Upper Respiratory Infections and Diphtheria

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Questions and Answers

Who is at the greatest risk for infection?

Children aged 1 to 3 years

Adults aged 18 to 25 years

Children younger than 1 year (correct)

Elderly individuals over 65 years

Which of the following methods is used for laboratory diagnosis?

Clinical history assessment

Microscopy, culture, and PCR (correct)

X-ray imaging

Blood pressure monitoring

What type of antibiotic is commonly used for treatment in this age group?

Penicillin

Tetracycline

Cephalosporin

Macrolide (correct)

Which of the following is NOT included in the methods for laboratory diagnosis?

Ultrasound imaging Signup and view all the answers

What is the primary mechanism of transmission for the organism discussed?

Respiratory droplets Signup and view all the answers

What is a characteristic of children at greatest risk for infection?

They are younger than 1 year Signup and view all the answers

Which factor is considered the most important determinant of virulence for the organism?

Polysaccharide capsule Signup and view all the answers

What type of infections do unencapsulated strains typically cause?

Mucosal infections Signup and view all the answers

What type of strains are referred to as 'untypeable'?

Strains lacking a polysaccharide capsule Signup and view all the answers

Which statement is true about encapsulated strains?

They are associated with invasive infections. Signup and view all the answers

What is the title of the book authored by Bauman, Machunis-Masuoka, and Cosby?

Microbiology: With diseases by body system Signup and view all the answers

Who are the authors of the microbiology book mentioned?

Robert W. Bauman, Elizabeth Machunis-Masuoka, and Cecily D. Cosby Signup and view all the answers

Which publishing company released the mentioned microbiology book?

McGraw-Hill Companies Signup and view all the answers

What is the main focus of the book 'Microbiology: With diseases by body system'?

Microbiology associated with diseases by body system Signup and view all the answers

Which test is NOT categorized as an in vitro test?

Blood pressure measurement Signup and view all the answers

At what age is the first dose of DPT typically administered?

6 weeks Signup and view all the answers

What is the appropriate age for the booster dose of DT?

5–6 years Signup and view all the answers

Corynebacteria resembling C. diphtheriae are referred to as what?

Diphtheroids Signup and view all the answers

Which of the following in vitro tests is primarily used for detecting pathogenic bacteria?

Polymerase chain reaction (PCR) Signup and view all the answers

What effect does pertussis toxin have on ciliated epithelial cells?

Increases mucus production Signup and view all the answers

Which of the following statements about pertussis toxin is correct?

It is involved in excessive mucus production. Signup and view all the answers

What is the duration of the paroxysmal stage of coughing?

2 to 4 weeks Signup and view all the answers

How does pertussis toxin primarily affect the respiratory system?

By increasing mucus secretion in the respiratory tract Signup and view all the answers

What characterizes the cough during the paroxysmal stage?

Coughing spells of three or four coughs without a breath Signup and view all the answers

What is the average incubation period mentioned?

7-10 days Signup and view all the answers

What type of cells are primarily affected by pertussis toxin?

Ciliated epithelial cells Signup and view all the answers

What stage follows the paroxysmal stage?

Convalescent stage Signup and view all the answers

What is a potential consequence of pertussis toxin's action on epithelial cells?

Excessive mucus buildup Signup and view all the answers

How many coughs typically occur in a spell during the paroxysmal stage?

Three to four coughs Signup and view all the answers

Study Notes

Upper Respiratory Tract Infections

Upper respiratory tract infections include pharyngitis, croup, and epiglottitis. A key pathogen in these infections is Haemophilus influenzae.

