Iris Ws Li

Convalescent Plasma Treatment Reduced Mortality in Patients With Severe Pandemic Influenza A (H1N1) 2009 Virus Infection

Treatment of severe pandemic influenza A(H1N1) 2009 virus infection with convalescent plasma suppressed the viral load and cytokine response, thereby reducing the subsequent risk of complication and death. Further studies by double-blind randomized controlled trial of plasma treatment in these patients are warranted.

Differential susceptibility of different cell lines to swine-origin influenza A H1N1, seasonal human influenza A H1N1, and avian influenza A H5N1 viruses

BACKGROUND The novel swine-origin influenza A H1N1 virus (S-OIV) causes the current pandemic. Its tissue tropism and replication in different cell lines are not well understood. OBJECTIVE Compare the growth characteristics of cell lines infected by S-OIV, seasonal influenza A H1N1 (sH1N1) and avian influenza A H5N1 (H5N1) viruses and the effect of temperature on viral replication. STUDY DESIGN Cytopathic effect (CPE), antigen expression by immunofluorescence (IF) and viral load profile by quantitative RT-PCR in 17 cell lines infected by S-OIV, sH1N1 and H5N1 were examined. Comparison of their replication efficiency in chick embryo was performed. The effect of temperature on viral replication in Madin-Darby canine kidney (MDCK) cells was determined by TCID(50) at 33 degrees C, 37 degrees C and 39 degrees C for 5 consecutive days. RESULTS S-OIV replicated in cell lines derived from different tissues or organs and host species with comparable viral load to sH1N1. Among 13 human cell lines tested, Caco-2 has the highest viral load for S-OIV. S-OIV showed a low viral load with no CPE or antigen expression in pig kidney cell PK-15, H5N1 demonstrated the most diverse cell tropism by CPE and antigen expression, and the highest viral replication efficiency in both cell lines and allantoic fluid. All three viruses demonstrated best growth at 37 degrees C in MDCK cells. CONCLUSION Cell line growth characteristics of S-OIV, sH1N1 and H5N1 appear to correlate clinically and pathologically with involved anatomical sites and severity. Low replication of S-OIV in PK-15 suggests that this virus is more adapted to human than swine.

Prevention of nosocomial transmission of swine-origin pandemic influenza virus A/H1N1 by infection control bundle

Summary After the outbreak of severe acute respiratory syndrome in Hong Kong, the importance of preventing nosocomial transmission of respiratory viruses has become a top priority in infection control. During the containment and early mitigation phases of the swine-origin influenza virus (S-OIV) A H1N1 pandemic, an infection control bundle consisting of multiple coherent measures was organised by our infection control team to minimise nosocomial transmission. This included repeated open staff forum achieving high attendance; early recognition of index cases among inpatients by liberal testing; early relief of sick staff from work; directly observed hand hygiene practice during outbreaks; and monitoring of compliance with infection control practice. During the first 100 days (from 1 May to 8 August 2009) when the first 100 laboratory-confirmed patients with S-OIV and 12 infected healthcare workers (HCWs) were identified, a total of 836 asymptomatic exposed persons (184 patients and 652 HCWs) were required to undergo a seven-day medical surveillance. The infection control nurses monitored them for the onset of symptoms. Four (0.48%) exposed persons (one house officer, two non-clinical staff, and one patient) were virologically confirmed with S-OIV. Not wearing a surgical mask either by the exposed persons during contact with the index cases (4/4 vs 264/832, P =0.010) or vice versa (4/4 vs 300/832, P =0.017, Fishers exact test) were found to be significant risk factors for nosocomial acquisition of S-OIV.

Sequential introduction of single room isolation and hand hygiene campaign in the control of methicillin-resistant Staphylococcus aureus in intensive care unit

