Lec 2. Yersinia Pestis and Plague PDF

Microbiology 2: Yersinia pestis and Plague Prof. Hazem Aqel Blood and Lymphatic System Basic Medical Sciences Objectives Describe the general microbiological properties and differences from other yersinia. Understand cultural techniques, epidemiology and pathophysiology. Describe the clin...

Microbiology 2: Yersinia pestis and Plague Prof. Hazem Aqel Blood and Lymphatic System Basic Medical Sciences Objectives Describe the general microbiological properties and differences from other yersinia. Understand cultural techniques, epidemiology and pathophysiology. Describe the clinical presentation, specimen collection for culture, treatment and prevention.  Morphology and the Structure ⑪ ② ③ Yersinia pestis is a non-motile, non–spore-forming, gram-negative bacillus with a tendency toward pleomorphism and bipolar staining. It is a member of the Enterobacteriaceae family and shares features of the other Yersinia pathogenic for humans (Y. pseudotuberculosis, Y. enterocolitica), such as virulence plasmids and multiple Yersinia outer membrane proteins (Yops). => => (toxic] Ye In addition, Y. pestis has two virulence plasmids, which code for a glycoprotein gel- like capsule called the F1 antigen and enzymes with phospholipase, protease, pathogenics. 5811 88- F1A.Keyantigen 5. I I fibrinolytic, and plasminogen-activating activity. ① have ③YOPS capsule & virulance plasmids Yersinia pestis also has its own adhesin similar to the invasins of the other Yersinia. 1. capsule key antigent gram-rebaccillae 8 Antigens: 3 the cell wall 2.0 antigen- Somatic antigen in 3. It antigen flagella Pathogenesis and Clinical Disease lymphatic sys. 1-($855.85' Organisms are carried by the lymphatic system from the site of inoculation to regional lymph nodes, where they are ingested by phagocytes. Y. pestis multiplies in these cells. Hematogenous spread of bacteria to other organs and 4 tissues may occur, resulting in hemorrhagic lesions at these sites. iss Perising 1125- Disease Cycles Sylvatic (wild) Urban (domestic) Reservoirs Rock squirrels Ground squirrels Prairie dogs Mice, voles Others Sylvatic Plague Enzootic Steady level of disease Low rodent mortality Mice and voles are probably significant enzootic reservoirs. Epizootic Increased rodent mortality Fleas seek out new hosts Expansion into human occupied areas Greatest threat to humans Urban Plague Infected fleas or rodents move into urban areas Domestic rodents infected High rodent mortality Fleas seek new host Domestic cats or humans Associated with poverty in humans Mode of Transmissions Flea bite Direct animal contact Tissues, body fluids, scratches, bites Enters through break in skin Aerosol Human cases April through November Increased activity of fleas and hosts Flea Vectors Can live off host for months Many species can serve as vector Oropsylla montana Rock squirrels, California ground squirrels, prairie dogs Most important flea vector in U.S. Xenopsylla cheopis Epidemics in Asia, Africa, South America Flea Transmission 27°C (80°F) Blood clots in gut of flea Y. pestis trapped Clotted blood regurgitated Enters wound from flea bite 27°C Blood clot in gut of flea dissolves Y. pestis passes through u Human Disease Three major forms of plague 128(x81/188-52,* Bubonic - - -5 Septicemic Pneumonic Primary Secondary Bubonic Plague Most common form ~80% of cases Incubation 2 to 6 days 1 week about Clinical signs pain ener ful Swollen, Fever, malaise, chills, headache Bubo: swollen, painful lymph node Mortality (untreated): 50-60% O  S Septicemic Plague 5s, 8's s => Bubonic plague 8 208505091: - %100 Primary or secondary Rapid onset Clinical signs Signs of sepsis ± bubo Necrosis of extremities Microthrombi block capillaries “Black Death” Mortality (untreated): 100%  Pneumonic Plague s$ 25. Septicemic is Incubation: 1 to 6 days Primary—Y. pestis inhaled Secondary—septicemic form spreads Clinical signs Fever, chills, headache, septicemia - is Respiratory distress, hemoptysis I ·is ↳ premonic plague s Person-to-person possible Potential use as bioweapon harmful biological agent  fever 2, Septicemic 95.ed2,5.I2* Manifestations The incubation period for bubonic plague is 2 to 7 days after the flea bite. the area between the abdomen and the upper thigh on either side of the body. Onset is marked by fever and the painful bubo, usually in the groin (bubo is from the Greek boubon for “groin”) or, less often, in the axilla. Without treatment, 50% to 75% of patients progress to bacteremia and die in gram-negative septic shock within hours or days of development of the bubo. About 5% of victims develop pneumonic plague with mucoid, then bloody sputum. Primary pneumonic plague has S a shorter incubation period (2-3 days) and begins only with fever, malaise, and a feeling of tightness in the chest. - Cough, production of sputum, dyspnea, and cyanosis develop later in the course. ~51 -- Death on the second or third day of illness is common, and there are no survivors without antibiotic therapy. A terminal cyanosis seen with pneumonic plague is responsible for the term Black Death. Even today, plague pneumonia is almost always fatal if appropriate treatment is delayed more than a day from the onset. -  SS SS. Skin ~ Sie 1*Bubonic side. A ·blood culture ($19); 3, 8, fever 8- i Laboratory Diagnosis Gategory A ( 5 gx ss5x;* Gram-stained smears of aspirates from the bubo typically show bipolar-staining gram- negative bacilli. An immunofluorescence technique is available in public health laboratories for immediate identification of smears or cultures. non-lactose fermenter is Hemolysis, 359shemolysis as s on the media is ↑ used for other members of the gram-veils MacConkey Jig& Yersinia pestis is readily isolated baccilli Enterobacteriaceae (blood agar, MacConkey agar), although growth may require more than 24 hours of incubation. breath inhale, 5 558,!X The appropriate specimens are bubo aspirate, blood, and sputum. 9ib,ginhalation (1 -;; Laboratories must be notified of the suspicion of plague to avoid delay in the bacteriologic diagnosis and to guard against laboratory infection. s18sei) - 5515 -> Blood agar Blood culture -58515. 58.83:8is.4 &media -18; 8,3 Growth, turbidity"s. 5-6-3 Bloodagar:8/5. 25, 295. 8. * E media II pi. 8 is 355.6 11. I colonies Sis. - Blood culture Treatment 8,8,146349958 Gentamicin or streptomycin with or without doxycycline is the treatment of choice for both bubonic and pneumonic plague. - 6 95158185:6209181 Ciprofloxacin or chloramphenicol (if meningitis is present) are ·ins'ssis CS7 201 s9! alternatives. Timely treatment reduces the mortality of bubonic plague to less than 10%, but the mortality rate of human cases of plague reported in developed countries is still around 20% because of delays in initiation immunocomprimised S of appropriate therapy. -S= = 5 - 39s * Prevention and Control Urban plague has been prevented by rat control and general public health measures such as use of insecticides. Sylvatic plague is virtually impossible to eliminate because of the size and dispersion of the multiple rodent reservoirs. Disease can be prevented by avoidance of sick or dead rodents and rabbits. Eradication of fleas on domestic pets, which have been known to transport infected fleas from wild rodents to humans, is recommended in endemic areas. The continued presence of fully virulent plague in its sylvatic cycle poses a risk of extension to the urban cycle and epidem ic disease in the event of major disaster or social breakdown. Chemoprophylaxis with doxycycline or ciprofloxacin is recommended for those who have had close contact with a case of pneumonic plague. It is also used for the household contacts of a person with bubonic plague, because they may have had the same flea contact. A formalin-killed plague vaccine once used for those in high-risk occupations is no longer available. References Yersinia & Plague Cynthia Nau Cornelissen & Marcia Metzgar Hobbs: Lippincott Illustrated Reviews: Microbiology. 4th Edition. 2020. Wolters Kluwer. Pages: 126-127. Kenneth J. Ryan, Nafees Ahmed, J. Andrew Alspaugh, et al. : Sherris Medical Microbiology. 7th Edition. 2018. McGrow Hill Education. Pages: 669-673. Any Questions???? Thank You