Corynebacterium Diphtheriae

Corynebacterium diphtheriae is a gram-positive bacillus with an irregular shape, sometimes appearing clubbed at one or both ends.
It's highly pleomorphic, showing varied shapes resembling Chinese letters or cuneiform patterns.
Useful media include Loeffler's serum slope tellurite blood agar.
Sugar fermentations are typically done in Hiss's serum peptone water.
C. diphtheriae is H2S positive and reduces nitrate to nitrite.
Toxigenic strains produce a potent exotoxin.
Toxogenicity depends on the presence of corynephages (tox+).
Diphtheria toxin is a heat-labile protein with two fragments. It inhibits protein synthesis.
Clinical forms include respiratory and cutaneous.
Microscopy, culture, and virulence tests are used for diagnosis, with in vivo and in vitro methods for virulence testing.
Diphtheria presents as a sore throat, localized pain, fever, pharyngitis, and oozing fluid.
The fluid thickens to form a thick pseudomembrane.
The pseudomembrane adheres tightly to the tonsils, uvula, roof of mouth, pharynx, and larynx, potentially causing bleeding and airway obstruction. Severe cases can lead to suffocation.
In vivo tests include subcutaneous and intracutaneous tests.
In vitro tests include precipitation tests, tissue culture, ELISA, and PCR.
Prophylaxis involves DPT vaccinations; doses at 6, 10, 14 weeks with boosters at 5-6 years.

Diphtheroids

Some Corynebacterium species resemble C. diphtheriae and are called diphtheroids. These are normal commensals in the throat and skin.
Common diphtheroids include C. Pseudodiphtheriticum and C. xerosis.

Bordetella Pertussis

Bordetella pertussis is a minute, gram-negative, non-acid-fast, non-spore-forming coccobacillus.
Important species include B. pertussis, B. parapertussis, and B. bronchiseptica.
Bordetella pertussis is extremely small, ovoid, gram-negative coccobacilli, exhibiting pleomorphism, and is nonmotile and nonsporing.
Key factors include filamentous hemagglutinin and pertussis toxin. This bacterium also produces several toxins (Pertussis toxin, Adenylate cyclase toxin, Dermonecrotic toxin, and Tracheal cytotoxin).
The pertussis toxin interferes with ciliated epithelial cells, increasing mucus production.
Adenylate cyclase toxin promotes mucus production and inhibits leukocyte function.
Dermonecrotic toxin causes localized constriction and hemorrhage.
Tracheal cytotoxin inhibits cilia movement.
Patients have three stages: catarrhal, paroxysmal, and convalescent. Younger children are most at risk.
Diagnosis includes microscopy, culture, and PCR.
Treatment involves macrolides like erythromycin or azithromycin. Erythromycin is used for prophylaxis.
Vaccination with whole-cell vaccines or acellular vaccines is effective. Whole cell vaccines have more side effects compared to acellular vaccines.
Incubation period is 6-20 days, with an average of 7-10 days.

Haemophilus influenzae

Haemophilus influenzae is a small gram-negative coccobacillus requiring factors X (hemin) and V (NAD) for growth.
Type b causes the majority of invasive disease (around 95%). The capsule is polyribitol phosphate.
The bacterium lives in the upper respiratory tract and is spread by respiratory droplets.
The capsule is the most critical virulence determinant. Non-capsulated strains cause mucosal infections but not invasive infections, and IgA protease is produced.
Common diseases include sinusitis, otitis media, and pneumonia; however, epiglottitis is an uncommon but important complication. The vaccine has largely reduced the incidence of meningitis associated with this bacterium.

Epiglottitis

Epiglottitis is inflammation of the epiglottis.
Symptoms include rapidly worsening sore throat, pain on swallowing, and difficulty swallowing.
Haemophilus influenzae type B is the most frequent cause. Vaccines have dramatically reduced its occurrence.
Severe cases present with airway obstruction and are an urgent medical emergency.
Other pathogens include H. influenzae types other than B, S. pneumoniae, S. pyogenes, and S. aureus.

Vaccination and Treatment

Vaccination schedules vary across organisms and diseases.
Treatment options depend on the specific pathogen.

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Description

This quiz covers upper respiratory tract infections such as pharyngitis and croup, alongside a focus on Corynebacterium diphtheriae, its characteristics, and the diagnostic methods involved. Explore the microbes, their pathogenicity, and the clinical implications of infections. Test your knowledge on this important area of microbiology.