Air dispersal of multi-drug-resistant organisms including meticillin-resistant Staphylococcus aureus, carbapenem-resistant Acinetobacter baumannii and carbapenemase-producing Enterobacterales in general wards: surveillance culture of air grilles.

BACKGROUND: The environmental surveillance of air grilles in clinical areas has not been systematically analysed. METHODS: Samples were collected from frequently touched items (N = 529), air supply (N = 295) and exhaust (N = 184) grilles in six medical and 11 surgical wards for the cultures of multi-drug-resistant organisms (MDROs): meticillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenemase-producing Enterobacterales (CPE), and isolates were selected for whole-genome sequencing (WGS). The contamination rates were correlated with the colonization pressures of the respective MDROs. RESULTS: From 3rd October to 21st November 2023, 9.8% (99/1008) of the samples tested positive, with MRSA (24.2%, 24/99), CRAB (59.6%, 59/99) and CPE (2.0%, 2/99), being the only detected MDROs. The contamination rate in air exhaust grilles (26.6%, 49/184) was significantly higher than in air supply grilles (5.8%, 17/295; P<0.001). The contamination rate of air exhaust grilles with any MDRO in acute medical wards (73.7%, 14/19) was significantly higher than in surgical wards (12.5%, 4/32; P<0.001). However, there was no difference in the contamination rate of air exhaust grilles between those located inside and outside the cohort cubicles for MDROs (27.1%, 13/48 vs 28.8%, 30/104; P=0.823). Nevertheless, the weekly CRAB colonization pressure showed a significant correlation with the overall environmental contamination rate (r = 0.878; 95% confidence interval (CI): 0.136-0.986; P=0.004), as well as with the contamination rate in air supply grilles (r = 0.960; 95% CI: 0.375-0.999; P<0.001) and air exhaust grilles (r = 0.850; 95% CI: 0.401-0.980; P=0.008). WGS demonstrated clonal relatedness of isolates collected from patients and air exhaust grilles. CONCLUSIONS: Air grilles may serve as MDRO reservoirs. Cohort nursing in open cubicles may not completely prevent MDRO transmission through air dispersal, prompting the consideration of future hospital design.

Vitamin B12 deficiency in the institutionalized elderly: A regional study.

The prevalence of vitamin B12 deficiency increases with age and is suggested to be even higher in the elderly living in institutions. This retrospective study evaluated the vitamin B12 and folate status of 1996 institutionalized elderly residents aged over 65years. Among them, 34.9% had vitamin B12 deficiency (serum vitamin B12 <150pmol/L), 11.8% had folate deficiency (serum folate <6.8nmol/L), and 4.9% had both. The majority of vitamin B12 deficient residents (68%) had serum vitamin B12 between 100pmol/L and 149pmol/L. Macrocytosis was found in 24.2% of vitamin B12 deficient residents. A significant increase in macrocytosis was associated with a decrease in serum vitamin B12 below 100pmol/L. Macrocytosis was most common in those with vitamin B12 ≦69pmol/L (50.9%). Overall, vitamin B12 deficiency is common in the institutionalized elderly, however macrocytosis cannot predict deficiency. More liberal testing for vitamin B12 status in the institutionalized elderly may be warranted.