Streptococcal or Staphylococcal cellulitis: This is the most common cause of cellulitis, especially given the history of a cut from an outdoor water slide, which could easily become contaminated with bacteria. Streptococci and Staphylococci are common skin flora that can cause infection when the skin barrier is compromised.

Pseudomonas aeruginosa infection: Given the exposure to water, particularly from an outdoor water slide, there's a possibility of infection with Pseudomonas aeruginosa, which is known to thrive in moist environments.
Aeromonas hydrophila infection: This bacterium is found in fresh or brackish water and can cause skin infections, especially after exposure to contaminated water.

Necrotizing fasciitis: Although less common, this is a severe and potentially life-threatening condition that requires immediate attention. It can be caused by Streptococci, Staphylococci, or a combination of bacteria.
Gas gangrene (Clostridial myonecrosis): This rare but deadly infection can occur if the wound is contaminated with dirt or foreign material, leading to infection with Clostridium perfringens.
Erysipelas: A type of cellulitis that involves the upper dermis, typically caused by Streptococci, and can be more severe and require specific treatment.

Vibrio vulnificus infection: This bacterium is found in seawater and can cause severe skin infections in individuals exposed to contaminated water, especially those with open wounds.
Mycobacterial infections: Certain Mycobacteria, like Mycobacterium marinum, can cause skin infections after exposure to contaminated water, though this is less common.
Fungal infections: Though rare, fungal infections such as those caused by Blastomyces or Histoplasma could occur, especially in immunocompromised individuals or after specific exposures.