Milk….One of Mother Nature’s Most Perfect Foods

MilkMilk…….One of Mother Nature.One of Mother Nature’’s s Most Perfect FoodsMost Perfect Foods

Why Bacteria in Milk Matters

SP OliverDept. Animal Science

The University of Tennesseehttp://www.tqml.utk.edu

soliver@utk.edu

Why Bacteria in Milk Matters

SP OliverSP OliverDept. Animal ScienceDept. Animal Science

The University of TennesseeThe University of Tennesseehttp://www.tqml.utk.edu

soliver@utk.edusoliver@utk.edu

got milk?got milk?got milk? Milk QualityMilk QualityMilk QualityTopic of continued debate in dairy industryIssues….

public health (residues, pathogens, toxins)processors & consumers demanding high quality

Several groups support enhancing milk quality (lower SCC & bacteria counts) via regulatory intervention….

Milk buyers/processors may only purchase high quality milk even though milk meets minimum regulatory standards

Topic of continued debate in dairy industryTopic of continued debate in dairy industry

IssuesIssues……..public health (residues, pathogens, toxins)public health (residues, pathogens, toxins)processorsprocessors & & consumers demanding high qualityconsumers demanding high quality

Several groups support enhancing milk Several groups support enhancing milk quality (lower SCC & bacteria counts) via quality (lower SCC & bacteria counts) via regulatory interventionregulatory intervention……..

Milk buyers/processors may only purchase Milk buyers/processors may only purchase high quality milk even though milk meets high quality milk even though milk meets minimum regulatory standardsminimum regulatory standards

Quality MilkQuality MilkQuality MilkLow SCC

Low bacterial count Free of human pathogens

Free of antibiotic residues

Low SCCLow SCC

Low bacterial count Low bacterial count Free of human pathogens Free of human pathogens

Free of antibiotic residuesFree of antibiotic residues

Bacteria in MilkBacteria in MilkRegulatory limit defined….

< 50,000/ml in Ontario….100,000/ml in US….

Safety concerns….Some pathogens in milk can cause disease in humans

Quality concerns….Impacts taste, ↓ shelf-life, alter milk composition,↓ yieldHigh milk bacteria count associated with mastitis-causing bacteria, poor hygiene & sanitation, improper milk cooling, environmental contamination….

Regulatory limit definedRegulatory limit defined……. . < 50,000/ml in Ontario< 50,000/ml in Ontario……..100,000/ml in US100,000/ml in US……..

Safety concernsSafety concerns……..Some pathogens in milk can cause disease in Some pathogens in milk can cause disease in humanshumans

Quality concernsQuality concerns……..Impacts tasteImpacts taste, , ↓↓ shelfshelf--life, life, alter milk composition,alter milk composition,↓↓ yieldyieldHigh milk bacteria count associated with mastitisHigh milk bacteria count associated with mastitis--causing bacteria, poor hygiene & sanitation, improper causing bacteria, poor hygiene & sanitation, improper milk cooling, environmental contaminationmilk cooling, environmental contamination……..

Bacteria Found in MilkBacteria Found in Milk

Mastitis pathogens

Psychrotrophic “cold tolerant”bacteria

Thermoduric spoilage bacteria

Foodborne pathogens

Mastitis pathogens

Psychrotrophic “cold tolerant”bacteria

Thermoduric spoilage bacteria

Foodborne pathogens

Bacteria & Milk QualityMilk Is Pasteurized….

So What’s the Concern?

Bacteria & Milk QualityMilk Is PasteurizedMilk Is Pasteurized……. .

So WhatSo What’’s the Concern?s the Concern?

