The epidemiology and transmission of methicillin-resistant Staphylococcus aureus in the community in Singapore: study protocol for a longitudinal household study

BACKGROUND/AIM

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common multidrug-resistant organisms in healthcare settings worldwide, but little is known about MRSA transmission outside of acute healthcare settings especially in Asia. We describe the methods for a prospective longitudinal study of MRSA prevalence and transmission.

METHODS

MRSA-colonized individuals were identified from MRSA admission screening at two tertiary hospitals and recruited together with their household contacts. Participants submitted self-collected nasal, axilla and groin (NAG) swabs by mail for MRSA culture at baseline and monthly thereafter for 6 months. A comparison group of households of MRSA-negative patients provided swab samples at one time point. In a validation sub-study, separate swabs from each site were collected from randomly selected individuals, to compare MRSA detection rates between swab sites, and between samples collected by participants versus those collected by trained research staff. Information on each participant's demographic information, medical status and medical history, past healthcare facilities usage and contacts, and personal interactions with others were collected using a self-administered questionnaire.

DISCUSSION/CONCLUSION

Understanding the dynamics of MRSA persistence and transmission in the community is crucial to devising and evaluating successful MRSA control strategies. Close contact with MRSA colonized patients may to be important for MRSA persistence in the community; evidence from this study on the extent of community MRSA could inform the development of household- or community-based interventions to reduce MRSA colonization of close contacts and subsequent re-introduction of MRSA into healthcare settings. Analysis of longitudinal data using whole-genome sequencing will yield further information regarding MRSA transmission within households, with significant implications for MRSA infection control outside acute hospital settings.

Prophylactic platelet transfusion plus supportive care versus supportive care alone in adults with dengue and thrombocytopenia: a multicentre, open-label, randomised, superiority trial

BACKGROUND

Dengue is the commonest vector-borne infection worldwide. It is often associated with thrombocytopenia, and prophylactic platelet transfusion is widely used despite the dearth of robust evidence. We aimed to assess the efficacy and safety of prophylactic platelet transfusion in the prevention of bleeding in adults with dengue and thrombocytopenia.

METHODS

We did an open-label, randomised, superiority trial in five hospitals in Singapore and Malaysia. We recruited patients aged at least 21 years who had laboratory-confirmed dengue (confirmed or probable) and thrombocytopenia (≤20 000 platelets per μL), without persistent mild bleeding or any severe bleeding. Patients were assigned (1:1), with randomly permuted block sizes of four or six and stratified by centre, to receive prophylactic platelet transfusion in addition to supportive care (transfusion group) or supportive care alone (control group). In the transfusion group, 4 units of pooled platelets were given each day when platelet count was 20 000 per μL or lower; supportive care consisted of bed rest, fluid therapy, and fever and pain medications. The primary endpoint was clinical bleeding (excluding petechiae) by study day 7 or hospital discharge (whichever was earlier), analysed by intention to treat. Safety outcomes were analysed according to the actual treatment received. This study was registered with ClinicalTrials.gov, number NCT01030211, and is completed.

FINDINGS

Between April 29, 2010, and Dec 9, 2014, we randomly assigned 372 patients to the transfusion group (n=188) or the control group (n=184). The intention-to-treat analysis included 187 patients in the transfusion group (one patient was withdrawn immediately) and 182 in the control group (one was withdrawn immediately and one did not have confirmed or probable dengue). Clinical bleeding by day 7 or hospital discharge occurred in 40 (21%) patients in the transfusion group and 48 (26%) patients in the control group (risk difference -4·98% [95% CI -15·08 to 5·34]; relative risk 0·81 [95% CI 0·56 to 1·17]; p=0·16). 13 adverse events occurred in the transfusion group and two occurred in the control group (5·81% [-4·42 to 16·01]; 6·26 [1·43 to 27·34]; p=0·0064). Adverse events that were possibly, probably, or definitely related to transfusion included three cases of urticaria, one maculopapular rash, one pruritus, and one chest pain, as well as one case each of anaphylaxis, transfusion-related acute lung injury, and fluid overload that resulted in serious adverse events. No death was reported.

INTERPRETATION

In adult patients with dengue and thrombocytopenia, prophylactic platelet transfusion was not superior to supportive care in preventing bleeding, and might be associated with adverse events.

FUNDING

National Medical Research Council, Singapore.

Aminoglycoside-associated acute kidney injury in elderly patients with and without shock

OBJECTIVES

Multiresistant Gram-negative pathogens pose major healthcare concerns with a limited therapeutic armamentarium. Aminoglycosides (AG) are under-utilized due to nephrotoxicity. We aimed to evaluate AG-associated acute kidney injury (AG-AKI) in elderly inpatients, with and without shock.

METHODS

We examined the incidence and predictors of AG-AKI by KDIGO criteria and extended renal dysfunction (ERD) in patients aged >60 years. ERD represented a composite of hospital mortality or absence of renal recovery over 6 months following AG-AKI.

RESULTS

Two hundred and seventy-eight patients (aged 74 ± 8 years) were studied; 43% and 19% received >7 and >10 days of AG therapy, respectively, and 70% gentamicin (versus amikacin). Thirteen per cent had shock and 17% developed AG-AKI. Comparing all patients with shock versus no shock, AG-AKI developed in 33% versus 14%, respectively (P = 0.005); correspondingly among 47 patients with AG-AKI, more with shock had stage 2/3 AKI (92% versus 43%) and dialysis (50% versus 9%) (P < 0.01), but more had other strong AKI confounders than AG therapy alone (83% versus 40%, P = 0.02). Multivariate analyses identified mechanical ventilation, frusemide administration and AG therapy >10 days as predictors of AG-AKI (P < 0.05), whereas shock, pneumonia and frusemide administration predicted more severe stage 2/3 AG-AKI (P < 0.05). Hospital mortality was 30% versus 7% with AG-AKI versus none (P < 0.001). Twenty-three of 211 (11%) patients with extended analysis had ERD, with 47% experiencing renal recovery following AG-AKI. Mechanical ventilation and contrast administration during index hospitalization predicted ERD (P < 0.05).

