Legionella Listeria Campylobacter Helicobacter MBBS Undergraduates Lecture

1. Miscellaneous bacteria
(Legionella, Listeria,
Campylobacter, Helicobacter)
Dr. Abhijeet Mane
Assistant Professor
Department of Microbiology
BVDUMC, Pune

2. Campylobacter
 Introduction
 Campylobacter spp. Cause both diarrheal and
systemic diseases
Motile, non sporing, microaerophilic, curved GNB
 Human pathogens: 2 major groups
 Primary diarrheal diseases: C.jejuni and others
 Extraintestinal disease: C.fetus

3. • Epidemiology
• Source: zoonotic
• Mode of transmission:
▫ Raw / undercooked food – poultry, milk
▫ Direct contact with infected household pets
▫ Travel to developing countries
▫ Oral – anal sexual contact
• Age
▫ C.jejuni – common among children
▫ C.fetus – extremes of ages

5. • Most common cause of bacterial diarrhea in
developed countries
• Peaks in summer and early autumn

6. • Pathogenesis
▫ Expression of following virulence factors:
 Motility of strain – polar, single flagellum
 Capacity to adhere to host tissues
 Enterotoxin (minor role)
 Cytotoxin (minor role)

7. • Clinical manifestations
• Intestinal infection
▫ Inflammatory diarrhea, abdominal pain, fever
▫ Loose stools to bloody diarrhea, self limiting
• Extraintestinal
▫ Due to C.fetus
▫ Bacteremia, sepsis, meningitis, vascular infections
• In HLA-B27 phenotypes
▫ Reactive arthritis
• Campylobacter triggers GBS and alpha chain disease

8. Laboratory diagnosis
• Direct microscopy
▫ Gm stain – curved, GNB, 0.2-05 x 1.5-5um
▫ Appear comma shaped, S-shaped or spiral (gull
wing-shaped)
▫ Dark ground microscopy – darting motility of
bacilli

10. • Culture
• Transport medium: Cary – Blair medium
• Selective medium
▫ Feces or rectal swabs plated on to
▫ Skirrow’s selective medium
▫ Butzler’s selective medium
▫ Campy BAP (lysed blood agar,)
• Microaerophilic
• Growth at 42degC : seen (not by C.fetus)
• Colonies are effuse, droplet like.

12. • Biochemicals
▫ Oxidase positive, catalase positive, nitrate
reduction, do not ferment sugars
• Treatment
▫ Fluid and electrolyte replacement
▫ Diarrheal disease: oral macrolides
▫ Systemic infection: parenteral Gentamicin

13. Helicobacter
• Curved GNB, colonizes stomach
• Associated with peptic ulcer disease and gastric
carcinoma

14. Pathogenesis
• Motility
▫ Highly motile (4 – 8 unipolar flagella)
• Acid resistance
• Urease enzyme
▫ Amidase and Arginase
▫ Ure – I protein – regulates passage of urea across
the cell membrane into cytoplasm
• Adhesins
• Resistance to oxidative stress

15. • Pathological changes induced
▫ Vacuolating cytotoxin (VacA) – induces formation
of vacuoles in cytoplasm
▫ Cytotoxin associated Gene A (Cag A):
▫ Alteration in gastric mucus
▫ Smoking, diets high in salt and preserved foods

16. Clinical manifestations
• Acute gastritis – antrum MC site involved
• Peptic ulcer disease
• 80% duodenal ulcers and 60% gastric ulcers due
to H.pylori
• Chronic atrophic gastritis
• Autoimmune gastritis
• Pernicious anemia
• Adeno Ca stomach
• Non Hodgkin’s gastric lymphoma

17. Laboratory diagnosis
• Invasive test
• Endoscopy guided multiple biopsies can be taken
from gastric mucosa
• Histopathology - Warthin Starry silver staining
• Microbiology
▫ Gram stain: curved, GNB, sea gull shaped morphology
▫ Culture media
 Skirrow’s, CA,
 37deg c under microaerophilic condition
 Biochemicals – oxidase, catalase, urease positive
 Biopsy urease test (Rapid urease test)

20. • Non invasive test
• Urea breath test: drink urea
labeled with nonradioactive
13C, CO2 detected in breath
• Stool antigen assay
• Antibody (IgG) detection by
ELISA

