Application of a multiplex pbp2b and pbp2x PCR for prediction of penicillin resistance in Streptococcus pneumoniae.
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Aminoacyltransferases↗
Biomedical subjects
P L Ho
Publications and source records attributed to P L Ho.
Genome features of Leptospira interrogans serovar Copenhageni.
We report novel features of the genome sequence of Leptospira interrogans serovar Copenhageni, a highly invasive spirochete. Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in mammals. Genomic sequence analysis reveals the presence of a competent transport system with 13 families of genes encoding for major transporters including a three-member component efflux system compatible with the long-term survival of this organism. The leptospiral genome contains a broad array of genes encoding regulatory system, signal transduction and methyl-accepting chemotaxis proteins, reflecting the organism's ability to respond to diverse environmental stimuli. The identification of a complete set of genes encoding the enzymes for the cobalamin biosynthetic pathway and the novel coding genes related to lipopolysaccharide biosynthesis should bring new light to the study of Leptospira physiology. Genes related to toxins, lipoproteins and several surface-exposed proteins may facilitate a better understanding of the Leptospira pathogenesis and may serve as potential candidates for vaccine.
Animals↗
Comparative genomics of two Leptospira interrogans serovars reveals novel insights into physiology and pathogenesis.
Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide O side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.
Animals↗
Direct detection of rifampin-resistant mycobacterium tuberculosis in respiratory specimens by PCR-DNA sequencing.
This study evaluated the feasibility of a molecular strategy based on identification of Mycobacterium tuberculosis by IS6110 PCR or Cobas Amplicor PCR, and rpoB PCR-DNA sequencing of the 81-bp rifampin resistance determining region (RRDR) for direct detection of rifampin resistance in respiratory specimens. A collection of 2,138 respiratory specimens and 352 nonduplicate M. tuberculosis isolates (including 233 isolates from the evaluated respiratory specimens and an additional collection of 119 stored isolates) from Southern China was investigated. Using culture as the reference test, the overall diagnostic sensitivities of an acid-fast bacillus (AFB) smear, Cobas Amplicor PCR, IS6110 PCR were 54.5% (156 of 286), 86.7% (248 of 286), and 89.2% (255 of 286), respectively. The sensitivities of the rpoB PCR for the specimens with positive AFB smears and with positive PCR results in the IS6110 PCR and/or Cobas Amplicor PCR were 100% (156 of 156) and 92.3% (239 of 259), respectively. Of the 352 nonduplicate M. tuberculosis isolates, the agar proportion method for rifampin reported 39 resistant strains. Full agreement (352 of 352) was found with the agar proportion method and the genotype inferred from the rpoB DNA sequencing data for rifampin. Thirty-nine mutations of nine distinct kinds, eight point mutations, and one deletion within the RRDR were found in the 39 resistant strains. For the direct DNA sequencing performed on rpoB PCR-positive respiratory specimens, the concordance with the agar proportion method and the subsequent PCR-sequencing for the culture isolate was 100%. This strategy has potential application for direct and rapid diagnosis of rifampin-resistant M. tuberculosis in IS6110 PCR or Cobas Amplicor PCR-positive respiratory specimens.
Antibiotics, Antitubercular↗
Diagnosis and pharmacotherapy of severe acute respiratory syndrome: what have we learnt?
In 2003, the onset of severe acute respiratory syndrome (SARS) caused worldwide chaos. Although SARS was eradicated by isolation towards the end of 2003, sporadic cases have been reported in Singapore, Taiwan and mainland China. In this review, SARS is discussed as a disease, as well as its diagnosis, management and pharmacotherapy. Respiratory physicians and healthcare professionals have to be aware of advances in the understanding of the diagnosis and management of severe acute respiratory syndrome. More research is required in order to prepare for if this respiratory infection recurs, but there are concerns that adequate pharmaceutical support may be lacking for the development of a vaccine.
Anti-Bacterial Agents↗
Pentaglobin in steroid-resistant severe acute respiratory syndrome.
