Airborne Methicillin-resistant Staphylococcus Aureus Research Articles

Airborne methicillin-resistant Staphylococcus aureus, other bacteria, fungi, endotoxin, and dust in a pigeon exhibition

Pigeon breeding is associated with exposure to airborne microorganisms and endotoxin and with symptoms of the airways. Antibiotic resistance is a threat to human health. Some pigeons participate in national and international indoor exhibitions. This study aims to obtain knowledge about the potential human exposure to dust, endotoxin, fungi, and bacteria including the methicillin-resistant Staphylococcus aureus (MRSA) in a pigeon exhibition in Denmark. In walking areas for visitors, airborne microorganisms in different size fractions able to enter the airways were sampled and following identified. The average concentrations were: 5000 cfu fungi/m3, 1.8 × 104 cfu bacteria/m3, 37 endotoxin units/m3, and 0.18 mg dust/m3 air with the highest concentrations in-between rows with pigeon cages. The fungal species Wallemia sp. and Aspergillus versicolor and the bacterial species S. equorum and S. aureus were found in high concentrations. MRSA spa type t034 described to be associated with livestock was found in the air. Most of the S. aureus was present in the size fraction of 1.1–2.1 μm, which are particles able to enter the human terminal bronchi. In conclusion, fungi, bacteria, and endotoxin, respectively, were found in concentrations 10, 2000, and 200 times higher than outdoor references. The airborne bacteria in the exhibition were mainly species found previously in pigeon coops showing that the pigeons are the sources of exposure. The presence of airborne MRSA in the pigeon exhibition highlights the importance of also considering this environment as a potential place of exchange of resistant bacteria between animals and between animals and humans.

Measurement of dust-borne MRSA in pig farms using different approaches.

To obtain knowledge about (i) how to sample airborne methicillin-resistant Staphylococcus aureus (MRSA) and dust in the pig farm environment including effects of sampler on (a) measured exposure, (b) MRSA survival and (c) spatial and temporal variation in exposure, and (ii) the association between exposure to MRSA, dust and optical density OD. Airborne dust was sampled on five pig farms using five active and one passive samplers. Staphylococcus aureus and MRSA (as a subset of S. aureus) were quantified using selective agar media and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The Andersen sampler, electrostatic dust collectors (EDC), and Gesamtstaubprobenahme (GSP) and Institute of Occupational Medicine samplers with polycarbonate or Teflon filters were applicable for sampling airborne MRSA. The half-life of MRSA was not reduced by active sampling. A significant correlation was found between dust and S. aureus exposure within, but not between, farm section and farms. A significant spatial and temporal variation in dust and MRSA exposure was found within a stable. The dust sampling rate and the concentration of MRSA in the sampled dust decreased after 5days of sampling. Sampling using the GSP can be performed for 1h without affecting the following half-life of MRSA. Sampling for MRSA using the EDC should not exceed 3days due to overloading and the die-off of MRSA. The measurement of OD may be used as a proxy measure for dust exposure. To obtain knowledge about potential exposure, samples should be taken repeatedly and in different areas within a stable section. Sampling method, sampling time and number of samples taken, but not force of airflow on the filter, influence the measured potential exposure to MRSA and dust.

Controlling Transmission of MRSA to Humans During Short-Term Visits to Swine Farms Using Dust Masks.

The aim of the investigation was to determine the protective effect of wearing dust masks to prevent Methicillin-resistant Staphylococcus aureus (MRSA) contamination during a short-term visit in a MRSA-positive swine farm. A total of 118 human volunteers were randomly allocated to a group wearing masks and to the control group. On average, 9% of the participants wearing masks were MRSA-positive when leaving the farm compared to 62% of the participants not wearing masks. At day 1, 2, and 7 after the farm visit, none of those wearing masks were MRSA-positive. An odds ratio of 18.9 (CI: 6.4–56.2) for being MRSA-positive was found for those not wearing masks compared to those wearing masks when including the farm as random effect. None of the covariates (gender, age, and smoking) influenced the OR for being MRSA-positive when leaving the farm. This study shows that the use of dust masks gives a significant protection against nasal MRSA contamination after a short-term visit to a swine farm. In addition, 106 volunteers not wearing masks were investigated in order to provide an estimate of a contamination dose of airborne MRSA. Due to the high variation in the MRSA measurements, it was not possible to establish a stable estimate for this. Out of the 106 volunteers not wearing masks, 6, 7, and 3% tested MRSA-positive 1, 2, and 7 days after the farm visit, respectively.

