Performance of an automated chemiluminescence SARS-CoV-2 IG-G assay.

INTRODUCTION: We describe our evaluation of the Abbott SARS-CoV-2 IgG assay on the Architect immunoassay analyser. METHODS: We assessed assay precision, sensitivity, specificity, positive/negative predictive values (PPV/NPV), cross-reactivity (influenza/dengue/hepatitis B and C/rheumatoid factor/anti-nuclear/double-stranded DNA/syphilis) and sample throughput in samples from real-time polymerase chain reaction (RT-PCR) positive patients/healthcare workers (HCWs)/pre-pandemic samples. We compared the cut-off indexes (COIs) between all control samples (HCWs and pre-pandemic) to generate an optimised COI limit for reactivity. RESULTS: The assay specificity was 99.8% (n = 980) and sensitivity was 45.9-96.7% (n = 279). When tested ≥ 14 days post-positive RT-PCR (POS), the PPV/NPV was 96.4%/99.8%. The difference between the COIs of HCWs/pre-pandemic samples was small (0.01, p < 0.0001). There was minimal cross-reactivity with other antibodies. A lower COI limit for reactivity (≥0.55, using the 99th percentile COI of our controls and ROC analysis) improved diagnostic sensitivity, especially at 0-6 days POS (45.9-55.8%), with a small decrease in specificity (98.9%). The assay throughput was 100 samples in 70 min. CONCLUSION: The Abbott SARS-CoV-2 IgG assay shows excellent performance in patients ≥ 14 days POS. The difference between the COIs of HCWs and pre-pandemic samples was numerically small. A lower COI limit improves assay sensitivity with a slight decrease in specificity.

Purification and functional characterization of the first stilbene glucoside-specific ß-glucosidase isolated from Lactobacillus kimchi.

This study aimed to develop viable enzymes for bioconversion of resveratrol-glucoside into resveratrol. Out of 13 bacterial strains tested, Lactobacillus kimchi JB301 could completely convert polydatin into resveratrol. The purified enzyme had an optimum temperature of 30-40°C and optimum pH of pH 5.0 against polydatin. This enzyme showed high substrate specificities towards different substrates in the following order: isorhaponticin>>polydatin>>mulberroside A>oxyresveratrol-3-O-glucoside. Additionally, it rarely hydrolyzed astringin and desoxyrhaponticin. Based on these catalytic specificities, we suggest this enzyme be named stilbene glucoside-specific ß-glucosidase. Furthermore, polydatin extracts from Polygonum cuspidatum were successfully converted to resveratrol with a high yield (of over 99%). Stilbene glucoside-specific ß-glucosidase is the first enzyme isolated from lactic acid bacteria capable of bio-converting various stilbene glucosides into stilbene.

High anxiety, young age and long waits increase the need for preoperative sedatives in children.

OBJECTIVE: This prospective, observational study aimed to identify children likely to require sedation preoperatively by measuring anxiety levels using the modified Yale Preoperative Anxiety Scale (mYPAS). Other possible predictive factors for preoperative sedation were also investigated. METHODS: A total of 455 patients aged 2-12 years scheduled for surgery requiring general anaesthesia were enrolled in the study. Patients' anxiety levels were measured using the mYPAS in a preoperative holding area just before patients were separated from their parents or guardians and entered the operating theatre. Anaesthetists blindedto the mYPAS assessments judged whether the child could be separated and enter the operating theatre without a sedative. The ability of the mYPAS to predict the need for preoperative sedation was analysed by receiver operating characteristic (ROC) curve analysis. RESULTS: The optimum mYPAS cut-off for requiring sedatives was 41.7 according to ROC curve analysis. Multivariate logistic regression analysis showed that age, mYPAS>40 and waiting time were independent predictors of the requirement for sedative administration. CONCLUSIONS: High anxiety levels, young age and long waits contributed to the need for preoperative sedation in children.

Influenza A H1N1 (2009): clinical spectrum of disease among adult patients admitted to a regional hospital in Singapore.

