Acceptability of sputum specimens for diagnosing pulmonary tuberculosis

Correlation of Cyclic Threshold Values Generated by GeneXpert Ultra MTB/RIF and Fluorescence Microscopy to Predict Mycobacterial Burden in Suspected Cases of Pulmonary Tuberculosis

BACKGROUND

Smear microscopy for acid-fast bacilli visualization is important to assess the infectivity rate in patients with pulmonary tuberculosis (PTB), but it has limited sensitivity; hence, it is important to find an alternative strategy. The aim of our study was to compare the fluorescence microscopy grading by Auramine O phenol staining technique of respiratory samples with the cyclic threshold (Ct) values of GeneXpert Ultra (Mycobacterium tuberculosis/rifampicin [MTB/RIF]) and assess the diagnostic efficacy of GeneXpert Ultra (MTB/RIF) compared to microscopy in suspected cases of PTB.

METHODS

The study was conducted in the Mycobacteriology Laboratory, Department of Microbiology, in Kasturba Hospital, Manipal. The study was a prospective, single-centered, cross-sectional study. Four hundred and fifty-two respiratory samples were included in the study. An optimal Ct cutoff value for ruling smear-positivity and smear-negativity and the mean Ct cutoff value were calculated. Clinical and radiological data from the requisition forms were assessed. IBM SPSS statistics software version 22 was used. The correlation between GeneXpert Ultra (MTB/RIF) Ct values and smear status was calculated by polychoric correlation. The extended McNemar's test was used to find the association between the variables.

RESULTS

GeneXpert Ultra (MTB/RIF) yielded a higher positivity rate of 22.2% compared to smear microscopy 17.2%. Ct value and smear grading yielded a positive correlation (P = 0.8681; P < 0.05). GeneXpert Ultra (MTB/RIF) yielded nontuberculous mycobacteria in five undetected cases and speciated as Mycobacterium abscessus complex.

CONCLUSIONS

Our study confirms the GeneXpert Ultra (MTB/RIF) Ct value levels as a predictor of smear positivity.

Diagnostic performance of an in-house multiplex PCR assay and the retrospective surveillance of bacterial respiratory pathogens at a teaching hospital, Kelantan, Malaysia

Respiratory tract infections (RTIs), including pneumonia and pulmonary tuberculosis, are among the leading causes of death worldwide. The use of accurate diagnostic tests is crucial to initiate proper treatment and therapy to reduce the mortality rates for RTIs. A PCR assay for simultaneous detection of six respiratory bacteria: Haemophilus influenzae, Klebsiella pneumoniae, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae, was developed in our lab. The current study aimed to evaluate the performance of this assay along with the retrospective surveillance of respiratory pathogens at a teaching hospital in Kelantan, Malaysia. Leftover sputa (n = 200) from clinical laboratories were collected and undergone DNA template preparation for PCR analysis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the PCR assay were determined in comparison with the gold standard sputum culture. Overall, the accuracy performance of this assay was 94.67% (95% CI: 90.87% to 97.21%) with sensitivity, specificity, PPV and NPV of 100%, 91.67%, 87.1% and 100%, respectively. Based on the organisms detected from sputa, K. pneumoniae ranked as the top isolate (n = 48), followed by P. aeruginosa (n = 13) and H. influenzae (n = 10). Surveillance among the patients showed that the associations of bacterial positive with gender and means of acquisition were found significant (p values = 0.049 and 0.001, respectively). Besides the promising performance of this ready-to-use molecular-based assay for the rapid detection of selected bacteria pathogens, this study also highlighted significant spread of K. pneumoniae RTIs in the community.

Bacterial Species and Inflammatory Cell Variability in Respiratory Tracts of Patients with Chronic Obstructive Pulmonary Disease Exacerbation: A Multicentric Study

Background and Aim

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has profound effects on disease progression and patients' quality of life. Emerging evidence suggests an association between alterations in the respiratory microbiome flora species and airway inflammation in patients with AECOPD. The present study aimed to describe the inflammatory cells and bacterial microbiome distributions in respiratory tract in Egyptian patients with AECOPD.

Subjects and Methods

The present cross-sectional study included 208 patients with AECOPD. Sputum and broncho-alveolar lavage samples from the studied patients were submitted to microbial cultures using appropriate media. Total and differential leukocytic counts and were done via automated cell counter.

