Impact of co-infections with enteric pathogens on children suffering from acute diarrhea in southwest China

Background:Acute diarrhea is a global health problem,resulting in high morbidity and mortality in children.It has been suggested that enteric pathogen co-infections play an important role in gastroenteritis,but most research efforts have only focused on a small range of species belonging to a few pathogen groups.This study aimed to assess the impact of co-infections with a broad range of enteric pathogens on children aged below five years who suffer from acute diarrhea in southwest China.Method:A total of 1020 subjects(850 diarrhea cases and 170 healthy controls)were selected from four sentinel hospitals in Kunming,Yunnan province,southwest China,from June 2014 to July 2015.Stool specimens were collected to detect five virus(rotavirus group A,RVA;norovirus,NoV;Sapovirus,SaV;astrovirus,As;and adenovirus,Ad),seven bacterial(diarrheagenic Escherichia coli,DEC;non-typhoidal Salmonella,NTS;Shigella spp.;Vibrio cholera;Vibrio parahaemolyticus;Aeromonas spp.;and Plesiomonas spp.),and three protozoan(Cryptosporidium spp.,Giardia lamblia,and Blastocystis hominis,B.hominis)species using standard microbiologic and molecular methods.Data were analyzed using the partial least square regression technique and chi-square test.Results:At least one enteric pathogen was detected in 46.7%(n=397)of acute gastroenteritis cases and 13.5%(n=23)of healthy controls(χ^(2)=64.4,P<0.05).Single infection with RVA was associated with acute diarrhea(26.5%vs.5.8%,P<0.05).The prevalence of a single infection with B.hominis in diarrhea cases was higher than in healthy controls(3.1%vs.0.5%,OR=4.7,95%CI:1.01–112.0).Single infection with NoV GII was not associated with diarrhea(4.4%vs.3.5%,OR=1.2,95%CI:0.5–3.3).Single infections with bacterial species were not observed.The prevalence of co-infections with two enteric pathogens in diarrhea cases was higher than in asymptomatic children(20.1%vs.5.3%,P<0.05).RVA-NoV GII was the most common co-infection in symptomatic children(4.4%),with it aggravating the severity of diarrhea.Conclusions:Although it is clear that RVA has an overwhelming impact on diarrhea illnesses in children,co-infection with other enteric pathogens appears to also aggravate diarrhea severity.These findings should serve as evidence for public health services when planning and developing intervention programs.

Antibiotic resistance and molecular characterization of diarrheagenic Escherichia coli and non-typhoidal Salmonella strains isolated from infections in Southwest China

Background:Bacterial diarrhea is one of the most common causes for medical consultations,mortality and morbidity in the world.Diarrheagenic Escherichia coli(DEC)and non-typhoidal Salmonella(NTS)are major intestinal pathogens in developing countries,and the indiscriminate use of antibiotics has greatly contributed to resistant strains.Hence,the aim of the present study is to identify the antimicrobial resistance patterns and the molecular characteristics of DEC and NTS in southwest,China.Methods:1121 diarrheal patients and 319 non-diarrheal subjects across all age groups were recruited from four sentinel hospitals from June 2014 to July 2015 in Kunming City,Yunnan Province.Each stool specimen was collected to detect DEC and NTS with standard microbiological and molecular methods.Antimicrobial resistance testing was performed with the Kirby-Bauer disk diffusion method,and the standards for antimicrobial susceptibility testing complied with the Clinical and Laboratory Standards Institute(CLSI).Molecular characterization of strains was carried out using pulsed-field gel electrophoresis(PFGE).A structured questionnaire was used to record basic epidemiological data(e.g.sex,age,residence,season,etc.).Data were analyzed using Chi-square or Fisher’s exact test.Results:DEC was detected in 127(11.33%)diarrhea cases and 9(2.82%)non-diarrheal cases(χ^(2)=20.69,P<0.001,OR=4.36,95%CI:2.19-8.65),and the prevalence of NTS isolated from diarrhea cases was higher than that of non-diarrheal cases across all age groups(n=42,3.75%,n=1,0.31%,χ^(2)=10.10,P=0.002,OR=12.38,95%CI:1.70-90.29).The rates of resistance to ten antibiotics of DEC and NTS showed significant differences(χ^(2)=386.77,P<0.001;χ^(2)=191.16,P<0.001).The rates of resistance to Amoxicillin and Clavulafiate(AMC),Cephalothin(CEP),Gentamicin(GEN)and Sulfamethoxazole-Trimethoprim(SXT)of DEC isolated from diarrhea cases were higher than those of NTS isolated from diarrhea patients(37.01%vs 14.29%,χ^(2)=7.57,P=0.006;29.92%vs 11.90%,χ^(2)=5.40,P=0.02;37.01%vs 11.90%,χ^(2)=5.80,P=0.016;62.20%vs 26.19%,χ^(2)=16.44,P<0.001;respectively).Ciprofloxacin(CIP)was the most sensitive antibiotic for DEC and NTS strains isolated from diarrhea cases.Resistance rates of DEC isolates from cases and controls to more than three kinds antimicrobials(multidrug resistance,MDR)showed no significant differences(81.10%vs 88.89%,P=0.33).Pulsotype patterns of DEC strains were highly diverse;however,the pulsotype pattern of NTS strains was closely related to the serotype.The pattern of S.enteritidis was highly similar,but the S.enterica Typhimurium strain was discrete.Conclusions:Antibiotic resistance of Enterobacteriaceae is of great concern.The societal effects of antibiotic use justify strict monitoring to combat increases in antimicrobial resistance.Molecular epidemiology and systematic epidemiological investigation can provide accurate evidence for tracking the infection source.

