"Bacterial vaginosis is caused by an imbalance in the vaginal microbiota, with a decrease in lactobacilli and an increase in vaginal pH. G. vaginalis is the most common cause of bacterial vaginosis, which is associated with vaginal discharge, odor, burning, and itching. Gonorrhea is caused by N. gonorrhoeae, which can cause infection of the reproductive and urinary tracts and is associated with symptoms of urethritis. If left untreated, it can progress to epididymitis, salpingitis, and pelvic inflammatory disease and may enter the bloodstream, leading to infections in other sites of the body. Chlamydia is the most commonly reported STI and is caused by C. trachomatis. Most infections are asymptomatic, and infections that are not treated can spread to involve the epididymis of men and cause salpingitis and pelvic inflammatory disease in women. Syphilis is caused by T. pallidum and has three stages: primary, secondary, and tertiary. Primary syphilis is associated with a painless hard chancre lesion on the genitalia. Secondary syphilis is associated with skin and mucous membrane lesions. Tertiary syphilis is the most serious and life-threatening and can involve serious nervous system damage. Chancroid is an infection of the reproductive tract caused by H. ducreyi that results in the development of characteristic soft chancres. Bacterial vaginosis is associated with Gardnerella vaginalis, Bacteroides species, Fusobacterium species, and other organisms. It is often asymptomatic but may cause vaginal discharge, burning, odor, or itching. It is an opportunistic infection caused by an imbalance of the normal vaginal microbiota. Diagnosis can be made using a vaginal smear. Antimicrobial drugs include clindamycin, metronidazole, and tinidazole."