Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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Jacobs-Reitsma W (2000) Campylobacter in the food

supply. In: Nachamkin I and Blaser MJ (eds) Campylo-

bacter, 2nd edn. pp. 467–481. Washington, DC: Ameri-

can Society for Microbiology.

Nachamkin I and Skirrow MB (1998) Campylobacter,

Arcobacter, and Helicobacter. In: Collier L, Balows A

and Sussman M (eds) Topley and Wilson’s Microbiology

and Microbial Infections, 9th edn. vol. 2, pp.

1237–1256. London: Edward Arnold.

Skirrow MB (1998) Infection with Campylobacter and

Arcobacter. In: Collier L, Balows A and Sussman M

(eds) Topley and Wilson’s Microbiology and Microbial

Infections, 9th edn. vol. 3, pp. 567–580. London:

Edward Arnold.

Solomon EB and Hoover DG (1999) Campylobacter

jejuni: a bacterial paradox. Journal of Food Safety 19:

121–136.

Todd ECD (1997) Epidemiology of foodborne diseases: a

worldwide review. World Health Statistics Quarterly 50:

30–50.

Wesley IV (1996) Helicobacter and Arcobacter species:

risks for foods and beverages. Journal of Food Protec-

tion 59: 1127–1132.

Detection

M B Skirrow, Gloucestershire Royal Hospital,

Gloucester, UK

Introduction

0001 The conventional means of detecting campylobacters

is by isolation in culture. In this article their micro-

aerobic growth requirements and special needs for

isolation from foods are described, including selective

enrichment and plating on selective agar. Direct

detection of campylobacters by immunological and

DNA probe techniques are becoming more sensitive

and specific by the application of polymerase chain

reaction (PCR) methods, but they are as yet too com-

plex to be adopted routinely. Campylobacters can

be provisionally identified by phenotypic methods

in most laboratories, but definitive identification

requires molecular methods that are available only

in reference laboratories. Strain typing of campylo-

bacters (serotyping, phage typing, molecular typing)

is also best performed in reference laboratories. Ad-

vances in molecular typing in particular are paving

the way for better source tracing and understanding

of the epidemiology of campylobacter infection.

Principles of Campylobacter Cultivation

0002The failure of traditional cultural methods to provide

the conditions necessary for the growth of campylo-

bacters was the main reason why their role in human

disease remained hidden for so long. The main pecu-

liarity of campylobacters is that they are strictly

microaerophilic and require specially prepared at-

mospheres for satisfactory growth. Specific selection,

either by means of selective media or filtration, is

essential for their isolation from feces or other

specimens containing mixed organisms. Moreover,

they only grow well on supplemented media, and

Campylobacter jejuni, C. coli,andC. lari – the so-

called thermophilic group that causes campylobacter

enteritis – have an optimum growth temperature of

42–43



Oxygen Sensitivity

0003Oxygen sensitivity is the most critical factor in the

cultivation of campylobacters. Campylobacters have

a respiratory type of metabolism based on the krebs

cycle, so oxygen is necessary for growth; yet oxygen

at atmospheric pressures is toxic. This toxicity is due

to superoxides and free radicals that form in unsup-

plemented media exposed to air, particularly in the

light. Campylobacters are especially vulnerable to

these compounds despite being able to produce super-

oxide dismutase and catalase. They are most vulner-

able in the resting phase; once they have started to

grow they become more oxygen-tolerant, probably

owing to the production of nicotinamide adenine

dinucleotide (NAD) or nicotinamide adenine di-

nucleotide phosphate (NADP), which forms a

physiological barrier that protects oxygen-sensitive

enzymes. The practical points that arise from this

are twofold:

0004Heavy inocula are required to initiate growth on

unsupplemented media. Large populations usually

have a few bacteria that are able to start growing

and thereby create conditions suitable for other

cells to grow. The result of seeding campylobacters

on unsupplemented media tends to be either

confluent growth or none at all.

0005The key supplements for growing campylo-

bacters are agents that neutralize superoxides

and free radicals; any nutrient value they have

is incidental. Blood, hemin, hematin, activated

charcoal, dihydroxyphenyl, and iron compounds

are examples of such agents. A simple and

widely used supplement is the triple combination

of ferrous sulfate, sodium metabisulfite, and

sodium pyruvate, each at a final concentration of

0.025% (FBP).

786

CAMPYLOBACTER

/Detection

Detection in Food by Culture

0006 The isolation of campylobacters from food is more

difficult than from the feces of a patient with cam-

pylobacter enteritis, as there are usually far fewer

organisms present. For fecal specimens direct plate

culture is normally adequate – indeed, organisms

may be so plentiful that a presumptive diagnosis can

be made by direct microscopy – but for food, selective

enrichment cultures are essential. Possible exceptions

are raw poultry products, which may be so heavily

contaminated that enrichment is not critical; indeed,

for some chicken samples enrichment has proved to

be less sensitive than direct plating.

