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PNEUMOCOCCUS

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mariam kavtaria

on 30 September 2018

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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
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
(chronic cardiorespiratory disease, diabetes, liver disease, alcoholism)
Immunosuppression (eg, HIV)
Functional or anatomic
asplenia
Sickle cell disease
- leads to splenic infarction
Residents of specialized care facilities
Patients with
cochlear implants
CSF leaks
Smokers
Damage of the respiratory epithelium
may predispose to invasion - chronic bronchitis, or influenza virus
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 (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
(up to 50% of patients),
seizures, learning disabilities, mental dysfunction, and nerve palsies.

Pneumococcal endocarditis
may produce a corrosive valvular lesion, with sudden rupture or fenestration, leading to
rapidly progressive heart failure
.
Septic arthritis -
usually

a
complication of bacteremia;
S
imilar to septic arthritis caused by other gram-positive cocci,
Spontaneous pneumococcal peritonitis
- 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.

Quellung test -
staining with India ink causes the
capsule to appear like a halo around the organism


Serotyping and genotyping of isolates -
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 gallolyticus
formerly - S. 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
- 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 sputum).

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 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 -
lobar pneumonia
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)
Elevated liver function tests
Anemia,
Low serum albumin levels
Hyponatremia
Elevated serum creatinine levels

Non-specific Labs:

Pleural effusion

in up to 40% patients
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
(otherwise healthy patient)
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
Meningitis - inflammation of meninges
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
(esp. 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
(
Normal
:
15 to 60 mg/100 mL
)
(3)
Elevated white blood cell
count (
normal: 0 - 5 WBC (all mononuclear and no red blood cells
(4)
reduced glucose
concentration (Normal:
50 to 80 mg/100 mL)
(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
Life threatening condition:
Lumbar Puncture
is done - Sample is sent for testing
Medications are initiated without knowing the exact cause -
broad coverage
Prophylactic antibiotics:
For
functional or anatomic asplenic children
< 5 yr - penicillin
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 19Th 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
Spread is via
airborne droplets

Can also cause:
Encapsulated bacteria
resist phagocytosis
unless antibodies fix complement to its capsule
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