SETTING: The treatment of severe acute respiratory syndrome (SARS) is at best controversial, although there is considerable anecdotal experience to show the benefits of corticosteroid therapy for selected patients. Some patients deteriorate relentlessly despite treatment with antibiotic, corticosteroid and mechanical ventilation. OBJECTIVE: To attempt to determine the clinical efficacy of pentaglobin, an IgM-enriched immunoglobulin preparation, on 12 severe SARS patients who continued to deteriorate despite corticosteroid and ribavirin therapy. DESIGN: Retrospective analysis of daily quantitative and radiographic data on the cohort in a regional teaching hospital. RESULTS AND CONCLUSION: There was significant improvement in radiographic scores, when compared with day 1, on days 5, 6 and 7 (P < 0.05) after commencement of pentaglobin treatment. Similarly, there was significant improvement in oxygen requirement, when compared with day 1, on days 6 and 7 (P < 0.05) after commencement of pentaglobin treatment. There were no reported adverse events attributable to pentaglobin administration. Ten patients made an uneventful recovery after treatment. One elderly man died from cardiorespiratory arrest despite clinical and radiological improvement, and another patient is making good progress. Pentaglobin is safe and probably effective in the treatment of steroid-resistant SARS. A double-blind placebo-controlled study should therefore be considered.
Adrenal Cortex Hormones↗
Exhaled nitric oxide in bronchiectasis: the effects of inhaled corticosteroid therapy.
SETTING: While exhaled nitric oxide (eNO) levels are reduced by inhaled corticosteroid therapy in asthma, such treatment effect is unclear in bronchiectasis. DESIGN: Stable non-smoking bronchiectasis patients were randomised to receive either fluticasone (1 mg/daily) or identical placebo via the Accuhaler device. RESULTS: Sixty non-smoking patients (38 women; mean age 56.4 +/- 12.7 years) were recruited. Of these, half received inhaled fluticasone and half placebo therapy. eNO was measured using a chemiluminescence analyser at 0, 4, 12, 24, 36 and 52 weeks. There was no significant difference in eNO levels between fluticasone and placebo patients over the study period. There was no correlation between baseline eNO with age, FEV1, FVC, 24 h sputum volume or number of bronchiectatic segments. Patients with Pseudomonas aeruginosa (PA) infection, but not their counterparts, displayed a correlation between 0- and 52-week eNO levels. PA infection was associated with significantly lower eNO levels among the patients. CONCLUSIONS: Inhaled fluticasone therapy, despite being an effective anti-inflammatory agent, has no significant effect on eNO production, either at individual time points or over the entire 52-week profile, in bronchiectasis. It appears that eNO might not reflect the extent of airway inflammation in bronchiectasis.
Administration, Inhalation↗
Continuous ambulatory peritoneal dialysis-related peritonitis caused by Streptococcus bovis.
The first case of Streptococcus bovis peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD) in a 40-year-old Chinese woman suffering from systemic lupus erythematosus is reported. Streptococcus bovis is part of the normal flora in the human intestine and, less commonly, the female genital tract. Being a rare cause of peritonitis, the possible link between genital tract colonization by Streptococcus bovis and retrograde invasion of the peritoneal cavity is postulated to be the cause of continuous ambulatory peritoneal dialysis peritonitis in this patient. Since invasive Streptococcus bovis infection is associated with gastrointestinal pathology (Streptococcus bovis biotype I) and chronic liver diseases (Streptococcus bovis biotype II), identifying the biotype of Streptococcus bovis could guide treatment by indicating that further investigation of these underlying diseases is required.
Adult↗
Chronic renal insufficiency in children: the 2001 Annual Report of the NAPRTCS.
End-stage renal disease (ESRD) is a major cause of morbidity in children. Besides its high cost to society, ESRD carries significant mortality. Chronic renal insufficiency (CRI) often precedes ESRD. Identifying factors that correlate with the rate of progression to ESRD is beneficial in the management of children with CRI. Since 1994 the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) has extended its registry to include children with CRI, defined as creatinine clearance ( C(Cr)) <75 ml/min per 1.73 m(2). As of January 2001, our database registered 4,666 children (<20 years of age) with CRI. Data analysis showed that at least 40% of patients entered had congenital urological anomalies; 39% of patients were followed for at least 3 years. Follow-up data showed that 31% of all registered patients progressed to ESRD by the end of the reporting period. There was a correlation between CRI and several co-morbid clinical factors: low hematocrit, hypoalbuminemia, hypocalcemia, hyperphosphatemia, and hyperparathyroidism, and the rate of progression to ESRD. Primary clinical diagnosis and the age at entry into registry were additional factors that correlated with the rate of progression to ESRD. The main cause of hospitalization in this registry was infection, which accounted for 45% of hospital admissions. Growth delay measured by standard deviation score at baseline was -1.40 at the time of registration. Our data suggest potential areas of improved care that could impact the onset of ESRD.
