Pathophysiology: STIs Flashcards
What are Sexually Transmitted Infections? (STI’s)
sexual contact that result in pathogen spread
Overall STI epidemiology and Etiology
- 1 in 5 people in the US
- 20,000 women become infertile each year due to undiagnosed infections
- $16 billion annual direct medical costs for new infections
What is the most common STD in the US?
a) Chlamydia
b) Gonorrhea
c) Syphilis
d) Herpes
a) Chlamydia
- 1.6 million cases (2020)
- 1.2% decrease since 2016
Herpes Simplex Virus (HSV) and Statistics:
- ~50 million in the US are infected by genital herpes
- seroprevalence of HSV2 in those age 14 to 49 years = ~12%
Trichomoniases Statistics
- ~3.7 million cases per year
- prevalence estimated to be 2.1% in females and 0.5% in males
What are the Risk factors and Determinants of Frequency for STI’s?
- number of sexual partners
- unprotected sexual activities
- age
- prostitution
- illicit drug use
- health disparities
STI Complications
- more frequent and more severe in women
- damage to reproductive organs
- increased risk of cancer
- pregnancy complications
- transmission of disease to fetus or newborn
- increased risk of HIV transmission
Which pathogen causes Gonorrhea
Neisseria gonorhoeae
Does gonorrhea stain gram positive or gram negative?
stains gram negative diplococcus
Neisseria gonorhoeae
- gram negative diplococcus
- grows best in warm, mucus secreting epithelia
Gonorrhea: Pathophysiology
1) Gonococci attach to cell membranes of mucosal epithelium by surface pili
2) N. gonorrhoeae penetrates through epithelial cells to submucosal tissue
3) Mucosal damage occurs (sloughing of epithelium)
4) Polymorphonuclear (PMN) leukocytes invade the tissue
5) Submucosal abscesses form and purulent exudates (pus) are secreted
Where does Gonococci attach to?
it attaches to cell membranes of mucosal epithelium by surface pili
What is N.gonorhoeae’s MOA?
it penetrates through epithelial cells to submucosal tissue
What happens when gonococci aka N.gonorrhoeae enters through the submucosal tissue?
mucosal damage occurs (sloughing of epithelium)
What kind of other foreign materials invade the tissue in Gonorrhea?
Polymorphonuclear (PMN) leukocytes invade the tissue
What is the incubation period for Gonorrhea in males?
1-14 days
what is the incubation period for Gonorrhea in females?
1-14 days
When is the symptom onset of Gonorrhea for males?
- 2-8 days
When is the symptom onset of Gonorrhea for females?
10 days
What is the most common site of infection of Gonorrhea for males?
Urethra
What is the most common site of infection of Gonorrhea in females?
Endocervical canal
Where are the other sites of infection of Gonorrhea in males?
rectum, eye, oropharynx
Where are other sites of infection of Gonorrhea in females?
urethra, eye, rectum, oropharynx
What are the symptoms of Gonorrhea in males?
- Urethral infection: dysuria, urinary infection
- Anorectal infection: severe rectal pain
- Pharyngeal infection: mild pharyngitis
What are the signs of Gonorrhea in males?
- purulent urethral or rectal discharge (scant to profuse)
- anorectal: pruritis mucopurulent discharge, bleeding
What are the symptoms of Gonorrhea in females?
- Endocervical infection: asymptomatic to mildly asymptomatic
- Urethral infection: dysuria, urinary frequency
- Anorectal and pharyngeal infection: same as for males
What are the signs of Gonorrhea in females?
- abnormal vaginal discharge
- uterine bleeding
- purulent urethral or rectal discharge (scant to profuse)
What are the complication of Gonorrhea in males?
- Rare: Epididymitis, prostatitis, inguinal lymphadenopathy, urethral stricture
- disseminated gonnorrhea
What is 3x more likely in females than males (Gonorrhea complication)?
disseminated gonorrhea
What are Gonococcal complications in females?
- pelvic inflammatory disease
- disseminated gonorrhea
pelvic inflammatory disease
- may lead to ectopic pregnancy
- infertility
- 15% of cases
What is the Gonococcal infection in pregnancy?
