Ultraviolet germicidal irradiation susceptibility of methicillin-resistant Staphylococcus aureus compared with methicillin-susceptible S. aureus.

Antibiotic misuse and overuse in both the healthcare and agricultural fields have dramatically increased the prevalence of antibiotic resistance in human pathogens. Two strains of methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43330 and a wild-type) and 1 strain of methicillin-susceptible S. aureus (ATCC 25923) were challenged (9 runs in triplicate) in a preliminary study with ultraviolet germicidal irradiation (UVGI) doses ranging from 0.25 to 3.00 mJ/cm(2). The mean percent kill was calculated for each strain when compared with the control plates (no exposure to UVGI). Then, each strain was challenged (22 runs in triplicate) with UVGI doses of 2.00, 2.50, and 3.00 mJ/cm(2). The results suggest a difference between the doses required to disinfect surfaces with each strain. Assuming a standard error rate of α = 0.05, there was a significant difference in variance between the MRSA (ATCC 43330 and wild type) strains and the S. aureus (ATCC 25923) methicillin-susceptible strain.

A waste walk through clinical pharmacy: how do the 'seven wastes' of Lean techniques apply to the practice of clinical pharmacists.

AIMS AND OBJECTIVES: This study used a 'Lean' technique, the 'waste walk' to evaluate the activities of clinical pharmacists with reference to the seven wastes described in 'Lean' including 'defects', 'unnecessary motion', 'overproduction', 'transport of products or material', 'unnecessary waiting', 'unnecessary inventory' and 'inappropriate processing'. The objectives of the study were to categorise the activities of ward-based clinical pharmacists into waste and non-waste, provide detail around what constitutes waste activity and quantify the proportion of time attributed to each category. SETTING: This study was carried out in a district general hospital in the North West of England. METHOD: Staff were observed using work-sampling techniques, to categorise activity into waste and non-waste, with waste activities being allocated to each of the seven wastes described earlier and subdivided into recurrent themes. KEY FINDINGS: Twenty different pharmacists were observed for 1 h on two separate occasions. Of 1440 observations, 342 (23.8%) were categorised as waste with 'defects' and 'unnecessary motion' accounting for the largest proportions of waste activity. CONCLUSION: Observation of clinical pharmacists' activities has identified that a significant proportion of their time could be categorised as 'waste'. There are practical steps that could be implemented in order to ensure their time is used as productively as possible. Given the challenges facing the UK National Health Service, the adoption of 'Lean' techniques provides an opportunity to improve quality and productivity while reducing costs.

Performance evaluation of selected n95 respirators and surgical masks when challenged with aerosolized endospores and inert particles.

The objective of this study was to assess how the relative efficiency of N95 respirators and surgical masks might vary with different challenge aerosols, utilizing a standardized manikin head form as a surrogate to human participation. A Collision nebulizer aerosolized B. anthracis Sterne strain endospores and polystyrene latex (PSL) particles to evaluate 11 models of N95 respirators and surgical masks. An automated breathing simulator, calibrated to normal tidal volume and active breathing rate, mimicked human respiration. A manikin head form with N95 respirators or surgical masks, and manikin head form without N95 respirators or surgical masks were placed in the bioaerosol chamber. An AGI-30 sampler filled with phosphate buffered water was fitted behind the mouth of each manikin head form to collect endospore bioaerosol samples. PSL aerosols concentrations were quantified by an ARTI Hand Held Particle Counter. Geometric Mean (GM) relative efficiency of N95 respirators and surgical masks challenged with endospore bioaerosol ranged from 34-65%. In PSL aerosol experiments, GM relative efficiency ranged from 35-64% for 1.3 µm particles. GM filtration efficiency of all N95 and surgical N95 respirators filter media evaluated was ≥99% when challenged with particles ≥0.1 µm. GM filtration efficiency of surgical mask filter media ranged from 70-83% with particles ≥0.1 µm and 74-92% with 1.3 µm PSL particles. Relative efficiencies of N95 respirators and surgical masks challenged with aerosolized B. anthracis endospores and PSL were similar. Relative efficiency was similar between N95 respirators and surgical masks on a manikin head form despite clear differences in filtration efficiency. This study further highlights the importance of face seal leakage in the respiratory protection provided by N95 respirators, and demonstrates it on a human surrogate.

