A viral disease (or viral infection) occurs when an organisms body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. Structural Characteristics
Basic structural characteristics, such as genome type, virion shape and replication site, generally share the same features among virus species within the same family. Double-stranded DNA families: three are non-enveloped (Adenoviridae, Papillomaviridae and Polyomaviridae) and two are enveloped (Herpesviridae and Poxviridae). All of the non-enveloped families have icosahedral capsids. Partly double-stranded DNA viruses: Hepadnaviridae. These viruses are enveloped. One family of single-stranded DNA viruses infects humans: Parvoviridae. These viruses are non-enveloped. Positive single-stranded RNA families: three non-enveloped (Astroviridae, Caliciviridae and Picornaviridae) and four enveloped (Coronaviridae, Flaviviridae, Retroviridae and Togaviridae). All the non-enveloped families have icosahedral nucleocapsids. Negative single-stranded RNA families: Arenaviridae, Bunyaviridae, Filoviridae, Orthomyxoviridae, ParamyxoviridaeParamyxoviridae and Rhabdoviridae. All are enveloped with helical nucleocapsids. Double-stranded RNA genome: Reoviridae. The Hepatitis D virus has not yet been assigned to a family, but is clearly distinct from the other families infecting humans. Viruses known to infect humans that have not been associated with disease: the family Anelloviridae and the genus Dependovirus. Both of these taxa are non-enveloped single-stranded DNA viruses. Pragmatic Rules
Human-infecting virus families offer rules that may assist physicians and medical microbiologists/virologists.As a general rule, DNA viruses replicate within the cell nucleus while RNA viruses replicate within the cytoplasm. Exceptions are known to this rule: poxviruses replicate within the cytoplasm and orthomyxoviruses and hepatitis D virus (RNA viruses) replicate within the nucleus.
Mafenide (INN; usually as mafenide acetate, trade name Sulfamylon) is a sulfonamide-type medication used as an antibiotic. It was approved by the FDA in 1948. Uses
Mafenide is used to treat severe burns. It is used topically as an adjunctive therapy for second- and third-degree burns. It is bacteriostatic against many gram-positive and gram-negative organisms, including Pseudomonas aeruginosa. Some sources state that mafenide is more appropriate for non-facial burns, while chloramphenicol/prednisolone or bacitracin are more appropriate for facial burns. Mechanism of action
Mafenide works by reducing the bacterial population present in the avascular tissues of burns and permits spontaneous healing of deep partial-thickness burns. Adverse reactions
Adverse reactions can include superinfection, pain or burning upon application, rash, pruritus, tachypnea, or hyperventilation. Mafenide is metabolized to a carbonic anhydrase inhibitor, which could potentially result in metabolic acidosis. Drug interactions
There are no significant interactions. Contraindications
Mafenide is contraindicated in those with sulfonamide hypersensitivity or renal impairment. Dosage
For use as adjunctive therapy for second- and third-degree burns to prevent infection, adults and children should apply topically to a thickness of approximately 1.6 mm to cleaned and debrided wound once or twice per day with a sterile gloved hand. The burned area should be covered with cream at all times. References
External links
Mafenide information on RxList