Reduced quality of raw & processed milk & milk products associated with psychrotrophic bacteria & thermoduric spoilage bacteriaMost destroyed by pasteurization….some produce proteolytic & lipolytic enzymes that survive pasteurization

These enzymes degrade protein & fat in raw & processed products….reduce shelf-life & alter taste

Reduced quality of raw & processed milk Reduced quality of raw & processed milk & & milk products associated with psychrotrophic milk products associated with psychrotrophic bacteria & thermoduric spoilage bacteriabacteria & thermoduric spoilage bacteriaMost Most destroyed by pasteurizationdestroyed by pasteurization…….some .some produce proteolytic & lipolytic enzymes that produce proteolytic & lipolytic enzymes that survive pasteurizationsurvive pasteurization

These enzymes degrade protein & fat in raw & These enzymes degrade protein & fat in raw & processed productsprocessed products…….reduce shelf.reduce shelf--life & alter life & alter tastetaste

Most significant cause ↓ milk shelf-life…. Gram-neg psychrotrophic bacteria ….these bacteriagenerally do not survive pasteurization

Post-pasteurization contamination with Gram-neg psychrotrophic bacteria which can grow at refrigeration temperatures significant cause of ↓milk shelf-life

Certain bacteria (spore-forming strains of Bacillus & Paenibacillus) that survive pasteurization can grow at refrigeration temperatures & cause spoilage of milk beyond 14 days post-processing

Most significant Most significant cause cause ↓↓ milk shelfmilk shelf--lifelife…….. GramGram--neg psychrotrophic bacterianeg psychrotrophic bacteria …….these.these bacteriabacteriagenerally do not survive pasteurizationgenerally do not survive pasteurization

PostPost--pasteurization contaminationpasteurization contamination with Gramwith Gram--neg neg psychrotrophic bacteria which can grow at psychrotrophic bacteria which can grow at refrigeration temperatures significant cause of refrigeration temperatures significant cause of ↓↓milk shelfmilk shelf--lifelife

Certain bacteria (sporeCertain bacteria (spore--forming strains of Bacillus forming strains of Bacillus & Paenibacillus) that survive pasteurization can & Paenibacillus) that survive pasteurization can grow at refrigeration temperatures & cause grow at refrigeration temperatures & cause spoilage of milk beyond 14 days postspoilage of milk beyond 14 days post--processingprocessing

Quality & Shelf Life of Pasteurized Fluid Milk

Quality & Shelf LifeQuality & Shelf Life of of Pasteurized Fluid Milk Pasteurized Fluid Milk

How Do Bacteria Get Into BTM ?

How Do Bacteria Get Into BTM ?

BeddingBeddingBedding

Infected udderInfected udderInfected udder

Udder, teat & teat endUdder, teat & teat endUdder, teat & teat end

Manure Manure Manure

SoilSoilSoil

Milking equipment, water, cleaning

Milking equipment, water, Milking equipment, water, cleaningcleaning

Bulk tank Bulk tank

ColiformsNon coliformsStreptococciEnterococci

ColiformsColiformsNon coliformsNon coliformsStreptococciStreptococciEnterococciEnterococci

Escherichia coli, Citrobacter Escherichia coli, Citrobacter fruendii, Klebsiellafruendii, Klebsiella sppspp, , EnterobacterEnterobacter spp. spp. AcinetobacterAcinetobacter, , Hafnia alveiHafnia alvei, , MoraxellaMoraxella, , P. aeruginosaP. aeruginosa, , P. P. fluorescensfluorescens, , PseudomonasPseudomonasspp., spp., BacillusBacillus spp., spp., SerratiaSerratia spp.spp.S. salivarius, S. bovis, S. S. salivarius, S. bovis, S. equinus, S. uberis, E. faecalis, equinus, S. uberis, E. faecalis, E. faecium. E. avium, E. durans, E. faecium. E. avium, E. durans, E. malodoratus, S. thermophilusE. malodoratus, S. thermophilus

ColiformsPseudomonasStreptococciEnterococci

Bacillus

ColiformsColiformsPseudomonasPseudomonasStreptococciStreptococciEnterococciEnterococci

