Human skeletal muscle in bacterial infection: enzyme activities and their relationship to age.

8 male patients (age 65-82 years) suffering from bacterial pneumonia or erysipelas were subjected to skeletal muscle biopsies. Significantly lower activities of lactate dehydrogenase (LDH) and glyceraldehyde-3-phosphate dehydrogenase (TPD) of skeletal muscle were recorded in the acute phase of the illness as compared to after the end of the convalescent phase. For citrate synthetase (CS) a similar although non-significant tendency was observed, while cytochrome c oxidase (CYTOX) was not altered by infection. Similar results have been reported in young patients with viral and mycoplasma infections. In the old patients the activity of LDH was approximately half of that found in the young patients (and in young controls confined to bed) on all occasions of measurement.