Antimicrobial Pharmacology: Antibacterials, Antivirals, Antifungals, Antiparasitics, and Tuberculosis

Comprehensive vocabulary flashcards covering pharmacology, mechanism of action, clinical indications, adverse effects, black box warnings, and nursing implications for antiviral, antifungal, antiparasitic, antibacterial, and antitubercular medications.

Acyclovir (Zovirax)

A herpesvirus prototype agent that interrupts viral DNA replication to decrease genital herpes and herpes simplex virus (HSV) pain and duration. Nursing implications include applying topical formulations with a gloved hand and monitoring for encephalopathy with IV administration.

Ganciclovir (Cytovene)

A prototype antiviral that inhibits viral DNA synthesis, used to treat cytomegalovirus (CMV). It carries two black box warnings (BBWs): severe bone marrow toxicity (granulocytopenia/neutropenia and thrombocytopenia) and the requirement to maintain contraceptive precautions during and for $90\,\text{days}$ after treatment due to birth defects.

Valganciclovir (Valcyte)

The oral formulation of ganciclovir with the same black box warnings (granulocytopenia, thrombocytopenia, and contraceptive precautions). It should be administered with a high-fat meal to increase drug absorption.

Ribavirin (Virazole)

An antiviral prototype that interferes with DNA and RNA replication, administered via inhalation to treat respiratory syncytial virus (RSV) in children. It carries a black box warning for severe teratogenic effects, and nurses must monitor for respiratory distress such as nasal flaring.

Oseltamivir phosphate (Tamiflu)

An influenza prototype drug that inhibits newly formed viruses from escaping the host cell. Indicated for treatment and prophylaxis in patients at least $1\,\text{year}$ old; taking it with food reduces gastrointestinal upset such as nausea, vomiting, and diarrhea.

Lamivudine (Epivir)

A hepatitis prototype that incorporates into viral DNA to terminate replication, indicated for chronic Hepatitis B and off-label for HIV. Adverse risks include pancreatitis, alongside black box warnings for lactic acidosis (often presenting as musculoskeletal pain) and hepatomegaly with steatosis.

Zidovudine (AZT, Retrovir)

A prototype nucleoside reverse transcriptase inhibitor (NRTI) that terminates viral DNA synthesis. Used clinically to prevent maternal-fetal HIV transmission; carries black box warnings for granulocytopenia/pancytopenia and lactic acidosis with hepatomegaly.

Efavirenz (Sustiva)

A prototype nonnucleoside reverse transcriptase inhibitor (NNRTI) that prevents HIV transcription and works synergistically with NRTIs. It is contraindicated in hepatic impairment and can cause Stevens-Johnson syndrome and central nervous system effects (countered by taking at bedtime).

Pre-Exposure Prophylaxis (PrEP)

A preventive daily regimen using Truvada (tenofovir and emtricitabine) for HIV-negative individuals at high risk. Daily adherence lowers the risk of HIV transmission by approximately $99\%$ from sexual activity and approximately $74\%$ from injection drug use.

Amphotericin B deoxycholate (Fungizone)

A polyene antifungal prototype that disrupts cell membrane integrity to stop reproduction, reserved via black box warning for potentially fatal systemic fungal infections. Known as 'ampho-terrible' due to common renal impairment, organ failure, and cardiac/respiratory arrest; requires pre-medication, IV sodium chloride hydration, a separate IV line, and an in-line filter.

Lipid Formulation of Amphotericin B (Abelcet, AmBisome)

An advanced formulation of amphotericin B packaged inside a phospholipid bilayer liposome designed to significantly reduce nephrotoxicity. Unlike the deoxycholate formulation, an in-line filter must NOT be used during administration.

Fluconazole (Diflucan)

An azole antifungal prototype that alters membrane permeability, serving as the drug of choice for Candida infections. The dose must be halved in poor renal function; it carries a risk of hepatotoxicity and acts as a CYP450 enzyme inhibitor that elevates serum levels of drugs like phenytoin and warfarin.

Flucytosine (Ancobon)

A pyrimidine analog antifungal that causes cell death, used as an adjunct alongside amphotericin B for Candida and Cryptococcus infections. Carries a black box warning for renal impairment, causes hepatotoxicity and bone marrow toxicity, and requires close lab monitoring for dose adjustments.

Oral Candidiasis (Thrush)

A fungal infection of the mouth and tongue caused by Candida albicans, presenting as white curd-like plaques on oral mucous membranes and occurring most commonly in immunocompromised patients.

Metronidazole (Flagyl)

An amebicide and antibacterial that diffuses across microbial membranes to disrupt DNA, indicated for intestinal amebiasis, trichomoniasis, and Clostridium difficile. Carries a black box warning for carcinogenicity in rats; patients must avoid alcohol during therapy and for $3\,\text{days}$ afterward to avoid a disulfiram-like reaction.