CONCLUSIONS

AG-AKI is common in the elderly, with a significant risk of ERD, but the cause and severity are greatly influenced by critical illness and shock, more so than AG therapy alone.

Empiric Piperacillin-Tazobactam versus Carbapenems in the Treatment of Bacteraemia Due to Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are a common cause of bacteraemia in endemic countries and may be associated with high mortality; carbapenems are considered the drug of choice. Limited data suggest piperacillin-tazobactam could be equally effective. We aimed to compare 30-day mortality of patients treated empirically with piperacillin-tazobactam versus a carbapenem in a multi-centre retrospective cohort study in Singapore. Only patients with active empiric monotherapy with piperacillin-tazobactam or a carbapenem were included. A propensity score for empiric carbapenem therapy was derived and an adjusted multivariate analysis of mortality was conducted. A total of 394 patients had ESBL-Escherichia.coli and ESBL-Klebsiella pneumoniae bacteraemia of which 23.1% were community acquired cases. One hundred and fifty-one received initial active monotherapy comprising piperacillin-tazobactam (n = 94) or a carbapenem (n = 57). Patients who received carbapenems were less likely to have health-care associated risk factors and have an unknown source of bacteraemia, but were more likely to have a urinary source. Thirty-day mortality was comparable between those who received empiric piperacillin-tazobactam and a carbapenem (29 [30.9%] vs. 17 [29.8%]), P = 0.89). Those who received empiric piperacillin-tazobactam had a lower 30-day acquisition of multi-drug resistant and fungal infections (7 [7.4%] vs. 14 [24.6%]), P<0.01). After adjusting for confounders, use of empiric piperacillin-tazobactam was not associated with increased 30-day mortality (OR 1.00, 95% CI; 0.45–2.17). Empiric piperacillin-tazobactam was not associated with increased 30-day mortality and may result in fewer multi-drug resistant and fungal infections when compared with a carbapenem.

Use of erythrocyte sedimentation rate and C-reactive protein to predict osteomyelitis recurrence

PURPOSE

To determine the association between both erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and osteomyelitis recurrence.

METHODS

Records of 81 males and 27 females aged 10 to 87 (median, 54) years who underwent antibiotic/ surgical treatment for primary (n=68) or recurrent (n=40) osteomyelitis that was related (n=26) or unrelated (n=82) to a prosthesis were reviewed. Of the 40 cases of osteomyelitis recurrence followed up for a median of 23.4 (range, 0.6-74.0) months, 7 and 33 were related and unrelated to a prosthesis, respectively. The cutoff points of lowest ESR and CRP for osteomyelitis recurrence were calculated. Risk factors for osteomyelitis recurrence were determined.

RESULTS

Osteomyelitis recurrence was associated with diabetes mellitus, ischaemic heart disease, non-healing wound, infection in the lower limb, and infection with methicillin-resistant Staphylococcus aureus. The cutoff points of CRP ≥5 mg/l and ESR ≥20 mm/h were used for osteomyelitis recurrence. Risk factors for osteomyelitis recurrence were ESR ≥20 mm/h, infection with methicillin-resistant S aureus, and infection in the lower limb.

CONCLUSION

ESR was more sensitive, specific, and independently associated with osteomyelitis recurrence and should be used to guide the duration of antibiotic treatment.

The emerging threat of multidrug-resistant Gram-negative bacteria in urology

Antibiotic resistance in Gram-negative uropathogens is a major global concern. Worldwide, the prevalence of Enterobacteriaceae that produce extended-spectrum β-lactamase or carbapenemase enzymes continues to increase at alarming rates. Likewise, resistance to other antimicrobial agents including aminoglycosides, sulphonamides and fluoroquinolones is also escalating rapidly. Bacterial resistance has major implications for urological practice, particularly in relation to catheter-associated urinary tract infections (UTIs) and infectious complications following transrectal-ultrasonography-guided biopsy of the prostate or urological surgery. Although some new drugs with activity against Gram-negative bacteria with highly resistant phenotypes will become available in the near future, the existence of a single agent with activity against the great diversity of resistance is unlikely. Responding to the challenges of Gram-negative resistance will require a multifaceted approach including considered use of current antimicrobial agents, improved diagnostics (including the rapid detection of resistance) and surveillance, better adherence to basic measures of infection prevention, development of new antibiotics and research into non-antibiotic treatment and preventive strategies.

microRNA expression in blood of dengue patients

BACKGROUND

Dengue is the most common arboviral illness worldwide. While most infected patients recover, a proportion of them develop severe complications or fatality. Nevertheless, the pathophysiological mechanisms which distinguish the disease severity and associated complications are not clearly understood. We studied blood profiles of dengue patients in order to identify microRNAs that could play a role in these pathophysiological mechanisms.

METHODS

Blood samples from 26 dengue-infected patients were collected within 0-14 days of infection. Together with samples obtained from six healthy individuals, microRNA profiles were generated to identify significantly altered microRNAs upon dengue infection. Profiles of patients with influenza were also used to determine the disease specificity of these altered microRNAs. Their discriminative power to distinguish dengue from influenza was then tested statistically.

RESULTS

Several significantly altered microRNAs were identified in patients with dengue. Twelve microRNAs were specifically altered upon acute dengue whereas 14 microRNAs exhibited similar expression between dengue and influenza. Seventeen microRNAs which could potentially distinguish dengue-related complications were also identified. Expression of miR-24-1-5p, miR-512-5p and miR-4640-3p distinguished mild dengue from those exhibiting liver complications whereas miR-383 was significantly upregulated in mild dengue compared to those diagnosed as severe dengue with fluid accumulation.

CONCLUSIONS

We identified two panels of microRNAs - one specific for dengue and the other common to dengue and influenza. We also report on the differentially expressed microRNAs in patients with mild versus severe dengue, which could be the basis for the complications seen in them.

Preparedness of institutions around the world for managing patients with Ebola virus disease: an infection control readiness checklist

BACKGROUND

In response to global concerns about the largest Ebola virus disease (EVD), outbreak to-date in West Africa documented healthcare associated transmission and the risk of global spread, the International Society of Chemotherapy (ISC) Infection Control Working Group created an Ebola Infection Control Readiness Checklist to assess the preparedness of institutions around the globe. We report data from the electronic checklist that was disseminated to medical professionals from October to December 2014 and identify action needed towards better preparedness levels.

