HUMAN
INFECTIOUS DISEASE AND DIAGNOSTICS-ANSWER KEY
INTERNAL
EXAMINATION-II (SET A&B)
SECTION-A
1. a) Hackel
2. c)
monocytes
3.
d)Ehrlich
4.
b)Immunogens
5. c)
VR
6.
a) positive anaerobes
7. a)
Gram-negative
8. b)
Pathogenicity
9. c)
attenuation
10. b)
bacteraemia
11. c)
entero
12 a) V.
cholerae
13.a) falciparum
14. c) S. dysentriae
15.
a) Bordetella
SECTION-B
16. How
can you describe the normal flora?
A. Beneficial role: Infection resistance, Nutrient source, Stimulation of immune system
and epithelial turnover: B. Disease production
Anatomical
location of normal flora: Skin, Conjunctival sac, Oral cavity and
Respiratory tract (Oral cavity, upper respiratory tract), Gastrointestinal
tract, Urogenital tract, External auditory meatus
17/22.
AIDS
HIV-Retrovirus – are RNA viruses containing reverse transcriptase (a RNA directed DNA
polymerase) enzyme. They are enveloped viruses with icosahedral symmetry.
The genome consists of 2 copies of ss RNA with RT enzyme. They include 3 genus
– Onco viruses, Lenti viruses and Spuma
viruses.
AIDS; This is the
end stage of the disease. There is irreversible breakdown of the immune system
making the patient susceptible for any common opportunistic infections and
malignancies. Respiratory infections
– symptoms include – dry cough, dysponea, fever.
Ø Gastro – intestinal tract – ginigivitis,
oral thrush, dysphagia, diarrhea, abdominal pain and chronic colitis (gay bowel
syndrome in homo – sexuals).
Ø Central nervous system – lymphoma. Toxoplasmosis, Mtb, Candida, Aspergilus
Ø Cutaneous –dermatitis, impetigo, folliculitis,
Kaposi’s sarcoma. Candida and Herpes.
Ø Paediatric AIDS
12. Typhoid
1. Enteric fever:
·
This is caused by Salmonella typhi or Sallmonella paratyphi A, B, C.
·
The symptoms of Salmonalla typhi are higher than Salmonella paratyphi A, B, C.
·
The onset is gradual with headache, malaise,
loss of appetite, abdominal discomfort
·
Complications-bronchitis, brocho pneumonia,
arthritis, abcesses, nephritis, anemia.
·
The Salmonella
A,B and C also produces enteric fever but it is generally milder.
·
The infection of Salmonella paratyphi C produces
septicemia.
2.Gastro Enteritis and
Food Poisoning:
v The
gastroenteritis- dysentery and diarrhoea accompanied abdominal pain and fever.
v Symptoms-headache,
malaise, nausea, shivering, dehydration, hypotension, cramps 3.Bacterimia:
v bacteria
enters into the bloodstream it is dissimilated to other parts of the body
v Complications-
osteomylitis, meaningitis, abcess formation, hepatomegaly, UTI, bone marrow and
kidney disorders.
13. Whooping cough.
Ø Whooping cough (pertussis) is an
infection of the respiratory systemcaused by the bacterium Bordetella pertussis (or B.
pertussis).
Ø It mainly affects babies younger than
6 months old who aren't yet protected by immunizations, and kids 11 to 18
years old whose immunity has started to fade.
Ø Whooping cough
causes severe coughing spells, which can
sometimes end in a "whooping" sound when the child breathes
in.
Signs & Symptoms: runny nose, sneezing, mild cough, low-grade fever
14. Dysentery.
Dysentery is
an intestinal infection that causes severe diarrhea with blood. In some cases,
mucus may be found in the stool. This usually lasts for 3 to 7 days.
Symptoms may include:
Ø abdominal cramps or pain, nausea,
vomiting, fever of 100.4°F (38°C) or higher, dehydration
v Dysentery is usually spread as a
result of poor hygiene.
Types of dysentery
There are two major types: Bacillary
dysentery and Amebic dysentery, caused respectively by Bacteria and by Amoebas.
15. Small pox.
Etiology :Smallpox results from
infection by variola virus (genus
Orthopoxvirus, family Poxviridae).
SECTION-C
16. Lymphoid organs and types of immunity
Primary
Lymphoid Organs:
(a) Bone marrow (b) Thymus
Secondary
Lymphoid Organs:
(a) Spleen, (b) Lymph nodes, (c) Mucosal
associated Lymphoid Tissue (MALT)
Types
Of Immunity:
There are two major types of
immunity: innate or natural or nonspecific and acquired or adaptive.
