Microbiologists
have found that many washing machines in hospital setting as are reservoirs of
multidrug-resistant bacteria. In one case study pathogens, were transmitted regularly
to newborns in a neonatal intensive care unit at a children's hospital.
Microbiologists,
as
reported by the American Society for Microbiology, have
demonstrated how resistance
genes,
as well as many water-borne microorganisms, can persist in domestic washing
machines at reduced temperatures.
Klebsiella
oxytoca
is a Gram-negative, rod-shaped bacterium that is closely related to K.
pneumoniae. Outbreaks of antibiotic-resistant Klebsiella oxytoca have occurred
in multiple hospitals and ICUs throughout the world
With
the hospital case study, standard screening protocols demonstrated the presence
of the Klebsiella organism on infants in the ICU. Genetic comparative testing
traced the source of the bacterium to the washing machine. In the course of the
investigation, both incubators (used for babies born prematurely) and
healthcare workers were ruled out as the sources of the contamination.
It
appears that clothes, like knitted caps and socks, and blankets washed in the
machine transmitted K. oxytoca from
the washer to the infants. The residual water on the rubber mantle of the
washer together with the final rinsing process (where unheated water is used)
were found to contain the contaminant.
The
infants in the intensive care units (ICU) were colonized, but not infected by K. oxytoca. However, the potential for a
serious public health risk exists unless action is taken.
The
research also carries implications for household washers, as well as those
located in hospitals. This may relate to factors associated with energy
management and environmental concerns. The water temperatures used in many
domestic washing machines have been declining, ostensibly to save energy (and
money). This was driven temperatures to regularly to be below 60°C (140°F). At
such temperatures the water is less effective in terms of killing vegetative
bacteria.
The
study recommended that changes in washing machine design and processing are needed
in order to prevent the accumulation of residual water leading to conditions
favourable for microbial growth.
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
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