The potential for community exposures to pathogens from an urban dairy.

The objectives of the study described in this article were to evaluate the variation and transport of fungal and bacterial concentrations in the air of a northern Mexico dairy cattle confined animal feeding operation (CAFO) and to determine the concentration and incidence of antibiotic-resistant Staphylococcus aureus isolates. Two-stage viable cascade impactors were used to measure the culturable airborne fungal organisms and bacteria. S. aureus resistant to penicillin, ampicillin, or cefaclor was identified. Samples were collected at three locations that were designated as on site, upwind of the cattle, and downwind of the cattle. The highest concentrations of culturable bacterial bioaerosols were consistently recovered from the on-site location. More than half of the organisms were antibiotic resistant at the on-site location. Elevated levels of culturable bacterial bioaerosols were recovered from the upwind site that may have been associated with the surrounding community. Bioaerosol concentrations were found in higher amounts than in a facility in the southwestern U.S. examined in the authors' previous study. The urban setting of the CAFO resulted in a higher potential for immediate community exposures.

Seasonal changes in airborne fungi and bacteria at a dairy cattle concentrated animal feeding operation in the southwest United States.

The objective of this study was to evaluate a dairy located in the arid southwest United States to determine the concentrations and seasonal variation of airborne fungi and bacteria and to determine the percentage of antibiotic resistant Staphylococcus aureus. The authors used two-stage ambient air sampling systems to measure the culturable airborne fungal organisms and bacteria on a monthly basis. The authors recovered the most fungal, bacterial, and S. aureus organisms during the spring months. The most common fungi identified were Cladosporium, Aspergillus, and Stemphylium, which were most common in the spring and least common in the summer. S. aureus made up 4.2% to 5.5% of the total bacteria, and greater than 50% of this bacteria were found to be resistant to ampicillin, penicillin, or cefaclor, with the greatest incidence of antibiotic resistance occuring in the fall. The incidence of S. aureus resistant to at least two antibiotics ranged from 14% in the spring to 54% in the fall.

Isolation of Staphylococcus aureus and antibiotic-resistant Staphylococcus aureus from residential indoor bioaerosols.

OBJECTIVE: In this study we evaluated the levels of Staphylococcus aureus and antibiotic-resistant S. aureus in colony-forming units (CFU) per cubic meter of air. DESIGN: We used Andersen two-stage samplers to collect bioaerosol samples from 24 houses in El Paso, Texas, using tryptic soy agar as the collection media, followed by the replicate plate method on Chapman Stone selective medium to isolate S. aureus. The Kirby-Bauer disk diffusion method was used to determine antibiotic resistance to ampicillin, penicillin, and cefaclor, which represent two distinct classes of antibiotics. RESULTS: The average recovered concentration of respirable heterotrophic organisms found outside each home was 345.38 CFU/m3, with an average of 12.63 CFU/m3 for S. aureus. The average recovered concentration of respirable heterotrophic organisms found inside each home was 460.23 CFU/m3, with an average of 15.39 CFU/m3 for S. aureus. The respirable S. aureus recovered from inside each home had an average resistance of 54.59% to ampicillin and 60.46% to penicillin. Presence of cefaclor-resistant and of multidrug-resistant S. aureus was the same, averaging 13.20% per house. The respirable S. aureus recovered from outside each home had an average resistance of 34.42% to ampicillin and 41.81% to penicillin. Presence of cefaclor-resistant and of multidrug-resistant S. aureus was the same, averaging 13.96% per house. CONCLUSIONS: This study indicates that antibiotic-resistant bioaerosols are commonly found within residential homes. Our results also suggest that resistant strains of airborne culturable S. aureus are present in higher concentrations inside the study homes than outside the homes.