Association between minimum inhibitory concentration, beta-lactamase genes and mortality for patients treated with piperacillin/tazobactam or meropenem from the MERINO study

INTRODUCTION

This study aims to assess the association of piperacillin/tazobactam and meropenem minimum inhibitory concentration (MIC) and beta-lactam resistance genes with mortality in the MERINO trial.

METHODS

Blood culture isolates from enrolled patients were tested by broth microdilution and whole genome sequencing at a central laboratory. Multivariate logistic regression was performed to account for confounders. Absolute risk increase for 30-day mortality between treatment groups was calculated for the primary analysis (PA) and the microbiologic assessable (MA) populations.

RESULTS

320 isolates from 379 enrolled patients were available with susceptibility to piperacillin/tazobactam 94% and meropenem 100%. The piperacillin/tazobactam non-susceptible breakpoint (MIC > 16 mg/L) best predicted 30-day mortality after accounting for confounders (odds ratio 14.9, 95% CI 2.8 - 87.2). The absolute risk increase for 30-day mortality for patients treated with piperacillin/tazobactam compared with meropenem was 9% (95% CI 3% - 15%) and 8% (95% CI 2% - 15%) for the original PA population and the post-hoc MA populations, which reduced to 5% (95% CI -1% - 10%) after excluding strains with piperacillin/tazobactam MIC values > 16 mg/L. Isolates co-harboring ESBL and OXA-1 genes were associated with elevated piperacillin/tazobactam MICs and the highest risk increase in 30-mortality of 14% (95% CI 2% - 28%).

CONCLUSION

After excluding non-susceptible strains, the 30-day mortality difference was from the MERINO trial was less pronounced for piperacillin/tazobactam. Poor reliability in susceptibility testing performance for piperacillin/tazobactam and the high prevalence of OXA co-harboring ESBLs suggests meropenem remains the preferred choice for definitive treatment of ceftriaxone non-susceptible E. coli and Klebsiella.

Implementation hurdles of an interactive, integrated, point-of-care computerised decision support system for hospital antibiotic prescription

Antimicrobial stewardship is used to combat antimicrobial resistance. In Singapore, a tertiary hospital has integrated a computerised decision support system, called Antibiotic Resistance Utilisation and Surveillance-Control (ARUSC), into the electronic inpatient prescribing system. ARUSC is launched either by the physician to seek guidance for an infectious disease condition or via auto-trigger when restricted antibiotics are prescribed. This paper describes the implementation of ARUSC over three phases from 1 May 2011 to 30 April 2013, compared factors between ARUSC launches via auto-trigger and for guidance, examined factors associated with acceptance of ARUSC recommendations, and assessed user acceptability. During the study period, a monthly average of 9072 antibiotic prescriptions was made, of which 2370 (26.1%) involved ARUSC launches. Launches via auto-trigger comprised 48.1% of ARUSC launches. In phase 1, 23% of ARUSC launches were completed. This rose to 38% in phase 2, then 87% in phase 3, as escapes from the ARUSC programme were sequentially disabled. Amongst completed launches for guidance, 89% of ARUSC recommendations were accepted versus 40% amongst completed launches via auto-trigger. Amongst ARUSC launches for guidance, being from a medical department [adjusted odds ratio (aOR)=1.20, 95% confidence interval (CI) 1.04-1.37] and ARUSC launch during on-call (aOR=1.81, 95% CI 1.61-2.05) were independently associated with acceptance of ARUSC recommendations. Junior physicians found ARUSC useful. Senior physicians found ARUSC reliable but admitted to having preferences for antibiotics that may conflict with ARUSC. Hospital-wide implementation of ARUSC encountered hurdles from physicians. With modifications, the completion rate improved.

Can intra-articular therapies prior to total knee arthroplasty increase the risk of periprosthetic infection?

