The evaluation of Staphylococcus aureus and Staphylococcus epidermidis in hospital air, their antibiotic resistance and sensitivity of S. aureus to cefoxitin.

Staphylococci as a nosocomial infection agent, increases the possibility of contracting diseases such as wound infection, sepsis and skin infections in humans. It was shown that Staphylococcus aureus considered as a commensal organism causing various both endemic and epidemic hospital-acquired infections. Air samples were collected from Sina Hospital, Hamadan city, which dedicated to various respiratory diseases and analysed by biochemical tests. The resistance and sensitivity of bacterial strains to the cefoxitin antibiotic were also determined. Staphylococcus aureus density (CFU/m3) were measured in the air of various wards as follows: infectious 13.35 ± 7.57, poisoning 29.84 ± 33.43, emergency 8.64 ± 2.72, eye operation room 0, recovery room 6.28 ± 4.90, skin outpatient operation room 4.71 ± 2.36, respiratory isolation 0, ICU 0.79 ± 1.36, and the administrative room 6.28 ± 5.93; while the Staphylococcus epidermidis were as follows: infectious 1.57 ± 2.35, poisoning 2.35 ± 4.08, emergency 2.35 ± 2.35, eye operation room 0, recovery room 0.78 ± 1.36, skin outpatient operation room 2.35 ± 2.35, respiratory isolation 0, ICU 2.35 ± 4.08, and the administrative room 1.57 ± 1.36. The positive and negative control samples showed a concentration of 0. Moreover, among the S. aureus isolates, 33.3% were found to be resistant to cefoxitin, while 40.6% showed to be sensitive. Based on the results, the number of active people and the type and quality of ventilation are very effective in the air quality of various wards of hospital. The poisoning section showed the most contaminated air and the highest resistance and sensitivity to the cefoxitin antibiotic.

Evaluation of SARS-CoV-2 in Indoor Air of Sina and Shahid Beheshti Hospitals and Patients' Houses.

Side by side air sampling was conducted using a PTFE filter membrane as dry sampler and an impinger containing a suitable culture medium as a wet sampler. Most of the samples were collected from two hospitals and few air samples were collected from private houses of non-hospitalized confirmed COVID-19 patients. The collected air samples were analyzed using RT-PCR. The results indicated that all air samples collected from the hospitals were PCR negative for SARS-CoV-2. While two of four air samples collected from the house of non-hospitalized patients were PCR positive. In this study, most of the hospitalized patients had oxygen mask and face mask, and hence this may be a reason for our negative results regarding the presence of SARS-CoV-2 in indoor air of the hospitals, while non-hospitalized patients did not wear oxygen and protective face masks in their houses. Moreover, a very high concentration of particles in the size range of droplet nuclei (< 5 µm) was identified compared to particles in the size range of respiratory droplets (> 5-10 µm) in the areas where patients were hospitalized. It can be concluded that using face mask by patients can prevent the release of viruses into the indoor air, even in hospitals with a high density of patients.