21. Treatment
• Indicated for duodenal and gastric ulcer and low
grade gastric B cell lymphoma
• Omeprazole + clarithromycin+metronidazole for
7-14 days
• omeprazole+bismuth+metronidazole+tetracycli
ne for 14 days

22. Legionella
• Fastidious, pleomorphic, GN short rods
▫ Pontiac fever – acute, milder flu like self limited
▫ Legionnaires’ disease – severe interstitial
pneumonia
• History
▫ 1st recognised in 1976; outbreak of pneumonia
took place in Philadelphia hotel during America
Legion convention

25. • Classification
• L.pneumophila – most important species, 80-
90% human infections. Majority serogroup 1
• L.micdadei, Lbozemanii, etc

26. Epidemiology
• Reservoir: inhabits water bodies
▫ Natural water sources, rivers, streams
▫ Artificial aquatic sources – Acs, water coolers
• No animal reservoir
• No carrier stage
• Transmission
▫ Aspiration – oropharyngeal colonisation or
drinking contaminated water
▫ Aerosols
▫ No man-to-man transmission

28. • Predisposing factors
▫ Smoking, alcoholism, chronic lung disease
▫ Advanced age
▫ Immunosuppressant
▫ Prior hospitalization

29. Pathogenesis
• Attachment to respiratory mucosa by bacterial
type IV pili, heat shock proteins, a major OMP
and complement
• Both macrophages and neutrophils recruite to
local sites
• Evades intracellular killing by inhibiting
phagosome-lysosome fusion

30. Clinical manifestations
• Pontiac fever
• Legionnaires’ disease (Pneumonia)
▫ Interstitial atypical pneumonia, IP – 2-10 days
▫ Non productive cough, dyspnea, chest pain, high fever,
diarrhea
▫ Confusion, altered mental status
• Chest x-ray- pulmonary infiltrates
• Extrapulmonary Legionellosis
▫ Blood borne dissemination from lung
▫ Myocarditis, pericarditis, endocarditis
▫ Sinusitis, peritonitis, pyelonephritis, etc

32. Laboratory diagnosis
• Specimen: sputum, BAL, bronchial wash, PF
• Direct Microscopy
▫ Gram stain: many neutrophils but no organisms
▫ Silver stains or Giemsa stains can be used
▫ Direct IF

33. • Culture
▫ Highly sensitive and specific
▫ Buffered charcoal, yeast extract (BYCE) agar:
▫ 37degC x 3-5 days, round, glistening, convex,
green or pink iridescent colonies
• Biochemicals – catalase positive, oxidase
negative, motile, hippurate hydrolysis positive
(only L.pneumophila)
• Other: Antibody detection, urinary Ag detection,
PCR

35. Treatment
• Macrolides (azithromycin) and respiratory
Quinolones – DOC

36. Listeria
• Listeria monocytogenes
▫ Food borne pathogen, serious infection in neonates,
pregnant women, elderly people
▫ Ubiquitous saprophyte
• Human infection
▫ Transmitted thru contaminated food, mother-to-fetus
▫ Common among extremes of ages
▫ Commonly found in stored foods, soft cheese,
packaged meat, milk, cold salad
▫ Most often sporadic

38. Pathogenesis
• Entry: in intestinal EC mediated by host surface
proteins internalins
• Intracellular survival: facultative intracellular
organism, inhibits phago-lysosome formation
• Direct cell-to-cell spread

39. Clinical manifestations
• Serotype - 1/2a, 1/2b, 4
• Neonatal listeriosis
• Pregnant women
• Fetal – abortion, preterm delivery
• Maternal – flulike symptoms, bacteremia, rarely
meningitis
• Adults
▫ Bacteremia and meningitis
▫ Common risk factor immunosuppression
▫ Gastroenteritis following consumption of
contaminated milk, meat, salads

40. Laboratory diagnosis
• Specimens – CSF, blood, amniotic fluid, etc
• Gram stain – Gram positive short coccobacilli
• Motility – tumbling type at 25degC, non motile
at 37degC
• Culture – grows on BA(BH colonies), CA and
selective media such as PALCAM agar
• Growth improves on refrigeration at 4degC in
trypticase soy broth followed by s/c

42. • Biochemical reaction
▫ Catalase positive
▫ Can grow in 10% salt and low pH
▫ CAMP positive
▫ Ferments glucose, maltose, L-rhamnose
• Treatment
▫ Ampicillin – DOC
▫ Cotrimoxazole

43. Thank you!!