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1.  Multi-Serotype Pneumococcal Nasopharyngeal Carriage Prevalence in Vaccine Naïve Nepalese Children, Assessed Using Molecular Serotyping 
PLoS ONE  2015;10(2):e0114286.
Invasive pneumococcal disease is one of the major causes of death in young children in resource poor countries. Nasopharyngeal carriage studies provide insight into the local prevalence of circulating pneumococcal serotypes. There are very few data on the concurrent carriage of multiple pneumococcal serotypes. This study aimed to identify the prevalence and serotype distribution of pneumococci carried in the nasopharynx of young healthy Nepalese children prior to the introduction of a pneumococcal conjugate vaccine using a microarray-based molecular serotyping method capable of detecting multi-serotype carriage. We conducted a cross-sectional study of healthy children aged 6 weeks to 24 months from the Kathmandu Valley, Nepal between May and October 2012. Nasopharyngeal swabs were frozen and subsequently plated on selective culture media. DNA extracts of plate sweeps of pneumococcal colonies from these cultures were analysed using a molecular serotyping microarray capable of detecting relative abundance of multiple pneumococcal serotypes. 600 children were enrolled into the study: 199 aged 6 weeks to <6 months, 202 aged 6 months to < 12 months, and 199 aged 12 month to 24 months. Typeable pneumococci were identified in 297/600 (49·5%) of samples with more than one serotype being found in 67/297 (20·2%) of these samples. The serotypes covered by the thirteen-valent pneumococcal conjugate vaccine were identified in 44·4% of samples containing typeable pneumococci. Application of a molecular serotyping approach to identification of multiple pneumococcal carriage demonstrates a substantial prevalence of co-colonisation. Continued surveillance utilising this approach following the introduction of routine use of pneumococcal conjugate vaccinates in infants will provide a more accurate understanding of vaccine efficacy against carriage and a better understanding of the dynamics of subsequent serotype and genotype replacement.
PMCID: PMC4313945  PMID: 25643355
3.  Streptococcus pneumoniae Carriage Prevalence in Nepal: Evaluation of a Method for Delayed Transport of Samples from Remote Regions and Implications for Vaccine Implementation 
PLoS ONE  2014;9(6):e98739.
Pneumococcal disease is a significant cause of morbidity and mortality in young children in Nepal, and currently available pneumococcal conjugate vaccines offer moderate coverage of invasive disease isolates.
A prevalence study of children aged 1.5 to 24 months in urban and rural Nepal was conducted. In the urban group, nasopharyngeal swabs (NPS) were transported using silica desiccant packages (SDP) with delayed processing (2 weeks), or skim-milk-tryptone-glucose-glycerin (STGG) with immediate processing (within 8 hours). Pneumococcal nasopharyngeal carriage prevalence, serogroup/type distribution and isolate genotypes (as defined by multilocus sequence typing) were determined.
1101 children were enrolled into the study: 574 in the urban group and 527 in the rural group. Overall carriage prevalence based on culture from specimens transported and stored in STGG was 58.7% (337/574), compared to 40.9% (235/574) in SDP. There was concordance of detection of pneumococcus in 67% of samples. Using the SDP method, pneumococcal carriage prevalence was higher in the rural population (69.2%; 364/526) compared to the urban population (40.9%; 235/574). Serogroup/type distribution varied with geographical location. Over half of the genotypes identified in both the urban and rural pneumococcal populations were novel.
The combination of delayed culture and transport using SDP underestimates the prevalence of pneumococcal carriage; however, in remote areas, this method could still provide a useful estimate of carriage prevalence and serogroup/type distribution. Vaccine impact is unpredictable in a setting with novel genotypes and limited serotype coverage as described here. Consequently, continued surveillance of pneumococcal isolates from carriage and disease in Nepali children following the planned introduction of pneumococcal conjugate vaccines introduction will be essential.
PMCID: PMC4048273  PMID: 24905574
4.  Biomarkers of Cardiac Dysfunction and Mortality from Community-Acquired Pneumonia in Adults 
PLoS ONE  2013;8(5):e62612.
