Pneumonia

Introduction

Pneumonia is an infection of the lungs. Other lower respiratory tract infections seen in children are croup (laryngotracheobronchitis), bronchitis, and bronchiolitis.

Pneumonia results from direct inflammation of the lung tissue. Most commonly, it is the result of infections (bacterial, viral, or fungal), but it can occur as a result of chemical injury (gastric acid/aspiration of food/hydrocarbon and lipoid pneumonia/radiation-induced pneumonia). The causative agent may reach the lung via the bloodstream or from direct inhalation

The incidence of pneumonia in developing countries in children less than 5 years old is almost 30% with a high mortality rate.

Common Causes of Pneumonia

Newborns: group B Streptococcus (GBS), respiratory syncytial virus (RSV).

Infants:
Viruses: parainfluenza viruses, influenza virus, adenovirus, and respiratory syncytial virus (RSV). cytomegalovirus

Atypical organisms: Chlamydia trachomatis, Ureaplasma urealyticum, and Pneumocystis carinii (PCP). PCP is especially seen in children with immunodeficiencies.

Bacterial: B. pertussis, Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus influenzae, mycobacterial tuberculosis.

Young children:

Viruses: parainfluenza viruses, influenza virus, adenovirus, and respiratory syncytial virus (RSV).

Atypical organisms: Mycoplasma pneumoniae.

Bacterial: Pneumococcus, mycobacterial tuberculosis.

Older children and adolescents:
Atypical organisms: Mycoplasma pneumoniae, Chlamydia trachomatis.

Bacterial: Pneumococcus, B. pertussis, mycobacterial tuberculosis.

Other rare causes of pneumonia:
Histoplasma capsulatum: It is found in nitrate-rich soil from bird droppings and decaying wood. It is usually acquired as a result of the inhalation of spores. The infection is usually asymptomatic; however, in infants and young children, it may cause respiratory distress and hypoxemia.

Cryptococcus neoformans: is a common among pigeon breeders, seen in immunocompromised patients.

In older children, pneumonia may complicate common varicella infections

Presentation

Neonates: Refusal of feeds, lethargy. Tachypnea, grunting, retractions, cyanosis.

Infants: Cough, fever, Refusal of feeds, lethargy. Tachypnea, grunting, retractions, cyanosis, wheezing, noisy breathing.

Preschoolers: cough, post tussive vomiting, fever, chest pain, abdominal pain.In severe cases: Tachypnea, grunting, retractions, cyanosis,

Older Children: fever, cough, chest pain, dyspnea. Pharyngitis and otalgia/otitis are other common symptoms.

The pathognomic sign of pneumonia is the presence of crackles (also called as crepitations). Localized crepitations in a febrile child without underlying lung disease is pneumonia until proven otherwise. However, not all children with pneumonia have crepitations. Decreased breath sounds with a dull note on percussion and the presence of bronchial breathing are also suggestive of pneumonia.

Sequelae

• Most children with uncomplicated pneumonia recover without sequelae. Persistent effusions and empyemas are the most common serious complications of bacterial pneumonia.

• Pulmonary abscess

• Respiratory distress

• Sepsis

• Pneumatoceles especially with staphylococcal infections

In children who have recurrent or chronic symptoms, further testing including skin testing to identify fungal pathogens, sweat chloride estimation to identify Cystic fibrosis, titers against rare organisms, and bronchoscopy may be required.

Prognosis

The prognosis for most forms of pneumonia is excellent.

• Most cases of viral pneumonia resolve without treatment; common bacterial pathogens and atypical organisms respond to antimicrobial therapy.

• The prognosis for varicella pneumonia is somewhat more guarded.

• Staphylococcal pneumonia, although rare, can be very serious despite treatment.

• Immunocompromised children, those with underlying lung disease, and neonates are at high risk for severe sequelae.

• Some forms of viral pneumonia, particularly adenoviral disease, tend to cause bronchiolitis obliterans and hyperlucent lung syndrome.