- neonates may go through the birth canal during passage
- neonatal conjunctivitis
Neonatal conjunctivitis
- aka ophthalmia neonatorum
- may result in blindness if not treated promptly
What is the diagnosis for Gonorrhea?
- the use of Nucleic acid amplications tests (NAAT’s)
- cultures
- Gram stain
- screening
Nucleic acid amplications tests (NAAT’s) for Gonorrhea
- most sensitive
- use endocervical, vaginal, urethral (for men only), or urine specimens
- also from rectal or pharyngeal specimens
- self-collected specimens (vaginal, urine, rectal, or pharyngeal)
- point-of-care (POC) NAATs also available
- NO antimicrobial susceptibility testing
Cultures (Gonorrhea)
- Females: endocervical
- Males: urethral
- use for suspected treatment failure
Gram stain (Gonorrhea)
- used for males with symptomatic urethritis (discharge)
(Gonorrhea) Screening recommended for:
- sexually active women <25 years of age
- men and women at risk
What is the cause of Chlamydia?
- caused by Chlamydia trachomatis
Chlamydia trachomatis
- obligate intracellular bacterium
- shares properties of viruses and bacteria
What is required for Chlamydia trachomatis for replication?
- requires material from host cells for replication, but maintains cellular identity throughout the development
Chlamydia trachomatis cellular characteristics
- do NOT have a cell wall peptidoglycan
Describe the outer membrane of Chlamydia trachomatis
- it is similar to a gram negative bacteria
How many forms does Chlamydia exists in?
Two form:
- the Elementary body (EB)
- the Reticulate Body (RB)
Elementary bodies (EBs)
- are infectious particles
- capable of entering uninfected cells
- they are adapted for extracellular survival
Reticulate Bodies (RBs)
- not infectious
- metabolically active and can replicate
- adaptive for intracellular survival
Chlamydia:
How long does incubation period take in males?
- 35 days
Chlamydia:
How long does incubation period take in females?
7-35 days
Chlamydia:
Symptom onset in males
7-21 days
Chlamydia:
Symptom onset in females
7-21 days
Chlamydia:
Most common site of infection for males
- Urethra
Chlamydia:
Most common site of infection for females
Endocervical canal
Chlamydia:
Other sites of infection for males
- rectum, eye, oropharynx
Chlamydia: other site(s) of infection for females
- urethra, eye, rectum, oropharynx
Chlamydia:
Symptoms in males
- Asymptomatic: more than 50% of urethral and rectal
- Urethral infection: mild dysuria, discharge
- Pharyngeal infection: mild pharyngitis
Chlamydia:
Symptoms for females
- Asymptomatic for more than 66% of endocervical infection
- urethral infection: dysuria and urinary frequency uncommon
- pharyngeal infection: same as for males
Chlamydia:
Signs in Males
- scant to profuse, mucoid to purulent urethral or rectal discharge
- rectal: pain, discharge, bleeding
Chlamydia:
Signs in Females
- abnormal vaginal discharge
- uterine bleeding
- scant to profuse purulent or urethral or rectal discharge
Chlamydia complications in males
- epididymitis
- reactive arthritis
Chlamydia complications in females
- pelvic inflammatory disease
- reactive arthritis
Chlamydia infection during pregnancy
- may be transferred to an infant who comes in contact with cervicovaginal secretions
= 2/3 acquire infection after contact - may manifest in eyes, nasopharynx, rectum, or vagina:
= conjunctivitis - develops in ~50%
= pneumonia - develops in ~16%
Chlamydia: Diagnosis
- NAATs
- Culture
- Screening
NAATs (Chlamydia)
- most sensitive and most recommended for: women and men
- women: endocervix or vaginal swabs or urine
- men: urethral swab or urine
- can also obtain rectal or pharyngeal specimens
- may use self-collected specimens (urine, vaginal, rectal, or pharyngeal
- POC also available
Culture (Chlamydia)
uncommon use
Chlamydia screening
Recommended for:
- sexually active women <25 years of age
- men and women at risk
Syphilis is caused by?