Cardiac dysfunction is common in acute respiratory diseases and may influence prognosis. We hypothesised that blood levels of N-terminal B-type natriuretic peptide (NT-proBNP) and high-sensitivity Troponin T would predict mortality in adults with community-acquired pneumonia.
Methods and Findings
A prospective cohort of 474 consecutive patients admitted with community-acquired pneumonia to two New Zealand hospitals over one year. Blood taken on admission was available for 453 patients and was analysed for NT-proBNP and Troponin T. Elevated levels of NT-proBNP (>220 pmol/L) were present in 148 (33%) and 86 (19%) of these patients respectively. Among the 26 patients who died within 30 days of admission, 23 (89%) had a raised NT-proBNP and 14 (53%) had a raised Troponin T level on admission compared to 125 (29%) and 72 (17%) of the 427 who survived (p values<0.001). Both NT-proBNP and Troponin T predicted 30-day mortality in age-adjusted analysis but after mutual adjustment for the other cardiac biomarker and the Pneumonia Severity Index, a raised N-terminal pro-brain natriuretic peptide remained a predictor of 30-day mortality (OR = 5.3, 95% CI 1.4–19.8, p = 0.013) but Troponin T did not (OR = 1.3, 95% CI 0.5–3.2, p = 0.630). The areas under the receiver-operating curves to predict 30-day mortality were similar for NT-proBNP (0.88) and the Pneumonia Severity Index (0.87).
Elevated N-terminal B-type natriuretic peptide is a strong predictor of mortality from community-acquired pneumonia independent of clinical prognostic indicators. The pathophysiological basis for this is unknown but suggests that cardiac involvement may be an under-recognised determinant of outcome in pneumonia and may require a different approach to treatment. In the meantime, measurement of B-type natriuretic peptides may help to assess prognosis.
PMCID: PMC3646835  PMID: 23667500
5.  Clinical Presentation, Etiology and Outcome of Infective Endocarditis in the 21st Century: The International Collaboration on Endocarditis-Prospective Cohort Study 
Archives of internal medicine  2009;169(5):463-473.
The aim of this study was to provide a contemporary picture of the presentation, etiology and outcome of infective endocarditis (IE) in a large patient cohort from multiple locations worldwide.
Prospective cohort study of 2781 adults with definite IE admitted to 58 hospitals in 25 countries between June 2000 and September 2005.
The median age of the cohort was 57.9 (IQR 43.2–71.8) years and 72% had native valve IE. Most (77%) patients presented early in the disease (<30 days) with few of the classic clinical hallmarks of IE. Recent health-care exposure was found in one quarter of patients. Staphylococcus aureus was the most common pathogen (31%). Mitral (41%) and aortic (38%) valves were infected most commonly. Complications were common: stroke (17%); embolization other than stroke (23%); heart failure (32%) and intracardiac abscess (14%). Surgical therapy was common (48%) and in-hospital mortality remained high (18%). Prosthetic valve involvement (OR 1.47, 95%CI 1.13–1.90), increasing age (OR 1.30, 95%CI 1.17–1.46 per 10-year interval), pulmonary edema (OR 1.79, 95%CI 1.39–2.30), S. aureus infection (OR 1.54, 95%CI 1.14–2.08), coagulase-negative staphylococcal infection (OR 1.50, 95%CI 1.07–2.10), mitral valve vegetation (OR 1.34, 95%CI 1.06–1.68), and paravalvular complications (OR 2.25, 95%CI 1.64–3.09) were associated with increased risk of in-hospital death, while viridans streptococcal infection (OR 0.52, 95%CI 0.33–0.81) and surgery (OR 0.61, 95%CI 0.44–0.83) were associated with decreased risk.
In the early 21st century, IE is more often an acute disease, characterized by a high rate of S. aureus infection. Mortality remains relatively high.
