Temporal trend of drug-resistant tuberculosis among Thai children during 2006-2021

BACKGROUND

The prevalence of drug-resistant tuberculosis (DR-TB) in adults has stabilized in the past decade. Our study aimed to describe the prevalence of DR-TB in Thai children between 2006 and 2021.

MATERIALS AND METHODS

Children younger than 15 years old who had culture-confirmed Mycobacterium tuberculosis complex (MTB), positive PCR-MTB, or positive Xpert MTB/RIF were included in this cohort. Drug susceptibility testing (DST) was performed using phenotypic and/or genotypic methods. The prevalence of DR-TB was compared using the chi-square test.

RESULTS

Among 163 confirmed TB cases (44% as pulmonary TB, 27% as extrapulmonary TB, and 29% with both), the median age (IQR) was 12.2 (7.3-14.2) years. DST was performed in 139 cases (85%), revealing prevalences of all DR-TB, isoniazid-resistant TB (Hr-TB), and rifampicin monoresistant/multidrug-resistant TB (Rr/MDR-TB) of 21.6% (95% CI 14.7-28.4), 10.8% (95% CI 5.6-16.0%), and 2.9% (95% CI 0.1-5.7%), respectively. The DR-TB rates did not differ significantly between 2006-2013, 2014-2018, and 2019-2021 (p > 0.05). Two pre-extensively DR-TB (pre-XDR) cases with fluoroquinolone resistance were detected after 2014.

CONCLUSION

The prevalence of DR-TB in Thai children was stable. However, one-tenth of DR-TB cases confirmed with DST were Hr-TB, which required adjustment of the treatment regimen. The pre-XDR cases should be closely monitored.

Predictors and outcomes of peritoneal dialysis-related infections due to filamentous molds (MycoPDICS)

Introduction

We sought to evaluate the predictors and outcomes of mold peritonitis in patients with peritoneal dialysis (PD).

Methods

This cohort study included PD patients from the MycoPDICS database who had fungal peritonitis between July 2015-June 2020. Patient outcomes were analyzed by Kaplan Meier curves and the Log-rank test. Multivariable Cox proportional hazards model regression was used to estimating associations between fungal types and patients’ outcomes.

Results

The study included 304 fungal peritonitis episodes (yeasts n = 129, hyaline molds n = 122, non-hyaline molds n = 44, and mixed fungi n = 9) in 303 patients. Fungal infections were common during the wet season (p <0.001). Mold peritonitis was significantly more frequent in patients with higher hemoglobin levels, presentations with catheter problems, and positive galactomannan (a fungal cell wall component) tests. Patient survival rates were lowest for non-hyaline mold peritonitis. A higher hazard of death was significantly associated with leaving the catheter in-situ (adjusted hazard ratio [HR] = 6.15, 95%confidence interval [CI]: 2.86–13.23) or delaying catheter removal after the diagnosis of fungal peritonitis (HR = 1.56, 95%CI: 1.00–2.44), as well as not receiving antifungal treatment (HR = 2.23, 95%CI: 1.25–4.01) or receiving it for less than 2 weeks (HR = 2.13, 95%CI: 1.33–3.43). Each additional day of antifungal therapy beyond the minimum 14-day duration was associated with a 2% lower risk of death (HR = 0.98, 95%CI: 0.95–0.999).

Conclusion

Non-hyaline-mold peritonitis had worse survival. Longer duration and higher daily dosage of antifungal treatment were associated with better survival. Deviations from the 2016 ISPD Peritonitis Guideline recommendations concerning treatment duration and catheter removal timing were independently associated with higher mortality.

Genetically Confirmed <b><i>Edwardsiella tarda</i></b> Peritonitis was Associated with Improper Caregiver’s Hand Hygiene during Peritoneal Dialysis Bag Exchange

Edwardsiella tarda is a Gram-negative bacillus and is responsible for waterborne disease. This is the first case report of peritoneal dialysis (PD)-associated peritonitis caused by genetically confirmed E. tarda, which was transmitted from the caregiver's hand during PD bag exchange. Aside from that, the caregiver was a fishmonger and a gastrointestinal carrier of the pathogen. Prior to the onset of peritonitis, the caregiver reported that she did not wash her hands every time when performing the PD bag exchange. Although extraintestinal edwardsiellosis usually poses a poor outcome, PD-associated peritonitis with this species is paradoxical if diagnosed early, and treatment is promptly provided, as presented here. This case emphasizes the importance of hand hygiene in preventing environment-bound infection in patients on PD and demonstrates the unusual route of infection, contamination during PD bag exchange.

