The changing trend in the pattern of infective etiologies in childhood acute lower respiratory tract infection

Challenges in the Etiology and Diagnosis of Acute Febrile Illness in Children in Low- and Middle-Income Countries

Acute febrile illness is a common cause of hospital admission, and its associated infectious causes contribute to substantial morbidity and death among children worldwide, especially in low- and middle-income countries. Declining transmission of malaria in many regions, combined with the increasing use of rapid diagnostic tests for malaria, has led to the increasing recognition of leptospirosis, rickettsioses, respiratory viruses, and arboviruses as etiologic agents of fevers. However, clinical discrimination between these etiologies can be difficult. Overtreatment with antimalarial drugs is common, even in the setting of a negative test result, as is overtreatment with empiric antibacterial drugs. Viral etiologies remain underrecognized and poorly investigated. More-sensitive diagnostics have led to additional dilemmas in discriminating whether a positive test result reflects a causative pathogen. Here, we review and summarize the current epidemiology and focus particularly on children and the challenges for future research.

Blood Culture in Evaluation of Pediatric Community-Acquired Pneumonia: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Current guidelines strongly recommend collection of blood cultures (BCs) in children requiring hospitalization for presumed moderate to severe bacterial community-acquired pneumonia (CAP). Our objective was to systematically review the international pediatric literature to evaluate how often BCs are positive in hospitalized children with CAP, identify the most commonly isolated pathogens, and determine the impact of positive BCs on clinical management.

METHODS

We identified articles in PubMed and Scopus published from January 1970 through December 2013 that addressed BCs in children with CAP. We extracted total number of BCs collected and prevalence of positive BCs and used meta-regression to evaluate whether subgroups had any impact on prevalence.

RESULTS

Meta-analysis showed that the overall prevalence of positive BCs was 5.14% (95% confidence interval 3.61-7.28). Studies focusing on severe CAP had a significant effect on prevalence (P=.008), at 9.89% (95% CI 6.79-14.19) compared with 4.17% (95% confidence interval 2.79-6.18) for studies not focusing on severe CAP. The most commonly isolated organisms were Streptococcus pneumoniae (76.7%) followed by Haemophilus influenzae (3.1%) and Staphylococcus aureus (2.1%). Contaminants accounted for 14.7%. Only 3 studies reported on BC-driven change in management, with contrasting findings.

CONCLUSIONS

BCs in pediatric CAP identified organisms in only a small percentage of patients, predominantly S. pneumoniae. False-positive BC rates can be substantial. The 3 studies that examined BC-driven changes in management had conflicting results. This systematic review was limited by heterogeneous case definitions, which may overestimate the true prevalence of positive BCs in hospitalized children.

Viral etiology of hospitalized acute lower respiratory infections in children under 5 years of age -- a systematic review and meta-analysis

AIM

To estimate the proportional contribution of influenza viruses (IV), parainfluenza viruses (PIV), adenoviruses (AV), and coronaviruses (CV) to the burden of severe acute lower respiratory infections (ALRI).

METHODS

The review of the literature followed PRISMA guidelines. We included studies of hospitalized children aged 0-4 years with confirmed ALRI published between 1995 and 2011. A total of 51 studies were included in the final review, comprising 56091 hospitalized ALRI episodes.

RESULTS

IV was detected in 3.0% (2.2%-4.0%) of all hospitalized ALRI cases, PIV in 2.7% (1.9%-3.7%), and AV in 5.8% (3.4%-9.1%). CV are technically difficult to culture, and they were detected in 4.8% of all hospitalized ALRI patients in one study. When respiratory syncytial virus (RSV) and less common viruses were included, at least one virus was detected in 50.4% (40.0%-60.7%) of all hospitalized severe ALRI episodes. Moreover, 21.9% (17.7%-26.4%) of these viral ALRI were mixed, including more than one viral pathogen. Among all severe ALRI with confirmed viral etiology, IV accounted for 7.0% (5.5%-8.7%), PIV for 5.8% (4.1%-7.7%), and AV for 8.8% (5.3%-13.0%). CV was found in 10.6% of virus-positive pneumonia patients in one study.

CONCLUSIONS

This article provides the most comprehensive analysis of the contribution of four viral causes to severe ALRI to date. Our results can be used in further cost-effectiveness analyses of vaccine development and implementation for a number of respiratory viruses.

Epidemiology of invasive Haemophilus influenzae type b disease in Singapore children, 1994–2003

Invasive Haemophilus influenzae type b (Hib) diseases are major causes of childhood morbidity and mortality. For the period from 1994 to 2003, we retrospectively identified 53 children with invasive Hib disease including 31 with meningitis, 14 with pneumonia, 2 with septic arthritis, 2 with epiglottitis, 1 with neutropenic sepsis, and 3 who were bacteraemic without a focus. Two children died and 22 had serious sequelae; significantly, survivors with sequelae had presented with meningitis (P-value<0.001) or sepsis (P-value=0.001). During the 11-year period, the annual incidence of invasive Hib disease was estimated to be 4.4/100,000 children <5 years old. With rising affluence, decreasing costs of vaccines, and increased costs in caring for survivors, universal infant immunization with Hib vaccine may need to be reconsidered in Singapore.

Epidemiology, clinical characteristics and antimicrobial resistance patterns of community-acquired pneumonia in 1702 hospitalized children in Singapore

OBJECTIVE AND BACKGROUND

Childhood community-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality worldwide. The features of childhood CAP vary between countries. The aim of this study was to delineate the clinical characteristics, complications, spectrum of pathogens and patterns of antimicrobial resistance associated with hospitalized cases of childhood CAP in Singapore.

