YERSINIA .pptx

YERSINIA K R.pptx

1. YERSINIA K R MICRO NOTES 1

2. INTRODUCTION Yersinia is 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 primarily parasites of animals in which they cause generalized infections, some members of yersinia are pathogenic in humans. Yersinia contains 3 medically important species that are Yersinia pestis (plague), Yersinia pseudotuberculosis and Yersinia enterocolitica (human diarrhoeal diseases) which are pathogenic for animals and human. K R MICRO NOTES 2

3. Yersinia pestis Yersinia pestis is a gram negative, rod shaped, facultative anaerobic bacterium known for causing the plague in humans and other mammals Yersinia pestis was first discovered by a French born Swiss bacteriologist named Alexander yersin in 1894. K R MICRO NOTES 3

4. MORPHOLOGY Yersinia pestis 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 singly or in pairs. The organism shows 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 sporing surrounded by slime layer. K R MICRO NOTES 4

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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 K R MICRO NOTES 6

7. Cultural characters It is aerobic and facultative anaerobic. Optimum temperature for growth is 27 degree C. Optimum pH for their growth is 7.2. It can grow in 3 percent sodium chloride. Broth shows flocculent growth occurring 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 small and transparent becoming opaque on continued incubation. Blood agar : colonies are dark brown due to absorption of hemin pigment. Mac Conkey medium : colonies are colourless. K R MICRO NOTES 7

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-Christian era, 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. K R MICRO NOTES 8

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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. K R MICRO NOTES 10

11. TYPES OF PLAGUES There are three clinical types of plague namely :- 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. 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. 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. K R MICRO NOTES 11

12. PATHOGENICITY K R MICRO NOTES 12

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. K R MICRO NOTES 13

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. K R MICRO NOTES 14

15. MODE OF TRANSMISSION K R MICRO NOTES 15

16. The Yersinia pestis plague 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. Transmission of 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. K R MICRO NOTES 16

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. K R MICRO NOTES 17

18. Bubonic plague The incubation period of bubonic plague is usually 2 to 8 days. K R MICRO NOTES 18

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. K R MICRO NOTES 19

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. K R MICRO NOTES 20

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 K R MICRO NOTES 21

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 Bleeding from mouth, nose or rectum or under skin K R MICRO NOTES 22

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:- Pus or fluid from bubo in bubonic plaque. Sputum from a case of pneumonic plague. Blood sample from early phase or septicaemic. Splenic tissue at post mortem. K R MICRO NOTES 23

24. COLLETION OF MATERIAL Diagnosis is liable to be missed in sporadic cases and infection with Yersinia pestis , 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. Microscopic examination Culture Biochemical reactions Animal inoculation Precipitation test K R MICRO NOTES 24

25. 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. 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. 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. K R MICRO NOTES 25

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. K R MICRO NOTES 26

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. K R MICRO NOTES 27

28. The most important methods in treatment are: GENERAL MEASURES Reduction in the rat population by 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 hydrolysate broth for 2 to 4 weeks at 32 degree C and killed by 0.05% formaldehyde and preserved with phenyl mercuric nitrate. Standardization is carried out by immunogenic potency rather than by bacterial count. b) LIVE ATTENUATED VACCINE The two avirulent strains were used for preparation of live vaccine. Since live vaccines are difficult to prepare and distribute for mass immunization, so killed vaccine is recommended for general use. The live vaccine may provoke reactions. K R MICRO NOTES 28

29. PREVENTION K R MICRO NOTES 29

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. K R MICRO NOTES 30

31. REFERENCES BOOKS Medical Microbiology (4 th edition) – by C.G.A Thomas Textbook of Medical Microbiology – by H L Chopra The Short Textbook of Medical Microbiology (8 th edition) – by Satish Gupte Introduction to Medical Microbiology – by R. Ananthanarayan The Short Text Book of Medical Microbiology (3 rd edition) – by Satish Gupte Bailey and Scott’s Diagnostic Microbiology (7 th edition) – by Sydey M. Finegold and Ellen Jo Baron WEBSITES www.cdc.gov www.ncdi.nlm.nih.gov www.mayoclinic.org K R MICRO NOTES 31

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