Campylobacter jejuni

1. Campylobacter jejuni 黃顯宗

2. Campylobacter jejuni • 早期名為Vibrio fetus，屬於動物病菌，1970年中期才有乳品與水污染中毒發生 • 主要是兩種C. jejuni，C. coli及大多數中毒為前者（95%） • G-，vibriod，microaerophilic，在21%O2下不長，最適生長溫度42度，生長範圍在25~50度，菌體小，生長慢 • 禽類普遍可分離到

3. INTRODUCTION • Campylobacter could be isolated from the normal flora of barnyard animals and fowl and caused periodically diarrheal diseases. • Therefore, much of the early investigation of Campylobacter was done by the veterinary community • Originally classified in the genus Vibrio and the new genus, Campylobacter, was created by Sebald and Veron in 1963

4. Campylobacter jejuni • 培養時空氣成份是5%O2、10%CO2、85%N2 • 潛伏期2~5天，症狀：發熱，下痢，腹痛，血便 • 在美國地區發生率高，幾乎與Salmonella、Shigella相當

5. 世界食品安全趨勢 全球食品安全發展趨勢

6. INTRODUCTION • Campylobacter also caused human abortion and tissue and blood infections including septic arthritis, bacterial endocarditis, phlebitis (血栓靜脈炎), meningoencephalitis, prolonged febrile illness (發燒), stillbirth, etc. • Most of the early illnesses attributed to Campylobacter was caused by C. fetus

7. INTRODUCTION • Epidemics involving C. jejuni have been reported from both developed and underdeveloped countries and it is also one of the causative agents of traveller's diarrhea • Children in the underdeveloped countries could be asymptomatic carriers and also the leading cause of diarrhea

8. TAXONOMY AND GENERAL CHARACTERISTICS • The genus Campylobacter is composed of Gram-negative, vibroid shaped bacteria which, when examined microscopically in wet mounts, exhibit a corkscrew-like darting motility

9. Classification and Biotyping

10. Classification and Biotyping • The genus is divided initially into two groups based on the presence or absence of catalase. The catalase-negative species are generally considered to be saphrophytes • All "C. upsaliensis" strains were hippurate negative, and six of seven were susceptible to cephalothin. This new species could be a potential human pathogen associated with gastroenteritis and bacteremia in normal individuals as well as with opportunistic infections in immunocompromised patients

11. Classification and Biotyping • The catalase-positive species include C. jejuni, C. coli, and C. fetus subspecies fetus and venerealis, C. laridis and C. hyointestinalis. • Aerotolerant Campylobacter strains have also been identified from aborted porcine, ovine, and equine fetus, and DNA homology studies suggest them to be a new species.

12. Classification and Biotyping • C. jejuni and C. coli are the most common, human intestinal pathogens, although other catalase-positive species are occasionally responsible for cases of human gastroenteritis • Generally, the human intestinal pathogens (C. jejuni, C. coli) can be distinguished by their thermophilic growth properties (i.e. growth at 42C). • The non-intestinal pathogens grow at 25C, but not at 42C

13. Biotyping

14. DNase activity • The bacteria were preincubated in polymyxin B (which has been used to release the cell-associated secretory proteins, such as enterotoxins, protease, alkaline phosphatase, DNase, etc.) and suspended into the well in the DNase test agar plate (DNase agar of Difco with 0.01% toluidine blue O). A strong pink zone indicating DNA hydrolysis was seen around the well after 20 to 24 h of aerobic incubation at 37C.

15. Microaerophilism • These bacteria fail to grow aerobically in air atmospheres (i.e. 21% O2, v/v), but can be cultured successfully under microaerobic conditions in atmospheres containing 6-10% oxygen supplemented with 5% carbon dioxide, either nitrogen or hydrogen may be used to make up the difference in partial pressure

16. Microaerophilism • The microaerophilic nature of the campylobacters may be related to their sensitivity to toxic reduced forms of oxygen, such as superoxide radicals and hydrogen peroxide. Such toxic substances may be formed by photoreaction and in the presence of air.

