2008 ICD-9-CM Volume 1 Diagnosis Codes Home > Supplementary Classification Of Factors Influencing Health Status And Contact With Health Services V01-V86 > Persons With Potential Health Hazards Related To Communicable Diseases V01-V09 > Infection With Drug-Resistant Microorganisms V09.* > 2008 ICD-9-CM Diagnosis V09.91 Infection with drug-resistant microorganisms unspecified with multiple drug resistance  On October 1, 2008 the 2009 ICD-9-CM codes came into effect. Therefore, this code may be out of date. The 2009 version of ICD-9-CM V09.91 can be accessed here. Adaptation of tumor cells to anticancer drugs in ways that make the drugs less effective. Simultaneous resistance to a spectrum of unrelated drugs following exposure to a single agent. It may result from overexpression of the integral plasma membrane protein, P-glycoprotein. This adaptation of tumor cells to anticancer drugs, mediated by inactivation of the drug or removing it from the target tumor cells, tends to make the drugs less effective. Simultaneous resistance to several structurally and functionally distinct drugs. V09.91 is a specific code that can be used to specify a diagnosis V09.91 contains 2 index entries View the ICD-9-CM Volume 1 V09.* hierarchy ICD9Data's sister site ProcedureCodes.com launches with the 2008/09 CPT® codes - read more on the ICD9Data.com blog. V09.91 also known as: Multiple drug resistance NOS Index entries containing V09.91: Resistance, resistant (to) drugs by microorganisms V09.90 MDRO (multiple drug resistant organisms ) NOS V09.91 multiple drug resistant organisms NOS V09.91