Ecological balance and disturbance in the oropharyngeal and gastrointestinal microflora

C. Stark, C. Edlund and C.E. Nord
Department of Immunology, Microbiology, Pathology and Infectious Diseases, Huddinge University Hospital, Karolinska Institute, Sweden.

SUMMARY
The indigenous human oropharyngeal and gastrointestinal microflora is involved in a complex ecosystem which has a symbiotic relationship with the host. This microflora helps to prevent invasion of potentially pathogenic microorganisms. The exposure of antimicrobial agents may disturb the ecological balance of the normal microflora. This influence often leads to decreased colonization resistance due to repression of sensitive bacteria and selection of resistant bacteria which may acquire resistance during therapy. The potential of an antimicrobial agent to have an impact on the normal microflora is related to the agent's antibacterial spectrum, route of administration, pharmacokinetic properties and the degree of inactivation in vivo. This should be considered when antimicrobial agents are used for treatment and prophylaxis of infections. The present article refers to the ecological effects on the normal microflora after administration of beta-lactam agents, tetracyclines, clindamycin, nitroimidazoles, quinolones, macrolides and effect of omeprazole on the gastric and intestinal microflora.
Key words: Oropharyngeal and gastrointestinal microflora - Antimicrobials - Resistance

Equilibrio ecol�gico y alteraci�n en la microflora orofar�ngea y gastrointestinal

RESUMEN
La microflora humana orofar�ngea y gastrointestinal tiene un complejo ecosistema que se relaciona simbi�ticamente con el organismo. Esta microflora ayuda a impedir la invasi�n de microorganismos con potencial patog�nico. La exposici�n a los agentes antibacterianos puede alterar el equilibrio ecol�gico de la microflora normal. Esta influencia conduce frecuentemente a una resistencia reducida de colonizaci�n debido a la represi�n de las bacterias sensibles y la selecci�n de bacterias resistentes a lo largo de la terapia. La potencia de un antibacteriano sobre la microflora normal est� relacionada con el espectro antibacteriano, la v�a de administraci�n, las caracter�sticas farmacocin�ticas del agente y el grado de inactivaci�n in vivo. Todo esto debe ser considerado cuando se utilizan agentes antibacterianos para el tratamiento y la profilaxis de las infecciones. Este art�culo trata de los efectos ecol�gicos sobre la microflora normal despu�s de la administraci�n de betalact�micos, tetraciclinas, clindamicina, nitroimidazoles, quinolonas y macr�lidos, y tambi�n del efecto del omeprazol sobre la microflora g�strica e intestinal.
Palabras clave: Microflora orofar�ngea y gastrointestinal - Antibacterianos - Resistencia

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