Emergence of Ceftriaxone Resistant Salmonella Typhi in Pakistan: New resistance mechanism and plasmid acquired by Salmonella Typhi
A new resistant strain of Salmonella Typhi has emerged in Pakistan, further narrowing the antibiotic choices available for treatment of typhoid. The strain is similar to previous circulating H58 strain in Pakistan but has acquired a new plasmid with additional resistant genes for a) cephalosporins (CTX-M), making it highly resistant to all available third and fourth generation cephalosporins, and b) quinolone resistance (qnr). Spread of this clone has led to an outbreak in Hyderabad, Pakistan, and possible spread to other cities. Emergence of this new extended spectrum beta lactamase producing Salmonella Typhi is a sentinel event and an alarming occurrence.
Detection of the outbreak was possible through continued AMR surveillance by clinical microbiologists involved. Experts have stressed on avoidance of irrational use of antibiotics, and availability and use of clean water for drinking.
The following article reports the emergence and molecular mechanism: