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PNEUMOCOCCUS

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mariam kavtaria

on 2 April 2017

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Transcript of PNEUMOCOCCUS

PNEUMOCOCCUS
Streptococcus pneumoniae
gram-positive,
α-hemolytic,
aerobic
encapsulated diplococci
commonly colonizes human respiratory tract in winter and early spring
Spread is via airborne droplets.
The
pneumococcal capsule
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:
With the
chronic illnesses
(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
CSF leaks
Smokers
Damage of the respiratory epithelium by chronic bronchitis, or influenza, may predispose to invasion.

Most Common Cause of:
• Otitis media in Children
• Pneumonia
• Meningitis
• Sinusitis
Otitis commonly recurs.
Complications include:
Mild hearing loss,
Balance dysfunction,
Tympanic membrane perforation,
Mastoiditis
Petrositis
Labyrinthitis
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.

Pneumococcal endocarditis
may produce a corrosive valvular lesion, with sudden rupture or fenestration, leading to rapidly progressive heart failure.
Septic arthritis,
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
Catalase
catalase
Staphylococcus
STREPTOCOCCUS
Alfa (Partial)
hemolysis
Beta (Complete hemolysis)
Gamma
(NO Hemolsis)
bacitracin sensitive
bacitracin resistant
Group A
S. Pyogenes
Group B
S. Agalactiae
optochin sensitive
capsulated
Bile soluble
optochin resistant
No capsule
bile insoluble
S. Pneumoniae
Viridans Streptococci
group D
grows in bile
grows in 6.5% NaCl
Enterococcus Faecalis
Non - enterococcus
Grows in bile
No growth in 6.5 %NaCl
Streptococcus Bovis
• Endocarditis
• 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
pNeumonia
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)
Tachycardia (>90bpm)
Dullness to percussion in areas of the chest with significant consolidation
Crackles on auscultation
CLINICAL SIGNS
DIAGNOSIS:
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
Anemia,
Low serum albumin levels
Hyponatremia
Elevated serum creatinine levels

Non-specific Labs:

Pleural effusion - in up to 40% patients, but most effusions resolve during treatment;
<5% patients develop empyema
PNEUMONIA - COMPLICATIONS
Empyema
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
1.

OUTPATIENT
Macrolide or doxycycline (Healthy)
Fluoroquinolone/ beta lactam + Macrolide (comorbidities)

2.
INPATIENT
IV Fluoroquinolone (levofloxacin, Moxifloxacin)
IV beta Lactam (Ceftriaxone) + Macrolide (Azithromycin)
SINUSITIS
Maxillary and ethmoid sinuses are affected Most commonly
MENINGTIS
The most common bacterial causes of meningitis in both adults and children:
S. pneumoniae
Neisseria meningitidis
severe headache
Fever, and nausea
Stiff neck
Photophobia
Seizures
Cranial nerve palsies (particularly of the 3rd and 6th cranial nerves).

CLINICAL FEATURES:
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:
deafness
hydrocephalus
mental retardation in children
The mortality rate for pneumococcal meningitis is 20%.

TREATMENT
1st Line Therapy:
Vancomycin
Ceftriaxone
Medications are given First
Lumbar Puncture is done next
Prophylactic antibiotics:
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.
PREVENTION
2 types of vaccine
Polysacharide Vaccine (PPSV23)
Conjugate Vaccine (PCV13)
contains protein that activates T cells
high levels of memory cell production
Age 19-64
Age > 65
PPSV23 alone
chronic heart disorders
lung/liver disease
diabetes
current smokers
alcoholics
PPSV23 + PPV13
CSF leaks
Cochlear Implants
Sickle cell disease
Asplenia
Immunocompromised (HIV)
Chronic kidney disease
1 dose PCV13 followed by PPSV23 later
UNCOMMON CONDITIONS
Diagnosis
References:
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
Full transcript