Diagnosis of Pneumonia

Complete blood count: WBC count is often increased with a polymorphic predominance in bacterial infections. Lymphocytic predominance may be seen in viral pneumonia, pertussis, and atypical infections.

Cultures: In the cooperative older child with a productive cough, a sputum Gram stain is useful. Sputum cultures and immunofluorescent antibody testing may be useful. Bactec cultures (sputum or blood) are useful to isolate the organisms).

Imaging Studies: Chest x-ray PA view is the diagnostic test for pneumonia. Sometimes to differentiate from a sine-pneumonic effusion, a USG chest may be required. In rare cases of children who have an effusion or an empyema identified on CXR, a CT scan may be needed to further define the scope of the problem.

Mantoux Test: To diagnose pneumonia due to mycobacterial tuberculosis.

Cold agglutinin test: A bedside cold agglutinins test may help confirm the clinical suspicion of mycoplasmal infection. This test is performed by placing a small amount of blood in a specimen tube containing anticoagulant and inserting this into a cup filled with ice water. After a few minutes in the cold water, the tube is held up to the light, tilted slightly, and slowly rotated. Small clumps of red blood cells coating the tube are indicative of a positive test result. This test is positive only in about one-half of the cases of mycoplasmal infection and has high chances of false-positive reactions.

Other tests: If there is a presence of pleural fluid, pleural fluid aspiration and culture, and microscopy.

Differentiation Between Bacterial and Viral Pneumonia

Bacterial pneumonia: Usually associated with a fever more than 103 degrees F. It is often a lobar, segmental or rounded well-defined pneumonia affecting a single lobe or multiple lobes. There may associated pleural effusion with abscess, bullae, or pneumatoceles.

Viral pneumonia: The fever is usually lower than 103 degrees F. The pneumonia is poorly defined, interstitial, or peribronchial affecting multiple sites predominantly in multiple sites and poorly defined. There may be subsegmental atelectasis.

Treatment

Oxygen is required if there is grunting, flaring, severe tachypnea, and retractions.

Bacterial Pneumonia: Antibiotics: oral or intravenous

Penicillins:

They are appropriate first-line agents in children in whom the pneumococcal disease is strongly suspected. They have limited activity against gram-negative bacteria due to resistance.

First generation cephalosporins:

They are useful against gram positive organisms and Proteus mirabilis, H influenzae, Escherichia coli, Klebsiella pneumoniae, and Moraxella catarrhalis.

• Cephalexin: 50 mg/kg/day PO bid

• Cefadur: 30-50 mg/kg/day PO bid.

• Cefuroxime: 30 mg/kg/d PO bid, IV: 150-200 mg/kg/d IV divided q8h.

• Cefalothin: 50 mg/kg/day PO qds/100 mg/kg/day IV qds.

Second generation cephalosporin:

They are useful against gram-positive organisms and have limited activity against gram negative organisms.

• Cefaclor: 20-40 mg/kg/day PO tds

Third generation cephalosporins:

They are broad-spectrum antibiotics having good gram-negative activity.

• Cefixime: 8 mg/kg/day PO bid.

• Ceftriaxone: 50-100 mg/kg/d IV/IM bd not to exceed 1 g.

• Cefotaxime: 100-200 mg/kg/d IV/IM divided q6-8h.

• Cefpodoxime: 10 mg/kg/d PO divided bid

• Cefprozil: 30 mg/kg/d PO divided bid

TMP-SMX: 21 mg/kg/day PO/IV for 21 days. Useful for PCP pneumonia.

Macrolides: They are used for treatment of staphylococcal and streptococcal infections. Also used in the treatment of atypical pneumonia due to mycoplasma, chlamydias.

Viral pneumonia

• RSV: Serious infections with this organism usually occur in infants with underlying lung disease. Aerosolized ribavirin can be given to severely affected infants.

