Most usual causative organism of pharyngitis is-

RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Microbiology

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

Beta-hemolytic streptococci, specifically Group A Streptococcus (GAS) or Streptococcus pyogenes, is the most frequent bacterial cause of acute pharyngitis.
While viruses cause the majority of sore throats, GAS is the most clinically significant bacterial cause, accounting for 15-30% of cases in school-aged children.
This bacterium is transmitted through respiratory droplets from an infected person.
Prompt identification and antibiotic treatment are essential to prevent suppurative complications (like peritonsillar abscess) and non-suppurative complications (like acute rheumatic fever).

Option A: Pneumococci (Streptococcus pneumoniae) are a leading cause of pneumonia, meningitis, sinusitis, and otitis media, but their role in causing pharyngitis is not well-established.
Option C: Escherichia coli (E. coli) is a gram-negative bacterium that is a normal inhabitant of the human intestine. It does not cause respiratory or pharyngeal infections.
Option D: Clostridium is a genus of anaerobic, spore-forming bacteria. Different species cause distinct and severe diseases like tetanus, botulism, and gas gangrene, none of which include pharyngitis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of bacterial pharyngitis as background academic context rather than a clinical decision trigger.
Accurate and timely diagnosis of streptococcal pharyngitis is a critical nursing responsibility to enable prompt antibiotic therapy, which prevents serious complications like acute rheumatic fever and subsequent rheumatic heart disease.
Nurses are often responsible for collecting throat swabs for rapid antigen detection tests (RADT) or throat cultures, which are the gold standards for diagnosing Group A Strep.
Patient education is a key nursing intervention. The nurse must emphasize the importance of completing the full 10-day course of prescribed antibiotics, even if symptoms improve, to fully eradicate the bacteria.

How to Approach the Question

First, identify the keywords in the question: 'most usual causative organism' and 'pharyngitis'. This is a factual recall question about microbiology.
Recognize that the options are all bacteria. The question is asking for the most common bacterial cause of a sore throat.
Systematically review the options and recall the primary diseases associated with each pathogen.
Beta-hemolytic streptococci are famously known as the cause of 'strep throat', a common form of bacterial pharyngitis.
Eliminate the other options based on their primary disease associations: Pneumococci (pneumonia, meningitis), E. coli (UTI, gastroenteritis), and Clostridium (tetanus, botulism).
Confirm that Beta-hemolytic streptococci is the best fit for the 'most usual' bacterial cause of pharyngitis among the choices.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 pp. 343-345, 344-346

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1713-1715