Normothermic ex vivo perfusion provides superior organ preservation and enables viability assessment of hearts from DCD donors.

The shortage of donors in cardiac transplantation may be alleviated by the use of allografts from donation after circulatory death (DCD) donors. We have previously shown that hearts exposed to 30 min warm ischemic time and then flushed with Celsior supplemented with agents that activate ischemic postconditioning pathways, show complete recovery on a blood-perfused ex vivo working heart apparatus. In this study, these findings were assessed in a porcine orthotopic heart transplant model. DCD hearts were preserved with either normothermic ex vivo perfusion (NEVP) using a clinically approved device, or with standard cold storage (CS) for 4 h. Orthotopic transplantation into recipient animals was subsequently undertaken. Five of six hearts preserved with NEVP demonstrated favorable lactate profiles during NEVP and all five could be weaned off cardiopulmonary bypass posttransplant, compared with 0 of 3 hearts preserved with CS (p < 0.05, Fisher's exact test). In conclusion, DCD hearts flushed with supplemented Celsior solution and preserved with NEVP display viability before and after transplantation. Viability studies of human DCD hearts using NEVP are warranted.

Increasing the tolerance of DCD hearts to warm ischemia by pharmacological postconditioning.

Donation after circulatory death (DCD) offers a potential additional source of cardiac allografts. We used a porcine asphyxia model to evaluate viability of DCD hearts subjected to warm ischemic times (WIT) of 20­40 min prior to flushing with Celsior (C) solution. We then assessed potential benefits of supplementing C with erythropoietin, glyceryl trinitrate and zoniporide (Cs), a combination that we have shown previously to activate ischemic postconditioning pathways. Hearts flushed with C/Cs were assessed for functional, biochemical and metabolic recovery on an ex vivo working heart apparatus. Hearts exposed to 20-min WIT showed full recovery of functional and metabolic profiles compared with control hearts (no WIT). Hearts subjected to 30- or 40-min WIT prior to C solution showed partial and no recovery, respectively. Hearts exposed to 30-min WIT and Cs solution displayed complete recovery, while hearts exposed to 40-min WIT and Cs solution demonstrated partial recovery. We conclude that DCD hearts flushed with C solution demonstrate complete recovery up to 20-min WIT after which there is rapid loss of viability. Cs extends the limit of WIT tolerability to 30 min. DCD hearts with ≤30-min WIT may be suitable for transplantation and warrant assessment in a transplant model.

Surveillance of antimicrobial resistance of Salmonella enterica serotype Typhi in seven Asian countries.

Two hundred and four Salmonella enterica serotype Typhi (S. Typhi) isolates were collected from seven Asian countries during 2002-2004. Multidrug-resistant S. Typhi (resistant to > or = 3 antibiotics) was detected in 84 (41.2%) isolates and 142 (69.6%) showed reduced susceptibility to ciprofloxacin (minimum inhibitory concentration=0.125-1.0 mg/l). This study highlights the worsening situation of antimicrobial resistance of S. Typhi in Asia.

Sequence and phylogenetic analysis of SH, G, and F genes and proteins of Human respiratory syncytial virus isolates from Singapore.

To study the genetic variability and molecular epidemiology of Human respiratory syncytial virus (HRSV) occurring in Singapore, nucleotide sequencing of three membrane-associated genes (SH, G and F) of four local isolates was performed. Comparison of their nucleotide and amino acid sequences with those of the prototype strains A2 (subgroup A) and CH-18537 (subgroup B) indicated that the Singapore isolates belong to the subgroup A. Comparison of the Singapore isolates with the reference strain A2 showed that whereas the G protein was the most divergent with up to 15% difference, the F and SH proteins showed less diversity of only up to 4%. Each gene exhibited its distinct variable and conserved regions. The N- and O-glycosylation sites within the G protein of the isolates were analyzed to ascertain their potential implications on the antigenicity of the viral glycoprotein. Based on the second variable region of the G protein, phylogenetic analysis of the Singapore isolates with 91 previously identified genotypes of subgroup A revealed that more than one genotype (GA2 and GA5) may circulate in the local population at a given time. This epidemiological study reflects the pattern of genetic relationships between the HRSV isolates from Singapore to those from other parts of the world.