0007 The principle of the enrichment method is to incu-

bate the food (after stomaching or other treatment to

break it down) in a selective broth for 24 – 48 h and

then subculture on a selective agar for the isolation

and identification of individual colonies. However,

for campylobacters that have been subjected to hot

or cold stress, which causes sublethal injury, other

techniques may be necessary. As the treatment the

foods have received is not always known, there is

much to be said for including the more sensitive

techniques routinely.

0008 When properly carried out, cultural methods are

able to detect 1 campylobacter colony-forming unit

(CFU) in 2 g food that contains at least 10

1

other bacteria.

Specimen Handling and Transport

0009 The correct handling and preservation of specimens

are crucial for food specimens; incorrect handling

negates the value of sensitive isolation procedures.

The three most important factors are refrigeration

(as near to 4



C as possible), exclusion of oxygen,

and prevention of drying. Oxygen may be excluded

by gassing with 100% N

, but this is not always

practicable. Provided specimens are not unduly large,

they can be placed in a semisolid transport medium,

such as Cary-Blair medium (0.16% agar), or directly

into a campylobacter-selective broth, each containing

either FBP or sodium bisulfite 0.01%. The choice of

medium may be critical, and it is often better to use a

highly selective formulation, as campylobacters do

not compete well with other microorganisms. The

choice will be influenced by the nature of the sample,

the physical state of the target organisms, and the

time likely to elapse before cultures are set up.

0010 Milk and liquid foods should be held refrigerated

after adding sodium bisulfite 0.01% and either

sodium thioglycollate 0.15% or 100% N

. Under

these conditions there is little loss of viability over

several days, but the sooner specimens are cultured

the better.

Enrichment Techniques

0011Campylobacters that have been frozen, chilled (4



C),

or subjected to mild heating become sublethally in-

jured. This is manifested by increased susceptibility

to antibiotics (notably rifampicin and polymyxin),

deoxycholate, oxygen radicals such as peroxides,

and high incubation temperatures. This susceptibility

is thought to be due to damage to the outer membrane

of the bacterial cell and it can significantly reduce the

efficacy of detection by culture.

0012Thus the first stage of an isolation procedure is

designed to allow the organisms time to recover.

Ideally this is done in a nonselective broth incubated

at 37



C. This is feasible with samples such as water

containing few competing flora, and in which cam-

pylobacters are often severely injured. However, for

samples such as chicken, preincubation in nonselec-

tive media often results in a reduced isolation rate

because the high numbers of competing flora over-

whelm Campylobacter. Given the unpredictability of

bacterial contamination levels, it is better to use se-

lective media for the routine examination of food,

water, and environmental samples. The broth should

be at about room temperature when inoculated, and

if the volume is large, incubation is best done in a

water bath.

0013In choosing a liquid-selective medium it is import-

ant to take one that is able to suppress the growth of

competing flora adequately, particularly Pseudomo-

nas and Proteus spp. The choice will depend partly on

the type of sample being examined, as some of the

many available formulae perform better with some

materials than others. A good all-round highly select-

ive medium is Exeter broth (Table 1).

0014Various protocols have been laid down for incuba-

tion procedures. In general, maximum sensitivity can

tbl0001Table 1 Formula for Exeter campylobacter-selective

enrichU

ment broth (and agar)

Nutrient broth

Sodium metabisulfite 0.25 g

Sodium pyruvate 0.25 g

Ferrous sulfate (7.H

O) 0.25 g

Polymyxin 2500 IU

Rifampicin 5 mg

Trimethoprim 10 mg

Cefoperazone 15 mg

Amphotericin 2 mg

Lysed horse blood 50 ml

(New Zealand agar

15 g)

Nutrient broth no. 2 (CM67, Oxoid Ltd, Basingstoke, UK) in original

formula.

Commercially available as MAST SV61 Campylobacter growth

supplement.

Commercially available as MAST SV59 Campylobacter-selective

supplement.

Only for solid plating medium.

CAMPYLOBACTER

/Detection 787

be attained by initial incubation at 37



C for 18 h

followed by incubation at 42–43



C for 30 h. This

latter period can be extended for a further 24 h, and

with some lightly contaminated samples the use of

this extension has been shown to improve isolation

rates. With highly selective media like Exeter broth it

is possible to incubate samples at 37



C throughout.

In general, as large a volume of broth as is practicable

should be used in order to accommodate as much of

the sample as possible; a minimum of 25 g in 225 ml

broth is recommended.

0015 For liquid samples such as milk, it may be con-

venient to add the sample to an equal volume of

double-strength medium. For maximum sensitivity,

however, it is necessary to examine large volumes

(around 200 ml) and this can present problems.

