Growth and survival characteristics of Campylobacter jejuni in liquid egg

Survival of Campylobacter jejuni on various fresh produce

The survival of seven human and two chicken Campylobacter jejuni strains, with known Penner heat-stable (HS) serotypes and pulsed-field gel electrophoresis (PFGE) genotypes, was investigated on fresh-cut iceberg lettuce. In addition, the survival of four selected C. jejuni strains was assessed on cantaloupe pieces, cucumber slices, grated carrot and strawberries. Fresh produce was inoculated with 10(5) to 10(7) colony-forming units (CFU) of C. jejuni per gram, and the bacterium was enumerated using standard procedures after sample storage at 7 and 21 degrees C for 24, 48 and 72 h. The absolute values of the slopes (death rates) of the survival curves (log(10) CFU/g versus time) were calculated and compared. At 7 degrees C, the mean death rates (day(-1)) were 0.44 on cantaloupe, 0.41 on cucumber slices, 0.43 on grated carrot, 0.59 on iceberg lettuce and 1.02 on strawberries. The corresponding death rates (day(-1)) at 21 degrees C were 1.52, 1.55, 2.61, 1.39 and 8.74. The death rate of C. jejuni on strawberries (pH 3.4) was significantly (P<0.05) higher than on other produce. Moreover, the death rate at 21 degrees C as compared with 7 degrees C was significantly higher (P<0.05). Minor differences were observed in the survival of different C. jejuni strains. Our results suggest that after contamination of fresh produce, including strawberries, C. jejuni may survive sufficiently long to pose a risk to the consumer.

Detection and survival of Campylobacter in chicken eggs

AIMS

Campylobacter jejuni, a food-borne human pathogen, is widespread in poultry; however, the sources of infection and modes of transmission of this organism on chicken farms are not well understood. The objective of this study was to determine if vertical transmission of C. jejuni occurs via eggs.

METHODS AND RESULTS

Using a temperature differential method, it was shown that Campylobacter had limited ability to penetrate the eggshell. When C. jejuni was directly inoculated into the egg yolk and the eggs were stored at 18 degrees C, the organism was able to survive for up to 14 days. However, viability of C. jejuni was dramatically shortened when injected into the albumen or the air sac. When freshly laid eggs from Campylobacter-inoculated specific pathogen-free (SPF) layers were tested, C. jejuni-contamination was detected in three of 65 pooled whole eggs (5-10 eggs in each pool) via culture and PCR. However, the organism was not detected from any of the 800 eggs (80 pools), collected from the same SPF flock, but kept at 18 degrees C for 7 days before testing. Likewise, Campylobacter was not recovered from any of 500 fresh eggs obtained from commercial broiler-breeder flocks that were actively shedding Campylobacter in faeces. Also, none of the 1000 eggs from broiler breeders obtained from a commercial hatchery were positive for Campylobacter.

CONCLUSIONS

These results suggest that vertical transmission of C. jejuni through the egg is probably a rare event and does not play a major role in the introduction of Campylobacter to chicken flocks.

SIGNIFICANCE AND IMPACT OF THE STUDY

Control of Campylobacter transmission to chicken flocks should focus on sources of infection that are not related to eggs.

Analysis of distribution of Campylobacter jejuni and Campylobacter coli in broilers by using restriction fragment length polymorphism of flagellin gene

The incidence of Campylobacter jejuni and Campylobacter coli in broiler farms was 33.9% (19/56). C. jejuni-positive flocks accounted for 20.0% (17/85) and C. coli-positive ones was 4.7% (4/85). There were 14 patterns (fla type) of restriction fragment length polymorphism (RFLP) of flagellin A gene among these 22 strains of C. jejuni and C. coli including the standard strain C. jejuni ATCC 33560. Different fla types of Campylobacter were isolated from broilers in different growing cycles on the same farms. Four strains of C. jejuni were isolated from four breeder farms and four fla types of C. jejuni were detected from their progenies reared on growing farms. Three fla types of C. jejuni detected from the progenies were different from those of each breeder. Also, the other three fla types of C. jejuni were detected from different progenies of each growing farm during the next growing cycle. These findings indicate that the RFLP analysis may contribute to epidemiological studies of C. jejuni and C. coli contamination of broilers and suggest the risk of contamination with different types of Campylobacter in every growing cycle of broilers on the farm even on the same farm. They also supported that there was little likeliness of the vertical transmission of C. jejuni and C. coli from breeders to broilers.

The response of Campylobacter jejuni and Campylobacter coli in the Sydney rock oyster (Crassostrea commercialis), during depuration and storage

Sydney Rock Oysters, when allowed to feed in waters containing approximately 10(4) cfu of Campylobacter cells per ml, concentrated between 10(2) and 10(3) cfu of the organism per g of oyster tissue, within 1 h. When these contaminated oysters were subjected to depuration, they were effectively cleaned in 48 h. The survival of Campylobacter jejuni and Campylobacter coli was also investigated. Oysters contaminated by feeding and injection were processed as half shells and bottled oysters and were held at 3 and 10 degrees C. Half shells were also stored at -20 to -24 degrees C. At all these temperatures the organism survived for periods varying between 8 to 14 days and in oysters contaminated by feeding, the survival was substantially greater. Survival was better at 3 than at 10 degrees C in half-shelled oysters. Campylobacter survived better in bottled oysters than in half shells stored at the same temperature. In frozen half shelled oysters previously contaminated by feeding, the organisms were viable for months. In contaminated unopened oysters stored at 20 and 30 degrees C, C. jejuni and C. coli failed to multiply as expected. They survived for periods varying from 2 to 9 days.

Incidence of Campylobacter jejuni in processed egg products

Egg samples were obtained from two commercial egg-processing facilities to determine if Campylobacter jejuni could be isolated from the raw product or from further-processed egg products intended for human consumption. No C. jejuni were detected in any of the egg or egg-product samples or from water samples collected from the overflow of the egg washer. Campylobacter jejuni was recovered from all control samples, which had been inoculated at the plants. These findings suggest that properly processed egg products are an extremely unlikely source of C. jejuni contamination.

Campylobacter jejuni in broilers: the role of vertical transmission

The role of broiler eggs in the transmission of Campylobacter jejuni to broiler grow-out flocks was investigated. Six breeder flocks supplying broiler eggs to hatcheries were examined for cloacal carriage of C. jejuni. Of 240 birds tested, 178 (74%) were C. jejuni-positive. Eggs from these birds examined for C. jejuni penetration of the egg shell indicated that 185 of 187 were campylobacter-free. Eggs from breeder flocks of unknown C. jejuni status were also examined for C. jejuni shell penetration. C. jejuni was not isolated from 142 eggs examined. A further 193 hatchery eggs incubated and hatched in the laboratory were campylobacter-free. Six farms containing the progeny of C. jejuni-positive breeder flocks were monitored. Eight hundred and forty birds from 14 flocks in these grow-out farms were campylobacter-free during their 6-week grow-out period. Experimental egg-penetration studies indicated that C. jejuni transmission via the egg is not easily effected. Of 257 eggs surface-challenged with C. jejuni, 162 hatched; all were campylobacter-free. Of 167 eggs injected with C. jejuni, 12 hatched; 2 of these were colonized with C. jejuni. Our data do not support a role for vertical transmission of C. jejuni in commercial broiler production.