BackgroundAfter renovation of the adult intensive care unit (ICU) with installation of ten single rooms, an enhanced infection control program was conducted to control the spread of methicillin-resistant Staphylococcus aureus (MRSA) in our hospital.MethodsSince the ICU renovation, all patients colonized or infected with MRSA were nursed in single rooms with contact precautions. The incidence of MRSA infection in the ICU was monitored during 3 different phases: the baseline period (phase 1); after ICU renovation (phase 2) and after implementation of a hand hygiene campaign with alcohol-based hand rub (phase 3). Patients infected with extended spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella species were chosen as controls because they were managed in open cubicles with standard precautions.ResultsWithout a major change in bed occupancy rate, nursing workforce, or the protocol of environmental cleansing throughout the study period, a stepwise reduction in ICU onset nonbacteraemic MRSA infection was observed: from 3.54 (phase 1) to 2.26 (phase 2, p = 0.042) and 1.02 (phase 3, p = 0.006) per 1000-patient-days. ICU onset bacteraemic MRSA infection was significantly reduced from 1.94 (phase 1) to 0.9 (phase 2, p = 0.005) and 0.28 (phase 3, p = 0.021) per 1000-patient-days. Infection due to ESBL-producing organisms did not show a corresponding reduction. The usage density of broad-spectrum antibiotics and fluoroquinolones increased from phase 1 to 3. However a significant trend improvement of ICU onset MRSA infection by segmented regression analysis can only be demonstrated when comparison was made before and after the severe acute respiratory syndrome (SARS) epidemic. This suggests that the deaths of fellow healthcare workers from an occupational acquired infection had an overwhelming effect on their compliance with infection control measures.ConclusionProvision of single room isolation facilities and promotion of hand hygiene practice are important. However compliance with infection control measures relies largely on a personal commitment, which may increase when personal safety is threatened.

Antimicrobial stewardship program directed at broad-spectrum intravenous antibiotics prescription in a tertiary hospital.

The antimicrobial stewardship program (ASP) is a major strategy to combat antimicrobial resistance and to limit its expenditure. We have improved on our existing ASP to implement a sustainable and cost-effective two-stage immediate concurrent feedback (ICF) model, in which the antimicrobial prescription is audited by two part-time infection control nurses at the first stage, followed by “physician ICF” at the second stage. In January 2005, an ASP focused on broad-spectrum intravenous antibiotics was implemented. All in-patients, except from the intensive care, bone marrow transplantation, liver transplantation, pediatric, and private units, being treated with broad-spectrum intravenous antibiotics were included. The compliance to ICF and “physician ICF”, antibiotics usage density measured by expenditure and defined daily doses (DDD) were recorded and analyzed before and after the ASP. The overall conformance rate to antibiotic prescription guidelines was 79.4%, while the conformance to ICF was 83.8%. Antibiotics consumption reduced from 73.06 (baseline, year 2004) to 64.01 (year 2007) per 1,000 patient bed-day-occupancy. Our model can be easily applied even in the clinical setting of limited resources.

Clinical and Virological Factors Associated with Viremia in Pandemic Influenza A/H1N1/2009 Virus Infection

Background Positive detection of viral RNA in blood and other non-respiratory specimens occurs in severe human influenza A/H5N1 viral infection but is not known to occur commonly in seasonal human influenza infection. Recently, viral RNA was detected in the blood of patients suffering from severe pandemic influenza A/H1N1/2009 viral infection, although the significance of viremia had not been previously studied. Our study aims to explore the clinical and virological factors associated with pandemic influenza A/H1N1/2009 viremia and to determine its clinical significance. Methodology/Principal Findings Clinical data of patients admitted to hospitals in Hong Kong between May 2009 and April 2010 and tested positive for pandemic influenza A/H1N1/2009 was collected. Viral RNA was detected by reverse-transcription polymerase chain reactions (RT-PCR) targeting the matrix (M) and HA genes of pandemic influenza A/H1N1/2009 virus from the following specimens: nasopharyngeal aspirate (NPA), endotracheal aspirate (ETA), blood, stool and rectal swab. Stool and/ or rectal swab was obtained only if the patient complained of any gastrointestinal symptoms. A total of 139 patients were included in the study, with viral RNA being detected in the blood of 14 patients by RT-PCR. The occurrence of viremia was strongly associated with a severe clinical presentation and a higher mortality rate, although the latter association was not statistically significant. D222G/N quasispecies were observed in 90% of the blood samples. Conclusion Presence of pandemic influenza A/H1N1/2009 viremia is an indicator of disease severity and strongly associated with D222G/N mutation in the viral hemagglutinin protein.

Effect of antibiotics on the bacterial load of meticillin-resistant Staphylococcus aureus colonisation in anterior nares