BacillusBacillus

Escherichia coli, Citrobacter Escherichia coli, Citrobacter fruendii, Klebsiellafruendii, Klebsiella sppspp, , EnterobacterEnterobacter spp. spp. AcinetobacterAcinetobacter, , Hafnia alveiHafnia alvei, , MoraxellaMoraxella, , P. P. aeruginosaaeruginosa, , P. fluorescensP. fluorescens, , PseudomonasPseudomonas spp., spp., BacillusBacillusspp., spp., SerratiaSerratia spp.spp., S. bovis, S. , S. bovis, S. uberis, E. faecalis, E. faecium. E. uberis, E. faecalis, E. faecium. E. aviumavium

ColiformsNon coliformsStreptococciEnterococci

CNS

ColiformsColiformsNon coliformsNon coliformsStreptococciStreptococciEnterococciEnterococci

CNSCNS

Coagulase neg. Staphylococci, Coagulase neg. Staphylococci, S. bovis, S. uberis, E. faecalis, E. S. bovis, S. uberis, E. faecalis, E. faecium, E. avium, Escherichia faecium, E. avium, Escherichia coli, Citrobacter fruendii, coli, Citrobacter fruendii, Klebsiella spp, Enterobacter Klebsiella spp, Enterobacter spp. Pseudomonas spp. Bacillus spp. Pseudomonas spp. Bacillus spp. spp.

S. aureusS. uberis

S. agalactiaeMycoplasma

S. dysgalactiaeMany others

S. aureusS. aureusS. uberisS. uberis

S. agalactiaeS. agalactiaeMycoplasmaMycoplasma

S. dysgalactiaeS. dysgalactiaeMany othersMany others

Pseudomonas, Enterococci, Lactococci, Bacillus, Coliforms

Pseudomonas, Enterococci, Pseudomonas, Enterococci, Lactococci, Bacillus, Lactococci, Bacillus, ColiformsColiforms

Assessing Milk Quality

Standard Plate Count (SPC)

Laboratory Pasteurization Count (LPC)

Coliform Count (CC)

Preliminary Incubation Count (PI)

Assessing Milk QualityAssessing Milk Quality

Standard Plate Count (SPC)Standard Plate Count (SPC)

Laboratory Pasteurization Count (LPC)Laboratory Pasteurization Count (LPC)

Coliform Count (CC)Coliform Count (CC)

Preliminary Incubation Count (PI)Preliminary Incubation Count (PI)

Most commonly used throughout industry….

Indication of total aerobic bacteria present in milk

Milk samples plated & incubated 48 hr at 32oC (90oF)….bacterial colonies counted

Most commonly used throughout Most commonly used throughout industryindustry……..

Indication of total aerobic bacteria Indication of total aerobic bacteria present in milk present in milk

Milk samples plated & incubated 48 hr at Milk samples plated & incubated 48 hr at 3232ooC (90C (90ooF)F)…….bacterial colonies counted.bacterial colonies counted

Standard Plate Count (SPC) Standard Plate Count (SPC) Standard Plate Count (SPC)

Good Acceptable Concern (low) (medium) (high)

< 10,000 < 20,000 > 20,000

Good Good AcceptableAcceptable Concern Concern (low)(low) (medium)(medium) (high)(high)

< 10,000< 10,000 < 20,000< 20,000 > 20,000> 20,000

Standard Plate CountStandard Plate Count

05000

1000015000200002500030000350004000045000

< 10,000 < 20,000 > 20,000

Improper cleaning of milking systemStrep agalactiae mastitisDirty udders & teats, dirty equipment Inability to cool milk rapidly to 40°FFailure of water heater Failure in sanitationResidual water in linesWet & humid weather

Wet milking conditions

Improper cleaning of milking systemImproper cleaning of milking systemStrep agalactiae mastitisStrep agalactiae mastitisDirty udders & teats, dirty equipment Dirty udders & teats, dirty equipment

Inability to cool milk rapidly to 40Inability to cool milk rapidly to 40°°FFFailure of water heater Failure of water heater

Failure in sanitationFailure in sanitation

Residual water in linesResidual water in lines

Wet & humid weather Wet & humid weather

Wet milking conditionsWet milking conditions

Reasons for high SPCReasons for high SPCReasons for high SPCPerformed by holding milk at 12.8°C (55°F) for 18 hr…. bacteria enumerated using SPC