Results

The present study included 208 AECOPD patients. They comprised 167 males (80.3%) and 41 females (19.7%) with an age of 57.9 ± 4.9 years. AECOPD was categorized as mild, moderate and severe in 30.8%, 43.3% and 26%, respectively. Sputum samples had significantly higher TLC, neutrophil percent and eosinophil percent when compared with BAL samples. In contrast, lymphocyte percent was significantly higher in BAL samples. Sputum specimens had significantly lower frequency of positive growths (70.2% versus 86.5%, p = 0.001). Among the identified organisms, sputum specimens had significantly lower frequency of Strept. pneumoniae (14.4% versus 30.3%, p = 0.001), Klebsiella pneumoniae (19.7% versus 31.7%, p = 0.024), Haemophilus influenzae (12.5% versus 26.9%, p = 0.011), Pseudomonas aeruginosa (2.9% versus 10%, p = 0.019) and Acinetobacter spp. (1.9% versus 7.2%, p = 0.012) growths when compared with BAL samples.

Conclusion

The present study could identify a distinctive pattern of inflammatory cell distribution in sputum and BAL samples of AECOPD patients. The most commonly isolated organisms were Klebsiella pneumoniae and Strept. pneumoniae.

Predominance of Other Pathogenic Bacteria among Presumptive Tuberculosis Cases Attending Tuberculosis Clinics in Mwanza, Tanzania: A Cross-Sectional Laboratory-Based Study

This study was designed to determine the prevalence and co-infection of Mycobacterium tuberculosis and other pathogenic bacteria among presumptive cases of tuberculosis (TB) at selected hospitals in Mwanza, Tanzania. GeneXpert and conventional bacteriological culture and sensitivity were used for the detection of TB and other pathogenic bacteria, respectively. STATA version 13.0 was used for data analysis. The median (IQR) age of participants was 33 (19−51) years with males forming more than half (i.e., 59% (158/264)) of the participants. Microscopically, 29.5% (78/264) of the patients had polymorphonuclear leucocytes in the sputum samples. Approximately 7.2% (19/264), 16.3% (43/264), and 1.1% (3/264) of participants had TB, other pathogenic bacteria, and co-infections, respectively. One sample had growth of two other bacteria, resulting in a total of 44 isolated bacteria with the predominance of Gram-negative bacteria at 75.0% (33/44). The predominant species isolated was the Klebsiella pneumoniae complex at 52.3% (23/44). Overall, 27.3% (9/33) of GNB were resistant to third-generation cephalosporins, while Gram-positive bacteria were more resistant to erythromycin at 63.6% (7/11). Good quality sputa had a significantly higher yield of pathogenic bacteria than poor quality sputa (37.2% vs. 7.5%, p < 0.001). Presumptive TB cases were predominantly infected with other pathogenic bacteria than M. tuberculosis. Therefore, other pathogenic bacteria should be considered when attending presumptive TB cases to ensure favorable treatment outcomes.

Development of a multiplex real-time PCR assay for the simultaneous detection of four bacterial pathogens causing pneumonia

Classification of clinical symptoms and diagnostic microbiology are essential to effectively employ antimicrobial therapy for lower respiratory tract infections (LRTIs) in a timely manner. Empirical antibiotic treatment without microbial identification hinders the selective use of narrow-spectrum antibiotics and effective patient treatment. Thus, the development of rapid and accurate diagnostic procedures that can be readily adopted by the clinic is necessary to minimize non-essential or excessive use of antibiotics and accelerate patient recovery from LRTI-induced damage. We developed and validated a multiplex real-time polymerase chain reaction (mRT-PCR) assay with good analytical performance and high specificity to simultaneously detect four bacterial pathogens causing pneumonia: Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Moraxella catarrhalis. The analytical performance of mRT-PCR against target pathogens was evaluated by the limit of detection (LOD), specificity, and repeatability. Two hundred and ten clinical specimens from pneumonia patients were processed using an automatic nucleic acid extraction system for the “respiratory bacteria four” (RB4) mRT-PCR assay, and the results were directly compared to references from bacterial culture and/or Sanger sequencing. The RB4 mRT-PCR assay detected all target pathogens from sputum specimens with a coefficient of variation ranging from 0.29 to 1.71 and conservative LOD of DNA corresponding to 5 × 10² copies/reaction. The concordance of the assay with reference-positive specimens was 100%, and additional bacterial infections were detected from reference-negative specimens. Overall, the RB4 mRT-PCR assay showed a more rapid turnaround time and higher performance that those of reference assays. The RB4 mRT-PCR assay is a high-throughput and reliable tool that assists decision-making assessment and outperforms other standard methods. This tool supports patient management by considerably reducing the inappropriate use of antibiotics.

