Microbiology 🦠 Flashcards
what is Meningitis?
- inflammation of meninges covering brain and spinal cord
Signs & Symptoms of Meningitis
- Headache
- Photophobia
- Malaise
- Neck stiffness
- Coma
Types of meningitis
- Epidemic cerebrospinal meningitis (bacterial)
- Tuberculous meningitis
- Acute aseptic meningitis
Causative organisms of Epidemic cerebrospinal meningitis (bacterial)
- Neisseria meningitides.
- Streptococcus pyogenes
- Streptococcus pneumoniae
- Staphylococcus aureus
- Haemophilus influenza
- pseudomonas aeruginosa
what are types of Acute aseptic meningitis?
Viral infection:
- Primary: poliomylitis, Coxsackie’s, ECHO and arboviruses.
- Secondary :to mumps, chicken pox, and measles.
Spirochaetal infection:
- Leptospira causing swineherd disease.
Causes of Neonatal meningitis
- E.coli.
- Citrobacter.
- Group B streptococci.
- Klebsiella,Enterobacter.
- Listeriamonocytogenes.
Lab diagnosis of meningitis
- Sample
- Direct film
- PCR
- Serological method
Sample for diagnosis of meningitis
CSF
Collection of CSF
- Lumbar puncture
- Aseptic conditions
- between 4th and 5th lumbar vertebrae.
- screw-capped bottles
- Sent to the laboratory at once
General rule for specimen collection
- Wash your hands before and after sample collection
- Samples must be: Before the start of antimicrobial therapy.
- CSF specimens are best taken at the bedside where suitable media are directly inoculated.
- Viral transport media for transporting swabs for viral cultures.
Significance of PCR in diagnosis of meningitis
PCR is a great diagnostic tool in all types of meningitis.
Serolofical methods in diagnosis of meningitis
- using commercially available bacterial antigen kit to detect the presence of common bacterial pathogens. These tests are considered one of the rapid diagnostic methods.
what does Neisseria meningitides cause?
acute cereprospinal meningitis
Morphology & Characters of Neisseria meningitides
- Gram-negative, kidney shape, diplococci, pilliated & capsulated
- intracellular
Laboratory diagnosis of acute cerebrospinal meningitis.
- Samples
- Direct film
- Culture
- Identification
- Definitive Identification
- Rapid diagnosis
Sample in Diagnosis of a case of N.meningitidis
- CSF, blood and in the nasopharynx early in the disease.
- C.S.F is obtained by lumbar puncture under complete aseptic precautions.
Morphology of CSF in a case of N.meningitidis
- C.S.F is turbid and under tension due to presence of pus cells.
Direct film in Diagnosis of a case of N.meningitidis
- Detection of intracellular Gram Negative diplococci is diagnostic
Culture in Diagnosis of a case of N.meningitidis
PPT
Identifecation in Diagnosis of a case of N.meningitidis
PPT
Difference between Neisseria gonorrhea and Neisseria meningitidis
- Neisseria gonorrhea which causes gonorrhea in man ferment glucose only (not ferment maltose ) with production of acid.
Definitive identification in diagnosis of a case of acute cerebspinal meningitis
- by agglutination with specific meningococcal antisera.
Rapid diagnosis in diagnosis of a case of acute cerebspinal meningitis
- may be obtained by detection of meningococcal antigen in CSF by latex agglutination test .
Diagnosis of carrier of N.meningitidis, and what should The obtained growth be differentiated from?
- Nasopharyngeal swab is examined as in diagnosis of case.
- The obtained growth should be differentiated from commensal neisseria.
Compare between pathogenic & Commensal niesseria in terms of:
- Temperature
- Ordinary media
- Thyer Martin medium
- Colony pig
- Reaction with antimeningococcal sera
PPT
Types of Viral Meningitis
Primary:
- Poliomyelitis, Coxsackie’s and ECHO viruses.
Secondary:
- to Mumps, Chicken pox, and Measles.
CSF in aseptic meningitis
Aseptic meningitis with CSF shows much lymphocytes
Family of Poliovirus
- Picornaviridae, Enterovirus family
Genome of Poliovirus
RNA
where is poliovirus produced and released?
- produced and released into the gut (and throat initially)
From where could we isolate poiliovirus?
can be isolated from the throat or stools for some weeks following the incubation period.
what are 4 different clinicl forms of Poliovirus?
- Abortive Poliomyelitis.
- Non paralytic Poliomyelitis (Aseptic meningitis).
- Paralytic Poliomyelitis.
- Progressive post-poliomyelitis muscle atrophy.
what is Echoviruses short for?
Enteric Cytopathic Human Orphan viruses
Genome of Echoviruses
RNA virus
Family of Echoviruses
Picornaviridae, Enterovirus family
what is Echoviruses considered as a common cause of?
- Common cause of enteric infections.
- Associated with some cases of aseptic meningitis.
Pattern of Coxsackie viruses
- In man, show a seasonal, epidemic pattern of infection (mostly sub- clinical), associated with meningitis, paralysis, and myocarditis.
Laboratory diagnosis of viral infection
- Direct detection
- Indirect (Virus isolation)
- Serologic detection of antiviral antibodies
Direct detection in Laboratory diagnosis of viral infection
- Detection of Virus particles by (electron microscope)
- Detection of viral antigens by (EIA, RIA…) and nucleic acid by (PCR).
Indirect (Virus isolation) in Laboratory diagnosis of viral infection
Viruses are obligate intracellular parasites and can be cultivated on:
A) Tissue cultures: cytopathic effect (CPE)
B) Embryonated egg.
C) Animal inoculation
Serologic detection of antiviral Abs in Laboratory diagnosis of viral infection
By serological methods (EIA, RIA…).
Diagnosis of TB meningitis
PPT
Is MTB acid fast bacilli?
YES
CSF in TB meningitis
C.S.F is less turbid than that in meningococcal meningitis and contains excess of lymphocytes.
Direct film Diagnosis of TB meningitis
(ZN stain) is prepared from the deposit after centrifugation.
Cilture in cases of Diagnosis of TB meningitis
- Deposit is cultured directly on L-J medium or Dorest’s egg medium (without decontamination) .
Lab diagnosis of meningitis In general
PPT
