Putative biomarkers for evaluating antibiotic treatment: an experimental model of porcine Actinobacillus pleuropneumoniae infection
Introduction
The outcome of antibiotic treatment of bacterial infections is traditionally evaluated by subjective clinical observations, e.g. combined in clinical score systems (Wallgren et al., 1999; Fodor et al., 2000). The clinical evaluation is often supported by more objective microbiological and pathological observations, especially in experimental studies. During the last decades, objective biochemical infection markers, e.g. the acute-phase protein C-reactive protein, have been extensively used as evaluators of the condition of human patients with acute infections (van Leeuwen and van Rijswijk, 1994). In contrast, objective biochemical markers of infection are not used routinely in veterinary medicine, although they might be a valuable supplement to the classically used methods of evaluation. To be usable for evaluation of antibacterial treatment of acute bacterial infection, an infection marker must respond rapidly and changes in the plasma concentration of the marker must parallel the development of the disease and reflect changes in the underlying pathology.
The objective of the present study was to evaluate objective biomarkers of infection for monitoring antibiotic treatment of bacterial infections, using an experimental model of acute Actinobacillus pleuropneumoniae (Ap)-infection in pigs. Thus, the changes in plasma concentration of biochemical infection markers, C-reactive protein (CRP), haptoglobin, interleukin-6 and zinc, were monitored during the course of the infection. Furthermore, plasma ascorbic acid and α-tocopherol were quantified as a measurement of the oxidative stress in the infected animals. To investigate the discriminative properties of the markers, the effect of the macrolide-like antibiotic tiamulin and the fluoroquinolone danofloxacin was compared, using dosage regimens expected to result in different therapeutic efficacy in favour of danofloxacin. The changes in the biochemical variables were subsequently compared with classic clinical, haematological and pathological observations.
Section snippets
Animals
Sixteen male, castrated pigs (Danish landrace × Yorkshire × Duroc) weighing from 28 to 38 kg were obtained from a herd, shown to be free of Ap and Mycoplasma hyopneumoniae by clinical and serological examination in accordance with the Danish SPF (specific pathogen free) surveillance system. The pigs were housed in individual pens in an isolated unit with a natural light schedule. The animals were fed twice daily with antibiotic-free commercial feed (Organica Promax, KFK, Præstø, Denmark, 1.12 Feed
Clinical and haematological observations
Within 20 h after challenge, the infected animals developed clinical and haematological signs of pneumonia with increased rectal temperature, respiratory rate and leukocyte number (WBC) (Figs. 1A–C). At this time-point, the infected animals received a single dose of either danofloxacin or tiamulin. Body temperature remained elevated in the tiamulin group (TG) throughout the experiment, while returning to the initial level in the danofloxacin group (DG) 24 h after treatment (Fig. 1A). Likewise,
Discussion
In recent years, the use of antibiotics has been the subject of much debate. In striving for a more rational use of antibiotics, well-validated and clinically relevant infection models provide a valuable tool for testing various antibiotics and dosage regimens. In the aerosol model used, the pigs were infected by voluntary inhalation of a relative low dose of bacteria, mimicking the natural infection with Ap. Ap is a common and severe cause of pleuropneumonia in pigs and comprises an important
References (48)
- et al.
Penetration of amoxycillin to the respiratory tract tissues and secretions in Actinobacillus pleuropneumoniae infected pigs
Research in Veterinary Science
(1998) - et al.
Alpha-tocopherol attenuates lung edema and lipid peroxidation caused by acute zymosan-induced peritonitis
Surgery
(1995) - et al.
The acute phase response of acid soluble glycoprotein, α1-acid glycoprotein, ceruloplasmin, haptoglobin and C-reactive protein in the pig
Veterinary Immunology and Immunopathology
(1996) - et al.
Efficacy evaluation of the use of oral tilmicosin in pneumonic calves
The Veterinary Journal
(2000) - et al.
Evaluation of various cytokines (IL-6, IFN-α, IFN-γ, TNF-α) as markers for acute bacterial infection in swine – a possible role for serum interleukin-6
Veterinary Immunology and Immunopathology
(1998) - et al.
The porcine acute phase response to infection with Actinobaccillus pleuropneumoniae. major acute phase protein and serum amyloid A are sensitive indicators of infection
Comparative Biochemistry and Physiology B
(1998) - et al.
Antioxidants: an integrative approach
Nutrition
(2001) - et al.
The pharmacodynamic effect of amoxycillin and danofloxacin against Actinobacillus pleuropneumoniae in an in vitro pharmacodynamic model
Research in Veterinary Science
(1999) - et al.
Growth of Escherichia coli in whole and skim milk from endotoxin-induced mastitic quarters: In vitro effects of dexoforamine, zinc and iron supplementation
Journal of Dairy Science
(1988) Determination of ascorbic acid and dehydroascorbic acid in biological samples by high-performance liquid chromatography using subtraction methods: reliable reduction with tris[2-carboxyethyl]phosphine hydrochloride
Analytical Biochemistry
(2000)
Ascorbate is depleted by smoking and repleted by moderate supplementation: a study in male smokers and non-smokers with matched dietary antioxidant intakes
American Journal of Clinical Nutrition
On the antioxidant effects of ascorbic acid and glutathione
Biochemical Pharmacology
Acute phase proteins in serum and cerebrospinal fluid in the course of bacterial meningitis
Clinical Biochemistry
Rapid isolation of lipoproteins and assessment of their peroxidation by high-performance liquid chromatography postcolumn chemoluminescence
Methods in Enzymology
C-reactive protein – a clinical marker in community-acquired pneumonia
Chest
Inhibition of cell membrane lipid peroxidation by cadmium- and zinc-metallothioneins
Biochimica et Biophysica Acta
IL-6 and APPs: anti-inflammatory and immunosuppressive mediators
Immunology Today
Acute phase proteins in the monitoring of inflammatory disorders
Baillière’s Clinical Rheumatology
C-reactive protein: a critical review
Pathology
Pathophysiologic correlates of acute porcine pleuropneumonia
American Journal of Veterinary Research
Inflammatory cytokine expression in swine experimentally infected with Actinobacillus pleuropneumoniae
Infection and Immunity
C-reactive protein and the acute phase response
Advances in Internal Medicine
Der Gehalt an Ascorbinsäure in Geweben von Schweinefeten und von neugeborenen Ferkeln sowie der im Blutplasma und in Geweben von Schweinen unterschiedlichen Alters, unter Berücksichtigung des Einflusses der Beshränkung der Säugezeit
Deutsche tierärtzliche Wochenschrift
C-reactive protein – a characteristic feature of health control in swine
Journal of Veterinary Medicine A
Cited by (63)
Utilization of olive mill waste waters to produce bioactive animal feed
2022, Membrane Engineering in the Circular Economy: Renewable Sources Valorization in Energy and Downstream Processing in Agro-food IndustryA multi-herd study shows that saliva is more than a reflection of serum biomarkers in pigs
2021, AnimalCitation Excerpt :This increase was not observed in saliva samples in which a decreasing tendency in Cu levels was observed, in agreement with previous studies performed in porcine saliva of diseased pigs in field conditions (Sánchez et al., 2020). Likewise, a decrease in Zn concentrations in serum samples of diseased pigs was observed in our study, which agrees with the decrease observed during bacterial infection (Baarsch et al., 2000) and endotoxemia in pigs (Lauritzen et al., 2003). Moreover, after 48 h after endotoxemia treatment, the decrease in Zn levels reverted to more than 50% of the initial levels.
Feed supplemented with polyphenolic byproduct from olive mill wastewater processing improves the redox status in blood and tissues of piglets
2015, Food and Chemical ToxicologyCitation Excerpt :For example, exposure of piglets to high levels of O2 and NO● increased inflammation and decreased surfactant function in lungs (Robbins et al., 1995). Moreover, in an experimental model of Actinobacillus pleuropneumoniae-induced pneumonia in pigs, the blood levels of the antioxidant ascorbate has been shown to decline in parallel with the progression of the disease, while its levels were normalized after antiobiotic treatment (Lauritzen et al., 2005, 2003a, 2003b). In addition, in a piglet model of deoxycholate-induced gut injury, the concentrations of nitrite, the end product of NO●, were increased in parallel with inflammation biomarkers (Miller et al., 1993).
Multiplex analysis of pro-inflammatory cytokines in serum of Actinobacillus pleuropneumoniae-infected pigs
2015, Research in Veterinary ScienceEffect of tocopherol and acetylsalicylic acid on the biochemical indices of blood in dioxin-exposed rats
2015, Environmental Toxicology and PharmacologyCitation Excerpt :The beneficial effect of tocopherol, protecting organs against the consequences of oxidative stress resulting from dioxin poisoning, is also related to its antagonistic action on the AhR receptor, leading to a blockage of CYP1A1 (Kloser et al., 2011). Another basis for the effect is replenishing the tocopherol depleted during the inflammatory response (Lauritzen et al., 2003). Studies by other authors also showed that, in a similar model involving dioxin-exposed animals, tocopherol significantly lowered the concentration of TNF (Całkosiński, 2005, 2008; Tsukamoto et al., 1995) – a cytokine responsible for reactions occurring during inflammation, including apathy and somnolence – which confirms the results obtained.
Infection dynamics and acute phase response of an Actinobacillus pleuropneumoniae field isolate of moderate virulence in pigs
2014, Veterinary MicrobiologyCitation Excerpt :Accordingly, no specific antibodies against A. pleuropneumoniae were detected throughout our study in inoculated animals which were euthanised at early time-periods (no longer than 72 hpi). In this sense, different biomarkers, such as acute phase reactants or proinflammatory cytokines, are being analyzed to determine their suitability in detection and monitoring of different diseases, such as PCP (Hultén et al., 2003; Lauritzen et al., 2003; Benga et al., 2009; Heegaard et al., 2011). In our study a significant sustained enhancement in all three acute phase proteins was observed from 24 hpi onwards.