(10) Bacillus anthracis.
(12) Most strains of enterococci.
b. Usual Dosage. Adult--250 to 500 mg, 4 times daily orally, or 250 to 500 mg,
every 6 hours IM or IV.
c. Cautions and Warnings: Adverse Reactions. The cautions and warnings
for ampicillin, as well as possible adverse reactions, are the same as with penicillin V.
d. Supply. Ampicillin is supplied as 250-mg and 500-mg capsules and as a
flavored dry mix for oral suspension (3.75 gm to be reconstituted to 150 ml of 125 mg/5
ml suspension, 5 gm to be reconstituted to 100 ml of 250 mg/5 ml suspension, 7.5 gm
to be reconstituted to 150 ml of 250 mg/5 ml suspension).
5-19. PENICILLINS RESISTANT TO PENICILLINASE
The following semisynthetic penicillins, which are resistant to penicillinase,
should be used only to treat infections caused by strains of bacteria, particularly
staphylococci, which have developed a resistance to penicillin. This limited use helps
discourage the further development of strains resistant to these drugs also. The
precautions and contraindications for these drugs are similar to those for the other
a. Sodium Methicillin (Staphcillin). Methicillin is given IM or IV.
b. Sodium Oxacillin (Prostaphlin). Sodium oxacillin may be given orally 1 or 2
hours before meals. Since absorption by the oral route is unreliable, it should not be
used for the most serious infections. Preparations for IM or IV administration are also
c. Sodium Dicloxacillin (Dynapen). Sodium dicloxacillin should be given orally
1-2 hours before meals. May be used to initiate therapy in any client in whom a
staphylococcal infection is suspected.
d. Sodium Nafcillin (Unipen). Serum levels of nafcillin after oral administration
are low and unpredictable. Use parenteral therapy initially in severe infections and
change to oral therapy as the condition warrants.
The cephalosporins are a family of antibiotics resembling the penicillins. They
are bactericidal agents, active against both gram-positive and gram-negative bacteria.
The cephaloporins resist the action of penicillinase. They are divided into first, second,