PMCID: PMC3625651  PMID: 19273776
6.  Use and Evaluation of Molecular Diagnostics for Pneumonia Etiology Studies 
Comprehensive microbiological testing will be a core function of the Pneumonia Etiology Research for Child Health (PERCH) project. The development stage of PERCH provided the time and resources necessary for us to conduct a comprehensive review of the current state of respiratory diagnostics. These efforts allowed us to articulate the unique requirements of PERCH, establish that molecular methods would be central to our testing strategy, and focus on a short list of candidate platforms. This process also highlighted critical challenges in the general design and interpretation of diagnostic evaluation studies, particularly in the field of respiratory infections. Although our final molecular diagnostic platform was ultimately selected on the basis of operational and strategic considerations determined by the specific context of PERCH, our review highlighted several conceptual and practical challenges in respiratory diagnostics that have broader relevance for the performance and interpretation of pneumonia research studies.
PMCID: PMC3297547  PMID: 22403230
7.  The Role of Postmortem Studies in Pneumonia Etiology Research 
The diagnosis of etiology in severe pneumonia remains a challenging area. Postmortem lung tissue potentially increases the sensitivity of investigations for identification of causative pathogens in fatal cases of pneumonia and can confirm antemortem microbiological diagnoses. Tissue sampling allows assessment of histological patterns of disease and ancillary immunohistochemical or molecular diagnostic techniques. It may also enhance the recognition of noninfectious conditions that clinically simulate acute pneumonia. Biobanking of lung tissue or postmortem culture isolates offers opportunities for new pathogen discovery and research into host-pathogen interactions. The Pneumonia Etiology Research for Child Health study proposes a percutaneous needle biopsy approach to obtain postmortem samples, rather than a full open autopsy. This has the advantage of greater acceptability to relatives, but risks greater sampling error. Both approaches may be susceptible to microbiological contamination or pathogen degradation. However, previous autopsy studies have confirmed the value of histological examination in revealing unsuspected pathogens and influencing clinical guidelines for the diagnosis and treatment of future pneumonia cases.
PMCID: PMC3297548  PMID: 22403232
8.  Bioethical Considerations in Developing a Biorepository for the Pneumonia Etiology Research for Child Health Project 
The Pneumonia Etiology Research for Child Health (PERCH) project has the potential to provide a highly valuable resource of biospecimens that may be used to inform future studies on the causes of pneumonia. Designing a biorepository for this complex project was done in collaboration with a wide range of experts including bioethicists. In this paper, we describe the most significant ethical issues encountered related to the biorepository, focusing on its structure and informed consent. We also outline the proposed approach to the PERCH biorepository, which was designed to be sensitive to the ethical, practical, and cultural challenges inherent to the study. Through this process, we concluded that biorepository governance plans and strategies for managing informed consent should be implemented in a way to allow for careful study in order to better understand the attitudes of and impact on the stakeholders involved in the study.
PMCID: PMC3297549  PMID: 22403233
9.  Evaluation of Risk Factors for Severe Pneumonia in Children: The Pneumonia Etiology Research for Child Health Study 
As a case-control study of etiology, the Pneumonia Etiology Research for Child Health (PERCH) project also provides an opportunity to assess the risk factors for severe pneumonia in hospitalized children at 7 sites. We identified relevant risk factors by literature review and iterative expert consultation. Decisions for inclusion in PERCH were based on comparability to published data, analytic plans, data collection costs and logistic feasibility, including interviewer time and subject fatigue. We aimed to standardize questions at all sites, but significant variation in the economic, cultural, and geographic characteristics of sites made it difficult to obtain this objective. Despite these challenges, the depth of the evaluation of multiple risk factors across the breadth of the PERCH sites should furnish new and valuable information about the major risk factors for childhood severe and very severe pneumonia, including risk factors for pneumonia caused by specific etiologies, in developing countries.
