BACKGROUND: Enteric fever is a major global problem. Emergence of antibacterial resistance threatens to render current treatments ineffective. There is little research or public health effort directed toward Salmonella enterica serovar Paratyphi A, because it is assumed to cause less severe enteric fever than does S. enterica serovar Typhi. There are few data on which to base this assumption, little is known of the serovar's antibacterial susceptibilities, and there is no readily available tolerable vaccination. METHODS: A prospective study was conducted of 609 consecutive cases of enteric fever (confirmed by blood culture) to compare the clinical phenotypes and antibacterial susceptibilities in S. Typhi and S. Paratyphi A infections. Variables independently associated with either infection were identified to develop a diagnostic rule to distinguish the infections. All isolates were tested for susceptibility to antibacterials. RESULTS: Six hundred nine patients (409 with S. Typhi infection and 200 with S. Paratyphi A infection) presented during the study period. The infections were clinically indistinguishable and had equal severity. Nalidixic acid resistance, which predicts a poor response to fluoroquinolone treatment, was extremely common (75.25% of S. Paratyphi A isolates and 50.5% of S. Typhi isolates; P < .001). S. Paratyphi A was more likely to be resistant to ofloxacin (3.6% vs. 0.5%; P = .007) or to have intermediate susceptibility to ofloxacin (28.7% vs. 1.8%; P < .001) or ciprofloxacin (39.4% vs. 8.2%; P < .001). MICs for S. Paratyphi A were higher than for S. Typhi (MIC of ciprofloxacin, 0.75 vs. 0.38 microg/mL [P < .001]; MIC of ofloxacin, 2.0 vs. 0.75 microg/mL [P < .001]). CONCLUSIONS: The importance of S. Paratyphi A has been underestimated. Infection is common, the agent causes disease as severe as that caused by S. Typhi and is highly likely to be drug resistant. Drug resistance and lack of effective vaccination suggest that S. Paratyphi A infection may become a major world health problem.
BACKGROUND: Enteric fever is a major global problem. Emergence of antibacterial resistance threatens to render current treatments ineffective. There is little research or public health effort directed toward Salmonella enterica serovar Paratyphi A, because it is assumed to cause less severe enteric fever than does S. enterica serovar Typhi. There are few data on which to base this assumption, little is known of the serovar's antibacterial susceptibilities, and there is no readily available tolerable vaccination. METHODS: A prospective study was conducted of 609 consecutive cases of enteric fever (confirmed by blood culture) to compare the clinical phenotypes and antibacterial susceptibilities in S. Typhi and S. Paratyphi Ainfections. Variables independently associated with either infection were identified to develop a diagnostic rule to distinguish the infections. All isolates were tested for susceptibility to antibacterials. RESULTS: Six hundred nine patients (409 with S. Typhi infection and 200 with S. Paratyphi Ainfection) presented during the study period. The infections were clinically indistinguishable and had equal severity. Nalidixic acid resistance, which predicts a poor response to fluoroquinolone treatment, was extremely common (75.25% of S. Paratyphi A isolates and 50.5% of S. Typhi isolates; P < .001). S. Paratyphi A was more likely to be resistant to ofloxacin (3.6% vs. 0.5%; P = .007) or to have intermediate susceptibility to ofloxacin (28.7% vs. 1.8%; P < .001) or ciprofloxacin (39.4% vs. 8.2%; P < .001). MICs for S. Paratyphi A were higher than for S. Typhi (MIC of ciprofloxacin, 0.75 vs. 0.38 microg/mL [P < .001]; MIC of ofloxacin, 2.0 vs. 0.75 microg/mL [P < .001]). CONCLUSIONS: The importance of S. Paratyphi A has been underestimated. Infection is common, the agent causes disease as severe as that caused by S. Typhi and is highly likely to be drug resistant. Drug resistance and lack of effective vaccination suggest that S. Paratyphi Ainfection may become a major world health problem.
Authors: Kathryn E Holt; Stephen Baker; Sabina Dongol; Buddha Basnyat; Neelam Adhikari; Stephen Thorson; Anoop S Pulickal; Yajun Song; Julian Parkhill; Jeremy J Farrar; David R Murdoch; Dominic F Kelly; Andrew J Pollard; Gordon Dougan Journal: BMC Infect Dis Date: 2010-05-31 Impact factor: 3.090
Authors: Abhilasha Karkey; Amit Arjyal; Katherine L Anders; Maciej F Boni; Sabina Dongol; Samir Koirala; Phan Vu Tra My; Tran Vu Thieu Nga; Archie C A Clements; Kathryn E Holt; Pham Thanh Duy; Jeremy N Day; James I Campbell; Gordon Dougan; Christiane Dolecek; Jeremy Farrar; Buddha Basnyat; Stephen Baker Journal: PLoS One Date: 2010-11-15 Impact factor: 3.240
Authors: Mohammad Murshid Alam; Lillian L Tsai; Sean M Rollins; Alaullah Sheikh; Farhana Khanam; Meagan Kelly Bufano; Yanan Yu; Ying Wu-Freeman; Anuj Kalsy; Tania Sultana; M Abu Sayeed; Nusrat Jahan; Regina C LaRocque; Jason B Harris; Daniel T Leung; W Abdullah Brooks; Stephen B Calderwood; Richelle C Charles; Firdausi Qadri; Edward T Ryan Journal: Clin Vaccine Immunol Date: 2013-03-13
Authors: Tran Vu Thieu Nga; Abhilasha Karkey; Sabina Dongol; Hang Nguyen Thuy; Sarah Dunstan; Kathryn Holt; Le Thi Phuong Tu; James I Campbell; Tran Thuy Chau; Nguyen Van Vinh Chau; Amit Arjyal; Samir Koirala; Buddha Basnyat; Christiane Dolecek; Jeremy Farrar; Stephen Baker Journal: BMC Infect Dis Date: 2010-05-21 Impact factor: 3.090
Authors: Mark D Zimmerman; David R Murdoch; Patrick J Rozmajzl; Buddha Basnyat; Christopher W Woods; Allen L Richards; Ram Hari Belbase; David A Hammer; Trevor P Anderson; L Barth Reller Journal: Emerg Infect Dis Date: 2008-10 Impact factor: 6.883