Diagnosing Antibiotic-Resistant Infections

To diagnose an antibiotic-resistant infection, your NYU Langone doctor takes a medical history and asks about any medications you are taking. He or she performs a physical examination to look for any signs of skin infections, which may be present in people with a methicillin-resistant Staphylococcus aureus, or MRSA, infection.

In addition, our doctors use several tools to determine the cause of the infection and the best treatment for it. 

Blood Test

A doctor may order a blood test to look for the presence of bacteria, such as MRSA. A rapid test can detect an organism in as little as two hours. The blood can also be tested to determine whether the genetic material in the pathogen is from MRSA or a less dangerous form of Staphylococcus aureus bacteria. 

Bacterial Culture

Your doctor may send a sample of fluid or tissue to a lab for testing. He or she may extract pus from a wound, for instance, or obtain a blood or urine sample. 

Tissue samples are taken from the part of the body where the infection is located. To obtain a specimen from a wound, a doctor rubs a swab over the surface. A urine sample can help the doctor to identify a urinary tract infection. A sample of sputum—a liquid that comes up from your lungs when you cough—can help to diagnose pneumonia.

Your doctor may request a blood test to detect sepsis, a potentially life-threatening complication of an infection. 

Specialists in a laboratory expose the bacteria in the sample to different antibiotics. If the bacteria continue to grow, they are thought to be resistant to the medications. If they are destroyed, they are susceptible to the antibiotics, and your doctor can then prescribe one or more medications to manage the infection.