(CBS Philly/CBS Local) — A new study from a University of Pennsylvania professor reveals that stethoscopes are loaded with bacteria, including ones that can cause health care-associated infections.

The study was conducted by Dr. Ronald Collman, a professor of medicine, pulmonary, allergy and critical care at the University of Pennsylvania.

“This study underscores the importance of adhering to rigorous infection control procedures, including fully adhering to CDC-recommended decontamination procedures between patients, or using single-patient-use stethoscopes kept in each patient’s room,” said Collman.

Researchers analyzed 40 stethoscopes that were being used in the ICU and found that all of them were contaminated with a diverse group of bacteria. Staphylococcus, the bacteria known for producing staph infections, was heavily found on all stethoscopes.

But, it could not be determined if the stethoscopes ever made the patients ill.

The effectiveness of the cleaning methods were also reviewed.

Researchers found while the cleaning methods reduced the amount of bacteria they failed to consistently bring contamination to the level of clean, new stethoscopes.

The study was published in the journal Infection Control & Hospital Epidemiology, the Journal of Society for Healthcare Epidemiology of America.