FINDINGS

Data from 192 medical professionals (one third from Africa) representing 125 hospitals in 45 countries around the globe were obtained through a specifically developed electronic survey. The survey contained 76 specific questions in 7 major sections: Administrative/operational support; Communications; Education and audit; Human resources, Supplies, Infection Prevention and Control practices and Clinical management of patients. The majority of respondents were infectious disease specialists/infection control consultants/clinical microbiologists (75; 39 %), followed by infection control professionals (59; 31 %) and medical doctors of other specialties (17; 9 %). Nearly all (149; 92 %) were directly involved in Ebola preparedness activities. Whilst, 54 % indicated that their hospital would need to handle suspected and proven Ebola cases, the others would subsequently transfer suspected cases to a specialized centre.

CONCLUSION

The results from our survey reveal that the general preparedness levels for management of potentially suspected cases of Ebola virus disease is only partially adequate in hospitals. Hospitals designated for admitting EVD suspected and proven patients had more frequently implemented Infection Control preparedness activities than hospitals that would subsequently transfer potential EVD cases to other centres. Results from this first international survey provide a framework for future efforts to improve hospital preparedness worldwide.

Comparable outcomes for β-lactam/β-lactamase inhibitor combinations and carbapenems in definitive treatment of bloodstream infections caused by cefotaxime-resistant Escherichia coli or Klebsiella pneumoniae

BACKGROUND

Extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae are often susceptible in vitro to β-lactam/β-lactamase inhibitor (BLBLI) combination antibiotics, but their use has been limited by concerns of clinical inefficacy. We aimed to compare outcomes between patients treated with BLBLIs and carbapenems for bloodstream infection (BSI) caused by cefotaxime non-susceptible (likely ESBL- or AmpC β-lactamase-producing) Escherichia coli and Klebsiella pneumoniae.

METHODS

All adult patients with a BSI caused by cefotaxime non-susceptible E. coli or K. pneumoniae were included from May 2012-May 2013. We compared outcomes between patients who had definitive monotherapy with a carbapenem to those who had definitive monotherapy with a BLBLI.

RESULTS

There were 92 BSIs that fulfilled the microbiological inclusion criteria. 79 (85.9%) were caused by E. coli and 13 (14.1%) by K. pneumoniae. Four out of 23 (17.4%) patients treated with carbapenem monotherapy and 2 out of 24 (8.3%) patients treated with BLBLI monotherapy died (adjusted HR for survival 0.91, 95% CI 0.13 to 6.28; p = 0.92). The time to resolution of systemic inflammatory response syndrome (SIRS) criteria did not vary between the treatment groups (adjusted HR 0.91, 95% CI 0.32 to 2.59; p = 0.97). The length of hospital admission post-positive blood culture was slightly longer in patients treated with BLBLIs (median duration 15 vs. 11 days), although this was not significant (adjusted HR 0.62; 95% CI 0.27 to 1.42; p = 0.26). There were no significant differences in subsequent isolation of carbapenem resistant organisms (4.3% vs. 4.2%, p = 1.0), C. difficile infection (13.0% vs. 8.3%, p = 0.67) or relapsed BSI (0% vs. 2%, p = 0.23).

CONCLUSIONS

BLBLIs appear to have a similar efficacy to carbapenems in the treatment of cefotaxime-resistant E. coli and K. pneumoniae bloodstream infections. Directed therapy with a BLBLI, when susceptibility is proven, may represent an appropriate carbapenem-sparing option.

Debate on MERS-CoV respiratory precautions: surgical mask or N95 respirators?

Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in mid-2012, there has been controversy over the respiratory precaution recommendations in different guidelines from various international bodies. Our understanding of MERS-CoV is still evolving. Current recommendations on infection control practices are heavily influenced by the lessons learnt from severe acute respiratory syndrome. A debate on respiratory precautions for MERS-CoV was organised by Infection Control Association (Singapore) and the Society of Infectious Disease (Singapore). We herein discuss and present the evidence for surgical masks for the protection of healthcare workers from MERS-CoV.

Bitten by a bug or a bag? Transfusion-transmitted dengue: a rare complication in the bleeding surgical patient

BACKGROUND

Blood-borne infections remain a risk of blood transfusions. While routine screening of donated blood products has greatly reduced the risk of human immunodeficiency virus, hepatitis B, and hepatitis C transmission, arboviruses such as dengue, chikungunya, and the West Nile virus remain significant risks especially during outbreaks.

CASE REPORT

We report a rare case of dengue documented to be acquired through a blood transfusion, which resulted in severe thrombocytopenia prolonging admission in hospital in a neurosurgical patient.

RESULTS

The donor of one of the units of red blood cells presented with dengue fever 2 days after donating. Sanger sequencing confirmed DENV-2 (dengue virus, Serotype 2) in both the donor and the patient samples and showed 100% nucleotide sequence identity between the two viruses, confirming transfusion-transmitted dengue infection.

CONCLUSION

This case highlights the importance of arboviral screening of donor blood, especially for populations in endemic areas during outbreaks.

Predictors of In-hospital Adverse Events in Patients with Prosthetic Valve Infective Endocarditis

BACKGROUND

We aimed to study patients with prosthetic valve endocarditis (PVE) and analyse factors associated with in-hospital adverse events.

METHODS

A review of all patients who underwent echocardiography at a local university hospital with definite PVE (modified Duke's criteria) was performed. Adverse events of in-hospital mortality and redo valve surgery were identified.

RESULTS

There were 23 patients with PVE (median age 53 years (IQR:38-66), 12 males (52%)). Twelve adverse events occurred including seven (30%) in-hospital mortalities and five (21%) redo valve surgery. Factors associated with in-hospital mortality include Staphylococcus aureus-PVE (86% vs 31%, p=0.027), presence of shock (86% vs 19%, p=0.005) and intensive care unit admission (72% vs 19%, p=0.026). Factors associated with the need for redo valve surgery include a younger median age (37 vs 61 years, p=0.012), longer median length of stay (58 vs 17 days, p=0.004), history of intravenous drug abuse (IVDA) (60% vs 6%, p=0.021) and right-sided valvular involvement (40% vs 0%, p=0.040). Using a composite endpoint of both outcomes, factors associated with in-hospital adverse events were a history of IVDA (36% vs 0%, p=0.037) and presence of shock (64% vs 17%, p=0.036).

CONCLUSION

PVE carries a high risk of poor clinical outcome in terms of in-hospital mortality and the need for redo surgery.

Healthcare associated infections (HAI) perspectives

Healthcare associated infections (HAI) are among the major complications of modern medical therapy. The most important HAIs are those related to invasive devices: central line-associated bloodstream infections (CLABSI), catheter-associated urinary tract infections (CAUTI), ventilator-associated pneumonia (VAP) as well as surgical site infections (SSI). HAIs are associated with significant mortality, morbidities and increasing healthcare cost. The cited case-fatality rate ranges from 2.3% to 14.4% depending on the type of infection. In this mini-review, we shed light on these aspects as well as drivers to decrease HAIs.

Progression from new methicillin-resistant Staphylococcus aureus colonisation to infection: an observational study in a hospital cohort

BACKGROUND

Patients newly colonised with methicillin-resistant Staphylococcus aureus (MRSA) are at higher risk of clinical MRSA infection. At present, there are limited data on the duration or magnitude of this risk in a hospital population with a known time of MRSA acquisition.

METHODS

A retrospective cohort study of 909 adult patients known to have newly identified MRSA colonisation during admission to National University Hospital, Singapore between 1 July 2007 and 30 June 2011 was undertaken. Patients were excluded if they had history of previous MRSA colonisation or infection, or if they had been a hospital inpatient in the preceding 12 months. Data were collected on the development of MRSA infection requiring hospitalisation up to 30 June 2012.

RESULTS

Of 840 patients newly colonised with MRSA as identified on active surveillance and not clinical specimens, 546 were men (65.0%) and the median age was 65 years (range 18-103 years). Median follow up was 24 months (range 0 -64 months, 85.1% followed >6 months). Clinical infection occurred in 121 patients (14.4%) with median time to infection of 22 days (95% CI 14-31). Overall 71.9% (87/121) of infected patients developed infection within 60 days of the date MRSA colonisation was detected. However, 17/121 patients (14.0%) developed clinical infection more than six months after documented MRSA acquisition. The most common sites of clinical infection were skin and soft tissue (49/121, 40.5%, 95% CI 31.7-49.8), respiratory tract (37/121, 30.6%, 95% CI 22.5-39.6) and bone and joint infections (14/121, 11.6%, 95% CI 6.5-18.7). Thirteen patients (13/121, 10.7%, 95% CI 5.8-17.7) had bacteraemias, of which six (5.0% 95% CI 1.8-10.5) were primary and seven (5.7%, 95% CI 2.3-11.6) were secondary to infection at other sites. Crude mortality at 30 days and six months was higher in patients with MRSA infection than colonisation alone (aOR 5.49, 95% CI 2.75-10.95, p<0.001 and aOR 2.94, 95% CI 1.78-4.85, p<0.001 respectively).

CONCLUSION

Risk of clinical infection is highest soon after MRSA acquisition. Prevention of MRSA acquisition in hospital will have significant impact on morbidity and mortality for patients.

Sustained meticillin-resistant Staphylococcus aureus control in a hyper-endemic tertiary acute care hospital with infrastructure challenges in Singapore

Background

Meticillin-resistant Staphylococcus aureus (MRSA) has been entrenched in Singapore hospitals since the 1980s, with an excess of 600 non-duplicate cases of infections (120 bacteraemia episodes) each year in our 995-bed university hospital. Approximately 5% of our hospital beds are used as isolation facilities.

Aim

To study the impact of an MRSA control bundle that was implemented via gradual geographic extension across hospital wards.

Methods

The bundle included active surveillance on admission and transfer/discharge to identify ward-based acquisition of MRSA, isolation and cohorting of MRSA-infected patients, enhanced hand hygiene initiatives, and publicly displayed feedback of MRSA acquisition and hand hygiene compliance rates. Implementation was between October 2006 and June 2010 in order to provide lead-time for the incremental development of infrastructural capacity, and to develop an ethic of infection prevention among staff. Results were analysed via interrupted time-series analysis.

Findings

MRSA infections fell midway through the implementation, with MRSA bacteraemia declining from 0.26 [95% confidence interval (CI): 0.18–0.34] cases per 1000 inpatient-days in the first quarter of 2004 to 0.11 (95% CI: 0.07–0.19) cases per 1000 inpatient-days in the first quarter of 2012. MRSA acquisition rates fell a year after the programme had been fully implemented, whereas hand hygiene compliance rose significantly from 47% (95% CI: 44–49) in the first quarter of 2009 to 69% (95% CI: 68–71) in the first quarter of 2012.

Conclusion

Successful staged implementation of an MRSA bundle in a hyper-endemic setting is sustainable and represents a model that may be adapted for similar settings.

Inappropriate empirical antimicrobial therapy for multidrug-resistant organisms in critically ill patients with pneumonia is not an independent risk factor for mortality: Results of a prospective observational study of 758 patients

The benefits of broad-spectrum initial empirical antibiotic therapy for all patients in intensive care units (ICUs) with high rates of multidrug-resistant organisms (MDROs) have not been critically evaluated. In this study, 758 ICU patients with pneumonia were prospectively evaluated. Of 349 positive respiratory cultures, 119 (34.1%) were with MDRO isolates. These were associated with increased mortality [adjusted hazard ratio (HR)=1.65, 95% confidence interval (CI) 1.01-2.68; P=0.04] as was increasing age and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Among the patients with MDRO-associated pneumonia, increasing age, APACHE II score and inappropriate definitive antimicrobial therapy (IDAT) were found to be significant risk factors for mortality (in-ICU mortality, adjusted HR=2.8, 95% CI 1.3-5.8; P=0.007), but inappropriate empirical antimicrobial therapy (IEAT) was not (in-ICU mortality, unadjusted HR=1.6, 95% CI 0.7-3.6; P=0.3). In conclusion, we found that among critically ill patients with MDRO-associated pneumonia, IEAT is not an independent risk factor for ICU mortality. Hence, we do not recommend the use of broad-spectrum initial empirical antimicrobial therapy for all patients, as its benefits may not outweigh the potential risks. Early microbiological diagnosis to facilitate implementation of early definitive antimicrobial therapy through use of novel technologies is likely to have a major impact.

