Aetiology of childhood pneumonia in low- and middle-income countries in the era of vaccination: a systematic review

Respiratory adenovirus infections in children: a focus on Africa

PURPOSE OF REVIEW

Lower respiratory tract infections (LRTIs) are an important cause of child morbidity and mortality globally, especially in children under the age of 5 years in Africa. Respiratory viruses, including human adenoviruses (HAdVs), are common causes of LRTIs in children. This review aims to shed light on the epidemiology, clinical manifestations, sequelae, and treatment options specific to adenovirus respiratory infections in African children.

RECENT FINDINGS

Recent evidence has challenged the perception that adenovirus is a negligible cause of LRTIs. Studies show HAdV emerging as the third most common viral pathogen in fatal pneumonias among under-5 children in low-income and middle-income African countries, contributing to 5.5% of all pneumonia deaths and ranking second in hospital-associated viral pneumonia deaths. Predominant HAdV serotypes associated with disease differ by country and region, and have changed over time. Risk factors for increased disease severity and long-term respiratory sequelae in previously healthy African children with HAdV LRTIs are not well established.

SUMMARY

Although respiratory viruses, including HAdV, are recognized contributors to LRTIs, the prevalence and impact of adenovirus infections have been under-recognized and understated. Available data suggests that African children, particularly those under 5 years old, are at risk of severe sequelae from respiratory HAdV infections. Long-term sequelae, including bronchiectasis and postinfectious bronchiolitis obliterans, further underscore the significant impact of HAdV infections. However, the scarcity of comprehensive data hampers our understanding of the extent of the impact of HAdV infections on child lung health in Africa. We recommend scaled-up HAdV surveillance, ensuring its consistent inclusion in population-level LRTI assessments, and expanded and equitable access to diagnostics for early recognition of African children at risk of developing chronic sequelae and death. Enhanced understanding of adenovirus epidemiology and clinical outcomes and the availability of therapeutic options are essential for informed public health strategies and clinical care.

Predictors of Respiratory Syncytial Virus, Influenza Virus, and Human Metapneumovirus Carriage in Children Under 5 Years With WHO-Defined Fast-Breathing Pneumonia in Pakistan

BACKGROUND

Pneumonia is a leading cause of morbidity and mortality in children < 5 years. We describe nasopharyngeal carriage of respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and influenza virus among children with fast-breathing pneumonia in Karachi, Pakistan.

METHODS

We performed a cross-sectional analysis of nasopharyngeal swabs from children aged 2-59 months with fast-breathing pneumonia, enrolled in the randomized trial of amoxicillin versus placebo for fast-breathing pneumonia (RETAPP) (NCT02372461) from 2014 to 2016. Swabs were collected using WHO standardized methods, processed at the Aga Khan University, Pakistan. Viral detection was performed using LUMINEX xTAG respiratory viral panel assay and logistic regression identified clinical and sociodemographic predictors.

FINDINGS

Of the 1000 children tested, 92.2% (n = 922) were positive for viral carriage. RSV, hMPV, and influenza virus were detected in 59 (6.4%), 56 (6.1%), and 58 (6.3%) children and co-infections in three samples (two RSV-hMPV and one influenza-hMPV). RSV carriage was common in infants (56%), we observed a higher occurrence of fever in children with hMPV and influenza virus (80% and 88%, respectively) and fast breathing in RSV (80%) carriage. RSV carriage was positively associated with a history of fast/difficulty breathing (aOR: 1.96, 95% CI 1.02-3.76) and low oxygen saturation (aOR: 2.52, 95% CI 1.32-4.82), hMPV carriage was positively associated with a complete vaccination status (aOR: 2.22, 95% CI 1.23-4.00) and body temperature ≥ 37.5°C (aOR: 2.34, 95% CI 1.35-4.04) whereas influenza viral carriage was associated with body temperature ≥ 37.5°C (aOR: 4.48, 95% CI 2.53-7.93).

CONCLUSION

We observed a high nasopharyngeal viral carriage among children with WHO-defined fast-breathing pneumonia in Pakistan. Fever, difficulty in breathing, hypoxia and vaccination status are important clinical predictors for viral nonsevere community-acquired pneumonia.

