There are already resistant bacteria to two of three of the latest generation of antibiotics marketed for treatment of pneumonia in cattle, according to a study by Schering Plough Animal Health.

The company’s senior brand manager, Stewart Hall, says resistance problems with older antibiotics, such as tetracycline, have been known for some time.

And, as with sheep wormers, bacteria are likely to develop resistance to antibiotics over time.

This large-scale EU trial, commissioned by Schering Plough, looked at the three main bacterial pneumonia causes and three new generation antibiotics.

For two of these pneumonia causes, P multocida and H somni, there is no vaccine available, so producers must rely on antibiotics to treat such cases, says Schering Plough vet Andrew Montgomery.

“But it is important to recognise an antibiotic can fail because of resistant bacteria, even when a product has been chosen for the agent causing the disease on the farm.

“For one of the bacterial causes studied, H somni involved in one in five UK bacterial pneumonia cases last year, more than 70% of the 99 strains tested showed some resistance to one of the antibiotics.

More than a quarter of the 99 strains also showed some resistance to a second antibiotic.”

But no resistance problems in the three bacteria were found with florfenicol, the active ingredient in Schering Plough’s Nuflor antibiotic, he added.

He advises producers to continually review their pneumonia treatment protocols with the vet, considering the history of outbreaks, diagnostic data which identifies bacteria or viruses present and the success of previous treatment regimes.

It is also essential to act early to prevent permanent lung damage, says Mr Hall.

“Lung damage will reduce growth rates and feed conversion efficiency.”