Health and safety | PPC96 August 2019
More than 50% of bacteria recovered from flying insects in a group of English hospitals were resistant to one or more antibiotics, posing a potential infection risk to patients, according to a new study.
SPEED VIEW
- Study finds 90% of insects analysed from seven hospitals carried potentially harmful bacteria – over 50% were antibiotic-resistant
- ‘Bugs with bugs’ were collected from food prep areas and wards including neonatal and maternity
- Findings underline importance of pest control measures in healthcare environments to prevent public health risk to patients
- Study was co-authored by Dr Matthew Davies of BPCA member Killgerm Chemicals.
The Aston University study collected almost 20,000 insect samples over an 18-month period – including houseflies, ‘filth flies’ such as bluebottles and greenbottles and a variety of ’drain flies’ – from seven NHS hospital sites in England.
The analysis found that nearly nine in 10 of those tested were carrying potentially harmful bacteria such as E.coli, Salmonella and Staphylococcus aureus.
A total of 86 bacterial strains were isolated from the insect samples.
In some cases, the level of bacteria carried by flying insects was enough to potentially cause infection.
Multi-drug resistance
Flying insects harbouring bacteria were collected from a number of locations throughout the hospitals using ultraviolet (UV) light flytraps, electronic fly killers and sticky traps.
They included areas where food for patients, visitors and staff were prepared or stored, as well as wards, neonatal units and maternity units.
Over 75% of the insects collected were ‘true flies’ – a group which includes midges and common houseflies – with a further 14% being ‘true bugs’, including aphids.
Smaller groups of ants, wasps, bees and moths were also collected.
The results from this large-scale microbiological analysis show that a variety of flying insects collected from UK hospitals do indeed harbour pathogenic bacteria of different species.
The analysis showed that 53% of the strains were resistant to one or more class of antibiotics.
Of this figure, 19% were resistant to multiple antibiotics, a feature known as multi-drug resistance (MDR).
Penicillin was found to be the least effective antibiotic, with many bacteria showing resistance.
Resistance to other commonly-administered antibiotics, including vancomycin and levofloxacin, was also observed.
Pest management and infection control
The study, published in the Journal of Medical Entomology, was co-authored by PhD student Federica Boiocchi, and Professor Anthony Hilton, both from Aston University’s School of Life and Health Sciences and Dr Matthew Davies of Killgerm Chemicals.
Lead author, Federica Boiocchi, said: “The results from this large-scale microbiological analysis show that a variety of flying insects collected from UK hospitals do indeed harbour pathogenic bacteria of different species.
“What’s quite interesting, though, is the high proportion of drug-resistant bacteria found in these samples.
It’s a vivid reminder of how our overuse of antibiotics in healthcare settings is making infections more difficult to treat.”
Anthony Hilton, Professor of Applied Microbiology at Aston University, added: “NHS hospitals are extremely clean environments and the risk of insects carrying bacteria and transferring these to patients is very low.
“What we are saying in this paper is that even in the cleanest of environments, it’s important to take steps to prevent bacteria being brought into hospitals by insects.
“NHS hospitals will already be implementing many of these measures, but there are simple steps that can be taken to improve this further.
“Infection control is taken extremely seriously in the NHS. Insects will only play a very small role in the transfer of bacteria, so this risk should be seen in the context of wider efforts to stop the spread of harmful and drug-resistant bacteria.”
Dr Matthew Davies, of Killgerm Chemicals, said: “We hope this study is useful for those in charge of pest management measures, for example by highlighting when insects are likely to be most prevalent and which are of the greatest risk to public health.
“This knowledge then informs the selection and installation of quality insect monitors and effective UV light traps, among other integrated pest management measures provided by professionals.
“It could also mean emphasising the importance of replacing glue boards and UV-tubes more frequently, and monitoring the insect catch closely, especially during the warmer months.”
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Source: PPC96