The global spread of healthcare-associated multidrug-resistant bacteria: a perspective from Asia

Since antibiotics were first used, each new introduced class has been followed by a global wave of emergent resistance, largely originating in Europe and North America where they were first used. Methicillin-resistant Staphylococcus aureus spread from the United Kingdom and North America across Europe and then Asia over more than a decade. Vancomycin-resistant enterococci and Klebsiella pneumoniae carbapenemase-producing K. pneumoniae followed a similar path some 20 years later. Recently however, metallo-β-lactamases have originated in Asia. New Delhi metallo-β-lactamase-1 was found in almost every continent within a year of its emergence in India. Metallo-β-lactamase enzymes are encoded on highly transmissible plasmids that spread rapidly between bacteria, rather than relying on clonal proliferation. Global air travel may have helped facilitate rapid dissemination. As the antibiotic pipeline offers little in the short term, our most important tools against the spread of antibiotic resistant organisms are intensified infection control, surveillance, and antimicrobial stewardship.

Combination therapy with amantadine, oseltamivir and ribavirin for influenza A infection: safety and pharmacokinetics

BACKGROUND

Antiviral resistance among influenza A viruses is associated with high morbidity and mortality in immunocompromised hosts. However, treatment strategies for drug-resistant influenza A are not established. A triple-combination antiviral drug (TCAD) regimen consisting of amantadine (AMT), oseltamivir (OSL) and ribavirin (RBV) demonstrated good efficacy in an animal model.

METHODS

We first analysed the pharmacokinetics (PKs) of TCAD therapy in healthy volunteers. We then performed a pilot study of TCAD therapy in patients undergoing chemotherapy or haematopoietic cell transplantation. AMT (75 mg), OSL (50 mg) and RBV (200 mg) were administered three times a day for 10 days. The safety and PKs of TCAD therapy were monitored.

RESULTS

The PKs of TCAD therapy in healthy volunteers was shown to be similar to the PKs of each drug individually from a single dose. In the pilot study, six immunocompromised patients received TCAD therapy and one patient received OSL monotherapy. All but one patient completed 10 days of TCAD therapy without side effects; one patient receiving TCAD was withdrawn from the study because of respiratory failure and ultimately recovered. Viral load was decreased after TCAD therapy, despite the presence of either AMT- or OSL-resistant virus in two cases. One patient with 2009 influenza A/H1N1 receiving OSL monotherapy developed confirmed OSL resistance during treatment.

CONCLUSIONS

TCAD therapy had similar PKs to each individual antiviral during monotherapy following a single dose and can be administered safely in immunocompromised patients.

Teacher led school-based surveillance can allow accurate tracking of emerging infectious diseases - evidence from serial cross-sectional surveys of febrile respiratory illness during the H1N1 2009 influenza pandemic in Singapore

BACKGROUND

Schools are important foci of influenza transmission and potential targets for surveillance and interventions. We compared several school-based influenza monitoring systems with clinic-based influenza-like illness (ILI) surveillance, and assessed the variation in illness rates between and within schools.

METHODS

During the initial wave of pandemic H1N1 (pdmH1N1) infections from June to Sept 2009 in Singapore, we collected data on nation-wide laboratory confirmed cases (Sch-LCC) and daily temperature monitoring (Sch-DTM), and teacher-led febrile respiratory illness reporting in 6 sentinel schools (Sch-FRI). Comparisons were made against age-stratified clinic-based influenza-like illness (ILI) data from 23 primary care clinics (GP-ILI) and proportions of ILI testing positive for pdmH1N1 (Lab-ILI) by computing the fraction of cumulative incidence occurring by epidemiological week 30 (when GP-ILI incidence peaked); and cumulative incidence rates between school-based indicators and sero-epidemiological pdmH1N1 incidence (estimated from changes in prevalence of A/California/7/2009 H1N1 hemagglutination inhibition titers ≥ 40 between pre-epidemic and post-epidemic sera). Variation in Sch-FRI rates in the 6 schools was also investigated through a Bayesian hierarchical model.

RESULTS

By week 30, for primary and secondary school children respectively, 63% and 79% of incidence for Sch-LCC had occurred, compared with 50% and 52% for GP-ILI data, and 48% and 53% for Sch-FRI. There were 1,187 notified cases and 7,588 episodes in the Sch-LCC and Sch-DTM systems; given school enrollment of 485,723 children, this represented 0.24 cases and 1.6 episodes per 100 children respectively. Mean Sch-FRI rate was 28.8 per 100 children (95% CI: 27.7 to 29.9) in the 6 schools. We estimate from serology that 41.8% (95% CI: 30.2% to 55.9%) of primary and 43.2% (95% CI: 28.2% to 60.8%) of secondary school-aged children were infected. Sch-FRI rates were similar across the 6 schools (23 to 34 episodes per 100 children), but there was widespread variation by classrooms; in the hierarchical model, omitting age and school effects was inconsequential but neglecting classroom level effects led to highly significant reductions in goodness of fit.

CONCLUSIONS

Epidemic curves from Sch-FRI were comparable to GP-ILI data, and Sch-FRI detected substantially more infections than Sch-LCC and Sch-DTM. Variability in classroom attack rates suggests localized class-room transmission.

Complex partial status epilepticus associated with adult H1N1 infection

In the wake of the worldwide H1N1 pandemic, there has been evidence that the H1N1 influenza virus is associated with neurological complications. This is the first report describing status epilepticus in an adult patient with H1N1 virus infection, to our knowledge. This patient had no prior history of epilepsy and presented with complex partial status epilepticus. This was further illustrated on electroencephalographs and MRI brain changes that corresponded with the patient's clinical state and which subsequently resolved on follow-up. Although uncommon, H1N1 infections may result in central nervous system complications in adults and it is crucial to treat such patients with urgency.

