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7/30/2019 CNS - CLINICAL CORRELATIONS TO THE VARIOUS SYSTEMS 1
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CLINICAL CORRELATIONS TOTHE VARIOUS SYSTEMS 1
A Presentation
By
Ms R.Venkatajothi, MSc., MPhil, PhD
Senior Lecturer
Department of Microbiology
Faculty of MedicineAIMST UNIVERSITY
Central Nervous Tissue
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OBJECTIVES
The objectives of this lecture are to
List the common microbial agents causing CNSinfections.
Discuss the routes of transmission and thepathogenesis of CNS infections.
Describe the microbiology laboratory diagnosis ofagents causing CNS infections.
Describe the principles of prevention of CNS
infections.
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INTRODUCTION
Nervous tissue is organized into two basic systems;
(1) The Central Nervous System (CNS) and(2) The Peripheral Nervous System (PNS).
The central nervous system of humans contains thebrain, spinal cord and retina.
PNS consists of the nerves and ganglia outside of thebrain and spinal cord.
Bacteria, Virus, Fungus and Protozoa can cause
infection in the CNS.
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Infections - CNS Meningitis:-
Meningitis is inflammation of the membranescovering the brain and spinal cord (meninges). It canbe caused by a bacteria, viruses & other microbes.
Encephalitis:-
Inflammation of brain, most often due toinfections. It can be caused by a bacteria, viruses,protozoa & other microbes.
Meningoencephalitis:-
Meningoencephalitis is both meningitis andencephalitis. Pathogens may be bacterial, viral, fungal,
or parasitic.
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COMMON BACTERIAL AGENTS CAUSINGCNS INFECTIONS
GRAM POSITIVE BACTERIA GRAM NEGATIVE BACTERIA
Staphylococcus aureus Neisseria meningitidis
Group B Streptococci Pseudomonas aeruginosa
Streptococcus pneumoniae Haemophilus influenza
Myobacterium tuberculosis Escherichia coli
Listeriasp Citrobactersp
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COMMON PREDISPOSING FACTORCAUSING CNS INFECTIONS
The following common predisposing factors areinvolved. They are;
Immuno-compromised state.
Basilar skull fracture (fracture of the base of the skull).
Head trauma (Head injury).
Post neuro surgery.
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GENERAL LAB DIAGNOSIS FOR BACTERIA
Gram staining.
Loop full of centrifuged Cerebrospinal fluid (CSF)
inoculated onto routine bacterial isolation media.Such as; CSF Blood agar plate
Nutrient agar,
Blood agar, Chocolate agar,
MacConkey agar.
Biochemical tests can be confirm the organism.
Serological diagnosis and Molecular diagnosis.
Antibiotic sensitivit test.
TRAN MI I N AND PATH ENE I F
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TRAN MI I N AND PATH ENE I F
CNS INFECTIONS
TUBERCULOSIS MENINGITIS
Myobacterium tuberculosisinvades the membranesand fluid surrounding the brain and spinal cord.
The infection usually begins elsewhere in the body,usually in the lungs, and then travels through thebloodstream to the meninges where small abscesses
called microtubercles are formed.
When these abscesses burst, TB meningitis is theresult. Following are the common symptoms of TB;
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TUBERCULOSIS MENINGITIS Low grade evening fevers, Night sweats, Weight loss,
Neck stiffness etc.
TB meningitis is most common in children below 4years old age. AFB stain L J media
LAB DIAGNOSIS:-
Acid fast bacilli (AFB)staining method usedfor the identification of
M. tuberculosisbacilli.
Lowenstein Jensen (L J) culture medium is useful forthe identification of bacteria.
TB can be confirm by PCR technique.
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COMMON VIRUSES CAUSING CNS INFECTION
Entero viruses:-
Polio virus.
Coxsackie virus.
Arboviruses:-
Region specific viruses forex;
Murray Valley encephalitisvirus in Australia.
West Nile virus in USA.Family of Herpesviruses:-
Herpes Simplex virus 1 & 2.Varicella Zoster virus.
Cytomegalovirus.
Epstein-Barr virus.
Other viruses:-
Adeno virus, Rhinovirus,
HIV, Influenza virus A & B.Mumps virus, Rabies virus,Japanese B encephalitisvirus etc.
