ANTIBIOTICS

ANTIBACTERIALS - ANTIMYCOBACTERIALS

DRUGS COMMONLY used, prescribed or else met with in oral / dental practice are italized, and often further described in a tabular display.
ADVERSE EFFECTS, including oral lesions, are - sporadically, but as a continuing feature - added after the drug group or single drug name. They are originally written in red. Note, however, that colours may change with user preferences and links.
LETTERS-NUMBERS in parenthesis refer to the ATC classification.

Antibiotics - here taken in the sense of Antibacterials and Antimycobacterials - may work by inhibiting specific steps in

bacterial cell wall synthesis (betalactam antibiotics: penicillins, cephalosporins, tienamycines = carbapenems; streptogramines and glycopeptides). Along this way, they thus neither affect human cells, nor infectious agents which - like e.g. mycoplasmas, rickettsiae and chlamydiae - lack cell walls.
bacterial protein synthesis (aminoglycosides, macrolides, lincosamides, streptogramines, tetracyclines),
bacterial mRNA synthesis (rifamycins), or
bacterial DNA function, synthesis and replication (antifolates as sulphonamides, sulphones, trimethoprim, nitroimidazoles, quinilones).

The last two mechanisms are akin to those used to damage malignant human cells by several antineoplastic drugs.

Resistance of bacteria to drug treatment may be either inherent = native, or induced; the latter often as a consequence of either mutation(s) or incorporation of new genetic material (transposones; directly = transformation, as plasmids = conjugation, or by way of bacteriophages = transduction). Examples of such changes are found among an increasing number of bacterial species; including staphylococci, gonococci, enterobacteria, Haemophilus influenzae and Bacteroides fragilis. The resultant resistance imparting mechanisms are foremost

the induction of new enzymes - here in particular the betalactamases (penicillinases, cephalosporinases). This mechanism may be counteracted by specific inhibitors - e.g. clavulanate, sulbactam and tazobactam - which all contain a beta lactam ring, work by competetive inhibition and are available in combined preparations.
the destruction of surface openings (pores) which disallows the antibiotic drug access to the inside of the bacteria; and
the rearrangement of special bacterial proteins - here in particular the so called penicillin binding proteins (PBPs) - which are instrumental in building the peptidoglycan layer of the bacterial cell wall. This particular mechanism is at work in the methicillin resistant staphylococcus aureus (MRSAs).

Bacterial resistance or susceptibility is classically evaluated by lowest dose of a drug which, as measured under laboratory conditions and expressed in e.g. mg/L following dilution methods, or mm following agar diffusion methods,

inhibits bacterial growth is called the Minimum Inhibitory Concentration = MIC
kills bacteria is called the Minimum Bactericidal Concentration = MBC.

Susceptibility = sensitivity tests will always underlie ultimate therapeutic choices among available antibiotics. At first application, however - which in oral contexts should always be preceded by or occur in parallel with mechanical measures to clean, ream, debride and/or drain the affected area - the site of infection and contraindications in terms of age or pregnancy, allergies / hypersensitivity, associated (kidney or liver) diseases and drug interactions will have to be considered.

A routine prophylactic use of antibiotics in connection with dental treatments to counteract systemic infections is now less often recommended; indications being restricted to active infections of type infective endocarditis and in connection with prosthetic joint replacements (see Further reading).

A general adverse effect of antibiotics is the risk for superimposed infections; by e.g. fungi or the toxin-producing intestinal bacillus Clostridium difficile; the enteritis caused by the latter usually being treated with e.g. metronidazole (a nitroimidazole, which works through metabolites binding to DNA) or vancomycin (a glycopeptide which inhibits cell wall synthesis in Gram+ bacteria). All antibiotics may further enhance the effect of oral anticoagulants, and reduce the effect of oral contraceptives; the latter mechanism being that they interfere with the bacterial breakdown of steroid conjugates, and thus the reabsorption of active steroids.

In the ATC classification, (J01) signifies antibiotics for systemic use.

Aminoglycosides (J01G) - not absorbed from GI tract; against aerobic Gram- bacteria (except streptococci) - nephrotoxic and ototoxic
amikacin (J01GB06), gentamicin (D06AX07; J01GB03; from Micromonospora), netilmicin (J01GB07), neomycin, streptomycin, tobramycin (J01GB01; Streptomyces)

Amphenicols (J01B) - act intracellularly; by blocking peptidyl transferase - dose dependent myelosuppression
chloramphenicol (J01BA01), thiamphenicol

Antifolates; including Sulphonamides (J01E) and Sulphones - the first synthetic antibacterial drugs; made available in the 1930ies - potentially allergic, skin reactions ranging from pruritic rashes to severe toxic epidermal necrolysis; contraindicated in pregnancy and renal disease. Sulphonamides enhance the effect or oral anticoagulants and hypoglycaemic agents.
dapsone ( = diaminodiphenyl sulphone = DDS = a sulphone), sulphacetamide, sulphadiazine, sulphadimidine, sulphafurazole, sulphamethoxazole; and the dihydrofolate reductase (DHFR) inhibitors trimethoprim (J01EA01), pyrimethamine and trimetrexate. Examples of combined preparations are trimethoprim + sulphamethoxazole (J01EE01;TMP-SMZ or co-trimoxazole) and trimethoprim + sulphadiazine (J01EE02)

Betalactams
Primarily the

Penicillins (J01C) -include the first penicillin; discovered by A Fleming in 1928. They are the main agents for streptococcal, meningococcal and staphylococcal infections, and the first choice for oral infections - and then especially phenoxymethylpenicillin. Obs pro penicillin allergies / hypersensitivity.