Alternative methods of testing large volumes are to

culture gauze or cotton wool pads through which

the milk has been filtered, or to culture centrifuged

deposits.

0016 It is generally acceptable to incubate fluid cultures

in closed vessels containing air. Slight increases in

sensitivity can be attained by the use of Erlenmeyer

flasks with stoppered side-arms, so that air can be

partially extracted and replaced with a mixture of

10% carbon dioxide, 10% hydrogen, and 80% nitro-

gen. Best results are obtained if there is a constant

flow of gas mixture with agitation of the broth.

Subculture to Agar Plates

0017 Mature enrichment cultures are subcultured on a

campylobacter-selective agar. There are numerous

formulae, but either charcoal, cefoperazone, deoxy-

cholate (CCDA) or Exeter agars are recommended.

Hydrogen peroxide and other potentially toxic

oxygen metabolites can accumulate in agar even if

the plates are stored in the dark under refrigeration.

It has been shown that these compounds act synergi-

cally with antibiotics, such as rifampicin, to inhibit

campylobacter growth severely. Thus for maximum

sensitivity it is important to use fresh plates and

include FBP supplement in the agar, even if blood is

also included.

0018 Plates are incubated at 42–43



C in a microaerobic

atmosphere containing 5–10% oxygen and prefer-

ably some hydrogen. If cylinder gases are available,

the easiest method is to extract two-thirds of the air

from a closed container, such as an anaerobic jar

(without catalyst), and replace it with a mixture of

10% carbon dioxide, 10% hydrogen, and 80% nitro-

gen. If there is no cylinder gas, an anaerobic-type gas-

generating envelope can be used, and the jar partially

evacuated after closure. Alternatively, special gas-

generating envelopes for campylobacters are com-

mercially available for use in jars with a catalyst.

0019Growth is usually visible after 24 h, but occasional

strains do not appear until incubation has been main-

tained for 48 h.

0020The foregoing protocols are designed to detect the

main causes of campylobacter enteritis, namely

C. jejuni and C. coli (they will also detect C. lari).

Other species of campylobacter and related bacteria,

such as C. uppsaliensis, C. hyointestinalis, and Arco-

bacter butzleri, which have been implicated to a lesser

degree, are unlikely to be detected. Those wishing

to isolate these bacteria, for research or whatever

reason, must use special selective media incubated at



C rather than 42



C. Alteratively, nonselective

media may be used in conjunction with membrane

filters placed on the agar.

Fecal Indicator Bacteria and Campylobacters

0021It will be evident from the foregoing account that

the culture of campylobacters from food is time-

consuming and costly, especially if regular monitor-

ing is undertaken. Campylobacters are rarely found in

the absence of fecal bacteria, so for processed foods it

is reasonable to screen for the latter rather than look

for campylobacters. Most raw meats have fecal coli-

forms on them, and it must be assumed they also have

campylobacters. In short, it pays to think carefully

about the value of screening for campylobacters

before undertaking a monitoring program; it could

be unproductive and uneconomic.

Identification

0022In general, most Campylobacter colonies are typically

flat, effuse, and wet-looking, although other morpho-

types can occur. Identity is confirmed by a positive

oxidase reaction and the presence of characteristic

motile, spiral, or S-shaped Gram-negative organisms

in wet preparations and Gram-stained smears. Add-

itional basic identification tests are shown in Table 2.

Sets of these tests are available from commercial

sources and one includes simple resistogram typing.

Latex agglutination tests for identification are also

available commercially, but they need careful assess-

ment. Molecular methods that depend on the analysis

of DNA fragments can perform well in identification

tests, but they tend to be too complex for general use.

In choosing a test appropriate to one’s needs it is

important to know whether it discriminates between

groups of species, single species, or strains within a

species.

0023Meat samples, especially chicken meats, are likely

to carry Arcobacter spp. These bacteria closely resem-

ble Campylobacter spp. on agar plates. Arcobacter

spp. can be distinguished by their ability to grow in

air at 25



C(Table 2). Not all Arcobacter spp. grow at



788

CAMPYLOBACTER

/Detection

Typing

0024 Serotyping on the basis of heat-stable lipopolysac-

charide antigens (Penner system) and heat-labile

flagellar and outer-membrane protein antigens (Lior

system) is the main typing method in current use.

There are several hundred designated serotypes, but

only a limited number are found frequently. The dis-

criminatory power of serotyping can be enhanced by

the parallel use of biotyping and/or phage typing.

Typing facilities are only available at reference

laboratories.

0025 In recent years a plethora of molecular-typing

methods have appeared based on the analysis of frag-

ments of DNA split by specific enzymes. Their

discriminatory powers and complexity vary widely.

Some are simple enough for wide application, but all

suffer from a lack of standardization. Until this prob-

lem is resolved, serotyping, supplemented with phage

typing, remains the basic typing method.