Time-resolved RNA-seq analysis to unravel the in vivo competence induction by Streptococcus pneumoniae during pneumonia-derived sepsis

Competence development in Streptococcus pneumoniae (pneumococcus) is tightly intertwined with virulence. In addition to genes encoding genetic transformation machinery, the competence regulon also regulates the expression of allolytic factors, bacteriocins, and cytotoxins. Pneumococcal competence system has been extensively interrogated in vitro where the short transient competent state upregulates the expression of three distinct phases of "early," "late," and "delayed" genes. Recently, we have demonstrated that the pneumococcal competent state develops naturally in mouse models of pneumonia-derived sepsis. To unravel the underlying adaptive mechanisms driving the development of the competent state, we conducted a time-resolved transcriptomic analysis guided by the spatiotemporal live in vivo imaging system of competence induction during pneumonia-derived sepsis. Mouse lungs infected by the serotype 2 strain D39 expressing a competent state-specific reporter gene (D39-ssbB-luc) were subjected to RNA sequencing guided by monitoring the competence development at 0, 12, 24, and, at the moribund state, >40 hours post-infection (hpi). Transcriptomic analysis revealed that the competence-specific gene expression patterns in vivo were distinct from those under in vitro conditions. There was significant upregulation of early, late, and some delayed phase competence-specific genes as early as 12 hpi, suggesting that the pneumococcal competence regulon is important for adaptation to the lung environment. Additionally, members of the histidine triad (pht) gene family were sharply upregulated at 12 hpi followed by a steep decline throughout the rest of the infection cycle, suggesting that Pht proteins participate in the early adaptation to the lung environment. Further analysis revealed that Pht proteins execute a metal ion-dependent regulatory role in competence induction.IMPORTANCEThe induction of pneumococcal competence for genetic transformation has been extensively studied in vitro but poorly understood during lung infection. We utilized a combination of live imaging and RNA sequencing to monitor the development of a competent state during acute pneumonia. Upregulation of competence-specific genes was observed as early as 12 hour post-infection, suggesting that the pneumococcal competence regulon plays an important role in adapting pneumococcus to the stressful lung environment. Among others, we report novel finding that the pneumococcal histidine triad (pht) family of genes participates in the adaptation to the lung environment and regulates pneumococcal competence induction.

Effect of Pneumococcal Conjugate Vaccine on Pneumonia Incidence Rates among Children 2-59 Months of Age, Mongolia, 2015-2021

Starting in June 2016, the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced into the routine immunization program of Mongolia by using a 2+1 dosing schedule, phased by district. We used prospective hospital surveillance to evaluate the vaccine's effect on pneumonia incidence rates among children 2-59 months of age over a 6-year period. Of 17,607 children with pneumonia, overall adjusted incidence rate ratios showed decreased primary endpoint pneumonia, very severe pneumonia, and probable pneumococcal pneumonia until June 2021. Results excluding and including the COVID-19 pandemic period were similar. Pneumonia declined in 3 districts that introduced PCV13 with catch-up campaigns but not in the 1 district that did not. After PCV13 introduction, vaccine-type pneumococcal carriage prevalence decreased by 44% and nonvaccine-type carriage increased by 49%. After PCV13 introduction in Mongolia, the incidence of more specific pneumonia endpoints declined in children 2-59 months of age; additional benefits were conferred by catch-up campaigns.

Imaging of Acute Complications of Community-Acquired Pneumonia in the Paediatric Population-From Chest Radiography to MRI

The most common acute infection and leading cause of death in children worldwide is pneumonia. Clinical and laboratory tests essentially diagnose community-acquired pneumonia (CAP). CAP can be caused by bacteria, viruses, or atypical microorganisms. Imaging is usually reserved for children who do not respond to treatment, need hospitalisation, or have hospital-acquired pneumonia. This review discusses the imaging findings for acute CAP complications and the diagnostic role of each imaging modality. Pleural effusion, empyema, necrotizing pneumonia, abscess, pneumatocele, pleural fistulas, and paediatric acute respiratory distress syndrome (PARDS) are acute CAP complications. When evaluating complicated CAP patients, chest radiography, lung ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) can be used, with each having their own pros and cons. Imaging is usually not needed for CAP diagnosis, but it is essential for complicated cases and follow-ups. Lung ultrasound can supplement chest radiography (CR), which starts the diagnostic algorithm. Contrast-enhanced computed tomography (CECT) is used for complex cases. Advances in MRI protocols make it a viable alternative for diagnosing CAP and its complications.

