Infective endocarditis in northeastern Thailand

Infective Endocarditis Caused by Streptococcus Sinensis in a Patient with Bioprosthetic Aortic Valve: A Case Report and Literature Review

Background

Infective endocarditis caused by Streptococcus sinensis is exceedingly rare, with only limited cases reported. Here, we present the first documented case of prosthetic valve endocarditis attributed to Streptococcus sinensis.

Case Presentation

A 40-year-old Chinese female was admitted with a 45-day history of intermittent fever. The presumed diagnosis was a pulmonary infection and antibiotic therapies failed to alleviate her symptoms. On admission, infective endocarditis was suspected, considering the history of aortic valve replacement and recent dental procedure without prophylactic antibiotics. Transesophageal echocardiography disclosed a 3-millimeter vegetation in the prosthetic aortic valve, and metagenomic next-generation sequencing and mass spectrometry identified Streptococcus sinensis. The patient was diagnosed with infective endocarditis. Antibiotic treatments resulted in temporary clinical improvements, although fluctuations in temperature and inflammatory markers led to multiple attempts at antibiotic therapies. At last, the patient underwent an elective aortic valve replacement with a favorable prognosis.

Conclusion

In this case, we demonstrated prosthetic valve endocarditis caused by Streptococcus sinensis, which is an extremely rare pathogen. All reported endocarditis cases caused by Streptococcus sinensis were reviewed and summarized. Most of these patients had rheumatic heart diseases or congenital heart diseases. Antibiotic prophylaxis is important for high-risk procedures. Timely identification of the bacterium is crucial for diagnosis and treatment. Overall, infective endocarditis caused by this bacterium had a good prognosis.

Uncommon pathogens causing infective endocarditis

Infective endocarditis is caused by a wide range of aetiological agents. The microbiology, epidemiology, and treatment of this disease have changed considerably in the last two decades. Staphylococci and streptococci are known to be the classical causative agents; however, blood culture-negative endocarditis caused by fastidious and slow-growing organisms is now common. The list of uncommon pathogens causing endocarditis has expanded in recent years. This is a narrative literature review of the aetiological agents of endocarditis that are rarely encountered in clinical practice, their epidemiology, the characteristics of these pathogens, the clinical presentations of the cases, and their management.

Clinical Significance of a 16S-rDNA Analysis of Heart Valves in Patients with Infective Endocarditis: a Retrospective Study

A substantial proportion of patients with infective endocarditis (IE) are subjected to heart valve surgery. Microbiological findings on valves are important both for diagnostics and for tailored antibiotic therapy, post-operatively. The aims of this study were to describe microbiological findings on surgically removed valves and to examine the diagnostic benefits of 16S-rDNA PCR and sequencing (16S-analysis). Adult patients who were subjected to heart valve surgery for IE between 2012 and 2021 at Skåne University Hospital, Lund, where a 16S-analysis had been performed on the valve, constituted the study population. Data were gathered from medical records, and the results from blood cultures, valve cultures, and 16S-analyses of valves were compared. A diagnostic benefit was defined as providing an agent in blood culture negative endocarditis, providing a new agent in episodes with positive blood cultures, or confirming one of the findings in episodes with a discrepancy between blood and valve cultures. 279 episodes in 272 patients were included in the final analysis. Blood cultures were positive in 259 episodes (94%), valve cultures in 60 episodes (22%), and 16S-analyses in 227 episodes (81%). Concordance between the blood cultures and the 16S-analysis was found in 214 episodes (77%). The 16S-analyses provided a diagnostic benefit in 25 (9.0%) of the episodes. In blood culture negative endocarditis, the 16S-analyses had a diagnostic benefit in 15 (75%) of the episodes. A 16S-analysis should be routinely performed on surgically removed valves in blood culture negative endocarditis. In patients with positive blood cultures, 16S-analysis may also be considered, as a diagnostic benefit was provided in some patients. IMPORTANCE This work demonstrates that it can be of importance to perform both cultures and analysis using 16S-rDNA PCR and sequencing of valves excised from patients undergoing surgery for infective endocarditis. 16S-analysis may help both to establish a microbiological etiology in cases of blood culture negative endocarditis and to provide help in situations where there are discrepancies between valve and blood cultures. In addition, our results show a high degree of concordance between blood cultures and 16S-analyses, indicating that the latter has a high sensitivity and specificity for the etiological diagnosis of endocarditis in patients who were subjected to heart valve surgery.

Case report: Infective endocarditis caused by Streptococcus sinensis: The first case in mainland China and literature review

Streptococcus sinensis was originally described as a causative agent for infective endocarditis in three Chinese patients from Hong Kong in 2002. Subsequently, several cases were reported outside Hong Kong, indicating that it is an emerging pathogen worldwide. We isolated a closely related strain in a young patient diagnosed with infective endocarditis in mainland China. In this paper, we reviewed the course of infection and provided a comprehensive comparison of its clinical characteristics with the reported cases.