PMCID: PMC3297552  PMID: 22403226
10.  Procedures for Collection of Induced Sputum Specimens From Children 
In most settings, sputum is not routinely collected for microbiological diagnosis from children with lower respiratory disease. To evaluate whether it is feasible and diagnostically useful to collect sputum in the Pneumonia Etiology Research for Child Health (PERCH) study, we reviewed the literature on induced sputum procedures. Protocols for induced sputum in children were collated from published reports and experts on respiratory disease and reviewed by an external advisory group for recommendation in the PERCH study. The advisory group compared 6 protocols: 4 followed a nebulization technique using hypertonic saline, and 2 followed a chest or abdomen massage technique. Grading systems for specimen quality were evaluated. Collecting sputum from children with lower respiratory tract illness is feasible and is performed around the world. An external advisory group recommended that sputum be collected from children hospitalized with severe and very severe pneumonia who participate in the PERCH study provided no contraindications exist. PERCH selected the nebulization technique using hypertonic saline.
PMCID: PMC3297553  PMID: 22403228
11.  A Preliminary Study of Pneumonia Etiology Among Hospitalized Children in Kenya 
Background. Pneumonia is the leading cause of childhood death in the developing world. Higher-quality etiological data are required to reduce this mortality burden.
Methods. We conducted a case-control study of pneumonia etiology among children aged 1–59 months in rural Kenya. Case patients were hospitalized with World Health Organization–defined severe pneumonia (SP) or very severe pneumonia (VSP); controls were outpatient children without pneumonia. We collected blood for culture, induced sputum for culture and multiplex polymerase chain reaction (PCR), and obtained oropharyngeal swab specimens for multiplex PCR from case patients, and serum for serology and nasopharyngeal swab specimens for multiplex PCR from case patients and controls.
Results. Of 984 eligible case patients, 810 (84%) were enrolled in the study; 232 (29%) had VSP. Blood cultures were positive in 52 of 749 case patients (7%). A predominant potential pathogen was identified in sputum culture in 70 of 417 case patients (17%). A respiratory virus was detected by PCR from nasopharyngeal swab specimens in 486 of 805 case patients (60%) and 172 of 369 controls (47%). Only respiratory syncytial virus (RSV) showed a statistically significant association between virus detection in the nasopharynx and pneumonia hospitalization (odds ratio, 12.5; 95% confidence interval, 3.1–51.5). Among 257 case patients in whom all specimens (excluding serum specimens) were collected, bacteria were identified in 24 (9%), viruses in 137 (53%), mixed viral and bacterial infection in 39 (15%), and no pathogen in 57 (22%); bacterial causes outnumbered viral causes when the results of the case-control analysis were considered.
Conclusions. A potential etiology was detected in >75% of children admitted with SP or VSP. Except for RSV, the case-control analysis did not detect an association between viral detection in the nasopharynx and hospitalization for pneumonia.
PMCID: PMC3297554  PMID: 22403235
12.  Heterogeneous Vancomycin-Intermediate Susceptibility Phenotype in Bloodstream Methicillin-Resistant Staphylococcus aureus Isolates from an International Cohort of Patients with Infective Endocarditis: Prevalence, Genotype, and Clinical Significance 
The Journal of infectious diseases  2009;200(9):1355-1366.
The significance of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) is unknown. Using a multinational collection of isolates from methicillin-resistant S. aureus (MRSA) infective endocarditis (IE), we characterized IE patients with and without hVISA, and genotyped the infecting strains.
MRSA bloodstream isolates from 65 patients with definite IE from 8 countries underwent PCR for 31 virulence genes, pulsed-field gel electrophoresis, and multilocus sequence typing. hVISA was defined using population analysis profiling (PAP).
Nineteen (29.2%) of 65 MRSA IE isolates exhibited hVISA by PAP. Isolates from Oceania and Europe were more likely to exhibit hVISA than isolates from the United States (77.8% vs. 35.0% vs. 13.9%; P < .001). The prevalence of hVISA was higher among isolates with a vancomycin minimum inhibitory concentration of 2 mg/L (P = .026). hVISA-infected patients were more likely to have persistent bacteremia (68.4% vs. 37.0%; P = .029) and heart failure (47.4% vs. 19.6%; P = .033). Mortality of hVISA- and non-hVISA-infected patients did not differ (42.1% vs. 34.8%, P = .586). hVISA and non-hVISA isolates were genotypically similar.
