Lecture 9 Flashcards

Question

Gonorrhea: Modes of Transmission

Answer 1

Sexual Intercourse: * Vaginal or anal sex with infected partner * Oral sex Without Sexual Intercourse: * Touching infected parts with fingers e.g. eyes * From mother to baby at birth * Incubation Period: * 1- 14 days

Answer 2

80-90% infected males show symptoms: * Men with asymptomatic urethritis are an important reservoir for transmission * White, yellow or green thick discharge of pus from tip of penis * Urethral itch and pain or burning sensation when passing urine * Disease can heal spontaneously * Complications in Males: * Scarring of urethra: blockage of urine flow * Infection of testes: sterility * Scarring of vas deferens: sterility * Dissemination to joints, heart, pharynx

Answer 3

Disease in females more insidious * only 50% show symptoms * In vaginal region, only cervix infected * Strong smelling vaginal discharge, either thin and watery or thick and yellow * Pain or burning sensation when passing urine * Complications: * Pelvic Inflammatory Disease * Ophthalmia neonatorum

Answer 4

In 15% of infected woman Gonococci ascend from the cervix to the fallopian tube all the way to the pelvic peritoneum. Bacteria can cause inflammation Scarring of fallopian tube can result in their blockage Reduced fertility or infertility Ectopic pregnancy-Life threatening

Answer 5

Exposure of infant to infected secretions in birth canal * Ocular infections of newborn with N. gonorrhoea

Answer 6

eyes of newborns treated with tetracyline, erythromycin or 1 % AgNO2 Keratoconjunctivitis occasionally in adults after autoinoculation: * corneal scarring

Answer 7

Adherence due to pili mediate binding to mucosal cells of the cervix and urethra. Evasion of host defenses due to IgA protease and change of pili variant overtime(antigenic variation) Cell damage as lipopolysaccharides cause inflammation

Answer 8

In males: Gram stained smear of pus from urethra gram negative diplococci in phagocytotic leukocytes In females: Cultivation of bacteria on Thayer Martin or Chocolate Agar Novel Detection Methods: * ELISA to detect gonococci * Monoclonal antibodies against gonococcal surface protein * DNA probes against gonococci

Answer 9

Sharp decrease in cases after introduction of penicillin Increase of cases after introduction of birth control pills. Results in decreased glycogen production in vaginal region Lactobacilli usually grow on glycogen and convert it to lactic acid Reduced glycogen production leads to increased pH in vaginal region At higher pH gonococci have a better chance of growing and proliferating in genital region.

Answer 10

Azithromycin--> class of macrolides subclass of azalides; single or two oral doses Ceftriaxone--> Cephalosporin; one intramuscular injection Doxycycline (tetracycline): two doses per day for one week; also kills chlamydia

Answer 11

* Public education * Condoms and prompt treatment * Cases have to be reported * No vaccine

Answer 12

C. trachomatis: Causes urogenital infections, trachoma, conjunctivitis, and pneumonia. Noted as a sexually transmitted disease. C. pneumoniae: Causes bronchitis, sinusitis, pneumonia, and possibly contributes to atherosclerosis. Transmission occurs through airborne infection. C. psittaci: Causes pneumonia, specifically known as psittacosis. Transmission also occurs through airborne infection.

Answer 13

Small obligate intracellular pathogens * once considered to be viruses * Possess an inner and outer membrane similar gram-negative bacteria but do not have a peptidoglycan layer * Although synthesizing most of their metabolic intermediates, they are unable to generate their own ATP energy parasites

Answer 14

Only infecting humans (one strain infecting mice) * Appr. 127 Mio cases / year worldwide * major cause of human eye and genital disease * significant cause of blindness worldwide * transmission by vaginal, anal or oral sex, and from mother to baby during birth

Answer 15

Infects human columnar epithelial cells

Answer 16

Elementary Bodies Small (0.3-0.4 micrometer) infectious form and metabolically inactive. Have a rigid membrane as outer exterior to resist harsh outer environment conditions of the eukaryotic cells. bind to receptors of host cells to initiate infection. Reticulate Bodies: Noninfectious intracellular form Metabolically active replicating form fragile membrane lacking extensive disulphide bonds

