Pneumococcal infections
Pneumococcal infections are caused by the bacterium Streptococcus pneumoniae, which is a significant pathogen responsible for various diseases, including bacterial pneumonia. This bacillus is particularly dangerous for young children under two years old and adults over sixty-five. Individuals with weakened immune systems, respiratory conditions, and certain ethnic groups, including some Native American populations and African Americans, are also at higher risk. The infection can manifest in different ways, leading to pneumonia, meningitis, bacteremia, middle-ear infections, and sinusitis, with symptoms varying by age and type of infection. Diagnosis typically involves laboratory tests, including Gram's stain and chest X-rays. While penicillin antibiotics are commonly used for treatment, antibiotic resistance poses challenges in managing these infections. Vaccination serves as the primary prevention method, with two types of vaccines available that effectively protect against the most common strains of the bacterium. Understanding pneumococcal infections is crucial for recognizing their impact on vulnerable populations and the importance of vaccination.
Pneumococcal infections
- ANATOMY OR SYSTEM AFFECTED: Lungs, respiratory system
- ALSO KNOWN AS: Pneumococcal disease, Streptococcus pneumoniae infection
Definition
Pneumococcal infection is caused by the encapsulated, gram-positive bacterium Streptococcus pneumoniae, also known as pneumococcus. The term “pneumococcus” was first used in the 1880s to describe this type of infection because pneumococcus was considered the most common cause of bacterial pneumonia.
Causes
Pneumococcal disease is caused by an infection of the bacterium S. pneumoniae.
Risk Factors
Children younger than age two years are at greatest risk of pneumococcal disease. The next most commonly affected are adults age sixty-five years and older. Conditions that cause deficits in the immune system (such as human immunodeficiency virus infection, malignancy, and absence of the spleen) or conditions associated with decreased lung function (such as asthma, chronic bronchitis, and cigarette smoking) are associated with increased risk of pneumococcal disease. Absence of breastfeeding, daycare attendance, and lack of vaccination can also increase the risk of disease. Alaska Natives, Indigenous peoples such as the Navajo and Apache, and African Americans are more commonly affected than other ethnic groups.
Symptoms
Pneumococci bacteria can attack different parts of the body. When the bacteria attack the lungs, they cause pneumonia. When the bacteria invade the bloodstream, they cause bacteremia. Infection of the covering of the brain causes meningitis. Pneumococci may also cause middle-ear infection (otitis media) and sinusitis.
In adults, symptoms of pneumonia include chills, fever, shortness of breath or rapid breathing, chest pain that is worsened by breathing deeply, and a productive cough. Symptoms of meningitis include stiff neck, fever, mental confusion, and photophobia (visual sensitivity to light). Symptoms of bacteremia can include some of the symptoms of pneumonia and meningitis.
In children, symptoms of pneumonia include fever, cough, rapid breathing, and grunting. The symptoms of meningitis vary with age, but include diarrhea, vomiting, and fever. In older children, meningitis symptoms include headache, sensitivity to light, and a stiff neck. Bacteremia typically causes nonspecific symptoms, such as fever and irritability. Otitis media typically causes a painful ear and also may cause sleeplessness, fever, and irritability.
Screening and Diagnosis
If pneumococcal disease is suspected, Gram’s stain and cultures are performed. Chest X-rays are done if pneumonia is suspected. Additional tests include a complete blood cell count, erythrocyte sedimentation rate, and C-reactive protein.
Treatment and Therapy
Penicillin antibiotics are used to treat pneumococcal disease. However, pneumococcal strains have emerged that are resistant to these antibiotics. These resistant forms of pneumococcus are difficult to treat. Broad-spectrum antibiotics may be prescribed to better treat the condition depending on the type of infection present. Common types of antibiotics include Penicillin G or ampicillin, third-generation cephalosporin, and vancomycin. Severe infections may require hospitalization, particularly among high-risk groups.
Prevention and Outcomes
Vaccination is the best prevention strategy. There are two types of pneumococcal vaccine available: a polysaccharide vaccine (PPSV23) and a conjugate vaccine (PCV13). The pneumococcal polysaccharide vaccine protects against the twenty-three types of S. pneumoniae that are responsible for more than 90 percent of all cases of pneumococcal disease in adults. In children, the pneumococcal conjugate vaccine protects against 86 percent of the bacteria types that cause blood infections and 83 percent of those that cause meningitis. However, non-vaccine serotype pneumococcal strains emerged in the early and mid-2020s. To combat this trend, experts investigated the development of new vaccines that targeted pneumococcal strains not covered in early twenty-first-century vaccines.
Millions of individuals are impacted by pneumococcal infections each year. In the United States, around 150,000 people are hospitalized annually, and of those, between 5 and 7 percent die from the infection, most of whom are over sixty-five.
Bibliography
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French, Neil. “Pneumococcal Diseases.” Manson’s Tropical Diseases. 24th ed., Saunders/Elsevier, 2024, pp. 953-67.
Hoffman-Roberts, Holly L., et al. “Investigational New Drugs for the Treatment of Resistant Pneumococcal Infections.” Expert Opinion on Investigational Drugs, vol. 14, no. 8, 2005, pp. 973–95, doi.org/10.1517/13543784.14.8.973. Accessed 18 Dec. 2024.
"Pneumococcal Disease." Cleveland Clinic, 27 Aug. 2022, my.clevelandclinic.org/health/diseases/24231-pneumococcal-disease. Accessed 18 Dec. 2024.
"Pneumococcal Disease." National Foundation for Infectious Diseases, www.nfid.org/infectious-disease/pneumococcal. Accessed 18 Dec. 2024.
Surhone, L. M., et al., editors. Pneumococcal Infection. 2nd ed., Mueller, 2015.