All 43 studies presented an assessment of chosen technology on HAI rates, which described the effect on one specific pathogen or a combination; from
Clostridium difficile, methicillin-resistant
Staphylococcus aureus (MRSA), multi-drug resistant Gram-negative coliforms (MDRGN), multi-drug resistant Acinetobacter (MDRA),
Pseudomonas aeruginosa, vancomycin-resistant enterococci (VRE), combined multiply drug resistant organisms (MDROs); or overall HAI rates; or surgical site, catheter and device infection rates (Table
1). The most popular pathogen to control with automated devices, either alone, or in combination with others, was
C. difficile (27 of 43 studies: 63%), followed by MRSA (16 of 43: 37%); MDRA (15 of 43: 35%); VRE (14 of 43: 33%) and MDRGN (12 of 43: 28%). There were 29 of 43 studies (67%) that also performed before and after sampling of the environment for the same pathogens as monitored for patient infections.
Most studies reported either reductions in HAI rates for the study pathogen(s) or resolution of an outbreak. Some studies reported effects on one or more pathogen rates along with no change or even increases in other pathogen rates. Two studies reported an increase in
C.difficile rates using UV and H2O2 [
18,
32] and another reported static rates for
C. difficile and VRE following UV use in a bone marrow transplant unit [
23]. One analysis of the BETR study (using UV) saw a reduction only in VRE and not in rates of infection due to
C. difficile, MRSA or Acinetobacter, although the latter numbers were so small, the effect could not be analysed [
24]. Other
C. difficile studies using UV showed no statistically significant decrease over a 25 month period, [
28] while at the same time rates decreased for the bone marrow transplant unit in the same hospital; [
16] another UV study reported a decline in
C. difficile but not for other pathogens including MRSA [
31]. Mixed results for UV were also found by Vianna et al., with reductions in
C. difficile and VRE in the study ICU but increasing MRSA and static VRE rates outside the ICU [
35]. One study using UV on a burn unit found no significant impact on total MDRO, device-associated infections or MDRGNs [
34]. One study targeted operating theatres and measured the impact of UV on surgical site infection rates; these decreased for ‘clean’ but not for ‘clean contaminated’ surgery, which actually increased by 23% [
36]. Several studies saw non-significant effects on MRSA using both H2O2 [
38,
47] and UV [
39], and another UV study achieved a reduction in
C. difficile rates only after introducing a supervised cleaning team targeting hand-touch sites with bleach wipes [
50]. One protracted outbreak of MDRA reoccurred despite hydrogen peroxide and additional infection control interventions [
45] and another recovered the outbreak MDRA from the environment 2–3 weeks after hydrogen peroxide treatment [
55].