Coarse and fine culturable fungal air concentrations in urban and rural homes in Egypt.

The main objective of the present study was to assess culturable airborne fungal concentrations, and types in different seasons. Two-stage viable impactor samplers were used with malt extract agar medium as the collection media. Culturable airborne fungal concentrations were collected indoors and outdoors of 43 homes in urban and rural environments from November 2008 to October 2009 in Egypt. Fungal concentrations were significantly higher in the rural environment than the urban environment. The median indoor and outdoor total fungal concentrations were 608 and 675 CFU/m3 in the urban environment and 1,932 and 1,872 CFU/m3 in the rural environment, respectively. The greatest concentrations were found in the autumn and spring season. Indoor and outdoor concentrations were significantly correlated (P < 0.001). The highest concentrations were observed in the fungal size range of <8 µm (fine fraction). The indoor/outdoor (I/O) ratios were not statistically different between seasons. Alternaria, Aspergillus, Cladosporium, Penicillium and yeasts were the predominant genera indoors and outdoors, and the abundance of genera varied by season and region. This study is of a potential interest as little reported research on the indoor fungal air quality from Egypt.

Seasonal evaluation of fine and coarse culturable bacterial aerosols from residences within a rural and an urban city in Egypt.

Non-complaint Egyptian homes were examined to determine the residential culturable airborne bacterial concentrations so that these could be used as comparisons in indoor air quality investigations. Concentrations of airborne bacteria were investigated in 26 urban flats across Cairo and 17 rural flats in the Dakahlia governorate. Air samples were collected using a two-stage viable cascade impactor sampler, dividing particles into coarse (>8 µm) and fine (<8 µm) sizes. For urban flats, the year's median indoor and comparison site concentrations were 9133 CFU/m(3) and 9423 CFU/m(3), respectively. For rural flats, the year's median indoor and comparison site concentrations were 15,915 CFU/m(3) and 10,859 CFU/m(3), respectively. The median indoor bacterial concentrations increased in winter and spring compared to autumn and summer. Winter months had the greatest median concentration for coarse indoor organisms, whereas spring had the largest for the fine indoor organisms. Fine bacterial concentration composed more than 60% of the indoor bacterial fraction.

Effectiveness of selected surgical masks in arresting vegetative cells and endospores when worn by simulated contagious patients.

OBJECTIVE: The objective of this study was to quantify the effectiveness of selected surgical masks in arresting vegetative cells and endospores in an experimental model that simulated contagious patients. SETTING: Laboratory. METHODS: Five commercially available surgical masks were tested for their ability to arrest infectious agents. Surgical masks were placed over the nose and mouth of mannequin head forms (Simulaids adult model Brad CPR torso). The mannequins were retrofitted with a nebulizer attached to an automated breathing simulator calibrated to a tidal volume of 500 mL/breath and a breathing rate of 20 breaths/min, for a minute respiratory volume of 10 L/min. Aerosols of endospores or vegetative cells were generated with a modified microbiological research establishment-type 6-jet collision nebulizer, while air samples were taken with all-glass impinger (AGI-30) samplers downstream of the point source. All experiments were conducted in a horizontal bioaerosol chamber. RESULTS: Mean arrestance of bioaerosols by the surgical masks ranged from 48% to 68% when the masks were challenged with endospores and from 66% to 76% when they were challenged with vegetative cells. When the arrestance of endospores was evaluated, statistical differences were observed between some pairs, though not all, of the models evaluated. There were no statistically significant differences in arrestance observed between models of surgical masks challenged with vegetative cells. CONCLUSIONS: The arrestance of airborne vegetative cells and endospores by surgical masks worn by simulated contagious patients supports surgical mask use as one of the recommended cough etiquette interventions to limit the transmission of airborne infectious agents.

