Acid-base variables in acute and chronic form of nontuberculous mycobacterial infection in growing goats experimentally inoculated with Mycobacterium avium subsp. hominissuis or Mycobacterium avium subsp. paratuberculosis

Abstract

In current literature, data assessing the acid-base equilibrium in animals and humans during bacterial infection are rare. This study aimed to evaluate acid-base deteriorations in growing goats with experimentally induced NTM (nontuberculous mycobacteria) infections by application of the traditional Henderson-Hasselbalch approach and the strong ion model. NTM-challenged animals were orally inoculated with eitherMycobacterium aviumsubsp.hominissuis(MAH; n = 18) orMycobacterium aviumsubsp.paratuberculosis(MAP; n = 48). Twenty-five goats served as non-infected controls. Until 51stweek post-inoculation (wpi), blood gas analysis, serum biochemical analysis, and serum electrophoresis were performed on venous blood. Fifty percent (9/18) of goats inoculated with MAH developed acute clinical signs like apathy, fever, and diarrhea. Those animals died or had to be euthanized within 11 weeks post-inoculation. This acute form of NTM-infection was characterized by significantly lower concentrations of sodium, calcium, albumin, and total protein, as well as significantly higher concentrations of gamma globulin, associated with reduced albumin/globulin ratio. Acid-base status indicated alkalosis, but normal base excess and HCO3-concentrations, besides significantly reduced levels of SID (strong ion difference), Atot Alb(total plasma concentration of weak non-volatile acids, based on albumin), Atot TP(Atotbased on total protein) and markedly lower SIG (strong ion gap). The remaining fifty percent (9/18) of MAH-infected goats and all goats challenged with MAP survived and presented a more sub-clinical, chronic form of infection mainly characterized by changes in serum protein profiles. With the progression of the disease, concentrations of gamma globulin, and total protein increased while albumin remained lower compared to controls. Consequently, significantly reduced albumin/globulin ratio and lower Atot Albas well as higher Atot TPwere observed. Changes were fully compensated with no effect on blood pH. Only the strong ion variables differentiated alterations in acid-base equilibrium during acute and chronic NTM-infection.