In these analyses, hVISA occurred in over one-quarter of MRSA IE isolates, was associated with certain IE complications, and varied in frequency by geographic region.
PMCID: PMC3600359  PMID: 19811099
hVISA; Methicillin-resistant Staphylococcus aureus; endocarditis; genotype
13.  Differentiation of Streptococcus pneumoniae from Nonpneumococcal Streptococci of the Streptococcus mitis Group by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry 
Journal of Clinical Microbiology  2012;50(9):2863-2867.
The differentiation of species within the Streptococcus mitis group has posed a problem in the routine diagnostic microbiology laboratory for some time. It also constitutes a major weakness of recently introduced matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) fingerprinting systems. As the phylogenetic resolution of the spectral similarity measures employed by these systems is insufficient to reliably distinguish between the most closely related members of the group, the major pathogen Streptococcus pneumoniae is frequently misidentified. In this study, a comparative analysis of MALDI-TOF spectra of several species from the S. mitis group has been performed in order to identify single peaks that could be used to improve mass spectrometry-based identification of the respective species. A characteristic peak profile could be identified that unambiguously distinguished the 14 S. pneumoniae isolates studied from 33 nonpneumococcal isolates of the S. mitis group. In addition, specific peak combinations could be assigned to other members of the group. The findings of this study suggest that it is possible to distinguish different species of the S. mitis group by close analysis of their mass peak profiles.
PMCID: PMC3421814  PMID: 22718935
14.  Bloodstream Infection among Children Presenting to a General Hospital Outpatient Clinic in Urban Nepal 
PLoS ONE  2012;7(10):e47531.
There are limited data on the etiology and characteristics of bloodstream infections in children presenting in hospital outpatient settings in South Asia. Previous studies in Nepal have highlighted the importance of murine typhus as a cause of febrile illness in adults and enteric fever as a leading bacterial cause of fever among children admitted to hospital.
We prospectively studied a total of 1084 febrile children aged between 2 months and 14 years presenting to a general hospital outpatient department in Kathmandu Valley, Nepal, over two study periods (summer and winter). Blood from all patients was tested by conventional culture and by real-time PCR for Rickettsia typhi.
Putative etiological agents for fever were identified in 164 (15%) patients. Salmonella enterica serovar Typhi (S. Typhi) was identified in 107 (10%), S. enterica serovar Paratyphi A (S. Paratyphi) in 30 (3%), Streptococcus pneumoniae in 6 (0.6%), S. enterica serovar Typhimurium in 2 (0.2%), Haemophilus influenzae type b in 1 (0.1%), and Escherichia coli in 1 (0.1%) patient. S. Typhi was the most common organism isolated from blood during both summer and winter. Twenty-two (2%) patients were PCR positive for R. typhi. No significant demographic, clinical and laboratory features distinguished culture positive enteric fever and murine typhus.
Salmonella infections are the leading cause of bloodstream infection among pediatric outpatients with fever in Kathmandu Valley. Extension of immunization programs against invasive bacterial disease to include the agents of enteric fever and pneumococcus could improve the health of children in Nepal.
PMCID: PMC3480362  PMID: 23115652
15.  Methicillin-Susceptible Staphylococcus aureus Endocarditis Isolates Are Associated With Clonal Complex 30 Genotype and a Distinct Repertoire of Enterotoxins and Adhesins 
The Journal of Infectious Diseases  2011;204(5):704-713.
Background. Using multinational collections of methicillin-susceptible Staphylococcus aureus (MSSA) isolates from infective endocarditis (IE) and soft tissue infections (STIs), we sought to (1) validate the finding that S. aureus in clonal complex (CC) 30 is associated with hematogenous complications and (2) test the hypothesis that specific genetic characteristics in S. aureus are associated with infection severity.
Methods. IE and STI isolates from 2 cohorts were frequency matched by geographic origin. Isolates underwent spa typing to infer CC and multiplex polymerase chain reaction for presence of virulence genes.