Intra-articular therapies, such as steroid injection, viscosupplement injection and acupuncture, are common non-surgical options for patients with osteoarthritis of the knee. With any intra-articular injection or acupuncture procedure, there is a potential for inoculation with bacteria leading to possible knee infection. The authors report a patient who incurred an acute infection found after a total knee arthroplasty attributed to prior acupuncture procedure done as part of conservative treatment.

Rapidly growing mycobacteria in Singapore, 2006-2011

Nontuberculous mycobacteria infection is a growing global concern, but data from Asia are limited. This study aimed to describe the distribution and antibiotic susceptibility profiles of rapidly growing mycobacterium (RGM) isolates in Singapore. Clinical RGM isolates with antibiotic susceptibility tests performed between 2006 and 2011 were identified using microbiology laboratory databases and minimum inhibitory concentrations of amikacin, cefoxitin, clarithromycin, ciprofloxacin, doxycycline, imipenem, linezolid, moxifloxacin, sulfamethoxazole or trimethoprim-sulfamethoxazole, tigecycline and tobramycin were recorded. Regression analysis was performed to detect changes in antibiotic susceptibility patterns over time. A total of 427 isolates were included. Of these, 277 (65%) were from respiratory specimens, 42 (10%) were related to skin and soft tissue infections and 36 (8%) were recovered from blood specimens. The two most common species identified were Mycobacterium abscessus (73%) and Mycobacterium fortuitum group (22%), with amikacin and clarithromycin being most active against the former, and quinolones and trimethoprim-sulfamethoxazole against the latter. Decreases in susceptibility of M. abscessus to linezolid by 8.8% per year (p 0.001), M. fortuitum group to imipenem by 9.5% per year (p 0.023) and clarithromycin by 4.7% per year (p 0.033) were observed. M. abscessus in respiratory specimens is the most common RGM identified in Singapore. Antibiotic options for treatment of RGM infections are increasingly limited.

Acute HIV infection in Singapore: predominance of men who have sex with men

INTRODUCTION

The incidence of human immunodeficiency virus (HIV) infection in Singapore is on the rise. We aimed to study the clinical epidemiology of acute HIV infection in Singapore.

METHODS

All patients that fulfilled the criteria for definite and probable acute HIV infection were prospectively identified from January 1, 2003 to June 30, 2006. Demographic, clinical and laboratory data were recorded.

RESULTS

A total of 16 out of 34 patients had definite acute HIV infection, and 68 percent of the entire cohort comprised men who have sex with men (MSM). Ten percent of the patients were co-infected with hepatitis B and C viruses, while 27 percent were infected with syphilis. Signs and symptoms were nonspecific, with fever, rash and diarrhoea being the three most common symptoms. Only 35 percent of the patients required hospitalisation.

CONCLUSION

Men who have sex with men account for the majority of patients with acute HIV infections in Singapore, many of them also being co-infected with syphilis. Safer sex campaign among MSM should be implemented or intensified.

The benign nature of acute dengue infection in hospitalized older adults in Singapore

OBJECTIVES

In Singapore, dengue primarily affects adults. This study aimed to determine if older dengue patients in Singapore have greater morbidity and mortality.

METHODS

All laboratory diagnosed dengue patients admitted to Tan Tock Seng Hospital in 2004 were retrospectively reviewed. Cases were re-classified into dengue fever and dengue hemorrhagic fever based on World Health Organization criteria. Demographic, clinical, laboratory, and outcome data of patients aged > or = 60 years and <60 years were collected.

RESULTS

Of 1971 laboratory confirmed dengue cases, 66 were aged > or = 60 years. Older patients were significantly less likely to be male (44% vs. 64%), and more likely to have diabetes (17% vs. 2%), hypertension (48% vs. 4%), ischemic heart disease (6% vs. 0.1%), hyperlipidemia (18% vs. 1%), and secondary dengue infections (64% vs. 34%). Clinical features were similar except older patients were significantly less likely to report fever (92% vs. 99%), or have leukopenia (32% vs. 51%) or hemoconcentration (0 vs. 5%) on admission. Older patients had similar dengue hemorrhagic fever, bleeding, hypotension, severe thrombocytopenia, and elevated transaminase rates. Length of hospital stay, risk of intensive care unit admission, and outcome of death were not statistically different.