Molecular Detection of Bartonella spp. and Hematological Evaluation in Domestic Cats and Dogs from Bangkok, Thailand

(1) Background: Bartonella spp. are Gram-negative, facultative, intracellular bacteria transmitted by hematophagous insects. Several species cause zoonotic diseases such as cat-scratch disease. Bartonella henselae and Bartonella clarridgeiae are the main species found in Thailand, however, there have been few studies on Bartonella spp. In addition, the hematological evaluation of Bartonella-infected animals is limited in Thailand. The aims of this study were prevalence investigation and hematological evaluation of Bartonella-infected dogs and cats residing in Bangkok, Thailand. (2) Methods: In total, 295 dogs and 513 cats were molecularly evaluated to detect Bartonella spp. using PCR with primers targeting the partial gltA, rpoB, ftsZ, ribC, and groEL genes. In total, 651 domestic animals were evaluated for hematological parameters compared between Bartonella-positive and Bartonella-negative animals. (3) Results: Overall, the prevalence of Bartonella spp. was 1.61% which was found only in free-ranging cats (2.83%). Bartonella henselae and B. clarridgeiae were confirmed from a concatenated phylogenetic tree of partial gltA and ribC genes, with 100% bootstrapping replication. For other housekeeping gene sequences, mixed infection was expected from the amplicons of rpoB, ftsZ, and groEL. Importantly, the mean corpuscular volume (MCV) was significantly increased in Bartonella-positive cats. (4) Conclusions: We suggest that B. henselae and B. clarridgeiae are important species and are still circulating in domestic animals, especially cats. The evaluation of blood parameters, especially a raised MCV, should be of concern in Bartonella infection in asymptomatic cats. Additionally, the knowledge of how to prevent Bartonella-related diseases should be promoted with people in at-risk situations.

Partial DnaK protein expression from Coxiella-like endosymbiont of Rhipicephalus annulatus tick

Q fever is one of the most important zoonotic diseases caused by the obligate intracellular bacteria, Coxiella burnetii. This bacterial infection has been frequently reported in both humans and animals, especially ruminants. Ticks are important ectoparasite and serve as reservoir hosts of Coxiella-like endosymbionts (CLEs). In this study, we have attempted to express chaperone-coding genes from CLEs of Rhipicephalus annulatus ticks collected fromcow path. The partial DnaK coding sequence has been amplified and expressed by Escherichia coli. Amino acid sequences have been analyzed by MS-MS spectrometry and the UniProt database. Despites nucleotide sequences indicating high nucleotide variation and diversity, many nucleotide substitutions are synonymous. In addition, amino acid substitutions compensate for the physicochemical properties of the original amino acids. Immune Epitope Database and Analysis Resource (IEDB-AR) was employed to indicate the antigenicity of the partial DnaK protein and predict the epitopes of B-and T-cells. Interestingly, some predicted HLA-A and B alleles of the MHC-I and HLA-DR alleles belonging to MHC-II were similar to T-cell responses to C. burnetii in Q fever patients. Therefore, the partial DnaK protein of CLE from R. annulatus could be considered a vaccine candidate and immunogenic marker with future prospects.

Canine and feline vector-borne diseases of zoonotic concern in Southeast Asia

Dogs and cats are important hosts and reservoirs of many viral, bacterial, protozoal, and helminthic pathogens transmitted by arthropods, including some of zoonotic concern. By sharing the same environment, these companion animals play an important role in the transmission of zoonotic pathogens to humans in various regions and socioeconomic contexts. While canine and feline vector-borne diseases (VBD) are of major concern in wealthy regions (e.g. Europe and North America), less attention has been received in developing countries such as those in Southeast Asia (SEA). This review provides summarized and updated information on canine and feline VBD with emphasis on those of zoonotic concern in SEA. Of these, zoonotic bacteria (i.e. Bartonella henselae, Bartonella clarridgeiae, and Rickettsia felis) and filarial nematodes (i.e. Brugia malayi, Dirofilaria repens, and Dirofilaria immitis) stand out as the most important in veterinary and human medicine. Additionally, the recent finding of Leishmania infantum in dogs in SEA raised more concerns about the spreading of this zoonotic agent in this region. Further epidemiological surveys, especially in countries with extremely scant information such as Cambodia, Laos, Myanmar, and Timor-Leste are advocated. Additionally, effective control measures of canine and feline VBD as well as their arthropod vectors should be simultaneously performed for the management of zoonotic infections.

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Many canine and feline vector-borne infections affect animals and humans in Southeast Asia.

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Ticks, fleas and mosquitoes are the most common vectors transmitting pathogens to dogs, cats and humans in Southeast Asia.

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Bartonella henselae, Rickettsia felis and Dirofilaria repens are of concern to human health in this region.

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Collaboration between governments and researchers is encouraged for a better management of vector-borne diseases.