Detection in Food by Noncultural Methods

0026 Immunological methods that make use of high-

affinity monoclonal antibodies were the first noncul-

tural methods to be used for the direct detection of

campylobacters. The antibody/bacterial antigen reac-

tion was detected by latex agglutination or enzyme-

linked immunosorbent assay (ELISA). Work on these

techniques was largely foresaken in favor of molecu-

lar methods, in which fragments of DNA specific to

the bacterium are recognized by specific probes and

then amplified by PCR. A sensitivity of 3–15 C. jejuni

cells in 100 ml water and 3 g

1

has been claimed.

These methods work better with samples that do

not contain an excess of other bacteria or biological

material, but they have recently been made to work

with feces. The main problem is that they need spe-

cialized skills and reagents. False-positive results are

likely unless scrupulous care is taken to avoid con-

tamination with DNA. These methods are likely to

come into their own as they become refined and easier

to use.

Detection in Suspected Food Poisoning

0027Outbreaks of campylobacter enteritis usually come to

light through the recognition of a sudden excess of

campylobacter isolations in a clinical laboratory, or,

less often, by the recognition of an excess of diarrhea

in a community. Either way the laboratory plays a key

role, as the infection cannot be diagnosed clinically.

Unfortunately, outbreak investigations are hampered

by the long time that elapses between food consump-

tion and awareness of an outbreak: the average

incubation period is 3 days; people tend not to

seek medical attention until they have been ill for

several days; sampling, testing, and reporting may

take 2–3 days; and several more days may pass before

someone realizes that cases are epidemiologically

connected. Thus, the investigation may only start

2 weeks or more after ingestion of the food, long

after suspect items have been discarded. Even if

foods are available, the vulnerability of campylo-

bacters mitigates against their survival in detectable

numbers. (See Food Poisoning: Tracing Origins and

Testing.)

0028For the above reasons reliance must often be placed

on statistical associations of infection with foods

eaten. Such evidence can be powerful and prove

beyond all reasonable doubt that a particular food

was the vehicle of infection. Protocols for investigat-

ing such outbreaks can be complex and require close

cooperation between community doctors, public

health workers, microbiologists, veterinarians, and

food producers. The prime essential is to have all

efforts directed and coordinated by one person.

See also: Campylobacter: Properties and Occurrence;

Campylobacteriosis; Food Poisoning: Tracing Origins

and Testing

Further Reading

Advisory Committee on the Microbiological Safety of Food

(1999) Report on Microbial Antibiotic Resistance in

Relation to Food Safety. London: Stationery Office.

tbl0002 Table 2 Basic differential characters of campylobacters likely to be found in food

Species Growth at 25



C Hippurate hydrolysis Indoxylacetate hydrolysis Sensitivities

Nalidixic acid Cephalothin

C. jejuni þ þ SR

C. coli  þ SR

C. lari   RR

C. fetus þ  RS

Arcobacter spp. þ

þ SR

, negative; þ, positive; R, resistant (no zone of inhibition to 30 mg disk); S, sensitive (any zone of inhibition to 30 mg disk).

Growth in air.

CAMPYLOBACTER

/Detection 789

Corry JEL, Post DE, Colin P and Laisney MJ (1995) Culture

media for the isolation of campylobacters. International

Journal of Food Microbiology 26: 43–76.

Hurtado A and Owen RJ (1997) A molecular scheme based

on 23S rRNA gene polymorphisms for rapid identifica-

tion of Campylobacter and Arcobacter species. Journal

of Clinical Microbiology 35: 2401–2404.

Johnson LG and Murano EA (1999) Comparison of three

protocols for the isolation of Arcobacter from poultry.

Journal of Food Protection 62: 610–614.

Mason MJ, Humphrey TJ and Martin KW (1999) Isolation

of sublethally injured campylobacters from poultry and

water sources. British Journal of Biomedical Science 56:

2–5.

Nachamkin I and Skirrow MB (1998) Campylobacter,

Arcobacter, and Helicobacter. In: Collier L, Balows A

and Sussman M (eds) Topley and Wilson’s Microbiology

and Microbial Infections, 9th edn, vol. 2, pp. 1237–

1256. London: Edward Arnold.

Nachamkin I, Engberg J and Aerestrup FM (2000) Diagno-

sis and antimicrobial susceptibility of Campylobacter

species. In: Nachamkin I and Blaser MJ (eds) Campylo-

bacter, 2nd edn, pp. 45–66. Washington DC, ASM Press.

Owen RJ (1995) Update on epidemiological typing of Cam-

pylobacter. PHLS Microbiology Digest 12: 2–6.

Owen RJ, Lorenz E and Gibson J (1997) Application of the

Mast resistotyping scheme to Campylobacter jejuni and

C. coli. Journal of Medical Microbiology 46: 34–38.

Roberts D, Hooper W and Greenwood M (eds) (1995)

Practical Food Microbiology, 2nd edn. London: Public

Health Laboratory Service.

