Pneumonia in children: diagnosis, treatment and prevention

Autore: Nada El Gallad, Università degli Studi di Milano

Pneumonia is an inflammatory process affecting the parenchyma of one or both lungs. Based on clinical criteria

Pneumonia is an inflammatory process affecting the parenchyma of one or both lungs. Based on clinical criteria, pneumonia can be classified as either typical or atypical. The latter are often characterized by a more subtle and often unrecognized clinical presentation and are commonly caused by pathogens resistant to commonly used antibiotics.

Classification of pneumonia: community-acquired (CAP) and nosocomial (HAP)

Pneumonia can also be classified as community-acquired (CAP), that is lung infections contracted by healthy individuals outside a hospital setting, or nosocomial (HAP, hospital acquired pneumonia), if acquired in the hospital after at least 48 hours since the admission. These typically develop in patients with predisposing factors such as lung diseases, immunodeficiency, or ventilator exposure, and often have different etiologies, often related to multidrug-resistant (MDR) hospital pathogens.

Epidemiology, etiology, and ways of transmission of CAP and pneumonia in children

The epidemiology of CAP is significantly correlated with geographic and socio-environmental factors. In Italy, the annual incidence of pneumonia in children is estimated at 2.5 cases per 1000, with a maximum peak in the first year of life and a trend decreasing with age. These estimates are limited to hospital admissions and therefore, given that most CAP cases show a favorable course that make them manageable at home, have to be considered as underestimating the actual case incidence rate.

Main viral and bacterial causes of pneumonia in children

In children pneumonia is mainly caused by viruses or bacteria, although in about one-third of cases mixed etiology might be found (prior viral infection damaging the epithelium and bacterial superinfection). During the first two years of life, CAP is mostly caused by viruses, as a consequence of upper respiratory tract infections. The viruses that a are most commonly responsible are respiratory syncytial virus (also a common cause of bronchiolitis), influenza A and B and parainfluenza viruses, adenovirus and rhinovirus. Bacterial forms, more frequent in children in preschool and school age, identify Streptococcus pneumoniae as the main responsible agent. Other microorganisms involved are Mycoplasma pneumoniae and Chlamydia pneumoniae, less frequently Staphylococcus aureus (main responsible of severe lung infections) and, after the widespread use of the vaccine,  Haemophilus influenzae type b.

Transmission modes and risk factors

The transmission of viruses and bacteria causing pneumonia can easily occur via the airborne route, especially after sneezing and coughing in poorly ventilated and crowded environments. Blood transmission (from mother to child during delivery) is less common. Children with depressed immune system due to malnutrition, undernourishment and pre-existing diseases such as HIV/AIDS or measles, are more predisposed to infection. In most cases identifying the etiological cause is not necessary for the pediatrician, as it does not change initial therapeutic management of the disease itself.

Differences between viral and bacterial pneumonia in children. Main symptoms: fever, cough, dyspnea and chest pain

Diagnosis of CAP is essentially clinical. Pnaumonia should be suspected in all children presenting with fever and respiratory symptoms such as cough, increased work of breathing with tachypnea (age-specific pathological measures: 0-2 months >60 breaths/min, 2-12 months >50 breaths/min, 1-5 years >40 breaths/min, over 5 years >20 breaths/min) and dyspnea (intercostal and jugular retractions, nasal flaring in infants), sometimes chest pain. Abdominal pain may also be a symptom of pneumonia, in case the infection affects an area near the diaphragm or the pleura. Children often present with systemic symptoms like fatigue, poor appetite and drowsiness. Chest auscultation typically reveals crackles commonly associated with reduced air entry if the pneumonia has a localized involvement (mainly bacterial cases). In viral pneumonia, which more often have interstitial involvement, crackles can be diffused and associated with wheezing. In a child suspected of having pneumonia it is recommended measuring respiratory rate and O2 saturation with a portable oximeter. Finding tachypnea and hypoxia is an indication for hospitalization due to the need for care that cannot be provided at home.

