Doctors in Istanbul had been mystified as to how the Acinetobacter strain was making its way around hospital wards.
A visiting infection control team from Linz in Austria had looked at all the usual potential sources - such as poor hygiene among medical staff or orderlies - but found nothing.
However, when they looked at the flasks used to carry tea and other hot drinks, they found that more than half of them carried significant numbers of the dangerous organism.
Rubber trouble
They found that rubber seals in the flasks had perished over time, making them impossible to sterilise once contaminated.
Liquid collected between the inner and outer walls of the flask formed a reservoir for the infection.
A wider examination of 56 flasks in three hospitals found 26 were riddled with potentially harmful bacteria.
This case was presented to the European Society of Clinical Microbiology and Infectious Disease in Istanbul on Tuesday.
Other delegates told the conference how they were experiencing problems with the same type of bacteria, which now appears to have become resistant to the vast majority of antibiotics.
Many said that problems with resistant bugs could often be traced to the water supply in the hospital.
Legionnaire's disease
One major problem in European hospitals is legionnaire's disease, which can be caused by bacteria lurking in air-conditioning systems or water tanks.
More than 2,100 cases were reported in Europe in 1999 against only 1,360 in 1997.
In the UK, the House of Commons public accounts committee says up to 5,000 patients die from a hospital-acquired infection every year, costing the NHS £1bn.
And in a poll of more than 800 doctors, eight out of 10 said hygiene rules were "commonly broken" in hospitals.
Three quarters believed poor infection controls were putting lives at risk unnecessarily.
In January, the government ordered hospitals to improve standards of cleanliness by this month or face inspections by the Commission for Health Improvement.