YERSINIA K R.pptx

1. YERSINIA
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2. INTRODUCTION
 Yersiniais a genus of bacteria which belongs to
family Enterobacteriaceae.
 This genus consist of small delicate gram negative
rods, coccobacilli bacteria, a few micrometre long
and are facultative anaerobes.
 They are primarilyparasites of animals in which they
cause generalized infections, some members of
yersiniaare pathogenic in humans.
 Yersiniacontains 3 medically important species that
are Yersiniapestis (plague),Yersinia
pseudotuberculosisand Yersiniaenterocolitica
(human diarrhoealdiseases)which are pathogenic
for animalsand human.
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3. Yersinia pestis
 Yersiniapestis is a gram negative, rod shaped, facultative anaerobic bacterium known for
causing the plague in humans and other mammals
 Yersiniapestis was first discoveredby a French born Swiss bacteriologistnamed
Alexander yersinin 1894.
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4. MORPHOLOGY
 Yersiniapestis shows bipolar staining, short, ovoid, rounded ends, safety pin
shaped bacillus or boat shaped in appearance.
 It measures 1.5 to 2 um long and 0.5 to 0.7 um in width, occurring singlyor in pairs.
The organismshows marked pleomorphism.
 It is gram negative and when stained with a weak stain, such as methylene blue,
shows characteristic bipolar staining, an important feature in its identification.In
fluid media it tends to grow in long chains
 In the animal tissues, a typical capsule may be observed.
 They are non-motile, non-acid fast and non sporingsurroundedby slime layer.
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6. CHARACTERISTICS
 IT IS NON-HEMOLYTIC
 GROWTH IS FASTER AT 25 TO 28 DEGREE
C.
 NON-MOTILE AT 35 TO 37 DEGREE C
CLUMPED GROWTH IN BROTH AT 25 TO
28 DEGREE C.
 IT IS CATALASE POSITIVE
 M R POSITIVE
 OXIDASE NEGATIVE
 UREASE NEGATIVE
 NITRATE REDUCTION NEGATIVE
 V P NEGATIVE
 INDOLE NEGATIVE
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7. Cultural characters
It is aerobic and facultativeanaerobic.
Optimumtemperaturefor growth is 27 degreeC.
OptimumpH for their growth is 7.2.
It can grow in 3 percent sodium chloride.
 Broth shows flocculent growthoccurring at the bottom and along side of the tube with
little or no turbidity
 Ghee broth shows growth which hangs down from the surface into the broth resembling
stalactites.
 Nutrient agar: colonies are smalland transparentbecoming opaque on continued
incubation.
 Blood agar : colonies are darkbrown due to absorptionof hemin pigment.
 Mac Conkey medium: colonies are colourless.
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8. EPIDEMIOLOGY
 Plague is an epizootic in rats and over 200 species of wild rodents
are now known to be susceptible to infection.
 The disease becomes really serious when the infection spreads to
species of black rat, known as Rattus. Rattus that flourish in and
around human habitation. The infection is spread by rat fleas,
zenopsylla cheopis. The duration for which rat flea remains infective
depends on temperature and humidity. A temperature above 10
degree Celsius is very favourable and dry temperature over 27
degree Celsius is unfavourable
 Some subcutaneous haemorrhages producing dark spots appear
which may account for this name of black death.
 Yersinia pestis may enter the body via the blood stream, the skin, the
conjunctive or mucous membrane of the respiratory tract
 Plague was present in the west in the pre-Christianera, but the
extent of the disease is unknown.
 The first documented pandemic occurred during the reign of
Emperor Justinian in 542 A.D. It probably began in the middle east
and spread widely after 60 years. Approximately 100 million persons
died of the infection and towns were completely decimated.
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10.  When the rat population is seriously reduced in numbers by the disease, the fleas turn to man as an
alternative host and produce an epidemic.
 The second pandemic known the “black death” which swept over Europe during the fourteenth century
killed about one quarter inhabitants. Smaller epidemics during the sixteenth, seventeenth and
eighteenth centuries, have claimed innumerable victims.
 In India during 1896 to 1910 more than 10 million people died of plague.