Positive effect of spring advance on the diet quality of an alpine herbivore

Changes in vegetation phenology related to global warming are having alarming effects on the life history traits of many herbivore species.Such changes are particularly critical in alpine ecosystems,where strong climate limitations on plant growth make seasonal synchronization imperative for the growth,reproduction and survival of herbivores.However,despite the pivotal role of resource-use strategies on the performances of such species,few studies have explicitly assessed the mechanistic impact of climate change on their diets.We aimed to fill this gap by studying the effect of spring onset on the dietary composition and quality of a medium-size alpine herbivore while considering density-dependent processes and age-and sex-specific differences in foraging behavior.Using an exceptional,long-term(24 years)direct individual-based dietary monitoring of a Pyrenean chamois population(Rupicapra pyrenaica pyrenaica),we showed that ongoing earlier onsets of spring are leading to an earlier access to high-quality forage and therefore a higher diet quality at a fixed date,without apparent changes in diet composition.We also showed that at high densities,intraspecific competition reduced diet quality by driving animals to feed more on woody plants and less on nutritious forbs and graminoids.By assessing the mechanistic effects of global warming on the dietary patterns of species at the center of trophic networks,this study is an essential step for predictive models aiming at understanding the ongoing ecosystem consequences of the global climatic crisis.

Early life investment in antlers and body growth reflects adult performance in roe deer population under supplementary feeding conditions

Recent research has challenged the idea that cervid antlers are such costly traits,supporting the assertion early-life antler investment is an honest signal of adult phenotypic quality.However,inferences were made based on antler measurements while growing(velvet)and thus,studies on fully-formed clean antlers are needed to avoid possible bias caused by the inter-individual variation in antler growth phenology.We studied a semi-captive population of European roe deer inhabiting a sub-Mediterranean area(Valsemana research station)and living under optimal conditions(ad libitum food supply and veterinary care).Based on repeated measurements taken from 146 individuals,we assessed whether allocation to secondary sexual traits during early life affected body mass or antler development during adulthood.Furthermore,we evaluated which body measurements better predicted future male quality.Additionally,using 488 individuals,we described age-class-specific variation in male body measurements and assessed the decline in antler size between adult and senescent stages(i.e.magnitude of senescence).Results agree with the assertion that there is no negative effect of a high investment in antler during early life on adult antler size or body mass,but we suggest the use of clean antlers as a more robust and reliable measure.The variables that better predicted body mass during adulthood were yearling body mass and body size at 6 months.Antler score between 10 and 18 months resulted in the best indicator of adult antler size.Finally,we support the idea that the magnitude of senescence in antler size is smaller in environments with higher resource availability during winter.