title: Alteration of Bacterial Antibiotic Sensitivity After Short-Term Exposure to Diagnostic Ultrasound.
abstract: BACKGROUND
  Many pathogenic bacteria show different levels of antibiotic resistance. Furthermore, a lot of hospital-acquired infections are caused by highly resistant or multidrug-resistant Gram-negative bacteria. According to WHO, patients with drug-resistant infections have higher morbidity and mortality. Moreover, patients infected with bacteria that are resistant to antibiotics considerably consume more healthcare resources.
  
  
  OBJECTIVE
  In this study, we explored a physical method of converting drug-resistant bacteria to drug-sensitive ones.
  
  
  METHODS
  This is an in vitro case-control study, performed at the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences (SUMS), Shiraz, Iran in 2014. All experiments were carried out using Gram-negative bacteria Klebsiella pneumonia and E. coli and Gram-positive Staphylococcus aureus and Streptococcus group A, isolated from hospitalized patients. The bacterial strains were obtained from the Persian Type Culture Collection, IROST, Iran (Klebsiella pneumonia PTCC 1290) and Bacteriology Department of Shahid Faghihi Teaching Hospital, Shiraz, Iran (E. coli, Staphylococcus aureus, and Streptococcus group A). The bacteria in culture plates were exposed to diagnostic ultrasound using a MyLab70XVG sonography system for 5 minutes. Then, the bacteria were cultured on Mueller-Hinton agar and incubated at 35°C for 18 hours. Finally, antibiotic susceptibility test was performed and the inhibition zone in both control and exposed groups were measured. Three replicate agar plates were used for each test and the inhibition zones of the plates were recorded.
  
  
  RESULTS
  Compared with the results obtained from unexposed bacteria, statistically significant variations of sensitivity to antibiotics were found in some strains after short-term exposure. In particular, we found major differences (making antibiotic-resistant bacteria susceptible or vice versa) in the diameters of inhibition zones in exposed and non-exposed samples of Klebsiella pneumonia and Streptococcus.
  
  
  CONCLUSIONS
  This study clearly shows that short-term exposure of microorganisms to diagnostic ultrasonic waves can significantly alter their sensitivity to antibiotics. We believe that this physical method of making the antibiotic-resistant population susceptible can open new horizons in antibiotic therapy of a broad range of diseases, including tuberculosis.
authors.affiliation: Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran; Department of Radiology, Faculty of ParaMedicine, Hormozgan University of Medical Sciences, Bandar Abbas, IR Iran.
authors.forename: Seyed Mohammad Javad
authors.initials: SM
authors.lastname: Mortazavi
authors.affiliation: Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Leili
authors.initials: L
authors.lastname: Darvish
authors.affiliation: Department of Radiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abounajmi
authors.affiliation: Department of Microbiology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, IR Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Zarei
authors.affiliation: Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Zare
authors.affiliation: Department of Microbiology, School of Medicine, Kerman University of Medical Sciences, Kerman, IR Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taheri
authors.affiliation: Department of Biostatistics, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Samaneh
authors.initials: S
authors.lastname: Nematollahi
keywords: Antibiotics; Drug Resistance; Infection; Ultrasound