Bacteria hitch an ambulance ride

The average British ambulance is hardly what you'd call spacious, with an interior volume measuring about 12 cubic meters. But the cramped conditions offer plenty of room for unwanted microbes to ride along, a presentation at the UK Ambulance Service Association's annual conference showed recently.At the meeting, held early last month, representatives from Steris Industrial Decontamination described what they found between November 2004 and April 2005 when they repeatedly examined the vehicles of 12 unnamed ambulance services in England, Scotland, Ireland, and Wales. They swabbed inside the ambulances immediately after a routine cleaning with a variety of disinfectants, and after disinfection with the company's vaporized hydrogen peroxide system following a 12-hour shift. They focused their attention on eight sites within the vehicle, including the rails of a stretcher, the track beneath the stretcher, an overhead locker and the paramedic's utility bag.The results were not comforting for anyone planning – or not planning – to ride in an ambulance. "We found that the ambulances were very heavily contaminated with a variety of organisms," says Gerald McDonnell, senior director, technical affairs, for Steris. "What I was very surprised at was how consistent the data were."In a typical vehicle, four out of eight swabs prior to cleaning gathered a mixed population with more colony forming units than it was possible to count. The range of organisms included methicillin-resistant Staphylococcus aureus, Bacillus cereus, other staphylococci, and various coliforms.After normal cleaning procedures, there was little evidence that things were any better, he notes. "In each case, the levels of bacteria were almost identical. They were probably shifting around the contamination... the surfaces may have looked clean, but they were not disinfected." After fumigation with the company's hydrogen peroxide system, however, the study team did record a difference – they could find almost no evidence of contamination. "That was a bit of a surprise to me," McDonnell says. "We weren't trying to sterilize the ambulances, but it was encouraging to reach such low levels."Now, it doesn't hurt a disinfectant company's prospects to find lots of bacteria on a surface they'd like to be paid to clean. Still, the findings jibe with the results of another study reported in 2003. In that investigation of Welsh ambulances, Yamni Nigam from the School of Health Science at the University of Wales, Swansea, and Jayne Cutter, an infection control nurse from Singleton Hospital, found that most sites within emergency vehicles were widely contaminated before cleaning – and that after cleaning, many sites were still contaminated. In fact, "some sites that were previously uncontaminated became freshly contaminated as a result of the cleaning methods used," they wrote in the Emergency Medicine Journal.That earlier paper had caused something of a stir in Wales when first published. Tipped off to the study by a press release from the journal's publishers – the BMJ Publishing Group – at least one local paper ran the story with characteristic British newspaper gusto. "Dirty ambulances infested with huge amounts of harmful bacteria are carrying seriously ill patients to hospital in Wales," ran the headline in The Western Mail.The resulting public concern prompted Mike Simmons, senior medical officer for communicable diseases in the Welsh Assembly government, to write a scathing letter to the journal stating that the authors "totally fail to present evidence to justify the claim that 'Welsh emergency vehicles examined exhibited an unacceptable level of bacterial contamination.' The authors make no attempt to quantify levels of bacteria for organisms that are expected to be present in an environment occupied by people.... The only potential pathogen identified by the study is Staphylococcus aureus."Simmons hasn't seen the details of the latest study, but says that by referring to the findings of Nigam and Cutter, the authors might be building their argument on a somewhat flimsy foundation. "This is a common failing," Simmons says. "You can take swabs like this to look for the presence or absence of organisms, but you shouldn't use them to make claims about levels of contamination."In any case, in the healthcare setting, the biggest problem related to infection control is hand hygiene, Simmons adds. "If hand hygiene is good, then any bacteria acquired from the environment will be removed prior to any patient contact."But McDonnell explains that there are two schools of thought on contamination. "Some people will say that hand washing is the most important, while others will say the data is more suspect," he says. "What I take from it is that hand washing is important, but so is an understanding of where infection comes from and how to interrupt the chain of infection."

Bacteria hitch an ambulance ride

The average British ambulance is hardly what you'd call spacious, with an interior volume measuring about 12 cubic meters.

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