This document summarizes several bacterial genera - Yersinia, Pasteurella, and Francisella. It describes their general properties, species, diseases caused, morphology, culture characteristics, biochemical reactions, epidemiology, pathogenesis, laboratory diagnosis, treatment and prophylaxis. Key points include Yersinia pestis causing plague, Pasteurella multocida causing septicemia, and Francisella tularensis causing tularemia.

1. Yersinia, Pasteurella, Francisella
Dr. Kanwal Deep Singh Lyall
M.D. Microbiology

2. General properties
• GNB, showing bipolar staining with M. blue
• NM – except Y. pseudotuberculosis & Y.
enterocolitica
• 1° rodent pathogens, accidental infection in
humans
Genera Species Diseases
Yersinia Y. pestis
Y. pseudotuberculosis
Y. enterocolitica
Plague
Pseudotuberculosis
Eneteritis
Pasteurella P. multocida H’gic septicemia
Francisella F. tularensis Tuleraemia

3. Y. pestis
• Family Enterobacteriaceae, tribe Yersiniae
• Causes – Plague – Pasteurella pestis
• Isolated independently by Yersin & Kitasato
(1894)

4. Ring A Ring O’ Roses,
A Pocketful Of Posies,
Atishoo Atishoo,
All Fall Down !!!
Ring Around The Rosie
Pocket Full Of Posies
Ashes Ahes
All Fall Down !!!

5. Morphology
• Short, ovoid, GNB, single, sh. Chains or gps
• With M. blue bipolar staining – safety pin
appearance
• Pleomorphic – enhanced by 3% NaCl - cocci,
clubs, filaments etc.
• Has a slime layer (capsule)
• NM, non-sporing & Non-AFB

6. Culture
• Aerobic, Fac. anaerboic, optimum t° 27° C, but
envelope develops @ 37° C
• NA- small, delicate, transparent
• BA – N-H’lytic, brown d/t absorption of haemin
pigment
• MA – NLF
• Broth – growth at sides & at bottom of tube
• Ghee broth – flask with broth with ghee floating –
stalactite growth

7. Biochemical reactions
• NLF, does not ferment Sucrose, ferments G,M
& M without gas
• Catalase +ve, oxidase – ve , indole – ve, urease
–ve , MR + ve , VP –ve
Devignat’s biotypes
Glycerol fermentation Nitrate reduction
Y. P var. orientalis - +
Y. P var. antiqua + +
Y. P var. mediavalis + -

8. Resistance
• Die in heat @ 55 C x 15 minutes
• Survive for months in soil of rodent burrows

9. Antigenic structure
• No serotypes but ≈ 20 different Ags

10. Antigenic structure
Fraction I OR F-I: heat
labile protein envelope Ag,
inhibits phagocytosis,
present in virulent strains
& induces protective
immunity
Bacteriocin (Pesticin I) ,
fibrinolysin, Coagulase
V & W proteins:
Virulent, phagocytosis
Endotoxin (LPS) similar to
entric bacteria, k/a plague
toxin
The ability to absorb haemin &
produce purines have been
associated with virulence

11. Epidemiology
• Zoonotic infection – rats – may become
epidemic – flea – one rat to another
• Rat flea – Xenopsiella cheopis, X. astia,
Ceratphylus
• Black death – extreme deprssion
• Killed millions in past
• 1994 outbreak in Surat (Gujrat) & Beed
(Maharashtra) – bubonic & pneumonic

12. RAT
Pathogenesis
DEATH
RAT FLEA

13. Plague
Bubonic – flea bite – LN involved –
enlarge & suppurate – bubo (meaning
groin as m/c inguinal LNs) – pain, fever,
chills, malaise – if untreated –
dissemination – meningeal involvment
Pneumonic – H’gic – highly
infectious – droplet
infection or via blood –
fever, cough, expectoration
Septicemic – usually terminal event of above – massive
invovement of blood vessels – bleeding – black death

