Abstract

We as clinicians have been treating fever for decades and yet our approach to diagnosis and management of enteric fever remains flawed. With summer setting in and the monsoons approaching, we will see more and more cases of enteric fever, hence the need to sharpen our diagnostic and therapeutic skills.

The Patient is Vaccinated so it cannot be Typhoid

Nothing can be further away from the truth. Remember that the vaccine gives protection only for three years. So even if the patient claims he has been immunized, ask for the vaccine records. Also the vaccine is only 70% effective at the best hence the child may still get enteric fever inspite of being vaccinated. Furthermore, all the new vaccines cover only typhoid and offer no protection against paratyphoid.

Use of the Widal Test and Use of the Blood Culture

The widal test is a highly overrated, nonspecific and insensitive way of diagnosing enteric fever. You need to demonstrate a four-fold rising titre in paired serum specimens several days apart. Furthermore it is useless in the first week of fever when it is needed the most. In direct contrast, the blood culture (including clot culture and bactec) is an ideal test for suspected enteric fever. With yields as high as 90% in the first week, it remains the gold standard. However keep the following in mind. Ask for the culture in the first week as the yield drops dramatically afterwards. Do submit the specimen before starting any empiric antibiotic treatment. Also use the bactec whenever possible since it clearly increases the yield. Though the initial cost may seem prohibitive [500-1000 rupees], it is definitely cost-effective in terms of avoiding other unnecessary investigations once diagnosis is clinched, avoiding cost of empiric treatment and avoiding cost of hospitalization and treatment of complications in case treatment is delayed due to delayed diagnosis.

Analyzing The Sensitivity Report

Asking for a blood culture not only clinches the diagnosis for us but also makes our choice of antibiotics extremely straightforward. This is very important since enteric fever typically takes several days to respond even if our choice of antibiotics is correct and the culture gives us the confidence to continue the same medication even if response is delayed. Look for and ask for nalidixic acid sensitivity in the culture report as it is a surrogate marker for sensitivity to quinolones. Therefore if the culture report shows resistance to nalidixic acid but sensitivity to ciprofloxacin and ofloxacin, do not use them or if you must use them, use really high doses or the patient may just not respond! Thus, while managing enteric fever, do not ask for the widal test but surely ask for the blood culture, look at the sensitivity report carefully and exercise caution while using quinolones.

Honorary Associate Consultant Paediatrician, Department of Paediatrics, Bombay Hospital, Mumbai.