Shigellosis is best diagnosed by –
**Core Concept**
Shigellosis is an infectious disease caused by the bacterium Shigella, leading to a range of gastrointestinal symptoms including diarrhea, abdominal pain, and bloody stools. The diagnosis of shigellosis relies on a combination of clinical presentation, laboratory tests, and sometimes, isolation of the pathogen.
**Why the Correct Answer is Right**
The most effective method for diagnosing shigellosis is through the isolation of Shigella from stool samples, typically using a culture technique. This allows for the identification of the specific serogroup and antimicrobial resistance patterns of the isolate. The stool culture can be performed using selective media such as MacConkey agar or Salmonella-Shigella agar, which favor the growth of Gram-negative bacteria like Shigella.
**Why Each Wrong Option is Incorrect**
**Option A:** Blood tests such as complete blood counts (CBC) or blood cultures are not specific for diagnosing shigellosis and are not the primary method for diagnosing this condition.
**Option B:** Endoscopy may be used to visualize the gastrointestinal tract and obtain biopsy samples, but it is not the most effective method for diagnosing shigellosis.
**Option C:** Polymerase chain reaction (PCR) is a sensitive method for detecting Shigella DNA in stool samples, but it is not the gold standard for diagnosing shigellosis.
**Clinical Pearl / High-Yield Fact**
In cases of suspected shigellosis, it is essential to obtain stool samples for culture and antibiotic susceptibility testing to guide appropriate antimicrobial therapy and prevent spread of the infection.
**Correct Answer: C. Polymerase chain reaction (PCR) is a sensitive method for detecting Shigella DNA in stool samples, but it is not the gold standard for diagnosing shigellosis.