Notch 2 receptor expression and reduced cytotoxicity in MAIT cells of active pulmonary TB patients

BACKGROUND

Knowledge of the prevalence of common sensitizing allergens may aid in overall management of allergic disease in a specified area.

OBJECTIVE

The aim of this study was to identify and analyse the prevalence of common inhaled and food sensitizing allergens in Beijing.

METHODS

This was a retrospective study, analysing demographic data and serum sIgE antibody test results from 59057 outpatients who presented to Beijing TongRen Hospital, from January 2013 to December 2019.

RESULTS

28879 patients (48.9%) showed positive sIgE test results; with significantly more males aged under 16 years sensitized to at least one allergen than females, and most patients (53.62%) were sensitized to multiple allergens. The first inhaled sensitizing allergens was Artemisia grass (11910 (41.24%)); and the first food allergens was crab (3547 (12.28%)). For Artemisia sensitized patients, sIgE levels were mostly at level 5. The number of patients with ragweed allergy is increasing year by year. The detection rates for sIgE to Artemisia, common ragweed, and Humulus grass allergens were significantly higher in August and September. R package ggplot2 analysis, demonstrated strong correlations between tree allergens and common ragweed and Humulus grass allergens (phi coefficients = 0.50 and 0.46, respectively; both P < 0.01).

CONCLUSIONS

The prevalence of sensitization to different allergens in Beijing showed Artemisia grass was the most commonly inhaled sensitizing allergen, and the number of patients with ragweed grass allergy was increasing by year.

Association of Local Unit Sampling and Microbiology Laboratory Culture Practices With the Ability to Identify Causative Pathogens in Peritoneal Dialysis-Associated Peritonitis in Thailand

Introduction

This describes variations in facility peritoneal dialysis (PD) effluent (PDE) culture techniques and local microbiology laboratory practices, competencies, and quality assurance associated with peritonitis, with a specific emphasis on factors associated with culture-negative peritonitis (CNP).

Methods

Peritonitis data were prospectively collected from 22 Thai PD centers between May 2016 and October 2017 as part of the Peritoneal Dialysis Outcomes and Practice Patterns Study. The first cloudy PD bags from PD participants with suspected peritonitis were sent to local and central laboratories for comparison of pathogen identification. The associations between these characteristics and CNP were evaluated.

Results

CNP was significantly more frequent in local laboratories (38%) compared with paired PDE samples sent to the central laboratory (12%, P < 0.05). Marked variations were observed in PD center practices, particularly with respect to specimen collection and processing, which often deviated from International Society for Peritoneal Dialysis Guideline recommendations, and laboratory capacities, capabilities, and certification. Lower rates of CNP were associated with PD nurse specimen collection, centrifugation of PDE, immediate transfer of samples to the laboratory, larger hospital size, larger PD unit size, availability of an on-site nephrologist, higher laboratory capacity, and laboratory ability to perform aerobic cultures, undertake standard operating procedures in antimicrobial susceptibilities, and obtain local accreditation.

Conclusion

There were large variations in PD center and laboratory capacities, capabilities, and practices, which in turn were associated with the likelihood of culturing and correctly identifying organisms responsible for causing PD-associated peritonitis. Deviations in practice from International Society for Peritoneal Dialysis guideline recommendations were associated with higher CNP rates.

The culture from peritoneal dialysis catheter enhances yield of microorganism identification in peritoneal dialysis-related peritonitis

An additional yield of culture from the removed peritoneal dialysis (PD) catheter in diagnosis of pathogen causing refractory peritonitis was assessed in 118 eligible patients from 7 PD centers. Peritoneal dialysis fluid (PDF) culture identified organisms in 86 (72.9%) patients, while the catheter culture identified organisms in 55 (46.6%) patients. PD catheter culture could additionally identify organisms in 19 patients whose PDF culture were negative, increasing the positive culture rate to 89%, in other word 16.1% reducing the culture-negative rate. PD catheter culture provided additional yield, especially in fungal and enterococcal infections.

