Q: Does a standard blood test check for Mycoplasma? My 26-month-old had a fever for 6 days.
Updated: Sep 7
Medically reviewed by Sang Hyun Ahn, MD
Content edited by Myeongchan Kim, MD
This post is a dramatization of a question and answer session experienced by our actual medical reviewers. Please note that this content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
Question:
My 26-month-old baby had a high fever for six days, and their temperature has only just returned to normal. During those six days, we had two blood tests done. The doctor said the inflammation and white blood cell counts were normal, so we didn't do a chest X-ray. Do I need to request a Mycoplasma test separately when getting a blood test, or is it automatically included?
Right now, my baby's temperature is normal, and they are barely coughing. We were prescribed antibiotics and cold medicine. Fever reducers didn't work well; IV fluids helped temporarily, but the high fever would return the next day. If it were Mycoplasma, would the coughing be non-stop and severe? My baby has extremely sticky mucus—like thick, dried glue—which is causing a phlegmy cough.
We plan to visit the clinic again after finishing the medication. Should I ask for a chest X-ray this time? The doctor previously mentioned their lungs sounded clear through the stethoscope.
Also, my baby is currently taking a Cefpodoxime dry syrup antibiotic. Is it normal to prescribe antibiotics even when the inflammation marker is zero?
Answer:
I am very glad to hear that your 26-month-old is recovering after six days of a high fever. I completely understand how worried you must have been during that time. Here is some information regarding your concerns:
Checking for Mycoplasma via Blood Test
Mycoplasma cannot be detected through a standard general blood test (CBC). You need to specifically request a Mycoplasma antibody test. However, please keep in mind that this test can show a negative result during the early stages of the infection, so a re-test is sometimes necessary 1 to 2 weeks later for an accurate diagnosis.
Evaluating the Current Situation
Since your child's fever has broken and the cough has mostly subsided, it appears they are well on the path to recovery. Mycoplasma typically presents with a dry cough that lasts for 2 to 3 weeks (though not necessarily a "non-stop, crazy" cough), and the cough usually persists even after the fever drops. Your baby's thick, sticky mucus and phlegmy cough are actually much more characteristic of a standard cold.
Regarding the Antibiotics
Cefpodoxime is a broad-spectrum antibiotic. Even if blood inflammation markers are at zero, a doctor may prescribe antibiotics based on clinical symptoms if a bacterial infection is suspected. A high fever lasting for six consecutive days strongly suggests the possibility of a bacterial infection. It is highly important that you finish the entire prescribed course of antibiotics to prevent antibiotic resistance and ensure the infection is fully cleared.
For Your Next Clinic Visit
A chest X-ray is typically recommended if the cough worsens or if the fever returns. Since your baby is currently improving and the doctor heard clear lungs, continuing to observe them without an X-ray is a reasonable approach. A Mycoplasma test would generally only be considered if the cough persists for more than two weeks.
As long as your child continues to improve, you can finish the prescribed medication and simply monitor their progress. However, if the fever returns, the cough becomes severe, or if you notice any difficulty breathing, please seek an in-person evaluation with your pediatrician immediately.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