Prevalence of hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) infection or colonisation has been associated with antimicrobial consumption. The impact of antibiotic treatment on nasal colonisation is unknown. We conducted a three-month prospective study of 116 patients with extranasal MRSA infection or colonisation, whose nasal MRSA bacterial loads were determined during and after various antibiotic courses over a period of three weeks. Environmental swabs were also taken from the near patient environment. Concomitant nasal MRSA carriage was observed in 76.7% of extranasal MRSA-colonised or -infected patients. The median nasal MRSA bacterial load increased significantly from 2.78 (range 0-6.15) to 5.30 (range 2.90-8.41) log(10) cfu per swab (cfu/swab) (P<0.001) over 21 days during beta-lactam therapy. It also increased from 0 (range 0-4.00) to 4.30 (range 0-7.46) log(10)cfu/swab (P=0.039) over 14 days during fluoroquinolone therapy. Median bacterial loads were significantly higher for beta-lactam- and fluoroquinolone-treated patients on day 7 [4.78, range 0-7.30], day 14 [4.30, range 0-7.60] and day 21 [5.30, range 2.90-8.41] than controls not receiving antibiotics (P<0.05). These loads then decreased by 2-5log(10)cfu/swab 2 weeks after discontinuation of antibiotics. The environment of patients receiving beta-lactam agents (relative risk: 3.55; 95% confidence interval: 1.30-9.62; P=0.018) or fluoroquinolones (4.32; 1.52-12.31; P=0.008) demonstrated more MRSA contamination than the environment around control patients (0.79; 0.67-0.93; P=0.002). Patients on beta-lactam or fluoroquinolone therapy have increased incidence of MRSA colonisation and higher nasal bacterial loads, and appear to spread their MRSA into the near patient environment.

Prevention of nosocomial transmission of norovirus by strategic infection control measures.

BACKGROUND Nosocomial outbreaks of norovirus infection pose a great challenge to the infection control team. METHODS Between November 1, 2009, and February 28, 2010, strategic infection control measures were implemented in a hospital network. In addition to timely staff education and promotion of directly observed hand hygiene, reverse-transcription polymerase chain reaction for norovirus was performed as an added test by the microbiology laboratory for all fecal specimens irrespective of the request for testing. Laboratory-confirmed cases were followed up by the infection control team for timely intervention. The incidence of hospital-acquired norovirus infection per 1,000 potentially infectious patient-days was compared with the corresponding period in the preceding 12 months, and the incidence in the other 6 hospital networks in Hong Kong was chosen as the concurrent control. Phylogenetic analysis of norovirus isolates was performed. RESULTS Of the 988 patients who were tested, 242 (25%) were positive for norovirus; 114 (47%) of those 242 patients had norovirus detected by our added test. Compared with the corresponding period in the preceding 12 months, the incidence of hospital-acquired norovirus infection decreased from 131 to 16 cases per 1,000 potentially infectious patient-days (P < .001), although the number of hospital-acquired infections was low in both the study period (n = 8) and the historical control periods (n = 11). The incidence of hospital-acquired norovirus infection in our hospital network (0.03 cases per 1,000 patient-days) was significantly lower than that of the concurrent control (0.06 cases per 1,000 patient-days) (P = .015). Forty-three (93%) of 46 norovirus isolates sequenced belonged to the genogroup II.4 variant. CONCLUSIONS Strategic infection control measures with an added test may be useful in controlling nosocomial transmission of norovirus.

Successful control of vancomycin-resistant Enterococcus faecium outbreak in a neurosurgical unit at non-endemic region

Vancomycin-resistant enterococci (VRE) have emerged in many parts of the world, but have only been reported sporadically in Hong Kong. We report an outbreak of vancomycin-resistant Enterococcus faecium (VREfm) in a neurosurgical unit at a tertiary teaching hospital between 3 March and 3 April 2009 in Hong Kong. During the outbreak investigation, clinical samples from 193 (91.5%) of 211 patients who had stayed in the neurosurgical unit and 506 environmental samples were screened for VREfm. Besides the index case, another 3 (1.6%) out of 192 patients were found to be positive for VREfm. Two (0.4%) out of 506 environmental samples were positive for VREfm. All four clinical and two environmental isolates were found to be clonally related by pulse-field gel electrophoresis. The risk factors for nosocomial acquisition of VREfm included advanced age (P=0.047), presence of nasogastric tubing (P=0.002) and tracheostomy (P<0.001), and the use of β-lactam antibiotics (P<0.001) and vancomycin (P=0.001). Contrary to other VRE outbreaks in which the spread was rapid, the neurosurgical patients’ immobilization because of coma and mechanical ventilation dependency, and the vigilant practice of hand hygiene by health-care workers successfully limited the number of secondary cases despite the delayed recognition of the index case. All patients with VREfm were labeled in the hospital network information system so that stringent infection control measures with contact precautions would be carried out once these patients were readmitted to prevent its spread in our locality.

Fatal empyema thoracis caused by Schizophyllum commune with cross-reactive cryptococcal antigenemia.

ABSTRACT We report a fatal case of Schizophyllum commune empyema thoracis with cross-reactive cryptococcal antigenemia. In vitro testing confirmed the ability of the fungus to cause a positive cryptococcal antigen latex agglutination system (CALAS) test result. Such a result may lead to delay in diagnosis and treatment, as most strains of S. commune are resistant to fluconazole.