• Herpes virus: Acyclovir is available for the treatment of these pneumonia. Dose: 10 mg/kg/dose IV q8h; infuse over 1 h

• Influenza pneumonia, which is particularly severe or when it occurs in a high-risk patient, may be treated with oseltamivir

Children who are toxic:
Antibiotic therapy should include vancomycin (particularly in areas where penicillin-resistant streptococci have been identified) and a cephalosporin.

Prevention

Globally, pneumonia kills nearly 1 million children younger than 5 years of age each year. Although various pathogens may cause pneumonia, either singly or in combination, two bacteria are the leading causes: Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (pneumococcus). Hib and pneumococcus together account for more than 50% of pneumonia deaths among children aged 1 month to 5 years.

Vaccines can help prevent infection by some of the bacteria and viruses that can cause pneumonia. Vaccines are available for the following infections:

• Haemophilus influenzae type b (Hib)

• Influenza (flu)

• Measles

• Pertussis (whooping cough)

• Pneumococcal

• Varicella (chickenpox)

What are the other steps to prevent pneumonia apart from vaccines?

• Hand hygiene: Wash your hands often.

• Stay away from people who have cold, cough, and fever.

• Avoid people with chickenpox and measles if you haven’t got the vaccines against them.

• Avoid smoking and smoking areas.

• Cough etiquette: Cough or sneeze into a tissue or a napkin instead of hands so that your germs do not spread to others.

Which are the vaccines for preventing pneumonia?

Routinely vaccines to prevent H.influenza B (Hib Vaccine), pertussis (DPT vaccine), measles (Measles or MMR vaccine) are given to all children. In addition, the pneumococcal vaccine (PCV13) is now included in the universal immunization program in some states in India and is routinely used in the western world in all children <5 years of age. Flu vaccine and Chickenpox vaccine is recommended in the high-risk group. The immunization schedule of these vaccines is given in table 1.

Table 1: Immunization schedule of vaccines that can prevent pneumonia due to certain infection

PCV- Pneumococcal conjugate vaccine, MMR- Measles, Mumps, Rubella vaccine, Tdap- Tetanus, diphtheria, acellular pertussis vaccine, HiB- HiB vaccine, DPT - Diphtheria, pertussis, tetanus vaccine

How would vaccination help to prevent pneumonia?

World Health Organization (WHO) recommends the inclusion of both Hib and PCV vaccines in routine immunization programs. Together, HibV and PCV, are expected to prevent at least 1,075,000 child deaths each year predominantly in developing countries, and with herd protection additional cases and deaths in older age groups.

Pneumococcal vaccine in children

There are 2 types of pneumococcal vaccines: polysaccharide unconjugated pneumococcal vaccine (PPSV23) and conjugated pneumococcal vaccine (PCV 13 and PCV 10). PCV10 (marketed as Synflorix) contains ten serotypes of pneumococcus (1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F and 23F) which are conjugated to a carrier protein. PCV13 (marketed as Prevenar13) contains thirteen serotypes of pneumococcus (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F). PCV13 is registered in over 150 countries and is part of the National Immunization Program in 115 of them, including India. PCV13 also provides protection against serotypes 3, 6A and 19A which are relevant in Indian context for the disease caused due to them. PCV13 contains serotype 19A and the antimicrobial resistance for serotype 19A is increasing globally.

• For routine immunization both PCV10 and PCV13 are licensed for children from 6 weeks to 5 years of age.

• Primary schedule (for both PCV10 and PCV13): 3 primary doses at 6, 10, and 14 weeks with a booster at age 12 through 15 months.

• Additionally, PCV13 is licensed for the prevention of pneumococcal diseases in adults >50 years of age.

Pneumococcal vaccine in adults

Two pneumococcal vaccines for adults 65 years or older:

• A single dose of the pneumococcal conjugate vaccine (PCV13) is recommended followed by a dose of the pneumococcal polysaccharide vaccine (PPSV23) at least 1 year later.

• If a patient has already received PPSV23, then PCV13 should be given at least 1 year after receipt of the most recent PPSV23 dose.