Results. 114 isolate pairs were genotyped. IE isolates were more likely to be CC30 (19.5% vs 6.2%; P = .005) and to contain 3 adhesins (clfB, cna, map/eap; P < .0001 for all) and 5 enterotoxins (tst, sea, sed, see, and sei; P ≤ .005 for all). CC30 isolates were more likely to contain cna, tst, sea, see, seg, and chp (P < .05 for all).
Conclusions. MSSA IE isolates were significantly more likely to be CC30 and to possess a distinct repertoire of virulence genes than MSSA STI isolates from the same region. The genetic basis of this association requires further study.
PMCID: PMC3156104  PMID: 21844296
16.  Murine Typhus and Febrile Illness, Nepal 
Emerging Infectious Diseases  2008;14(10):1656-1659.
Murine typhus was diagnosed by PCR in 50 (7%) of 756 adults with febrile illness seeking treatment at Patan Hospital in Kathmandu, Nepal. Of patients with murine typhus, 64% were women, 86% were residents of Kathmandu, and 90% were unwell during the winter. No characteristics clearly distinguished typhus patients from those with blood culture–positive enteric fever.
PMCID: PMC2609894  PMID: 18826840
Murine typhus; Rickettsia typhi; PCR; Nepal; typhoid; dispatch
18.  The Pneumonia Etiology Research for Child Health Project: A 21st Century Childhood Pneumonia Etiology Study 
The Pneumonia Etiology Research for Child Health (PERCH) project is a 7-country, standardized, comprehensive evaluation of the etiologic agents causing severe pneumonia in children from developing countries. During previous etiology studies, between one-quarter and one-third of patients failed to yield an obvious etiology; PERCH will employ and evaluate previously unavailable innovative, more sensitive diagnostic techniques. Innovative and rigorous epidemiologic and analytic methods will be used to establish the causal association between presence of potential pathogens and pneumonia. By strategic selection of study sites that are broadly representative of regions with the greatest burden of childhood pneumonia, PERCH aims to provide data that reflect the epidemiologic situation in developing countries in 2015, using pneumococcal and Haemophilus influenzae type b vaccines. PERCH will also address differences in host, environmental, and/or geographic factors that might determine pneumonia etiology and, by preserving specimens, will generate a resource for future research and pathogen discovery.
PMCID: PMC3297546  PMID: 22403238
19.  The Definition of Pneumonia, the Assessment of Severity, and Clinical Standardization in the Pneumonia Etiology Research for Child Health Study 
To develop a case definition for the Pneumonia Etiology Research for Child Health (PERCH) project, we sought a widely acceptable classification that was linked to existing pneumonia research and focused on very severe cases. We began with the World Health Organization’s classification of severe/very severe pneumonia and refined it through literature reviews and a 2-stage process of expert consultation. PERCH will study hospitalized children, aged 1–59 months, with pneumonia who present with cough or difficulty breathing and have either severe pneumonia (lower chest wall indrawing) or very severe pneumonia (central cyanosis, difficulty breastfeeding/drinking, vomiting everything, convulsions, lethargy, unconsciousness, or head nodding). It will exclude patients with recent hospitalization and children with wheeze whose indrawing resolves after bronchodilator therapy. The PERCH investigators agreed upon standard interpretations of the symptoms and signs. These will be maintained by a clinical standardization monitor who conducts repeated instruction at each site and by recurrent local training and testing.
PMCID: PMC3297550  PMID: 22403224
20.  Specimen Collection for the Diagnosis of Pediatric Pneumonia 
Diagnosing the etiologic agent of pneumonia has an essential role in ensuring the most appropriate and effective therapy for individual patients and is critical to guiding the development of treatment and prevention strategies. However, establishing the etiology of pneumonia remains challenging because of the relative inaccessibility of the infected tissue and the difficulty in obtaining samples without contamination by upper respiratory tract secretions. Here, we review the published and unpublished literature on various specimens available for the diagnosis of pediatric pneumonia. We discuss the advantages and limitations of each specimen, and discuss the rationale for the specimens to be collected for the Pneumonia Etiology Research for Child Health study.