17. Microaerophilism Light and Air

18. Microaerophilism • Addition of ferric iron, sodium metabisulphite, sodium pyruvate to brucella-based medium permitted most strains of C. jejuni to grow aerobically (i.e. at 21% oxygen) in a CO2 incubator • The addition of bovine erythrocyte superoxide dismutase (Cu/Zn enzyme) to brucella agar is even more effective in enhancing aerotolerance • Catalase (catalase and superoxide dismutase are present in the cytoplasm of catalase-positive campylobacters) also enhance aerotolerance, but to a lesser extent.

19. Microaerophilism • The chemicals added to enhance aerotolerance scavenge superoxide radicals (ferric iron binding dihydroxyphenyl compounds, ferric iron bisulphate coordination complexes) • or decompose hydrogen peroxide (e.g. pyruvate) • Addition of active superoxide dismutase, a superoxide anion scavenging enzyme, minimizes production of cocccoid forms in suspensions stored in air

20. Microaerophilism • Addition of charcoal trap for free radicals generated by photochemical oxidative mechanisms, therefore, it is recommended that media used for the primary isolation of campylobacters be stored in the dark to prevent peroxide build-up in the medium

21. Microaerophilism • Proteins involved in the oxidative stress of campylobacters have been studied. • Of the three groups of haemoglobins identified in microorganisms (single-domain globins, flavohaemoglobins and truncated globins), the last group is involved in moderating O2 flux within C. jejuni.

22. Microaerophilism • The function of the truncated haemoglobin (Ctb) encoded by C. jejuni was investigated by constructing a ctb mutant and characterizing its phenotype • Cells mutated in ctb were disadvantaged when grown under conditions of high aeration and defective in survival in air

23. Microaerophilism

24. Microaerophilism • Pathogenic bacteria experience nitrosative stress from NO generated in the host and from nitrosating species such as S-nitrosoglutathione. • The food-borne pathogen C. jejuni responds by activating gene expression from a small regulon under the control of the NO-sensitive regulator, NssR. • The NssR regulon up-regulated two hemoglobins (Cgb and Ctb) and more than 90 other genes, notably those encoding heat shock proteins and proteins involved in oxidative stress tolerance and iron metabolism/transport

25. Microaerophilism • The putative global posttranscriptional regulator csrAwas mutated in C. jejuni. • In E. coli, CsrA is involved in regulating stationary-phase metabolism, represses glycogen biosynthesis, gluconeogenesis, peptide transport, and biofilm formation. • The csrA mutant was attenuated in surviving oxidative stress.

26. Microaerophilism • In another study, the oxidative stress response after exposure to paraquat, a strong oxidising agent, was analyzed by two-dimensional protein electrophoresis and Maldi-ToF mass spectrometry • Oxidative stress and redox-related proteins were overexpressed: FldA flavodoxin and a pyruvate-flavodoxin oxidoreductase encoded by cj1476c. • No increase in SodB expression was observed. • An additional quantitative RT-PCR analysis showed an increase in katA but not in sodB expression • However, the sodB mutant was very sensitive to paraquat,

27. Morphology • Several morphology forms of C. jejuni are found in culture. Rod forms, which include spirals, S-shaped and characteristically curved cells predominate in fresh young cultures • whereas non-culturable coccoid forms occur mainly in old cultures • In addition, rods transform to coccoid forms when conditions are unfavorable for growth • Compared with stored media, production of coccoid forms was less on freshly prepared media • Addition of supplements used as detoxifying agents (ferrous sulphate, sodium metabisulphite and sodium pyruvate) minimized production of these forms on media.

28. Morphology • Viable but nonculturable • VBNC

29. Morphology

30. Growth Temperature and Heat Resistance • Optimal temperature for the growth of Campylobacter is at 42C. • C. jejuni is not a heat-stable bacterium, with low D value. • 受到基質影響 • The D value in chicken medium was higher than in peptone medium

31. Growth Temperature and Heat Resistance • D value測定方法 • Z value

32. Effects of Iron and Other Minerals • Cells grown in low-iron medium exhibited slower growth rates and altered cellular morphology • Increased numbers of longer, more filamentous forms were seen in Gram-stain smears