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Lab Diagnostic test for Meningitis : Lumbarpuncture
A lumbar puncture collects cerebrospinal fluid to checkfor the presence of disease or injury.
A spinal needle is inserted, usually between the 3rd and4th lumbar vertebrae in the lower spine.
RABIES
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RABIES The rabies virus infects the CNS. It can transmit
through the saliva of animals (dog). It is causing acute
encephalitis and leads to death.
The virus travels from the wound to the brain, whereit causes swelling or inflammation. This inflammation
leads to symptoms of the disease.GENERAL LAB DIAGNOSIS FOR VIRUSES
Clinical specimen - CSF, Respiratory secretions,skin biopsy etc.
Serology diagnosis - Viral Antigen or antibodydetection (infected tissue), Viral RNA detection(RT-PCR). In Rabies virus, cerebral inclusion bodiescalled Negri bodies can be observed.
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Rabies virus Negri bodiesObserving neuronal brain cells with intra cytoplasmicinclusions (Negri bodies) is a method of diagnosing
Rabies virus
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FUNGUS CNS INFECTION
Cryptococcosis
Cryptococcus neoformansinfections occur worldwideand it is a capsulated fungus.
C. neoformansisolated in soil and large amounts inpigeon droppings. It does not cause disease in birds.
Fungus spread by inhalation. Primary infection inlungs. It can spread to skin, bone and prostate.
Cryptococcalmeningitis is most common clinicalmanifestation and particularly dangerous fungus in
AIDS patients. Other fungus Aspergillussp , Rhizopussp & Candida
sp can also causes CNS infection to human being.
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LABORATORY DIAGNOSIS FOR FUNGUS
Lumbar puncture and microscopic examination ofcerebrospinal fluid (CSF) is used for diagnostic.
C. neoformanscapsule can be observed by usingIndia ink staining (Negative staining) method. In thisstaining method, background of slide is stained whilethe organisms remain clear (bright).
Saline and 10% KOH Wet mount technique and
Sabourauds dextrose agar Culture media is useful forthe identification of fungus.
Observation of Cyrptococcal antigens in CSF and
Serum specimen.
LAB DIAGNOSIS
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LAB DIAGNOSIS
C. neoformans capsule
(India ink staining)
TransmissionofC. neoformans
PREVENTION OF CNS INFECTIONS
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PREVENTION OF CNS INFECTIONSIMMUNOPROPHYLAXIS
Haemophilus influenzae type B vaccine (HiB):-
Administration to two month age of baby.
BCG Vaccine:-
It can Prevents spinal and meningeal TB.
Pneumococcal conjugate vaccine (PCV7):-
Children between the ages of 2 and 5 who are athigh risk of pneumococcal disease, including children
with chronic heart, lung disease or cancer.
h l i i d
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Immunoprophylaxis continued
Pneumococcal polysaccharide
vaccine (PPV):-The Centers for Disease Control and Prevention(CDC) recommends the PPV vaccine for older than
65, younger adults and children with compromisedimmune systems or chronic illnesses such as heartdisease, diabetes etc.
Rabies vaccine:-
Rabies can be prevented by vaccination, both in
humans and other animals.
I h l i ti d
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Immunoprophylaxis continued
Meningococcal conjugate vaccine (MCV4):-The CDC and the American Academy of Pediatrics
recommend this vaccine be routinely administeredfor the following previously unvaccinated groups:children 11-12 years old, youngsters at high schoolentry (about age 15) and college freshmen living indormitories.
Overall, maintain personal and environment hygienic
to prevent some of the CNS infections.
Proper treatment can decrease the effects ofmeningitis and other CNS infections.
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LEARNING OUTCOMES
List the common microbial agents causing CNSinfections.
Discuss the routes of transmission and thepathogenesis of CNS infections.
Describe the microbiology laboratory diagnosis ofagents causing CNS infections.
Describe the principles of prevention of CNSinfections.
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BOOKS FOR REFERENCE
Text book of Microbiology by Ananthanarayanand Panikers.
A Text book of Microbiology by P.Chakraborty.
Medical Microbiology by Jawetz, Melnick, &
Adelberg's.
Medical Microbiology by Murray.
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