Editing Tuberculosis (section)

=== Medication resistance ===

Primary resistance occurs when a person becomes infected with a resistant strain of TB. A person with fully susceptible [[Mycobacterium tuberculosis|MTB]] may develop secondary (acquired) resistance during therapy because of inadequate treatment, not taking the prescribed regimen appropriately (lack of compliance), or using low-quality medication.<ref>{{cite journal | vauthors = O'Brien RJ | title = Drug-resistant tuberculosis: etiology, management and prevention | journal = Seminars in Respiratory Infections | volume = 9 | issue = 2 | pages = 104–12 | date = June 1994 | pmid = 7973169 }}</ref> Drug-resistant TB is a serious public health issue in many developing countries, as its treatment is longer and requires more expensive drugs. MDR-TB is defined as resistance to the two most effective first-line TB drugs: rifampicin and isoniazid. Extensively drug-resistant TB is also resistant to three or more of the six classes of second-line drugs.<ref>{{cite journal | author = Centers for Disease Control and Prevention (CDC) | title = Emergence of Mycobacterium tuberculosis with extensive resistance to second-line drugs—worldwide, 2000–2004 | journal = MMWR. Morbidity and Mortality Weekly Report | volume = 55 | issue = 11 | pages = 301–5 | date = March 2006 | pmid = 16557213 | url = https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5511a2.htm | url-status = live | archive-url = https://web.archive.org/web/20170522030229/https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5511a2.htm | archive-date = 22 May 2017 }}</ref> Totally drug-resistant TB is resistant to all currently used drugs.<ref name="McKenna-2012">{{Cite magazine|title=Totally Resistant TB: Earliest Cases in Italy|magazine=Wired|url=https://www.wired.com/wiredscience/2012/01/tdr-first-Italy/| vauthors = McKenna M |date=12 January 2012|access-date=12 January 2012|url-status=live|archive-url=https://web.archive.org/web/20120114214156/http://www.wired.com/wiredscience/2012/01/tdr-first-Italy/|archive-date=14 January 2012}}</ref> It was first observed in 2003 in Italy,<ref>{{cite journal | vauthors = Migliori GB, De Iaco G, Besozzi G, Centis R, Cirillo DM | title = First tuberculosis cases in Italy resistant to all tested drugs | journal = Euro Surveillance | volume = 12 | issue = 5 | pages = E070517.1 | date = May 2007 | pmid = 17868596 | doi = 10.2807/esw.12.20.03194-en | doi-access = free }}</ref> but not widely reported until 2012,<ref name="McKenna-2012" /><ref>{{cite web|title=Totally Drug-Resistant TB: a WHO consultation on the diagnostic definition and treatment options|url=https://www.who.int/tb/challenges/xdr/Report_Meeting_totallydrugresistantTB_032012.pdf?ua=1|publisher=World Health Organization (WHO)|access-date=25 March 2016|url-status=live|archive-url=https://web.archive.org/web/20161021151601/http://www.who.int/tb/challenges/xdr/Report_Meeting_totallydrugresistantTB_032012.pdf?ua=1|archive-date=21 October 2016}}</ref> and has also been found in Iran and India.<ref name="Kielstra-2014">{{cite news | title = Ancient enemy, modern imperative – A time for greater action against tuberculosis | newspaper = The Economist |url=http://www.economistinsights.com/sites/default/files/Ancient%20enemy%20modern%20imperative.pdf |publisher=[[Economist Intelligence Unit]]|access-date=22 January 2022|date=30 June 2014| vauthors = Kielstra P | veditors = Tabary Z |archive-url=https://web.archive.org/web/20140810101716/http://www.economistinsights.com/sites/default/files/Ancient%20enemy%20modern%20imperative.pdf |archive-date=10 August 2014}}</ref> There is some efficacy for [[linezolid]] to treat those with XDR-TB but side effects and discontinuation of medications were common.<ref>{{cite journal | vauthors = Singh B, Cocker D, Ryan H, Sloan DJ | title = Linezolid for drug-resistant pulmonary tuberculosis | journal = The Cochrane Database of Systematic Reviews | volume = 3 | pages = CD012836 | date = March 2019 | issue = 3 | pmid = 30893466 | pmc = 6426281 | doi = 10.1002/14651858.CD012836.pub2 | collaboration = Cochrane Infectious Diseases Group }}</ref><ref>{{cite journal | vauthors = Velayati AA, Masjedi MR, Farnia P, Tabarsi P, Ghanavi J, ZiaZarifi AH, Hoffner SE | title = Emergence of new forms of totally drug-resistant tuberculosis bacilli: super extensively drug-resistant tuberculosis or totally drug-resistant strains in Iran | journal = Chest | volume = 136 | issue = 2 | pages = 420–425 | date = August 2009 | pmid = 19349380 | doi = 10.1378/chest.08-2427 }}</ref> [[Bedaquiline]] is tentatively supported for use in multi-drug resistant TB.<ref>{{cite web|title=Provisional CDC Guidelines for the Use and Safety Monitoring of Bedaquiline Fumarate (Sirturo) for the Treatment of Multidrug-Resistant Tuberculosis|url=https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6209a1.htm?s_cid=rr6209a1_x|url-status=live|archive-url=https://web.archive.org/web/20140104204359/http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6209a1.htm?s_cid=rr6209a1_x|archive-date=4 January 2014}}</ref>

XDR-TB is a term sometimes used to define ''extensively resistant'' TB, and constitutes one in ten cases of MDR-TB. Cases of XDR TB have been identified in more than 90% of countries.<ref name="Kielstra-2014" />

For those with known rifampicin or MDR-TB, molecular tests such as the Genotype MTBDRsl Assay (performed on culture isolates or smear positive specimens) may be useful to detect second-line anti-tubercular drug resistance.<ref>{{cite journal | vauthors = Theron G, Peter J, Richardson M, Warren R, Dheda K, Steingart KR | title = ® MTBDRsl assay for resistance to second-line anti-tuberculosis drugs | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | pages = CD010705 | date = September 2016 | issue = 9 | pmid = 27605387 | pmc = 5034505 | doi = 10.1002/14651858.CD010705.pub3 | collaboration = Cochrane Infectious Diseases Group }}</ref><ref>{{cite web |url=https://www.who.int/tb/WHOPolicyStatementSLLPA.pdf |title=The use of molecular line probe assays for the detection of resistance to second-line anti-tuberculosis drugs |website=World Health Organization |access-date=18 June 2021 |archive-date=22 September 2021 |archive-url=https://web.archive.org/web/20210922003541/https://www.who.int/tb/WHOPolicyStatementSLLPA.pdf |url-status=live }}</ref>

Xpert MTB/XDR can be used to detect resistance of isoniazid, fluoroquinolones, and amikacin and can be helpful in selection of optimal medication.<ref>{{Cite journal |last1=Pillay |first1=Samantha |last2=Steingart |first2=Karen R |last3=Davies |first3=Geraint R |last4=Chaplin |first4=Marty |last5=De Vos |first5=Margaretha |last6=Schumacher |first6=Samuel G |last7=Warren |first7=Rob |last8=Theron |first8=Grant |date=2022-05-18 |editor-last=Cochrane Infectious Diseases Group |title=Xpert MTB/XDR for detection of pulmonary tuberculosis and resistance to isoniazid, fluoroquinolones, ethionamide, and amikacin |journal=Cochrane Database of Systematic Reviews |language=en |volume=2022 |issue=5 |pages=CD014841 |doi=10.1002/14651858.CD014841.pub2 |pmc=9115865 |pmid=35583175}}</ref>