Answer 17

Binding of EBs to host cell receptors * Internalization by phagocytosis * Reorganization to become RBs * Inhibition of fusion of phagosome with lysosomes * Replication and reorganization into EBs * Between 100 - 500 progeny * C. psittaci: lysis of cells * C. trachomatis and C. pneumoniae: extrusion by reverse endocytosis

Answer 18

Approximately 35 - 50% of nongonococcal urethritis due to C. trachomatis * Clinical manifestations from destruction of cells and host inflammatory response * Infection does not stimulate long lasting immunity * reinfection results in an inflammatory response and subsequent tissue damage * In appr. 80% of females infection asymptomatic * In only 25% of males infection asymptomatic

Answer 19

* Trachoma from greek meaning rough which characterizes appearance of conjunctiva * Chronic infection or repeated reinfection results in inflammation of entire conjunctiva * Scarring of conjunctiva causes turning in of eyelids and eventual scarring, ulceration and blood vessel formation in cornea results in blindness Inflammation also interferes with flow of tears * important antibacterial defense mechanism secondary bacterial infections

Answer 20

Treponema Pallidum

Answer 21

Treponema (Greek): twisted thread pallidum (Greek): pale * Spirochete: * Gram negative, long, thin, helical * Motile: rapid rotation about its longitudinal axis * Locomotion by axial filaments

Answer 22

* flagella between peptidoglycan layer/outer membrane * run parallel to cell body * movement by twisting of cell body

Answer 23

For research purposes cultivated in rabbits * Not possible to grow over longer periods in culture * viable organism can be maintained for 18 to 21 h in complex media * narrow optimal ranges of pH (7.2 to 7.4) and temperature (30 to 37°C) Culture of Treponema pallidum * Rapidly inactivated by mild heat, cold, desiccation, and most disinfectants * Long generation time (30 h)

Answer 24

* Treponemal infections in distinct clinical stages: * Primary stage: * Multiplication of bacteria at initial site of entry * Secondary stage: * Dissemination of treponemes to other tissues * Tertiary stage: * After prolonged period, up to 30 years, immune reactions of body, affecting cardiovascular or central nervous system Treponema pallidum: Pathogenesis * Penicillin treatment effective on all stages of syphilis * No vaccine

Answer 25

1 out of three people exposed gets infected Development of symptoms 10-60 days after exposure to Treponema pallidum Development of solitary and painless sore --> chancre at the site of infection On penis, labium, anorectal region, or around the mouth Healing of chancre within 4-6 weeks even without treatment Progression of syphillis to secondary stage if not treated in primary stage

Answer 26

1-6 weeks after healing of chancre red rashes or sores on palms of hands and soles of feet or all over the body Rash accompanied by fever , sore throat, headaches, joint pains, poor appetite, weight loss and hair loss superficial sores may occur on mouth vagina or anus sores contagious 2-6 weeks after onset of secondary syphillis host defences bring about healing about 25% of patients experience recurrence of secondary stages in the first several years of infection

Answer 27

Without treatment of primary or secondary stage, < 50% of cases progress to tertiary stage * Most symptoms due to host immune reactions * Development of lesions, called ´gummas´ * rubbery masses of tissue in organs or on skin * ulceration causes extensive tissue damage * can affect cardiovascular or central nervous system * weakening of aorta * loss of motor control, personality changes, blindness

Answer 28

Diverse group of DNA-based viruses * 118 different HPV types * Infection of skin and mucous membranes of humans and variety of animals * Some HPV types cause warts on skin * transmission by skin to skin contact * Group of about 30-40 HPVs typically transmitted through sexual contact and infection of anogenital region * About 25% of all women aged < 30 years infected

Answer 29

* Some types cause genital warts * Other types do not cause any noticeable signs of infection * Persistent infection with a subset of about 13 so-called "high-risk" types * different from the ones that cause warts * may lead to precancerous lesions ev. progression to cancer * HPV infection necessary factor in development of nearly all cases of cervical cancer

