Fluoroquinolones may delay the diagnosis of tuberculosis

INTRODUCTION

Fluoroquinolones (FQs), frequently used for many common infections such as community-acquired pneumonia and urinary tract infection, are also effective against Mycobacterium tuberculosis. This study describes a series of patients in whom the empirical use of FQs for what appeared to be common community-acquired infections led to a delay in the diagnosis of tuberculosis (TB).

METHODS

We reviewed the records of five patients with TB in whom the early use of FQs led to partial symptom resolution and a prolonged relapsing and remitting course.

RESULTS

Of the five patients described, four presented with community-acquired pneumonia and one with urinary tract infection. All were given FQs and improved, though not completely. Their illnesses took a relapsing and remitting course. TB was eventually diagnosed, in four of them by culture and in one by characteristic histopathology (this patient required surgical resection of a lung abscess).

CONCLUSION

FQs may lead to partial symptom resolution in TB. We highlight the problem of a delayed diagnosis, and voice our concern about inadvertent monotherapy of TB in such cases.

Emergence of community-associated methicillin-resistant Staphylococcus aureus in Singapore: a further six cases

INTRODUCTION

The clinical features and molecular epidemiology of further cases of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection in Singapore are described.

METHODS

Six cases of CA-MRSA infection that occurred between April and October 2004 are described. The bacterial isolates were tested for the presence of Panton-Valentine leukocidin (PVL) genes and typed via pulsedfield gel electrophoresis, staphylococcal chromosomal cassette mec (SCCmec) and multi-locus sequence typing. The results were compared with that of previously-reported local and international CA-MRSA isolates.

RESULTS

There were four cases of cutaneous abscesses and one each of chronic osteomyelitis and endocarditis. CA-MRSA isolates from the last two cases tested negative for PVL genes. Three isolates were identical and related to the Oceanian clone, and one isolate to the predominant Taiwanese clone. The isolate causing osteomyelitis had a novel sequence type.

CONCLUSION

CA-MRSA, though uncommon, is being isolated with increasing frequency in Singapore. A predominant clone (ST30- MRSA-IV) seems to be emerging locally.

Oyster-associated outbreaks of Norovirus gastroenteritis in Singapore

Outbreaks of gastroenteritis associated with the consumption of raw imported half-shelled frozen oysters occurred in Singapore between 16 Dec 2003 and 04 Jan 2004. A total of 305 cases were reported with clinical symptoms of diarrhoea (94%), abdominal cramps (72%), vomiting (69%) and fever (54%). The median incubation period was 30.8h and the duration of illness was 2-3 days. The overall relative risk of oyster consumption was 14.1 (95% CI: 8.3-24.0, P<0.001). Stool and oyster samples tested negative for common bacterial pathogens, including Vibrio parahaemolyticus. However, stool samples were positive for the presence of Norovirus group II RNA via RT PCR while oyster samples indicated the presence of Norovirus particles by electron microscopy. The clinical and epidemiological features were suggestive of Norovirus gastroenteritis and were subsequently confirmed by laboratory tests of stools and implicated oysters. Steps have been taken to ensure that food outlets do not thaw frozen oysters and serve them raw.

Appropriate use of personal protective equipment among healthcare workers in public sector hospitals and primary healthcare polyclinics during the SARS outbreak in Singapore

BACKGROUND

Singapore was affected by an outbreak of severe acute respiratory syndrome (SARS) from 25 February to 31 May 2003, with 238 probable cases and 33 deaths.

AIMS

To study usage of personal protective equipment (PPE) among three groups of healthcare workers (HCWs: doctors, nurses, and administrative staff), to determine if the appropriate PPE were used by the different groups and to examine the factors that may determine inappropriate use.

METHODS

A self-administered questionnaire survey of 14,554 HCWs in nine healthcare settings, which included tertiary care hospitals, community hospitals, and polyclinics, was carried out in May-July 2003. Only doctors, nurses, and clerical staff were selected for subsequent analysis.

