Hospital air: A potential route for transmission of infections caused by β-lactam–resistant bacteria

  • Seyed Hamed Mirhoseini
    Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran

    Student Research Center, Isfahan University of Medical Sciences, Isfahan, Iran

    Department of Environmental Health Engineering, School of Health, Arak University of Medical Sciences, Arak, Iran
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  • Mahnaz Nikaeen
    Address correspondence to Mahnaz Nikaeen, PhD, Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Hezar Jerib Ave, Isfahan, Iran 8174673461. (M. Nikaeen).
    Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran
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  • Zahra Shamsizadeh
    Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran

    Student Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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  • Hossein Khanahmad
    Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Published:March 24, 2016DOI:


      • The emergence of β-lactam–resistant bacteria is a major health concern.
      • There was a relatively high prevalence of 3 groups of airborne β-lactam–resistant bacteria in hospitals.
      • Beta-lactamase–encoding genes were detected with various frequencies in isolated β-lactam–resistant bacteria.
      • Staphylococcus and Acinetobacter were detected as the most predominant β-lactam–resistant bacteria.
      • Hospital air may play an important role in the transmission of β-lactam–resistant bacteria.


      The emergence of bacterial resistance to β-lactam antibiotics seriously challenges the treatment of various nosocomial infections. This study was designed to investigate the presence of β-lactam–resistant bacteria (BLRB) in hospital air.


      A total of 64 air samples were collected in 4 hospital wards. Detection of airborne bacteria was carried out using culture plates with and without β-lactams. BLRB isolates were screened for the presence of 5 common β-lactamase–encoding genes. Sequence analysis of predominant BLRB was also performed.


      The prevalence of BLRB ranged between 3% and 34%. Oxacillin-resistant bacteria had the highest prevalence, followed by ceftazidime- and cefazolin-resistant bacteria. The frequency of β-lactamase–encoding genes in isolated BLRB ranged between 0% and 47%, with the highest and lowest detection for OXA-23 and CTX-m-32, respectively. MecA had a relatively high frequency in surgery wards and operating theaters, whereas the frequency of blaTEM was higher in intensive care units and internal medicine wards. OXA-51 was detected in 4 wards. Acinetobacter spp, Acinetobacter baumannii, and Staphylococcus spp were the most predominant BLRB.


      The results revealed that hospital air is a potential route of transmission of BLRB, such as Acinetobacter and Staphylococcus, 2 important causative agents of nosocomial infections. Therefore, improvement of control measures against the spreading of airborne bacteria in hospital environments is warranted.

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