INTRODUCTION: The worldwide spread of Influenza A H1N1 (2009) has proceeded at an unprecedented rate, with the World Health Organization rapidly raising its influenza pandemic alert to phase six. We describe the disease spectrum of H1N1 (2009) to aid the triaging and identification of patients at risk. METHODS: This is a retrospective chart review of all confirmed H1N1 (2009) cases admitted to our institution between June and September 2009. RESULTS: The disease severity of the 153 patients studied was classified as mild (n is 75), moderate (n is 55) and severe (n is 23). 81 patients were female. The median age was 26 years. While comorbidities were more prevalent among patients with moderate-severe illness, 47.4 percent reported no pre-existing illness. Presenting complaints of breathlessness, tachycardia, low-pulse oximetry, higher leukocyte counts and C-reactive protein with low albumin levels were more commonly noted in moderate-severe illness (p-value less than 0.001). All patients received oseltamivir at a median of four days from illness onset. 18 required intensive care unit admission, with the majority (94.4 percent) within the first 24 hours of hospitalisation. The overall mortality rate was 4.6 percent. Median lengths of hospitalisation were four and nine days for moderate and severe cases, respectively. CONCLUSION: While the majority of H1N1 (2009) patients have mild illness, a subgroup can become critically ill. Prior good health is not necessarily a good discriminator against severe illness. The presence of dyspnoea, tachycardia and desaturation at triage should heighten the index of suspicion for H1N1 (2009)-related complications.

Selective control of cyanobacteria in eutrophic pond by a combined device of ultrasonication and water pumps.

A combined device consisting of an ultrasonic apparatus and water pumps was operated in a eutrophic pond to study its effect on the control of cyanobacteria as compared with those of a non-treated, neighboring pond. The combined apparatus seemed to be enough to spread the sonicated water to the whole surface of a 9,000 m3 pond. Although the high rainfall in 2003 resulted in an overall dominance of diatoms, cyanobacterial growth was significantly inhibited by the apparatus in the treated pond. In addition, the chlorophyll-a concentration and total algae in the treated pond were 61 and 53%, respectively, of the levels in the control pond. The reduced algal growth (7% of the control) by the combined apparatus was mainly due to the inhibition on the growth of cyanobacteria. The cyanobacterial proportion in the treated pond, however, increased significantly for several days, when the apparatus was stopped. Meanwhile, the proportion of green algae increased in the treated pond. The successful selective control of cyanobacteria using the combined apparatus suggests that ultrasonication can be a practical method to control bloom and toxin production in eutrophic waters.

Growth inhibition of bloom-forming cyanobacterium Microcystis aeruginosa by rice straw extract.

AIMS: To inhibit the growth of the bloom-forming cyanobacterium Microcystis aeruginosa using a rice straw extract. METHODS AND RESULTS: The cell numbers of the algal strain M. aeruginosa UTEX 2388 significantly decreased after treatment with different concentrations (0.01, 0.1, 1 and 10 mg l(-1)) of a rice straw extract for an 8-day cultivation period. Among seven tested allelochemicals from rice straw, salicylic acid at 0.1 mg l(1) exhibited the highest allelopathic activity (26%) on day 8. A synergistic effect on algal growth inhibition was found when adding two or three phenolic compounds from the rice straw. CONCLUSIONS: The growth of M. aeruginosa was inhibited by rice straw extract concentrations ranging from 0.01 to 10 mg l(1). This activity was due to the synergistic effects of various phenolic compounds in the rice straw. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of rice straw as an effective material for the growth inhibition of M. aeruginosa implies it may have the potential to be used as an environment-friendly biomaterial for controlling the algal bloom of M. aeruginosa in eutrophic water.

Epidemiology and clinical outcome of enterococcal bacteraemia in an acute care hospital.

OBJECTIVE: To determine the epidemiology and clinical outcome of enterococcal bacteraemia in an acute care hospital. MATERIALS AND METHODS: This is a retrospective study on enterococcal bacteraemia in an acute hospital from January 1999 to June 2001. Patients' clinical case notes were reviewed and their demographic, clinical and microbiological data were recorded. RESULTS: A total of 42 patients (25 males and 17 females) were included in the study, their mean age was 74.8+/-10.9 years. The majority of them had underlying diabetes mellitus and neurological disease. Seventeen patients required intensive care. Sources of enterococcal bacteraemia were identified in 21 cases (urinary tract, 13 patients; hepatobiliary, five; cardiovascular, two and soft tissues, one patient). Eighteen patients had prior invasive procedures. All the Enterococcus species isolated were vancomycin-susceptible; however, eight were ampicillin-resistant and 13 had high-level gentamicin resistance. Shock, disseminated intravascular coagulopathy, acute renal failure and cardiorespiratory arrest occurred in 42% of the cases. Antibiotics were prescribed appropriately in 31 patients and seven deaths were recorded. Of the 11 patients who received inappropriate therapy, six deaths were recorded. Inappropriate antibiotic therapy was associated with mortality. The mortality rate was 31%. Only one patient had a relapse of enterococcal bacteraemia from urinary tract infection secondary to underlying ureteric stricture. There were no vancomycin resistant cases. CONCLUSION: Urinary tract infection was the most common source of enterococcal bacteraemia. Appropriate antibiotics were essential in treating bacteraemia to reduce mortality. Vancomycin-resistant Enterococcus was not detected. The presence of comorbid conditions and invasive procedures in patients with enterococcal bacteraemia were found in 86 and 71% of patients, respectively.