Causes of sudden neonatal mortality disclosed by autopsy and histopathological examination

The neonatal period, or the first 28 days of life, is the most vulnerable time in a child's life. Neonatal mortality has decreased in recent years. However, this progress varies at the national level, which necessitates actual regional data from different countries to identify local handicaps for life-saving precautions. This study aimed to investigate the causes for neonatal deaths as revealed by autopsy and histopathological examinations. A retrospective cross-sectional study was designed to identify the main causes of neonatal deaths in children who were autopsied at our institution between January 1, 2014, and December 31, 2021. Children who died within the first 28 days after birth (1-28 days of age) were referred to as neonatal cases. The main causes of neonatal death in children were determined via autopsy and histopathological and toxicological examinations. Furthermore, the causes of death were classified according to their manner of death. During this period, 122 neonatal children were autopsied at our institution. This group comprised 57 girls and 65 boys. For the manner of the death, natural causes were the most common cause (n = 91, 74.5%). Among natural causes, pneumonia (n = 66) was the leading one, representing 54% of all neonatal deaths, followed by perinatal conditions (n = 16, 13.1%). One of the pioneering reasons for death was sudden, unexpected postnatal collapse (n = 24, 19.6%), which was categorized under the undetermined group considering the manner of death. Unintentional (accidental) deaths accounted for 0.8% (n = 1) of total deaths, and intentional deaths were responsible for 6 neonates (4.9%) losses. This study shows that newborn children still die from simple and treatable infectious causes, probably arising from various familial and/or public inadequacies. In addition, sudden and unexpected postnatal collapse remains an important cause of neonatal mortality that has yet to be fully resolved. This study points out valuable inferences for caregivers and competent authorities to take preventive measures to prevent avoidable neonatal deaths.

Salivary Biomarkers to Differentiate between Streptococcus pneumoniae and Influenza A Virus-Related Pneumonia in Children

Community-acquired pneumonia (CAP) is common among children and can be fatal in certain conditions. In children, CAP can be caused by viral or bacterial infections. Identification of pathogens can help select appropriate therapeutic strategies. Salivary analysis may be a potential diagnostic tool because it is noninvasive, patient-friendly, and easy to perform in children. A prospective study was conducted in children with pneumonia admitted to a hospital. Salivary samples from patients with definite Streptococcus pneumoniae and influenza A strains were used for gel-free (isobaric tag for relative and absolute quantitation (iTRAQ)) proteomics. No statistically significant difference was detected in salivary CRP levels between Streptococcus pneumoniae and influenza A pneumonia in children. Several potential salivary biomarkers were identified using gel-free iTRAQ proteomics to differentiate pneumonia from Streptococcus pneumoniae or influenza A virus infections in pediatric patients. ELISA validated that Streptococcus pneumoniae group has a higher abundance of salivary alpha 1-antichymotrypsin than those in the influenza A group. Whether these salivary biomarkers can be used to distinguish other bacteria from viral pneumonia requires further verification.

Bronchiolitis versus bronchopneumonia: navigating antibiotic use within the LRTI spectrum

Bronchiolitis, a common reason for infant hospitalisation in South Africa (SA), is caused by viral pathogens. Bronchiolitis is typically an illness of mild to moderate severity that occurs in well-nourished children. Hospitalised SA infants frequently have severe disease and/or coexisting medical conditions, and these cases of bronchiolitis may have bacterial co-infection that requires antibiotic therapy. However, the existence of widespread antimicrobial resistance in SA warrants the judicious use of antibiotics. This commentary describes: (i) common clinical pitfalls leading to an incorrect diagnosis of bronchopneumonia; and (ii) considerations for antibiotic therapy in hospitalised infants with bronchiolitis. If antibiotics are prescribed, the indication for their use should be clearly stated, and antibiotic therapy must be stopped promptly if investigations indicate that bacterial co-infection is unlikely. Until more robust data emerge, we recommend a pragmatic management strategy to inform antibiotic use in hospitalised SA infants with bronchiolitis in whom bacterial co-infection is suspected.

The dilemma of improving rational antibiotic use in pediatric community-acquired pneumonia

Pneumonia is the number one cause of disease and deaths in children under five years old, outside the neonatal period, with the greatest number of cases reported from resource-limited settings. The etiology is variable, with not much information on the local etiology drug resistance profile in many countries. Recent studies suggest an increasing contribution from respiratory viruses, also in children with severe pneumonia, with an increased relative contribution in settings that have good vaccine coverage against common bacterial pathogens. Respiratory virus circulation was greatly reduced during highly restrictive measures to contain the spread of COVID-19 but rebounded once COVID-19 restrictions were relaxed. We conducted a comprehensive literature review of the disease burden, pathogens, case management and current available prevention of community acquired childhood pneumonia, with a focus on rational antibiotic use, since the treatment of respiratory infections is the leading cause of antibiotic use in children. Consistent application of revised World Health Organisation (WHO) guidance that children presenting with coryzal symptoms or wheeze can be managed without antibiotics in the absence of fever, will help to reduce unnecessary antibiotic use, as will increased availability and use of bedside inflammatory marker tests, such as C-reactive protein (CRP) in children with respiratory symptoms and fever.