METHODS

A retrospective study was conducted of patients discharged from Singapore's only children's hospital over a 3-year period with a principal diagnosis of CAP.

RESULTS

A total of 1702 children, with a median age of 4.2 years (range: 1 month-16.3 years) were enrolled. A pathogen was identifiable in 38.4% of cases, including Mycoplasma pneumoniae in 20.3%, typical respiratory bacteria in 10.3% (64.6%Streptococcus pneumoniae; 21.7% non-typeable Haemophilus influenzae), viruses in 5.5% and mixed bacterial/viral infections in 2%. The majority of M. pneumoniae infections were in school-aged children (>5 years). Severity of infection was greater in CAP caused by typical bacteria, as reflected by length of hospital stay, CRP level, white cell and absolute neutrophil counts. Mortality from typical bacterial infections (8.9%) exceeded that from M. pneumoniae (0.3%) and viral pneumonias (0%) (P < 0.001). Aminopenicillins were often prescribed empirically for suspected S. pneumoniae and H. influenzae infections; however, resistance to these agents was frequently documented among S. pneumoniae (58.5%) and H. influenzae isolates (51%).

CONCLUSION

In Singaporean children hospitalized with CAP, M. pneumoniae is the most commonly identified causative organism, followed by common respiratory viruses, S. pneumoniae and H. influenzae. Streptococcus pneumoniae and H. influenzae are associated with greater severity of infection than other organisms, and have high levels of resistance to commonly prescribed antibiotics.

Lower respiratory tract infection in hospitalized children

OBJECTIVE

The aim of the present study was to investigate the aetiology and antibiotic-resistance patterns of community-acquired lower respiratory tract infection (LRTI) in 1999 and compare it with data from 1995 and 1988.

METHODOLOGY

A prospective observational study of LRTI in hospitalized children at KK Women's & Children's Hospital, Singapore, was undertaken.

RESULTS

A positive isolate was found in 58% of patients (671/1158), comprising viruses (n = 477, 41.2%), non-type B Haemophilus influenzae (n = 101, 8.7%), Streptococcus pneumoniae (n = 66, 5.7%), Mycoplasma pneumoniae (n = 92, 8%), Moraxella catarrhalis (n = 19, 1.6%) and other bacteria (n = 19, 1.6%). Mixed virus-bacteria (n = 104, 9%) infections were comprised mostly of virus-H. influenzae combinations. In 1999, S. pneumoniae resistance rates were penicillin 44.6% (17%, 1995), amoxycillin 3% (18%, 1995; MIC 0.5-2 microg/mL reclassified as susceptible in 1999), erythromycin 55% (30%, 1995), trimethoprim-sulfamethoxazole (TMP/SMX) 60% (23%, 1995). H. influenzaeresistance rates were amoxycillin 26.7% (38%, 1995), erythromycin 99% (37%, 1995), TMP/SMX 98% (37%, 1995). There were 15 cases of empyema of which seven were proven S. pneumoniae and there was one pneumococcal death (0.08%).

CONCLUSIONS

Pneumococcal pneumonia needs to be treated aggressively due to its high morbidity. Amoxycillin still remains useful for treating pneumococcus despite an increasing resistance to penicillin, erythromycin and TMP/SMX. Judicious use of antibiotics is needed to curb the increasing rate of antibiotic-resistance.

Respiratory morbidity of hospitalized children with Trisomy 21

OBJECTIVE

To review the respiratory morbidity in children with Trisomy 21 admitted to a teaching hospital.

METHODOLOGY

A retrospective chart review of 232 admissions to John Hunter Children's Hospital during a 6.5-year period (1991-98). The primary outcome measures included: (i) primary reason for admission, (ii) concomitant respiratory pathology, (iii) admission to the Intensive Care Unit (ICU), (iv) length of stay and (v) costs of admission.

RESULTS

Fifty-four per cent of admissions were primarily for respiratory tract pathology, dominated by pneumonia, bronchiolitis and croup. Admission to the ICU was required for 10% of admissions, most commonly for pneumonia (10/23). Congenital heart disease (CHD) was present in 33% of patients. The median length of stay and cost of admission for a child with Trisomy 21 (without CHD) with common respiratory conditions such as bronchiolitis, asthma or pneumonia was two to three times greater than in patients without Trisomy 21.

CONCLUSION

Lower respiratory pathology is most common cause for acute hospital admission in children with Trisomy 21. The presence of CHD did not influence admission rates to hospital. However, patients with CHD had longer lengths of stay, appeared to have more severe illness, were more likely to require admission to an ICU and were more likely to require ventilatory support.

Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases

Moraxella catarrhalis is an important pathogen of humans. It is a common cause of respiratory infections, particularly otitis media in children and lower respiratory tract infections in the elderly. Colonisation of the upper respiratory tract appears to be associated with infection in many cases, although this association is not well understood. Nosocomial transmission is being increasingly documented and the emergence of this organism as a cause of bacteremia is of concern. The widespread production of a beta-lactamase enzyme renders Moraxella catarrhalis resistant to the penicillins. Cephalosporins and beta-lactamase inhibitor combinations are effective for treatment of beta-lactamase producers, and the organism remains nearly universally susceptible to the macrolides, fluoroquinolones, tetracyclines and the combination of trimethoprim and sulfamethoxazole. Two major beta-lactamase forms, BRO-1 and BRO-2, have been described on the basis of their isoelectric focusing patterns. The BRO-1 enzyme is found in the majority of beta-lactamase-producing isolates and confers a higher level of resistance to strains than BRO-2. The BRO enzymes are membrane associated and their production appears to be mediated by chromosomal determinants which are transmissible by an unknown mechanism. The origin of these novel proteins is unknown.