Dairy Ingredients for Food Processing

Table 3.1. Pathogenic microorganisms associated with milk and dairy products.

Microorganism Disease condition Comments

Bacteria

Aeromonas hydrophila Can cause wound infections Opportunistic pathogen, psychrotrophic

Bacillus cereus Gastroenteritis Aerobic sporeformer, some strains psychrotrophic, can

produce an emetic toxin but such strains are rare in

milk

Brucella abortis, Br. melitensis Fever, chills, sweating, malaise Sometimes produces intermittent waves of elevated

temperature, hence called “ undulant fever ”

Campylobacter jejuni Gastroenteritis Usually self - limiting but severe complications can

arise rarely (e.g., Guillian - Barr é syndrome and

reactive arthritis)

Chronobacter (formerly

Enterobacter ) sakazakii

Meningitis, necrotizing enterocolitis Usually associated with infant formula, Not heat

resistant but grows rapidly in rehydrated feeds

Clostridium perfringens Gastroenteritis Anaerobic sporeformer, condition is usually mild

because unbound bacteria and enterotoxins are

fl ushed from the intestine, owing to profuse diarrhea

Coxiella burnetii Fever and severe headache Disease termed Q - fever, one of the organisms used to

defi ne lethality of pasteurization

Escherichia coli Gastroenteritis, some serotypes

(e.g., 0157 : H7) can produce

severe renal failure

Not all strains pathogenic, genetically promiscuous

and potentially can harbor a range of virulence

factors

Hafnia alvei Mild gastroenteritis Can be present in raw milk and is known to grow on

the surface of Camembert cheese

Klebsiella pneumoniae Gastroenteritis and pneumonia Contamination is mainly from bedding and water

Leptospira interrogens Disease varies from infl uenza type to

severe icteric form

Contamination is likely via urine of infected animals

Listeria monocytogenes Meningitis/septicemia Psychrotroph, among susceptible individuals (e.g.,

neonates, pregnant women) mortality rate is high

Mycobacterium avium subsp.

paratuberculosis

Implicated in Crohn ’ s disease Very slow growing in vitro. may survive pasteurization

Mycobacterium bovis Tuberculosis Broad host range, lethality of pasteurization partly

based on this organism

Mycobacterium tuberculosis Tuberculosis Species adapted as a human rather than animal

pathogen, usually spread via aerosols

Pseudomonas aeruginosa Gastroenteritis In addition, causal agent of cystic fi brosis

Salmonella spp. Gastroenteritis, which can be severe Disease requires ingestion of viable organism and not

via a preformed toxin

Staphylococcus aureus Gastroenteritis Symptoms produced by heat - stable toxin that can be

pre - formed in the milk, poor competitor and growth

favored by low a w

Streptococcus pyogenes Fever Disease called scarlet fever

Yersinia enterocolitica Gastroenteritis Psychrotroph

Streptococcus zooepidermicus Septicemia Condition may be complicated by glomerulonephritis

Molds

Aspergillus spp., Penicillium

spp., and Fusarium spp.

Cancer Symptoms arise from consumption/exposure to

mycotoxins which are secondary metabolites;

animals may consume moldy grain/silage and

excrete toxins in their milk

Viruses

Rotaviruses Gastroenteritis Detection in milk prevented by intrinsic antiviral

antibodies which are destroyed by acid in human

stomach

Hepatitis A Fever and nausea Virus eventually affects the liver

Polio virus Fever and nausea May cause paralysis

Protozoa

Cyyptosporidium parvum and

minis

Diarrhea Infection is by ingestion of oocysts

Entamoeba histolytica Intermittent diarrhea and constipation Infection is by ingestion of cysts

Giardia intestinalis Gastroenteritis Infection is by ingestion of cysts

Toxoplasma gondii Spontaneous abortion or congenital

defects

Mostly causes asymptomatic infection

Algae

Prototheca spp. Wound infection Especially affects immunocompromised individuals

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