Microbiology Flagellates PDF

Microbiology Parasitology Flagellates Microbiology| Flagellates Contents : Intestinal Flagellates 3 Non pathogenic intestinal flagellates 14 Genital flagellates 20 Microbiology| Intestinal flagellates Giardia lamblia : Giardia was discovered by Leeuwenhoek in 1681 in his own stool but was not descri...

Microbiology Parasitology Flagellates Microbiology| Flagellates Contents : Intestinal Flagellates 3 Non pathogenic intestinal flagellates 14 Genital flagellates 20 Microbiology| Intestinal flagellates Giardia lamblia : Giardia was discovered by Leeuwenhoek in 1681 in his own stool but was not described until 1859 by Lambl. Geographical distribution : The highest prevalence of G. lamblia occurs in tropics and sub-tropical region where sanitation is poor. Microbiology| Intestinal flagellates Habitat It inhabits duodenum and the upper part of jejunum of man. Morphology : It exists in two forms: 1. Trophozoite 2. Cyst Microbiology| Intestinal flagellates Trophozoite : It is pear-shaped with rounded anterior and pointed posterior end The dorsal surface is convex, ventral surface it has sucking disc. It acts as an organelle of attachment. It lacks mitochondria Microbiology| Intestinal flagellates It is bilaterally symmetrical and has 1. one pair of nuclei, one on each side. 2. one pair of axostyles. 3. one pair of parabasal bodies present on the axostyles. 4. four pairs of flagella. 5. four pairs of blepharoplasts from which the flagella arise. Microbiology| Intestinal flagellates Cyst (transmission stage or the infective form) : Mature cyst is oval in shape and measures 11–14 μm× 7–10 μm in size. It has two pairs of nuclei which may remain clustered at one end or lie in pairs at opposite poles. Microbiology| Intestinal flagellates Life cycle (single host) : Man acquires infection by ingestion of cysts in faecally contaminated water or food. Within 30 minutes of ingestion excystation occurs in the duodenum. The cyst hatches out two trophozoites, which then multiply by binary fission to form enormous numbers and colonize in the duodenum and upper part of jejunum. Encystation occurs commonly in transit down the colon where the intestinal contents lose moisture and patient starts passing formed stools. Microbiology| Intestinal flagellates Pathogenicity (Giardiasis) : incubation period 1–4 weeks (average, 10 days). These flagellates do not invade the tissues, but feed on mucous secretions. parasite attaches itself to the surface of duodenum and jejunum, cause duodenal and jejunal irritation duodenitis and jejunitis. May causes traveller’s diarrhoea. Microbiology| Intestinal flagellates Symptoms : dull epigastric pain chronic diarrhoea of steatorrhoea type voluminous, foul smelling and contains large amount of mucus and fat but no blood When the parasite localizes in the biliary tract, it may lead to chronic cholecystitis and jaundice Microbiology| Intestinal flagellates Laboratory diagnosis : General Stool Examination (GSE) can identified the cysts in formed stool and the trophozoites in diarrhoeal stool by direct smear under the light microscope. The enzyme-linked immunosorbent assay (ELISA) to detect anti-Giardia antibodies in patients’ serum. Entero test (string test): aspirate specimens from the upper intestine by swallow a gelatin capsule, contains a spool of nylon string, to help it go down into stomach then (after 4-6 hrs.), the string will be pulled back up out of stomach through the throat and examined under a microscope. Microbiology| Intestinal flagellates Treatment : Metronidazole is an antibiotic that can cause nausea. Tinidazole often treats giardiasis in a single dose and is as effective as metronidazole. Furazolidone is a popular option for children. Non pathogenic intestinal flagellates Microbiology| Non pathogenic intestinal flagellates Chilomastix mesnili : occurs with other parasite infections. Inhabit in the human cecum and/or colon. Occurs in two stage (trophozoite and cyst) Microbiology| Non pathogenic intestinal flagellates Trophozoite (diagnostic stage) : Motility: Stiff, rotary 1 Nucleus Flagella: 3 anterior, 1 in cytostome Cyst (diagnositic stage) : Nucleus: Mature = 1 Cytostome Lemon-shaped Microbiology| Non pathogenic intestinal flagellates Life cycle : Infection occurs by the ingestion of cysts in contaminated water or food or by the fecal-oral route (via hands or fomites, i.e., inanimate objects such as towels that transmit infectious organisms to a host). In the large (and possibly small) intestine, excystation releases trophozoites (multiply by binary fission). Microbiology| Non pathogenic intestinal flagellates Trichomonas hominis – Troph : Motility: Jerky, rapid 1 Nucleus Flagella: 3-5 anterior, posterior Features Undulating membrane entire length inhabits the large intestine Microbiology| Non pathogenic intestinal flagellates Genus Trichomonas (no cyst stage) : has 3 distinct species: 1. T. hominis which inhabit large intestine & non pathogenic. 2. T. tenax which inhabit oral cavity & commensals. 3. T. vaginalis is the Urogenital pathogenic flagellate Genital flagellates Microbiology| Genital flagellates Trichomonas vaginalis : Common sexually transmitted protozoon. Geographical distribution: World wide Microbiology| Genital flagellates Morphology of Trophozoite stage : Average size 7-23X5-15μ Pear shaped Single vesicular Nucleus anteriorly & a small antero-lateral cytostome Thin axostyle midway crossed by thick parabasal body It lacks mitochondria Four anterior free flagella and a lateral marginal flagellum with an undulating membrane that reach to about half of the body length. No Cyst stage Microbiology| Genital flagellates Habitat : In the vagina and urethra of infected females. In the urethra and prostate of infected males. Microbiology| Genital flagellates Pathogenicity : mild vaginitis with discharge (contains a large number of parasites and leucocytes and is liquid, greenish or yellow). Male patients usually have mild or asymptomatic infections. itching and discomfort inside penile urethra, especially during urination. Microbiology| Genital flagellates In female sloughing of squamous epithelial cells of vagina and urethra Asymptomatic (50%): Profuse odorous (foul-smelling) discharge, burning, itching, frequency of urination and dysuria. On examination: Excessive discharge, diffuse vulval erythema Vaginal wall inflammation (Strawberry cervix) Microbiology| Genital flagellates The main mechanisms postulated seem to be mediated by cell to cell adhesion (critical step). Haemolysis. Excretion of soluble proteinases, pore-forming proteins and cell detaching factor Microbiology| Genital flagellates Laboratory diagnosis : The diagnosis of T. vaginalis cannot be readily made solely on the classic symptoms, because the clinical symptoms may be synonymous with those of other Sexual Transmitted Diseases (STDs). Diagnosis of trichomoniasis by microscopic examination considered most traditionally method. Microbiology| Genital flagellates Microscopic examination of wet film from discharge. Culture of discharge. (modified Diamond’s media). Detection of T.vaginalis antigen in discharge by: Enzyme immunoassay. Direct fluorescent antibody test. Detection of DNA of the parasite by Molecular techniques (PCR). Microbiology| Genital flagellates Treatment : Metronidazole, 2 g oral single dose tinidazole, 2 g oral single dose are highly effective against T. vaginalis infection.