Acidosis↗
Three-year study of targeted screening for methicillin-resistant Staphylococcus aureus at hospital admission.
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Carrier State↗
Changing trends in pediatric transplantation: 2001 Annual Report of the North American Pediatric Renal Transplant Cooperative Study.
The North American Pediatric Renal Transplant Cooperative Study has collected clinical information on children undergoing a renal transplantation since 1987. This cooperative group now includes over 150 participating medical centers in the United States, Canada, Mexico, and Costa Rica. This report covers the years from 1987 through 2001 and includes data on 7545 renal transplants in 6878 patients. This report demonstrates changing trends in many areas of pediatric transplantation including increasing numbers of African American and Hispanic children receiving transplantation, remarkable improvements in the rate of acute rejection, rejection reversal, and short- and long-term allograft survival. In the most recent cohorts of patients, we now see that 1-yr allograft survival is no different in cadaver donor compared to living donor recipients and in infants compared to all other age groups. However, this analysis also reveals areas of continued challenges including inferior outcomes in African American and adolescent populations, chronic rejection, and the adverse effects of immunosuppression.
Black People↗
Nontuberculous mycobacterial infections in Chinese hematopoietic stem cell transplantation recipients.
Between 1995 and 2002, nine cases of nontuberculous mycobacterium (NTM) were isolated from 462 allogeneic stem cell transplant (SCT) recipients (1.9%), and none from 139 autologous cases. They included three cases each of Mycobacterium fortuitum and M. chelonae, and single cases of M. scrofalaceum, M. gordonnae and M. avium complex. Seven cases were respiratory, including five cases requiring treatment, and two involved infected catheters and vascular conduits. Compared with nine cases of mycobacterium tuberculosis (MTB) isolated in the same period, NTM isolation occurred later after HSCT and involved more unrelated donors. Important risk factors for NTM infection included significant aGVHD (P=0.043), leukemia relapse (P=0.022), MUD and mismatch SCT (P<0.001) and existence of BO (P<0.001). Coinfection with aspergillus was common. Invasive NTM disease required prolonged antimicrobial treatment in five cases due to M. fortuitum and M. chelonae. With better MTB prophylaxis, intensive immunosuppression and better awareness, NTM has become an emerging threat in oriental allogeneic HSCT recipients. The cutoff between colonization and infection, and the threshold for starting treatment is unclear. NTM isolation is a marker for severe immunosuppression and poor prognosis. When there is doubt over species identity or extent of infection, broad-spectrum cover may be prudent.
Adult↗
Estimation of bacterial risk in extending the shelf life of PLT concentrates from 5 to 7 days.
BACKGROUND: The use of bacterial culture to prevent bacterial contamination of blood components has renewed interest for extending the shelf life of PLT concentrates to 7 days after collection. STUDY DESIGN AND METHODS: This study was therefore conducted to determine the residual risk of bacterial contamination in PLT concentrates at the end of 5 and 7 days after collection in a center where all PLT concentrates are routinely screened by taking samples on Day 2 for culture. PLT units with no growth after 48 hours were sampled a second time on Day 5 or Day 7 after collection, followed by inoculation into aerobic culture bottles. The inoculated bottles were then monitored for up to 7 days at 35 degrees C in an automatic monitoring and detection system. RESULTS: During a 16-month study period, a total of 6020 PLT concentrates were tested 5 days (Group A, n=3010) and 7 days (Group B, n=3010) after collection. Four units in each group (0.133%) were found to be contaminated. In 6 units, bacteria were seen on direct Gram stain. In addition, 5 of the associated RBC units grew the same organisms on culture. The organisms include three coagulase-negative staphylococci and five Propionibacterium acnes. The positive rate of routine short-term bacterial culture was 0.035 percent during the same study period. CONCLUSION: Despite routine short-term bacterial culture, a significant risk of bacterial contamination remains at 5 and 7 days after collection. For now, the shelf life of PLT concentrates should remain 5 days.
Bacteria↗
Epidemiologic analysis of invasive and noninvasive group a streptococcal isolates in Hong Kong.
