gram positive rods (Non spore forming)

gram positive rods, Non spore forming, CORYNEBACTERIUM DIPHTHERIAE
LISTERIA MONOCYTOGENES
GARDNERELLA VAGINALIS
Diphtheria and TRANSMISSION PATHOGENESIS
CLINICAL FINDINGS
TREATMENT
PREVENTION
LESTERIA CONTAMINATED
FOOD

1. NON SPORE FORMING GRAM POSITIVE RODS Presented by SYEDA MARYAM

2. IMPORTANT PATHOGENS 3 important pathogens in this group CORYNEBACTERIUM   DIPHTHERIAE LISTERIA MONOCYTOGENES GARDNERELLA VAGINALIS

3. CORYNEBACTERIUM DIPHTHERIA Gram positive rods Appear club shaped Arranged in palisades or in V or L shaped Rods are in form of beads Beads consist of granules of highly polymerized polyphosphate

4. DISEASE Diphtheria Other corynebacter are implicated in opportunistic infections TRANSMISSION Humans are the only natural resource Resides in the upper respiratory tract and transmitted by air born droplet Can also infect skin at pre existing lesion

5. PATHOGENESIS Organism is first establish and maintain itself in throat Diphtheria toxin inhibits protein synthesis by ADP- ribosylation of elongation factor (EF-2) Toxin effects all eukaryotic cells but has an effect on prokaryotic cells 2 functional domains of toxin binding domain binding of toxin on cell memb . Active domain enzymatic activity that cleaves down nicotinamide f rom NAD DNA code for Diphtheria toxin part of DNA temperate phage Beta phage

6. CLINICAL FINDINGS Most prominent sign thick gray adherent pseudo membrane over the tonsils and throat 3 prominent complications are Extension of the membrane into larynx and trachea air way obstruction Myocarditis accompanied by arrhythmias and circulatory collapse Nerve weakness and paralysis esp. of cranial nerves Peripheral neuritis affecting muscles of extremities also occur Cutaneous diphtheria causes ulcerating skin lesions covered by grey membrane

7. LABORATORY DIAGNOSIS Involves both isolating organism and demonstrating toxin production A throat swab should be cultured on Loffler’s medium , a tellurite plate and a blood agar If diphtheria is reused from cultures ,either animal inoculation or an antibody based gel diffusion precipitation test is prepared to document toxin production PCR assay can also be used Smear of the throat swab should be stained with gram stain and methylene blue tapered pleomorphic gram positive rods can be suggestive

8. TREATMENT The treatment of choice is anti toxin which should be given immediately on the basis of clinical impression Toxin binds rapidly and irreversible to cells . Once bound can't be neutralized Function of anti toxin is to neutralize unbound toxin in blood Treatment with penicillin G or erythromycin is also recommended

9. PREVENTION Children are immunized with diphtheria toxoid Diphtheria toxoid is prepared by treating exotoxin with formaldehyde , which inactivates the toxin toxicity but antigenicity remains intact Immunization consists of three doses given at 2 4 6 months age

10. LISTERIA MONOCYTOGENES Arranged in V or L shaped Exhibits unusual tumbling movement that distinguish it from carynebacteria which are non motile Colonies on blood agar plate produce a narrow zone of Beta hemolysis Listeria grow well at cold temperature , so contaminated food in refrigerator can increase the risk the of gastroenteritis growth is called cold enhancement DISEASES Causes meningitis and sepsis in new born, pregnant women , immunocompromised patient

11. PATHOGENESIS Infection occur in 2 clinical condition In fetus or in new born In placenta or during delivery In pregnant women and immunocompromised patients Organism is distributed in animals soil and plants transmitted to human by ingesting pasteurized milk , under cooked meat , raw ve getables Following ingestion bacteria enters colon and to female genital tract Invasion of cells is mediated by internal in made by Listeria and adhesion on the surface of human cells Organism produce Listeriolysin allows it to escape from phagosome into cytoplasm Cell mediated immunity is more imp. Than humoral immunity Move from one human cells to another by actin rockets filaments

12. LESTERIA CONTAMINATED FOOD

13. CLINICAL FINDINGS Infections during pregnancy cause abortions , premature delivery or sepsis during prepartom period New born infected at the time of delivery can have acute meningitis 1 – 4 weeks later Infection in immunocompromised adults can sepsis of meningitis Gastroenteritis is characterized by watery diarrhea fever headache myalgia and abdominal cramps but little vomiting caused by contaminated diary products and under cooked meat

14. LABORATORY DIAGNOSIS Made by gram stain and culture Formation of smell gray colonies with a narrow zone of Beta hemolytic on blood agar plate suggests presence of listeria Identification of the organism as L. monocytogenes is made by sugar fermentation test

15. TREATMENT Consist of ampicillin with or without gentamycin   Trimethoprim , sulfonamide can also be used Listeria gastroenteritis typically doesn’t require any treatment

16. PREVENTION Limiting the exposure to potential sources such as farm animals unpasteurized milk products and raw vegetables is recommendable Trimethoprim sulfamethoxazole to prevent pneumocystis pneumonia can also prevent listeriosis

17. GARDNERELLA VAGINALIS Small facultative Gram variable rods Gram variable refers to some organism that are some purple and others are pink Wall is thin and older organism tend to loose the purple color

18. DISEASE Cause bacterial vaginosis but no vaginitis PATHOGENESIS Gardenral vaginalis after found in association with anaerobes and nonaerobes Bacterial vaginosis is not transmitted by sexual activity It is considered to be a dysbiosis in which lactobacillus that are found as normal flora in the vagina is replaced by those organism

19. CLINICAL FINDINGS Bacterial vaginosis is characterized by a malodorous , white or gray colored vaginal discharge Discharge has characteristic fishy odor Inflammatory changes are typically absent which is why it is called vaginosis rather than vaginitis Mild itching may occur

20. LABORATORY DIAGNOSIS Based on the clue cell ( vaginal epithelial cells covered with bacteria ) in microscopic examination of vaginal discharge Whiff test treating vaginal discharge with 10% KOH and smelling pungent , fishy odor is positive A pH of greater than 4.5 of vaginal discharge indicates bacterial vaginosis TREATMENT AND PREVENTION Drug metronidazole There is no vaccine

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