A child presents with recurrent bouts of severe cough followed by an audible whoop. Which of the following is considered the best type of specimen to isolate the organism and confirm the diagnosis.
**Core Concept**
Pertussis, also known as whooping cough, is a highly contagious bacterial infection caused by *Bordetella pertussis*. The bacterium resides in the nasopharynx and can be transmitted through respiratory droplets. Accurate diagnosis is crucial for implementing appropriate treatment and preventing further transmission.
**Why the Correct Answer is Right**
Nasopharyngeal swabs are the best type of specimen to isolate *Bordetella pertussis* and confirm the diagnosis because they directly sample the respiratory tract where the bacterium primarily resides. This method allows for a higher concentration of the organism, increasing the chances of successful culture and identification. **Option A** is the correct answer because it targets the primary site of infection, making it the most effective specimen type for diagnosis.
**Why Each Wrong Option is Incorrect**
**Option B:** Cough plates are not a standard or reliable method for diagnosing pertussis. They may capture respiratory droplets, but the yield is often low, and the technique is not specific for *Bordetella pertussis*.
**Option C:** Throat swabs are not the best option for diagnosing pertussis because they may not effectively sample the nasopharynx, where the bacterium primarily resides. This can lead to false-negative results or delayed diagnosis.
**Option D:** Anterior nasal swabs may not accurately represent the nasopharynx, where *Bordetella pertussis* resides. This can result in false-negative results or delayed diagnosis, making it a less reliable option for diagnosing pertussis.
**Clinical Pearl / High-Yield Fact**
In cases of suspected pertussis, it's essential to obtain a nasopharyngeal swab as soon as possible, ideally within the first 2-3 weeks of symptoms. This increases the chances of successful culture and identification, allowing for timely implementation of antibiotics and preventing further transmission.
**✓ Correct Answer: A. Nasopharyngeal swab**