Theory….normal microbial flora of cow (skin & teat bacteria) will NOT grow substantially during incubation at 55°F….however, bacteria associated with inadequate hygiene practices will be able to grow….PI counts should ALWAYS be compared to fresh SPC

Goal….detect farm hygiene inadequacies that may not be apparent with SPC alone

Factors influencing PI counts….Precision of incubation/tempAge & storage of milk sampleTypes, number, stage of growth & growth temp of bacteria in sample

Performed by holding milk at 12.8Performed by holding milk at 12.8°°C (55C (55°°F) for 18 hrF) for 18 hr……. . bacteria enumerated using SPC bacteria enumerated using SPC

TheoryTheory…….normal microbial flora of cow (skin & teat .normal microbial flora of cow (skin & teat bacteria) will NOT grow substantially during incubation at bacteria) will NOT grow substantially during incubation at 5555°°FF…….however, bacteria associated with inadequate .however, bacteria associated with inadequate hygiene practices will be able to growhygiene practices will be able to grow……..PI counts should PI counts should ALWAYSALWAYS be compared to fresh SPCbe compared to fresh SPC

GoalGoal…….detect farm hygiene inadequacies that may not be .detect farm hygiene inadequacies that may not be apparent with SPC aloneapparent with SPC alone

Factors influencing PI countsFactors influencing PI counts……..Precision of incubation/tempPrecision of incubation/tempAge & storage of milk sampleAge & storage of milk sampleTypes, number, stage of growth & growth temp of Types, number, stage of growth & growth temp of bacteria in samplebacteria in sample

PI CountsPI CountsPI Counts

Murphy, 2007

010,00020,00030,00040,00050,00060,00070,00080,00090,000

< 10,000 < 50,000 > 50,000

Generally > SPC....a 3-4 fold higher PI count than SPC suggests….

1. Cleaning & sanitation of the milking system

2. Poor udder preparation before milking

3. Failure to cool milk rapidly 4. Prolonged storage times5. Milking cows with wet teats

6. Extremely wet & humid conditions….PI counts & SPC spike day after rain when cows milked that are wet & dirtier

Generally > SPC....a 3-4 fold higher PI count than SPC suggests….

1. Cleaning & sanitation of the milking system

2. Poor udder preparation before milking

3. Failure to cool milk rapidly 4. Prolonged storage times5. Milking cows with wet teats 5. Milking cows with wet teats

6. Extremely wet & humid 6. Extremely wet & humid conditionsconditions……..PI counts & SPC PI counts & SPC spike day after rain when cows spike day after rain when cows milked that are wet & dirtiermilked that are wet & dirtier

PI Counts PI Counts PI Counts Good Acceptable Concern (low) (medium) (high)

<10,000 <50,000 >50,000<3-4X SPC >3-4X SPC

GoodGood AcceptableAcceptable Concern Concern (low)(low) (medium)(medium) (high)(high)

<10,000<10,000 <50,000<50,000 >50,000>50,000<3<3--4X SPC4X SPC >3>3--4X SPC4X SPC

Measures ‘heat-loving’ (thermoduric) bacteriaResistant environmental bacteriaSurvive pasteurization

Sample heated to 62.8°C (143°F) & held for 30 min, then bacterial colonies counted

Destroys most mastitis pathogens….selects for those bacteria that can survive pasteurization temperatures Not a regulatory test….some milk plants perform this test to ensure quality of final product

Measures Measures ‘‘heatheat--lovingloving’’ (thermoduric) bacteria(thermoduric) bacteriaResistant environmental bacteriaResistant environmental bacteriaSurvive pasteurizationSurvive pasteurization

Sample heated to 62.8Sample heated to 62.8°°C (143C (143°°F) & held for 30 F) & held for 30 min, then bacterial colonies countedmin, then bacterial colonies counted

