This article is more than 5 years old. Information may no longer be current.
Higher bacterial burden increases E. coli transmission odds
Click Here to Manage Email Alerts
As Escherichia coli bacterial counts increased on one health care worker’s hand, so did the extent of transmission to another in a recent study.
The results of the study conducted at the University of Geneva Hospitals in Switzerland were published in the journal Infection Control and Hospital Epidemiology. The researchers say they may offer a transmission threshold leading to more effective hand sanitation among health care workers.
“Under the described experimental conditions, at least 1 log10 [colony-forming unit (cfu)] of E. coli must be present on hands to be potentially transmitted to another person,” they wrote.
“This threshold may be useful for the development of an evidence-based ‘safe hands’ microbiological concept that can be applied in the health care setting, as well as in the community, to prevent the spread of infections and antimicrobial resistance.”
The study included three health care worker pairs, each consisting of a transmitter and a host. The pairs performed 30 experiments in four separate trials using increasing amounts of E. coli bacteria.
The bacteria increased with each trial, from 103 cfu/mL in the first to 106 cfu/mL in the fourth.
In each trial, the transmitter submerged the fingers of both hands, to the midcarpals, into a suspension containing E. coli . The transmitter then interlocked his or her right hand with that of the host for 1 minute.
During that time, the transmitter’s unlocked left hand was sampled for bacteria. After a minute had expired, the host’s right hand was sampled.
The researchers noted that, by employing unrealistically long hand-holding, they sought to “account for the repeated hand-to-skin brief contacts between a [health care worker] and a patient ...”
They also wanted to maximize the opportunity for transmission to yield conservative estimates, they added.
The researchers found that hand-to-hand transmission of E. coli was 8.22 times more likely when the bacterial count on the transmitter hand was greater than 1 and 3 log10 or less. The OR increased to 212.6 when the bacterial count was greater than 4 log10.
The researchers noted that further studies on disease transmission are needed.
“Our findings need to be further explored and confirmed by studies specifically addressing low concentration ranges, as well as other potential pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus spp., fungi or viruses,” they wrote.
“Should future studies show equivalent results to those presented here, 1 log10 cfu could be considered as a microbiological endpoint for the development and regulation of products intended to be used for hand hygiene in healthcare.” – by Joe Green
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts