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Transcript of PNEUMOCOCCUS
commonly colonizes human respiratory tract in winter and early spring
Spread is via airborne droplets.
consists of polysaccharide that determines
Serologic type (Serotype)
contributes to virulence and pathogenicity.
> 90 different serotypes have been identified
Most serious infections are caused by serotypes 4, 6, 9, 14, 18, 19, and 23.
These cause about 90% of infections in children and 60% in adults
Patients susceptible to serious pneumococcal infections are:
(eg, chronic cardiorespiratory disease, diabetes, liver disease, alcoholism)
Immunosuppression (eg, HIV)
Functional or anatomic asplenia
Sickle cell disease
Residents of care facilities
Patients with cochlear implants
Damage of the respiratory epithelium by chronic bronchitis, or influenza, may predispose to invasion.
Most Common Cause of:
• Otitis media in Children
Otitis commonly recurs.
Mild hearing loss,
Tympanic membrane perforation,
After universal immunization of infants in the US beginning in 2000, nonvaccine serotypes of S. pneumoniae (particularly serotype 19A) have become the most common pneumococcal cause of acute otitis media.
May be primary or secondary to bacteremia, direct ivasion from infection of the ear, mastoid process, or paranasal sinuses
Complications include hearing loss (in up to 50% of patients), seizures, learning disabilities, mental dysfunction, and palsies.
may produce a corrosive valvular lesion, with sudden rupture or fenestration, leading to rapidly progressive heart failure.
similar to septic arthritis caused by other gram-positive cocci, is usually a complication of bacteremia from another site
Spontaneous pneumococcal peritonitis
occurs most often in patients with cirrhosis and ascites
Pneumococcal bacteremia -
Splenectomy patients are at particular risk.
Mortality rate for bacteremia is 15 to 20% in children and adults
30 to 40% in the elderly
The risk of death is highest during the first 72 h.
Gram stain and culture
Pneumococci are identified by their typical appearance as lancet-shaped diplococci.
Capsule can be detected using the
Quellung test -
staining with India ink causes the capsule to appear like a halo around the organism.
Serotyping and genotyping of isolates can be helpful for epidemiologic reasons (eg, to follow the spread of specific clones and antimicrobial resistance patterns).
Gram Positive Cocci
Beta (Complete hemolysis)
grows in bile
grows in 6.5% NaCl
Non - enterococcus
Grows in bile
No growth in 6.5 %NaCl
• Septic arthritis
• Peritonitis (rare)
Diseases Caused by Pneumococci
Population at Risk:
This process Mainly takes place in the spleen
Acute Otitis Media
Caused by pneumococci in about 30 to 40% of cases.
1/3 of children develop acute pneumococcal otitis media during the first 2 years of life
Abrupt onset of cough and dyspnea accompanied by fever, shaking chills, and myalgias.
The cough evolves from dry to productive purulent sputum and is sometimes tinged with blood (rusty).
Patients may describe stabbing chest pain and significant dyspnea indicating involvement of the parietal pleura
Tachypnea (>30 breaths/min)
Dullness to percussion in areas of the chest with significant consolidation
Crackles on auscultation
The gold standard for etiologic diagnosis is pathologic examination of lung tissue - Biopsy and culture
Best Initial Test - chest radiography
Most cases are diagnosed by Gram's stain and culture of sputum.
Elevated polymorphonuclear leukocyte count (>15,000/L)
leukopenia in <10% of cases (a poor prognostic sign associated with a fatal outcome)
Elevated liver function tests
Low serum albumin levels
Elevated serum creatinine levels
Pleural effusion - in up to 40% patients, but most effusions resolve during treatment;
<5% patients develop empyema
PNEUMONIA - COMPLICATIONS
Fluid in the pleural space plus fever and leukocytosis after 4–5 days of antibiotic treatment Empyema
Pleural fluid with frank pus, bacteria, pH of ≤7.1
Management: Chest tube insertion - Aggressive and complete drainage.
TREATMENT OF PNEUMONIA
Macrolide or doxycycline (Healthy)
Fluoroquinolone/ beta lactam + Macrolide (comorbidities)
IV Fluoroquinolone (levofloxacin, Moxifloxacin)
IV beta Lactam (Ceftriaxone) + Macrolide (Azithromycin)
Maxillary and ethmoid sinuses are affected Most commonly
The most common bacterial causes of meningitis in both adults and children:
Fever, and nausea
Cranial nerve palsies (particularly of the 3rd and 6th cranial nerves).
Confusion, Altered consciousness
Increased intracranial pressure
Kernig's or Brudzinski's sign
MENINGITIS - DIAGNOSIS
Examination of CSF for:
(1) evidence of turbidity (visual inspection);
(2) elevated protein level,
(3) elevated white blood cell count
(4) reduced glucose concentration
(5) identification of the etiologic agent (culture, Gram's staining, antigen testing, or PCR).
A blood culture positive for S. pneumoniae in conjunction with clinical symptoms of meningitis is also considered confirmatory.
Up to 50% of survivors experience complications:
mental retardation in children
The mortality rate for pneumococcal meningitis is 20%.
1st Line Therapy:
Medications are given First
Lumbar Puncture is done next
For functional or anatomic asplenic children < 5 yr, penicillin is recommended.
Penicillin is recommended for older children or adolescents for at least 1 yr after splenectomy.
2 types of vaccine
Polysacharide Vaccine (PPSV23)
Conjugate Vaccine (PCV13)
contains protein that activates T cells
high levels of memory cell production
Age > 65
chronic heart disorders
PPSV23 + PPV13
Sickle cell disease
Chronic kidney disease
1 dose PCV13 followed by PPSV23 later
1. Harrison's Principles of Internal Medicine 18Th edition
2. Merck Manual of Diagnosis and Therapy 19Th edition
3. First Aid For The USMLE Step1 - year 2014 edition
4. Master The Boards USMLE step 2 ck