Pneumococcal pneumonia

As the name suggests, pneumococcal pneumonia is pneumonia caused by bacteria of the genus pneumococcus.

Pneumonia and pleural effusions

Types

There are many types of pneumococcal disease.

• Streptococcus pneumoniae (S. pneumoniae) are lancet-shaped, gram-positive, facultative anaerobic bacteria with over 90 known serotypes. Most S. pneumoniae serotypes can cause disease, but only a minority of serotypes produce the majority of pneumococcal infections.

Habitat

• Pneumococci are common inhabitants of the respiratory tract and may be isolated from the nasopharynx of 5–90% of healthy persons, depending on the population and setting. Only 5–10% of adults without children are carriers. Among school-aged children, 20–60% may be carriers. On military installations, as many as 50–60% of service personnel may be carriers. The duration of carriage varies and is generally longer in children than adults. In addition, researchers do not clearly understand the relationship of carriage to the development of natural immunity.

Transmission

• Transmission of Streptococcus pneumoniae occurs as a result of direct person-to-person contact via respiratory droplets and by autoinoculation in persons carrying the bacteria in their upper respiratory tract. The pneumococcal serotypes most often responsible for causing infection are those most frequently found in carriers.

• Factors such as crowding, season, and the presence of upper respiratory infections or pneumococcal disease, such as pneumonia or otitis media, influence the spread of the organism within a family or household. Although carriage does not necessarily lead to disease, it is an important precursor for pneumococcal disease.

Temporal Pattern

• Pneumococcal infections are more common during the winter and in early spring when respiratory diseases are more prevalent.

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Pneumococcus

Communicability

• The period of communicability for pneumococcal disease is unknown, but presumably transmission can occur as long as the organism appears in respiratory secretions.

Symptoms and complications depend on the part of the body that is infected.

• Pneumonia
• chest x-ray

Pneumococcal pneumonia is the most common clinical presentation of pneumococcal disease among adults. Pneumonia without bacteremia or empyema is not considered to be “invasive” disease. The incubation period of pneumococcal pneumonia is short, about 1 to 3 days. Symptoms generally include an abrupt onset of fever and chills or rigors. Typically, there is a single rigor, and repeated shaking chills are uncommon. Other common symptoms include

• Pleuritic chest pain
• Cough productive of mucopurulent
• Rusty sputum
• Dyspnea
• Tachypnea or tachycardia
• Hypoxia
• Malaise or weakness
• Nausea, vomiting, and headaches occur less frequently.

Complications

• Doctors consider some pneumococcal infections to be “invasive.” Invasive disease means that germs invade parts of the body that are normally free from germs.

• Most pneumococcal infections are mild. However, some can be deadly or result in long-term problems, such as brain damage or hearing loss.

• Meningitis is the most severe type of invasive pneumococcal disease. Of children younger than 5 years old who get pneumococcal meningitis, about 1 out of 15 dies of the infection. The chance of death from pneumococcal meningitis is higher among elderly patients. Others may have long-term problems, such as hearing loss or developmental delay.

CT chest in pneumonia with abscesses caverns and effusions

• Bacteremia is a type of invasive pneumococcal disease that infects the blood. About 1 out of 100 children younger than 5 years old with this bloodstream infection die of it. The chance of death from pneumococcal bacteremia is higher among elderly patients.

Pneumococcal polysaccharide vaccine

• Pneumonia is an infection of the lungs that can cause mild to severe illness in people of all ages. Complications of pneumococcal pneumonia include

• Infection of the space between membranes that surround the lungs and chest cavity (empyema)
• Inflammation of the sac surrounding the heart (pericarditis)
• Blockage of the airway that allows air into the lungs (endobronchial obstruction), with collapse within the lungs (atelectasis) and collection of pus (abscess) in the lungs
• About 5 out of 100 people with non-invasive pneumococcal pneumonia will die from it, but that rate may be higher among elderly patients. Doctors consider pneumococcal pneumonia non-invasive if there’s not bacteremia or empyema occurring at the same time.

• Sinus and ear infections are usually mild and are more common than the more severe forms of pneumococcal disease. However, some children develop repeated ear infections and may need ear tubes.

Risk Factors

• woman using an inhaler

Conditions that increase the risk of invasive pneumococcal disease among adults include:

• Decreased immune function from disease or drugs
• Functional or anatomic asplenia
• Chronic heart, lung (including asthma), liver, or renal disease
• Cigarette smoking
• Cerebrospinal fluid leak or cochlear implant
• Children with functional or anatomic asplenia, particularly those with sickle cell disease, and children with HIV infection are at very high risk for invasive disease. Some studies report rates more than 50 times higher than those among children of the same age without these conditions.

• Children of certain racial and ethnic groups, in particular Alaska Natives, African American, and certain American Indian groups also have increased rates of disease. CDC does not know the reason for this increased risk by race and ethnicity with certainty but it was also noted for invasive Haemophilus influenzae infection (which is also caused by an encapsulated bacterium).

• Research shows that attendance at a childcare center increases the risk of invasive pneumococcal disease and acute otitis media 2–3-fold among children younger than 59 months old.

Diagnosis

• A definitive diagnosis of infection with Streptococcus pneumoniae generally relies on isolation of the organism from blood or other normally sterile body sites. Tests are also available to detect capsular polysaccharide antigen in body fluids.

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Aspiration pneumonia

• A urinary antigen test based on immunochromatographic membrane technique to detect the C-polysaccharide antigen of Streptococcus pneumoniae as a cause of community-acquired pneumonia among adults is commercially available. The test is rapid and simple to use, has a reasonable specificity in adults, and has the ability to detect pneumococcal pneumonia after antibiotic therapy has been started.

• Available data show that pneumococcal bacteria are resistant to one or more antibiotics in 30% of cases.

Medical Management

• Available data pdf icon[5.24 MB, 114 pages] demonstrate that in severe S. pneumoniae cases, the bacteria are fully resistant to one or more clinically relevant antibiotics.

• Following the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in 2000, antibiotic resistance initially declined before increasing again. Then, in 2008, the Clinical and Laboratory Standards Institute (CLSI) changed the definition of penicillin resistance so that a much larger proportion of pneumococci are now considered susceptible to penicillin. The revised susceptibility breakpoints for Streptococcus pneumoniae were the result of a reevaluation that showed clinical response to penicillin was being preserved in clinical studies of pneumococcal infection, despite reduced susceptibility response in vitro.

Vaccine

• CDC recommends pneumococcal vaccination for all infants, young children, and older adults. CDC also recommends clinicians vaccinate older children and adults who are at increased risk for pneumococcal disease.

Chemoprophylaxis

• In general, CDC does not recommend chemoprophylaxis for close contacts of patients with pneumococcal disease. Secondary cases of invasive pneumococcal infection are uncommon.

• The American Academy of Pediatrics typically recommends daily antimicrobial prophylaxis with oral penicillin V or G for children with functional or anatomic asplenia, especially those with sickle-cell disease. In general, clinicians should consider antimicrobial prophylaxis (in addition to immunization) for all children with asplenia younger than 5 years of age and for at least 1 year after splenectomy.

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