Harvesting of Spirulina platensis by cellular flotation and growth stage determination.

AIM: To investigate an effective harvesting method for Spirulina platensis. METHODS AND RESULTS: Eighty per cent of S. platensis cells in the logarithmic growth phase were harvested by flotation when the cells were set in a static condition for 2 h. The optimum harvesting time was about day 6 of cultivation. The flotation activity of S. platensis cells was enhanced by the addition of NaCl. CONCLUSIONS: The harvesting of S. platensis by flotation is a cost-effective and straightforward method that can retain the algal quality. The optimum harvesting time of S. platensis can be predicted by the cellular protein to carbon ratio. SIGNIFICANCE AND IMPACT OF THE STUDY: Flotation harvesting is also applicable to other cyanobacteria with gas vesicles.

Extended-spectrum beta-lactamases in clinical isolates of Escherichia coli and Klebsiella spp. in a Singapore hospital: clinical spectrum.

INTRODUCTION: The rising prevalence of extended-spectrum beta-lactamases in gram-negative bacillary pathogens is an important clinical problem resulting from the extensive use of broad-spectrum antibiotics. The emergence of the extended-spectrum beta-lactamases increases the possibility that traditional, empiric antimicrobial regimens may be ineffective. The aims of this study are: to determine the epidemiologic characteristics and clinical outcome of patients diagnosed with infection caused by Klebsiella spp. and Escherichia coli producing extended-spectrum beta-lactamases; to define a subgroup of patients who may benefit from early, empiric therapy; and to determine the local antibiotic sensitivity pattern in order to improve antibiotic utilisation in our hospital. MATERIALS AND METHODS: A 4-month retrospective review of patients hospitalised in Changi General Hospital between November 2000 and February 2001 who were diagnosed with infection caused by isolates of Klebsiella spp. or Escherichia coli producing extended-spectrum beta-lactamases. RESULTS: During the study period, 44 % of Klebsiella spp. and 16.1 % of Escherichia coli isolates were reported as producers of the extended-spectrum beta-lactamases. Sixty-eight patients were assessed to have clinically significant infection caused by 75 isolates. Most of them were elderly, had multiple medical problems and were recently treated with beta-lactam antibiotics. There was a trend toward better outcome in patients who received adequate initial, empiric therapy. CONCLUSION: Patients with infections caused by extended-spectrum beta-lactamase producing Enterobacteriaceae have certain identifiable, common clinical characteristics. In our institution, only carbapenems remain effective against all isolates of Klebsiella spp. or Escherichia coli producing extended-spectrum beta-lactamases. Further research is necessary to define a group of patients who can benefit from an early, broad-spectrum, empiric therapy.

Dapsone hypersensitivity syndrome masquerading as a viral exanthem: three cases and a mini-review.

INTRODUCTION: We report 3 cases of dapsone hypersensitivity syndrome due to anti-malarial chemoprophylactic treatment with maloprim, in military servicemen, presenting like a viral exanthem. CLINICAL PICTURE: Three male military recruits presented with fever and rash, 6 to 8 weeks after commencing on weekly doses of maloprim. TREATMENT: A course of topical and systemic corticosteroids and oral antihistamines were started. OUTCOME: All cases showed gradual resolution of fever, rash and eventual normalisation of liver function test. CONCLUSION: A high index of suspicion was required before this uncommon syndrome can be recognised. Early institution of corticosteroid therapy and discontinuation of maloprim are the mainstays of treatment.

A case of right loin pain: septic ovarian vein thrombosis due to Campylobacter fetus bacteraemia.