Infective endocarditis profile, prognostic factors and in-hospital mortality: 6-year trends from a tertiary university center in South America

BACKGROUND

Infective endocarditis (IE) remains an expressive health problem with high morbimortality rates. Despite its importance, epidemiological and microbiological data remain scarce, especially in developing countries.

AIM

This study aims to describe IE epidemiological, clinical, and microbiological profile in a tertiary university center in South America, and to identify in-hospital mortality rate and predictors.

METHODS

An observational, retrospective study of 167 patients, who fulfilled modified Duke's criteria during a six-year enrollment period, from January 2010 to December 2015. The primary outcome was defined as in-hospital mortality analyzed according to treatment received (clinical vs surgical). Multivariate analysis identified mortality predictors.

RESULTS

The median age was 60 years (Q₁ -Q₃ 50-71), and 66% were male. Echocardiogram demonstrated vegetations in 90.4%. An infective agent was identified in 76.6%, being Staphylococcus aureus (19%), Enterococcus (12%), coagulase-negative staphylococci (10%), and Streptococcus viridans (9.6%) the most prevalent. Overall in-hospital mortality was 41.9%, varying from 49.4% to 34.1%, in clinical and surgical patients, respectively (P = .047). On multivariate analysis, diabetes mellitus (odds ratio [OR], 2.5), previous structural heart disease (OR, 3.1), and mitral valve infection (OR, 2.1) were all-cause death predictors. Surgical treatment was the only variable related to a better outcomes (OR, 0.45; 95% Confidence Interval, 0.2-0.9).

CONCLUSION

This study presents IE profile and all-cause mortality in a large patient's cohort, comprising a 6-years' time window, a rare initiative in developing countries. Elderly and male patients predominated, while S. aureus was the main microbiological agent. Patients conservatively treated presented higher mortality than surgically managed ones. Epidemiological studies from developing countries are essential to increase IE understanding.

Factors Affecting Mortality in Patients with Blood-Culture Negative Infective Endocarditis

Infective endocarditis retains high morbidity and mortality rates despite recent advances in diagnostics, pharmacotherapy, and surgical intervention. Risk stratification in endocarditis patients, including blood-culture negative endocarditis, is crucial in deciding the optimal management strategy; however, the studies investigating risk stratification in these patients were lacking despite the difference with blood-culture positive endocarditis. The aim of this study is to identify risk factors associated with in-hospital mortality in blood-culture negative infective endocarditis patients. A retrospective cohort study was conducted at National Cardiovascular Center Harapan Kita, Jakarta in blood-culture negative infective endocarditis patients from 2013 to 2015. Patient characteristics, clinical parameters, echocardiographic parameters, and clinical complications were collected from medical records and hospital information systems. There were 146 patients that satisfy the inclusion and exclusion criteria out of 162 patients with blood-culture infective endocarditis. The in-hospital mortality rate was 13.5%. On bivariate analyses, factors that were related to in-hospital mortality include New York Heart Association (NYHA) class III and IV heart failure ( p  = 0.007), history of hypertension ( p  = 0.021), stroke during hospitalization ( p  < 0.001), the decline in renal function ( p  < 0.001), and surgery ( p  = 0.028). Variables that were independently associated with mortality upon multivariate analysis were heart failure NYHA functional class III and IV (OR 7.56, p  = 0.011), worsening kidney function (OR 10.23, p  < 0.001), and stroke during hospitalization (OR 8.92, p  = 0.001). Presence of heart failure with NYHA functional class III and IV, worsening kidney function, and stroke during hospitalization were independently associated with in-hospital mortality in blood-culture infective endocarditis patients.

Cumulative incidence and mortality of infective endocarditis in Siriraj hospital-Thailand: a 10-year retrospective study

Background

To investigate the cumulative incidence of and factors associated with mortality among patients with infective endocarditis (IE) at Thailand’s largest national tertiary referral center.

Methods

Medical charts of adult patients diagnosed with IE by Duke criteria at Siriraj Hospital during January 2005 to May 2015 were retrospectively reviewed.

Results

Of 380 patients, 66.3% had definite IE, and 81.3% had native valve IE (NVE). Cumulative IE incidence was 5.67/1000 admissions. The most common pathogens were viridans group streptococci (VGS) (39.7%), methicillin-sensitive Staphylococcus aureus (MSSA) (13.1%), and beta-hemolytic streptococci (11.5%) in NVE; and, MSSA (20.3%), VGS (20.3%), and Enterococcus spp. (16.9%) in prosthetic valve (PVE) or device-related IE (DRIE). Overall in-hospital mortality was 18.4%. Mortality was significantly higher in PVE/DRIE than in NVE (26.8% vs. 16.5%, p = 0.047). End-stage renal disease (ESRD) (aOR: 9.43, 95% CI: 2.36–37.70), diabetes mellitus (DM) (aOR: 2.81, 95% CI: 1.06–7.49), neurological complication (aOR: 14.16, 95% CI: 5.11–39.22), congestive heart failure (aOR: 4.32, 95% CI: 1.91–9.75), hospital-acquired infection (aOR: 3.78, 95% CI: 1.66–8.57), renal complication (aOR: 3.12, 95%CI: 1.32–7.37), and other complication during admission (aOR: 3.28, 95% CI: 1.41–7.61) were independently associated with mortality.