PMCID: PMC3693496  PMID: 22403227
22.  Cross-Resistance to Lincosamides, Streptogramins A, and Pleuromutilins Due to the lsa(C) Gene in Streptococcus agalactiae UCN70▿  
Streptococcus agalactiae UCN70, isolated from a vaginal swab obtained in New Zealand, is resistant to lincosamides and streptogramins A (LSA phenotype) and also to tiamulin (a pleuromutilin). By whole-genome sequencing, we identified a 5,224-bp chromosomal extra-element that comprised a 1,479-bp open reading frame coding for an ABC protein (492 amino acids) 45% identical to Lsa(A), a protein related to intrinsic LSA resistance in Enterococcus faecalis. Expression of this novel gene, named lsa(C), in S. agalactiae BM132 after cloning led to an increase in MICs of lincomycin (0.06 to 4 μg/ml), clindamycin (0.03 to 2 μg/ml), dalfopristin (2 to >32 μg/ml), and tiamulin (0.12 to 32 μg/ml), whereas no change in MICs of erythromycin (0.06 μg/ml), azithromycin (0.03 μg/ml), spiramycin (0.25 μg/ml), telithromycin (0.03 μg/ml), and quinupristin (8 μg/ml) was observed. The phenotype was renamed the LSAP phenotype on the basis of cross-resistance to lincosamides, streptogramins A, and pleuromutilins. This gene was also identified in similar genetic environments in 17 other S. agalactiae clinical isolates from New Zealand exhibiting the same LSAP phenotype, whereas it was absent in susceptible S. agalactiae strains. Interestingly, this extra-element was bracketed by a 7-bp duplication of a target site (ATTAGAA), suggesting that this structure was likely a mobile genetic element. In conclusion, we identified a novel gene, lsa(C), responsible for the acquired LSAP resistance phenotype in S. agalactiae. Dissection of the biochemical basis of resistance, as well as demonstration of in vitro mobilization of lsa(C), remains to be performed.
PMCID: PMC3067124  PMID: 21245447
23.  Corynebacterium accolens-Associated Pelvic Osteomyelitis▿  
Journal of Clinical Microbiology  2009;48(2):654-655.
Corynebacterium accolens is a rare human pathogen. We encountered a case of C. accolens isolated from a thigh collection in a man with osteomyelitis of the adjacent pubic symphysis.
PMCID: PMC2815633  PMID: 20032254
24.  High-throughput bacterial SNP typing identifies distinct clusters of Salmonella Typhi causing typhoid in Nepalese children 
BMC Infectious Diseases  2010;10:144.
Salmonella Typhi (S. Typhi) causes typhoid fever, which remains an important public health issue in many developing countries. Kathmandu, the capital of Nepal, is an area of high incidence and the pediatric population appears to be at high risk of exposure and infection.
We recently defined the population structure of S. Typhi, using new sequencing technologies to identify nearly 2,000 single nucleotide polymorphisms (SNPs) that can be used as unequivocal phylogenetic markers. Here we have used the GoldenGate (Illumina) platform to simultaneously type 1,500 of these SNPs in 62 S. Typhi isolates causing severe typhoid in children admitted to Patan Hospital in Kathmandu.
Eight distinct S. Typhi haplotypes were identified during the 20-month study period, with 68% of isolates belonging to a subclone of the previously defined H58 S. Typhi. This subclone was closely associated with resistance to nalidixic acid, with all isolates from this group demonstrating a resistant phenotype and harbouring the same resistance-associated SNP in GyrA (Phe83). A secondary clone, comprising 19% of isolates, was observed only during the second half of the study.
Our data demonstrate the utility of SNP typing for monitoring bacterial populations over a defined period in a single endemic setting. We provide evidence for genotype introduction and define a nalidixic acid resistant subclone of S. Typhi, which appears to be the dominant cause of severe pediatric typhoid in Kathmandu during the study period.
PMCID: PMC2897797  PMID: 20509974

Results 1-25 (50)