INTRODUCTION: Septic ovarian venous thrombosis is an uncommon condition. Diagnosis is often not immediately apparent clinically and there are many that mimic this condition. We described an unusual case of septic ovarian vein thrombosis associated with Campylobacter fetus (C. fetus) bacteraemia. CLINICAL PICTURE: A 46-year-old female presented with fever and acute right loin pain. Right ovarian venous thrombosis was demonstrated on sonography and confirmed with computed tomography and magnetic resonance imaging. C. fetus was isolated from the blood. TREATMENT AND OUTCOME: The patient was given antibiotics and anticoagulation therapy with good response. CONCLUSION: Septic ovarian vein thrombosis should be considered as a differential diagnosis in female patients presenting with fever associated with lower abdominal pain. C. fetus bacteraemia also predisposes to thrombophlebitis, including septic ovarian vein thrombosis. When they are diagnosed in a timely manner and treated appropriately, the response is good and potential serious complications, including thromboembolism, and death could be averted. Radiological imaging is useful in the diagnostic work-up of this condition.

Localised outbreak of Falciparum malaria in Singapore.

Malaria is primarily an imported disease in Singapore. Local outbreaks are uncommon. We describe a localised outbreak of three patients with Falciparum malaria, which we believe to be locally acquired. There was one fatality due to severe disease and late presentation. Malaria should be considered as a cause of febrile illness as the likelihood of cure depends on early detection and treatment.

An efficient method for the rapid establishment of Epstein-Barr virus immortalization of human B lymphocytes.

Several methods have been developed for the immortalization of B lymphocytes by Epstein-Barr virus (EBV). We developed an efficient method which reduces the time from culture initiation to immortalization and cryopreservation. Two infections of EBV to lymphocytes, and the use of phorbol ester-induced EBV stock significantly improved immortalization efficiency and reduced the time between initiation and immortalization and cryopreservation. The resulting cell bank was used to produce DNA for genetic studies focusing on the genes involved in immune and autistic disorders.

Microcystin-induced down-regulation of lymphocyte functions through reduced IL-2 mRNA stability.

Here we report that lymphocyte functions were down-regulated by cyanobacterial hepatotoxin microcystin. Treatment of three microcystin (MC) isotypes, MC-LR, MC-YR and nodularin, on B6C3F1 mouse splenocytes produced dose-dependent inhibition of in vitro polyclonal antibody response and lymphoproliferation to LPS. ConA-induced lymphoproliferative response was decreased by MC-YR and nodularin, but no significant effect was observed in the MC-LR treatment. Intraperitoneal administration of nodularin into B6C3F1 mice decreased humoral immune responses to sheep red blood cell (sRBC), and the inhibitory effect became severe when hepatic uptake of nodularin was blocked by rifampicin. Each MC 1 microM suppressed phorbol 12-myristate 13-acetate (PMA) plus ionomycin-induced IL-2 mRNA expression in splenocytes and thymocytes, but not in EL-4 mouse thymoma cells. To further characterize the mechanism for the reduced IL-2 mRNA level, IL-2 mRNA stability was measured using RT-PCR. Deprivation of PMA/ionomycin stimuli from activated splenocytes and blockade of new transcription resulted in destabilization of IL-2 mRNA, which was accelerated by MC treatment. These results demonstrated that MC down-regulated lymphocyte functions and the immunosuppression was mediated, at least in part, through decreased IL-2 mRNA stability.

Seasonal variation and indirect monitoring of microcystin concentrations in Daechung reservoir, Korea.