Destroys most mastitis pathogensDestroys most mastitis pathogens…….selects .selects for those bacteria that can survive for those bacteria that can survive pasteurization temperatures pasteurization temperatures Not a regulatory testNot a regulatory test…….some milk plants .some milk plants perform this test to ensure quality of final perform this test to ensure quality of final productproduct

Lab Pasteurization Count (LPC) Lab Pasteurization Count (LPC) Lab Pasteurization Count (LPC)

Good Acceptable Concern(low) (medium) (high) <100 <100 - 200 >200

Good Acceptable Concern(low) (medium) (high) <100 <100 - 200 >200

050

100150200250300350400450

< 100 < 100-200 > 200

Unclean milking equipment ?Most often seen with persistent cleaning problems

Faulty milking machine or worn out parts ?Leaky pumps, deteriorated pipe line gaskets, inflations and other rubber parts, and milkstone deposits

Extremely dirty cows ?Significant levels of contamination from soiled cows can also contribute to high LPC

Unclean milking equipment ?Most often seen with persistent cleaning problems

Faulty milking machine or worn out parts ?Leaky pumps, deteriorated pipe line gaskets, inflations and other rubber parts, and milkstone deposits

Extremely dirty cows ?Significant levels of contamination from soiled cows can also contribute to high LPC

Why Are LPCWhy Are LPC’’s High?s High?LPC ClassificationsLPC ClassificationsLPC Classifications Coliform Count Coliform Count Coliform Count Not a regulatory test

Measures coliform bacteria

Associated with fecal & environmental contamination

No legal limits for raw milk unless coliforms cause SPC to exceed 100,000/ml

Achievable goal: < 50 cfu/ml

Not a regulatory testNot a regulatory test

Measures coliform bacteriaMeasures coliform bacteria

Associated with fecal & Associated with fecal & environmental contaminationenvironmental contamination

No legal limits for raw milk No legal limits for raw milk unless coliforms cause SPC to unless coliforms cause SPC to exceed 100,000/mlexceed 100,000/ml

Achievable goal: < 50 cfu/mlAchievable goal: < 50 cfu/ml

Good Acceptable Concern (low) (medium) (high)<50 <50-100 >100

GoodGood AcceptableAcceptable Concern Concern (low)(low) (medium) (medium) (high)(high)<50<50 <50<50--100 100 >100>100

050

100150200250300350400

< 50 < 100 > 100

High counts suggest:

1. Poor milking practices

2. Dirty equipment

3. Contaminated water

4. Dirty milking facilities

5. Cows with mastitis

High counts High counts suggest:suggest:

1. Poor milking practices

2. Dirty equipment

3. Contaminated water

4. Dirty milking facilities

5. Cows with mastitis

Coliform CountColiform Count Quality MilkQuality MilkQuality MilkLow SCC

Low bacterial count Free of human pathogens

Free of antibiotic residues

Low SCCLow SCC

Low bacterial count Low bacterial count Free of human pathogensFree of human pathogens

Free of antibiotic residuesFree of antibiotic residues

Should Dairy Industry Be Concerned About Food Safety?

Should Dairy Industry Be Should Dairy Industry Be Concerned About Food Safety?Concerned About Food Safety?

Raw milk contains foodborne pathogens & toxins that can cause human disease & illness

Human disease outbreaks associated with consumption of unpasteurized milk

Raw milk consumed by dairy producers & their families, farm employees, neighbors, raw milk advocatesContaminated raw milk could contaminate processing & slaughter facilities

Raw milk contains foodborne pathogens & toxins Raw milk contains foodborne pathogens & toxins that can cause human disease & illnessthat can cause human disease & illness

Human disease outbreaks associated with Human disease outbreaks associated with consumption of unpasteurized milkconsumption of unpasteurized milk

Raw milk consumed by dairy producers & their Raw milk consumed by dairy producers & their families, farm employees, neighbors, raw milk families, farm employees, neighbors, raw milk advocatesadvocates

Contaminated raw milk could contaminate Contaminated raw milk could contaminate processing & slaughter facilities processing & slaughter facilities

You Bet & Here’s Why!!!!You Bet & HereYou Bet & Here’’s Why!!!!s Why!!!!