Conclusions

The incidence of IE, and the mortality rate among those diagnosed with IE are both increasing in Thailand – particularly among those with PVE or DRIE. End-stage renal disease, diabetes mellitus, and development of IE-related complications during admission were found to be independent predictors of mortality.

Evolving trends in infective endocarditis in a developing country: a consequence of medical progress?

BACKGROUND

Staphylococcus has replaced streptococcus as the most common cause of infective endocarditis (IE) in developed health care systems. The trend in developing countries is less clear.

AIM

To examine the epidemiological trends of infective endocarditis in a developing nation.

METHODS

Single-centre, retrospective study of patients admitted with IE to a tertiary hospital in Malaysia over a 12-year period.

RESULTS

The analysis included 182 patients (n = 153 Duke's definite IE, n = 29 possible IE). The mean age was 51 years. Rheumatic heart disease was present in 42%, while 7.6% were immunocompromised. IE affected native valves in 171 (94%) cases. Health-care associated IE (HCAIE) was recorded in 68 (37.4%). IE admission rates increased from 25/100,000 admissions (2012) to 59/100,000 admissions (2017). At least one major complication on admission was detected in 59 (32.4%) patients. Left-sided IE was more common than right-sided IE [n = 159 (87.4%) vs. n = 18 (9.9%)]. Pathogens identified by blood culture were staphylococcus group [n = 58 (40.8%)], streptococcus group [n = 51 (35.9%)] and Enterococcus species [n = 13 (9.2%)]. staphylococcus infection was highest in the HCAIE group. In-hospital death occurred in 65 (35.7%) patients. In-hospital surgery was performed for 36 (19.8%) patients. At least one complication was documented in 163 (85.7%).

CONCLUSION

Staphylococcus is the new etiologic champion, reflecting the transition of the healthcare system. Streptococcus is still an important culprit organism. The incidence rate of IE appears to be increasing. The rate of patients with underlying rheumatic heart disease is still high.

Changing landscapes of Southeast Asia and rodent-borne diseases: decreased diversity but increased transmission risks

The reduction in biodiversity from land use change due to urbanization and agricultural intensification appears to be linked to major epidemiological changes in many human diseases. Increasing disease risks and the emergence of novel pathogens result from increased contact among wildlife, domesticated animals, and humans. We investigated the relationship between human alteration of the environment and the occurrence of generalist and synanthropic rodent species in relation to the diversity and prevalence of rodent-borne pathogens in Southeast Asia, a hotspot of threatened and endangered species, and a foci of emerging infectious diseases. We used data from an extensive pathogen survey of rodents from seven sites in mainland Southeast Asia in conjunction with past and present land cover analyses. At low spatial resolutions, we found that rodent-borne pathogen richness is negatively associated with increasing urbanization, characterized by increased habitat fragmentation, agriculture cover and deforestation. However, at a finer spatial resolution, we found that some major pathogens are favored by environmental characteristics associated with human alteration including irrigation, habitat fragmentation, and increased agricultural land cover. In addition, synanthropic rodents, many of which are important pathogen reservoirs, were associated with fragmented and human-dominated landscapes, which may ultimately enhance the opportunities for zoonotic transmission and human infection by some pathogens.

The Prevalence of Bartonella Bacteria in Cattle Lice Collected from Three Provinces of Thailand

Cattle lice are obligatory blood-sucking parasites, which is the cause of animal health problems worldwide. Recently, several studies have revealed that pathogenic bacteria could be found in cattle lice, and it can act as a potential vector for transmitting louse-borne diseases. However, the cattle lice and their pathogenic bacteria in Thailand have never been evaluated. In the present study, we aim to determine the presence of bacterial pathogens in cattle lice collected from three localities of Thailand. Total genomic DNA was extracted from 109 cattle louse samples and the Polymerase Chain Reaction (PCR) of 18S rRNA was developed to identify the cattle louse. Moreover, PCR was used for screening Bartonella spp., Acinetobacter spp., and Rickettsia spp. in cattle louse samples. The positive PCR products were cloned and sequenced. The phylogenetic tree based on the partial 18S rRNA sequences demonstrated that cattle lice species in this study are classified into two groups according to reference sequences; Haematopinus quadripertusus and Haematopinus spp. closely related to H. tuberculatus. The pathogen detection revealed that Bartonella spp. DNA of gltA and rpoB were detected in 25 of 109 samples (22.93%) both egg and adult stages, whereas Acinetobacter spp. and Rickettsia spp. were not detected in all cattle lice DNA samples. The gltA and rpoB sequences showed that the Bartonella spp. DNA was found in both H. quadripertusus and Haematopinus spp. closely related to H. tuberculatus. This study is the first report of the Bartonella spp. detected in cattle lice from Thailand. The finding obtained from this study could be used to determine whether the cattle lice can serve as a potential vector to transmit these pathogenic bacteria among cattle and may affect animal to human health.

