Comparison of molecular detection methods for pertussis in children during a state-wide outbreak

Identification of etiologic agents and clinical characteristics for patients suspected of having pertussis in a large Children's Hospital in China

BACKGROUND

In China, pertussis is a major health problem with an increasing incidence despite immunization efforts. Timely and accurate diagnosis is essential for the optimal management of pertussis, especially in severe cases.

METHODS

Nasopharyngeal swabs or sputum specimens were obtained from patients suspected of having pertussis on the day of hospitalization at Shanghai Children's Medical Center from December 01, 2016, to November 30, 2017. The specimens were tested with the FilmArray Respiratory Panel, a multiplex polymerase chain reaction (PCR) assay that detects 16 viruses, Bordetella pertussis (B. pertussis), Mycoplasma pneumoniae (M. pneumoniae), and Chlamydophila pneumoniae (C. pneumoniae).

RESULTS

Among the 140 children studied, 50.0% (70/140) were detected with a single pathogen, 45.0% (63/140) were detected with multiple pathogens, and 5.0% (7/140) had no detected pathogens. Forty-nine (35%, 49/140) patients tested positive for B. pertussis. Respiratory syncytial virus (RSV), parainfluenza virus (Para) and rhinovirus/enterovirus (Rhino/Entero) were the most prevalent pathogens in patients with pertussis-like syndrome. No significant differences between the groups with pertussis and pertussis-like syndrome were observed regarding the clinical symptoms. Severe cases were more frequently observed in unvaccinated, premature and pertussis/RSV co-infection patients.

CONCLUSIONS

Our study highlights the importance of the timely and accurate diagnosis of pertussis based on both clinical symptoms and laboratory methods.

Clinical-epidemiological study of Bordetella pertussis infection in the Gran Canaria island in the period, 2008-2016

OBJECTIVE

Describe the epidemiological and clinical pattern of Bordetella pertussis infection (whooping cough) among hospitalised infants less than one year-old in a paediatric hospital in Gran Canaria.

PATIENTS AND METHODS

A retrospective review of the patient hospital records was performed, and recording only those with a microbiological diagnosis of pertussis infection detected using polymerase chain reaction, from January 2008 to December 2016.

RESULTS

A total of 110 patients were identified, of which 105 (95.4%) were less than 6 months old, and 59.1% were males. The annual incidence of hospital admissions was estimated between 13.7 and 425.0 cases per 100 000 infants <12 months old, with 2 peaks in 2011 and 2015. Household members were the main potential sources of infection. Main clinical features were pertussis cough associated with signs of catarrh, cyanosis, and lymphocytosis. Complications occurred in 15.4% of the patients (mainly pneumonia), but the outcome was favourable in all the cases. A lower age and non-vaccination were associated with an increased risk of developing complications (p < .05). Viral co-infection occurred in 31.6% of infants diagnosed with pertussis.

CONCLUSIONS

The incidence of pertussis has increased in the last years in Gran Canaria, with a lower development of complications and mortality rates compared with the previous period. Lower age and non-vaccination status are considered risk factors for developing complications. Vaccination in pregnant women will probably lead to a decline in the incidence in the future, especially in infants younger than 6 months.

[Clinical-epidemiological study of Bordetella pertussis infection in the Gran Canaria island in the period, 2008-2016]

OBJECTIVE

Describe the epidemiological and clinical pattern of Bordetella pertussis infection (whooping cough) among hospitalised infants less than one year-old in a paediatric hospital in Gran Canaria.

PATIENTS AND METHODS

A retrospective review of the patient hospital records was performed, and recording only those with a microbiological diagnosis of pertussis infection detected using polymerase chain reaction, from January 2008 to December 2016.

