VAGINITIS
Vaginitis is a vaginal infection. They cause vaginal discharge that you inspect under a microscope after adding KOH (wet mount).
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BACTERIAL VAGINOSIS (BV) is an imbalance of normal vaginal flora, specifically involving more Gardnerella vaginalis and less lactobacilli. G. vaginalis is an anaerobe that’s neither gram positive or negative. Instead of doing a gram stain, you can do a wet prep of the vagina, and see the pesky bacteria studding the outside of epithelial cells (clue cells). Its discharge is thin, gray and smells fishy. Adding KOH amplifies the fishy smell, which is called the whiff test. Since it’s an anaerobe, you can treat BV with Metronidazole. There are two main causes. (1) Douching drowns the aerobic lactobacili but spares the anaerobic G. vaginalis. (2) Sex can transmit G. vaginalis from penises. That’s right, penises have their own flora, especially uncircumsized ones. Lactobacilli secrete acid. Without them, the vaginal pH becomes more basic (over 4.5).
CANDIDAL VULVOVAGINITIS is a yeast infection. It’s due to our friend Candida albicans, the yeast with pseudohyphae. It produces thick white “cottage cheese” like discharge, and also creates some vaginal erythema. When you throw KOH onto a wet prep, you’ll see the classic pseudohyphae. Unlike with the other two, the vaginal pH retains its normal acidity (pH 4 to 4.5). Treat with Fluconazole. The most common cause is antibiotics, which kills off the normal vaginal flora but leaves the fungal flora untouched.
TRICHOMONAS VAGINITIS (“trich”) is a protozoan STI. It exclusively lives in our genitals. It’s also diagnosed with a wet mount, looking for motile trichomonads (fat lil blobs with little antennae). Since it's a protozoan, treat it with Metronidazole. In men, it’s usually asymptomatic, but can cause some penile discharge. In women half of infections are symptomatic. It produces itching, yellow-green foul-smelling frothy discharge and a strawberry cervix (cervical redness).
GONORRHEA
Neisseria gonorrhoeae
Gonorrhea is an STI that initially infects the urethra. It’s capable of clinging to the urethra because it has pili. It can fight off the IgA that flood the urine because it produces IgA protease. And it can fight off antibodies because its pili are constantly rearranging their shape (antigenic variation) -- this means that humans can’t establish long term immunity or a vaccine, making reinfection commonplace. After a few days, it can dig past the uroepithelium and into the tissue. There it will be eaten by a neutrophil, where it will live (facultative intracellular). It can survive the oxidative burst because it has catalase. It’s Gram negative, so treat it with Ceftriaxone. It’s nowadays diagnosed with a PCR / nucleic acid amplification test (NAAT), but the old-school way to identify it is to look for intracellular Gram negative diplococci under the microscope.
Gonorrhea is famous for being an STI. But it can also cause a few unexpected conditions.
Asymptomatic infections are common. Gonorrhea can occasionally decide to not express its antigenic proteins, allowing it to hide from the immune system. This prevents infected individuals from realizing they have an STD, enabling its spread.
Urethritis, which causes painless pus-like urethral discharge. Even though it’s an infection, gonorrhea is usually afebrile.
In men, it can spread to the testes (epididymitis or orchitis).
In women, it can spread up to the uterus and cause pelvic inflammatory disease (PID). PID is a big deal. It causes fever, pelvic pain and dyspareunia. Suspect PID if the patient has cervical motion tenderness. PID is notable for causing fallopian fibrosis, which is a major cause of infertility and ectopic pregnancies.
Septic Arthritis, which is a bacterial infection within a joint. It spreads there hematogenously. Any time a young sexually active person gets a swollen / red / painful joint (knee), you should suspect gonorrhea or chlamydia. But to distinguish the two, you should aspirate some of the joint fluid. If it’s full of intracellular bacteria, then it’s gonorrhea. If it’s seemingly sterile, then it’s chlamydia (chlamydia is good at hiding).
Fitz-Hugh-Curtis Syndrome, which is inflammation of Glisson’s capsule - the sack that encases the liver -- which leads to RUQ pain. Inflammation of this capsule leads to fibrosis and scarring, which causes the capsule to adhere to its neighbor, the peritoneum. The buzz-word here is “violin string” adhesions connecting the liver to the peritoneum. Since the capsule sits adjacent to the diaphragm, the pain gets worse with deep breaths (pleuritic).