RESULTS

A total of 10 236 valid questionnaires were returned (70.3% response); 873 doctors, 4404 nurses, and 921 clerical staff were studied. A total of 32.5% of doctors, 48.7% of nurses, and 77.1% of the administrative staff agreed that paper and/or surgical masks were "useful in protecting from contracting SARS". Among this group, 23.6% of doctors and 42.3% of nurses reported working with SARS patients. The view that a paper and/or surgical mask was adequate protection against SARS was held by 33.3% of doctors and 55.9% of nurses working at the A&E unit, 30.5% of doctors and 49.4% of nurses from medical wards, and 27.5% of doctors and 37.1% of nurses from intensive care units. Factors which predicted for agreement that paper and/or surgical masks were protective against SARS, included HCW's job title, reported contact with SARS patients, area of work, and Impact Events Scale scores.

CONCLUSION

A variety of factors determine appropriate use of personal protective equipment by HCWs in the face of a major SARS outbreak.

Candida spondylodiscitis and epidural abscess: management with shorter courses of anti-fungal therapy in combination with surgical debridement

Epidural abscess associated with candidal spondylodiscitis is rarely seen, particularly when it involves the cervical and thoracic spine. We report two such cases that were successfully managed with early surgical debridement, as well as medical therapy with intravenous amphotericin followed by oral fluconazole. The literature related to candidal spinal infection is reviewed, and a rational approach to the management of this uncommon condition is proposed. A good outcome may generally be expected with early diagnosis as well as appropriate surgical and pharmacological treatment. Oral fluconazole appears to be useful in the management of candida spondylodiscitis complicated by epidural abscess formation. Treatment until a normal ESR is attained is ideal, and this may be as short as 3 months when surgical drainage has been adequately performed.

Cavitating cryptococcal pneumonia in the immunocompetent host

INTRODUCTION

Isolated cryptococcal pneumonia in the immunocompetent host is a rare infection. Indications for treatment and its duration are currently not defined.

CLINICAL PICTURE

Three patients presented with cavitating cryptococcal pneumonia.

TREATMENT

They were treated with oral fluconazole.

OUTCOME

Improvement was evident clinically, radiologically and serologically. Fluconazole was continued until serum cryptococcal antigen (SCA) levels were negative in our patients as they had manifestations such as haemoptysis, cavitating or multi-lobar pneumonia and relatively high antigen levels, suggesting potentially serious disease.

CONCLUSIONS

Fluconazole is effective and safe for the treatment of cryptococcal pneumonia in the immunocompetent host. Although the role of monitoring SCA levels in the immunocompetent host is currently unclear, it may be an indication of infective burden and the benefits of longer treatment seem to outweigh the risks.

Direct identification of Mycobacterium haemophilum in skin lesions of immunocompromised patients by PCR-restriction endonuclease analysis

PCR-restriction endonuclease analysis (PRA) was used for direct identification of Mycobacterium haemophilum in clinical specimens from immunocompromised patients. PRA correctly identified M. haemophilum in four smear-positive specimens. Direct identification by PRA takes 2 to 3 working days compared to the 3 to 5 weeks required for culture isolation and identification by conventional methods.

Bacteremia caused by Gordonia bronchialis in a patient with sequestrated lung

Gordonia species have been recognized as pathogens in immunocompromised and immunocompetent patients. We report the first case of bacteremia due to Gordonia bronchialis in a diabetic patient with a sequestrated lung. Species identification was confirmed with mycolic acid analysis by high-performance liquid chromatography and sequencing of the 16S rRNA gene.

Myocardial infarction in Singapore: a nationwide 10-year study of multiethnic differences in incidence and mortality

INTRODUCTION AND METHODS

Cardiovascular diseases have progressively increased in importance as a major contributor of morbidity and mortality in Asia. However, many countries in Asia do not have nationwide systematically-collected and standardised data on myocardial infarction (MI). To accurately document the extent of atherosclerotic coronary heart disease in Singapore, a nationwide myocardial infarct registry was established in the mid-1986. Possible myocardial infarct events were identified through daily national lists of cardiac enzymes, hospital discharge codes, mortuary records and the national death registry. Data obtained from clinical history, cardiac enzymes and 12-lead electrocardiogram Minnesota codes were entered into an algorithm based on the WHO MONICA study. Cases identified as "definite" MI were included in the decade's review for this study.

