Measurement of Intervention Measurement of Intervention Strategies for the Treatment and Strategies for the Treatment and

(Prevention?) of Mycoplasmal (Prevention?) of Mycoplasmal Pneumonia using a Model Pneumonia using a Model

SystemSystem

Eileen L. Thacker, DVM, PhD, Eileen L. Thacker, DVM, PhD, DACVMDACVM

Iowa State UniversityIowa State University

Measurement of Intervention Measurement of Intervention StrategiesStrategies

• Goals and measurements:Goals and measurements:– productivityproductivity– clinical disease - coughingclinical disease - coughing– percentage of pneumonia – lung lesionspercentage of pneumonia – lung lesions

• macroscopicmacroscopic• microscopicmicroscopic

– number of organismsnumber of organisms• reductionreduction• sterilizationsterilization

This will determine what This will determine what parameters need to be measuredparameters need to be measured

What do we need to measure for What do we need to measure for antibiotics?antibiotics?

• Production Production parametersparameters

• Clinical diseaseClinical disease• Percentage of Percentage of

pneumoniapneumonia• Number of organismsNumber of organisms

a

Low Adherent High Adherent

Control

M. hyopneumoniaeM. hyopneumoniae

• Isolation of the organismIsolation of the organism– DifficultDifficult– Limited number of field isolates available – Limited number of field isolates available –

virulence?virulence?

• Growth of the organismsGrowth of the organisms

• Long term effect of culture on organismLong term effect of culture on organism

First StepFirst Step

• Determine in vitro susceptibilities and the Determine in vitro susceptibilities and the MICMIC– field isolatesfield isolates

• Culture techniquesCulture techniques

• In vitro culture techniquesIn vitro culture techniques

• Care must be taken when interpreting in Care must be taken when interpreting in relation to results in the pigrelation to results in the pig

In the Pig - AloneIn the Pig - Alone

• Pure infectionPure infection– strain 232strain 232– others???others???

• Model Model – culture vs lung homogenateculture vs lung homogenate

• Production parametersProduction parameters

• Percentage of pneumonia – consistencyPercentage of pneumonia – consistency

• Number of organisms – what assays?Number of organisms – what assays?

Field TrialsField Trials

• What mimics “the real world”What mimics “the real world”– Variation between systemsVariation between systems– What pathogensWhat pathogens– Identification of pathogensIdentification of pathogens– Role of other pathogensRole of other pathogens

• What do we measure?What do we measure?

• Antibiotic effect on secondary pathogensAntibiotic effect on secondary pathogens

Model Field TrialsModel Field Trials

• Co-infections?Co-infections?– M. hyopneumoniaeM. hyopneumoniae– P. multocidaP. multocida– APPAPP– PRRSVPRRSV– SIVSIV– CircoCirco– etc. – where do we etc. – where do we

stop?stop?

AnswersAnswers

• Difficult to determineDifficult to determine

• Best needs and interests of the industryBest needs and interests of the industry– what does what does M. hyopneumoniaeM. hyopneumoniae on the label on the label

mean?mean?

• Can be doneCan be done– CTC has been shown if administered prior to CTC has been shown if administered prior to

challenge to reduce number of organismschallenge to reduce number of organisms– unsuccessful with othersunsuccessful with others

Questions - ManyQuestions - Many