Dynamic Transmission of Staphylococcus Aureus in the Intensive Care Unit

Abstract

Staphylococcus aureus is an important bacterial pathogen. This study utilized known staphylococcal epidemiology to track S. aureus between patients, surfaces, staff hands and air in a ten-bed intensive care unit (ICU). Methods: Patients, air and surfaces were screened for total colony counts and S. aureus using dipslides, settle plates and an MAS-100 slit-sampler once a month for 10 months. Data were modelled against proposed standards for air and surfaces, and ICU-acquired staphylococcal infection. Whole-cell genomic typing (WGS) demonstrated possible transmission pathways between reservoirs. Results: Frequently touched sites were more likely to be contaminated (>12 cfu/cm2; p = 0.08). Overall, 235 of 500 (47%) sites failed the surface standard (≤2.5 cfu/cm2); 20 of 40 (50%) passive air samples failed the “Index of Microbial Air” standard (2 cfu/9 cm plate/h), and 15/40 (37.5%) air samples failed the air standard (<10 cfu/m3). Settle plate data were closer to surface counts than automated air data; the surface count most likely to reflect pass/fail rates for air was 5 cfu/cm2. Surface counts/bed were associated with staphylococcal infection rates (p = 0.012). Of 34 pairs of indistinguishable S. aureus, 20 (59%) showed autogenous transmission, with another four (12%) occurring between patients. Four (12%) pairs linked patients with hand-touch sites and six (18%) linked airborne S. aureus, staff hands and hand-touch sites. Conclusion: Most ICU-acquired S. aureus infection is autogenous, while staff hands and air were rarely implicated in onward transmission. Settle plates could potentially be used for routine environmental screening. ICU staphylococcal infection is best served by admission screening, systematic cleaning and hand hygiene.

Inanimate Surfaces and Air Contamination with Multidrug Resistant Species of Staphylococcus in the Neonatal Intensive Care Unit Environment

“…This failure rate of air cleaning is higher than that found by Adams and Dancer [ 17 ], who evaluated the contamination of a hospital environment that used mechanically ventilated air, with 10 air changes per hour, and constant temperature, and humidity. In their study, half of the exposed plates produced counts of >1 CFU/plate and the hygiene failure rate was 50%.…”

“…multidrug resistance (MDR) is responsible for 2% to 5% of HAIs in the NICU and causes significant neonatal morbidity and mortality (20–35%) [ 11 , 15 , 16 ]. These microorganisms can survive for long periods on inanimate surfaces and in the air [ 3 , 15 , 17 ]. Studies have shown that the persistence of MDR isolates in the environment can vary from 7 days to 5 years, depending on the type of surface, humidity, and temperature, persisting longer on dry surfaces [ 3 , 18 ].…”

“…The transfer of these microorganisms between the environment and patients has been demonstrated in the literature [ 3 , 7 , 17 ], and emphasizes the importance of knowing the reservoirs of hospital microbiota. Despite the relevance of the subject, studies of this type in the NICU are scarce; therefore, the purpose of this study was to identify the MDR species of Staphylococcus on inanimate surfaces, in air, and in clinical samples and analyze the risk factors that correlate with the occurrence of infections caused by these microorganisms in an NICU.…”

Potential application of novel technology developed for instant decontamination of personal protective equipment before the doffing step

“…Hospital infections are caused by factors such as environmental contamination, frequent handling of contaminated material, and the ability of microorganisms to survive for prolonged periods on different types of surfaces [ 1 , 92 ]. Within the hospital environment, sodium hypochlorite is the most widely used disinfectant because it has broad-spectrum antimicrobial activity, considering Gram-positive and Gram-negative bacteria and fungi [ 83 ] as well as demonstrated virucidal activity [ 93 ].…”

Bacterial Contamination of Equine Dentistry Equipment—Effect of Cleaning and Disinfection

“…It can be assumed that a high bacterial load is an indicator of the presence of potentially pathogenic microorganisms. In a study by Adams et al [ 27 ] investigating the occurrence of Staphylococcus aureus in a human intensive care unit, most Staphylococcus aureus were detected on heavily contaminated hand-touch sites. This study has shown that dental procedures, using handpieces, contaminate the equipment and the surrounding environment, with a potentially increased risk of transmission of pathogens between patients, staff, and facilities.…”