Lesson of the month 2: When steroids stop working - infective endocarditis, the great mimicker

A 63-year-old man with an extensive travel history to South East Asia presented with generalised malaise, temporal headaches and high inflammatory markers. He was treated with corticosteroids for presumed giant cell arteritis. Unsuccessful attempts to wean him from prednisolone prompted further investigations by rheumatology, haematology and finally ophthalmology. Roth spots were identified which prompted blood cultures to be taken. All three sets grew Streptococcus sinensis, an alpha-haemolytic Streptococcus reported as an emerging cause of endocarditis worldwide. The patient had signs of severe aortic regurgitation, confirmed on transthoracic echo. A transoesophageal echo demonstrated large aortic valve vegetations. He underwent an aortic valve replacement and completed 6 weeks of intravenous antibiotics with resolution of his symptoms.This case illustrates the importance of challenging a previous diagnosis, including repeat examination, when a patient's condition does not evolve as expected. Endocarditis is recognised as a great imitator and the diagnosis remains challenging.

Bartonella henselae infective endocarditis with dissemination: A case report and literature review in Southeast Asia

Bartonella is among the most common causes of culture-negative infective endocarditis, with B. henselae being one of the most frequently reported species. The clinical presentation of Bartonella endocarditis is similar to that of subacute bacterial endocarditis caused by other bacteria and the diagnosis can be challenging since the organism is difficult to isolate using standard microbiologic culture techniques. In clinical practice, Bartonella endocarditis is usually diagnosed based on serology. To date, only a handful of cases of infective endocarditis caused by Bartonella have been reported in Thailand. Here, we report the case of 51-year-old Thai male with B. henselae endocarditis with dissemination to the lungs, bones, subcutaneous tissue, epididymis, and lymph nodes with a successful outcome.

Baseline C-reactive protein levels and prognosis in patients with infective endocarditis: A prospective cohort study

Background

Early diagnosis and risk-stratification among infective endocarditis (IE) patients are limited by poor microbiological yield and inadequate characterization of vegetations. A simple tool that can predict adverse outcomes in the early phase of management is required.

Aim

To study the prognostic value of C-reactive protein (CRP) levels at admission and its role in predicting various clinical outcomes.

Methods

In a prospective study of consecutive IE patients diagnosed by modified Duke’s criteria, we measured the peak levels of CRP and erythrocyte sedimentation rate (ESR) in the first 3 days of admission and correlated it with in-hospital mortality, six-month mortality, embolic phenomena and the need for urgent surgery. Predefined laboratory-microbiological sampling protocols and antibiotic-initiation protocols were followed. Receiver-operating-characteristics curves were generated to identify a reliable cut-off for CRP in predicting various outcomes.

Results

Out of 101 patients who were treated, 85 patients had ‘definite’ IE. Blood cultures were positive in 55% (n = 39); and Staphylococcus species was the most common organism. Major complications occurred in 74.1% (n = 63) and in-hospital mortality was 32.9% (n = 28). Mean ESR and CRP levels were 102 ± 31 mm/h and 51 ± 20 mg/l, respectively. In multivariable analysis, high CRP levels were independently predictive of mortality, major complications, embolic events and need for urgent surgery. A CRP >40 mg/l predicted adverse outcomes with a sensitivity of 73% and specificity of 99%.

Conclusion

The study shows that baseline CRP level in the first 3 days of admission is a strong predictor of short term adverse outcomes in IE patients, and a useful marker for early risk stratification.

Febrile illness in Asia: gaps in epidemiology, diagnosis and management for informing health policy

BACKGROUND

Increasing evidence is becoming available on the aetiology and management of fevers in Asia; the importance of these fevers has increased with the decline in the incidence of malaria.

AIMS

To conduct a narrative review of the epidemiology and management of fevers in South and South-East Asia and to highlight gaps in our knowledge that impair evidence-based health policy decisions.

SOURCES

A narrative review of papers published since 2012 on developments in fever epidemiology, diagnosis and treatment in South and South-East Asia. The papers that the authors felt were pivotal, from their personal perspectives, are discussed.

CONTENT

We identified 100 studies. Among the 30 studies (30%)-including both children and adults-that investigated three or more pathogens, the most frequently reported fever aetiology was dengue (reported by 15, 50%), followed by leptospirosis (eight, 27%), scrub typhus (seven, 23%) and Salmonella serovar Typhi (six, 20%). Among four studies investigating three or more pathogens in children, dengue and Staphylococcus aureus were the most frequent, followed by non-typhoidal Salmonella spp, Streptococcus pneumoniae, Salmonella serovar Typhi, and Orientia tsutsugamushi. Increased awareness is needed that rickettsial pathogens are common but do not respond to cephalosporins, and that alternative therapies, such as tetracyclines, are required.