CONCLUSIONS

Despite greater co-morbidity and secondary dengue infection, older dengue patients in Singapore did not have greater morbidity or mortality.

Clinical features and epidemiology of chikungunya infection in Singapore

Chikungunya is a re-emerging mosquito-borne viral infection that has spread from East Africa to Indian Ocean islands and re-emerged in India since 2004. In Malaysia, chikungunya re-emerged after a hiatus of seven years, causing a localised outbreak in a north-western coastal town in 2006 and subsequently widespread outbreaks in 2008. Since the first local outbreak of chikungunya in Singapore in January 2008, chikungunya infections have been increasingly reported in Singapore. In this case series, five patients aged 37-62 years, with chikungunya infection confirmed in August 2008, were reported. Three of the five were male, and only one had medical comorbidities. Two had a travel history to Johor, Malaysia, where local outbreaks of chikungunya had been reported. Fever, arthralgia and rash were the most common symptoms. Fever lasted four to five days while viraemia lasted four to 11 days, persisting two to three days after defervescence in three patients. A biphasic pattern of fever was observed in two patients. Leucopenia was noted in all patients, while mild thrombocytopenia and transaminitis occurred in three of five patients. Two patients had persistent polyarthralgia at two to three weeks after the onset of symptoms. Fever, arthralgia and rash should prompt consideration of acute chikungunya in Singapore. While taking the travel history, doctors should be mindful that indigenous chikungunya cases can occur.

Decision tree algorithm in deciding hospitalization for adult patients with dengue haemorrhagic fever in Singapore

OBJECTIVES

To develop a simple decision tree for clinicians to decide between hospitalization and outpatient monitoring of adult dengue patients.

METHOD

Retrospective cohort study on all laboratory-diagnosed dengue patients admitted in 2004 to Tan Tock Seng Hospital, Singapore. Demographic, clinical, laboratory and radiological data were collected, and cases classified as dengue fever (DF) or dengue haemorrhagic fever (DHF) using World Health Organization criteria. To develop the decision tree, we used chi-squared automatic interaction detector (CHAID) with bi-way and multi-way splitting. The resulting trees were pruned to achieve the highest sensitivity with the shortest tree.

RESULTS

In 2004, 1973 probable and confirmed adult dengue patients were admitted; DF comprised 1855 (94.0%) and DHF 118 (6.0%) of the cases. The best decision tree prediction had three branches, consisting of a history of clinical bleeding, serum urea, and serum total protein. This decision tree had a sensitivity of 1.00, specificity of 0.46, positive predictive value of 7.5%, and negative predictive value of 100%. The overall accuracy of the decision tree was 48.1%. The test sensitivity and specificity compared favourably with other predictive probability equations and sophisticated laboratory tests, and would prevent 43.9% of mild DF cases from hospitalization.

CONCLUSIONS

A simple decision tree is effective in predicting DHF in the clinical setting for adult dengue infection.

New influenza A (H1N1) 2009 in Singapore: the first ten adult imported cases

INTRODUCTION

Since late March 2009, a novel influenza H1N1 strain emerged in humans in Mexico and the United States. It has rapidly spread to many countries on different continents, prompting unprecedented activation of pandemic preparedness plans. Singapore has adopted a containment strategy with active screening of febrile travellers with respiratory symptoms from affected countries since April 27, 2009.

METHODS

All cases with new influenza A (H1N1) confirmed on polymerase chain reaction assay on combined nasal and throat swabs and who were admitted to the Communicable Disease Centre, were included in a prospective evaluation of clinical characteristics of new influenza A (H1N1).

