Strep pneumoniae
What is Streptococcus Pneumoniae?
Streptococcus pneumoniae (S. pneumoniae) is the most common cause of community-acquired pneumonia (CAP), and also of bacterial pneumonia in children worldwide. With more than 90 known sub-types (serotypes), S. Pneumoniae is a gram-positive bacteria that commonly inhabits the respiratory tract without being pathogenic. It is the predominant cause of pneumonia in the elderly and children but also causes other respiratory infections (e.g., rhinitis, bronchitis, sinusitis) as well as otitis media, meningitis, endocarditis, peritonitis, sepsis, pericarditis, and osteomyelitis, among others. Most S. pneumoniae serotypes can cause disease, but only a few serotypes can cause pneumonia. S. pneumoniae is also known as pneumococcus and any infection caused by the bacterial strain S. pneumoniae is known as pneumococcal disease.
Besides pneumonia, S. pneumoniae is also a common cause of other severe infections:
Meningitis
Ear infections (acute otitis media)
Sinus infections (sinusitis) (e.g., rhinitis, bronchitis, sinusitis)
Bacteremia and, potentially septicemia/sepsis
What is Pneumonia?
Pneumonia is a respiratory infectious disease that affects one or both the lungs--an inflammatory condition that affects the lungs’ alveoli. The alveoli are tiny air sacs in the lungs. In normal conditions, the alveoli fill-up with air during inhalation. In pneumonia, there is fluid and pus build-up in the alveoli that restrict the oxygen intake and result in painful breathing problems and inability to oxygenate (1).
Pneumonia can be caused by bacteria, viruses, or fungi. The most common infectious agents that cause pneumonia are (1):
Streptococcus pneumoniae
Haemophilus influenzae type b (HiB)
Respiratory syncytial virus
According to the Centers for Disease Control (CDC), about 150,000 hospitalizations from pneumococcal pneumonia occur annually in the United States. Pneumococci account for up to 30% of adult community-acquired pneumonia. Bacteremia occurs in up to 25–30% of patients with pneumococcal pneumonia. The mortality rate is 5–7% and may be much higher among elderly patients.
What is Meningitis?
Meningitis is inflammation of the membrane called meninges that acts as a protective covering for the brain and the spinal cord. Meningitis can affect individuals of any age group. Besides S. pneumoniae, meningitis can also be caused by viruses. The condition can have long-term adverse sequellae. If not treated on time, meningitis can be fatal. Although vaccines are available, they do not provide 100% protection. Severe cases of meningitis can progress to septicemia i.e., blood poisoning.
Pneumococci cause more than 50% of all cases of bacterial meningitis in the United States. An estimated 2,000 cases of pneumococcal meningitis occur each year. Some patients with pneumococcal meningitis also have pneumonia. The mortality rate of pneumococcal meningitis is about 8% in children and 22% in adults. In the United States, pneumococci have become the leading cause of bacterial meningitis in children.
What is sinusitis?
Infection of the sinuses (air-filled pockets present in the face) is known as sinusitis. Although most cases of sinusitis are caused by viruses, pneumococci are also known to cause sinus infection.
What is acute otitis media?
Acute otitis media is infection of the middle ear. Pneumococci are a common cause of acute otitis media accounting for about 20% of those infections. Amongst infants (by first 12 months), over 60% have at least one episode of acute otitis media. Middle ear infections are the most frequent cause for pediatric medical visits in the United States with more than 18 million visits annually. It is also the most common reason for children to receive antibiotics. Complications of pneumococcal otitis media may include mastoiditis and meningitis.
What is bacteremia?
Bacteremia refers to presence of bacteria in the bloodstream. An estimated 5,000 cases of pneumococcal bacteremia (without pneumonia) occur each year in the United States. The overall mortality rate for bacteremia is about 20% but may be as high as 60% among elderly patients. Bacteremia can be life-threatening in asplenic patients (absence of spleen).
In children aged 2 years and younger, bacteremia without a known site of infection is the most common invasive clinical presentation of pneumococcal infection accounting for approximately 70% of invasive disease. Bacteremia pneumonia causes about 12–16% of invasive pneumococcal disease among children of this age group.
What are the Risk Factors of S. pneumoniae Infection?