IMPLICATIONS

Many key gaps remain, and consensus guidelines for study design are needed to aid comparative understanding of the epidemiology of fevers. More investment in developing accurate and affordable diagnostic tests for rural Asia and independent evaluation of those already on the market are needed. Treatment algorithms, including simple biomarker assays, appropriate for empirical therapy of fevers in different areas of rural Asia should be a major aim of fever research. Enhanced antimicrobial resistance (AMR) surveillance and openly accessible databases of geography-specific AMR data would inform policy on empirical and specific therapy. More investment in innovative strategies facilitating infectious disease surveillance in remote rural communities would be an important component of poverty reduction and improving public health.

Acute Q Fever Case Detection among Acute Febrile Illness Patients, Thailand, 2002-2005

Acute Q fever cases were identified from a hospital-based acute febrile illness study conducted in six community hospitals in rural north and northeast Thailand from 2002 to 2005. Of 1,784 participants that underwent Coxiella burnetii testing, nine (0.5%) participants were identified in this case-series as acute Q fever cases. Eight case-patients were located in one province. Four case-patients were hospitalized. Median age was 13 years (range: 7-69); five were male. The proportion of children with acute Q fever infection was similar to adults (P = 0.17). This previously unrecognized at-risk group, school-age children, indicates that future studies and prevention interventions should target this population. The heterogeneity of disease burden across Thailand and milder clinical presentations found in this case-series should be considered in future studies. As diagnosis based on serology is limited during the acute phase of the disease, other diagnostic options, such as polymerase chain reaction, should be explored to improve acute case detection.

Underrecognized arthropod-borne and zoonotic pathogens in northern and northwestern Thailand: serological evidence and opportunities for awareness

Although scrub typhus and murine typhus are well-described tropical rickettsial illnesses, especially in Southeast Asia, only limited evidence is available for rickettsia-like pathogens contributing to the burden of undifferentiated febrile illness. Using commercially available kits, this study measured immunoglobulin G (IgG) antibody seroprevalence for Coxiella burnetii, Ehrlichia chaffeensis, Bartonella henselae, Anaplasma phagocytophilum, and spotted fever group rickettsiae (SFGR) in 375 patients enrolled in undifferentiated febrile illness studies at Chiangrai (northern Thailand) and Mae Sot (Thai–Myanmar border). Ehrlichia and SFGR were the most common causes of IgG seropositivity. A distinct relationship between age and seropositivity was found in Chiangrai with acquisition of IgG titers against Ehrlichia, Bartonella, Anaplasma, and SFGR in young adulthood, suggesting cumulative exposure to these pathogens. At Mae Sot, high early IgG titers against Ehrlichia and SFGR were common, whereas Anaplasma and Bartonella IgG titers increased at 50–60 years. Q fever associated with low IgG positivity at both study sites, with significantly higher prevalence at 30 years of age in Chiangrai. These data suggest that other rickettsial illnesses could contribute to the burden of febrile illness in Thailand and possibly adjacent regions. Improved diagnostics and better understanding of antibody longevity and cross-reactivity will improve identification and management of these easily treatable infectious diseases.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change

Coxiella burnetii is the agent of Q fever, or "query fever," a zoonosis first described in Australia in 1937. Since this first description, knowledge about this pathogen and its associated infections has increased dramatically. We review here all the progress made over the last 20 years on this topic. C. burnetii is classically a strict intracellular, Gram-negative bacterium. However, a major step in the characterization of this pathogen was achieved by the establishment of its axenic culture. C. burnetii infects a wide range of animals, from arthropods to humans. The genetic determinants of virulence are now better known, thanks to the achievement of determining the genome sequences of several strains of this species and comparative genomic analyses. Q fever can be found worldwide, but the epidemiological features of this disease vary according to the geographic area considered, including situations where it is endemic or hyperendemic, and the occurrence of large epidemic outbreaks. In recent years, a major breakthrough in the understanding of the natural history of human infection with C. burnetii was the breaking of the old dichotomy between "acute" and "chronic" Q fever. The clinical presentation of C. burnetii infection depends on both the virulence of the infecting C. burnetii strain and specific risks factors in the infected patient. Moreover, no persistent infection can exist without a focus of infection. This paradigm change should allow better diagnosis and management of primary infection and long-term complications in patients with C. burnetii infection.

