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Flashcards in Bacterial STDs Deck (33)
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1

What is the most common bacterial STD in the US?

Chlamydia

Gonorrhea is number 2

2

Neisseriaceae characteristics

Gram negative diplococci

Aerobic

REQUIRES 5% CO2 for growth

Oxidase positive

Glucose only (N. gonorrhea), glucose and maltose (N. meningitidis), or glucose, maltose and lactose (N. lactamica)

Causes direct mucosal infection

3

Media for Neisseria

Chocolate agar or Thayer-Martin Chocolate Agar in CO2 incubator

NOT blood agar

4

Gonorrhea in male

90% have symptoms

Urithritis

Purulent discharge

Dysuria

Most common complication: acute epidyimitis

5

Gonorrhea in females

50% asymptomatic

Infection of cervix urethra

Vaginal discharge, dysuria

Ascending infection in 45%

PID, infertility, fallopian tube scarring, ectopic pregnancy

6

Disseminated gonorrhea

Swelling and pain in joints

Rash

Conjunctivitis

7

Virulence factors for gonorrhea

Pili: initiate binding to epithelial cells, antigenic and phase variation

Opa proteins (Outer membrane Proteins): important for intimate attachment. Antigenic and phase variation

IgA protease

8

What is antigenic and phase variation?

Antigenic: changing of amino acid sequence of surface proteins (one patient can have different pili from same infection!)

Phase: On-off control of expression of surface proteins

Both are used by N. gonorrhea to avoid host defense mechanisms

9

Antibiotic resistance of gonorrhea

Were very susceptible to penicillin, then had Beta-lactamase, then chromosomal mutations

Now cephalosporins are last line of defense for treating gonorrhea

10

Current guidelines for treatment of N. gonorrhea

Third generation cephalosporins plus azithromycin or doxycycline

NO more Quinolones (e.g. Ciprofloxacin)

Patients treated for N. gonorrhoeae should also be treated for Chlamydia trachomatis

Treat all sexual partners

11

Lipo-oligosaccharide (LOS)

N. gonorrhea

Equivalent of the lipopolysaccharide (LPS) of gram-negative bacteria, but without the long O-side chains.

8 or more types of LOS

Toxic for ciliated cells in tissue cultures. LOS is probably responsible for many of the inflammatory processes seen during an infection.

12

Diagnosis of N. gonorrhea

Gram stained smears of urethral or endocervical exudates reveal many 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. It is NOT true for other kinds of infection (e.g. oral pharyngeal infections).

Culture identification of N. gonorrhoeae including a positive oxidase test and the oxidative utilization of glucose, but not maltose or sucrose is the “Gold Standard” for laboratory diagnosis of gonorrhea.

13

Chlamydia

Obligate intracellular

Highly infectious/ very prevalent

Cocci/coccobacilli

Gram negative

VERY small (0.2-0.8 um diameter)

Dependent on host cell for ATP

14

What percent of men and women are asymptomatic with C. trachomatis

75% women
50% men

15

Comparison of incidence of gonorrhea, chlamydia, and syphillis in men vs women

Chlamydia: women have it more than men

Gonorrhea: equal in men and women

Syphilis: High rate in men and less in women

16

Symptoms of C. trachomatis

Impossible to distinguish from gonorrhea

17

What is the most common cause of neonatal conjunctivitis

C. trachomitis

18

Lymphogranuloma venereum

caused by C. trachomitis (serovariants L1-L3)

Sexually transmitted

Small ulcer disseminates to inguinal lymph nodes

Africa and S. America

19

Treatment for C. trachomitis

Azithromyin
or
Doxycycline

Treat partners

Not same problems with antibiotic resistance seen with gonorrhea

20

Chlamydia lifecycle

Biphasic

Elementary bodies (EB’s) measuring about 0.3 µm in diameter have a condensed chromosome and are the infectious form. EB’s can be recognized by their electron-dense centers. EB’s enter the cell by endocytosis.

Reticulate bodies (RB’s), which measure 1 µm in diameter, are the vegetative forms that multiply intracellularly. RB’s develop within the membrane-bound vacuole through a process of metabolic changes and reorganization of chromosome. The molecular basis of this process is not understood. Energy for replication is derived from the ATP generated by the host cell.

After 24 to 72 hours of intracellular growth, RB’s reorganize and condense to form multiple new EB’s. The host cell ruptures and frees the EB’s, which are capable of infecting other host cells.

21

Trachoma

Caused by C. trachomitis

Chronic keratoconjunctivitis that begins with acute inflammatory changes in the conjunctiva and cornea and progresses to scarring and blindness.

Hand to eye contact

22

Inclusion conjunctivitis

Caused by C. trachomitis

Inclusion conjunctivitis is an acute disease that occurs throughout the world in both infants and adults. It is the most common form of neonatal conjunctivitis in the United States.

23

What is the most frequently reported infectious disease in the US?

C. trachomitis

24

What is the most sensitive and specific test for C. trachomitis right now?

NUCLEIC ACID AMPLIFICATION TECHNIQUES (NAAT)

25

Chlamydial cell wall

NO muarmic acids

26

How can you visualize chlamydia?

Giemsa stain

27

What do the different serotypes of C trichomitis cause?

A-C: blindness
D-K: STI
L1-L3: LGV

28

Spirochetes

spiral, motile bacteria

Gram-negative but don't have LPS

Reproduce by transverse fission

Pathogenic treponema Can't culture in vitro

29

Four stages of syphilis

Primary: Primary lesion or chancre (usually painless). Can test seronegative for syphilis. Highly infectious.

Secondary: Several weeks after primary chancre. Mucocutaneous lesions. High titer serologic tests. Alopecia. Condylomata lata. Lesions ARE infectious.

Latent: No symptoms, but serum positive.

Tertiary: 30% untreated pts progress to tertiary syphillis in 1-20 years. Sero-positive. Due to immune response. Gummatous lesions, cardiovascular syphilis, neurosyphilis. Lesions are NOT infectious.

30

Neurosyphilis

Can occur at any stage of syphilis

Clinical manifestations can include acute syphilitic meningitis, meningovascular syphilis, and ocular involvement