14. Lab diagnosis
• BLS level 3
• Diagnosis in humans
• Diagnosis in rodents – to prevent spread
• Samples :
– pus, fluid from bubo in bubonic
– Sputum, blood in pneumonic
– Splenic tissue post-mortem
– CSF in meningeal

15. Sample
G/S , Methylene
blue & buffy coat
in septicemic
GNCB with
bipolar staining
CultureDirect
microscopy
BA X 27 ̊ C
Or Ghee broth
Animal
inoculation
s/c inj of Borth,
exudate etc.
Local inflammation,
necrosis, edema,
regional LAP – Death
Demonstration by G/S, MB or S/C
Serology
Limited value Abs to F1
Ag By CFT, passive
agglutination etc.
Positive after 1st week
to many years
Biochemical Rx

16. Diagnosis in rats
• Immerse in disinfectant to kill fleas
• Enlarged cervical LNS as flea bites on neck
• Pleural effusion, splenomegaly, H’ges in skin &
internal organs
• Specimens – heart blood, spleen, LNs

17. Treatment & prophylaxis
• TET (DOC), STM, CPC, Kanamycin
• Flea & rodent control
• Kill fleas 1st
• Insecticides in rodent burrows & houses
• f/b rodenticides

18. Vaccine
• Killed whole bacterial culture Ag – Haffkine
Institute, Mumbai – Sokhey’s modification –
0.05 ml s/c f/b 1ml 7-14 days latter – 6m-
Immunity 6m – not very effective
• Live vaccine – two avirulent strains of Y. pestis
– Otten’s Tjiwidej strain from Jawa & Girard’s
EV 76 strain from Malagasey – difficult to
prepare & impracticle

19. Y. Pseudo-tuberculosis & Y. enterocolitica
• Resemble Y. pestis – small GNB with bipolar
staining
• Reservoirs in rodents, wild & domestic animals
• Differ from Y. pestis by their motility @ 22 °C
& not @ 37°C
• Yersiniosis = infection other than Y. pestis

20. Y. Pseudo-tuberculosis
• 6 serological gps & 9 serotypes – based on
somatic & flagellar Ags
• Zonotic infection – GPs, rabbit, birds etc.
• Multiple nodules resembling Tb in liver, spleen
& lungs of infected animals – hence pseudo-Tb
• Human infection – ingestion of food
contaminated with animal faeces – leading to
mesenteric lymphadenitis or sever gen. Ds

21. Lab diagnosis
• Isolation from mensenteric LNs
• Serology – AB detection
• Non-sucrose fermenting

22. Y. enterocolitica
• Also motile @ 22° C but sucrose fermenting &
decarboxilating ornithinie, NLF, Non-H’tic
• Some strains Indole & VP + ve
• 60 O-Agic gps & 20 heat-labile H-Ags
• Most human infections – O3, O8 , O9
• Zonotic infection – faeco-oral route
• GE, mesenteric LAP, septocaemia
• Diarrhoea d/t enterotoxin or mucosal invasion
• Dx – culture & Ab detection

23. Pasteurella multocida (P. septica)
• Pasteur developed 1st attenuated vaccine from
P. aviseptica – hence Pasteurella
• P. boviseptica, P. letiseptica, P.aviseptica = all
k/a P. multocida
• GNB, oxidase +ve, does not grow on MA
• Dogs, rats. Cats – bite – septic wound or
meningitis following head injury
• Haemorrhagic septicaemia

24. Francisella tularensis
• NM. GNB, capsulated
• Zoonotic Ds – rabbits & other rodents
• Tulare County, California
• Human infection – handling or eating infected
meat, contaminated water or tick bites
• Francis blood dextrose cysteine agar – minute
transparent colonies x 3 – 5 days

25. • Highly infectious, lab infection is common
• Local ulceration, LAP, PUO, bacteremia, pulm.
Infections
• Lab Dx
– Pus, blood, sputum
– Smear, culture, GP inoculation
– Serology for agglutinating Abs - >1:80 +ve
– Cross Rx with Brucellosis
• STM is DOC, attenuated vaccine

26. X