Neisseria gonorrhea

Question 1

What are the most common STDs in the US

Answer 1

Chlamydia is most common, then gonorrhea

Question 2

List the pathogenic species of the Neisseriaceae family

Answer 2

N. gonorrhea, N. meningitidis, Moraxella catarrhalis

Question 3

What are the major bacteriological features (i.e. Gram stain, morphology) of Neisseria and Moraxella species that are useful in laboratory diagnosis?

Answer 3

Gram negative diplococcus. Single cocci are kidney shaped. Grow only on rich media in 5% CO2. Undergo rapid autolysis at 25C and alkaline pH.

Question 4

N. gonorrhea growth on chocolate agar, Thayer-Martin plates and Transgrow bottle

Answer 4

Chocolate agar is nonselective. Thayer Martin contains antibiotics. Transgrow bottle provides CO2

Question 5

N. gonorrhoeae antigenic heterogeneity

Answer 5

N. gonorrhoeae is antigenically very heterogeneous and capable of changing its surface structures (antigenic variation and phase variation) to avoid host defenses. Because there is so much antigenic variation by N. gonorrhoeae a single person can be infected with N. gonorrhoeae many times (>10X) in their lifetime

Question 6

N. gonorrhoeae virulence factors

Answer 6

1. pili- attach to mucosal epithelium. 2. Opa proteins- outer membrane proteins important for attachment and site/type of infection. 3. Lipo-oligosaccharide (LOS)- 8 or more types. Toxic for ciliated cells and responsible for inflammatory processes. 4. IgA protease- cleaves Fc of human IgA preventing opsonized bacteria from becoming phagocytosed. 2 types.

Question 7

antigenic variation and phase variation

Answer 7

Antigenic variation: There are hundreds of antigenic types of pili and opa proteins for N. gonorrhea. Change in the amino acid sequence of surface proteins via recombination causes this. Phase variation: The bacteria are capable of switching on and off the expression of pili and opa proteins

Question 8

Significance of antigenic variation and phase variation

Answer 8

Used by N. gonorrhea to avoid host defense mechanisms. A single cell can give rise to daughter cells with antigenically different pili, so the daughter cells are not recognized by Abs directed against the parent strain. But the daughter cells still cause same dz symptoms

Question 9

lower tract Diseases caused by N. gonorrhea

Answer 9

lower tract: cervicitis, abscess in glands next to vagina, urethritis.

Question 10

upper tract Diseases caused by N. gonorrhea

Answer 10

Upper tract: endometriosis, PID, epididymitis.

Question 11

Other sites affected by N. gonorrhea

Answer 11

Other sites: proctitis (more in gay men), pharyngitis, ophthalmia neonatorum (conjunctivitis in neonates), peritonitis and perihepatitis

Question 12

Disseminated forms of N. gonorrhea

Answer 12

Disseminated: dermatitis-arthritis-tenosynovitis syndrome, Monoarticular septic arthritis, Endocarditis (rare), meningitis (rare)

Question 13

Asymptomatic N. gonorrhea

Answer 13

Both men and women can be asymptomatic carriers, but the prevalence of asymptomatic carriers is much greater among women. asymptomatic infection particularly in women can lead to a more serious infections (e.g. pelvic inflammatory disease).

Question 14

gonorrhea in male- incubation, Sx, complications

Answer 14

2-5 day incubation. Urithritis (pain/burning during urination), purulent discharge, dysuria, PMN influx and shedding of epithelial cells. Complication: acute epididymitis

Question 15

gonorrhea in femlae- primary site, Sx/ time course

Answer 15

Primary site: cervix, urethra. Sx within 10 days- cervicitis, urethritis, vaginal discharge, dysuria. 50% are asymptomatic. Ascending infection can occur resulting in PID, fallopian tube scarring, infertility, ectopic pregnancy.

Question 16

Gonorrhea associated risks

Answer 16

increased risk of HIV or other STDS due to the inflammation associated with gonococcal infection.

