Detection of SARS-CoV-2 within the healthcare environment: a multi-centre study conducted during the first wave of the COVID-19 outbreak in England

BACKGROUND

Understanding how severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is spread within the hospital setting is essential in order to protect staff, implement effective infection control measures, and prevent nosocomial transmission.

METHODS

The presence of SARS-CoV-2 in the air and on environmental surfaces around hospitalized patients, with and without respiratory symptoms, was investigated. Environmental sampling was undertaken within eight hospitals in England during the first wave of the coronavirus disease 2019 outbreak. Samples were analysed using reverse transcription polymerase chain reaction (PCR) and virus isolation assays.

FINDINGS

SARS-CoV-2 RNA was detected on 30 (8.9%) of 336 environmental surfaces. Cycle threshold values ranged from 28.8 to 39.1, equating to 2.2 x 105 to 59 genomic copies/swab. Concomitant bacterial counts were low, suggesting that the cleaning performed by nursing and domestic staff across all eight hospitals was effective. SARS-CoV-2 RNA was detected in four of 55 air samples taken <1 m from four different patients. In all cases, the concentration of viral RNA was low and ranged from <10 to 460 genomic copies/m3 air. Infectious virus was not recovered from any of the PCR-positive samples analysed.

CONCLUSIONS

Effective cleaning can reduce the risk of fomite (contact) transmission, but some surface types may facilitate the survival, persistence and/or dispersal of SARS-CoV-2. The presence of low or undetectable concentrations of viral RNA in the air supports current guidance on the use of specific personal protective equipment for aerosol-generating and non-aerosol-generating procedures.

Quantitative assessment of interactions between hospitalized patients and portable medical equipment and other fomites

In an observational study, we demonstrated that hospitalized patients frequently had direct or indirect interactions with medical equipment and other fomites that are shared among patients, and these items were often contaminated with health care-associated pathogens. There is a need for protocols to ensure routine cleaning of shared portable equipment.

Bacterial colonization of respiratory therapists' pens in the intensive care unit

BACKGROUND

Prevention of nosocomial infections is of paramount importance. Person-to-person transmission of microorganisms is well recognized, but the role of fomites in nosocomial infection is not as well understood. Incomplete cleaning of equipment and patient rooms, and medical devices used with multiple patients are well-described means of transmission, but little attention has been paid to nonmedical devices as fomites. We collected bacteria from writing implements (pens) used by respiratory therapists in an intensive care unit, following their work shifts.

METHODS

We obtained pens from 20 respiratory therapists, and cultured, enumerated, and identified the bacteria.

RESULTS

Bacteria were found on 17 of the 20 pens. The mean +/- SD number of colony-forming units was 126 +/- 277 (range 0-1,250). Coagulase-negative staphylococci were found on all 17 pens. Micrococcus species were found on 4 pens.

CONCLUSIONS

Although we found no organisms that are regularly associated with nosocomial infections (eg, methicillin-resistant Staphylococcus aureus or Gram-negative bacilli), pens can be fomites responsible for nosocomial infections. Protocols to reduce the transmission of infectious agents may need to be extended to writing instruments. One possible measure is to assign specific writing instruments to specific rooms.

Flies, fingers, fomites, and food. Campylobacteriosis in New Zealand--food-associated rather than food-borne

AIMS

New Zealand has a very high rate of seasonal, sporadic campylobacteriosis compared to other OECD countries. Can the seasonality of New Zealand cases fit with an explanation of food-borne transmission (especially by chicken meat), and where does the fly-transmission hypothesis fit?

METHODS

Analysis of seasonal campylobacteriosis reports at the District Health Board level compared to regional ambient temperatures, and chicken consumption data. Literature review particularly of food-associated disease risks and transmission routes.

RESULTS

Campylobacteriosis rates in New Zealand show a national annual increase at a rate similar to chicken consumption. A drastic reduction in chicken consumption was associated with significantly reduced campylobacteriosis cases in two European countries, further strengthening the link between disease risk and chicken consumption. However, serotype analysis of the Campylobacter isolates is ambiguous regarding chicken meat itself as the major source of infection. The seasonal colonisation pattern in live chickens follows the seasonal increase in human cases. Flies are a plausible vector, associated with increasing overwintered fly foraging activity, rather than a summer increase in fly numbers.

CONCLUSION

The typically sporadic rather than outbreak nature of campylobacteriosis, the disjoint between seasonal patterns of human and chicken infection, the seasonal pattern itself, and inconclusive serotype evidence indicates against chicken meat itself as the major source of infection. However, chicken consumption is a significant risk factor.