What is true community-acquired urinary tract infection? Comparison of pathogens identified in urine from routine outpatient specimens and from community clinics in a prospective study.

In order to identify the true nature of community-acquired urinary tract infections, the uropathogens isolated from 100 patients with urinary tract infection included in a prospective study conducted in community clinics were compared to 244 isolates from outpatient urine specimens routinely submitted to the laboratory. Significant differences in both the spectrum of bacteria and their antibiograms were found between the two groups. Laboratory data analysis of uropathogens from outpatient urine specimens may not reflect the true bacteriology of urinary tract infections acquired in the community. Hence, surveys based on laboratory data alone may overestimate resistance rates, leading to misinformed choices being made when treatment is empirical.

Adult community acquired bacterial meningitis in a Singaporean teaching hospital. A seven-year overview (1993-2000).

BACKGROUND: The objective of this study is to describe the bacteriological, clinical and laboratory features of community acquired bacterial meningitis in adults admitted to a Singapore tertiary-care hospital. METHODS: Two hundred sixty-nine cases of meningitis or meningoencephalitis admitted between 1993 and 2000 were identified by their discharge diagnosis codes. All case records except for 57 which could not be retrieved were retrospectively reviewed. Patients less than 14 years or with skull fractures, post-neurosurgery or with indwelling intracranial devices were excluded. Inclusion criteria was a clinical picture compatible with a diagnosis of bacterial meningitis with either (1) positive cerebral-spinal fluid (CSF) cultures or latex coagglutination or CSF neutrophilic pleocytosis accompanied by positive blood cultures or (2) in the absence of positive blood cultures, CSF cultures and latex agglutination, presence of CSF pleocytosis of at least 100 neutrophils per microL. RESULTS: Fifteen "culture-positive" and 11 "culture negative" cases were identified. Six (55%) of the "culture-negative" cases received antibiotics prior to admission. Cultures grew Streptococcus pneumoniae in four cases, three cases each of Group B streptococci and Neisseria meningitides. Listeria monocytogenes and Klebsiella pneumoniae were each seen twice and Streptococcus suis once. All cases of Group B streptococci occurred in the year 1998. Mortality was 19% (n = 5), six developed infections in other sites, three epileptic seizures, three developed hydrocephalus, and two hearing loss. CONCLUSIONS: Pathogens are similar to those reported in other studies but for an outbreak of Group B Streptococcus in 1998. There were a high number of "culture-negative" cases which may be due to preceding antibiotic intervention.

The pattern of utilisation and accuracy of a commercial nucleic acid amplification test for the rapid diagnosis of Mycobacterium tuberculosis in routine clinical practice.

BACKGROUND: Several nucleic acid amplification (NAA) tests are available for the rapid detection of Mycobacterium tuberculosis (MTB) in clinical specimens. AIMS: To identify the pattern of utilisation and accuracy of the AMPLICOR test in routine clinical practice in an acute care setting. DESIGN: A retrospective descriptive study. METHOD: We studied 159 consecutive specimens in which the AMPLICOR (Roche; Branchburg, NJ) test was requested by attending doctors. The sensitivities and specificities of the AMPLICOR for detection of active tuberculosis (TB) were calculated in relation to types of specimens, smear and culture results. RESULTS: The number of requests more than doubled from 1999 to 2000. Thirty-eight percent of the specimens were not from the respiratory tract. The majority of the specimens had requests for one or more additional test (mean 1.8). The rate of active TB was 18%. The sensitivities of the AMPLICOR on per specimen, per patient, per smear negative specimen and per smear negative patient basis were found to be 81%, 80%, 66.7% and 71.4% respectively. The specificities for these groups accordingly were 99%, 98.6%, 99% and 98.6% respectively. The sensitivity and specificity for respiratory specimens were 97.5% and 98.5%, while for non-respiratory specimens, they were 60% and 100%. In smear negative specimens, the sensitivity and specificity for respiratory specimens were 60% and 98.5%, while for non-respiratory specimens, they were 75% and 100%. The AMPLICOR assay was negative in all 21 specimens of pleural or spinal fluid. CONCLUSIONS: There is a growing demand for NAA in the rapid diagnosis of TB with a high proportion of non-respiratory specimens. The number of additional diagnostic tests performed on each specimen should be limited. In routine clinical practice, the AMPLICOR assay is a useful confirmatory test for active pulmonary TB. The utility of the AMPLICOR assay for MTB detection in exudative fluid specimens needs further evaluation.