Utilidad de los criterios de Murray para el procesamiento de esputo en pacientes con fibrosis quística. Laboratorio de Infectados de la Universidad de Antioquia (Medellín/Colombia)

Introducción: la fibrosis quística (FQ) es una enfermedad autosómica recesiva que aumenta la viscosidad de las secreciones, en especial las del árbol respiratorio; genera inflamación crónica y colonización/infección por microorganismos, conduciendo a deterioro de la función pulmonar y muerte. Nuestro estudio evaluó la calidad del esputo de pacientes con FQ que ingresaron al Laboratorio de Infectados de la UdeA con base a los criterios de Murray. Metodología: estudio descriptivo con información retrospectiva, incluyendo todos los esputos de pacientes con FQ, recolectados entre enero de 2015 a diciembre de 2018. Resultados: se analizaron 686 muestras de 85 pacientes, de las cuáles se obtuvo cultivo positivo en 501 (73 %) y el 21 % no cumplían los criterios de calidad según Murray. De 908 aislamientos identificados, 823 (90.6 %) corresponden a microorganismos considerados como patógenos en la vía aérea de los pacientes con FQ donde se incluyen S aureus, Pseudomonas spp, H influenzae, Burkhordelia spp, A. xylosoxidans, S maltophilia, A fumigatus, entre otras. Conclusiones: los criterios de Murray no se deben utilizar para definir el procesamiento o no del esputo en pacientes con FQ.

Evaluation of continuous quality improvement of tuberculosis and HIV diagnostic services in Amhara Public Health Institute, Ethiopia

Background

Unreliable laboratory results lead to unnecessary tests, procedures or treatments which may harm the patient. Continuous quality improvement (CQI) is a useful objective tool to improve processes and services. The use of quality indicators that meet requirements for effectiveness is an important quality improvement tool. However, the quality of critical aspects of pre-examination, examination, and post-examination processes have not been evaluated in Ethiopia including our setting. Hence, this study aimed to assess the performance of continuous quality improvement of TB and HIV laboratory tests in the Amhara Public Health Institute (APHI).

Methods

A cross-sectional study was conducted to evaluate the quality indicators of advanced TB and HIV related laboratory tests in APHI from 01 January to 30 September 2019. HIV viral load, exposed infant diagnosis (EID), GeneXpert and TB culture quality indicators data were used as a quality improvement tool and evaluated in comparison to established targets. Data were extracted from excel database and record review of patient information, and entered and analyzed using SPSS V20 software.

Results

A total of 26,487 samples were received from 01 January to 30 September 2019. The overall specimen rejection rate was 0.43% (115/26,487). Specifically, viral load and TB culture had 0.43% and 1.14% rejection rates, respectively. The highest monthly rejection was documented for TB culture (5.3%) and viral load (2.4%) in September 2019. Centrifugation problems (46.1% [53/115]) and the use of the wrong container (40.9% [47/115]) were the main reasons for the rejections. Moreover, EID test was interrupted for a total of 54 days and 22 days due to reagent stock out and equipment down time, respectively. Similarly, about 82% of viral load and 100% of the EID tests had long turnaround time (TAT) with an average of 24.1 and 29.3 days respectively in September 2019.

Conclusions

There were high rates of TB culture and viral load specimen rejection, and EID test interruptions. The TAT of viral load and EID tests were longer than the targeted goal (10 days) average TAT. Hence, training of sample collectors, functional equipment maintenance systems and supply chain management are recommended for continuous quality improvement.

Diagnosis of Infectious Diseases in the Lower Respiratory Tract: A Cytopathologist's Perspective

CONTEXT.—

Respiratory cytology continues to play an important role in the diagnosis of lower respiratory tract infections. Prompt, accurate diagnosis of causative organisms is of paramount importance, particularly in immunosuppressed patients. In addition, a rapidly expanding arsenal of ancillary testing is now available, aiding tremendously in organism identification.

OBJECTIVE.—

To provide an updated review on the cytomorphologic features of common organisms in lower respiratory tract infection. Relevant ancillary tests, differential diagnoses, and potential pitfalls of organism identification will also be discussed.

DATA SOURCES.—

Data for this review were gathered from PubMed searches of infectious diseases of the lower respiratory tract, especially related to the diagnoses.

CONCLUSIONS.—

The lower respiratory tract is subject to infection by a wide variety of infectious agents. Pathologists should be familiar with common organisms, including their general clinical characteristics, cytomorphologic features, differential diagnoses, and ancillary methods of detection. Above all, correlation with microbiologic and clinical information is necessary to make a confident diagnosis of infection.