Influenza outbreaks in Singapore: epidemiology, diagnosis, treatment and prevention

With the recent influenza A/H1N1 2009 pandemic still spreading through global populations, there has been an increased focus on optimizing the prevention, diagnosis and treatment of influenza infections, as well as the epidemiology of the virus. Clinical and epidemiological data on influenza infections in tropical countries have been relatively sparse until fairly recently, and it is the aim of this review to close some of these gaps by examining the behavior of influenza viruses in the tropical Singaporean population.

Differences in the compliance with hospital infection control practices during the 2009 influenza H1N1 pandemic in three countries

BACKGROUND

In December 2009, the World Health Organization (WHO) issued updated guidelines on the prevention of H1N1 influenza virus in healthcare settings. In 2010, the WHO pandemic influenza alert level was still at phase 6.

AIM

To study the practice of infection control measures during the 2009 influenza H1N1 pandemic among healthcare workers (HCWs) in three countries.

METHODS

A standardized, self-administered anonymous questionnaire survey was conducted in 2010 among doctors, nurses and allied HCWs in 120 hospital-based clinical departments in Hong Kong, Singapore and the UK. Questions were asked on demographics; previous experience and perceived severity of influenza; infection control practices; uptake of seasonal influenza vaccination and H1N1 vaccination. Multiple logistic regression was used to test the independent association with different factors.

FINDINGS

A total of 2100 HCWs in the three countries participated. They reported high compliance (>80%) with infection control procedures regarded as standard for droplet-transmitted infections including wearing and changing gloves, and washing hands before and after patient contact. However, the reported use of masks with indirect or direct patient contact (surgical or N95 as required by their hospital) varied considerably (96.4% and 70.4% for Hong Kong; 82.3% and 87.7% for Singapore; 25.3% and 62.0% for the UK). Reported compliance was associated with job title, number of patient contacts and perceived severity of pandemics. There was no association between the uptake for seasonal or 2009 H1N1 vaccines and compliance.

CONCLUSIONS

Compliance with infection control measures for pandemic influenza appears to vary widely depending on the setting.

Infectious disease trends among immunocompromised hosts

With our rapidly ageing population and advancing treatments for patients with haematological, oncologic and rheumatological diseases, there are increasing numbers of immunocompromised patients presenting to primary care and general hospitals with opportunistic infections. This review considers the trends of these infections across four representative subgroups: fungal infections following haematopoietic stem cell transplant; viral infections post solid organ transplant; mycobacterial infections during treatment with targeted biological agents; and bacterial infections as a cause of fever in neutropenia. We also consider the impact of host, pathogens, environments and treatments on the epidemiology and outcomes of these infections.

Effectiveness of pandemic H1N1-2009 vaccination in reducing laboratory confirmed influenza infections among military recruits in tropical Singapore

Background

Limited information is available about pandemic H1N1-2009 influenza vaccine effectiveness in tropical communities. We studied the effectiveness of a pandemic H1N1 vaccination program in reducing influenza cases in Singapore.

Methods

A surveillance study was conducted among military personnel presenting with febrile respiratory illness from mid-2009 to mid-2010. Consenting individuals underwent nasal washes, which were tested with RT-PCR and subtyped. A vaccination program (inactivated monovalent Panvax H1N1-2009 vaccine) was carried out among recruits. A Bayesian hierarchical model was used to quantify relative risks in the pre- and post-vaccination periods. An autoregressive generalised linear model (GLM) was developed to minimise confounding.

Results

Of 2858 participants, 437(15.3%), 60(2.1%), and 273(9.6%) had pandemic H1N1, H3N2, and influenza B. The ratio of relative risks for pandemic H1N1 infection before and after vaccination for the recruit camp relative to other camps was 0.14(0.016,0.49); for H3N2, 0.44(0.035,1.8); and for influenza B, 18(0.77,89). Using the GLM for the recruit camp, post-vaccination weekly cases decreased by 54%(37%,67%, p<0.001) from that expected without vaccination; influenza B increased by 66 times(9–479 times, p<0.001); with no statistical difference for H3N2 (p = 0.54).

Conclusions

Pandemic vaccination reduced H1N1-2009 disease burden among military recruits. Routine seasonal influenza vaccination should be considered.

Hand hygiene and infection control survey pre- and peri-H1N1-2009 pandemic: knowledge and perceptions of final year medical students in Singapore

INTRODUCTION

Infection control and hand hygiene are taught at different points in the undergraduate medical curriculum. We conducted a survey on fifth year medical (M5) students pre- and peri-influenza A (H1N1-2009) pandemic, attempting to ascertain whether the pandemic had affected their knowledge, perception and practice of hand hygiene and other aspects of infection control.

METHODS

A self-administered anonymous survey of M5 students was performed between August 2008 and February 2010, corresponding to two successive classes: M5-2008 (Class of 2004/09) and M5-2009 (Class of 2005/10). Completed survey forms were collated and analysed centrally.

RESULTS

There were 191 and 123 respondents for M5-2008 and M5-2009, respectively, corresponding to 74.9% and 47.3% of the respective classes. More M5-2009 respondents recognised alcohol hand rub as the preferred mode of hand hygiene practice and felt that there were insufficient isolation facilities in hospitals. Otherwise, survey responses were consistent. The majority felt that few doctors practiced hand hygiene appropriately, with the major obstructing factor being lack of time during ward rounds. The most important factor for improving hand hygiene compliance among junior doctors and students was for senior clinicians to lead by example. A significant minority believed that it was necessary to isolate patients with chikungunya, malaria or HIV.

CONCLUSION

The 2009 H1N1 pandemic made little impact on medical students' knowledge and practice of infection control. Nonetheless, their responses have suggested avenues for improving infection control practice, including persuading senior clinicians to lead by example in hand hygiene practice and addressing gaps in knowledge on patient isolation policies.

The clinical course of rapidly growing nontuberculous mycobacterial peritoneal dialysis infections in Asians: A case series and literature review

INTRODUCTION

Peritoneal dialysis (PD)-related infections due to rapidly growing nontuberculous mycobacterium (RGNTM) are rare in Asians and have variable clinical outcomes.

METHODS

We analysed retrospectively a series of RGNTM infections in a single-centre multi-ethnic Asian population over a 5-year period. Clinical features, treatment, risk factors and outcomes are discussed.