Raw Milk ConsumptionRaw Milk ConsumptionEstimates difficult to find….assumed that < 1% of US population consume raw unpasteurized milk & products made from raw milk….(Yilmaz et al., 2009)

Many dairy farm families, farm employees & neighbors drink raw milk from bulk tank

Consumption increasing…. 3.2% of those surveyed in CA had consumed raw milk (Headrick et al., 1997)3.5% who participated in a 2002 survey consumed unpasteurized milk within a 7 day period before survey was taken (CDC, 2004)Promoted by raw milk advocates Demand for natural, unprocessed foodsConsumers who support “produce, sell & buy local”

Estimates difficult to findEstimates difficult to find…….assumed that .assumed that < 1% < 1% of of US population consume raw unpasteurized milk & US population consume raw unpasteurized milk & products made from raw milkproducts made from raw milk…….(Yilmaz et al., 2009).(Yilmaz et al., 2009)

Many dairy farm families, farm employees & neighbors drink raw Many dairy farm families, farm employees & neighbors drink raw milk from bulk tankmilk from bulk tank

Consumption increasingConsumption increasing……. . 3.2% of those surveyed in CA had consumed raw milk (Headrick 3.2% of those surveyed in CA had consumed raw milk (Headrick et al., 1997)et al., 1997)3.5% who participated in a 2002 survey consumed unpasteurized 3.5% who participated in a 2002 survey consumed unpasteurized milk within a 7 day period before survey was taken (CDC, 2004)milk within a 7 day period before survey was taken (CDC, 2004)Promoted by raw milk advocates Promoted by raw milk advocates Demand for natural, unprocessed foodsDemand for natural, unprocessed foodsConsumers who support Consumers who support ““produce, sell & buy localproduce, sell & buy local””

Raw Milk ConsumptionRaw Milk ConsumptionReasons for consuming raw milk….

Health benefits….Enhanced nutritional qualities….Better taste….“Green” movement….Freedom of choice….

Science-based data to substantiate these claims limited & in most cases lacking

Reasons for consuming raw milkReasons for consuming raw milk……..Health benefitsHealth benefits……..Enhanced nutritional qualitiesEnhanced nutritional qualities……..Better tasteBetter taste……..““GreenGreen”” movementmovement……..Freedom of choiceFreedom of choice……..

ScienceScience--based data to substantiate these based data to substantiate these claims limited & in most cases lackingclaims limited & in most cases lacking

Raw Milk ConsumptionRaw Milk ConsumptionReasons NOT to consume raw milk….FOOD SAFETY….FOOD SAFETY….FOOD SAFETY

much science-based data to substantiate food safety hazards of consuming raw milk

Cost….commercial raw milk demands a premium price….even more than organic milk

Costs associated with disease outbreaks, illness & product recalls

Reasons Reasons NOTNOT to consume raw milkto consume raw milk……..FOOD SAFETYFOOD SAFETY…….FOOD SAFETY.FOOD SAFETY…….FOOD SAFETY.FOOD SAFETY

much sciencemuch science--based data to substantiate food safety based data to substantiate food safety hazards of consuming raw milkhazards of consuming raw milk

CostCost…….commercial raw milk demands a premium .commercial raw milk demands a premium priceprice…….even more than organic milk.even more than organic milk

Costs associated with disease outbreaks, illness Costs associated with disease outbreaks, illness & product recalls& product recalls

Is Raw Milk Safe ?Is Raw Milk Safe ?May contain several pathogens:

Enterotoxigenic Staph. aureusCampylobacter jejuniSalmonella speciesE. coli (EHEC & ETEC)Listeria monocytogenesMycobacterium tuberculosisMycobacterium paratuberculosis Brucella spp (abortus –cattle) (melitensis- goats)Coxiella burnetiiYersinia enterocolitica…..many more