Airborne MRSA and Total Staphylococcus aureus as Associated With Particles of Different Sizes on Pig Farms.

Airborne methicillin-resistant Staphylococcus aureus (MRSA) have previously been found on pig farms, which may lead to nasal deposition of MRSA in humans via inhalation. The anterior nares are the main niche for S. aureus, and S. aureus can cause, e.g. wound infection and pneumonia. The aim of this study was to acquire knowledge about the potential deposition of airborne MRSA, specifically, and of total S. aureus (including both methicillin-sensitive S. aureus and MRSA, in the following called S. aureus) in the different parts of the airways during occupancy on pig farms. Measurements of airborne MRSA and S. aureus were performed on four pig farms using a six and a three-stage sampler during different work tasks, such as high-pressure cleaning and everyday inspection. MRSA were quantified using MRSA-selective agar, and S. aureus were quantified using Staphylococcus selective agar. The identity of the bacteria were confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The geometric mean (GM) concentrations of MRSA and S. aureus were 447 cfu/m3 air and 1.8 × 103 cfu/m3 air, respectively. The highest concentrations of MRSA and S. aureus were found among pigs in a weaner stable and during high-pressure cleaning of an empty stable, respectively. The lowest concentrations of MRSA and S. aureus were found in a stable with sick pigs and in feed-storages, respectively. Most MRSA and S. aureus were associated with particles between 7 and 12 µm. On average, the particle size fractions potentially depositing in the upper airways constituted 70%, in the primary and secondary bronchi 22%, and in the terminal bronchi and alveoli 8% of the inhalable MRSA and S. aureus concentration. Across the sampled areas, the geometric mean diameter (Dg) of particles with MRSA and S. aureus were 7.2 and 6.4 µm, respectively, and no significant difference was found between these Dgs. The Dg of the airborne particles with the studied bacterium was significantly associated with the different locations on the farms. The largest Dgs were found in the air samples from the aisles and on the fence to the pens, while the smallest Dgs were found in samples from the pens among the pigs and in samples taken at greater distances from the pigs: in the hallway, feed-storage, and entry room. In conclusion, airborne MRSA and S. aureus were found in sample fractions potentially depositing in all six parts of the airways. However, the majority was found to potentially deposit in the upper airways. The concentration of airborne MRSA and S. aureus and MRSA, as well as the fraction potentially depositing in the different parts of the airways, depended on the specific work task being performed and the location on the farm.

Transmission of Methicillin-Resistant Staphylococcus aureus to Human Volunteers Visiting a Swine Farm.

ABSTRACTTransmission of methicillin-resistant Staphylococcus aureus (MRSA) from animals to humans is of great concern due to the implications for human health and the health care system. The objective was to investigate the frequency and duration of MRSA carriage in human volunteers after a short-term exposure in a swine farm. The experimental study included 34 human volunteers staying 1 h in a MRSA-positive swine farm in four trials. In two of the trials, the influence of farm work involving pig contact was studied using a crossover design. The quantities of MRSA in nasal swabs, throat swabs, and air samples were measured at different time points and analyzed in relation to relevant covariates. This investigation showed that, overall, 94% of the volunteers acquired MRSA during the farm visit. Two hours after the volunteers left the stable, the nasal MRSA count had declined to unquantifiable levels in 95% of the samples. After 48 h, 94% of the volunteers were MRSA-negative. Nasal MRSA carriage was positively correlated to personal exposure to airborne MRSA and farm work involving pig contact and negatively correlated to smoking. No association was observed between MRSA carriage and face touching behavior, nasal methicillin-susceptible Staphylococcus aureus (MSSA) carriage, age, or gender. The increase in human MRSA carriage among the volunteers with pig contact seems to be dependent on the increased concentration of airborne MRSA of the surrounding air and not directly on physical contact with pigs. MRSA was not detected in any of the throat samples.IMPORTANCE The experimental approach made it possible to elucidate the contributions of airborne MRSA levels and farm work to nasal MRSA carriage in a swine farm. Short-term exposure to airborne MRSA poses a substantial risk for farm visitors to become nasal carriers, but the carriage is typically cleared within hours to a few days. The risk for short-term visitors to cause secondary transmissions of MRSA is most likely negligible due to the observed decline to unquantifiable levels in 95% of the nasal samples after only 2 h. The MRSA load in the nose was highly correlated to the amount of MRSA in the air and interventions to reduce the level of airborne MRSA or the use of face masks might consequently reduce nasal contamination.