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.

Feasibility of selected prophylactic barriers in arrestance of airborne bacterial vegetative cells and endospores.

BACKGROUND: Transmission of infection by airborne agents is a risk for health care personnel, patients, and visitors. This risk is heightened in regions without access to environmental controls and personal protective equipment. The ability of 2 prophylactic barriers (ie, semitransparent netting for insect control) to arrest bioaerosols was assessed for potential use within the malarial zones. METHODS: Barriers (pore sizes of 0.8 mm and 0.25 mm) were challenged with bioaerosols of vegetative cells and endospores of Bacillus anthracis strain Sterne 34F2 using a bioaerosol chamber. Barriers were also challenged with airborne inert polystyrene latex particles of known diameters (0.1, 0.43, 0.6, 1.3, 3.2, and 8.0 µm), and the arrestance provided by barrier with the 0.25 mm pore size was expressed as a function of aerodynamic diameter of challenge aerosols. RESULTS: Barrier with the 0.8 mm pore size provided no significant arrestance of aerosols, whereas the barrier with the 0.25 mm pore size provided an 8% arrestance of vegetative cells and a 13% arrestance of endospores. No arrestance at or below the 0.6 µm particle size was observed. CONCLUSION: The level of arrestance provided by these prophylactic barriers does not justify their use as a sole method of preventing transmission.

Emergency re-admissions to hospital due to adverse drug reactions within 1 year of the index admission.

AIM: The proportion of re-admissions to hospital caused by ADRs is poorly documented in the UK. The aim of this study was to evaluate the impact of ADRs on re-admission to hospital after a period as an inpatient. METHODS: One thousand patients consecutively admitted to 12 wards were included. All subsequent admissions for this cohort within 1 year of discharge from the index admission were retrospectively reviewed. RESULTS: Of the 1000 patients included, 403 (40.3%, 95% CI 39.1, 45.4%) were re-admitted within 1 year. Complete data were available for 290 (70.2%) re-admitted patients, with an ADR contributing to admission in 60 (20.8%, 95% CI 16.4, 25.6%) patients. Presence of an ADR in the index admission did not predict for an ADR-related re-admission (10.5% vs. 7.2%, P=0.25), or re-admission overall (47.2% vs. 41.2%, P=0.15). The implicated drug was commenced in the index admission in 33/148 (22.3%) instances, with 37/148 (25%) commenced elsewhere since the index admission. Increasing age and an index admission in a medical ward were associated with a higher incidence of re-admission ADR. The most frequent causative drugs were anti-platelets and loop diuretics, with bleeding and renal impairment the most frequent ADRs. Over half (52/91, 57.1%) of the ADRs were judged to be definitely or possibly avoidable. CONCLUSIONS: One fifth of patients re-admitted to hospital within 1 year of discharge from their index admission are re-admitted due to an ADR. Our data highlight drug and patient groups where interventions are needed to reduce the incidence of ADRs leading to re-admission.

