The recently published figures for the hospital bug Clostridium difficile (C. diff) were encouraging. Across Scotland the number of cases of the infection in the most vulnerable age-group - the over 65s - was down by 38% in the first three months of this year, on the same period last year. A major effort and investment by the Scottish Government appears to be paying off, following the shocking outbreak at the Vale of Leven Hospital in which 18 people died in 2008. Health secretary Nicola Sturgeon rightly describes the scourge of hospital-acquired infections (HAIs) as the most challenging issue she has faced.

Between 2000 and 2007, the annual number of deaths in which C. diff appeared on a death certificate as either the underlying cause or a contributory factor increased alarmingly from 116 to 597. The 2008 figures, due out next week, are likely to be bleak. The Herald has learned that in one hospital alone, Gartnaval General Hospital in Glasgow, 38 died from the condition in the two years to last December. The 2008 figure - 18 - is similar to the previous year, when 20 died, and is comparable with the Vale of Leven, where over six months C. diff was the main underlying cause in half of the 18 deaths in an outbreak that attracted massive publicity.

Worryingly, in another Gartnavel case, brought to the attention of Maryhill MSP Patricia Ferguson, C. diff was not mentioned on the death certificate, even though it had been diagnosed and contributed to the death of her constituent. Inevitably, this raises the question of whether these figures give the full picture, especially at a time when both health boards and individual hospitals are under intense pressure from the Scottish Government to reduce them.

The deceased's family received an assurance from NHS Greater Glasgow and Clyde that hospital doctors would be reminded to record C. diff on certificates, even if it was only a contributory cause of death. Is this practice being rigorously applied in every health board area? If not, mortality figures are not giving accurate comparisons between one hospital or one area and another. This is important when such data is used to inform good (and poor) practice.

Following the Vale of Leven outbreak, the Scottish Government subscribed to a policy of transparency, publishing HAI figures for every hospital in an accessible format. This effectively recruits the public in the battle against superbugs and brings a harsh spotlight to bear on those failing to tackle these infections effectively. The new Healthcare Environment Inspectorate will be making random checks to ensure that infection control procedures are being followed and senior officials could be sacked if standards of cleanliness are not met. All this puts extra pressure on hospital administrators and increases the importance of properly recording data.

This is a vitally important issue. It represents a betrayal of public confidence in the NHS when those who go to hospital in the hope of better health, sicken and sometimes die as a result of an infection acquired as a hospital patient.