Mycoplasma Mycoplasma pneumoniae K R.pptx

Mycoplasma K R.pptx

1. Mycoplasma. K R MICRO NOTES 1

2. Classification. DOMAIN : Bacteria PHYLUM : Tenericutes CLASS : Mollicutes ORDER : Mycoplasmatales FAMILY : Mycoplasmataceae GENUS : Mycoplasma K R MICRO NOTES 2

3. Introduction. The genus mycoplasma consists of group of very small, highly pleomorphic organism. They may be saprophytic, parasitic or pathogenic. They are gram negative, previously called pleuropneumonia like organism (PPLO). They are characterized by the absence of cell wall and therefore of varying shapes and sizes. K R MICRO NOTES 3

4. Morphology. They are the smallest of cellular microorganism. Measuring 0.2- 0.3 micrometer in diameter rarely exceeding 1 micrometer. Poorly stained in gram staining and stained well in giemsa stating. Reproductory method is not fully understood but may be: By development within filament of elementary body and their release. By binary fission. By budding. K R MICRO NOTES 4

5. Culture characteristics. They are facultative anaerobes growing better aerobically. Parasitic stain grows optimally at 35 to 37 ̊ C. Media of their cultivation is heart infusion broth with 2% agar(pH 7.8) enriched with 30% horse serum and yeast extract. Colonies appear after 2 to 3 days incubation and are 10 to 1000 micro in size. The colonies have fried egg appearance, central opaque granular area of growth surrounded by flat translucent peripheral zone. Subculture is done by cutting out an agar block with colonies and rubbing it on fresh plate. These are mostly hemolytic. K R MICRO NOTES 5

6. Mycoplasma pneumoniae. These organism are short filament, 0.2 to 0.5 micrometer in length. They grow more slowly than most other mycoplasma, it colonies appearing 5 to 10 days after inoculation. It is also called “walking pneumoniae”. K R MICRO NOTES 6

7. Morphology. It is gram negative smallest pleomorphic free living organism which is non-motile. This method of reproduction is not fully understood but may be: By development within filaments of elemenatary body and their release. Binary fission. By budding. K R MICRO NOTES 7

8. Culture characteristics. They are facultative anaerobes growing better aerobically. Parasitic stain grows optimally at 35 to 37 ̊ C. Media of their cultivation is heart infusion broth with 2% agar(pH 7.8) enriched with 30% horse serum and yeast extract. Colonies appear after 2 to 3 days incubation and are 10 to 1000 micro in size. The colonies have fried egg appearance, central opaque granular area of growth surrounded by flat translucent peripheral zone. Colonies cannot be picked up with platinum loop. Subculture is done by cutting out an agar block with colonies and rubbing it on fresh plate. These are mostly hemolytic. K R MICRO NOTES 8

9. Biochemical reaction. Most species utilize glucose or araginase as main source of energy. Urea is not hydrolyzed. They are not proteolytic . K R MICRO NOTES 9

10. Pathogenicity. Incubation period is 1 to 3 weeks. It is self limited disease with recovery in 1 to 2 weeks. The disease is world wide and transmission is by droplets of nasopharyngeal secretions. It is common in older children and adolescents. Onset is slow with fever, malaise, headache, and sore throat followed by paroxysmal cough with blood tinged sputum and radiological evidence of consolidation lungs. K R MICRO NOTES 10

11. Epidemiology. In 1994, scientists discover the agent that cause “atypical” pneumonia, later named as Mycoplasma pneumoniae . They first thought it was a virus or fungus so they chose the name “mycoplasma”, which is Greek for “fungus – formed”. Eventually, scientists learned that it is a bacterium with many unique characteristics. Mycoplasma pneumoniae is a common cause of respiratory tract infection, especially in children. Pneumoniae infections probably occur throughout the world. It has been estimated that approximately 50% of the infections in adults but only 20% in children are completely asymptomatic. Mycoplasma pneumoniae is spread from person to person from respiratory droplets, such as when someone coughs or sneezes. K R MICRO NOTES 11

12. Disease patterns. M. pneumoniae infections are common in the united states. The number of infections varies over time, with peaks of disease every 3 to 7 years. An estimated 2 million cases of M. pneumoniae infections occur each year in the united states. However, many infections are not diagnosed, so the actual number is likely higher. From 2006 to 2010, the annual distribution of M. pneumoniae infections was 13.40%, 5.39%, 6.36%, 14.58% and 13.99%, respectively. There was a significant difference between different years and seasons. K R MICRO NOTES 12

13. Symptoms. A persistent cough that may come in fits throughout the day Flu-like symptoms, such as fever, chill, or cold sweat. A sore, dry, or itchy throat. A persistent headache. Weakness or fatigue. Chest pain when breathing deeply. Aches and pains in the muscles and joints. K R MICRO NOTES 13

14. Laboratory diagnosis. culture: Mycoplasmas can be cultured from sputum and throat swabs using special enriched media. Growth may be achieved aerobically on a soft agar surface. Inhibitors of bacterial growth(thallium acetate, penicillin) are routinely added to the media. Growth is slow, and media are usually observed for three to four weeks before being called negative. Colonies are small, and agar plates must be scanned microscopically with oblique lighting for detection of growth. K R MICRO NOTES 14

15. 2. Serology : Streptococcus MG agglutinin occurs in about 2.5 % of cases of M. pneumonia infection. Serial dilution of unheated serum of patient and heat killed suspension of streptococcus are mixed. A titre of 1: 20 or over is considered suggestive. 3. Cold agglutinin test : The cold agglutinin test is based on the appearance in a high proportion of cases with primary a typical pneumonia, of macroglobulin antibodies that agglutinate human group O erythrocytes at low temperature. For the test, serial dilutions of patients serum are mixed with an equal volume of a 0.2% washed human O group erythrocytes and clumping observed after leaving at 4 ̊ C overnight. The clumping is dissociated at 37 ̊ C. About two thirds of patients with M. pneumoniae pneumonia will develop cold agglutinins. K R MICRO NOTES 15

16. 4. Specific antibody test : Serological diagnosis may be carried out by using mycoplasma antigens. Each will detect increases in antibody titre in appropriately collected sera from 80% or more of persons infected with M.pneumoniae . K R MICRO NOTES 16

17. Treatment. Tetracycline and erythromycin is the drug of choice for treatment. It is resistant to penicillin. K R MICRO NOTES 17

18. Prophylaxis. Avoid close contact. Cover your mouth and nose with a tissue when you cough or sneeze. Put your used tissue in a waste basket. Wash your hands often with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand rub. K R MICRO NOTES 18

19. Besides M. pneumoniae , many other mycoplasma species have been isolated from man. M. hominis has been reported to cause pharyngitis and pelvic infections. Mycoplasma genitalium , is a sexually transmitted, small and pathogenic bacterium that lives on the mucous epithelial cells of the urinary and genital tracts in humans. K R MICRO NOTES 19

20. Reference. Textbook of medical microbiology – Satish Gupte. Practical medical microbiology – J. G. Collee, A.G. Fraser , B.P. Marmion, A. Simmons. Textbook of medical microbiology – H. L. Chopra. Medical microbiology – C.G.A. Thomas. Introduction to Medical microbiology – R Ananthnarayan. Textbook of medical microbiology – ananthnarayan , panikar . K R MICRO NOTES 20

21. Thank you. K R MICRO NOTES 21