Interpreting adverse drug reaction (ADR) reports as hospital patient safety incidents.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Adverse drug reactions (ADRs) are a reporting category in the National Patient Safety Agency (NPSA) incident reporting system, though the Medicines and Healthcare Products Regulatory Agency (MHRA) pharmacovigilance system is the more established method for collecting ADR data. WHAT THIS STUDY ADDS: The majority of ADRs were shown to be of moderate risk to the patient, though some have a severe or catastrophic impact. Classification and reporting of ADRs according to NPSA guidance is possible but offers limited additional value to efforts to improve patient safety over and above the Yellow Card Scheme. AIM: In the UK, the National Patient Safety Agency (NPSA) includes adverse drug reactions as a reporting category, while the MHRA Yellow Card Scheme also collects data regarding adverse drug reactions (ADRs). In this study, we aimed to assess ADRs using NPSA criteria and discuss the resulting implications. METHODS: ADRs identified in a 6-month prospective study of 3695 inpatient episodes were assessed according to their impact on the patient and on the organization, using tools developed by the NPSA. RESULTS: Seven hundred and thirty-three (100%) ADRs were assessed. In terms of impact on the patient, 537 (73.3%) were categorized as 'low' (minor treatment), 181 (24.7%) as 'moderate' (moderate increase in treatment, no permanent harm), 14 (1.91%) as 'severe' (permanent harm) and 1 (0.14%) was categorized as 'catastrophic' (direct cause of death). In terms of impact on the organization, none was categorized as 'no harm/no risk', 508 (69.3%) as 'insignificant', 188 (25.6%) as 'minor', 25 (3.4%) as 'moderate', 12 (1.6%) as 'major' and none was classed as 'catastrophic'. Less than 2% of ADRs would be eligible for detailed analysis according to the NPSA guidance. The ADRs that cause incidents of greater significance relate to bleeding, renal impairment and Clostridium difficile infection. CONCLUSIONS: Classification of ADRs according to NPSA guidance offers limited additional value over and above that offered by the Yellow Card System. A consistent message needs to be sent to prospective reporters of ADRs; the availability of more than one system is likely to confuse reporters and does not aid patient safety.

A study of the use of medicine lists in medicines reconciliation: please remember this, a list is just a list.

OBJECTIVES: Medication history-taking is recognised as a potential source of medication errors and is the subject of the first National Patient Safety Agency/National Institute for Health and Clinical Excellence Patient Safety Guidance. Medication lists are suggested as a way of improving medicines reconciliation, but, anecdotally, can falsely reassure prescribers that they have an accurate list of medicines if used in isolation. METHODS: Patients in possession of a medicines list on admission to hospital were approached as part of routine care. Data were collated regarding medication-history discrepancies, their source and whether a prescription amendment was made. KEY FINDINGS: One hundred and twenty patients were reviewed and the median time for pharmacists to complete medicines reconciliation was 15 min. Eighty-three patients (69.2%) had only one medication list, 31 (26%) had two, five (4%) had three and one patient (0.8%) had four lists. In total, 447 discrepancies were identified of which 49 (11.0%) were initiated by the patient, including 32 (65.3%) to adjust a dosage regimen or not to comply with a dosing regime. For the 279 (62.4%) discrepancies attributable to secondary care staff, 119 (42.6%) prescribed medicines were omitted unintentionally. For the 119 (26.6%) discrepancies attributable to the primary care medicines lists, 48 (40.3%) related to inadequate or inaccurate information regarding medicine doses, frequency, strength or form. Each patient required a mean of 1.6 amendments to their prescription despite bringing a list of medicines with them. CONCLUSIONS: Medication lists should be interpreted with caution and assessed in combination with other sources of information, particularly the patient or their carer. Strategies to improve medicines reconciliation on admission to hospital are still needed and a single electronic patient record encompassing primary and secondary care medication records would be a positive step forward.

Evaluation of respiratory symptoms and their possible association with residential indoor bioaerosol concentrations and other environmental influences.

The study discussed here evaluated the presence of self-reported respiratory symptoms and their association with indoor bioaerosol concentrations over a year-long study in the El Paso, Texas, region. The authors collected air samples from homes to assess seasonal differences in bacterial and fungal bioaerosol concentrations. They distributed a health questionnaire to the participating homeowner during each seasonal air sampling. The authors used this questionnaire to assess whether the homeowners were suffering from specific symptoms prior to each sampling. Descriptive statistics and logistic regressions were conducted to model the relationship among "high" reporters of symptoms, bioaerosols, and environmental factors. The authors collected evidence to support an association between indoor respirable bacterial concentrations and homeowners that reported at least eight respiratory symptoms (odds ratio [OR] = 1.10, p = .045). Smoking status, indoor humidity, and season also displayed associations with homeowners that reported at least eight respiratory symptoms (current smokers OR = 3.3, p = .042; indoor humidity OR = 1.5, p = .030; spring season OR = 7.2, p = .001; fall season OR = 3.4, p = .008).

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.

Adverse drug reactions in hospital in-patients: a prospective analysis of 3695 patient-episodes.