Question 17

Diagnosis of N. gonorrhea

Answer 17

Need to distinguish N. meningitidis and N. gonorrhoeae from each other and from commensal Neisseria or Moraxella. Gram stain of urethral or endocervical exudates (or conjunctival exudates), culture, Oxidase production and oxidative utilization of carbs (GOLD standard), molecular testing,

Question 18

sensitivity vs specificity

Answer 18

specificity: negative test / true negatives. Sensitivity: positive test/ true positives

Question 19

What does the gram stain of N. gonorrhea show and what is the sensitivy/specificity

Answer 19

Gram negative diplococci WITHIN polymorphonuclear cells (PMNs). Sensitivity: 90% for men, 50% for women. Specificity: 99% for men, 90% for women. This is true only for urogenital infections with N. gonorrhoeae

Question 20

caveat of using gram stain to diagnose N. gonorrhea

Answer 20

Not sufficient to detect asymptomatic, endocervical, pharyngeal, or rectal infections

Question 21

Culture conditions for N. gonorrhea

Answer 21

Culture of the organism should be performed on enriched selective medium (eg, modified Thayer-Martin medium or chocolate agar), at 37°C in an atmosphere of 5% CO2 for 24-48 hours. N. meningitidis also grows at 5% CO2

Question 22

N. gonorrhea oxidase test and carb metabolism

Answer 22

positive oxidase test and the oxidative utilization of glucose, but not maltose or sucrose.

Question 23

N. meningitidis carb metabolism

Answer 23

oxidative utilization of glucose and maltose

Question 24

Moraxella Catarrhalis carb metabolism

Answer 24

No sugars are used

Question 25

Use of molecular testing for N. Gonorrhea

Answer 25

is becoming the new preferred method for detection due to high sensitivity/specifity and non-invasive method for collecting samples (urine or vaginal swabs)

Question 26

Tests to confirm N. gonorrhea in suspected sexual abuse

Answer 26

Adults: NAATs preferred regardless of penetration. Children: Culture remains the preferred method for urethral specimens or urine from boys and for extragenital specimens for all children. NAATs can be used as alternative to culture with vaginal specimens or urine from girls

Question 27

Which infection often co-occurs with N. gonorrhea infection

Answer 27

Chlamydia trachomatis- Pts with gonorrhea should often be treated for chlamydia as well

Question 28

Treatment of N. gonorrhea

Answer 28

250mg IM dose of ceftriaxone is most effective for genital and extragenital sites. 1g of azithromycin or doxycycline orally to cover co-pathogens. Doxycycline is less preferable due to increasing resistance. Oral cefixime ONLY if ceftriaxone is precluded (increasing resistance). If pt is allergic to cephalosporins, 2g of azithromycin may be used.

Question 29

Prevention of ophthalmia neonatorum

Answer 29

instillation of Silver Nitrate (2%) or topical erythromycin or tetracycline into eyes at birth. This is required by law in most states.

Question 30

Therapy for C. trachomatis

Answer 30

Macrolide or Tetracycline, Azithromycin (orally, single dose) or Doxycycline (orally 7 days)

Question 31

Treatment of ocular infection with N. gonnorheae

Answer 31

Ceftriaxone (IV or IM, single dose). Topical antibiotic alone is inadequate

Question 32

Treatment of ocular infection with C. trachomatis

Answer 32

Erythromycin (orally, 10-14 days). Topical antibiotic alone is inadequate

Question 33

Treatment of infected pregnant women with gonorrhea or chlamydia

Answer 33

gonorrhea: Third generation cephalosporins or spectinomycin (single doses). Chlamydia: Erythromycin (orally for 7 days) or Amoxicillin (orally for 7 days)

Question 34

What is the most significant emerging threat with regard to the treatment of gonococcal infections?

Answer 34

resistance- cephalosporins are the last line of defense for treating gonorrhea