Waage AS, Vardund T, Lund V and Kapperud G (1999)

Detection of small numbers of Campylobacter jejuni and

Campylobacter coli cells in environmental water, sewage,

and food samples by a seminested PCR assay. Applied and

Environmental Microbiology 65: 1636–1643.

Campylobacteriosis

M B Skirrow, Gloucestershire Royal Hospital,

Gloucester, UK

Introduction

0001 Campylobacteriosis, or Campylobacter enteritis, is

an infection of the intestines manifest by acute

diarrhea and abdominal pain. It is the most frequently

reported form of infective diarrhea in the human

population in most industrialized nations. Although

the illness seldom lasts more than a few days,

occasional patients develop complications, such as

reactive arthritis or Guillain–Barre

syndrome (GBS),

a serious neurological disorder that can result in

permanent disability or even death. The burden of

campylobacteriosis on society in terms of health

care, economic costs, and suffering is immense. This

article describes the clinical manifestations, path-

ology, and treatment of the disease, and ends by

considering options for its prevention and control.

There are many approaches to control, but ultimately

the only one that will have lasting impact is the con-

trol of infection in food-producing animals, especially

broiler chickens.

Clinical Features

0002Campylobacter enteritis is caused mainly by Cam-

pylobacter jejuni and C. coli (See Campylobacter:

Properties and Occurrence), but before describing

the disease due to these organisms, brief mention is

made of an uncommon low-grade septicemic form of

infection known as systemic campylobacteriosis,

usually caused by C. fetus. Although blood stream

invasion by C. fetus may arise from intestinal colon-

ization, diarrhea is not a common feature. This form

of infection is limited to patients with disease of the

immune system, cancer, or some other chronic disease

compromising their immunity. It is of minor import-

ance relative to Campylobacter enteritis, but it earns

a place here because C. fetus infection has been ac-

quired by eating raw calves’ liver. C. fetus is a

common inhabitant of the intestinal tract of sheep

and cattle, in which it may cause septic abortion.

0003Campylobacter enteritis is an acute self-limiting

diarrheal disease clinically indistinguishable from Sal-

monella enteritis, although minor differences become

apparent when groups of patients are compared.

0004Infection can be established with as few as 500

organisms. The average incubation period is 3 days

(range 1–7 days). In most patients the illness starts

with abdominal pain and diarrhea, but in about one-

third of patients there is an influenza-like prodrome

of malaise, headache, and fever, sometimes with

rigors, for a period ranging from a few hours to a

day or so before the onset of gastrointestinal symp-

toms. Profuse diarrhea lasts for 2–3 days and is

almost invariably accompanied by abdominal pain,

which is sometimes severe enough to simulate acute

appendicitis and cause some patients to undergo

emergency surgery. Occasionally there is genuine ap-

pendicitis. Children sometimes have abdominal pain

without diarrhea. Surveys of patients affected in com-

munity outbreaks show that, on average, about 50%

have fever, 40% myalgia, 8% rigors, 14% frank

blood in their stools, but only 15% vomit, even

though nausea is common.

0005Some patients present with acute colitis that is dif-

ficult to distinguish from an acute attack of idiopathic

ulcerative colitis (inflammatory bowel disease). Acute

790

CAMPYLOBACTER

/Campylobacteriosis

complications are rare but include intestinal haemor-

rhage, toxic megacolon, hemolytic–uremic syndrome,

pancreatitis, and septic abortion.

0006 After a few days the diarrhea eases and about 80%

of patients recover within a week, irrespective of any

treatment they may receive. Minor relapses have been

reported in about 20% of patients after a day or two

without diarrhea.

0007 Young and middle-aged adults seem to be most

severely affected by the infection. Unlike salmonel-

losis, Campylobacter enteritis in infants is often mild,

and although infection in old people tends to be more

invasive, it is seldom dangerous. Death is rare and

virtually limited to frail patients debilitated from

other causes.

Late Complications

0008 There are two late complications that typically arise

1–2 weeks after the onset of illness: reactive arthritis

and GBS.

Reactive Arthritis

0009 Reactive (aseptic) arthritis affects about 1% of pa-

tients, particularly those possessing the human leuko-

cyte antigen (HLA) B27. The ankles, knees, wrists,

and the small joints of the hands are most frequently

affected, often in migratory fashion. It can cause

painful debility lasting for several months, but it is

ultimately benign. Clinically it is the same as the

reactive arthritis that sometimes follows other forms

of acute bacterial enteritis.

Guillain–Barre

Syndrome

0010 Another name for GBS is postinfective polyneuropathy.

It is a serious, though fortunately rare complication

causing paralysis that does not always resolve com-

pletely. Severely affected patients develop respiratory

paralysis and have to be nursed on a ventilator. Surveys

indicate that Campylobacter infection is the antecedent

event in 14–41% of patients with GBS – it is the most

commonly identified trigger for the disease.

