Final answer:
Ampicillin is the first-line penicillin for gram-negative coverage.
Step-by-step explanation:
The first-line penicillin for gram-negative coverage is ampicillin. Ampicillin is effective against certain gram-negative bacteria, including Escherichia coli (E. coli). It is commonly used in the treatment of urinary tract infections, respiratory tract infections, and intra-abdominal infections caused by gram-negative bacteria. Penicillins are a class of antibiotics that are generally more effective against gram-positive bacteria but have limited activity against most gram-negative bacteria. However, certain penicillins have extended coverage that includes some gram-negative organisms. Ampicillin and amoxicillin are examples of penicillin that have activity against certain gram-negative bacteria.