RESULTS

From 1988 to 1997, 13,048 myocardial infarct events were diagnosed with 3367 deaths. There was a 39.1% decline in mortality, with an average decline of 6.5% per year [95% confidence intervals (CI), -3.9% to -9.1%]. However, the decline in incidence was only 20.8% with an average decline of 2.4% per year (95% CI, -6.6% to -1.2%). The highest incidence and mortality rates for both genders were seen in the Indians, followed by the Malays and the Chinese.

CONCLUSION

Over 10 years, from 1988 to 1997, we documented a significant fall in mortality from MI in Singapore. There was a smaller decline in the incidence of infarction. Singapore implemented a National Healthy Lifestyle Programme in 1992 as a 10-year effort. The disparity in the incidence and mortality may suggest that a more dramatic and immediate impact has taken place in mortality through therapeutic programmes; primary preventive programmes would be more difficult to evaluate and have a more gradual impact. Only with continual accurate data collection through the whole country, over a much longer period, can the relative value of preventive and therapeutic programmes in coronary heart disease be assessed.

Outcome of percutaneous nephrostomy for the management of pyonephrosis

OBJECTIVE

The aim of this study was to evaluate the efficacy of percutaneous nephrostomy (PCN) drainage for the interim management of pyonephrosis.

METHODS

Ninety-two consecutive patients [29 men, 63 women; mean age, 57 years; range, 23 to 88] who underwent PCN for the treatment of pyonephrosis from 1996 to 1999 were evaluated retrospectively. The clinical presentation, bacteriology and patient outcomes were analyzed.

RESULTS

The majority [77%] of patients had underlying obstructing urinary calculi. Other causes of obstruction included strictures [9%], papillary necrosis [7%], pelvi-ureteric junction obstruction [4%] and malignant stricture [3%]. The microorganisms cultured were Escherichia coli [30%], Klebsiella [19%], Proteus [8%], Pseudomonas [5%], Enterococcus [5%], and Candida spp [5%]. The microorganisms were sensitive to gentamicin [79%], ceftriaxone [71%], cephalexin [54%], nitrofurantoin [40%], cotrimoxazole [35%], nalidixic acid [32%] and ampicillin [29%]. Only 30% of bladder urine cultures were positive for microorganisms; the addition of PCN cultures improved this yield to 58%. The antibiotic regimen was revised according to the PCN culture whenever there was a discrepancy. After PCN, 69% of patients underwent minimally invasive procedures as definitive treatment of the obstructing lesion. Only 14% of patients required open surgery. There was low procedure-related morbidity [14%] and low overall mortality [2%].

CONCLUSIONS

PCN cultures yield important bacteriological information. The procedure is associated with minimal morbidity, facilitates definitive treatment and provides therapeutic benefit.

Birth prevalence of Down syndrome in Singapore from 1993 to 1998

OBJECTIVE

To examine the livebirth prevalence rate of Down Syndrome in Singapore from 1993 to 1998.

DESIGN

Index cases for the National Birth Defects Register were obtained from all neonatal nurseries in Singapore, all hospital discharge summaries, cytogenetic and pathology reports from all pathology laboratories in Singapore and from the compulsory reporting of all termination of pregnancy cases and stillbirths delivered.

SETTING

Information for the Register was obtained from case notes retrieved from the medical record offices, antenatal clinics, cytogenetic laboratories, pathology departments and the Registry of Births and Deaths.

SUBJECTS

All foetuses with Trisomy 21 diagnosed prenatally together with livebirths and stillbirths with Down Syndrome diagnosed at or after birth were identified from the Registry database.

MAIN OUTCOME MEASURES

Prevalence of Down Syndrome

RESULTS

From 1993 to 1998, there were 295 Down Syndrome livebirths, four stillbirths and 197 Down Syndrome foetuses aborted. There has been an increasing number of Down Syndrome foetuses diagnosed antenatally ending in termination and this is accompanied by a falling trend in the Down Syndrome livebirth rate in the same years from 1.17 to 0.89 per 1000 total live births. This is despite an expected increase in Down Syndrome livebirth rate obtained by modelling maternal Down Syndrome age-related risks on the maternal age distribution over the years.

CONCLUSIONS

The livebirth prevalence of Down Syndrome in Singapore has fallen over the years from 1.17/1000 livebirths in 1993 to 0.89/1000 livebirths in 1998 due to antenatal diagnosis and selective termination.

Silica sol-gel for the controlled release of antibiotics. I. Synthesis, characterization, and in vitro release

Room temperature processed silica sol-gel (xerogel) was investigated as a novel controlled release carrier of antibiotics (vancomycin). Xerogel characteristics, in vitro release properties, and bactericidal efficacy of the released antibiotic were determined. The xerogel/vancomycin composite showed a long-term sustained release (up to 6 weeks). In addition, bactericidal efficacy of released vancomycin was retained. The kinetics of release and the amount released were dose dependent. The initial, first-order release was followed by a near-zero-order release. The time to transition from the first- to zero-order release increased with vancomycin load (from 2 to 3 weeks with load increase from 2.2 to 11.1 mg/g). Regardless of the load, about 70% of the original vancomycin content was released by the transitional point, and the cumulative release after 6 weeks of immersion was about 90%. This study, combined with other reports documenting biocompatibility and controlled resorbability of the xerogel/drug composite in vivo, suggests that silica xerogel is a promising controlled release material for the treatment of bone infections.

Traumatic transection of aorta

A 16 year-old man presented with fracture of both his femurs after a road traffic accident. Chest radiograph revealed mediastinal widening. Subsequent CT scan and arch aortogram confirmed the findings of traumatic aortic arch transection at the isthmus. He underwent successful surgical repair. High index of suspicion and prompt actions are important in managing this potentially fatal but treatable condition.

Immunomodulating activity of mycobacterial heat shock protein 65 in tumor cells

In recent years, heat shock proteins have been shown to be effective in enhancing the immunogenicity of tumors. In this study, we examined the effect of mycobacterial hsp65 gene transfection in a non-immunogenic and aggressive tumor cell-line in order to understand the factors that could contribute to the increase in immunogenicity mediated by Hsp65. The transfected cells were found to have indeed lost their tumorigenenicity and increased their immunogenicity. Tumor-specific cytotoxic T cells were present only in mice immunized with the Hsp65-expressing cells. Furthermore, endogenous Hsp70 was significantly increased in irradiated Hsp65-expressing cells and recombinant Hsp65 protein was able to stimulate the mRNA expression of various T helper 1 (Th1) and pro-inflammatory cytokines in splenocyte cultures, as well as a modest expansion of CD4 T cells. These results provide further evidence of the immunomodulating properties of Hsp65, which could be exploited for the treatment of cancer.

Isolation and characterization of group II introns from Pseudomonas alcaligenes and Pseudomonas putida

Group II introns isolated from Pseudomonas alcaligenes NCIB 9867, Pseudomonas putida NCIB 9869, and P. putida KT2440 were closely related with nucleotide sequence identities of between 87 and 96%. The genome of P. alcaligenes also harbored a truncated group II intron of 682 bp that lacks the gene for the intron-encoded protein (IEP). Unlike most bacterial group II introns, the Pseudomonas introns were found to lack the Zn domains in their IEPs, did not appear to interrupt any genes, and were located downstream of open reading frames which were adjacent to hairpin loop structures that resemble rho-independent terminators. These structures also contain the intron binding sites 1 and 2 (IBS1 and IBS2 sequences) that were required for intron target site recognition in transposition. One of the group II introns found in P. alcaligenes, Xln3, was shown to have transposed from the chromosome to the endogenous pRA2 plasmid at a site adjacent to IBS1- and IBS2-like sequences.