May contain several pathogens:May contain several pathogens:Enterotoxigenic Staph. aureusEnterotoxigenic Staph. aureusCampylobacter jejuniCampylobacter jejuniSalmonella speciesSalmonella speciesE. coli (EHEC & ETEC)E. coli (EHEC & ETEC)Listeria monocytogenesListeria monocytogenesMycobacterium tuberculosisMycobacterium tuberculosisMycobacterium paratuberculosis Mycobacterium paratuberculosis Brucella spp (abortus Brucella spp (abortus ––cattle) cattle) (melitensis(melitensis-- goats)goats)Coxiella burnetiiCoxiella burnetiiYersinia enterocoliticaYersinia enterocolitica……..many more..many more

Bulk tank milk plated on blood agar

Bulk tank milk plated Bulk tank milk plated on blood agaron blood agar

ABSOLUTELY NOT!!!!ABSOLUTELYABSOLUTELY NOT!!!!NOT!!!! Staphylococcus aureusStaphylococcus aureusFound frequently in BTM….significant cause of mastitis throughout worldProduce enterotoxins (A-H) & toxic shock syndrome toxin (TSST-1)….enterotoxigenic Staph aureus can cause disease & food poisoning73 of 78 (93.6%) Staph. aureus isolated from milk of cows with mastitis positive for one or more enterotoxin genes; 69 of 73 (88.5%) harbored > 1 enterotoxin gene (Srinivasan & Oliver, 2006)

Large outbreak in Japan caused by consumption of low-fat milk produced from skim milk powder contaminated with Staph aureus enterotoxin A

Found frequently in BTMFound frequently in BTM…….significant cause of .significant cause of mastitis throughout worldmastitis throughout worldProduce enterotoxins (AProduce enterotoxins (A--H) & toxic shock H) & toxic shock syndrome toxin (TSSTsyndrome toxin (TSST--1)1)…….enterotoxigenic Staph .enterotoxigenic Staph aureus can cause disease & food poisoningaureus can cause disease & food poisoning

73 of 78 (93.6%) Staph. aureus isolated from milk 73 of 78 (93.6%) Staph. aureus isolated from milk of cows with mastitis positive for one or more of cows with mastitis positive for one or more enterotoxin genes; 69 of 73 (88.5%) harbored > 1 enterotoxin genes; 69 of 73 (88.5%) harbored > 1 enterotoxin gene enterotoxin gene (Srinivasan & Oliver, 2006)(Srinivasan & Oliver, 2006)

Large outbreak in Japan caused by consumption Large outbreak in Japan caused by consumption of lowof low--fat milk produced from skim milk powder fat milk produced from skim milk powder contaminated with Staph aureus enterotoxin Acontaminated with Staph aureus enterotoxin A

Raw milk long been recognized in transmission of a variety of microbial pathogens

29 outbreaks/yr in US from 1880 & 1907 (Chin, 1982)

Caused ~ 25% of all reported disease outbreaks from contaminated food & water in 1938; since then milkborne disease outbreaks decreased significantly(Grade A PMO, 2007)

From 1973-1992, 46 outbreaks (~2.4/yr) reported(Headrick et al., 1998)

From 1993-2006, 68 outbreaks (~5.2/yr) associated with unpasteurized milk or milk products made from unpasteurized milk reported (CDC, 2008)

Raw milk long been recognized in transmission of a Raw milk long been recognized in transmission of a variety of microbial pathogens variety of microbial pathogens

29 outbreaks/yr in US from 1880 & 190729 outbreaks/yr in US from 1880 & 1907 (Chin, 1982)(Chin, 1982)

Caused ~ 25% of all reported disease outbreaks from Caused ~ 25% of all reported disease outbreaks from contaminated food & water in 1938; since then contaminated food & water in 1938; since then milkborne disease outbreaks decreased significantlymilkborne disease outbreaks decreased significantly(Grade A PMO, 2007)(Grade A PMO, 2007)

From 1973From 1973--1992, 46 outbreaks (~2.4/yr1992, 46 outbreaks (~2.4/yr) ) reportedreported(Headrick et al., 1998) (Headrick et al., 1998)

From 1993From 1993--2006, 68 outbreaks (~5.2/yr) associated 2006, 68 outbreaks (~5.2/yr) associated with unpasteurized milk or milk products made from with unpasteurized milk or milk products made from unpasteurized milk reportedunpasteurized milk reported (CDC, 2008)(CDC, 2008)

Milkborne Disease Outbreaks

Milkborne Disease Milkborne Disease OutbreaksOutbreaks

PrevalencePrevalenceMean (range)Mean (range)

PathogenPathogen

3.6 (0.2 3.6 (0.2 –– 8.9)8.9)Salmonella spp.Salmonella spp.