RESULTS

From May 26 to June 3, 2009, there were ten patients with a mean age of 27.6 years, seven of whom were female. All but one travelled from the United States, six of whom travelled from New York; the last one travelled from the Philippines. Clinical illness developed within a mean of 1.4 days after arrival in Singapore, and presentation to the emergency department at a mean of 2.7 days from illness onset. Fever occurred in 90 percent, cough 70 percent, coryza 40 percent, sore throat and myalgia/arthralgia 30 percent; none had diarrhoea. The fever lasted a mean of 2.1 days. All were treated with oseltamivir. The clinical course was uncomplicated in all cases.

CONCLUSION

Clinical features of new influenza A (H1N1) appeared mild, and ran an uncomplicated course in immunocompetent patients.

Reducing antimicrobial resistance through appropriate antibiotic usage in Singapore

Two alarming trends threaten the future utility of antimicrobial agents: rise of antimicrobial resistance and decline in development of new antibiotics. The continuing emergence and spread of antimicrobial-resistant microbes--a global public health issue--exacerbates the problem of paucity of new antimicrobial agents. Singapore's public sector hospitals currently have some of the highest rates of antimicrobial resistance worldwide, evolving with surprising speed over the past two decades. Because there was no systematic surveillance until fairly recently, this healthcare problem has not been emphasised. In contrast, it is difficult to assess the scale of antimicrobial resistance in the community in view of the lack of recent research, although indirect evidence suggests that this is also a source of concern. A panel comprising representatives from multiple professional healthcare societies was convened to address the issue of antimicrobial resistance in Singapore, focusing on the conservation of antibiotics against resistance. From a review of the medical literature, potentially successful strategies involve facilitating prudent and appropriate use of antimicrobial agents in tandem with other interventions in infection control. Presently, there is a lack of data on the appropriate use of antibiotics in Singapore. The recommendations of the panel are: The professions should look into ways and means to support systematic data collection on antibiotic use and appropriateness of use; The Ministry of Health should take a more active and positive role in regulating antibiotic usage; Hospitals should actively support effective antimicrobial stewardship programmes; Educators should coordinate programmes to give greater emphasis on appropriate antimicrobial prescription, and support good clinical practice; and, Local and regional branches of pharmaceutical companies should adopt the Pharmaceutical Research and Manufacturers of America's updated code of conduct on interactions with physicians as a step towards re-aligning the industry-physician relationship in the direction of educational and informational support.

Do young adults with uncomplicated dengue fever need hospitalisation? A retrospective analysis of clinical and laboratory features

INTRODUCTION

Approximately 80 percent of all notified cases of dengue infections in Singapore were hospitalised from 2000 to 2005. We aimed to determine if hospitalised dengue patients had significant morbidity and mortality, and if admissions were in accordance with previously-published admission criteria.

METHODS

The medical records of the first 20 patients with laboratory-confirmed dengue from two consecutive months in three time periods were retrospectively reviewed. Demographical, clinical and laboratory data on admission, during hospitalisation and on discharge, were compared.

RESULTS

There were 120 patients with a mean age of 35 years. Males comprised 77 percent and foreign workers 51 percent. Of the published admission criteria, 33 percent had vomiting, 22 percent diarrhoea, 13 percent abdominal pain, 18 percent bleeding and one patient had hypotension. 30 percent were above the minimum platelet threshold of 80,000/microL, but 50 percent had safe levels of platelets between 50,000 and 80,000/microL. Dengue haemorrhagic fever occurred in 4 percent with no death. After admission, platelet nadir was below 20,000/microL in only 9 percent and below 10,000/microL in only 2 percent of cases. Bleeding did not correlate with platelet count. Medical referral to the hospital was significantly associated with thrombocytopenia, while self-referral was significantly associated with vomiting.

CONCLUSION

Severe adverse outcome among young adults with uncomplicated dengue fever is rare. Instead of hospitalisation, daily outpatient monitoring with symptomatic treatment and medical leave may be a safe and feasible alternative.