(A) Innate
or Natural or Nonspecific Immunity (L. innatus = inborn):
Components
of Acquired Immunity:
Acquired immunity has two components:
humeral immunity or Antibody mediated immune system (AMIS) and cellular
immunity or cell mediated immune system (CMIS).
17. Classification of microorganism
Microbial taxonomy
Taxonomy [Greek taxis, arrangement, and nomos, law, or nemein, to distribute] is defined as
the science of biological classification. In
simple term, taxonomy is orderly arranging organisms under study into groups of
larger units. It
consists of three interrelated parts namely
1.
Classification is
the arrangement of
organisms into
groups or taxa (s., taxon) based on
mutual similarity or evolutionary relatedness.
2.
Nomenclature is
concerned with the assignment
of names to
taxonomic groups in agreement with published rules.
3. Identification is the practical side of taxonomy, the process of determining
that a particular isolate belongs
to a recognized taxon. (So in short Identify-Naming them
and classify them)
18. How
could you explain maximum about collection & transport of clinical sample?
General
instructions
Request Slips
The
request slip clearly fill in the following information.
1) Patients Name, Age, Sex, Hospital number, Date
and time of collection.
2) Source of specimen.
3) Clinical details.
Blood sample
collection, Urine sample collection, Ear, Nose and Eye swabs:
Biopsies, tissue
scrapings etc., Sputum sample collection: Pus aspirated:
CSF sample
collection:Collected sample is
separated in 3 portions.
1st
portion of CSF is used for chemical analysis.
2nd
portion of CSF is used for smear analysis.
3rd
portion is used for cultural analysis.
Stool sample
collection
Serological
specimens
19. Can
you describe in detail about staining Host pathogen interaction?
Virulence factor
Pathogenicity-Pathogenicity
denotes the ability of microorganisms to cause disease.
·
infect
a host and produce as disease is a pathogen.
Virulence-capacity
of a given strain-produce disease. Attenuated - low virulence of a strain.
Virulence
factors-Infectivity, Invasiveness, Toxigenicity
Infectivity:
ability to overcoming, the defensive barriers of the host
Invasiveness
Toxigenicity-exotoxins
(2 subunits.-Fragment B,A), endotoxins (cell wall-gram-negative bacteria).
Enzymes:
virulence factor enhanced [Ex.] Hyaluronidase, Streptokinase, DNase, Coagulase.
Infecting
dose: The minimum infection dose (MID) or minimum lethal dose (MLD)
Route
of infection: eg. Vibrio cholerae is
effective orally.
20. How
could you explain detail about tuberculosis?
General
characters:
They are acid-fast, slender, rod, aerobic, non-motile, non-capsulated and
non-sporing. Growth is generally slow.
Morphology: M. tuberculosis is straight
or slightly curved rod 1 to 4 µ
long and 0.2 to 0.8 µ
·
It
may be arranged singly or in groups. It is non-motile, non-sporing and
noncapsulated.
Culture
Characters:It
is aerobic. It grows slowly (generation time 14 to 15 hours).
·
Colonies
appear in 2 to 6 weeks. Optimum temperature is 37°C and pH is 6.4 to 7.
Pathogenesis: The basis of
virulence of bacillus is unknown. It does not produce toxin. May be the various
components of bacillus possess different biological activities influencing
pathogenesis, allergy and immunity in disease.
Symptoms: Vague and non
specific malaise, anorexia, weight loss, fever, sweats, cough. But many cases
are symptomless.
·
Site of primary
infection: local
lesion with enlargement of lymph nodes.
·
Tuberculous
bronchopneumonia: infection
throughout the lung with discharge
·
Caseation: Production of
thick cheesy material consisting of pus cells and necrotic tissue
·
Miliary
Tuberculosis: Small
tubercles found widely throughout the body
·
Tuberculous
Meningitis: Blood
borne spread of infection which affects the brain
·
Bone and Joint
Tuberculosis: common
form is spinal tuberculosis.
21.
Describe in detail about the Nosocomial infection and malaria.
Hospital
acquired infections are defined as infections developing in patients after
admission to the hospital, which were neither present nor in incubation at the
time of hospitalization
Source of hospital
infection:
« Endogenous origin
« Inanimate objects
« Exogenous origin
« Hospital air
« Surfaces
Mode of
transmission
1.
Contact route g
Direct contact, Indirect contact
2. Air
borne route
3.
Oral route
4.
Parenteral route
Malaria-Inc period – 10
– 14 days (P.falciparum, P.vivax, P.ovale); P.malariae
Prevention:
Reduction
in transmission,
Control
of mosquitoes, Prevent mosquito bite
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