Occurrence of Campylobacter jejuni and Campylobacter coli and their biotypes in beef and dairy cattle from the south of Chile.

The prevalence of Campylobacter jejuni and Campylobacter coli and their biotypes in beef and dairy cattle from the South of Chile was established. Campylobacter were statistically more prevalent among beef cattle (35.9%) than among dairy cattle (21.3%), being C. jejuni the species most frequently isolated.

The thermotolerant species (C. jejuni and C. coli) of the genus Campylobacter are zoonotic bacteria with worldwide distribution. These bacteria are the primary causative agents of diarrhea in humans in industrialized countries, and are important causes of diarrhea in developing countries (4, 8, 10, 16).

Reservoirs for C. jejuni and C. coli include cows, sheep, pigs, and other species of domestic and wild animals, all of which can be direct or indirect sources of infection for humans. C. jejuni and C. coli are carried as commensal organisms in the intestines of these animals. C. jejuni may also cause abortion in some animal species (3, 4, 6, 14, 16).

In the southern Chile, beef and dairy cattle should be considered an important reservoir for Campylobacter contamination of milk, meat, and the environment (6). Campylobacter should also be considered a veterinary problem in production animals. C. jejuni has been reported to cause enteritis in calves and bovine mastitis and C. fetus subsp. fetus is responsible for abortion and infertility in cattle (1, 14).

In Southern Chile, it has been demonstrated that free reared domestic laying hens and pet and stray dogs are reservoirs of Campylobacter, and they contaminate the environment where these domestic animals live (5, 6, 7). However, there is little information on the relevance of cows in the transmission of C. jejuni and C. coli to humans.

Beef and milk production are important in this part of Chile, and it is therefore necessary to know the prevalence of C. jejuni and C. coli in cows in this geographical area, to establish its isolation frequency, common biotypes, and to determine if there are differences between the carriage for confined dairy cows and for beef cattle raised on grass.

We studied 300 faecal swab samples collected from cows. These samples were collected at random from 220 cattle going to a slaughter house (Frival Valdivia), and from 80 confined dairy cattle from the same herd, kept indoors.

After collection, samples were transported in Cary-Blair medium (approximately 2 ml) under refrigeration for a period of no more than 18 hours. Samples were plated out on modified Skirrow agar plates (cit. 5, 6), which were incubated at 42°C for 48 hours under microaerobic conditions (6), for the isolation of thermotolerant Campylobacter species (C. jejuni and C. coli). The identification of the species was done with phenotypic tests using the API Campy® (bioMérieux. Marcy/Etoile, France.) test procedure. The biotyping was done using the method described by Lior (11) as adapted for use in our laboratory (6). Statistical evaluation was done through z test using Epidat 3.1 program (13).

Table 1 shows that 32.0% of the samples were positive for Campylobacter spp. Significant differences (p < 0.05) were found between the highest prevalence rate, observed in beef cattle (35.9%), and the lowest prevalence rate found in dairy cattle (21.3%). In all sample groups, C. jejuni was the most commonly isolated species (85 strains) with the remaining of the samples being C. coli (11 strains).

Table 1

Isolation frequency of Campylobacter jejuni and C. coli, and their biotypes in beef and dairy cattle.

			C. jejuni										C. coli
			Biotypes							Biotypes
			Type of cattle	Simples studied	Positive samples		Strains isolated		I		II		III		IV		Strains isolated		I		II
	N°	N°	%	N°	%	N°	%	N°	%	N°	%	N°	%	N°	%	N°	%	N°	%
Dairy	80	17	21.3*	15	100	9	60.0	6	40.0	0	0.0	0	0.0	2	100	1	50.0	1	50.0
Beef	220	79	35.9*	70	100	41	58.6	13	18.6	14	20	2	2.9	9	100	6	66.7	3	33.3
Total	300	96	32.0	85	100	50	58.8	19	22.4	14	16.5	2	2.4	11	100	7	63.6	4	36.4

Within dairy cattle, 15 strains of C. jejuni were found, with biotype I showing the highest prevalence (60.0%) and biotype II making up the rest (40.0%). Only two strains of C. coli were isolated in this group, corresponding one strain to biotype I and the other, to biotype II.

Seventy strains of C. jejuni were isolated from beef cattle. Biotype I was the most frequent (58.6%), followed by biotype II (18.6%), biotype III (20%) and biotype IV (2.9%).

The two biotypes described for C. coli were found, with biotype I composing 66.7% of the isolates and biotype II making up the rest (33.3%).The overall prevalence of Campylobacter spp. was 32.0%, a prevalence that is similar to reports by Fernández (8) in Chile (39.3%). A higher prevalence rate has been reported by Giacoboni et al (9) in Japan (46.7%). In addition, lower prevalence rates have been found by Cabrita et al (3) in Portugal (19.5%), and Tresierra et al (15) in Peru. These results indicate, from the epidemiological stand point that intestinal carriage may be conditioned by the environment in each place. The higher prevalence of C. jejuni in relation to C. coli is a common pattern that is found in most studies and includes samples isolated from animals and humans (6, 8, 16).

Bailey et al (2), studing 19 herds in Australia, found that Campylobacter prevalence ranged from 0%–24% for dairy cattle and 0%–52% for pasture beef cattle. Padungtod and Kaneene (12) reported that Campylobacter prevalence was 14% in dairy cows in Thailand. In the two latter studies C. jejuni was also more frequent than C. coli.

The higher prevalence of Campylobacter in beef cattle is an epidemiological event that may be associated to the environment where these cattle have been raised. While beef cattle are raised on pasture and in contact with a diverse environment, dairy cattle are kept in confinement and under better environmental hygienic conditions. A direct correlation between poor environmental hygienic conditions and a higher prevalence rate for Campylobacter was reported by Fernández et al for laying hens (5) and dogs (7).

The fact that four biotypes of C. jejuni were isolated from beef cattle while only two biotypes were found in dairy cattle is also a result of the different environmental exposure between these two types of production (5, 7). In both group of animals (beef and dairy), biotypes I and II where the most prevalent, and they also happen to be the most prevalent biotypes isolated from other animals and humans in our region (6).

Based on these results, we believe there is a need for further studies aimed at elucidating the sources of environmental contamination for beef and dairy cattle. In addition, the environment of the processing facilities for these animals and the resulting foods should also be evaluated for the presence of Campylobacter spp. to implement specific control measures designed to improve the safety of these foods.