Diagnostic tests: when to use chest X-ray and blood tests

Chest X-ray is not a routine recommended test. However, in case of diagnostic doubt, in the suspicion of complications such as pleural effusion, or in the presence of pneumonia with a prolonged course that does not respond to antibiotic therapy, imaging is the diagnostic gold standard. Chest X-ray has to be performed in preschool children who present with persistent fever, without other symptoms or specific pathological findings. Most common findings are lung consolidation (with pleural effusion in severe/complicated cases) in bacterial CAP, and increased lung content with areas of poor aeration in viral cases. In uncomplicated CAP cases that responded with complete remission to the prescribed antibiotic treatment and in which an X-ray was performed, there is no indication to repeat it. Instead, this should be reserved for children who have presented a complete lobar involvement or in cases of CAP that did not resolve or only partially resolved. Blood tests (complete blood count and evaluation of inflammation markers) are indicated in prolonged or moderate/severe cases given that, as reported by systematic reviews of the literature, no laboratory test provides decisive information for diagnosis and hence for therapy. Microbiological specific tests are generally not recommended for home-managed CAP cases because, due to their delayed results, they are not useful for the initial therapy planning.

How to treat pneumonia. Empirical treatment and antibiotic selection

Treatment of pneumonia is essentially empirical. CAP caused by different microbial agents often have a clinical presentation that overlaps with radiological and laboratory data that rarely allow differentiation between bacterial and viral etiologies and it is even less possible to distinguish among various microbial agents. Therefore, the therapeutic approach recommended by the main guidelines is to administer antibiotics to all children with CAP. About 90% of children with pneumonia can be treated at home.

Differences in pneumonia treatment in children under and over 5 years old. The one and the second antibiotic

In children aged between 2 months and 5 years, where the predominant bacterial agent is Streptococcus pneumoniae, the first-choice antibiotic is amoxicillin (with or without clavulanic acid) at a dose of 90 mg/kg/day administered in two to three doses for 7-10 days.
In cases with clinical and epidemiological suspicion of intracellular pathogen pneumonia, and when fever persists or there is only partial clinical improvement after 48-72 hours of therapy, the addition of a macrolide is recommended. In children over 5 years old, although the probability that CAP is caused by pneumococcus remains high, the likelihood of etiologies such as Mycoplasma pneumoniae and Chlamydia pneumoniae increases, therefore the first-line antibiotic are macrolides (azithromycin as a single dose of 10 mg/kg/day on the first day, to be reduced to 5 mg/kg/day for 4 other days; clarithromycin at a dose of 15 mg/kg/day in two doses for 7-10 days; erythromycin at a dose of 10 mg/kg in four daily doses for 7-10 days). In patients that show resistance to antibiotic treatment after 48-72 hours, the addition of a second antibiotic (amoxicillin or a cephalosporin) is indicated.

Indications for hospitalization for infants and children with pneumonia

10% of children with CAP require hospital admission. Hospitalization is indicated for all infants under 6 months of age who are febrile and hypoxemic, due to a strong suspicion of bacterial CAP. Hospitalization is also recommended in cases that did not respond to first-line empirical antibiotic therapy, when there is suspicion of pulmonary complications (pleural effusion or empyema, lung abscess, necrotizing pneumonia), or secondary to systemic spread of the infection (abscesses of the central nervous system, endocarditis, arthritis, septicemia, hemolytic-uremic syndrome) and in presence of the following factors: 

• Moderate to severe dyspnea;
• Oxygen saturation <90-93% in room air;
• Persistent fever beyond 72 hours after starting antibiotic therapy;
• Alteration of the state of consciousness;
• Dehydration, vomiting, inability to take medications or liquids orally;
• Pre-existing risk factors (immunodeficiency, heart diseases, chronic lung conditions);
• Poor parental compliance.

Prevention of pneumonia. Vaccination against Streptococcus pneumoniae, Haemophilus influenzae, and influenza vaccine
CAP is a relatively common manifestation or complication of infectious diseases in children that can be prevented through vaccination. In Italy, there are two preventive vaccines against pneumonia by Streptococcus pneumoniae (the most frequent case). The 13-valent conjugate vaccine is effective against the 13 strains responsible for most of the more severe infections and is administered to infants and children up to 5 years of age. The 23-valent polysaccharide vaccine is mainly used in adults. Another vaccine which use has established a large reduction in the prevalence of CAP is the one against Haemophilus influenzae (part of the hexavalent vaccine). Although not mandatory, but strongly recommended for at-risk patients categories, the influenza vaccine has proven effective in reducing the incidence of pneumonia caused by the influenza virus.

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