Mycobacterium mucogenicum is a bacterium found in soil and water, and it caused an outbreak of bloodstream infections in four young people with sickle cell anaemia at a US University haematology outpatient clinic in 2008. Researchers from East Carolina University used the polymerase chain reaction (PCR) and genotyping to find the source of the outbreak, and the results were published in the journal Infection Control and Hospital Epidemiology.

tap or faucet with aerator

Source: Nicole Koehler (

There have been five other outbreaks of this infection since 1995 in hospitals in the US, Israel and Scotland in immunocompromised patients; this was the first case in an outpatient setting. The researchers used repetitive sequence-based polymerase chain reaction (PCR using primers that are complementary to repeated non-coding sequences in the genome) and genotyping analysis to identify bacteria from patients and bacteria in the environment. They were able to match the type of bacteria with the source with 98.5% similarity – water from a tap with an aerator in the examination room.

However, this wasn’t the end of the story – it’s not uncommon to find M mucogenicum in tap water in the US and elsewhere, so the team had to carry out a bit of detective work to find out how the bacteria was transmitted to the patients. Each patient had a long-term implanted port for the delivery of medication, and this was likely to be where the infection entered.

After an audit of infection control procedures, including hand hygiene compliance and use of appropriate techniques for injections, the team found that one of the nurses prepared intravenous port flushes on the sink counter, using a bag of saline hanging over the sink. This probably became contaminated with water when she washed her hands.

Taps with aerators have been linked with previous outbreaks, and so the hospital removed all water aerators and reminded the members of staff that sinks should not be used as workspaces. Since these changes, there have been no further cases of M mucogenicum bloodstream infection. The patients had their implanted lines removed and were treated with antibiotics, and all have recovered.

“This study demonstrates the efficacy of using genotyping technology in identifying the source of the outbreak,” said Muhammad Salman Ashraf, MD, at East Carolina University. “But it also points to the need for proper infection control practice in clinic settings, and that faucet aerators should be avoided in all healthcare facilities, especially those caring for immunosuppressed patients.”

Suzanne Elvidge is a freelance science, biopharma, business and health writer with more than 20 years of experience. She is editor of Genome Engineering, a blog that monitors the latest developments in genome engineering and that aims to educate (and sometimes to entertain!) and has written for a range of online and print publications including FierceBiomarkers, FierceDrugDelivery, European Life Science, the Journal of Life Sciences (now the Burrill Report), In Vivo, Life Science Leader, Nature Biotechnology, PR Week and Start-Up. She specialises in writing on pharmaceuticals, biotechnology, healthcare, science, lifestyle and green living, but can write on any topic given enough tea and chocolate biscuits. She lives just beyond the neck end of nowhere in the Peak District with her second-hand bookseller husband and two second-hand cats.