Which antibiotics can be combined with aztreonam for GI tract infections?

Aztreonam is a monocyclic beta-lactam antibiotic that is primarily effective against Gram-negative bacteria and has no activity against Gram-positive bacteria or anaerobes. Therefore, when treating gastrointestinal (GI) tract infections, particularly those that may involve anaerobic organisms or Gram-positive organisms, it is beneficial to combine aztreonam with other antibiotics that can extend the spectrum of coverage.

The option that includes clindamycin, which is effective against anaerobes and some Gram-positive bacteria, combined with a fluoroquinolone, which provides coverage for Gram-negative aerobes, presents a synergistic approach to treating GI infections. This combination ensures that both anaerobic and aerobic Gram-negative bacteria are adequately covered, addressing the polymicrobial nature of many GI infections.

Other options, while having individual merits, do not offer the same broad coverage. Metronidazole effectively targets anaerobic organisms but doesn’t cover the same spectrum as clindamycin plus fluoroquinolone. Gentamicin is an aminoglycoside that primarily targets aerobic Gram-negative bacteria but doesn't provide coverage against anaerobes. Ampicillin is a broader-spectrum penicillin that covers some anaerobic bacteria but may not be the best choice in the context of Gram-negative coverage in