The utility of stool cultures for diagnosing tuberculosis in people living with the human immunodeficiency virus

BACKGROUND

Delayed diagnosis of tuberculosis (TB) increases mortality.

OBJECTIVE

To evaluate whether stool culture improves the diagnosis of TB in people living with the human immunodeficiency virus (PLHIV).

DESIGN

We analysed cross-sectional data of TB diagnosis in PLHIV in Cambodia, Thailand and Viet Nam. Logistic regression was used to assess the association between positive stool culture and TB, and to calculate the incremental yield of stool culture.

RESULTS

A total of 1693 PLHIV were enrolled with a stool culture result. Of 228 PLHIV with culture-confirmed TB from any site, 101 (44%) had a positive stool culture; of these, 91 (90%) had pulmonary TB (PTB). After adjusting for confounding factors, a positive stool culture was associated with smear-negative (odds ratio [OR] 26, 95% confidence interval [CI] 12-58), moderately smear-positive (OR 60, 95%CI 23-159) and highly smear-positive (OR 179, 95%CI 59-546) PTB compared with no PTB. No statistically significant association existed with extra-pulmonary TB compared with no extra-pulmonary TB (OR 2, 95%CI 1-5). The incremental yield of one stool culture above two sputum cultures (5%, 95%CI 3-8) was comparable to an additional sputum culture (7%, 95%CI 4-11).

CONCLUSION

Nearly half of the PLHIV with TB had a positive stool culture that was strongly associated with PTB. Stool cultures may be used to diagnose TB in PLHIV.

Molecular characterization of extended spectrum beta-lactamase among clinical isolates Escherichia coli and Klebsiella pneumoniae

BACKGROUND

Resistance to beta-lactams has been increasing in the treatment of infections caused by Escherichia coli and Klebsiella pneumoniae. The production of extended-spectrum beta-lactamases (ESBLs), that hydrolyze extended-spectrum cephalosporins, is the major cause of beta-lactam resistance.

OBJECTIVE

To determine the prevalence and characterize of ESBLs produced by E. coli and K. pneumoniae from clinical specimens.

MATERIAL AND METHOD

ESBLs were determined by disk diffusion test, double disk synergy test, and E-test ESBLs. All ESBLs producing isolates were investigated for the presence of bla(TEM) bla(SHV), bla(CTX-M) and bla(VEB) genes by polymerase chain reaction (PCR). Nucleotide sequencing of bla(TEM) and bla(SHV) were performed E. coli and K. pneumoniae were isolated from clinical specimens of patients in King Chulalongkorn Memorial Hospital between February and May 2002. Of the 270 isolates, 212 were E. coli and 58 were K. pneumoniae.

RESULTS

ESBL roduction was detected in 17% (36/212) of E. coli and 34.5% (20/58) of K. pneumoniae isolates. Of the 20 K. pneumoniae isolates, the beta-lactamase genes were bla(SHV) (18/20, 90%), bla(TEM) (10/20, 50%), bla(VEB-like) (6/20, 30%) and bla(CTX-M-like) (3/20, 15%). Thirty-six E. coli isolates carried bla(TEM) bla(CTX-M-like) and bla(VEB-like) genes in 72.2% (26/36), 52.8% (19/36) and 16.7% (6/36), respectively Bla(SHV) was not detected in ESBL-producing E. coli, whereas it predominated in K. pneumoniae. Of the 56 ESBL producing isolates, 30 (53.6%) coharboured at least two different bla genes. All TEM identified were TEM-1B, which is not an ESBL. CTX-M ESBLs were the most common in E. coli.

CONCLUSION

The double disk diffusion test should be added routinely in the antibiotic susceptibility test for the Enterobacteriaceae. It is simple to perform, easy to interpret, and economical. The presence of bla(CTX-M) and bla(VEB) in ESBL-producing E. coli and K. pneumoniae indicates the high prevalence of these genes in Thailand.

Inadequate ventilation for nosocomial tuberculosis prevention in public hospitals in Central Thailand

SETTING

Forty-two community and general hospitals in central Thailand.

OBJECTIVE

To examine the adequacy of indoor ventilation for nosocomial tuberculosis (TB) prevention in public hospitals in central Thailand.