RESULTS

Ten infections are described. They constituted 3% of all culture-positive exit site infection (ESI) and PD peritonitis. Seventy percent were due to Mycobacterium abscessus (three ESI and four peritonitis). There were two Mycobacterim fortuitum and one Mycobacterium chelonei peritonitis. No specific findings differentiated RGNTM infections from those caused by traditional organisms. Six cases had received prior antibiotics, two being topical gentamicin. Initial routine culture and alcohol acid fast bacillus were negative except for one case of M. abscessus. A confirmatory diagnosis was made a median 9 days post culture. No infection responded to routine antibiotics. Antibiotic resistance was variable but M. abscessus was universally sensitive to clarithromycin. Combined antibiotics based on sensitivity profile were successfully used in 70% of the cases. PD catheter loss was 80%. Three-month mortality was 40% (vs. 8.5% and 12% in non-RGNTM ESI and peritonitis, respectively). This may be related to the cohort high mean Charlson score of 7.5.

CONCLUSION

RGNTM PD infections are commoner in Asians than previously reported. Their early diagnosis requires a high index of suspicion and appropriate treatment started promptly. They are associated with prior antibiotic use and refractory culture-negative infections, delayed diagnosis and lead to significant catheter loss and death.

Comparison of pandemic (H1N1) 2009 and seasonal influenza viral loads, Singapore

Mean viral loads for patients with pandemic (H1N1) 2009 were ≈1 log₁₀ times lower than those for patients with seasonal influenza within the first week after symptom onset. Neither pandemic nor seasonal influenza viral loads correlated with clinical severity of illness. No correlation was found between viral loads and concurrent illness.

A clinical diagnostic model for predicting influenza among young adult military personnel with febrile respiratory illness in Singapore

Introduction

Influenza infections present with wide-ranging clinical features. We aim to compare the differences in presentation between influenza and non-influenza cases among those with febrile respiratory illness (FRI) to determine predictors of influenza infection.

Methods

Personnel with FRI (defined as fever≥37.5°C, with cough or sore throat) were recruited from the sentinel surveillance system in the Singapore military. Nasal washes were collected, and tested using the Resplex II and additional PCR assays for etiological determination. Interviewer-administered questionnaires collected information on patient demographics and clinical features. Univariate comparison of the various parameters was conducted, with statistically significant parameters entered into a multivariate logistic regression model. The final multivariate model for influenza versus non-influenza cases was used to build a predictive probability clinical diagnostic model.

Results

821 out of 2858 subjects recruited from 11 May 2009 to 25 Jun 2010 had influenza, of which 434 (52.9%) had 2009 influenza A (H1N1), 58 (7.1%) seasonal influenza A (H3N2) and 269 (32.8%) influenza B. Influenza-positive cases were significantly more likely to present with running nose, chills and rigors, ocular symptoms and higher temperature, and less likely with sore throat, photophobia, injected pharynx, and nausea/vomiting. Our clinical diagnostic model had a sensitivity of 65% (95% CI: 58%, 72%), specificity of 69% (95% CI: 62%, 75%), and overall accuracy of 68% (95% CI: 64%, 71%), performing significantly better than conventional influenza-like illness (ILI) criteria.

Conclusions

Use of a clinical diagnostic model may help predict influenza better than the conventional ILI definition among young adults with FRI.

Overview/reflections on the 2009 H1N1 pandemic

The Influenza A H1N1 2009 pandemic was a test of the global public health response. Strategies that worked included mass vaccine production and antivirals while quarantine and isolation proved futile. Among the lessons learned was the importance of severity in the definition of a pandemic.

Value of team approach combined with clinical pathway for diabetic foot problems: a clinical evaluation

AIMS

To evaluate the effectiveness of management of diabetic foot problems (DFP) by the National University Hospital (NUH) Multidisciplinary Diabetic Foot Team combined with a clinical pathway in terms of average length of stay (ALOS), readmission rates, hospitalisation cost per patient, major reamputation rate, and complication rate.

METHODS

939 patients admitted to the Department of Orthopaedic Surgery, NUH, for DFP from 2002 (before team formation) to 2007 (after team formation). It consisted of six cohorts of patients - 61 for 2002, 70 for 2003, 148 for 2004, 180 for 2005, 262 for 2006, and 218 for 2007. All patients were managed by the NUH Multidisciplinary Diabetic Foot Team combined with a clinical pathway. Statistical analyses were carried out for five parameters (ALOS, hospitalisation cost per patient, major amputation rate, readmission rate, and complication rate).

RESULTS

From 2002 to 2007, the ALOS was significantly reduced from 20.36 days to 12.20 days (p=0.0005). Major amputation rate was significantly reduced from 31.15 to 11.01% (p<0.0005). There was also a significant reduction in complication rate from 19.67 to 7.34% (p=0.005). There were reductions in the hospitalisation cost per patient and readmission rate after formation of the multidisciplinary team but they were not statistically significant.

CONCLUSION

Our evaluation showed that a multidisciplinary team approach combined with the implementation of a clinical pathway in NUH was effective in reducing the ALOS, major amputation rate, and complication rate of DFP.

Safety and immunogenicity of influenza A H1N1 vaccines

Evaluation of: Liang XF, Wang HQ, Wang JZ et al. Safety and immunogenicity of 2009 pandemic influenza A H1N1 vaccines in China: a multicentre, double-blind, randomised, placebo-controlled trial. Lancet 375(9708), 56-66 (2009). The novel swine-origin influenza A H1N1 2009 virus was first identified in April 2009 in Mexico. Since then, it has caused a worldwide pandemic with more than 10,000 deaths documented by December 2009. While many countries adopted pandemic plans and border controls to try to control the spread of the virus, it was quickly realized that the virus was unstoppable. The virus was initially largely susceptible to oseltamivir and zanamivir, and various strategies that included treatment of severe cases, all cases or targeted chemoprophylaxis were used to try to limit the mortality and morbidity due to the virus. However, predictably, resistance to neuraminidase inhibitors has increasingly appeared in different settings and outbreaks of resistant virus have been reported. Mass vaccination is the most economic and effective measure to reduce infection and mortality from influenza. Before this pandemic, several studies were conducted using H5N1 prepandemic vaccines to try to determine the optimal composition and dose of vaccine for a novel strain of influenza. Most of these studies found significantly higher doses required for novel influenza strains and all previous studies showed the need for two doses of vaccine to achieve protective levels of antibody. Once it became apparent that the pandemic was due to H1N1 2009 instead, efforts were redirected to finding the optimal antigen dose and composition including the use of adjuvant combinations. This unique study conducted in ten centers across the People's Republic of China found that a single-dose, 7.5-microg, nonadjuvanted, split-virion vaccine was sufficiently immunogenic for adults and adolescents aged 12 years and above to meet regulatory requirements for registration. The vaccine was relatively well tolerated with serious adverse reactions--mainly high-grade fever in only 0.6% of vaccine recipients. This large, unique study conducted in a developing country using vaccine manufactured in that developing country shows a high degree of seroprotection and has had a major impact on pandemic vaccination strategies worldwide.