0011 The mechanism of this distressing condition, in

which the myelin in peripheral nerves becomes lost

or damaged, is thought to be immunological. Certain

C. jejuni strains are particularly associated with GBS,

and some have been found to possess cell wall epi-

topes that cross-react with proteins in peripheral

nerve myelin. It is believed that this triggers immuno-

logical attack and destruction of the myelin.

Convalescent Excretion

0012 Excretion of Campylobacter in feces falls off expo-

nentially after illness. About 50% of patients are

culture-negative after 3 weeks, and virtually all are

negative after 3 months. Long-term carriage is un-

known except in patients with severe immune defi-

ciency, such as hypogammaglobulinemia or acquired

immune deficiency syndrome (AIDS). Spread of infec-

tion from a healthy excreter is a remote risk. In the

case of food handlers, provided they have formed

stools there is no need to exclude them from work.

0013The basic features of Campylobacter enteritis are

summarized in Table 1.

Pathology

0014The essential lesion in Campylobacter enteritis is

an acute inflammation of the jejunum and small

intestine, which progresses to the cecum, colon, and

rectum. The histopathology of the intestinal mucosa

is one of acute inflammatory cellular infiltration in-

distinguishable from that seen in Salmonella, Shi-

gella, or other acute bacterial infections of the gut.

The terminal ileum and cecum are often particularly

affected, and it is this feature that causes the

symptoms that mimic acute appendicitis.

0015Campylobacter are invasive and may be present in

the blood stream at the onset of illness, as indicated

by the high fever and rigors experienced by some

patients. Unlike C. fetus, C. jejuni and C. coli are

sensitive to the natural killing power of normal

serum, so any bacteremia is likely to be transient

and hence seldom detected in blood cultures (bacter-

emia reported in only 0.15% of infections). Regional

lymph nodes are often enlarged and inflamed. A chol-

era-like enterotoxin and at least one cytotoxin are

produced in modest quantities by many strains of C.

jejuni and C. coli, but the role played by these in

pathogenesis is unclear.

Immunity

0016Circulating (humoral) antibodies are produced within

a few days of illness and for at least several months

patients are refractory to reinfection with the same

strain. People regularly exposed to infection develop

tbl0001Table 1 Basic features of Campylobacter enteritis

Feature Duration and details

Incubation period 3 days (range 1–7 days)

Main symptoms Diarrhea, abdominal pain, fever

Mean duration of illness

Incapacity 3.8 days

Symptoms 14.6 days

Mean duration of fecal

Campylobacter excretion

38 days (maximum 69 days)

Exclusion from food handling Until stools formed

Figures taken from a Norwegian study of 135 sporadic cases.

CAMPYLOBACTER

/Campylobacteriosis 791

solid immunity. Children in developing countries,

where transmission rates are high, become immune

within the first 2 years or so of life, and occupation-

ally exposed groups in industrialized countries also

become immune. For example, in a milkborne out-

break of Campylobacter enteritis in the USA, 76% of

people exposed for the first time were ill, whereas no

person who habitually drank raw milk became ill.

In the UK significant amounts of Campylobacter-

specific antibody were found in 18% of veterinary as-

sistants, 36% of cattle abattoir workers, and 27–68%

of workers in poultry-processing plants, compared

with 2–5% in nonexposed adults. Infection with one

or two strains may be sufficient to give broad immun-

ity, although there are patients who have had two

attacks of Campylobacter enteritis several months

apart; in each case the second infection has been

with a different strain. It is not known how long

immunity lasts, but regular exposure is probably

necessary for its maintenance.

Treatment

0017 As Campylobacter enteritis almost always resolves

spontaneously, treatment is primarily symptomatic

and supportive. The most important element, as

with all forms of acute diarrhea, is the correction of

dehydration and electrolyte loss, particularly in

infants and old people, who are least able to do this

of their own accord. In many cases simply getting

patients to increase their fluid intake with assorted

drinks is sufficient, but giving a balanced electrolyte

preparation such as Dioralyte is ideal.

0018 Antimicrobial therapy is effective if given within a

day or two of the onset of illness, but a bacteriological

diagnosis has seldom been made at this stage. If a

patient is still suffering from acute symptoms when

a positive report is received, antimicrobial therapy is

justified. Erythromycin is the antibiotic of choice for

both children and adults. In patients with severe diar-

rheal illness, who might be put at risk if treatment

were delayed until a bacteriological report was avail-

able, there is a case for treating empirically with an

antimicrobial agent effective against the common

enteropathogenic bacteria. Ciprofloxacin, or an

equivalent quinolone drug, was once the ideal agent

here, and it still may be in some places. Unfortunately,

in recent years resistance rates in Campylobacter (as

well as Salmonella) have soared to around 50% in

some European countries, so that its use has been

drastically compromised. This is almost certainly a

result of the widespread use of quinolones in poultry.