RESULTS

A total of 110 patients were identified, of which 105 (95.4%) were less than 6 months-old, and 59.1% were males. The annual incidence of hospital admissions was estimated between 13.7 to 425.0 cases per 100,000 infants <12 months old, with 2peaks in 2011 and 2015. Household members were the main potential sources of infection. Main clinical features were pertussis cough associated with signs of catarrh, cyanosis, and lymphocytosis. Complications occurred in 15.4% of the patients (mainly pneumonia), but the outcome was favourable in all the cases. A lower age and non-vaccination were associated with an increased risk of developing complications (P<.05). Viral co-infection occurred in 31.6% of infants diagnosed with pertussis.

CONCLUSIONS

The incidence of pertussis has increased in the last years in Gran Canaria, with a lower development of complications and mortality rates compared with the previous period. Lower age and non-vaccination status are considered risk factors for developing complications. Vaccination in pregnant women will probably lead to a decline in the incidence in the future, especially in infants younger than 6 months.

Interpretation and Relevance of Advanced Technique Results

Advanced techniques in the field of diagnostic microbiology have made amazing progress over the past 25 years due largely to a technological revolution in the molecular aspects of microbiology [1, 2]. In particular, rapid molecular methods for nucleic acid amplification and characterization combined with automation in the clinical microbiology laboratory as well as user-friendly software and robust laboratory informatics systems have significantly broadened the diagnostic capabilities of modern clinical microbiology laboratories. Molecular methods such as nucleic acid amplification tests (NAATs) rapidly are being developed and introduced in the clinical laboratory setting [3, 4]. Indeed, every section of the clinical microbiology laboratory, including bacteriology, mycology, mycobacteriology, parasitology, and virology, has benefited from these advanced techniques. Because of the rapid development and adaptation of these molecular techniques, the interpretation and relevance of the results produced by such molecular methods continues to lag behind. The purpose of this chapter is to review, update, and discuss the interpretation and relevance of results produced by these advanced molecular techniques.

Nucleic acid amplification methodologies for the detection of pulmonary mold infections

INTRODUCTION

The detection of pulmonary mold infections has historically required technically demanding methods obtained through invasive procedures. Nucleic acid amplification assays have the potential to circumvent the technical hurdles associated with diagnosis, but are not without potential pitfalls. Areas covered: In this paper, the authors review new assays for the diagnosis of pulmonary mold infections due to aspergillosis, mucormycosis, and hyalohyphomycoses as well as uncommon infections caused by dematiaceous molds. Expert commentary: Nucleic acid amplification assays have the potential to rapidly identify patients with invasive mycoses and could shorten the time to implementation of appropriate antimicrobial therapy. However, selection of appropriate patient populations will be crucial to ensure the highest Bayesian positive predictive value for any novel diagnostic platform.

Population-Based Pertussis Incidence and Risk Factors in Infants Less Than 6 Months in Nepal

BACKGROUND.

Pertussis is estimated to cause 2 percent of childhood deaths globally and is a growing public health problem in developed countries despite high vaccination coverage. Infants are at greatest risk of morbidity and mortality. Maternal vaccination during pregnancy may be effective to prevent pertussis in young infants, but population-based estimates of disease burden in infants are lacking, particularly in low-income countries. The objective of this study was to estimate the incidence of pertussis in infants less than 6 months of age in Sarlahi District, Nepal.

METHODS.

Nested within a population-based randomized controlled trial of influenza vaccination during pregnancy, infants were visited weekly from birth through 6 months to assess respiratory illness in the prior week. If any respiratory symptoms had occurred, a nasal swab was collected and tested with a multitarget pertussis polymerase chain reaction (PCR) assay. The prospective cohort study includes infants observed between May 2011 and August 2014.

RESULTS.

The incidence of PCR-confirmed Bordetella pertussis was 13.3 cases per 1000 infant-years (95% confidence interval, 7.7-21.3) in a cohort of 3483 infants with at least 1 day of follow-up.

CONCLUSIONS.

In a population-based active home surveillance for respiratory illness, a low risk for pertussis was estimated among infants in rural Nepal. Nepal's immunization program, which includes a childhood whole cell pertussis vaccine, may be effective in controlling pertussis in infants.