genes was conducted. RESULTS: The nontreated and oseltamivir-treated patients were comparable in their viral load at presentation, demography, and the presenting symptoms. No correlation was observed between viral load with age and number of symptoms. Viral load of nasopharyngeal aspirate (NPA) was significantly lower in treated than in nontreated patients at day 5 after symptom onset. When oseltamivir was initiated 2 days of symptom onset. The viral load was inversely correlated with concomitant absolute lymphocyte count in nontreated patients (Pearson correlation coefficient [r] = -0.687, P = .001) and treated patients (Pearson r = -0.365, P < .001). Resolution of fever was 1.4 days later in nontreated than treated patients (P = .012) CONCLUSIONS: The natural viral load profile was described. Oral oseltamivir suppresses viral load more effectively when given early in mild cases of pandemic 2009 influenza A(H1N1) infections.

CD209 (DC-SIGN) -336A>G promoter polymorphism and severe acute respiratory syndrome in Hong Kong Chinese.

CD209 (DC-SIGN) is an important C-type lectin which acts a receptor of many pathogens. The single nucleotide polymorphism (SNP) -336A>G in the CD209 promoter has been demonstrated to regulate promoter activity and to be associated with several important infectious diseases, such as human immunodeficiency virus-1 (HIV-1), Mycobacterium tuberculosis, and Dengue fever. CD209 facilitates severe acute respiratory syndrome (SARS)-coronavirus spike protein-bearing pseudotype driven infection of permissive cells in vitro. In keeping with previously published findings, our in vitro studies confirmed that this SNP modulates gene promoter activity. Genetic association analysis of this SNP with clinico-pathologic outcomes in 824 serologic confirmed SARS patients showed that the -336AG/GG genotype SARS patients was associated with lower standardized lactate-dehydrogenase (LDH) levels compared with the -336AA patients (p = 0.014, odds ratio = 0.40). High LDH levels are known to be an independent predictor for poor clinical outcome, probably related to tissue destruction from immune hyperactivity. Hence, SARS patients with the CD209 -336 AA genotype carry a 60% chance of having a poorer prognosis. This association is in keeping with the role of CD209 in modulating immune response to viral infection. The relevance of these findings for other infectious diseases and inflammatory conditions would be worth investigating.

Risk factors associated with life-threatening rickettsial infections.

We retrospectively analyzed 92 cases of severe rickettsial infections in patients (median age = 49 years, 57% male, 37.0% with scrub typhus) in Hong Kong. Immunofluorescence assay was used for diagnostic confirmation. Identification of > or = 1 diagnostic sign (exposure history, rash, or eschar) was possible in 94.6% of the cases. Multivariate analysis suggested that pulmonary infiltrates (odds ratio [OR] = 25.2, 95% confidence interval [CI] = 3.9-160.9, P = 0.001) and leukocytosis (OR = 1.3, 95% CI = 1.0-1.5 per unit increase, P = 0.033) were independent predictors of admission to an intensive care unit (14.1%). Delayed administration of doxycycline was independently associated with major organ dysfunction (23.9%; oxygen desaturation, renal failure, severe jaundice, encephalopathy, cardiac failure) (OR = 1.2, 95% CI = 1.0-1.5 per day delay, P = 0.046; adjusted for age and rickettsia biogroup) and prolonged hospitalization > 10 days (25%) (OR = 1.4, 95% CI = 1.1-1.9 per day delay, P = 0.014). Treatment with fluoroquinolone/clarithromycin did not correlate with clinical outcomes (P > 0.05). Early empirical doxycycline therapy should be considered if clinico-epidemiologic signs of rickettsial infections are present.

Sustained disease remission after spontaneous HBeAg seroconversion is associated with reduction in fibrosis progression in chronic hepatitis B Chinese patients.

UNLABELLED: Recently, controversies have arisen about whether hepatitis B e antigen (HBeAg) seroconversion can result in regression of fibrosis, thus improving the clinical outcome of Chinese patients with chronic hepatitis B. In this study, we determined if spontaneous HBeAg seroconversion is associated with regression of fibrosis in Chinese chronic hepatitis B patients. We evaluated the histology of liver samples from 128 HBeAg-positive treatment-naive Chinese patients who had undergone 2 liver biopsies over the years. Regression of fibrosis was defined as a decrease in fibrosis stage of at least 1 point. Sustained disease remission was defined as HBeAg seroconversion and hepatitis B virus (HBV) DNA < 10(4) copies/ml at follow-up liver biopsy. The mean duration (+/- standard error of the mean) between the initial and follow-up liver biopsies was 43.9 +/- 3.4 months. Regression of fibrosis was higher in patients with sustained disease remission (5 of 13 [38.5%] versus 22 of 115 [19.1%], P < 0.00005), patients who were younger (20-29 years old) at initial liver biopsy (17 of 54 [31.5%] versus 10 of 74 [13.5%], P = 0.0004), and patients with genotype B (17 of 43 [39.5%] versus 10 of 85 [11.8%], P = 0.004). On multivariate analysis, sustained disease remission (relative risk [RR] 3.00, 95% confidence interval [95% CI] 1.29-7.01, P = 0.01) and being 20-29 years old at initial liver biopsy (RR 2.94, 95% CI 1.01-8.62, P = 0.04) were independently associated with regression of fibrosis. The rate of fibrosis progression was lower in patients with sustained disease remission than in those who remained HBeAg positive (median 0 fibrosis units/year, range -2.00 to -0.70 fibrosis units/year, versus median 0.51 fibrosis units/year, range 0 to +2.03 fibrosis units/year, P = 0.02). CONCLUSION: Spontaneous sustained remission of disease is associated not only with little progression of fibrosis but also with regression of fibrosis.