Transmission of respiratory viruses is a complex process involving emission, deposition in the airways, and infection. Inhalation is often the most relevant transmission mode in indoor environments. For severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the risk of inhalation transmission is not yet fully understood. Here, we used an indoor aerosol model combined with a regional inhaled deposited dose model to examine the indoor transport of aerosols from an infected person with novel coronavirus disease (COVID-19) to a susceptible person and assess the potential inhaled dose rate of particles. Two scenarios with different ventilation rates were compared, as well as adult female versus male recipients. Assuming a source strength of 10 viruses/s, in a tightly closed room with poor ventilation (0.5 h−1), the respiratory tract deposited dose rate was 140–350 and 100–260 inhaled viruses/hour for males and females; respectively. With ventilation at 3 h−1 the dose rate was only 30–90 viruses/hour. Correcting for the half-life of SARS-CoV-2 in air, these numbers are reduced by a factor of 1.2–2.2 for poorly ventilated rooms and 1.1–1.4 for well-ventilated rooms. Combined with future determinations of virus emission rates, the size distribution of aerosols containing the virus, and the infectious dose, these results could play an important role in understanding the full picture of potential inhalation transmission in indoor environments.

Coagulase-positive staphylococcus (CoPS), including methicillin-resistant Staphylococcus aureus (MRSA), poses a global threat. The increasing prevalence of MRSA in Saudi Arabia emphasizes the need for effective management. This study explores the prevalence of virulence-associated genes and antibiotic resistance patterns in CoPS. Nasal swabs from 200 individuals were collected, and standard protocols were used for the isolation, identification, and characterization of CoPS and coagulase-negative staphylococci (CoNS). Additionally, antimicrobial susceptibility testing and PCR were conducted. Bacterial growth was observed in 58.5% of participants, with 12% positive for CoPS and 30% positive for CoNS. Hospital personnel carriers showed a significantly higher proportion of CoNS compared with non-hospital personnel carriers. Non-hospital personnel CoPS strains displayed higher sensitivity to oxacillin than hospital personnel strains. Cefoxitin exhibited the highest sensitivity among β-lactam antibiotics. All isolates were sensitive to trimethoprim/sulfamethoxazole, rifampin, and quinupristin. Polymerase chain reaction analysis detected methicillin resistance genes in both non-hospital and hospital personnel MRSA strains. The coa and spa genes were prevalent in MRSA isolates, while the Luk-PV gene was not detected. A high prevalence of CoPS and CoNS was observed in both non-hospital and hospital personnel carriers. Occupational risk factors may contribute to the differences in the strain distribution. Varying antibiotic susceptibility patterns indicate the effectiveness of oxacillin and cefoxitin. Urgent management strategies are needed due to methicillin resistance. Further research is necessary to explore additional virulence-associated genes and develop comprehensive approaches for CoPS infection prevention and treatment in Saudi Arabia.

Background The coagulase-positive staphylococcus (CoPS) has become progressively prevailing in both community and hospital. The variation between community and hospital acquired methicillin resistant coagulase positive staphylococcus has been used to monitor decisions about realistic therapy. Methods Participants presenting with culture proven coagulase positive staphylococcus from the nose were enclosed during this study. Antibiotic susceptibility test was verified by exploiting the E-test and disk diffusion methods. Eleven toxin genes had been analyzed using a polymerase chain reaction. Results The oxacillin-resistant E-test showed extremely vital resistance in hospital-isolates (34.5%) than in community-isolates (19.2%) (p-value = 0.009). The most effective antibiotic against community acquired CoPS is a quinupristin followed by vancomycin and rifampin then clindamycin. Whereas, clindamycin, sulfamethoxazole/trimethoprim, rifampin, and quinupristin seem to be more effective against hospital acquired CoPS. The intermediate effects of both cefoxitin and vancomycin were highly significant in hospital acquired CoPS isolates compared with hospital acquired CoPS isolates (p-value = 0.009 and 0.005). The proven methicillin resistance coagulase positive staphylococcus (MRCoPS) was subjected for detection the following toxin embp (480 bp), aap (180 bp, 200 bp, 300 bp, 460 bp, and 480 bp), and aae (110 bp) genes that were present only in a community acquired MRCoPS. But the following coa (400 bp and 800 bp), spa (1100 bp and 1120 bp), aae (220 bp), and IcaD (100 bp) genes were present only in a hospital acquired MRCoPS. The PVL gene was absent in both community and hospital acquired MRCoPS isolates. Conclusion Hospital acquired coagulase positive staphylococci were highly significant resistant effects against oxacillin and intermediate effects against cefoxitin compared to community acquired coagulase positive staphylococci. All coagulase positive staphylococcus isolates were sensitive to sulfamethoxazole/trimethoprim and quinupristin, but they were resistant to penicillin only. Genotypically, all tested toxin genes showed variation between community and hospital depending on the gene size bands. This study stresses the vital would like for broad screening, precautionary, and educational methods to accomplish the cumulative MRSA prevalence rate.