33. Effects of Iron and Other Minerals

34. Effects of Iron and Other Minerals • Three proteins, with apparent Mol.Wt. of 82,000, 76,000, and 74,000, were consistently present in the outer membrane of cells grown in low-iron medium • 鐵的攝取 • Siderophore • transporter

35. Plasmid Profile and Antibiotic Resistance • Serotyping, phage typing, plasmid profile and antibiotic resistance could be useful epidemiological markers • Usually high percentage of Campylobacter spp. contain plasmid, e.g. 53% of isolates from animals contained plasmid DNA ranged in size from less than 1 to 86 MDa • Resistance to tetracycline and gentamicin were probably plasmid mediated • Most strains were susceptible to kanamycin, clindamycin, chloramphenicol, kanamycin, tobramycin, streptomycin, erythromycin, gentamicin, tetracycline, and compound sulfonamide

36. Plasmid Profile and Antibiotic Resistance • In another study, tetracycline resistance was detected in six out of nine C. coli isolates (67 %) and 13 out of 74 C. jejuni isolates (18 %). • Both low- and high-level tetracycline resistance was associated with the presence of the tet(O) gene. • In C. jejuni, tet(O) was plasmid-encoded in 54 % of tetracycline-resistant isolates • whereas in C. coli, tet(O) appeared to be located on the chromosome

37. Plasmid Profile and Antibiotic Resistance

38. Plasmid Profile and Antibiotic Resistance • Partial sequence analysis of a tet(O) plasmid from a multiple-drug-resistant clinical isolate of C. jejuni revealed 10 genes or pseudogenes encoding different aminoglycoside inactivating enzymes, transposase-like genes, and multiple unknown genes from a variety of pathogenic and commensal bacteria

39. Plasmid Profile and Antibiotic Resistance • The plasmid in Lactococcus and Lactobacillus species contains two putative antibiotic resistance homologs, an ermB gene encoding erythromycin and clindamycin resistance, and a streptomycin resistance gene, aadE. • Of particular note is the aadE gene which holds 100% identity to an aadE gene found in C. jejuni plasmid but which probably originated from a Gram-positive source

40. Serotyping • Serological typing of the campylobacters is complex and several schemes have been devised, however, no uniform serotyping scheme has been adopted, and there are over 50 recognized serotypes of C. jejuni • Antigens used for serological typing include heat stable and heat labile antigenic factors, outer membrane proteins and flagellar antigens

41. Phage typing • A bacteriophage typing system was developed with phages isolated from poultry feces • Selection of 14 phages from the 47 phages available was assisted by determination of the Sneath-Jaccard similarity coefficients and subsequent unweighted pair-group arithmetic averaging cluster analysis • This typing set was reproducible and stable in the isolates from Illinois

42. Typing with lectins • Bacterial suspension, 50 ul, reacted with 50 ul of lectin solutions (lectins from different plants) in U-bottomed microtiter wells • Different reaction patterns were observed (Table 5). Heating of the cultures to 100C and holding for 30-60 min greatly enhanced their reactivity with lectins

43. Typing with lectins

44. Restriction fragments • On the basis of restrictive digest, six types were identified with AfaI, seven types with MboI and five types with HaeIII. • With a combination of these three enzymes, 22 types were found

45. Restriction fragments

46. PCR methods • PCR methods are also developed. Based on a 10-mer primer (5'-CCTGTTAGCC-3'), a random amplified polymorphic DNA (RAPD) method for typing C. coli isolated from pigs was developed

47. PCR methods • Amplified fragment length polymorphism (AFLP) patterns was applied to type C. jejuni isolates from human and chicken • AFLP原理

48. PCR methods • The published genome sequence of C. jejuni strain NCTC 11168 was used to model an accurate and highly reproducible fluorescent amplified fragment length polymorphism (FAFLP) analysis. • Predicted and experimentally observed amplified fragments (AFs) generated with the primer pair HindIII+A and HhaI+A were compared

49. PCR methods

50. PCR methods • A molecular typing approach for C. jejuni and C. coli was developed with restriction fragment length polymorphism analysis of a 9.6-kb PCR-amplified portion of the lipopolysaccharide gene cluster.