0019 Fortunately erythromycin resistance is less of a

problem. In industrialized countries resistance has

remained at about 1–5% of strains, but higher rates

have been found in some developing countries,

notably 65% in Thailand. Erythromycin resistance

is much more common in C. coli than C. jejuni,

probably due to the use of tylosin, a similar macrolide

antibiotic, in pig rearing.

Prevention

0020Basic measures for the prevention of any communic-

able intestinal infection apply equally to Campylo-

bacter enteritis. These include the treatment and safe

disposal of sewage, the provision of potable water, the

pasteurization or equivalent heat treatment of milk,

and the general hygienic processing and handling

of food. An important aspect of the prevention of

Campylobacter infection is the interruption of trans-

mission from food-producing animals, particularly

poultry, to the final food product. Each of these is

now considered.

Sewage Disposal

0021Campylobacter are plentiful in raw sewage. The dis-

charge of untreated sewage is undesirable as it helps

to maintain the Campylobacter population in the

environment. Conventional sewage treatment is ef-

fective in eliminating Campylobacter. In one study

over 78% were removed after primary sedimentation,

and less than 0.1% remained in the final effluent.

Water Purification

0022Campylobacter are ubiquitous in natural surface

waters, including sea water. They are capable of sur-

viving for several weeks in cold water (below 15



C).

Survival is increased in waters that have an autoch-

thonous microflora. Campylobacter also appear to be

capable of forming viable but nonculturable forms,

which are alleged to survive for several months or

longer. However, the potential role of such dormant

cells in the epidemiology of Campylobacter has

yet to be established. Conventional treatments are

fully adequate for removing Campylobacter, which

are generally more sensitive to chlorine and other

disinfecting agents than Escherichia coli. Contact

with monochloramine 1.0 mg l

1

for 15 min or

free chlorine 0.1 mg l

1

for 5 min causes more than

99% inactivation. Campylobacter are also sensitive

to ultraviolet light and are destroyed by protocols

designed to kill E. coli.

0023Major community outbreaks of Campylobacter

enteritis have been caused by the distribution of

unchlorinated or inadequately chlorinated water (See

Campylobacter: Properties and Occurrence), which

serves to emphasize the importance of proper treatment.

This applies equally to remote oligotrophic lakes and

surface waters, which become contaminated from wild

792

CAMPYLOBACTER

/Campylobacteriosis

birds and other animals. A number of outbreaks have

arisen as a result of the failure of outdated, overloaded,

or inadequately maintained water works or distribution

systems. (See Water Supplies: Water Treatment.)

Heat Treatment of Milk

0024 Pasteurization and other orthodox treatment pro-

cesses are fully effective in destroying Campylobacter.

Despite this, milkborne outbreaks of infection regu-

larly occur, even where it is illegal to sell raw milk

to the public. Some of the largest outbreaks of Cam-

pylobacter enteritis on record have been milkborne,

mostly from the distribution of raw milk, but a few

of them from ostensibly pasteurized milk. Thus,

although compulsory pasteurization is a highly

desirable goal, it is unlikely to eliminate all risks of

milkborne infection. Bad design, malfunctioning of

machinery, or those running the machinery, the diffi-

culty of designing satisfactory small pasteurizing

units at reasonable cost are all factors that need at-

tention in order to minimize risks. Electricity supply

failures putting pasteurizing machinery out of action

and bad weather preventing the delivery of milk to

central pasteurizing plants have also been precipitat-

ing factors in outbreaks of milkborne infection.

Food Hygiene

0025 Measures taken to maintain good hygiene and food-

handling practice in restaurants and other catering

establishments are fundamental to the prevention of

Campylobacter enteritis. Much infection is believed

to be transmitted through the cross-contamination

of cooked or ready-to-eat foods, such as bread and

salads, from raw poultry or other raw meats. The

separation of raw from cooked foods and the use of

dedicated equipment for each, such as chopping

boards, mixers, knives, and other utensils, is the

single most important principle to be observed. If

raw meats cannot be stored separately they should

always be placed on a bottom shelf so they cannot

drip juices on to other foods.

0026 Raw poultry should be handled as little as possible;

handling and even washing carcasses only spreads

organisms around work areas. The discipline of

washing hands after touching raw meats of any sort

should be rigorously observed.

0027 It has been shown that Campylobacter can be isol-

ated from the flesh of chicken carcasses even when the

surface has been disinfected by immersion in boiling

water. Chicken muscle affords the organism some

protection from the effects of heat and this is the

probable explanation for the implication of barbe-

cued chicken in outbreaks of Campylobacter enter-

itis. It is therefore particularly important that chicken

and other poultry meat is properly cooked.