Nasopharyngeal aspirates in children with severe community-acquired pneumonia collected within 3 days before bronchoscopy can partially reflect the pathogens in bronchoalveolar lavage fluids

BACKGROUND

There is little evidence about consistency between nasopharyngeal and pulmonary pathogens in children with severe pneumonia. This study aims to compare the difference of pathogens between nasopharyngeal aspirates (NPAs) collected before bronchoscopy and bronchoalveolar lavage fluids (BALFs) in children with severe community-acquired pneumonia (SCAP).

METHODS

NPAs and BALFs were collected form pediatric SCAP cases hospitalized from January 2018 to March 2019. NPAs were colleced within 3 days before bronchoscopy. Samples were detected by direct immunofluorescence assay (DFA) for seven respiratory viruses and by routine bacterial culture in the clinical microbiology laboratory. Respiratory syncytial virus (RSV), Adenovirus (ADV), Influenza virus types A, B (IV-A and IV-B), Parainfluenza virus 1-3 (PIV1-3) were detected with a commercial assay. The virological and bacteriological detention results of NPAs were compared with the results of BALFs.

RESULTS

In total 204 cases with mean age of 3.4 ± 2.8 years (IQR, 1 month-14 years) were included in the study. Both NPA and BALF were collected from those cases. The positive rates of pathogen in NPAs and BALFs were 25.0% (51/204) and 36.7% (75/204), respectively (x² = 6.614, P = 0.010). Respiratory viruses were found in 16.1% (33/204) from NPAs and 32.3% (66/204) from BALFs (x² = 14.524, P < 0.001). RSV and ADV were the two most frequent detected viruses in NPAs and BALFs. High consistentcy of pathogens between NPAs and BALFs was observed, and 96.9% (32/33) viruses detected in NPAs were also found in BALFs. While bacteria were isolated from 12.7% (26/204) and 10.7% (22/204) of the two kinds of samples, respectively (x² = 0.378, P = 0.539). In addition, Haemophilus influenzae (HI) was the dominant germ in both samples.

CONCLUSION

The DFA method used to detect seven respiratory viruses from NPAs collected within 3 days before bronchoscopy can partially reflect the pathogens in the lungs in children with SCAP.

A systematic review of clinical, epidemiological and demographic predictors of tuberculosis in children with pneumonia

Background

Tuberculosis (TB) can present as acute, severe pneumonia in children, but features which distinguish TB from other causes of pneumonia are not well understood. We conducted a systematic review to determine the prevalence and to explore clinical and demographic predictors of TB in children presenting with pneumonia over three decades.

Methods

We searched for peer-reviewed, English language studies published between 1990 and 2020 that included children aged between 1 month and 17 years with pneumonia and prospectively evaluated for TB. There were 895 abstracts and titles screened, and 72 full text articles assessed for eligibility.

Results

Thirteen clinical studies, two autopsy studies and one systematic review were included in analyses. Majority of studies were from Africa (12/15) and included children less than five years age. Prevalence of bacteriologically confirmed TB in children with pneumonia ranged from 0.2% to 14.8% (median = 3.7%, interquartile range (IQR) = 5.95) and remained stable over the three decades. TB may be more likely in children with pneumonia if they have a history of close TB contact, HIV infection, malnutrition, age less than one year or failure to respond to empirical antibiotics. However, these features have limited discriminatory value as TB commonly presents as acute severe pneumonia – with a short duration of cough, and clinical and radiographic features indistinguishable from other causes of pneumonia. Approximately half of patients with TB respond to initial empirical antibiotics, presumably due to bacterial co-infection, and follow-up may be critical to detect and treat TB.

Conclusion

TB should be considered as a potential cause or comorbidity in all children presenting with pneumonia in high burden settings. Clinicians should be alert to the presence of known risk factors for TB and bacteriological confirmation sought whenever possible. Quality data regarding clinical predictors of TB in childhood pneumonia are lacking. Further, prospective research is needed to better understand predictors and prevalence of TB in childhood pneumonia, particularly in TB endemic settings outside of Africa and in older children. Children of all ages with pneumonia should be included in research on improved, point-of-care TB diagnostics to support early case detection and treatment.