Widespread resistance to new antimicrobials in a university hospital before clinical use.

The activity of cefpirome, cefepime and piperacillin/tazobactam previously unused in the hospital was evaluated in parallel with five broad-spectrum antibiotics (ceftazidime, ceftriaxone, imipenem, ciprofloxacin and amikacin) currently being used to treat serious infections in the National University Hospital, Singapore. Two hundred and two clinically significant, organisms consecutively isolated during 1998 were included in the study. In vitro efficacy of cefepime, cefpirome and piperacillin/tazobactam was not superior to imipenem, ciprofloxacin and amikacin which are currently used. More than 40% of Enterbacteriaceae were found to be ESBL producers. The incidence of nosocomial organisms resistant to drugs used in serious infections had increased since 1995. Imipenem-resistance occurred in 34.4% of Acinetobacter spp. and 19.2% Pseudomonas aeruginosa. No single agent appeared to be suitable for empirical monotherapy of serious sepsis.

Endemic typhus in Singapore--a re-emerging infectious disease?

UNLABELLED: Singapore is a modern urban city and endemic typhus is thought to be a disease of the past. This may be due to lack of specific serological testing as indirect immunoperoxidase testing using specific rickettsial antigens (U.S. Army Medical Research Unit, Institute of Medical Research, Kuala Lumpur, Malaysia) has only recently become available. In the last fourteen months, twenty-one cases of endemic typhus were diagnosed in patients hospitalised for acute febrile illnesses at the National University Hospital. We conducted a case control study to define the clinical and laboratory features of endemic typhus in Singapore. METHOD: Demographic, clinical and laboratory data were reviewed for cases and twenty-one age and sex matched controls who had negative serologic tests as part of a work-up for fever of unknown origin. RESULTS: Apart from a higher initial temperature (39 degrees C vs 37.9 degrees C (p < 0.001)) and ALT(p = 0.002), cases and controls had similar presentations of fever, myalgia, headache, cough, normal WBC and platelet counts. Singapore residents and migrant workers were represented in both groups (p = ns). CONCLUSION: Endemic typhus remains an important cause of acute febrile illness in Singaporein both the local and migrant worker populations. The presentation is similar to other causes of acute febrile illnesses and the diagnosis will be missed unless it is specifically sought.

Epidemiological, clinical and laboratory characteristics of 19 serologically confirmed rickettsial disease in Singapore.

AIM: To identify epidemiological, clinical and laboratory features of serologically-proven typhus in the local setting. METHOD & RESULTS: Retrospective study looking at rickettsial serologies done over a six-month period and collection of the epidemological, clinical, laboratory and treatment response data from the case notes of the patients with an ordered rickettsial serology. Twenty of the 35 cases had a positive serology. Of these 20 patients, 18 were already clinically diagnosed as having murine typhus. All except one were males and all were migrant workers. Majority of the patients were construction workers staying in containers where rats abound. The most consistent clinical features were high fever (100%) for a median period of seven days, headache (94%) and cough (47%). The white cell count was usually normal (74%) but thrombocytopenia was common (68%). Transaminitis was also common (90%) with the AST component higher than the ALT in half of the cases. Response to doxycycline therapy was rapid and most (88%) were afebrile by 72 hours. CONCLUSION: Typhus (notably murine type) can be confidently diagnosed from consistent clinical features supported by epidemiological and laboratory clues. Early recognition with the prompt treatment response will result in shorter hospital stay with decreased cost. Serological testing may only prove useful in difficult situations when the clinical diagnosis is less clear.