Answer 30

Most HPV infections rapidly cleared by immune system * no progression to cervical cancer * Slow process of transforming normal cervical cells into cancerous ones * occurring of cancer in people who have been infected with HPV for long time, usually over a decade or more * History of infection with one or more high-risk HPV types prerequisite for development of cervical cancer * women with no history of HPV infection do not develop cervical cancer

Answer 31

High risk types--> Are type 16, 18, 31 and 45 which are HPV virus can lead to cervical cancer, anal cancer, vulvar cancer, and penile cancer * HPV-induced cancers often have viral sequences integrated into cellular DNA * HPV oncogenes E6 and E7 promote tumor growth

Answer 32

High-risk types 16 and 18 cause 65% of cervical cancer * High-risk types 31, 33, 45, 52 and 58 cause 20% of cervical cancer * HPV types 6 and 11 cause 90 percent of genital warts * Gardasil, prophylactic HPV vaccine, marketed by Merck * protection against high-risk types 16 and 18, and against genital wart types 6 and 11 * Gardasil 9, approved in 2014, marketed by Merck * protection against high-risk types 16, 18, 31, 33, 45, 52 and 58 * protection against genital wart types 6 and 11 * Cervarix, prophylactic HPV vaccine, marketed by GlaxoSmithKline * protection against high-risk types 16 and 18

Answer 33

HIV is retrovirus with single-stranded RNA, reverse transcriptase, and a phospholipid envelope with gp120 spikes * HIV spikes attach to CD4+ and coreceptors on host cells; CD4+ receptor is found on T helper cells, macrophages, and dendritic cells.

Answer 34

* Co-receptors and HIV infection * CCR5 and CXCR4 are chemokine receptors * Cells with homozygous mutant CCR5 molecules are not infected by HIV * 1-3 in 100 Caucasians * No Africans * Persons with heterozygous mutant CCR5 molecules progress to AIDS more slowly * 25% of long term survivors are CCR5 mutants (deletions) * The same CCR5 mutation (called “delta 32”) is thought to be the mutation that rendered some people immune to plague in the middle ages

Answer 35

Mechanism of viral entry 1. Initial interaction between gp120 and CD4. 2. Conformational change in gp120 allows for secondary interaction with CCR5. 3. The distal tips of gp41 are inserted into the cellular membrane. 4. gp41 undergoes significant conformational change; folding in half and forming coiled-coils. This process pulls the viral and cellular membranes together, fusing them.

Answer 36

Fusion of HIV virus envelope with cell membrane * Viral RNA transcribed to DNA by reverse transcriptase. * Viral DNA becomes integrated into host chromosome to direct synthesis of new viruses or to remain latent as a provirus.

Answer 37

* HIV evades the immune system in latency: * inactive provirus * fully assembled virions in vacuoles * HIV may also escape immune system by using cell–cell fusion and by antigenic change.

Answer 38

1. Acute and Asymptomatic Phase (appr. first three years) * Within first few months high virus titer (up to 10 million viruses per ml blood) and fall in CD4+ cells but recovery of numbers * After 2-3 months antibodies against HIV in blood * HIV titer in blood between 1000 to 10,000 per ml 2. Symptomatic Phase; early indications of immune failure * At least 100 billion HIVs generated each day; appr. 1 Mio mutated viruses generated per day * About 2 billion CD4+ cells produced per day to compensate for losses; Daily loss of about 20 million CD4+ cells per ml 3. AIDS Phase: CD4+ T-cell numbers have declined to less than 200 CD4+ cells/µl * Without medication progression from HIV infection to AIDS takes about 10 years; with early onset of medication appr. normal life expectancy

Answer 39

Diagnosis * Seroconversion takes up to 3 months * HIV antibodies detected by ELISA * HIV antigens detected by Western blotting * RT-PCR for the detection of the retroviral RNA * Prevention * Use of condoms * Use of sterile needles (IDUs) * Health care workers use gloves, gowns, and masks

Answer 40

Membrane: host derived * Three structural genes: gag – pol –env * gag: group specific antigen * pol: polymerase * env: envelope * Three polypeptides

Answer 41

p17: inner surface p24: nucleocapsid p9: nucleocapsid associated with RNA Retrovirus Polyprotein

Lecture 9 Flashcards

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