Corona smear is not always reliable
Christine Albert studied German linguistics and literature as well as Scandinavian studies at the Albert Ludwigs University in Freiburg. She is currently doing a traineeship at Hubert Burda Media and is writing, among other things, for
More about the experts All content is checked by medical journalists.An infection with the Sars-CoV-2 coronavirus cannot always be detected via a throat swab. If there is any suspicion, further tests must then follow.
This common form of testing can be negative even with a corona infection, report doctors from the Freiburg University Medical Center in the "Deutsche Medizinische Wochenschrift" (DMW). This is shown by an infected person from Freiburg, where three throat swabs were negative. The experts therefore recommend the analysis of further samples from the stool or from deep respiratory secretions if the usual smear repeatedly turns out negative despite reasonable suspicion.
Corona infection detected via respiratory secretions
According to the information, the special case is about a 46-year-old patient who came to the Freiburg University Clinic with a cough and fever. The symptoms had persisted for a week at this point. After the three negative throat swabs, the doctors finally found the virus genes in coughed up respiratory secretions, the so-called sputum.
At this point in time the patient was already without symptoms. Although he had several risk factors with obesity, high blood pressure, high blood lipid levels and high blood sugar, he survived the infection without major complications.
The swab from the mouth, nose or throat is common practice to prove a corona infection. In the meantime, however, there are increasing indications that this method is not always reliable, said the physician Daniel Hornuss from the Freiburg University Hospital. If laboratory values and the findings in the computed tomography indicate Covid-19, the genetic test should therefore be tried on other biomaterials such as sputum, deep respiratory secretions or stool, advise Hornuss and his colleagues.
Sars-CoV-2 multiplies at the beginning of the infection, especially in the nasopharynx. Therefore, a smear is taken there that can detect the virus. In the further course, the virus density there quickly decreases again significantly. (approx / dpa)
