PNEUMOCOCCAL INFECTIONS

PNEMOCOCCAL INFECTIONS 

Edited by, SOWNDHARYA

Pneumococcal infections are caused by streptococcus pneumoniae, a gram positive, catalase-negative organism commonly referred to as Pneumococcus. Streptococcus pneumoniae is the most common cause of community-acquired pneumonia, bacterial meningitis, bacteremia, otitis media, sinusitis, septic arthritis, osteomyelitis, peritonitis and endocarditis. Complications of each of these diagnoses are common. Clinical signs and symptoms and physical examination findings alone cannot distinguish streptococcus pneumoniae disease from infections caused by other pathogens.

EPIDEMIOLOGY:

• High risk age groups (children younger than 5 years, particularly aged 2 years or younger; adults older than 55-65 years)

• Immunocompromised patients(e.g., HIV, Malignancy, diabetes mellitus)

• Conditions associated with decreased pulmonary clearance functions(e.g., asthma, chronic bronchitis, or chronic obstructive pulmonary diseases)

• Presentation from late fall to early spring

CONDITIONS THAT MAY DEVELOP BY DIRECT EXTENSION OF STREPTOCOCCUS PNEUMONIAE FROM THE NASOPHARYNX INCLUDE THE FOLLOWING:

• Conjunctivitis

• Otitis media

• Sinusitis

• Acute exacerbations of chronic bronchitis

• Pneumonia which may be complicated by purulent pericarditis

CONDITIONS THAT MAY RESULT FROM VASCULAR INVASION AND HEMATOGENOUS SPREAD OF S PNEUMONIAE INCLUDE THE FOLLOWING:

• Meningitis

• Bacteremia

• Osteomyelitis and septic arthritis

• Soft tissue infections (e.g., myositis, periorbital cellulitis, abscess)

• Peritonitis

• Cardiac infections(e.g., endocarditis)

DIAGNOSIS:

If a pneumococcal infection is suspected or considered, gram stain and culture of appropriate specimens should be obtained, when possible. Potential specimens may include 1 or more of the following:

• Blood

• Cerebrospinal fluid

• Sputum

• Pleural fluid or lung aspirate

• Joint fluid

• Bone

• Other abscess or tissue specimens

All S pneumoniae, isolates should be tested for susceptibility to penicillin and cefotaxime or ceftriaxone.

Non specific laboratory tests that may support the diagnosis include the following:

• Complete blood count and differential

• Erythrocyte sedimentation rate (ESR)

• C-reactive protein (CRP)

Imaging studies that may be helpful include the following:

• Chest radiography

• Ultrasonography of the chest

• Computed tomography (CT) of the chest, sinuses, face, or affected bones or joints.

• Magnetic resonance imaging (MRI) of the brain (in meningitis) or affected bones and joints 

OTHER MODALITIES THAT MAY HELP DEFINE THE EXTENT OF INFECTION INCLUDE THE FOLLOWING:

• Echocardiography

• Middle ear fluid aspiration

• Pleural fluid aspiration

• Chest tube thoracostomy or catheter placement

• Video assisted thoracoscopy or pleural decortication

• Lumbar puncture

• Joint fluid aspiration

• Biopsy of bone, soft tissue, or muscle

MANAGEMENT:

Antibiotics are the mainstay of therapy. Treatments for specific infections may include the following:

• Otitis media: Amoxicillin 80-90 mg/kg/day; if there is no improvement within 48 to 72 hours, amoxicillin-clavulanate or a second or third generation oral cephalosporin can be initiated.

• Sinusitis: Initial recommendations as for otitis media. In adult penicillin allergic patients and patients who do not respond to initial therapy, switching to fluoroquinolones may be considered. This is not approved for children in this clinical situation.

• Pneumonia: For penicillin sensitive streptococcus pneumoniae (MIC<2 μg/mL), penicillin G or Amoxicillin is considered first-line therapy. For penicillin resistant Streptococcus pneumoniae infection (MIC≥2 μg/mL),the choice of antimicrobial agent should be directed by susceptibility testing.

• Meningitis: In children, a beta lactam (penicillin, ceftriaxone or Cefotaxime) with or without vancomycin pending susceptibility testing can be initiated. Children with hypersensitivity to beta-lactams should receive vancomycin plus rifampin. For adults with penicillin sensitive S pneumoniae infection(MIC ≤0.06 μg/mL), intravenous penicillin G or ampicillin is first line therapy. For penicillin resistant pneumococcus(MIC≥0.12μg/mL), treatment with a third generation cephalosporin or a third generation cephalosporin plus vancomycin is recommended.

ADDITIONAL TREATMENT MEASURES THAT MAY BE HELPFUL FOR PARTICULAR CONDITIONS ARE AS FOLLOWS:

• Complicated pneumonia: Chest tube placement for drainage of pleural fluid. In more severe cases VATS or decortication is recommended

• Suspected septic arthritis or osteomyelitis: The collection of appropriate specimens for gram stain, cell count, histology or culture is recommended and then the antimicrobial therapy can be initiated after susceptibility studies.

• Recurrent or chronic otitis media, periorbital or orbital cellulitis, or facial cellulitis: Surgical intervention is recommended.

MEASURES FOR PREVENTING PNEUMOCOCCAL INFECTION INCLUDE THE FOLLOWING:

• Behavior modification and risk factor reduction is the first and foremost measure to prevent pneumococcal infection

• Medical therapy

• Antimicrobial prophylaxis can be initiated in selected patients with recurrent otitis media

• Immunization: Pneumococcal conjugate vaccine or PCV13 or pneumococcal polysaccharide vaccine or PPSV23 are approved for immunization