Disseminated Gonococcal Infection refers to a gonorrhea infection that spreads throughout the entire body. The classic triad is joint pain, pustular skin lesions and tendon inflammation (tenosynovitis).
Neonatal Conjunctivitis, which occurs 2 to 3 days after a vaginal delivery. If mom has an active case of Gonorrhea, and she delivers a baby through her infected birth canal, the child can become inoculated with gonorrhea. It loves to infect the conjunctiva of newborns, although it takes several days for symptoms to become apparent. Gonorrhea causes conjunctival erythema and greenish pus-like ocular discharge. Left untreated, it can permanently impair vision. Chlamydia can also cause conjunctivitis in newborns, but chlamydia usually takes at least a week to begin, and its discharge is more watery. In areas with high rates of STIs, all babies receive prophylactic erythromycin eye ointment rubbed into their eyes after birth.
Note 1 - Gonorrhea and Chlamydia are commonly spread together. So treat both! Give Ceftriaxone AND Azithromycin, unless you’ve ruled it out with a NAAT test.
Note 2 - there is one other pathogenic Neisseria species -- Neisserria meningitidis -- which causes severe meningitis (with petechiae).
Facultative intracellular gram negative diplococci
CHLAMYDIA
Chlamydia Trachomatis
Chlamydia is the other bacterial STI that infects urethras. Chlamydia is a weird little bacteria. It can’t make ATP, meaning it has to live inside of eukaryotic cells (obligate intracellular) and steal their ATP. It’s really small, since it doesn’t have to worry about making its own ATP. Since it predominantly lives inside other cells, it has developed an unusual cell wall that lacks muramic acid (and by extension, no Peptidoglycan). Without Peptidoglycan, we can’t kill Chlamydia with beta-lactam antibiotics. Use something that inhibits protein synthesis instead, such as Azithromycin or Doxycycline. The unusual cell wall also means that gram stains don’t work properly, and pathologists have to use Giemsa stains instead (the intracellular organism test).
Obligate intracellular bacteria have a hard time surviving outside of cells, which can make it tough to infect other cells. Chlamydia has gotten around this problem by evolving a durable cyst-like form -- the elementary body. Elementary bodies are found in the urethral discharge of infected individuals. But once inside a eukaryotic cell, the elementary body can transform into the “regular” form -- the reticulate body. The reticulate body is capable of replicating. Once it has replicated as much as it can, all of the Reticulate bodies switch to Elementary bodies, and then explode out of that host cell. Like gonorrhea, chlamydia can cause a lot of different problems. Most of these are caused by subtypes D - K. Yes, there are at least a dozen different chlamydia subtypes.
Asymptomatic infections, which are the most common presentation.
Urethritis, which causes pus-like urethral discharge. It’s quite similar to gonorrhea in this instance, and may also cause PID or testicular infection.
Reactive Arthritis, which is very different from the septic arthritis caused by gonorrhea. Instead of being a literal infection of a joint, chlamydia tricks the body into attacking its own joints -- it’s an autoimmune arthritis. It’s also called Reiter’s Syndrome. The classic triad is urethritis, arthritis and conjunctivitis. “Can’t see, can’t pee, can’t climb a tree.” Treat it with NSAIDs.
Neonates can get two infections from Chlamydia
Conjunctivitis, that starts a week after delivery, and produces watery discharge.
Pneumonia, which starts 1 to 2 months after birth. It causes an unusual coughing pattern - the staccato cough (single cough, inhale, single cough, inhale, single cough, etc.).
Lymphogranuloma Venereum is an STI caused by a different chlamydia serotype (L1, L2, L3) than urethritis (D - K). LV causes a single genital ulcer at the site of infection, which eventually fades away as the infection spreads to the nearby lymph nodes (inguinal / femoral) causing big painful red lymphadenopathy (buboes) that can rupture and drain pus. Treat with antibiotics and drainage.
Trachoma is an eye disease caused by a different serotype (A, B, C). These strains are more common in Africa. They cause acute conjunctivitis, followed by blindness.
Note - there are 2 other Chlamydia species. Chlamydia pneumoniae is a cause of atypical pneumonia. Chlamydia psittaci is the cause of “parrot fever.”
GENITAL LESIONS
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