DESIGN

A cross-sectional survey was conducted among 323 patient care and ancillary areas in the target hospitals. Data on indoor ventilation rate were collected by the tracer gas method and reported as air changes per hour (ACH). The adequacy of the measured ventilation rates were then determined by comparison with the international recommended standard values.

RESULTS

Indoor ventilation rates were inadequate in almost half of the studied areas (144/323, 44.6%). The inadequacy was particularly serious in the emergency rooms (ERs) and radiological areas, where 73.8% (31/42 each) of the rooms had ACH below the recommended standards. Detailed analysis showed that most of the rooms with natural ventilation had air exchange rates that exceeded the recommended standards, while the opposite was the case for rooms with air-conditioning, particularly the window or wall-mount type.

CONCLUSION

Indoor ventilation in high-risk nosocomial TB areas in public hospitals in Thailand was inadequate due to the installation of air-conditioning systems in modern buildings.

Amplification of P1 gene by polymerase chain reaction for detection of Mycoplasma pneumoniae

Mycoplasma pneumoniae is a causative agent of human respiratory tract infection of which the clinical features are not significantly different from those of infections caused by other respiratory pathogens. The diagnosis is based principally on laboratory tests. Since conventional methods such as culture and serological tests are time-consuming, insensitive, and non-specific, polymerase chain reaction (PCR) was employed for laboratory diagnostics. This study was aimed to develop PCR method to detect M. pneumoniae by designing primers to amplify fragment of the P1 adhesin gene. Two protocols, PCR-probe hybridization and nested PCR, were carried out. False-positive result due to amplicon carry over was prevented by using dUTP instead of dTTP and the addition of enzyme uracil DNA glycosylase (UDG). For nested PCR, UDG was added only in the first round reaction mixture. The sensitivity of PCR was 10 fg of M, pneumoniae DNA as detected by agarose gel electrophoresis and increased to be 1 fg as detected by either probe hybridization or nested PCR. The specificity of PCR was tested with DNAs from Mycoplasma spp, a variety of different bacterial genera and human leukocyte. All gave negative results. Considering of the speed, sensitivity, specificity and the prevention of amplicon carryover, the developed PCR-based protocols were suitable and reliable for the detection of M. pneumoniae in routine laboratory.

A more reliable PCR for detection of Mycobacterium tuberculosis in clinical samples

Diagnostic techniques based on PCR have two major problems: false-positive reactions due to contamination with DNA fragments from previous PCRs (amplicons) and false-negative reactions caused by inhibitors that interfere with the PCR. We have improved our previously reported PCR based on the amplification of a fragment of the Mycobacterium tuberculosis complex-specific insertion element IS6110 with respect to both problems. False-positive reactions caused by amplicon contamination were prevented by the use of uracil-N-glycosylase and dUTP instead of dTTP. We selected a new set of primers outside the region spanned by the formerly used primers to avoid false-positive reactions caused by dTTP-containing amplicons still present in the laboratory. With this new primer set, 16 copies of the IS6110 insertion element, the equivalent of two bacteria, could be amplified 10(10) times in 40 cycles, resulting in a mean efficiency of 77% per cycle. To detect the presence of inhibitors of the Taq polymerase, which may cause false-negative reactions, part of each sample was spiked with M. tuberculosis DNA. The DNA purification method using guanidinium thiocyanate and diatoms effectively removed most or all inhibitors of the PCR. However, this was not suitable for blood samples, for which we developed a proteinase K treatment followed by phenol-chloroform extraction. This method permitted detection of 20 M. tuberculosis bacteria per ml of whole blood. Various laboratory procedures were introduced to reduce failure or inhibition of PCR and avoid DNA cross contamination. We have tested 218 different clinical specimens obtained from patients suspected of having tuberculosis. The samples included sputum (n=145), tissue biopsy samples (n=25), cerebrospinal fluid (n=15), blood (n=14), pleural fluid (n=9), feces, (n=7), fluid from fistulae (n=2), and pus from a wound (n=1). The results obtained by PCR were consistent with those obtained with culture, which is the "gold standard." We demonstrate that PCR is a useful technique for the rapid diagnosis of tuberculosis at various sites.