A Decennium of Etiology and Antimicrobial Susceptibility Patterns in Patients with Infective Endocarditis at a University Hospital, Thailand

Infective endocarditis is an infection with a high mortality rate. Antimicrobial therapy is important for treatment, but data on antimicrobial susceptibilities are limited. This retrospective study analyzed data on the causative microorganisms and antimicrobial susceptibility patterns in patients with infective endocarditis 18 years of age or older who received inpatient care between 2006 and 2015 at King Chulalongkorn Memorial Hospital. A total of 213 patients fulfilled the inclusion criteria. Streptococcus spp. (54.5%) was the most common organism. Viridans streptococcus (46%) was the leading pathogen, followed by Group B streptococcus (27%). The majority of Streptococcus spp. were susceptible to penicillin (82.7%). Among Streptococcus spp., Streptococcus suis had the highest MIC₉₀ of penicillin and cefotaxime (1.65 and 0.95 μg/ml, respectively). There was a statistically significant increase in the MICs of penicillin and cefotaxime for Streptococcus suis (P = 0.03 and 0.04). Only 45.5% of Streptococcus suis and 77.5% of Viridans streptococcus were susceptible to penicillin. All Enterococcus spp. and Staphylococcus spp. were susceptible to vancomycin. In conclusion, the prevalence of Group B streptococcus isolates increased among patients with infective endocarditis in Thailand. Streptococcus suis had the highest MIC₉₀ and proportion of isolates not susceptible to penicillin. Rigorous restriction of the use of antimicrobial agents in animal feeds should be a primary concern.

Seroprevalence of Q Fever, Brucellosis, and Bluetongue in Selected Provinces in Lao People's Democratic Republic

This study has determined the proportional seropositivity of two zoonotic diseases, Q fever and brucellosis, and bluetongue virus (BTV) which is nonzoonotic, in five provinces of Lao People's Democratic Republic (PDR) (Loungphabang, Luangnumtha, Xayaboury, Xiengkhouang, and Champasak, and Vientiane Province and Vientiane capital). A total of 1,089 samples from buffalo, cattle, pigs, and goats were tested, with seropositivity of BTV (96.7%), Q fever (1.2%), and brucellosis (0.3%). The results of this survey indicated that Q fever seropositivity is not widely distributed in Lao PDR; however, Xayaboury Province had a cluster of seropositive cattle in seven villages in four districts (Botan, Kenthao, Paklaiy, and Phiang) that share a border with Thailand. Further studies are required to determine if Xayaboury Province is indeed an epidemiological hot spot of Q fever activity. There is an urgent need to determine the levels of economic loss and human health-related issues caused by Q fever, brucellosis, and BTV in Lao PDR.

Coexistence of Bartonella henselae and B. clarridgeiae in populations of cats and their fleas in Guatemala

Cats and their fleas collected in Guatemala were investigated for the presence of Bartonella infections. Bartonella bacteria were cultured from 8.2% (13/159) of cats, and all cultures were identified as B. henselae. Molecular analysis allowed detection of Bartonella DNA in 33.8% (48/142) of cats and in 22.4% (34/152) of cat fleas using gltA, nuoG, and 16S-23S internal transcribed spacer targets. Two Bartonella species, B. henselae and B. clarridgeiae, were identified in cats and cat fleas by molecular analysis, with B. henselae being more common than B. clarridgeiae in the cats (68.1%; 32/47 vs 31.9%; 15/47). The nuoG was found to be less sensitive for detecting B. clarridgeiae compared with other molecular targets and could detect only two of the 15 B. clarridgeiae-infected cats. No significant differences were observed for prevalence between male and female cats and between different age groups. No evident association was observed between the presence of Bartonella species in cats and in their fleas.

The Distribution and Diversity of Bartonella Species in Rodents and Their Ectoparasites across Thailand

Our study highlights the surveillance of Bartonella species among rodents and their associated ectoparasites (ticks, fleas, lice, and mites) in several regions across Thailand. A total of 619 rodents and 554 pooled ectoparasites (287 mite pools, 62 flea pools, 35 louse pools, and 170 tick pools) were collected from 8 provinces within 4 regions of Thailand. Bandicota indica (279), Rattus rattus (163), and R. exulans (96) were the most prevalent species of rats collected in this study. Real-time PCR assay targeting Bartonella-specific ssrA gene was used for screening and each positive sample was confirmed by PCR using nuoG gene. The prevalence of Bartonella DNA in rodent (around 17%) was recorded in all regions. The highest prevalence of Bartonella species was found in B. savilei and R. rattus with the rate of 35.7% (5/14) and 32.5% (53/163), respectively. High prevalence of Bartonella-positive rodent was also found in B. indica (15.1%, 42/279), and R. norvegicus (12.5%, 5/40). In contrast, the prevalence of Bartonella species in ectoparasites collected from the rats varied significantly according to types of ectoparasites. A high prevalence of Bartonella DNA was found in louse pools (Polyplax spp. and Hoplopleura spp., 57.1%) and flea pools (Xenopsylla cheopis, 25.8%), while a low prevalence was found in pools of mites (Leptotrombidium spp. and Ascoschoengastia spp., 1.7%) and ticks (Haemaphysalis spp., 3.5%). Prevalence of Bartonella DNA in ectoparasites collected from Bartonella-positive rodents (19.4%) was significantly higher comparing to ectoparasites from Bartonella-negative rodents (8.7%). The phylogenetic analysis of 41 gltA sequences of 16 Bartonella isolates from rodent blood and 25 Bartonella-positive ectoparasites revealed a wide range of diversity among Bartonella species with a majority of sequences (61.0%) belonging to Bartonella elizabethae complex (11 rodents, 1 mite pool, and 5 louse pools), while the remaining sequences were identical to B. phoceensis (17.1%, 1 mite pool, 5 louse pools, and 1 tick pool), B. coopersplainensis (19.5%, 5 rodents, 1 louse pool, and 2 tick pools), and one previously unidentified Bartonella species (2.4%, 1 louse pool).

Bartonella henselae endocarditis in Laos - 'the unsought will go undetected'

Background

Both endocarditis and Bartonella infections are neglected public health problems, especially in rural Asia. Bartonella endocarditis has been described from wealthier countries in Asia, Japan, Korea, Thailand and India but there are no reports from poorer countries, such as the Lao PDR (Laos), probably because people have neglected to look.

Methodology/Principal Findings

We conducted a retrospective (2006–2012), and subsequent prospective study (2012–2013), at Mahosot Hospital, Vientiane, Laos, through liaison between the microbiology laboratory and the wards. Patients aged >1 year admitted with definite or possible endocarditis according to modified Duke criteria were included. In view of the strong suspicion of infective endocarditis, acute and convalescent sera from 30 patients with culture negative endocarditis were tested for antibodies to Brucella melitensis,Mycoplasma pneumoniae,Bartonella quintana,B. henselae,Coxiella burnetii and Legionella pneumophila. Western blot analysis using Bartonella species antigens enabled us to describe the first two Lao patients with known Bartonella henselae endocarditis.

Conclusions/Significance

We argue that it is likely that Bartonella endocarditis is neglected and more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. Considering the high prevalence of rheumatic heart disease in Asia, there is remarkably little evidence on the bacterial etiology of endocarditis. Most evidence is derived from wealthy countries and investigation of the aetiology and optimal management of endocarditis in low income countries has been neglected. Interest in Bartonella as neglected pathogens is emerging, and improved methods for the rapid diagnosis of Bartonella endocarditis are needed, as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis and multicenter trials to optimize treatment are required. More understanding is needed on the risk factors for Bartonella endocarditis and the importance of vectors and vector control.

Infection of heart valves (endocarditis) with bacteria is an important condition, especially afflicting those with rheumatic heart disease, and has a high mortality if untreated. Most of the evidence for optimal antibiotic and surgical management comes from wealthy countries. There are no published data from poorer countries in SE Asia despite a high burden of rheumatic heart disease. We investigated the bacterial infections of heart valves in the Lao PDR (Laos) through heart ultrasound scans and analysis of patients' blood. We provide evidence of infection with the poorly understood bacteria Bartonella henselae (the cause of cat scratch disease) in two patients from Laos. We argue that it is likely that Bartonella endocarditis is more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. This is important as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis. There have been great advances in the wealthy world in the diagnosis and treatment of endocarditis but these have not been assessed or implemented in poorer countries. More evidence on the causes and optimal management of endocarditis in low income countries is needed.

Infective endocarditis in the Lao PDR: clinical characteristics and outcomes in a developing country

INTRODUCTION

Data on infective endocarditis (IE) in Southeast Asia are scarce.

OBJECTIVES

To describe the clinical epidemiology of IE in Lao PDR, a lower middle-income country.

METHODS

A single centre retrospective study at Mahosot Hospital, Vientiane. Patients aged over 1year of age admitted 2006-2012 to Mahosot Hospital with definite or possible IE by modified Duke criteria were included.

RESULTS

Thirty-six patients fulfilled the inclusion criteria; 33 (91.7%) had left-sided IE. Eleven (30.6%) had definite IE and 25 (69.4%) possible left-sided IE. Median age was 25years old [IQR 18-42]. Fifteen patients (41.7%) were males. Underlying heart diseases included: rheumatic valve disease in 12 (33.3%), congenital heart disease in 7 (19.4%), degenerative valve disease in 3 (8.3%), and of unknown origin in 14 (38.9%) patients. Native valve IE was present in 30 patients (83.3%), and prosthetic valve IE in 6 patients (16.7%). The most frequent pathogens were Streptococcus spp. in 7 (19.4%). Blood cultures were negative in 22 patients (61.1%). Complications included: heart failure in 11 (30.6%), severe valve regurgitation in 7 (19.4%); neurological event in 7 (19.4%); septic shock or severe sepsis in 5 (13.9%); and cardiogenic shock in 3 patients (8.3%). No patient underwent heart surgery. Fourteen (38.9%) had died by follow-up after a median of 2.1years [IQR 1-3.2]; and 3 (8.3%) were lost to follow-up.

CONCLUSIONS

Infective endocarditis, a disease especially of young adults and mainly caused by Streptococcus spp., was associated with rheumatic heart disease and had high mortality in Laos.