salmonellosis due to nontyphoidal salmonella ( nts ) infection is a global public health concern , particularly in salmonella endemic low and middle income countries ( lmics ) .
treatment is critical for persons with severe disease , particularly children and immune compromised people .
treatment with an appropriate antibiotic can shorten the duration of symptoms , significantly reduce severity of disease and the risk of transmission , and prevent potentially lethal complications .
emergence of resistance to first - line therapy like ampicillin , chloramphenicol , and cotrimoxazole including ciprofloxacin among salmonella spp . during the last decades
has complicated the situation [ 1 , 2 ] . for treatment of salmonella infection resistant to these drugs , extended - spectrum cephalosporins ( escs )
are considered as an alternative therapeutic choice . with the increased use of -lactam antibiotics to treat enteric infection , salmonella spp .
had acquired resistant to third generation cephalosporin antibiotics in different parts of the world and had been associated with clinical treatment failure [ 3 , 4 ] .
extended - spectrum beta - lactamases ( esbl ) are usually encoded by large plasmids ( 100  kb ) that are transferable from strain to strain and between bacterial species [ 57 ] .
resistance to escs is mediated primarily by production of class a esbls , which can hydrolyze oxyimino cephalosporins but are not active against cephamycins and carbapenems .
the plasmid - encoded ctx - m type esbls production was initially identified in 1983 in germany .
the ctx - m family enzymes , which confer high levels of resistance to escs , have similar substrate specificities and inhibitor profiles to tem .
the ctx - m type esbls have been reported to be found worldwide in different members of enterobacteriaceae isolated from human and other animal sources .
earlier we have reported the emergence of blactx - m and blatem type esbl producer s. typhi in one - year - old child with recurrent high - grade fever . in recent years
there have been several reports indicating the emergence of resistance to -lactam antibiotics among salmonella species . here , we present blatem gene mediated esbl production among salmonella spp
. isolated from stool specimen of patients with diarrhea in an urban setting of bangladesh .
as part of a microbiological analysis of stool sample received at dhaka treatment centre of international centre for diarrheal diseases research , bangladesh ( icddr , b ) during 20052013 , we have analyzed 128,312 fecal specimen following standard microbiological method to identify salmonella spp .
the putative extended - spectrum beta - lactamase ( esbl ) producing strains were tested by the double - disc synergy method and detection of -lactamase genes ( blactx - m , blatem , blashv , and blaoxa genes ) was performed by pcr as describe elsewhere .
overall , the annual incidence of salmonella infection showed a decreasing trend and the proportion came down significantly from 2% in 2005 to 1.0% in 2013 ( p < 0.001 ) .
( 2120 , [ 1.7% ] ) , nontyphoidal salmonella ( nts ) isolates were more frequently isolated than typhoidal salmonella ( ts ) ( 72.8% versus 27.2% , p < 0.001 ) .
demographic information showed that salmonellae were isolated from patients of all age groups with a maiden age of 4.04 years .
of the total salmonella positive patients , 51.2% ( n = 1086 ) were children aged less than five years . among the ts serogroups ,
s. typhi was predominant ( 404 , [ 65.1% ] ) followed by s. paratyphi b ( 139 , [ 22.4% ] ) and s. paratyphi a ( 78 , [ 12.6% ] ) .
of the nts isolates , serogroups c1 strains were more frequently isolated ( 560 , [ 37.4% ] ) , followed by b ( 203 , [ 13.5% ] ) , c2 ( 203 , [ 13.5% ] ) , e ( 127 , [ 8.5% ] ) , d ( 94 , [ 6.3% ] ) , g ( 79 , [ 5.3% ] ) , nontypeable salmonella ( 54 , [ 3.6% ] ) , s. typhimurium ( 2 , [ 0.1% ] ) , and a ( 1 , [ 0.06% ] ) serogroup .
the yearly distribution of salmonella spp . showed distinct seasonality with higher isolation during may to october in each year .
temporal shift was noted in the prevalence of serogroups , seasonality , gender distribution , and resistance pattern between ts and nts isolates .
around 40% of the salmonella isolates showed resistance to nalidixic acid ( na ) followed by 36% to ampicillin ( amp ) , 20% to cotrimoxazole ( sxt ) , 4% to ciprofloxacin ( cip ) , 13% to chloramphenicol ( c ) , and 4% to ceftriaxone ( cro ) .
resistance to 3 antibiotic classes was more common among ts strains than nts counterpart ( 36.6% versus 19.8% , p < 0.001 ) . among the representative salmonella
isolates with unusual resistant phenotype ( ampccipcronasxt ) , first identified in 2011 , blatem gene was detected in 88% ( 7/8 ) of the strains ( figure 1 ) .
interestingly , one s. typhi was positive for both blatem and blactx - m genes which is a very rare phenomenon . in our earlier report , we noticed that this same phenomenon was observed in one s. typhi isolated from blood of a typhoid patient .
these findings suggest that multi - esbl producer strains are circulating in bangladesh . however , to the best of our knowledge , this is the first report of esbl production among salmonella isolated from stool specimen of diarrheal patients in urban dhaka , bangladesh .
detailed molecular characterization including sequencing is necessary for further geno- and subtyping of these strains .
the study finding reflects the higher prevalence of mar salmonella spp . among children aged < 5 years and
blatem gene mediated esbl production among salmonella spp . isolated from stool sample of diarrheal patient in urban bangladesh .
therefore , it is important to establish a surveillance program to understand actual disease burden due to salmonella as well as promote specific and actual line of therapy for salmonellosis .
 salmonellosis , an acute invasive enteric infection , is endemic in bangladesh . 
 we analyzed 128,312 stool samples of diarrheal patients to identify salmonella spp . during 20052013 . 
 a total of 2120 ( 1.7% ) salmonella spp . were isolated and the prevalence of salmonella spp . 
 decreased significantly over time ( 21% , p < 0.001 ) . among the typhoidal salmonella ( ts ) 
 serogroups , s. typhi was predominant ( 404 , [ 65.1% ] ) followed by s. paratyphi b ( 139 , [ 22.4% ] ) and s. paratyphi a ( 78 , [ 12.6% ] ) . of the nontyphoidal salmonella ( nts ) 
 isolates , the serogroup c1 ( 560 , [ 37% ] ) was predominant followed by b ( 379 , [ 25% ] ) , c2 ( 203 , [ 14% ] ) , e ( 127 , [ 9% ] ) , and d ( 94 , [ 6% ] ) . 
 most of the resistance was found towards nalidixic acid ( 40% ) , ampicillin ( 36% ) , cotrimoxazole ( 20% ) , chloramphenicol ( 13% ) , ciprofloxacin ( 4% ) , and ceftriaxone ( 4% ) . 
 interestingly , 32% of the isolates showed reduced susceptibility to cip . 
 multiantibiotic resistance ( mar , 3 drugs ) was more common among ts than nts strains ( p < 0.001 ) . among the representative 
 ceftriaxone - resistant isolates , blatem gene was detected among 88% ( 7/8 ) of the strains , whereas only one strain of s. typhi was positive for both blatem and blactx - m genes . 
 the study reflects higher prevalence of mar salmonella spp . and 
 is the first to report the blatem gene mediated esbl production among salmonellae in bangladesh . 
 emergence of mar salmonella spp . 
 in particular esbl strains should be considered a public health concern . 
1. Introduction
2. Material and Methods
3. Result and Discussion
4. Conclusion