For a presumptive diagnosis of gonorrhea, which criteria must be present from an exudate?

The presence of typical gram-negative, intracellular diplococci in a smear of urethral exudate serves as a key criterion for the presumptive diagnosis of gonorrhea. This particular finding is characteristic of Neisseria gonorrhoeae, the bacterium responsible for the infection. When examining an exudate, the detection of these intracellular diplococci within polymorphonuclear leukocytes (PMNs) indicates an active infection, as this reflects the bacteria's typical morphology and cellular behavior.

In contrast, while gram-negative diplococci might appear in vaginal or rectal samples, the most definitive criterion comes from urethral exudates, especially in males, where the presentation is more distinct and clinically relevant. Therefore, this specific finding strongly supports a diagnosis of gonorrhea and correlates with the common clinical practices for diagnosing this sexually transmitted infection.

Growth on MacConkey agar, which is selective for gram-negative bacteria, does not specifically indicate the presence of N. gonorrhoeae, as this organism does not grow well on that medium. Thus, the most reliable and recognized evidence leading to a presumptive diagnosis comes from examining the smear of urethral exudate.