3.12 Neisseria Species

Microbiology review for the USMLE Step 1 exam

• Neisseria species are gram negative diplococci that infect and live inside neutrophils
• Two main species that cause infections in humans: Neisseria gonorrhoeae and Neisseria meningitidis
• Neisseria gonorrhoeae causes the sexually transmitted infection gonorrhea, which is the second most common STI
• Risk factor for gonorrhea is unprotected sex with an infected person
• N. gonorrhoeae uses pilli to adhere to epithelial cells and invade, causing a local skin infection at the site of inoculation
• Females: cervix is the most common site of infection, causes cervicitis, symptoms include thick yellow or green vaginal discharge, dysuria, and pelvic pain. If left untreated, it can cause PID, ectopic pregnancy, infertility, and chronic pelvic pain
• Males: urethra is the most common site of infection, symptoms include yellow-green discharge, dysuria, and painful swollen testes (less common)
• If left untreated, it can infect more proximal structures and cause prostatitis
• Diagnosis is done by swabbing the urethra or cervix and sending it for nucleic acid amplification testing
• Can also cause septic arthritis (in contrast, Chlamydia causes reactive arthritis)
• "Gonorrhea gon go to the joints"
• Treatment typically involves a cephalosporin (like ceftriaxone) and azithromycin to also cover chlamydial infection
• Conjunctival gonorrhea can occur in newborns during the birthing process, causing conjunctivitis in the eye.