Diagnostic testing for pandemic influenza in Singapore: a novel dual-gene quantitative real-time RT-PCR for the detection of influenza A/H1N1/2009

With the relative global lack of immunity to the pandemic influenza A/H1N1/2009 virus that emerged in April 2009 as well as the sustained susceptibility to infection, rapid and accurate diagnostic assays are essential to detect this novel influenza A variant. Among the molecular diagnostic methods that have been developed to date, most are in tandem monoplex assays targeting either different regions of a single viral gene segment or different viral gene segments. We describe a dual-gene (duplex) quantitative real-time RT-PCR method selectively targeting pandemic influenza A/H1N1/2009. The assay design includes a primer-probe set specific to only the hemagglutinin (HA) gene of this novel influenza A variant and a second set capable of detecting the nucleoprotein (NP) gene of all swine-origin influenza A virus. In silico analysis of the specific HA oligonucleotide sequence used in the assay showed that it targeted only the swine-origin pandemic strain; there was also no cross-reactivity against a wide spectrum of noninfluenza respiratory viruses. The assay has a diagnostic sensitivity and specificity of 97.7% and 100%, respectively, a lower detection limit of 50 viral gene copies/PCR, and can be adapted to either a qualitative or quantitative mode. It was first applied to 3512 patients with influenza-like illnesses at a tertiary hospital in Singapore, during the containment phase of the pandemic (May to July 2009).

Oseltamivir ring prophylaxis for containment of 2009 H1N1 influenza outbreaks

BACKGROUND

From June 22 through June 25, 2009, four outbreaks of infection with the pandemic influenza A (H1N1) virus occurred in Singapore military camps. We report the efficacy of ring chemoprophylaxis (geographically targeted containment by means of prophylaxis) with oseltamivir to control outbreaks of 2009 H1N1 influenza in semiclosed environments.

METHODS

All personnel with suspected infection were tested and clinically isolated if infection was confirmed. In addition, we administered postexposure ring chemoprophylaxis with oseltamivir and segregated the affected military units to contain the spread of the virus. All personnel were screened three times weekly both for virologic infection, by means of nasopharyngeal swabs and reverse-transcriptase-polymerase-chain-reaction assay with sequencing, and for clinical symptoms, by means of questionnaires.

RESULTS

A total of 1175 personnel were at risk across the four sites, with 1100 receiving oseltamivir prophylaxis. A total of 75 personnel (6.4%) were infected before the intervention, and 7 (0.6%) after the intervention. There was a significant reduction in the overall reproductive number (the number of new cases attributable to the index case), from 1.91 (95% credible interval, 1.50 to 2.36) before the intervention to 0.11 (95% credible interval, 0.05 to 0.20) after the intervention. Three of the four outbreaks showed a significant reduction in the rate of infection after the intervention. Molecular analysis revealed that all four outbreaks were derived from the New York lineage of the 2009 H1N1 virus and that cases within each outbreak were due to transmission rather than unrelated episodes of infection. Of the 816 personnel treated with oseltamivir who were surveyed, 63 (7.7%) reported mild, nonrespiratory side effects of the drug, with no severe adverse events.

CONCLUSIONS

Oseltamivir ring chemoprophylaxis, together with prompt identification and isolation of infected personnel, was effective in reducing the impact of outbreaks of 2009 H1N1 influenza in semiclosed settings.

Seroconversion and asymptomatic infections during oseltamivir prophylaxis against Influenza A H1N1 2009

Background

Anti-viral prophylaxis is used to prevent the transmission of influenza. We studied serological confirmation of 2009 Influenza A (H1N1) infections during oseltamivir prophylaxis and after cessation of prophylaxis.

Methods

Between 22 Jun and 16 Jul 09, we performed a cohort study in 3 outbreaks in the Singapore military where post-exposure oseltamivir ring chemoprophylaxis (75 mg daily for 10 days) was administered. The entire cohort was screened by RT-PCR (with HA gene primers) using nasopharyngeal swabs three times a week. Three blood samples were taken for haemagglutination inhibition testing - at the start of outbreak, 2 weeks after completion of 10 day oseltamivir prophylaxis, and 3 weeks after the pandemic's peak in Singapore. Questionnaires were also administered to collect clinical symptoms.

Results

237 personnel were included for analysis. The overall infection rate of 2009 Influenza A (H1N1) during the three outbreaks was 11.4% (27/237). This included 11 index cases and 16 personnel (7.1%) who developed four-fold or higher rise in antibody titres during oseltamivir prophylaxis. Of these 16 personnel, 8 (3.5%) were symptomatic while the remaining 8 personnel (3.5%) were asymptomatic and tested negative on PCR. Post-cessation of prophylaxis, an additional 23 (12.1%) seroconverted. There was no significant difference in mean fold-rise in GMT between those who seroconverted during and post-prophylaxis (11.3 vs 11.7, p = 0.888). No allergic, neuropsychiatric or other severe side-effects were noted.

Conclusions

Post-exposure oseltamivir prophylaxis reduced the rate of infection during outbreaks, and did not substantially increase subsequent infection rates upon cessation. Asymptomatic infections occur during prophylaxis, which may confer protection against future infection. Post-exposure prophylaxis is effective as a measure in mitigating pandemic influenza outbreaks.