Adverse drug reactions (ADRs) are a major cause of hospital admissions, but recent data on the incidence and clinical characteristics of ADRs which occur following hospital admission, are lacking. Patients admitted to twelve wards over a six-month period in 2005 were assessed for ADRs throughout their admission. Suspected ADRs were recorded and analysed for causality, severity and avoidability and whether they increased the length of stay. Multivariable analysis was undertaken to identify the risk factors for ADRs. The 5% significance level was used when assessing factors for inclusion in multivariable models. Out of the 3695 patient episodes assessed for ADRs, 545 (14.7%, 95% CI 13.6-15.9%) experienced one or more ADRs. Half of ADRs were definitely or possibly avoidable. The patients experiencing ADRs were more likely to be older, female, taking a larger number of medicines, and had a longer length of stay than those without ADRs. However, the only significant predictor of ADRs, from the multivariable analysis of a representative sample of patients, was the number of medicines taken by the patient with each additional medication multiplying the hazard of an ADR episode by 1.14 (95% CI 1.09, 1.20). ADRs directly increased length of stay in 147 (26.8%) patients. The drugs most frequently associated with ADRs were diuretics, opioid analgesics, and anticoagulants. In conclusion, approximately one in seven hospital in-patients experience an ADR, which is a significant cause of morbidity, increasing the length of stay of patients by an average of 0.25 days/patient admission episode. The overall burden of ADRs on hospitals is high, and effective intervention strategies are urgently needed to reduce this burden.

Attitudes and opinions of nursing and medical staff regarding the supply and storage of medicinal products before and after the installation of a drawer-based automated stock-control system.

OBJECTIVES: This study assessed the attitudes of Emergency Department (ED) staff regarding the introduction of an automated stock-control system. The objectives were to determine attitudes to stock control and replenishment, speed of access to the system, ease of use and the potential for future uses of the system. The study was carried out in the Countess of Chester Hospital NHS Foundation Trust (COCH) ED, which is attended by over 65,000 patients each year. METHODS: All 68 ED staff were sent pre-piloted, semi-structured questionnaires and reminders, before and after automation of medicines stock control. KEY FINDINGS: Pre-implementation, 35 staff (66.1% of respondents) reported that problems occurred with access to medicine storage keys 'very frequently' or 'frequently'. Twenty-eight (52.8%) respondents 'agreed' or 'strongly agreed' that medicines were quickly accessed, which rose to 41 (77%) post-automation (P < 0.001). Improvement was reported in stock replenishment and storage of stock injections and oral medicines, but there were mixed opinions regarding storage of bulk fluids and refrigerated items. Twenty-seven (51.9%) staff reported access to the system within 1 min and 17 (32.7%) staff reported access within 1-2 min. The majority of staff found the system 'easy' or 'very easy' to use and there was a non-significant relationship between previous use of information technology and acceptance of the system. CONCLUSIONS: From a staff satisfaction perspective, automation improved medicines storage, security and stock control, and addressed the problem of searching for keys to storage areas. Concerns over familiarity with computers, queuing, speed of access and an improved audit trail do not appear to have been issues, when compared with the previous manual storage of medicines.

Characterization of seasonal indoor and outdoor bioaerosols in the arid environment of El Paso, Texas.

The authors conducted a study in the El Paso, Texas, region to assess the seasonal bioaerosol concentrations in a convenience sample of one-story residences. The authors sampled the same houses for each season over the course of a year (March 2005 to February 2006) to determine bacterial and fungal concentrations. They used a two-stage ambient culturable sampler system to collect the bioaerosol samples. They took indoor and outdoor bioaerosol samples and studied meteorological conditions for each house at each season. The study found that most of the measured bioaerosol concentrations differed statistically by season (p < .05). The greatest concentrations throughout the year were found to occur in fine-sized indoor bacteria during the winter. Meteorological conditions were found not to significantly influence bioaerosol concentrations throughout the year.

Seasonal fine and coarse culturable fungal constituents and concentrations from indoor and outdoor air samples taken from an arid environment.