- a spirochete
- Treponema pallidum
Syphilis MOA
- typically spread by sexual contact with infected mucus membranes or skin lesions
- T.pallidum penetrates intact mucus membrane or break in epithelium
- spirochetes enter blood
4 stages of syphilis
1) Primary Syphilis
2) Secondary Syphilis
3) Latent Syphilis
4) Tertiary Syphilis
Other: Neurosyphilis, Ocular Syphilis, and Otosyphilis
Primary syphilis
- Chancre develops at site of exposure
- Common locations of chancre:
= external genitalia, perianal region, mouth, throat - usually painless
- Lymphadenopathy may also occur
- ## highly contagious
Which stage is syphilis the most contagious?
- primary syphilis
How long does chancre usually heals for?
- within 1 to 8 weeks
Secondary syphilis
- occurs after initial infection if untreated or inadequately treated
- Multisystem involvement:
= rash, mucocutaneous eruptions, lymphadenopathy, malaise, headache, arthralgia, fever, sore throat, stomatitis, nausea, loss of appetite, inflamed eyes, alopecia, condylomata lata
Latent Syphilis
- positive serologic test + no evidence of disease
- asymptomatic
- Early latent
- Late latent
Early Latent Syphilis
- aka syphilis, early non-primary non-secondary
- initial infection occurred within the previous 12 months
Late latent Syphilis
- aka syphilis of unknown duration
- aka syphilis, unknown duration or late
- initial infection occurred more than 12 months ago or insufficient evidence that infection was acquired during the previous 12 months
Tertiary Syphilis
- aka late clinical manifestations
- Gumma
- Cardiovascular: aortitis or aortic insufficiency
Gumma
- occurs in tertiary syphilis
- rubbery, necrotic, destructive lesions
- can infiltrate any organ or tissue
- most common in skin, bone, soft tissue, and liver
Syphilis with Neurologic Manifestation or Neurosyphilis
- may occur at any stage of syphilis
- stage reported as “ with neurologic manifestations”
- T.pallidum invades the CNS
- CSF abnormalities consistent with CNS infection
- meningitis, general paresis, dementia, tabes dorsalis, deafness, blindness, ataxia, sensory loss
Ocular Syphilis and Otosyphlis
- can occur at any stage of syphilis
- commonly presents in early stages with or without CNS involvement
- Ocular syphilis: may result in permanent vision loss
- Otosyphilis: may result in permanent hearing loss
Congenital Syphilis
- T.pallidum can cross the placenta anytime during pregnancy
- may result in: death, prematurity
- symptoms may be seen in: 1st months of life, later in childhood or adolescence
Syphilis diagnosis
- microscopic examination
- serologic testing: nontreponemal, treponemal
Microscopic examination (Syphilis)
- specimens collected from lesions or enlarged lymph nodes
- Identifies: T.pallidum spirochete, Antibodies to T.pallidum
Nontreponemal Tests and Traditional Algorithm
- venereal disease research laboratory test (VDRL)
- rapid plasma reagin test (RPR)
- positive = presence of any stage of syphilis or congenital syphilis
- may see false positives/negatives
- reported quantitatively: decline with treatment and may become nonreactive
- traditionally used for screening
- used for following progression of disease, recovery after therapy, and reinfectioin
Treponemal Tests and Reverse Sequence Algorithm
- more sensitive
- used for confirming diagnosis
- not used for following treatment
- remain reactive for life in most patients
Herpes Simplex Virus
Types:
- Genital Herpes
- Neonatal Herpes
Genital Herpes
- caused by HSV
- transmitted when infection secretions come in contact with mucosal surfaces through:
= urethra, oropharynx, cervix, conjunctivae, abraded skin
Type 1 Genital Herpes
- usually associated with oropharyngeal disease
- “cold sores”
Type 2 Genital Herpes
- usually associated with genital disease
Genital Herpes MOA
- virus replicates in skin and mucus membranes at site of infection
5 stages of Genital Herpes
1) Primary mucocutaneous infection
2) infection of the ganglia
3) establishment of latency
4) reactivation
5) recurrent infection
Genital Herpes:
Incubation Period?