4.4 (1.0 4.4 (1.0 –– 12.6)12.6)L monocytogenesL monocytogenes1.8 (0.8 1.8 (0.8 –– 3.8)3.8)STEC E. coliSTEC E. coli3.7 (0.4 3.7 (0.4 –– 12.3)12.3)C jejuniC jejuni

Foodborne Pathogens in Bulk Tank Milk

Foodborne Pathogens Foodborne Pathogens in Bulk Tank Milkin Bulk Tank Milk

Summary of 20 studies conducted between 1982 and 2004Summary of 20 studies conducted between 1982 and 2004

Detection of Foodborne Pathogens In the Dairy Farm Environment

Detection of Foodborne Pathogens Detection of Foodborne Pathogens In the Dairy Farm EnvironmentIn the Dairy Farm Environment

TN RiverTN River

UT Dairy Study SummaryUT Dairy Study Summary

Most (44%) foodborne pathogens were isolated from fecal samples

Bovine feces, lagoon water, bedding, bird droppings, & rats were areas of concern on dairies studiesGood manure management is important for dairy farm hygiene

Most (44%) foodborne pathogens Most (44%) foodborne pathogens were isolated from fecal sampleswere isolated from fecal samples

Bovine feces, lagoon water, Bovine feces, lagoon water, bedding, bird droppings, & rats bedding, bird droppings, & rats were areas of concern on dairies were areas of concern on dairies studiesstudies

Good manure management is Good manure management is important for dairy farm hygieneimportant for dairy farm hygiene

Recycling of Foodborne Pathogens on the FarmRecycling of Foodborne Recycling of Foodborne Pathogens on the FarmPathogens on the Farm

RAW MILK

GOT Milk ?GOT Milk ?Make Sure It’s Pasteurized

Make Sure ItMake Sure It’’s s PasteurizedPasteurized

Quality MilkQuality MilkSafety & quality of dairy products start at the farm level & continues throughout processing

cannot transform a low(er) quality raw product into a high quality finished product

Consumers/processors demanding a higher quality raw product…low SCC & bacteria counts

Many tests used to determine qualityregulatory….SCC & bacteria countsnon-regulatory but used by industry….PIC, LPC, CC

To meet ↑ quality standards, producers mustadopt production practices that reduce mastitis & bacterial contamination of BTM

Safety & quality of dairy products start at the Safety & quality of dairy products start at the farm level & continues throughout processingfarm level & continues throughout processing

cannot transform a low(er) quality raw product into a cannot transform a low(er) quality raw product into a high quality finished producthigh quality finished product

Consumers/processors demanding a higher Consumers/processors demanding a higher quality raw productquality raw product……low SCC & bacteria countslow SCC & bacteria counts

Many tests used to determine qualityMany tests used to determine qualityregulatoryregulatory…….SCC & bacteria counts.SCC & bacteria countsnonnon--regulatory but used by industryregulatory but used by industry…….PIC, LPC, CC.PIC, LPC, CC

To meet To meet ↑↑ quality standards, pquality standards, producers roducers mustmustadopt production practices that reduce mastitis adopt production practices that reduce mastitis & bacterial contamination of BTM& bacterial contamination of BTM

McCord Hall Fire Dec. 2009A few pictures of

Lab 56Lab 57

Taken the day after the fire, before any cleanup had started

McCord Hall Fire Dec. 2009A few pictures of

Lab 56Lab 57

Taken the day after the fire, before any cleanup had started

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