Chloroquine phosphate (Aralen)

An antimalarial prototype that interferes with parasite DNA, RNA, and metabolic function, indicated for malaria prophylaxis and treatment. Associated with visual disturbances and electrocardiogram changes; dosed once weekly on the same day for prophylaxis, and daily for acute treatment.

Mebendazole (Enverm)

An anthelmintic prototype that blocks glucose uptake in parasitic helminths (such as pinworms, hookworms, roundworms, and whipworms). Tablets must be chewed or crushed before swallowing; the medication is teratogenic.

Enterobius vermicularis

The pinworm; a contagious parasitic nematode that causes intense perianal itching. Management includes strict hand hygiene, daily washing of clothes and bed linens, disinfecting toilets, and treating all family members simultaneously.

Permethrin (Elimite, Nix)

A topical scabicide and pediculicide that blocks sodium influx, paralyzing and killing parasites. For lice: wash hair, apply cream for $10\,\text{minutes}$, rinse, and comb out nits (repeat in $1\,\text{week}$ overnight if needed); for scabies: apply head-to-toe and leave on for $8\text{--}14\,\text{hours}$.

Beta-Lactam Ring

A core four-membered cyclic amide chemical structure shared by penicillins, cephalosporins, carbapenems, and monobactams that inhibits bacterial cell wall synthesis but makes these antibiotics susceptible to enzymatic destruction by bacterial beta-lactamases.

Ampicillin (Principen)

A prototype penicillin antibiotic that inhibits bacterial cell wall synthesis, active against strong gram-positive and weak gram-negative organisms. Nursing implications include watching for hypersensitivity reactions and avoiding direct mixture with aminoglycosides, which it inactivates.

Piperacillin / Tazobactam (Zosyn)

A combination antibiotic pairing an extended-spectrum penicillin with a beta-lactamase inhibitor to expand antimicrobial activity against both strong gram-positive and gram-negative pathogens.

Cefazolin (Ancef, Kefzol)

A first-generation cephalosporin prototype that inhibits bacterial cell wall synthesis, predominantly used for surgical prophylaxis against strong gram-positive pathogens. Nursing protocol requires administration exactly $60\,\text{minutes}$ prior to the initial surgical incision.

Ceftriaxone (Rocephin)

A third-generation cephalosporin active against both gram-positive and gram-negative bacteria. Deep IM injections are painful and should be reconstituted with $1\%$ lidocaine; it is unique among beta-lactams because it does not require renal dose adjustments.

Imipenem-cilastatin (Primaxin)

A broad-spectrum carbapenem prototype that inhibits bacterial cell wall synthesis, covering pathogens including Pseudomonas aeruginosa. Reserved specifically for critical illness; carries a notable adverse risk of precipitating seizures in patients with preexisting seizure disorders.

Aztreonam (Azactam)

A monobactam prototype that inhibits cell wall synthesis, possessing strong gram-negative activity while completely lacking gram-positive coverage. It exhibits limited cross-allergenicity, making it safe for patients with severe penicillin allergies, and is saved for critical illness.

Beta-Lactam Cross-Allergenicity

The clinical principle evaluating shared allergic reactivity between beta-lactam classes. While cross-reactivity between penicillins and cephalosporins/carbapenems occurs in less than $1\%$ of patients, monobactams (aztreonam) show virtually no cross-reactivity and are considered safe in penicillin allergy.

Gentamicin (Garamycin)

An aminoglycoside prototype that destroys bacterial ribosomes to treat severe gram-negative infections. Carries black box warnings for nephrotoxicity and ototoxicity; administered via conventional multi-dose or extended-interval once-daily schedules and requires peak and trough level monitoring.

Ciprofloxacin (Cipro)

A fluoroquinolone prototype that interferes with bacterial DNA synthesis, serving as first-line therapy for Bacillus anthracis (anthrax). Carries black box warnings for tendonitis/tendon rupture and worsening of myasthenia gravis, causes QT prolongation and photosensitivity, and must be spaced $2\,\text{hours}$ before or $6\,\text{hours}$ after dairy/calcium/iron.

Tetracycline hydrochloride

A broad-spectrum antibiotic prototype that interferes with microbial protein synthesis, used for Mycoplasma, Chlamydia, Rickettsia, and Lyme disease. Causes permanent teeth discoloration and bone growth inhibition (contraindicated under $8\,\text{years}$ of age), worsens renal failure, and decreases oral contraceptive effectiveness.

Trimethoprim-sulfamethoxazole (Bactrim, Septra)

A sulfonamide prototype combination that blocks bacterial multiplication, commonly indicated for Pneumocystis jiroveci pneumonia and urinary tract infections. Nursing implications include common allergic reactions, decreased contraceptive efficacy, and contraindications in breastfeeding and renal failure.

Nitrofurantoin (Macrobid, Macrodantin)

A urinary antiseptic prototype utilized as adjuvant therapy for urinary tract infections (UTIs). It is contraindicated in pregnancy and poor kidney function, and patients should be counseled that their urine may turn brown.