Since the mid-1980s, there has been a resurgence of severe forms of invasive group A streptococcal (GAS) disease in many Western countries. In Hong Kong, a similar increase has also been observed in recent years. One hundred seven GAS isolates collected from 1995 to 1998 from individuals with necrotizing fasciitis, toxic shock syndrome, meningitis, or other type of bacteremic sepsis (invasive group, n = 24) as well as from individuals with minor skin and throat infections (noninvasive group, n = 83) were characterized through serologic and/or emm sequence typing. Thirty-two M protein gene sequence types were identified. Types M1, M4, and M12 were the most prevalent in both the invasive group and the noninvasive group; together they accounted for 70.8 and 37.3% of the isolates, respectively. No clear pattern of skin and throat infection M types was observed. Type M1 was overrepresented in the invasive and pharyngeal isolates. The same pulsed-field gel electrophoresis pattern was shared by most invasive and all pharyngeal M1 isolates. Overall, resistance to erythromycin (32%) and tetracycline (53%) was high, but M1 isolates were significantly less likely to have resistance to either antimicrobial agent than non-M1 isolates. One novel emm sequence type, stHK, was identified in an isolate from a patient with necrotizing fasciitis. Minor emm gene sequence alterations were noted for 31 isolates, and for 13 of these isolates, deletion, insertion, or point mutations were seen in the hypervariable 50 N-terminal residues.
Amino Acid Sequence↗
Multiple brain abscesses in a patient with bilateral pulmonary arteriovenous malformations and immunoglobulin deficiency.
A 34 year old Chinese man presented with grand mal seizures complicating multiple brain abscesses caused by mixed oral flora. Because of persistent hypoxaemia contrast spiral thoracic computed tomography was done, which revealed bilateral pulmonary arteriovenous malformations (PAVMs). Concomitant IgA and IgG subclass deficiency was also found. The combination of these two conditions appears to have predisposed this patient to presumably paradoxical septic embolism. The patient's cerebral condition responded to postoperative antibiotic treatment and he eventually received selective coil embolisation of right lower lobe PAVMs, which relieved his hypoxaemia and dyspnoea.
Adult↗
Effects of erythromycin on Pseudomonas aeruginosa adherence to collagen and morphology in vitro.
The airways of patients with bronchiectasis and cystic fibrosis are often chronically colonised by Pseudomonas aeruginosa (PA), which is virtually impossible to eradicate. Low-dose erythromycin (EM), for unknown mechanisms, is efficacious in bronchiectasis and diffuse panbronchiolitis. In this study, an in vitro model to investigate PA adherence to human type IV basement collagen was developed by using scanning electron microscopy (SEM). There were significantly less PA bacilli per 20 random SEM fields (4,000x) when PA was cultured in 0.05, 0.5 and 5 microg x mL(-1) of EM compared with control (absence of EM). Adherence density (20 SEM fields x log(-1) inocular size) for PA obtained from no EM (56.8 +/- 43.16) was significantly higher than that obtained from 0.05, 0.5, and 5 microg x mL(-1) EM (21.5 +/- 17.56, 23.3 +/- 16.65, and 21.4 +/- 12.65 respectively). By using SEM it was found that PA, when incubated in EM (0.05, 0.5, 5 microg x mL(-1)) had a significant reduction in its diagonal length, radius, height, volume and surface area. It is possible, therefore, that these misshaped Pseudomonas aeruginosa bacilli are more susceptible to host defence mechanisms, while at the same time less adherent to the basement membrane of the airway in vivo. Therefore, this could help explain the clinical efficacy of low-dose erythromycin therapy on patients with Pseudomonas aeoruginosa infection.
Bacterial Adhesion↗
Tuberculous meningitis with tuberculomata presenting as postpartum pyrexia of unknown origin.
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Adult↗
Disseminated ochroconis gallopavum infection in a renal transplant recipient: the first reported case and a review of the literature.
Ochroconis gallopavum is a potentially fatal dematiaceous fungus causing opportunistic infections in immunocompromised hosts. We report the first case of disseminated O. gallopavum infection in a 13-year-old renal transplant recipient, which involved the brain, lung and spleen. He was treated with amphotericin B, itraconazole and voriconazole, a new antifungal agent first used to treat such an infection. Besides antifungal treatment, all immunosuppressive agents were stopped and automated peritoneal dialysis was resumed. The initial infection was under control with both clinical and radiological improvements after treatment. However, the patient later acquired Acremonium spp. peritonitis; he failed to respond to high-dose amphotericin B, and finally succumbed. A total of 13 reported O. gallopavum human infections, including the one described here, are reviewed. The most common site of involvement is the brain and the crude mortality rate is up to 46%. As the disease is potentially lethal in immunocompromised hosts, empirical antifungal coverage should be considered in post-renal transplant recipients with suspected brain abscess. Early biopsy of lesion for histopathological and microbiological diagnosis would be essential in managing such cases.
Adolescent↗