RGD tripeptide of bluetongue virus VP7 protein is responsible for core attachment to Culicoides cells

Bluetongue virus (BTV) is an arthropod-borne virus transmitted by Culicoides species to vertebrate hosts. The double-capsid virion is infectious for Culicoides vector and mammalian cells, while the inner core is infectious for only Culicoides-derived cells. The recently determined crystal structure of the BTV core has revealed an accessible RGD motif between amino acids 168 to 170 of the outer core protein VP7, whose structure and position would be consistent with a role in cell entry. To delineate the biological role of the RGD sequence within VP7, we have introduced point mutations in the RGD tripeptide and generated three recombinant baculoviruses, each expressing a mutant derivative of VP7 (VP7-AGD, VP7-ADL, and VP7-AGQ). Each expressed mutant protein was purified, and the oligomeric nature and secondary structure of each was compared with those of the wild-type (wt) VP7 molecule. Each mutant VP7 protein was used to generate empty core-like particles (CLPs) and were shown to be biochemically and morphologically identical to those of wt CLPs. However, when mutant CLPs were used in an in vitro cell binding assay, each showed reduced binding to Culicoides cells compared to wt CLPs. Twelve monoclonal antibodies (MAbs) was generated using purified VP7 or CLPs as a source of antigen and were utilized for epitope mapping with available chimeric VP7 molecules and the RGD mutants. Several MAbs bound to the RGD motif on the core, as shown by immunogold labeling and cryoelectron microscopy. RGD-specific MAb H1.5, but not those directed to other regions of the core, inhibited the binding activity of CLPs to the Culicoides cell surface. Together, these data indicate that the RGD motif present on BTV VP7 is responsible for Culicoides cell binding activity.

Oral biopsy turnaround time: 20-year experience of the Department of Oral Pathology, Oral Medicine and Periodontology, Faculty of Dentistry, University of Malaya

The turnaround time (TAT) for oral biopsies received for histological examination by the Department of Oral Pathology, Oral Medicine and Periodontology, Faculty of Dentistry, University of Malaya, for the years 1978, 1988 and 1998 was evaluated. For the three years studied, TATs for 61, 233 and 463 specimens were retrospectively analysed. Testing intervals, that is, from the dates the surgeons procured the specimens, the laboratories accessioned them and until the pathologists signed off the diagnoses, were used to calculate TAT. The performance level of the respective pathologists, the growth of tissue diagnostic services and the possible variables that influence TAT were also evaluated. As prompt diagnosis means prompt treatment, which in turn has a bearing on prognosis, the TAT pertinent to oral malignant tumors was emphasized. The mean TAT, its mode and median fell significantly in 1998 compared with the previous 2 years; it was lower for soft tissue than for hard tissue specimens, and lower for malignant, than for non-malignant specimens. The progression of tissue diagnostic services is up to a satisfactory level, as 88.89 % of biopsies could render diagnoses within a fair period of time in 1998.

Comparison of quantitative cytomegalovirus (CMV) PCR in plasma and CMV antigenemia assay: clinical utility of the prototype AMPLICOR CMV MONITOR test in transplant recipients

The correlation between the prototype AMPLICOR CMV MONITOR test (Roche Molecular Systems), a quantitative PCR assay, and the cytomegalovirus (CMV) pp65 antigenemia assay was evaluated in transplant recipients. Sequential blood specimens were collected on 29 patients (491 specimens), the leukocyte fraction was tested by CMV antigenemia, and quantitative PCR was performed on plasma specimens. None of the 15 patients (242 specimens) who were antigenemia negative were positive for CMV DNA by PCR, and none of these patients developed active CMV disease. There were 14 antigenemia-positive patients, 8 of whom developed active CMV disease. In all patients, there was a good association between the antigenemia and PCR assays. Ganciclovir-resistant virus was isolated from three patients with active CMV disease. These three patients had persistently elevated levels of antigenemia and CMV DNA by PCR when resistance to ganciclovir developed. This standardized, quantitative CMV PCR assay on plasma has clinical utility for the diagnosis of active disease and in monitoring the response to antiviral therapy in transplant recipients.