Relationship between estimated pretest probability and accuracy of automated Mycobacterium tuberculosis assay in smear-negative pulmonary tuberculosis.

BACKGROUND: The AMPLICOR assay (Roche; Branchburg, NJ), a rapid direct amplification test for Mycobacterium tuberculosis, has only been licensed for use in smear-positive respiratory specimens. However, many patients with pulmonary tuberculosis (PTB) have smear-negative disease. The clinical utility of this test in patients with smear-negative PTB is unknown. OBJECTIVE: To evaluate the effect of pretest probability of PTB estimated by chest physicians on the accuracy of the AMPLICOR assay in patients with smear-negative PTB. DESIGN AND METHODS: A prospective study of consecutive patients suspected of having smear-negative PTB. Two chest physicians estimated the pretest probability of active disease (high, intermediate, and low categories). Respiratory specimens were examined with radiometric broth medium cultures and with the AMPLICOR assay for M tuberculosis. The decision on a final diagnosis of PTB was blinded to the AMPLICOR results. RESULTS: Active PTB was diagnosed in 25 of 441 patients (5.7%). The AMPLICOR assay had an overall sensitivity of 44% and a specificity of 99%. Results of the assay were negative in seven patients with culture-negative PTB. The proportions of patients in the high, intermediate, and low pretest groups were 4.5%, 19.7%, and 75.7%, respectively. The incidence of PTB for each group was 95%, 3.4%, and 0.9%, respectively. The sensitivities of the AMPLICOR assay in the three groups of patients were 47%, 33%, and 33%, respectively, while the specificities were 100%, 98%, and 99%, respectively. CONCLUSIONS: In patients suspected of having smear-negative PTB, the following conclusions were drawn: (1) the incidence of active PTB was low; (2) pretest estimates accurately discriminated between patients with high and low risk of PTB; (3) the risk of PTB was overestimated in the intermediate group; and (4) the utility of the AMPLICOR assay in the intermediate-risk group may be limited by the overestimation of disease prevalence and low test sensitivity. Further studies are needed on the role of the AMPLICOR assay in better selected patients with an intermediate risk of having smear-negative PTB.

Invasive Haemophilus influenzae type b infections in Singapore children: a hospital-based study.

OBJECTIVE: A 6-year (1990-95) hospital-based retrospective study was carried out to investigate the pattern of invasive Haemophilus influenzae type b (Hib) disease. METHODOLOGY: Cases with Hib isolated from sterile sites (blood, cerebrospinal fluid, or joint aspirate) were identified from the hospital's microbiological records, and their reviewed case records. Patients with pyogenic meningitis in the same study period were also identified to estimate the incidence of Hib meningitis. RESULTS: Twelve patients had positive cultures from sterile sites, of whom nine children were less than 5 years of age. These included seven cases of meningitis, one patient with acute epiglottitis, and one case of pneumonia. Three of the seven patients with meningitis had significant long-term sequelae. Our data also suggests a relatively low proportion of ethnic Chinese children with invasive disease. It was estimated that 18.4% to 41.1% of pyogenic meningitis in children admitted to the National University Hospital were due to Hib. The estimated annual attack rate of invasive Hib disease was at most 3.3 per 100 000 children aged less than 5 years (95% confidence interval: 2.6-3.5/100 000). CONCLUSION: : Invasive Hib infections are relatively uncommon in our community. This justifies the need for a cost effectiveness study before a universal Hib vaccination program is implemented.

