cns - clinical correlations to the various systems – 1

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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cns - clinical correlations to the various systems – 1

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