Detection of Airborne Methicillin-Resistant Staphylococcus aureus Inside and Downwind of a Swine Building, and in Animal Feed: Potential Occupational, Animal Health, and Environmental Implications

ABSTRACTAerosolized methicillin-resistant Staphylococcus aureus (MRSA) was sampled inside and downwind of a swine facility. Animal feed was sampled before and after entry into the swine facility. Aerosolized particles were detected using an optical particle counter for real-time measurement and with an Andersen sampler to detect viable MRSA. Molecular typing and antimicrobial susceptibility testing were performed on samples collected. Viable MRSA organisms isolated inside the swine facility were primarily associated with particles >5 µm, and those isolated downwind from the swine facility were associated with particles <5 µm. MRSA isolates included spa types t008, t034, and t5706 and were resistant to methicillin, tetracycline, clindamycin, and erythromycin. Animal feed both before and after entry into the swine facility tested positive for viable MRSA. These isolates were of similar spa types as the airborne MRSA organisms. Air samples collected after power washing with a biocide inside the swine facility resulted in no viable MRSA organisms detected. This pilot study showed that the ecology of MRSA is complex. Additional studies are warranted on the maximum distance that viable MRSA can be emitted outside the facility, and the possibility that animal feed may be a source of contamination.

Evaluation of the Filtration Efficiency of the N95 Filtering Facepiece Respirator for Airborne Methicillin-Resistant Staphylococcus aureus

<abstract> <bold><sc>Abstract.</sc></bold> Airborne methicillin-resistant Staphylococcus aureus (MRSA) was detected inside a swine facility that presented a risk of respiratory colonization and infection to swine and swine workers. Viable airborne MRSA was sampled using an Andersen cascade impactor, and total airborne particulates were sampled using an optical particle counter. The filter efficiency of the N95 filtering facepiece respirator (FFR) was evaluated to determine its effectiveness for airborne MRSA. Our study showed that the filter for the N95 FFR had efficiency greater than 95% for airborne MRSA.

Airborne methicillin-resistant Staphylococcus aureus in the indoor environment of King Abdullah University Hospital, Jordan

Methicillin-resistant Staphylococcus aureus (MRSA) is seen with increasing frequency in hospitals and is considered as a major cause of hospital-acquired infection. The objectives of this study were to isolate and characterize the airborne MRSA in different wards of a referral university hospital. Thirty-four air samples of 100 litres volume/min were collected by a microbiological air sampler, then impacted on trypticase soy agar (TSA) and incubated at 37℃ for 48 h. Recovered colonies were identified by standard methods. From all S. aureus, 9.3% was identified as MRSA which comprised 4.2%, 3.1% and 2% in the adult and nursery intensive care units, and operating theatres (ICU, NICU and OT, respectively). MRSA isolates were remarkably susceptible (87.1%) to each of amikacin, chloramphenicol, imipenem and rifampin. MRSA isolates were shown in all units with minimum inhibitory concentration value of &gt;256, 32 and 6 µg/l in ICU, OT and NICU, respectively. Polymerase chain reaction analysis of all MRSA isolates indicated the amplification of the mec A gene. It is concluded that MRSA was isolated from all units making eradication of MRSA a target hard to achieve. However, the antibiotic resistance profile of the MRSA isolates looks promising leaving a room to combat nosocomial infections.