Physicochemical and biological water quality, including the microcystin concentration, was investigated from spring to autumn 1999 in the Daechung Reservoir, Korea. The dominant genus in the cyanobacterial blooming season was Microcystis. The microcystin concentration in particulate form increased dramatically from August up to a level of 200 ng liter(-1) in early October and thereafter tended to decrease. The microcystin concentration in dissolved form was about 28% of that of the particulate form. The microcystins detected using a protein phosphatase (PP) inhibition assay were highly correlated with those microcystins detected by a high-performance liquid chromatograph (r = 0.973; P < 0.01). Therefore, the effectiveness of a PP inhibition assay for microcystin detection in a high number of water samples was confirmed as easy, quick, and convenient. The microcystin concentration was highly correlated with the phytoplankton number (r = 0.650; P < 0.01) and chlorophyll-a concentration (r = 0.591; P < 0.01). When the microcystin concentration exceeded about 100 ng liter(-1), the ratio of particulate to dissolved total nitrogen (TN) or total phosphorus (TP) converged at a value of 0.6. Furthermore, the microcystin concentration was lower than 50 ng liter(-1) at a particulate N/P ratio below 8, whereas the microcystin concentration varied quite substantially from 50 to 240 ng liter(-1) at a particulate N/P ratio of >8. Therefore, it seems that the microcystin concentration in water can be estimated and indirectly monitored by analyzing the following: the phytoplankton number and chlorophyll-a concentration, the ratio of the particulate and the dissolved forms of N and P, and the particulate N/P ratio when the dominant genus is toxigenic Microcystis.

Teicoplanin-induced neutropenia in a paediatric patient with vertebral osteomyelitis.

Teicoplanin is a glycopeptide antibiotic that has been used extensively in adults but less so in children for the treatment of bone and joint infections. It has a good safety profile with low incidences of blood dyscrasias. We report a case of teicoplanin-induced neutropenia in a child.

Shigella septicaemia in adults: report of two cases and mini-review.

INTRODUCTION: We report 2 cases of Shigella septicaemia in adult patients. CLINICAL PICTURE: Two 57-year-old women presented with non-bloody diarrhoea and fever. The first patient was an inmate of a long-term care facility who was schizophrenic and the second patient was a diabetic who recently travelled to Medan, Indonesia. Both patients were febrile, hypotensive and dehydrated. The first patient was neutropenic, thrombocytopenic and had acute renal failure. Blood cultures yielded Shigella flexneri and stool cultures gave negative results for both patients. TREATMENT: Rehydration and intravenous ceftriaxone were instituted. OUTCOME: The patients' symptoms and hypotension resolved. CONCLUSION: Appropriate antibiotics can decrease the severity and duration of Shigella septicaemia.

Attitudes and beliefs of Singapore health care professionals concerning HIV/AIDS.

AIM OF STUDY: This study examines the beliefs and attitudes of Singapore doctors, dentists, and nurses concerning HIV/AIDS and persons living with HIV/AIDS (PWAs). METHOD: A mail survey was done of all doctors and dentists in Singapore as well as a random sample of 1,500 nurses from the Singapore Nursing Board Register. RESULTS: The results showed that respondents held accurate beliefs concerning transmission of HIV via sex and needle sharing but a significant proportion also expressed belief in transmission via everyday social contact. Respondents were aware of universal precautions when treating persons with HIV/AIDS but tended to be overly cautious in low/no risk situations. A substantial proportion of respondents indicated little or no knowledge or experience with AIDS-related conditions and the majority believed that most health care professionals are unprepared to care for PWAs. Further, there was evidence of substantial stigmatisation and fear of treating PWAs, both of which were significantly and negatively correlated with accuracy of beliefs about HIV transmission and universal precautions. CONCLUSION: These results point to important misconceptions about HIV/AIDS held by Singapore health care professionals as well as stigma towards and fear of treating PWAs. These are areas that need to be addressed through better professional education concerning HIV/ AIDS. This education needs to address both the factual misconceptions about HIV/AIDS as well as the stigma associated with this disease and the fears that health care professionals have of treating PWAs.

Variation of microcystin content of microcystis aeruginosa relative to medium N:P ratio and growth stage.

Changes in the microcystin content of Microcystis aeruginosa UTEX 2388 were investigated at several N:P ratios of the medium and various growth stages. Under the P-fixed condition, the microcystin content of the cells changed with different medium N:P ratios, with the highest at 2748 microg g-1 at a N:P ratio of 16 after incubation for 7 d. The microcystin content of M. aeruginosa exhibited a high correlation with the total N content regardless of an N-fixed or P-fixed culture. When the N:P ratio of the medium was fixed to 16 : 1, the microcystin content of M. aeruginosa at various growth stages was highest at 2191 microg g-1 after an incubation of 4 d and the chlorophyll-a content showed a similar tendency. There was a highly significant relationship between the microcystin content of M. aeruginosa and the chlorophyll-a concentration in the culture during the incubation. Accordingly, the microcystin content of M. aeruginosa during incubation can be easily estimated and monitored by measuring the in vivo fluorescence changes in the culture.