0028These rules must be taught to all professional food

handlers and it is the responsibility of health author-

ities to see that correct instruction is carried out and

maintained to satisfactory standards. Analysis of out-

breaks shows that many arose through ignorance of

these basic rules. (See Poultry: Chicken.)

Control of

Campylobacter

in Poultry

0029Elimination of Campylobacter from food-producing

animals is clearly impracticable owing to the wide

natural distribution of the organisms. Yet there

are ways of reducing colonization in farm animals,

especially in poultry.

0030Campylobacter colonization in broiler chicken

flocks does not usually appear until 2 weeks or more

after hatching. This is taken to indicate horizontal

transmission of Campylobacter from the environ-

ment either within or outside the broiler house.

Thus there is the possibility of preventing coloniza-

tion, or at least extending the Campylobacter-free

period, by improving hygienic practice among

broiler-house attendants and proofing houses against

intrusion by birds and rodents. Such interventions

have met with partial success, notably in Scandinavia

and The Netherlands.

0031In some cases water has been shown to be a crucial

factor in promoting colonization. Many broiler

houses are served by unchlorinated private borehole

supplies that are suspect. Even in mains-supplied

houses Campylobacter can become established in dis-

tribution systems beyond header tanks. Experimental

interventions, in which header tanks and distribution

pipework have been thoroughly cleaned and disin-

fected, have been followed by dramatic falls in colon-

ization rates in the broilers. Unfortunately such

measures are difficult to sustain under agricultural

conditions and further research is needed.

0032It is generally believed that, unlike Salmonella in-

fection, vertical transmission of Campylobacter from

parent flocks does not occur. This view has been

challenged by the results of a 5-year study in the

UK, in which the distribution of C. jejuni serotypes

in broiler flocks supplied with day-old chicks from

two hatcheries pointed to vertical rather than

horizontal transmission. C. jejuni readily survives in

embryonated eggs. If vertical transmission is con-

firmed, there is the possibility of preventing Cam-

pylobacter colonization of broilers by ensuring that

breeder flocks are kept free from infection.

0033The principle of competitive exclusion, in which

normal intestinal flora is artificially established in

newly hatched chicks in order to exclude pathogens

such as Salmonella, is not applicable to Campylo-

bacter control, as the intestinal flora has already

become established by the time Campylobacter

CAMPYLOBACTER

/Campylobacteriosis 793

make their appearance. An experimental oral vaccine

has been used with some success in broiler chicken

flocks. This is a sound approach that could have

major benefit.

0034 The total elimination of Campylobacter from

broiler flocks is probably not practicable, but redu-

cing the extent of colonization may be sufficient to

curtail transmission to the human population. The

logistics, precise methods, and costs of such measures

have yet to be worked out, but they are urgently

needed if there is to be any hope of reducing the

present unacceptable burden of the disease. These

measures need to be studied in relation to the prob-

lems of cross-contamination during the mechanical

processing of poultry, which are discussed elsewhere

(See Campylobacter: Properties and Occurrence.)

0035 Terminal irradiation of dressed poultry is an option

that removes all pathogens, including Campylo-

bacter, but there are problems with this, not least

public acceptability. (See Irradiation of Foods: Basic

Principles.)

0036 Waste disposal from poultry farms An added ad-

vantage of controlling Campylobacter colonization

of poultry is that fewer bacteria would be returned

to the environment and to surface waters. Heavily

colonized flocks have a prodigious output of Cam-

pylobacter that are likely to be recycled in farm

stock via surface water and wild or feral animals

that are closely associated with farms, such as

magpies, jackdaws, starlings, pigeons, sparrows,

rats, and mice. Cattle with access to surface water

are commonly colonized, whereas those with access

only to mains water have been found to be free of

Campylobacter.

Public Education

0037 It has been said that if everyone handled their foods

properly, foodborne Campylobacter enteritis would

virtually disappear. This is probably true, but it is an

unrealistic expectation. Yet much could be done to

improve matters. Surveys to assess public knowledge

of the rudiments of food hygiene have revealed abys-

mal ignorance. It should not be difficult to remedy

this. Even to impart the simplest facts about handling

poultry could have an impact that far outweighs the

effort – and it would help control salmonellosis as

well as Campylobacter enteritis. Television is the

most influential medium and a substantial impact

could be made by broadcasting high-quality enter-

taining yet informative spot ‘advertisements.’

The understandable fears of the poultry and retail

industries could be allayed by inviting their participa-

tion and ensuring that the content of such spots

was sensibly balanced. With appropriate professional

skills, it could even be turned to their advantage.

Public moneys used to fund such a venture should

be amply offset by the savings from infections

prevented.

See also: Campylobacter: Properties and Occurrence;

Irradiation of Foods: Basic Principles; Poultry: Chicken;

Water Supplies: Water Treatment