 Plague is endemic in certain parts of India, Bangladesh, Burma, Java, China, South Africa, Central and
East Africa. It occurred in sporadic form in Egypt, Iraq, Iran, Thailand and Indo-china.
 The disease occurred during summer months in cool climates and in spring months in the hot dry
climates of the subtropics and tropical countries. It fallowed humidity curve.
 Persons of all ages, races and both sexes were effected by bubonic plague.
 Doctors, nurses and other paramedical staff who care for patients with pneumonic plague and other
contacts, including funeral attendants, were effected from pneumonic plague.
 Strains of Yersinia pestis reconverted from man, rats, wild rodents and fleas from every corner of the
world are biologically identical and remarkably homogeneous in virulence and infectious ness.
 Disease may also be carried by partial migration of rodents in food grains. Rats surviving the epizootic
acquire resistance to infection and this may limit the spread of the disease.
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11. TYPES OF PLAGUES
 There are three clinical types of plague namely :-
A. BUBONIC PLAGUE :- Bubonic plague is most common.
Following the bite of an infected flea there is enlargement of
the regional lymph node, most frequently the inguinal, to form
the characteristic buboes. The blood is invaded and
widespread infection results. This form of the disease is not
readily transmitted from man to man.
B. PNEUMONIC PLAGUE :- In this case the organisms set up a
focus of infection in the lungs the result is a rapidly spreading
haemorrhagic bronchopneumonia. The sputum with Yersinia
pestis and the patient is highly infectious. Case-to-Case
transmission of pneumonic plague occurs by droplet infection
and rat fleas are not involved.
C. SEPTICAEMIC PLAGUE :- In this case there is early invasion of
the blood. It is characterized by the sudden onset of high fever
without associated bubo. Illness leades to overwhelming
sepsis and organ failure within a few days. There is no
Involvement of lymph nodes and lungs.
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12. PATHOGENICITY
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13. The flea, xenopsylla cheopis or others became infected by sucking blood from a
plague infected rat, which may contain very large number of bacilli.
These organisms multiply in the midgut of the flea and massive infection develops
in the proventriculus, blocking the pharynx and the oesophagus. When such
infected flea attempts to take its next blood meal, large number of plague bacilli are
regurgitated into the skin or capillaries of the new mammalian host. The bacilli are
also discharged in faeces and infection may occur by contamination of the bite
wound by faeces. Rats may be infected by feeding upon disease dead rats. Other
rodents may replace the rat.
Human flea, pulex irritants appears to be incapable of transmitting the disease
from rat to man but under certain circumstances, epidemic bubonic plague in man
in transmitted largely from man to man by human flea, pulex irritans.
 In cases of SEPTICAEMIC PLAGUE, the bacilli present in blood stream and may
prove fatal in 25 to 50% of cases in the absence of treatment.
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14. BUBONIC PLAGUE is much more common than the pneumonic plague. The essential for the
development of bubonic plague in man is the primary rat-flea-rat transmission cycle.
Temperature is in the range of 10 to 30 degree C. There is an incubation period of 2 to 8 days.
The organisms may then be present in relatively small numbers in the blood stream but are
present in large number in the inguinal lymph nodes, if the leg is the site of inoculation. The
glands are markedly swollen along with the periglandular tissue and produce a localised
mass, referred to as the primary bubo which is filled with plague bacilli during the initial
stages. Secondary bubos may develop in other lymph nodes. Rarely bubos may be axillary
or cervical regions depending on the site of bite. The bubo is painful. Haemorrhage and
necrosis may develop in the bubo
In some patients contracting bubonic plague from a rat or rodent, the bacteria may lead to
severe bronchopneumonia and produce PNEUMONIC PLAGUE, in which the plague bacilli
become localised in the lungs and produce sudden haemorrhagic bronchopneumonia. The
bacilli are present in large number in sputum which is highly infectious in this form of the
disease and thus primary pneumonic plague may spread from man to man through
respiratory route and true epidemic may occur. Cyanosis, of course is extreme in the later
stages of the disease and probably accounts for the name “Black death” applied to
pneumonic plague.
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15. MODE OF TRANSMISSION
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16. The Yersiniapestisplague can be transmitted to humans in the following ways:
 FLEA BITES :- plague bacteria are most often transmitted by the bite of an infected flea. During
plague epizootics, many rodents die, causing hungry fleas to seek other sources of blood.
People and animals that visit places where rodents have recently died from plague are at risk
of being infected from flea bites. Dogs and cats may also bring plague-infected fleas into the
home. Flea bite exposure may result in primary bubonic plague or septicemic plague.
 CONTACT WITH CONTAMINATED FLUID OR TISSUE :- Human can become infected when
handling tissue or body fluid of a plague infected animal or human. This form of exposure most
commonly results in bubonic plague or septicemic plague.
 INFECTIOUS DROPLETS :- When a person has plague pneumonia,they cough droplets
containing the plague bacteria into air. If these bacteria containing droplets are breathed in by
another person they can cause pneumonic plague. Typically this requires direct and close
contact with the person with pneumonic plague. Transmissionof these droplets is the only
way that plague can spread between people.
 Cats gets infected by eating infected rodents. Sick cats pose a risk of transmitting infectious
plague droplets to their owners or to veterinarians.
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17. SYMPTOMS
 Plague symptoms depend on how the patient was exposed to the plague
bacteria.
 Plague can take different clinical forms, but the most common are
Bubonic plague, Pneumonic plague, Septicemic plague - Depending on
which part of the body is involved.
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18. Bubonic plague
The incubation period of bubonic plague is usually 2 to 8 days.
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19. Patients develop
• fever and chills
• Weakness
• Headache
• Fatigue
• Muscle aches
• One or more swollen, painful lymph nodes (called buboes)
Buboes may be
• situated in the groin, armpit or neck
• About the size of a chicken egg
• Tender and firm to the touch
This form usually results from the bite of an infected flea. The bacteria multiply
in a lymph node near where the bacteria entered the human body. If the patient
is not treated with the appropriate antibiotics, the bacteria can spread to other
parts of the body.
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20. Pneumonic plague
 The incubation period of pneumonic plague is usually 1 to 3 days.
 Pneumonic plague may develop from inhaling infectious droplets or septicemic plague
after the bacteria spread to the lungs. The pneumonic may cause respiratory failure and
shock.
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21.  Pneumonic plague is the most serious form of the disease and is the only form of
plague that can be spread from person to person by infectious droplets.
 Patients develop
• Fever
• Headache
• Weakness
• Rapidly developing pneumonia with
shortness of breath
• Chest pain
• Cough with bloody mucous (sputum)
• Nausea and vomiting
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22. Septicemic plague
 The incubation period of septicemic plague is poorly defined but
likely occurs within days of exposure.
 Skin and other tissues may turn black and die, especially on
fingers, toes, and the nose.
 septicemic plague can occur as the first symptom of plague or may
develop from untreated bubonic plague.
 This form results from bites of infected fleas or from handling an
infected animal.
 Patients develop
• Fever and chills
• Extreme Weakness
• Abdominal pain
• Diarrhea and vomiting
• Shock
• Bleedingfrom mouth, nose or rectum or under skin
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23. Laboratory
DIAGNOSIS
Plague should be suspected in febrile
patients who have been exposed to
rodents in known endemic areas.
Rapid recognition and lab confirmation
of disease are essential in order to
institute lifesaving therapy.
The samples used for diagnosis of
plague are:-
1)Pus or fluid from bubo in bubonic
plaque.
2)Sputum from a case of pneumonic
plague.
3)Blood sample from early phase or
septicaemic.
4)Splenic tissue at post mortem.
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24. COLLETION OF MATERIAL
Diagnosisis liable to be missed in sporadic cases and infection withYersiniapestis,the
early diagnosis is of vital importance to the patient, attendant staff and the whole
community.
The bubo is punctured with a hypodermic needle and an exudate is collected and in the case
of pneumonic plague sputum sample is collected and subjected to the following
examinations.
1) Microscopic examination
2) Culture
3) Biochemicalreactions
4) Animal inoculation
5) Precipitation test
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25. 1) MICROSCOPIC EXAMINATION :- The
films are dried and stained with methylene blue and another with grams method.
The presence of typical characteristic bipolar stained bacilli is highly suggestive.
Fluorescent microscopy is more rewarding in the early diagnosis of the disease.
