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The clinical and microbiological characteristics of enteric fever in Cambodia, 2008-2015
Laura M F Kuijpers1,2, Thong Phe3, Chhun H Veng3
1Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
Background:
Enteric fever remains a major public health problem in low resource settings and antibiotic resistance is increasing. In Asia, an increasing proportion of infections is caused by Salmonella enterica serovar Paratyphi A, which for a long time was assumed to cause a milder clinical syndrome compared to Salmonella enterica serovar Typhi.
Methodology:
A retrospective chart review study was conducted of 254 unique cases of blood culture confirmed enteric fever who presented at a referral adult hospital in Phnom Penh, Cambodia between 2008 and 2015. Demographic, clinical and laboratory data were collected from clinical charts and antibiotic susceptibility testing was performed. Whole genome sequence analysis was performed on a subset of 121 isolates.
Results:
One-hundred-and-ninety unique patients were diagnosed with Salmonella Paratyphi A and 64 with Salmonella Typhi. In the period 2008-2012, Salmonella Paratyphi A comprised 25.5% of 47 enteric fever cases compared to 86.0% of 207 cases during 2013-2015. Presenting symptoms were identical for both serovars but higher median leukocyte counts (6.8 x 109/L vs. 6.3 x 109/L; p = 0.035) and C-reactive protein (CRP) values (47.0 mg/L vs. 36 mg/L; p = 0.034) were observed for Salmonella Typhi infections. All but one of the Salmonella Typhi isolates belonged to haplotype H58 associated with multidrug resistance (MDR) (i.e. resistance to ampicillin, chloramphenicol and co-trimoxazole).;42.9% actually displayed MDR compared to none of the Salmonella Paratyphi A isolates. Decreased ciprofloxacin susceptibility (DCS) was observed in 96.9% (62/64) of Salmonella Typhi isolates versus 11.5% (21/183) of Salmonella Paratyphi A isolates (all but one from 2015). All isolates were susceptible to azithromycin and ceftriaxone.
Conclusions:
In Phnom Penh, Cambodia, Salmonella Paratyphi A now causes the majority of enteric fever cases and decreased susceptibility against ciprofloxacin is increasing. Overall, Salmonella Typhi was significantly more associated with MDR and DCS compared to Salmonella Paratyphi A.
Insights
Salmonella Paratyphi A now causes most enteric fever in Cambodia, with increasing ciprofloxacin resistance. Salmonella Typhi showed higher rates of multidrug resistance and decreased ciprofloxacin susceptibility.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Public health in Asia
Background:
- Enteric fever is a significant public health issue in low-resource settings, exacerbated by rising antibiotic resistance.
- Salmonella enterica serovar Paratyphi A is increasingly implicated in Asian infections, previously thought to cause milder illness than Salmonella enterica serovar Typhi.
Purpose of the Study:
- To compare the clinical and microbiological features of Salmonella Paratyphi A and Salmonella Typhi infections in Phnom Penh, Cambodia.
- To assess trends in antibiotic resistance, including multidrug resistance (MDR) and decreased ciprofloxacin susceptibility (DCS), for both serovars.
Main Methods:
- Retrospective chart review of 254 blood culture-confirmed enteric fever cases (2008-2015) at a Phnom Penh hospital.
- Collection of demographic, clinical, and laboratory data, including antibiotic susceptibility testing.
- Whole genome sequencing of 121 isolates to analyze genetic relatedness and resistance mechanisms.
Main Results:
- Salmonella Paratyphi A cases increased from 25.5% (2008-2012) to 86.0% (2013-2015).
- Salmonella Typhi infections showed higher median leukocyte and C-reactive protein levels.
- All but one Salmonella Typhi isolate belonged to MDR-associated haplotype H58; 42.9% of Salmonella Typhi isolates were MDR, compared to none of Salmonella Paratyphi A.
- Decreased ciprofloxacin susceptibility (DCS) was observed in 96.9% of Salmonella Typhi versus 11.5% of Salmonella Paratyphi A isolates.
Conclusions:
- Salmonella Paratyphi A is now the predominant cause of enteric fever in Phnom Penh, with rising ciprofloxacin resistance.
- Salmonella Typhi exhibited significantly higher rates of multidrug resistance and decreased ciprofloxacin susceptibility compared to Salmonella Paratyphi A.
- Azithromycin and ceftriaxone remained effective against all studied isolates.
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