2-14 days
Primary- 1st episode (Genital Herpes)
- initial genital infection
- seronegative for antibodies to HSV-1 or 2
- eruption of multiple pustular ulcerative lesions on external genitalia
- itching, pain in the genital area, fever, headache, malaise, vaginal or urethral discharge, tender inguinal adenopathy, urine retention, parasthesias
- viral shedding
Non-primary-1st episode (Genital Herpes)
- initial genital infection
- clinical or serologic evidence of prior HSV (usually HSV-1)
Recurrent (Genital Herpes)
- 2nd or subsequent outbreaks
Development of eruption of multiple pustular ulcerative lesions on external genitalia
- develop over 7-10 days
- heal within 2-4 weeks
viral shedding in genital herpes
- Primary: ~11-12 days
- Non-primary: ~7 days
Genital Herpes Symptoms – Recurrent
- Prodrome
- fewer lesions
- shorter duration (heal within 7 days)
- milder symptoms
- viral shedding: ~4 days
Asymptomatic viral shedding
- can occur during 1st episode or recurrent episodes
Genital Herpes complications
- lesions at extragenital sites: eye, rectum, pharynx, fingers
- CNS involvement
Neonatal herpes
- high morbidity and mortality: Fatality rate of 50%
- may lead to permanent neurologic damage
How is neonatal herpes typically transmitted?
- via exposure to HSV in the birth canal
Which stage is Neonatal Herpes the greatest risk?
- during 1st episode of primary infections
Genital Herpes Diagnosis
- Type-specific virologic tests
- Type-specific serologic tests
Type-specific virologic test (Genital Herpes)
- if genital lesions present:
-> Culture or NAAT - NAAT is the most sensitive
Type-specific serologic tests
- if genital lesions are not present
Trichomoniasis
- caused by Trichomonas vaginalis
- flagellated, motile protozoan
- more common in females than males
Trichomonads MOA
- attach to vaginal or urethral mucosa
- elicit an inflammatory response
- manifests as discharge containing large numbers of PMN leukocytes
Trichomoniasis Incubation period
- 3-28 days
- the same for males and females
Trichomoniasis:
Most common site of infection
- Urethra: males
- Endocervical canal: females
Trichomoniasis:
Other Sites of Infection
- Males: Rectum, eye, oropharynx
- Females: Urethra, eye, rectum, oropharynx
Trichomoniasis symptoms in males
- asymptomatic or minimally symptomatic
- clear to purulent urethral discharge, dysuria, pruritus
Trichomoniasis symptoms in females
- asymptomatic or minimally symptomatic
- scant to copious, malodorous, yellow-green vaginal discharge, pruritus, dysuria, dysparenunia
Trichomoniasis signs in males
- urethral discharge
Trichomoniasis signs in females
- vaginal discharge
- vaginal pH = 4.5-6
- inflammatory/erythema of vulva, vagina, and/or cervix, urethritis
Trichomoniasis Complication in males
- epididymitis and chronic prostatitis
- infertility
Trichomoniasis Complication in females
- pelvic inflammatory disease
- premature labor, premature rupture of membranes, low birth weight infants
- cervical neoplasia
Trichomoniasis Diagnosis
- vaginal discharge pH
- wet-mount microscopic examination of vaginal discharge
- cultures
- NAATs and antigen detection tests
Vaginal discharge pH (Trichomoniasis)
- T. vaginalis requires pH range = 4.9 to 7.5 for survival
- pH >5 vaginal discharge = presence of T.vaginalis or Gardnerella vaginallis
Wet-mount microscopic experiments of vaginal discharge (Trichomoniasis)
- confirmed if presence of pear-shaped, flagellating organisms
- inexpensive; can be performed in clinic
Cultures (Trichomoniasis)
- highly specific and sensitive; but not as sensitive as NAATs
- may use for confirming diagnosis
NAATs and antigen detection tests (Trichomoniasis)
- highly sensitive and specific
- preferred testing method
- POC available for women with vaginal or urine specimens