2) CULTURE :-
The exudate or morbid material is cultured on blood agar, the plates being incubated
at 30 degree C for 24 to 48 hours and a single typical colony is sub-cultured on 3%
salt agar, and chain formation in broth and stalactite growth on oil broth is noted.
3) BIOCHEMICAL REACTIONS :-
The following tests are positive, fermentation of glucose, mannitol, maltose with the
production of acid only, catalase test and methyl red reaction. Lactose, sucrose,
dulcitol, indole production, oxidase test, V.P. reaction and gelatine liquefaction are
negative.
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26. 4) ANIMAL INOCULATIONM :- Some of the exudate is injected subcutaneously
into a guinea pig or white rat. In case the exudate will die, showing at autopsy
the characteristic local and general lesions from which the organisms can be
demonstrated and isolated.
• In the case of pneumonic plague the animal is inoculated with sputum.
• Instead of injecting subcutaneously, the material may be applied to the
freshly shaved area of skin
• A nasal mucosa or conjunctiva Yersinia pestis can frequently be isolated
from the blood during the early stage of the disease.
5) PRECEPITATION TEST :- It may be used to examine decayed or mummified
carcasses during field investigation of suspected plague outbreak among wild
rodents.
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27. TREATMENT/prophylaxis
 The treatment of choice for humans with plague is streptomycin.
 Gentamicin has been used to treat both human and animal.
 Doxycycline is an appropriate choice for less complicated cases. Other treatment
options include Chloramphenicol and tetracyclines. Sulphadiazine can be used but
only if other antimicrobials are not available.
 Antibiotics preferably should be administered intravenously, unless a mass
outbreak situation results, in such case orally administered tetracycline,
doxycycline or ciprofloxacin is considered an acceptable alternative.
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28. The most important methods in treatment are:
 GENERAL MEASURES
Reduction in the rat populationby the use of dicoumarin,sodium fluoro-acetate and alpha-
naphthyl thiourea chemical rodenticides,plays an important role in plague control .
 SPECIFIC MEASURES
Two types of vaccine have been used for specific prophylaxis.
a) KILLED VACCINE
It is a bacterial culture antigen.A virulent strain of plague bacillus is grown in casein
hydrolysatebroth for 2 to 4 weeks at 32 degree C and killed by 0.05% formaldehydeand
preserved with phenyl mercuric nitrate. Standardizationis carried out by immunogenic
potency rather than by bacterial count.
b) LIVE ATTENUATED VACCINE
The two avirulentstrains were used for preparationof live vaccine.
Since live vaccines are difficult to prepare and distribute for mass immunization,so killed vaccine
is recommendedfor general use. The live vaccine may provoke reactions.
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29. PREVENTION
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30.  Reduce rodent habitat around your home, work place and recreational areas. Remove brush, rock piles,
junk, cluttered firwood and possible rodent food supplies, such as pet and wild animal food. Make your
home and outbuildings rodent proof.
 Wear gloves if you are handling or skinning potentially infected animals to prevent contact between your
skin and the plague bacteria.
 Contact your local health department if you have questions about disposal of dead animals.
 Use repellent if you think you could be exposed to rodent fleas during activities such as camping, hiking
or working outdoors. Products containing DEET can be applied to the skin as well as clothing and product
containing permethrin can be applied to clothing
 Keep fleas off of your pets by applying flea control products. If your pets becomes sick, seek care from a
veterinarian as soon as possible.
 Do not allow dogs or cats that ram free in endemic areas to sleep on your bed.
 Public health education.
 Vaccination may reduce the morbidity.
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31. REFERENCES
BOOKS
 Medical Microbiology (4th edition) – by C.G.A Thomas
 Textbook of Medical Microbiology – by H L Chopra
 The Short Textbook of Medical Microbiology (8th edition) – by Satish Gupte
 Introduction to Medical Microbiology – by R. Ananthanarayan
 The Short Text Book of Medical Microbiology (3rd edition) – by Satish Gupte
 Bailey and Scott’s Diagnostic Microbiology (7th edition) – by Sydey M. Finegold and Ellen Jo
Baron
WEBSITES
 www.cdc.gov
 www.ncdi.nlm.nih.gov
 www.mayoclinic.org
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