This study was undertaken to determine the normal indoor and outdoor airborne culturable fungal constituents and concentrations of an arid environment. Air samples were taken with two-stage, ambient, culturable sampler systems and analyzed for nine specific fungal genera from 50 homes as a repeated measure during each season of the year. These homes had no previous histories of indoor air quality issues. This study detected seasonal differences for the arid environment between different culturable fungal concentrations across the two size ranges. The highest concentrations were during fall, in the outdoor fine-size range. The lowest concentrations were the indoor coarse concentrations in the spring. From this study it can be concluded that Cladosporium spp. had the highest concentrations during fall in an arid environment. The overall findings suggest that Cladosporium had concentrations greater than the other genera evaluated, specifically, the fall outdoor fine concentrations. Seasonality was found to be a key factor in determining the variability of fungal constituents and concentrations within the arid indoor and outdoor environments. The fine-size range was 12 times and 6 times greater than the coarse-size range for indoor and outdoor samples, respectively, which accounted for the majority of fungal organisms. In addition, the results from this study in an arid climate differ from those conducted in a moister climate.

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.

Isolation of antibiotic-resistant bacteria from the air plume downwind of a swine confined or concentrated animal feeding operation.

OBJECTIVE: In this study we evaluated the levels of antibiotic- and multidrug-resistant bacteria in bioaerosols upwind, within, and downwind at locations 25 m, 50 m, 100 m, and 150 m from a swine confined animal feeding operation. DESIGN: We used Andersen two-stage samplers to collect bacterial samples, the replicate plate method to isolate organisms, and the Kirby-Bauer disk diffusion method to determine antibiotic resistance. RESULTS: The percentage of organisms resistant to at least two antibiotic classes and all four classes evaluated were, respectively, 2.1 and 3.0 times higher inside (n = 69) than upwind (n = 59) of the facility. Staphylococcus aureus was the most prevalent organism recovered. Concentrations of antibiotic-resistant S. aureus decreased with increasing distance from the facility. Using Fisher's exact methods, the change in distribution of antibiotic resistance profiles for each antibiotic was statistically significant (oxytetracycline, p = 0.010; tetracycline, p = 0.014; ampicillin, p = 0.007; erythromycin, p = 0.035); however, this relationship was not seen with lincomycin and penicillin (p > 0.05) . In addition, the levels of antibiotic-resistant S.aureus 25 m downwind were significantly greater than the levels from samples taken upwind from the facility for the same four antibiotics (p < 0.05) . The percentage of resistant group A streptococci and fecal coliform increased within the facility compared with upwind values for all antibiotics evaluated,except for lincomycin. The percentage of resistant total coliform organisms increased within the facility compared with upwind values for oxytetracycline and tetracycline. CONCLUSIONS: Bacterial concentrations with multiple antibiotic resistances or multidrug resistance were recovered inside and outside to (at least) 150 m downwind of this facility at higher percentages than upwind. Bacterial concentrations with multiple antibiotic resistances were found within and downwind of the facility even after subtherapeutic antibiotics were discontinued. This could pose a potential human health effect for those who work within or live in close proximity to these facilities.

Bacterial plume emanating from the air surrounding swine confinement operations.

The objective of this study was to evaluate the levels of bacteria in the air plume immediately upwind at 25 m and downwind at locations 25 m, 50 m, 100 m, and 150 m from a confined animal feeding operation (CAFO). It was hypothesized that this would give insight into determining the maximal distance that bacterial organisms release from a CAFO could travel, which would be important in determining the optimal siting distance for future CAFO in relation to high population areas. The Andersen two-stage sampler was used to collect all of the bacterial samples from the animal confinement facilities. The data show a marked increase in bacterial CFUs/m3 inside the facility (18,132 CFU/m3 average) versus upwind (63 CFU/m3 average) anda steady down wind decrease out to approximately 150 m. Staphylococcus aureus was found to account for 76% of the organisms recovered. We conclude that the optimal placement of a swine CAFO would be at least 200 m from a residential area.