The Correlation between Airborne Methicillin-resistant Staphylococcus aureus with the Presence of MRSA Colonized Patients in a General Intensive Care Unit

Air sampling directly onto a methicillin-resistant Staphylococcus aureus (MRSA) selective agar was performed at six locations three times weekly over a period of 32 weeks in a new, initially MRSA-free Intensive Care Unit to examine if MRSA is present in air sample cultures and, if so, whether it is affected by the number of MRSA colonized patients present. A total of 480 air samples were collected on 80 days. A total of 39/480 (8.1%) samples were found to be MRSA positive of which 24/160 (15%) positive air samples were from the single rooms, where MRSA colonised patients were isolated, and 15/320 (4.7%) were from the open bed areas. A significant correlation was found between the daily number of MRSA colonized or infected patients in the Unit and the daily number of MRSA positive air samples cultures obtained (r2=0.128; P<0.005). The frequency of positive cultures was significantly higher in the single rooms than in the open bed areas (relative risk=3.2; P<0.001). The results from one of the single rooms showed a strong correlation between the presence of MRSA patients and MRSA positive air samples (relative risk=11.4; P<0. 005). Our findings demonstrate that the presence of airborne MRSA in our unit is strongly related to the presence and number of MRSA colonized or infected patients in the Unit.

Significance of airborne transmission of methicillin-resistant Staphylococcus aureus in an otolaryngology-head and neck surgery unit.

To quantitatively investigate the existence of airborne methicillin-resistant Staphylococcus aureus (MRSA) in a hospital environment and to perform phenotyping and genotyping of MRSA isolates to study MRSA epidemiology. Prospective surveillance of patients with MRSA infections or colonizations was performed, as was an observational study of environmental airAirborne samples were taken by an air sampler; samples were obtained from object surfaces by stamping or swabbing. Epidemiological study of MRSA isolates was performed with an antibiotic susceptibility test, coagulase typing, and pulsed-field gel electrophoresis. Three single-patient rooms in a 37-bed otolaryngology-head and neck surgery unit. Three patients with squamous cell head and neck cancer were observed to have been colonized or infected with MRSA after surgery. The MRSA samples were collected from the air in single-patient rooms during both a period of rest and when bedsheets were being changed. Isolates of MRSA were detected in all stages (from stage 1 [>7 microm] to stage 6 [0.65-1.1 microm]). About 20% of the MRSA particles were within a respirable range of less than 4 microm. Methicillin-resistant S aureus was also isolated from inanimate environments, such as sinks, floors, and bedsheets, in the rooms of the patients with MRSA infections as well as from the patients' hands. An epidemiological study demonstrated that clinical isolates of MRSA in our ward were of one origin and that the isolates from the air and from inanimate environments were identical to the MRSA strains that caused infection or colonization in the inpatients. Methicillin-resistant S aureus was recirculated among the patients, the air, and the inamimate environments, especially when there was movement in the rooms. Airborne MRSA may play a role in MRSA colonization in the nasal cavity or in respiratory tract MRSA infections. Measures should be taken to prevent the spread of airborne MRSA to control nosocomial MRSA infection in hospitals.

Food-initiated outbreak of methicillin-resistant Staphylococcus aureus analyzed by pheno- and genotyping.

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) involving 27 patients and 14 health-care workers (HCW) was studied. The outbreak started in the hematology unit of the University Hospital Rotterdam, Dijkzigt, The Netherlands, and spread to the surgical unit. Twenty-one patients (77.8%) developed clinical disease, and five died. Subsequently, MRSA was detected in food and in the throat of one of the HCW who prepared food for hematology patients. Food contaminated by an HCW most likely caused the first case of MRSA septicemia. This route of transmission has not been described before. The outbreak strain was probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne MRSA transmission played an important role in disseminating the organism. The outbreak was controlled within 6 months by intensifying surveillance, temporarily closing the affected wards, treating carriers, and instituting an MRSA ward outside the hospital. Phage typing, insertion sequence probing, protein A gene typing, and DNA fingerprinting by PCR revealed that all outbreak-related isolates were identical. By pulsed-field gel electrophoresis, all but one of the outbreak-related isolates were determined to be identical. Protein A gene typing identified numerous (11) repeat units in all outbreak-related isolates, which supports the suggestion that the outbreak strain may have been more virulent and more transmissible than other MRSA strains. Pheno- and genotyping studies underlined the value of DNA fingerprinting methods for investigation of MRSA epidemiology. Optimal discriminatory power was achieved by combining the results of four genotyping methods.