How Do Penicillinase-Resistant Penicillins Work?

Penicillinase-resistant penicillins (also referred to as second-generation penicillins) are antibiotics that are resistant to the bacterial enzyme beta-lactamase and are used to treat staphylococcal and streptococcal bacterial infections.

Penicillinase-resistant penicillins are semisynthetic modifications of natural penicillins and their basic structure includes a thiazolidine ring connected to a beta-lactam ring. Bacterial resistance to penicillins is mediated by beta-lactamase, an enzyme that destroys the beta-lactam ring of penicillin, making it ineffective. Penicillinase-resistant penicillins resist this hydrolysis of the beta-lactam ring by the bacterial enzyme.

Penicillinase-resistant penicillins work by inhibiting bacterial cell wall synthesis (cell walls are necessary to protect the bacteria from their environment and keep the contents of the cell together) by attacking the peptidoglycans (the mesh-like structure that increases the strength of the cell wall), leading to the bursting of the bacteria and eventually its death.

Conditions treated with penicillinase-resistant penicillins include the following:

• Pneumonia
• Sepsis (life-threatening illness caused by your body’s response to an infection)
• Meningitis (inflammation of the membranes lining the brain and spinal cord)
• Endocarditis (inflammation of the heart’s inner lining called the endometrium)
• Uncomplicated gonorrhea (a sexually transmitted disease affecting both men and women)
• Syphilis (a bacterial infection spread by sexual contact)
• Otitis media (painful ear infection)
• Bone and joint infections
• Osteomyelitis (infection in a bone)
• As prophylaxis in high-risk patients undergoing surgery (prosthetic valve or congenital heart anomaly)
• Intra-abdominal infections
• Pharyngitis (inflammation of the back of the throat)
• Sinusitis (inflammation of the sinus around the nose)
• Skin infections
• Urinary tract infection
• Acute pyelonephritis (bacterial infection of the kidney)
• Typhoid fever
• Methicillin-resistant Staphylococcus aureus infection

Common side effects include:

• Diarrhea
• Nausea
• Headache
• Skin rash/hives (itchy, red bumps on the skin)
• Vomiting
• Pain and redness at the site of injection
• Swelling
• Abdominal pain
• Hypersensitivity

Other rare side effects include:

• Shortness of breath
• Joint pain
• Sudden lightheadedness and fainting
• Puffiness and redness of the face
• Scaly, red skin
• Sore mouth and tongue, sometimes with white patches
• Anxiety, fear, or confusion
• Hallucinations (involve hearing, seeing, feeling, and smelling things that are not real)
• Unusual bleeding
• Seizures (sudden uncontrolled electrical disturbance in the brain)
• Liver toxicity
• Anaphylaxis (severe allergic reactions)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Drug names include:                               

• Bactocill
• Dicloxacillin
• Nafcil
• Nafcillin
• Nallpen
• Oxacillin