Erythromycin

A macrolide prototype that binds bacterial ribosomes to stop protein synthesis, serving as a penicillin substitute and ophthalmic ointment to prevent neonatal conjunctivitis. Carries risks of hepatic failure (no renal dose adjustments needed), mood changes, and pseudomembranous colitis (CDAD).

Clindamycin (Cleocin)

An antibacterial agent active against anaerobes such as Bacteroides fragilis and gram-positive organisms, used as a penicillin alternative. Carries a black box warning for causing severe pseudomembranous colitis (Clostridium difficile-associated diarrhea).

Vancomycin (Vancocin)

A glycopeptide antibiotic active only against gram-positive pathogens (MRSA, MSSA, and orally for C. diff). Requires slow IV infusion over $1\text{--}2\,\text{hours}$ to prevent 'red man syndrome' flushing, requires renal dose adjustments, and mandates therapeutic monitoring of serum trough levels.

Red Man Syndrome

A histamine-mediated adverse reaction caused by rapid intravenous infusion of vancomycin, characterized by intense facial, neck, and upper torso flushing and erythema; prevented by infusing slowly over at least $1\text{--}2\,\text{hours}$.

Linezolid (Zyvox)

An oxazolidinone antibiotic active only against gram-positive organisms, specifically reserved for VRE and MRSA. Carries a black box warning for potentially fatal serotonin syndrome when co-administered with serotonergic agents, and causes myelosuppression (anemia).

Pseudomembranous Colitis (CDAD)

Severe colon inflammation and swelling triggered by an overgrowth of Clostridium difficile following antibiotic therapy (particularly clindamycin or macrolides), presenting with severe diarrhea, dehydration, and a characteristic strong fecal odor.

Peak Serum Drug Level

The highest drug concentration in the bloodstream during therapeutic drug monitoring, measured $15\text{--}30\,\text{minutes}$ after completing an intravenous infusion of drugs such as gentamicin or vancomycin.

Trough Serum Drug Level

The lowest drug concentration in the bloodstream during therapeutic drug monitoring, measured $15\text{--}30\,\text{minutes}$ immediately before the next scheduled dose to avoid drug accumulation and toxicity.

Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antimicrobial agent that completely inhibits the visible growth of a targeted bacterial strain in vitro.

Bactericidal vs. Bacteriostatic

Bactericidal agents directly kill bacteria, whereas bacteriostatic antimicrobial agents inhibit bacterial growth, replication, and multiplication, allowing the host immune system to eliminate the pathogen.

Mantoux Tuberculin Skin Test (TST)

A diagnostic intradermal injection of tuberculin purified protein derivative used to screen for tuberculosis exposure. Interpretation requires measuring only the raised induration in millimeters across the forearm, never the surrounding erythema.

Directly Observed Therapy (DOT)

A tuberculosis treatment strategy in which a healthcare worker directly observes the patient swallowing each medication dose, highly recommended to manage complex multi-drug regimens and ensure patient adherence.

Rifampin (Rifadin)

A rifamycin prototype that inhibits RNA synthesis, used alone for latent tuberculosis and in multidrug combinations for active tuberculosis. It causes a harmless red-orange discoloration of bodily fluids, carries risks of hepatotoxicity and renal failure, and acts as a potent CYP450 enzyme inducer.

CYP450 Enzyme Inducer

A substance (such as rifampin) that accelerates the enzymatic activity and synthesis of hepatic cytochrome P450 enzymes, resulting in rapid metabolism, lower plasma concentrations, and diminished therapeutic effects of co-administered drugs.

Isoniazid (INH)

A core anti-tuberculosis prototype that inhibits bacterial cell wall synthesis, selectively targeting mycobacteria alone in latent TB or in combination for active TB. Causes hepatotoxicity (monitored by jaundice and elevated LFTs) and peripheral neuropathy, which is countered with pyridoxine (vitamin B6).

Pyrazinamide

An essential first-line antitubercular agent used in R.I.P.E. combination therapy for active tuberculosis, notable for its significant risk of hepatotoxicity.

Ethambutol

A first-line antitubercular medication forming the 'E' in the R.I.P.E. regimen for tuberculosis, characterized by its distinctive adverse effect of optic neuritis.

Methicillin-Resistant Staphylococcus aureus (MRSA)

A high-resistance strain of gram-positive Staphylococci that evades beta-lactam antibiotics via beta-lactamase production and altered penicillin-binding proteins (PBPs), commonly treated with vancomycin.

Acquired Antibiotic Resistance

The process by which susceptible bacterial populations exposed to antimicrobial pressures are eliminated, allowing spontaneously mutated or resistant bacteria to survive, multiply, and transfer drug-resistance traits to other bacteria.

Gram-Positive vs. Gram-Negative Cell Wall

Gram-positive bacteria possess a thick outer peptidoglycan cell wall (e.g., Staphylococci, Streptococci), whereas gram-negative bacteria possess an outer protective lipid bilayer membrane (e.g., E. coli, Pseudomonas aeruginosa, Klebsiella).