What Happens When Antibiotics Stop Working?

Nov. 15, 2018

As bacteria accumulate multiple drug resistance characteristics, fewer and fewer drugs are available to treat sick patients. A worst-case scenario is playing out right now in southeast and central Asia, where multidrug-resistant Salmonella enterica serovar Typhi is causing massive outbreaks of typhoid fever. Typhoid fever is a life-threatening illness spread by S. enterica serovar Typhi through poor sanitation and contaminated water.
 
The circulating H58 lineage strain is known for its ability to cause serious disease and displace other strains. A recently identified Sindh strain, so called because of an epidemic it caused in Sindh, Pakistan, carries both chromosomal and plasmid-borne resistance to all major first-line oral antibiotics except azithromycin. Patients cannot be treated with chloramphenicol, amoxicillin, ampicillin, TMP-SMZ, ciprofloxacin or other fluoroquinolones, or ceftriaxone; an independently circulating azithromycin-resistant S.enterica serovar Typhi strain suggests the possibility that the Sindh strain may gain resistance to this last oral antibiotic. 

If the strain becomes resistant to all oral antibiotics, there are still drug options, such as carbapenem and tigecycline-class antibiotics, but their widespread use in low-resource countries is unrealistic. Not only do these drugs cost more themselves, but they require intravenous injection or infusion, necessitating additional health care cost burdens that low-resource countries are unlikely to be able to bear. Before the antibiotic era, typhoid fever had a 15% fatality rate. Should azithromycin fail, morbidity and mortality of this now-treatable disease will assuredly increase.

Don't miss our previous installment of our World Antibiotic Awareness Week blog posts, where we asked, "how do antibiotics in agriculture affect human clinical infectious disease?" In our next post, we'll address "what can we do to stop the spread of drug-resistant infections?"

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Author: Julie Wolf

Julie Wolf
Dr. Julie Wolf is in science communications at Indie Bio, and was a former ASM employee. Follow Julie on Twitter for more ASM and microbiology highlights at @JulieMarieWolf.