Table 1.
Transmission dynamics from floor surfaces or environmental ground contamination to cause human infection
| Study no. | Transmission pathway | First author, year, country | Study design | Setting (N) | Method | Source of contamination | Contaminant | Measurement | Predictors of contamination |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Direct via human contact, hospital | Verde, 2015, Portugal [12] | Obs. | Three community hospitals (3177 patients) | Microbiological air sampling from hospital areas | Aerosolized floor microorganisms | Gram-positive cocci and fungus | Airborne contamination | Higher traffic areas and less routine cleaning predicted contamination |
| 2 | Direct via human contact, hospital | Andersson, 2012, Sweden [13] | Obs. | Hospital operation room (91 air samples) | Microbiological air sampling during surgery | Aerosolized floor microorganisms | Bacterial pathogens | Airborne contamination | Increased contamination with person traffic and duration of surgery |
| 3 | Direct via human contact, hospital | Anderson, 1982, USA [15] | Obs. | Paediatric patient rooms (62 rooms) | Microbiological air contamination of carpeting vs. tiles | Aerosolized floor microorganisms | HAI organisms | Airborne contamination | Higher aerosolization contamination above carpeted flooring |
| 4 | Direct via human contact, hospital | Limmathurotsakul, 2013, Thailand [14] | Obs. | Hospital patients (286 cases, 513 controls) | Cases and non-infected controls were compared | Soil and water in hospital environment | Burkholderia pseudomallei | Floor contamination | Exposure to soil or water increased melioidosis risk [OR 1·4 (0·8–2·6)] |
| 5 | Direct via human contact, hospital | Whyte, 2013, Glasgow [16] | Exp. | Hospital simulation room (100 steps) | Microbiological air sampling by human walking | Aerosolized floor microorganisms | MCP | Floor contamination | Walking significantly increased MCP dispersal rate |
| 6 | Direct via human contact, hospital | Buttner, 2001, USA [17] | Exp. | Experimental hospital room (36 surface samples) | Dispersal of Penicillium chrysogenum spores by walking over carpet and vinyl floors | Aerosolized floor microorganisms | P. chrysogenum spores | Airborne contamination | Walking caused similar spore concentration at ground level up to breathing zone |
| 7 | Direct via human contact, hospital | Gwaltney, 1982, USA [18] | Exp. | Hospital simulation room (36 recipients) | Transfer of rhinovirus- contaminated floor tiles to recipients | Floor tile contamination ± antiviral spray | Rhinovirus | Direct human infection | Higher infection rate uncleaned (56%) vs. cleaned (36%) tiles |
| 8 | Direct via human contact, non-hospital | Wright, 1968, USA [19] | Obs. | Naval vessels (2) | Microbiological contamination of naval ships | Aerosolized floor microorganisms | Saprophytic bacteria | Airborne contamination | Increased contamination with person traffic |
| 1 | Direct via aerosolization, hospital | Roberts, 2008, UK [20] | Obs. | Hospital (6-bed elderly care unit) and 4-bedded orthopedic bay (control) | Dispersal of C. difficile spores in patient rooms | Aerosolized C. difficile from the hospital environment | C. difficile spores | Airborne or surface culture | Aerosolization of C. difficile present in all 23 air samples during the first sampling phase and in none in second sampling phase |
| 2 | Direct via aerosolization, hospital | Hambraeus, 1978, Sweden | Exp. | Operation theatre (movement of 4 persons) | Dispersal of S. aureus bacteria via walking, wind currents, and mopping | Floor contamination | S. aureus | Surface | Bacteria most widely dispersed by walking followed by increased ventilation and mopping |
| 3 | Direct via aerosolization, community | Hospodsky, 2012, USA [22] | Obs. | University classroom | Dispersal of bacterial genome from classroom floor dust | Aerosolized floor dust microorganisms | Bacterial genome copy numbers | Airborne contamination | Human movement was significantly associated with aerosolization of floor dust microorganisms |
| 4 | Direct via aerosolization, community | Lues, 2006, South Africa [24] | Obs. | Retail outlet | Dispersal of HAI bacteria from randomly selected delicatessens | Aerosolized bacteria from delicatessens | S. aureus and Enterobacteriaceae | Airborne | Aerosolized bacteria present in majority of outlets, increased with number of customers |
| 5 | Direct via aerosolization, community | Weis, 2002, USA [28] | Obs. | Office suite | Dispersal of Bacillus anthracis spores from floor dust based on human activity | Aerosolized Bacillus from office environment | B. anthracis spores | Airborne | All spores aerosolized within 10 min. Aerosolization rate increased with human activity |
| 6 | Direct via aerosolization, community | Hsing, 2002, USA [23] | Obs. | Office building | Dispersal of fungal spores from floor dust to office chairs | Aerosolized fungal spores from floor dust | Fungal spores | Surface | Increased chair contamination with increased fungal spore dust concentrations |
| 7 | Direct via aerosolization, animal worker | O'Connor, 2015, Australia [21] | Obs. | Sheep yard (25 infected sheep and 45 controls from another yard) | Sheep yard with Q fever infected sheep and controls from another yard | Aerosolized ground microorganisms | Coxiella burnetti | Airborne contamination | Exposure to contaminated sheet yard increased risk of Q fever [OR 15·3 (P = 0·014)] |
| 8 | Direct via aerosolization, animal worker | Brodka, 2012, Poland [25] | Obs. | Poultry house | Dispersal of microorganisms at poultry house to at least 1·5 m | Aerosolized ground microorganisms | HAI bacteria | Airborne contamination | All samples were positive for microorganisms at 1·5 m |
| 9 | Direct via aerosolization, laboratory | Paton, 2015, UK [44] | Exp. | Laboratory setting | Dispersal of spores by human walking over carpet and PVC flooring | Aerosolized Bacillus from office environment | B. anthracis | Airborne | Type of flooring (carpet > PVC) and increased pace of walking increased airborne contamination |
| 10 | Direct via aerosolization, laboratory | Rafal, 2002, USA [26] | Exp. | Aerosolization chamber | Dispersal of fungal spores from floor to ceiling plate | Aerosolization of fungal spores | Fungal spores and fragments | Airborne | Aerosolization increased based on fungal species, quantity, air velocity, and surface vibration |
| 11 | Direct via aerosolization, laboratory | Rafal, 2003, USA [27] | Exp. | Aerosolization chamber | Dispersal of Streptomyces albus from floor to ceiling plate | Aerosolization of Bacterial spores | S. albus spores | Airborne | Aerosolization rate increases with increased air velocity, type and roughness of surface |
| 1 | Indirect via arthropods | Aquino, 2011, Brazil [29] | Obs. | Public hospital (n = 1) | Pathogenic soil-borne fungus isolated from ants in hospitals | Ants | Fungal spore | Surface | Pathogenic fungi isolated from 40% of ants |
| 2 | Indirect via arthropods | Hsiu-Hua Pai, 2004, Taiwan [31] |
Obs. | Acute care hospitals (n = 90) | Cockroaches cultured for presence of HAI microorganisms | Cockroaches | HAI pathogens | Surface | All cockroaches harboured bacteria with resistance to at least one antibiotic |
| 3 | Indirect via arthropods | Fotedar, 1993, India [32] | Obs. | Surgical ward of hospital | Cockroaches from surgical ward cultured for HAI organisms | Cockroaches | HAI pathogens | Surface | Almost all (>90%) cockroaches had HAI pathogens |
| 4 | Indirect via arthropods | Sramova, 1991, Czechoslovakia [30] | Obs. | Healthcare facilities (n = 55) | Arthropods cultured for HAI pathogens | Arthropods* | HAI pathogens | Surface | Contamination rate: 13–59%. Higher rates with increased arthropod mobility |
| 5 | Indirect via arthropods | Sola-Gines, 2015, Spain [33] | Obs. | Chicken broiler farms (n = 5) | Flies cultured for ESBL E. coli | Flies | Cephalosporin-resistant E. coli | Surface | 42 of 682 (6·2%) flies contaminated |
| 1 | Indirect, other mechanisms | Jonges, 2015, Netherlands [45] | Obs. | Poultry farms | Particulate matter or inhalable dust particles around poultry farms | Wind-mediated dispersal | Avian Influenza Virus | Surface | Influenza virus detected up to 60 m downwind from the barn |
| 2 | Indirect, other mechanisms | Monaghan, 2012, UK [36] |
Obs. | Community | E. coli marker bacteria inoculated in irrigation water | Soil splash | E. coli | Surface | Irrigation water splash disperse bacteria at least 25 cm horizontally 20 cm high |
| 3 | Indirect, other mechanisms | Nieuwenhuijsen, 1999, USA [37] | Obs. | Farms (n = 10) | Workers tested for inhalable and respirable endotoxin concentration | Aerosolization and inhalation of endotoxin via farm activities | Dust and bacterial endotoxin | Aerosolization | Cleaning of poultry houses associated with highest levels of endotoxin |
| 4 | Indirect, other mechanisms | Gagniere, 2006, France [35] |
Exp. | Food plant | High-pressure water cleaning of surfaces of food industry | High-pressure aerosolization | Pseudomonas putida | Surface | P. putida adherence to high-pressure water pipe. |
| 5 | Indirect, other mechanisms | DiCaprio, 2015, USA [34] | Exp. | Farm soil | Strawberry plants cultured after planting in virus-contaminated soil | Contaminated soil | Murine norovirus-1 (MNV-1) and Tulane virus (TV) | Surface | Virus present on 33% of strawberries |
| 6 | Indirect, other mechanisms | Penet, 2014, France [38] | Exp. | Community | Dispersal of fungal spores by rain splash | Rain splash dispersal | Colletotrichum gloeosporioides | Surface | Direct splashing contributed to dispersal of fungal spores |
Obs., Observational; Exp, experimental; HAI, healthcare-associated infection; OR, odds ratio; MCP, microbe-containing particle; ESBL, extended-spectrum beta-lactamase.
* Arthropods included cockroaches, ants, and other insects.