Final answer:
Narrow spectrum penicillinase sensitive penicillins are a class of antibiotics mostly effective against gram-positive bacteria and are susceptible to degradation by penicillinase. Penicillin G, although the first widely used, is not acid stable and thus not orally administered, leading to the use of other oral forms like penicillin V, ampicillin, and amoxicillin.
Step-by-step explanation:
Narrow spectrum penicillinase sensitive penicillins are a type of antibiotics effective against a limited range of bacteria, mainly gram-positive ones, and susceptible to degradation by the enzyme penicillinase. These drugs include penicillin G, which was the first widely used penicillin but is unstable in the acidic environment of the stomach and thus, cannot be administered orally.
Instead, penicillin V, ampicillin, and amoxicillin are preferred for oral use as they are acid stable. Additionally, to address bacterial resistance due to penicillinase, chemists have developed penicillin analogs such as methicillin, which are not inactivated by this enzyme.
Bacteria that produce β-lactamases, which includes penicillinase, can inactivate many β-lactam antimicrobials by cleaving the β-lactam ring, a key structural component of these drugs. Thus, extended-spectrum β-lactamase-producing pathogens show resistance to a wide array of β-lactams.
To combat these resistant strains, penicillin analogs resistant to β-lactamase degradation have been crucial. However, it's important to note that β-lactamases do not affect antibiotics such as vancomycin and that echinocandins are a different class targeting fungal cell walls, unrelated to β-lactam antibiotics.