Dissemination of respiratory secretions during tracheal tube suctioning in an intensive care unit.

Most intensive care patients require frequent tracheal toilet, a procedure usually performed by suctioning the tracheal tube. Such procedures often result in the production and dissemination of droplets. We measured the distance visible droplets disseminated during tracheal tube suctioning of patients in an adult surgical intensive care unit. Fifty consecutive suction procedures in 14 patients intubated with a cuffed tracheal tube were investigated. Visible droplets were scattered over a mean distance of 60 +/- 39 cm (range 25 to 168 cm) from the tracheal tube. Blood agar culture plates were placed at three fixed points from the tracheal tube to identify organisms resulting from environmental contamination (control plates). This was repeated during suctioning procedures (study plates) to look into the occurrence of bacteriological cultures that differ from the control plates. Nine of the 14 patients had tracheal tube aspirate cultures done as part of their work-up for sepsis. In more than 30% of the suctioning procedures on these 9 patients, study plates grew bacteria that were similar to those present in their tracheal tube aspirates. In view of these observations, greater care should be taken to avoid contamination of the patient's immediate environment during tracheal tube suctioning and in the design of the intensive care unit.

Seasonal trends of viral respiratory tract infections in the tropics.

To evaluate the seasonal trends of viral respiratory tract infections in a tropical environment, a retrospective survey of laboratory virus isolation, serology and immunofluorescence microscopy in two large general hospitals in Singapore between September 1990 and September 1994 was carried out. Respiratory tract viral outbreaks, particularly among infants who required hospitalization, were found to be associated mainly with respiratory syncytial (RSV) infections (72%), influenza (11%) and parainfluenza viruses (11%). Consistent seasonal variations in viral infections were observed only with RSV (March-August) and influenza A virus (peaks in June, December-January). The RSV trends were associated with higher environmental temperature, lower relative humidity and higher maximal day-to-day temperature variation. Although the influenza A outbreaks were not associated with meteorological factors, influenza B isolates were positively associated with rainfall. These data support the existence of seasonal trends of viral respiratory tract infections in the tropics.

Otitis externa--the clinical pattern in a tertiary institution in Singapore.

Otitis externa is a common condition in the tropics. Most of the data related to the condition have arisen from Western sources. Locally, the aetiology and the pathogens identified have not been systematically studied. A prospective study involving 107 patients was conducted. Otomycosis was frequently encountered. Coagulase negative Staphylococcus and Aspergillus niger were the most common bacteria and fungus cultured respectively. Gentamicin and polymyxin B were the most effective topical agents against Pseudomonas aeruginosa. Self-cleaning of the ears was the most common predisposing factor.

Streptococcus suis infection complicated by purpura fulminans and rhabdomyolysis: case report and review.

Streptococcus suis infection, an important zoonotic occupational disease in humans, is associated with meningitis, arthritis, and perceptive deafness. We report a case of severe S. suis infection in a previously healthy man who developed purpura fulminans and rhabdomyolysis, complications not previously reported with this disease.

In vitro activity of meropenem against organisms causing serious infections in a Singapore hospital.

Meropenem (MEM) is a carbapenem antibiotic effective against infections caused by a variety of organisms. This study was conducted to evaluate MEM, which has not been previously used in the hospital, in parallel with some antimicrobial agents now in use, against organisms causing serious infections in the hospital. A total of 382 organisms isolated from blood cultures were included in the study. In the case of Bacteroides spp. and Burkholderia pseudomallei, organisms recovered from blood as well as from other sites were also included. In addition to MEM, 12 antimicrobial agents were tested against Gram-negative bacilli and seven against staphylococci. Antimicrobial susceptibility testing was carried out by the Kirby-Bauer disc diffusion technique based on the M2-A4 standard. The present paper demonstrates that meropenem, imipenem and ciprofloxacin are the most active antimicrobial agents against clinically important organisms causing serious infections in the hospital.