There are three main groups of penicillins:

penicillinase = beta lactamase sensitive (J01CE; standard): benzylpenicillin (J01CE01; penicillin G; SIM or SIV), procaine penicillin (SIM; for depots), benzathine penicillin - all for parenteral use; phenoxymethylpenicillin (J01CE02; penicillin V; SPO)
broadspectrum (J01CA), which include the aminopenicillins; and amongst them ureidopenicillins which have now usually superseeded carboxypenicillins: amoxycillin = amoxicillin (J01CA04; SPO, SIM or SIV; rashes, diarrhoea), ampicillin (J01CA01; SPO, SIM or SIV), bakampicillin (J01CA06), mecillinam (J01CA011), piperazillin (J01CA012), pivampicillin (J01CA02), pivmecillinam (J01CA08)
penicillinase = beta lactamase stable / resistant (J01CF): cloxacillin (J01CF02), dicloxacillin (J01CF01), flucloxacillin (J01CF05; SPO, SIM) - all isoxazolylpenicillins; methicillin (the first in this group; for parenteral use; a severe adverse effect is allergic, interstitial nephritis)

Other betalactams (J01D); may crossreact with penicillin allergies / hypersensitivity

Cephalosporins (cefalosporins) and Related Betalactams (J01DA) - used in particular against aerobic Gram- bacteria; these drugs are penicillinase resistant, but not active against enterococci;
cephaclor, cephadroxil (J01DA09), cephalexine (J01DA01), cephamandole, cephazolin, cephipime (J01DA24), cephixime (J01DA23), cephodizime, cephodoxime (J01DA33), cefotaxime (J01DA10; SIM, SIV), cephoxitin (J01DA05; a cephamycin), cephradine, cephsulodin, ceftazidime (J01DA11; SIM, SIV), cephtibutene (J01DA39), cephtriaxone (J01DA13; SIM, SIV), cefuroxime (J01DA06; SIM, SIV), loracarbef (J01DA38)
Monobactams (J01DF) - against aerobic Gram- bacteria only; for parenteral use
aztreonam (J01DF01)
Tienamycines (J01DH) or Carbapenems - very broadspectrum and penicillinase resistant; for parenteral use
imipenem (J01Dh51), meropenem (J01DH02)

Glycopeptides (J01XA) - not absorbed from GI tract
teicoplanin (J01XA02; prophylaxis for endocarditis), vancomycin (J01XA01; for Gram+ bacteria; SO for pseudomembraneous colitis; or SIV as endocarditis prohylaxis)

MLS drugs (J01F)
Macrolides (J01FA) - especially in respiratory infections
azithromycin (J01FA10), clarithromycin (J01FA09), erythromycin (J01FA01; often recommended for penicillin allergic cases; dyspepsia, nausea, vomiting; also interactions), roxitromycin (J01FA06), spiramycin
Lincosamides (J01FF)
clindamycin (D10AF01; G01AA10; J01FF01; obs pro pseudomembraneous colitis), lincomycin (Streptomyces linconensis)
Streptogramins (J01FG) - against methicillin-resistant staphylococci, and vancomycin-resistant enterococci

Nitroimidazoles - against strict, especially Gram- anaerobs and certain protozoa (P01); contraindicated in pregnant women
- metronidazole (A01AB17, D06BX01, G01AF01, J01XD01, P01AB01), tinidazole (J01XD02, P01AB02)

Quinolones (J01M) - derivatives of nalidixic acid; against Gram- bacilli; contraindicated in pregnant women & children
ciprofloxacin (J01MA02), enoxacin, grepafloxacin, levofloxacin (J01MA12), lomefloxacin, moxifloxacin (J01MA14), norfloxacin (J01MA06), ofloxacin (J01MA01), trovafloxacin

Rifamycins - especially used, in multidrug regimens, against tuberculosis; and other mycobacterial infections. Induce hepatic microsomal enzymes and thus enhance the metabolism of other, simultaneously administered, drugs.
rifabutin (J04AB04), rifampicin (J04AB02), rifampin (rashes, thrombocytopenia, nephritis), rifamycin, rifaximin
See also Antimycobacterials below.

Steroids (J01XC) - fusidic acid = fusidine (J01XC01)

Tetracyclines (J01A) - act intracellularly by blocking tRNA binding to mRNA; broadspectrum, used especially against chlamydiae, mycoplasma, spirochaetal and rickettsial infections - may cause abdominal pain, potentiate photosensitivity and muscular weakness; contraindicated when there is a risk for their staining developing, mineralizing tissues; form chelates with - drugs containing - di- and trivalent cations (e.g. antacids); obs pro fungal superinfections
doxycycline (J01AA02), lymecycline (J01AA04), minocycline (against meningococci; will sometimes stain fully formed teeth and the oral mucosa), oxytetracycline (J01AA06), tetracycline (J01AA07)

Other antibacterial drugs
muciprocin (against staphylococcal - including S. aureus - and streptococcal skin infections), nitrofurantoin (J01XE01; urinary tract infections; peripheral neuropathy and pulmonary fibrosis), spectinomycin (gonorrhoea), polymyxins (extremely toxic when administered systemically)

ANTIMYCOBACTERIALS (J04)
clofazimine, dapsone, ethambutol (J04AK02; impaired colour vision), fluoroquinolones, isoniazid (J04AC01; isonicotinic acid hydrazine = INH; against M. tuberculosis; drug fever and skin rash, hepatitis, peripheral neuropathy, restlessness, psychosis), pyrazinamide, rifamycins, streptomycin

FURTHER READING
Tong DC, Rothwell BR. Antibiotic prophylaxis in dentistry: a review and practice recommendations. J Am Dent Assoc 2000;131:366-74. Medline abstract