Questions
1. Atypical lymphocytosis is most likely to be found in which of the diseases? ( Mononucleosis induced by EBV)
2. Orchitis, which may cause sterility, is a possible manifestation of which virus?(Mumps)
3.Parvovirus infection causes mild exanthem in children, is characterized by? ( Haemolytic anaemia)
4.Which of the following is transmitted by fecal- oral route, can be acquired from shellfish and often causes acute jaundice, diarrhea, and liver function abnormalities? (Hep A)
5. An experimental compound is discovered that prevents the activation of adenyl cyclase and the resulting increase in cAMP. The toxic effects of which bacteria can be prevented with this compund? ( Vibrio Cholerae)
RTI
Viral infections are treated symptomatically. Streptococcal pharyngitis and epiglottitis caused by H influenzae are treated with antibacterials. Haemophilus influenzae type b vaccine is commercially available and is now a basic component of childhood immunization program.
Management
Symptomatic treatment is used for most viral infections. Bacterial pneumonias are treated with antibacterials. A polysaccharide vaccine against 23 serotypes of Streptococcus pneumoniae is recommended for individuals at high risk.
Pathogenesis
Lower Respiratory Infection
Organisms enter the distal airway by inhalation, aspiration or by hematogenous seeding. The pathogen multiplies in or on the epithelium, causing inflammation, increased mucus secretion, and impaired mucociliary function; other lung functions may also be affected. In severe bronchiolitis, inflammation and necrosis of the epithelium may block small airways leading to airway obstruction.
Upper Respiratory Infection
Organisms gain entry to the respiratory tract by inhalation of droplets and invade the mucosa. Epithelial destruction may ensue, along with redness, edema, hemorrhage and sometimes an exudate.
Investigations
Lower RTI
(b) Pneumonia
Diagnosis:
1. Blood culture
2. Microscopy
3. Acid-fast stains
4. ELISA : Antigen
5. Fluorescent-antibody test
6. Serology
7. PCR
(a) Bronchitis and Bronchiolitis
Diagnosis:
1. Cultures: Sputum, Aspirations of nasopharyngeal secretions or
2. Serology : Antibody
3. Fluorescent-antibody staining
4. ELISA
5. PCR
Upper RTI
(c) Otitis
Diagnosis:
1. Otoscopy
2. Culture: middle ear effusion
(e) Epiglottitis and Laryngotracheitis
Diagnosis:
1. Blood culture
2. Cultures : pharyngeal swabs
3. Serology : To detect a rise in antibody
4. Immunofluorescent-antibody staining (rapid diagnostic technique
5. Enzyme-linked immunosorbent assay (ELISA
6. PCR
(d) Pharyngitis
Diagnosis:
1. Culture
2. Serology
3. Fluorescent antibody (Rapid diagnostic tests)
4. Latex agglutination
5. PCR
(b) Sinusitis
Microbiologic Diagnosis:
1. For acute sinusitis, the diagnosis is made from clinical findings.
2. Bacterial culture: Nasal discharge (Not very helpful as the recovered organisms are generally contaminated by the resident flora from the nasal passage.)
3. In chronic sinusitis, a careful dental examination
4. Sinus x-rays
5. Antral puncture : to obtain sinusal specimens for bacterial culture (specific)
(a) Common Cold
Microbiologic Diagnosis:
1. Symptoms (lack of fever combined with symptoms of localization to the nasopharynx).
Common Pathogens
Lower Respiratory Infection : Bronchitis, Bronchiolitis and Pneumonia
Hantavirus
Measles
VZV
Aspergillus spp.
Cryptococcus neoformans
Histoplasma capsulatum
Chlamydia trachomatis/ psittaci/ pneumoniae
Coxiella burnetii
Mycobacterium tuberculosis
Legionella spp
Pseudomonas aeruginosa
E. coli
Klebsiella pneumoniae
Streptococcus pyogenes
Staphylococcus aureus
Haemophilus influenzae
Upper Respiratory Infections : Common Cold, Sinusitis, Pharyngitis, Epiglottitis and Laryngotracheitis
Virus
HSV
CMV
EBV
Coxsackievirus A
Influenza
RSV
Adenovirus
Parainfluenza virus
Coronavirus
Rhinovirus
Fungus
Candida albicans
Bacteria
Streptococcus pneumoniae
Haemophilus influenzae type b
Mycoplasma pneumoniae
Neiserria Gonorrhea
Corynebacterium Diptheriae
Group A beta hemolytic streptococci
