Medical Archive

Introduction

Microbiology

Respiratory droplets are very infective using Pilus called filamentous hemagglutinin

Epidemiology

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Pathogenesis

• 3 virulence
  • Pertussis toxin
    • Ribosylation of Gi (disabling) ? ?cAMP ? ?insulin production, lymphocyte and neutrophil dysfunction, ?sensitivity to histamine
  • Adenylate cyclase toxin
    • Like edema factor, ?cAMP
  • Tracheal toxin
    • Damages ciliated cells in the epithelium

Immunity

Whole-cell vaccine

The duration of immunity after whole-cell pertussis vaccination is short-lived, with little protection remaining after 10–12 years

Acellular vaccine using purified antigens

Studies have demonstrated early waning of immunity—i.e., within 2–4 years after the fifth dose of acellular pertussis vaccine in children who received acellular pertussis vaccine for their primary series in infancy.

Clinical manifestations

Catarrhal stage	1-2??
Spasmodic stage	3-8??
Convalescent stage	9-12??	URI ? ??? ?? ??

• Catarrhal stage (1-2??)
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• Spasmodic stage (3-8??)
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  • ?????? ??? ???? ?? ????, ?? ?? ??? ???? ??? ??? ??? ???? ??.
  • ?????
• Convalescent stage (9-12??)
  • ??? ??? ?? ? ??? ?? ??.
  • URI? ??? ?? ??.

?? ?? ? 3?? ??. ??? ??? 5??.

	Adolescents and adults (%)		Children (%)
Feature	Laboratory Confirmation	No Laboratory Confirmation
Cough	95–100	95–100	95–100
Prolonged	60–80	60–80	60–95
Paroxysmal	60–90	50–90	80–95
Sleep-disturbing	50–80	50–80	90–100
Whoop	10–40	5–30	40–80
Post-tussive vomiting	20–50	5–30	80–90

?? ???

• Vaccine booster? ?? ?? ?? ???? ???? ?.
• Paroxysmal cough > 2weeks
• Posttussive emesis is frequently absent in adults.
• Inspiratory whoop after a severe coughing episode.
• Denudation of respiratory epithelium occasionally leads to hemoptysis after coughing spells.
• CXR is unremarkable in most cases
• Lymphocytosis (toxin-induced)

Complications

• Secondary infection
  • ??? ?? ?? ?? ???.
  • ??? ??, bronchiectasis
• Increased intrathoracic/intraabdominal pressure
  • Scleral hemorrhage, epistaxis, abdominal hernias, pneumothorax
• Erythromycin
  • ???? ????? HPS? ?? ??.

Diagnosis

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Culture of nasopharyngeal secretions remains the gold standard of diagnosis, although PCR has replaced culture in many laboratories because of increased sensitivity and quicker results.

PCR methodology must include primers to diwerentiate among B. pertussis, B. parapertussis, and B. holmesii.

Nasopharyngeal cultures in untreated pertussis remain positive for a mean of 3 weeks axer the onset of illness; these cultures become negative within 5 days of the institution of appropriate antimicrobial therapy.

Differential diagnosis

Treatment

Drug	Adult Daily Dose	Frequency	Duration, Days	Comments
Erythromycin estolate	1–2 g	3 divided doses	7–14	Frequent gastrointestinal side ewects
Clarithromycin	500 mg	2 divided doses	7	—
Azithromycin	500 mg on day 1250 mg subsequently	1 daily dose	5	—
Trimethoprim- sulfamethoxazole	160 mg of trimethoprim, 800 mg of sulfamethoxazole	2 divided doses	14	For patients allergic to macrolides; data on ewectiveness limited

??, ?? ?? Erythromycin
Spasmodic stage ??? ?? ??!

Postexposure prophylaxis

Indications

• Regardless of vaccination history.
• Close contact (eg, household members, direct contact with secretions) with symptomatic patient within the last 21 days.
• High-risk patients, even with limited exposure (eg, pregnant, infant, immunodeficient)

Treatment

• Age <1 month: azithromycin
• Age ?1 month: azithromycin, clarithromycin, or erythromycin.

Immunization