In normal conditions, pneumococci are common inhabitants of the respiratory tract. These bacteria can be isolated from the nasopharynx of 5–90% of healthy persons, depending on the population and country; they are more commonly found in adults with children, as only 5–10% of adults without children are carriers. A high percentage of school-aged children, 20–60%, are carriers of pneumococci. Amongst military personnel, as many as 50–60% may be carriers. The duration of carriage of the bacterial strain varies and is usually longer in children than adults. Pneumococcal disease is not always seen in carriers of the bacteria. The development of the disease is usually related to a weakened immune system. The risk factors of S. pneumoniae infection are as follows:
Age: S. pneumoniae infection can occur in any age group and gender, however, children (< 2 years old) and the elderly (> 65 years old) are at higher risk of contracting infection as they have relatively weaker immune systems than healthy adults
Seasons: winter and early spring
Smoking
Alcohol abuse
Coexisting respiratory conditions like asthma, chronic obstructive pulmonary disorder (COPD)
Asplenia: people without a spleen or a healthy functional spleen.
What are the Signs and Symptoms of S. pneumoniae Infection?
Signs and symptoms of various S. pneumoniae infection are as follows:
Pneumonia
Abrupt onset of fever and chills
Productive cough (sputum)
Shortness of breath
Chest pain
Weakness
Increased heart rate
Rapid and shallow breathing
Meningitis
Fever
Headache
Vomiting
Seizures
Irritability
Lethargy
Coma
Sinusitis
Stuffy nose
Runny nose
Headache
Facial pain
Sore throat
Cough
Mucus dripping down the throat
Bad breath
Acute Otitis Media
Ear pain
Fever
Hearing loss
Drainage of fluid from affected ear
Bacteremia
Fever and chills
Nausea and vomiting
Difficulty in breathing
Rapid heart rate
Lightheaded
Loss of appetite
Loss of consciousness
Who diagnoses and treats S. pneumoniae infection?
Doctors in multiple specialties diagnose and treat S. pneumoniae:
Internal medicine, pediatrics, family medicine, emergency medicine, and ambulatory medicine, for initial presentation.
Pulmonology, as the infection most commonly occurs in the lower respiratory tract
Infectious disease or pediatric infectious disease, for more serious cases
Critical care medicine, for more serious cases
Neurology, for management of meningitis
Otolaryngology, for sinusitis and rhinitis, and otology/neurotology, for otitis media
Pathology, for diagnosis of blood or fluid samples
Radiology, for diagnostic imaging
How is S. pneumoniae infection diagnosed?
In general, a definitive diagnosis of infection with Streptococcus pneumoniae is based on isolation of the microorganism from blood samples or other normally sterile body sites. Tests are also available to detect capsular polysaccharide antigen, which is produced by the S. pneumoniae, and signals its presence.
For adults, a urinary antigen test based on immunochromatographic membrane technique to detect the capsular polysaccharide antigen of Streptococcus pneumoniae is commercially available. The test is rapid and simple to use. It also has a reasonable specificity in adults. The antigen can also detect pneumococcal pneumonia after antibiotic therapy has been started.
What treatments are currently available for S. pneumoniae infection?
Antibiotic therapy remains the mainstay for treating pneumococcal disease. However, effectiveness of treatment varies due to multi-drug resistance.
Treatment for Pneumonia
To treat pneumococcal pneumonia in the outpatient department, the Infectious Diseases Society of America recommends a macrolide, doxycycline, amoxicillin (with or without clavulanic acid), or a quinolone. For inpatient pneumococcal pneumonia treatment, patients are usually administered penicillin (one million units intravenously over 4 hours), ampicillin (1g every 6 hours), or ceftriaxone (1g every 24 hours). Improvement of symptoms can be seen within 48 hours.
Treatment for Meningitis
Pneumococcal meningitis has been treated with 12 to 24 million units of penicillin every 24 hours, 2g ceftriaxone every 12 hours or 2mg cefotaxime every 6 hours. All of these drug regimens are effective against antibiotic-susceptible S. pneumoniae.
Treatment for Otitis Media
In children, amoxicillin 30mg/kg is recommended for treatment of otitis media. For adults, 500 mg tablets of amoxicillin four times a day is recommended. Treatment is recommended for 5 days.
Treatment for Sinusitis
Amoxicillin is the first-line therapy for treatment of sinusitis. In about 80-90% cases, the drug is effective.
Medical Malpractice and S. pneumoniae Infection
Medical malpractice and negligence in patients with S. pneumoniae infection can include the following:
Failure to order the appropriate diagnostic tests
Failure to rule out similar diseases
Misdiagnosis of the condition
Delay in treatment onset leading to serious complications
Errors in diagnostic evaluation (misreading imaging tests, error in laboratory testing)
Negligence in monitoring patient treatment
Errors in drug dosage
Failure to follow-up and monitor the patient’s treatment outcome