This document discusses three genera of medically important bacteria - Vibrio, Aeromonas, and Plesiomonas. It focuses on Vibrio cholerae, providing details on its morphology, virulence factors, pathogenesis, clinical symptoms of cholera, laboratory diagnosis, treatment and prevention. It also briefly discusses Vibrio parahaemolyticus and Aeromonas species, noting their associations with seafood and ability to cause gastroenteritis, skin infections, and sepsis.

1. Sharq Elneil College
School of Medical Laboratory Sciences
Department of Microbiology
Medical Bacteriology course
Vibrios
U.Mahadi Hassan Mahmoud
Bsc, Msc, MIBMS Microbiology

2. 3 Important Genera:
 Vibrio
 Aeromonas,
 Plesiomonas
Oxidase +ve

4. Medically important species
Vibrio cholerae
Vibrio paraheamolyticus
Vibrio vulnificus

5. Clinical Syndromesspecies
Vibrio
–Vibrio cholerae 01 (This is a
specific powerful serotype)
• Mild diarrhea to severe deadly
diarrhea
–Depends on how much toxin produced
• Vomiting can also occur
• Lose 10-25 liters a day, sometimes 1
liter/hour

6. • Lose 50% of body weight during
course of disease
• Death within hours (renal
failure and shock)
• Self-limiting, but have to replace
fluids and electrolytes or high
likelihood of eventual death
Vibrio cholerae non01 (less
potent serotype)
• Much milder diarrhea, not life-
threatening

7. Vibrio species
Clinical Syndromes
Vibrio parahaemolyticus
•Seafood-associated
•Seen mostly in coastal regions
•Mild to moderate diarrhea
•Self-limiting disease, patients
recover uneventful

8. Vibrio vulnificus
Diarrhea associated with raw
oysters
A more threatening infection is
when patients get a wound
infection contaminated with
seawater
The wound infection progresses
rapidly and can cause death within
a day.

9. Morphology
 Gram negative curved rod, measuring
3–4 0.5 μm
 Have a single flagellum at one end.
In smears made from solid cultures, the vibrios
may appear less The use of dilute carbon fuchsin
(1 in 10) is recommended as a counterstain in the
Gram technique
when staining Vibrio species.
 V. cholerae 0139, unlike V. cholerae 01, is
capsulated surrounded by a thick
capsule.

10. I. V. cholera O1:
– Agglutinate in Antisera Directed
Against O1 Antigen.
– Produce Enterotoxin.
2. Non-Toxigenic V. cholera O1:
3. Non O1 V. cholera (NCV, NAV):
II. V. cholerae O139

11. Vibrio cholerae
Gram-negative, curved rods

12. Vibrio cholerae
Leifson flagella stain

13. Vibrio cholerae
curved rods with polar flagellum (EM)

14. V. cholerae O1
---------------------------------------------------
Biotye
El-tor Classic
Haemolysis (SRBC) + --
VP + --
Resistance to PB + --
---------------------------------------------------

15. VIRULENCE FACTORS:
o Enterotoxin: CT
o Adherence: Ability to Attach to
the Microvilli at the Brush
Borders of the Epithelial Cells.
EPIDEMIOLOGY:
o Causes Widespread Disease.
o Human Carriers:
o Modern International

17. PATHOGENESIS & CLINICAL
INFECTION:
 Infectious Dose:
Incubation period:
Abrupt Onset of Diarrhoea &
Vomiting
Stool > Watery (Rice Water),
Odorless
Fatality Rate:

18. LAB. DIAGNOSIS:
Isolation & Identification of the
Organism.
Media: TCBS
Transport Media:

19. TREATMENT:
Prompt Replacement of Fluid &
Elecrolytes
Tetracycline and others

20. PREVENTION & CONTROL:
Adequate Sewage Treatment and
Water Purification Systems.
Vaccination:

21. Typical Vibrio cholera
contaminated water supply

23. Vibrio parahaemolyticus
oHalophilic vibrio
o Associated with seafood
o Gastroenteritis:
oOutbreaks of Food Poisoning
o Extraintestinal infections > wounds
oVirulence Factors:
oHaemolysin >
oheat-stable cytotoxin
oHeat-labile enterotoxin
oAdherence to human intestinal
cells

24. Aeromonas species
A. hydrophila, A. sobria & A.
caviae
Enterotoxins, Cytotoxins,
Haemolysins, Etc…
Gastroenteritis, Septicaemia, and
Skin & Wound Infections
Antimicrobial Suscebtibility
testing:
TMP-SMX, Tetracycline, Gentamicin
Resistant to b-Lactam Antibiotics.