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Salmonellosis is a significant public health burden worldwide and being one of the most
common bacterial diarrheal illnesses among infants and young children (Wang et al 2017).
Qatar reports multiple incidences of salmonellosis outbreaks among the pediatric population
every year, coupled with a significant increase of multidrug-resistant (MDR) among gram-
negative bacteria including Salmonella in the last few years, resulting in a serious public
health hazard. Salmonella ranks among the four commonly isolated Enterobacteriaceae from
clinical samples at Hamad Medical Corporation (HMC). The identification of Salmonella
isolates into specific serovars is essential for epidemiologic studies, and tracing the source of
outbreaks (Hong et al., 2003) but it is laborious and time-consuming. Many genotyping
techniques, including pulsed-field gel electrophoresis (PFGE), random amplified polymorphic
DNA (RAPD), restriction fragment length polymorphism (RFLP), multiplex PCR and whole-
genome sequencing have been applied as alternative methods for Salmonella subtyping. Data
relevant to these typing methods are scarce in Qatar. The recurrent Salmonella outbreaks in
Qatar and the increasing number of salmonellosis cases (MOPH, Salmonella Work Shop, 2017,
Qatar) mandates more attention and efforts to hinder the spread of these bacteria. This
partially depends on the understanding of the bacterial phenotypic and genotypic
characteristics that influence its pathogenicity and transmission with the potential to cause an
outbreak.
BACKGROUND
OBJECTIVES
Conclusions
• Our results indicate a high antimicrobial resistance pattern of Salmonella,
which necessities the development of regulatory programs to combats
antimicrobial resistance.
• In particular, our results showed high resistance to Class (1) AMC cassette
that involves the transmission and expression of the resistance. This might
lead to a concern of increased multidrug resistance in the future.
• This study provides evidence guidance to activate and implement the pillars
of an antimicrobial stewardship program in animal and human health to
reduce MDR salmonellosis
References
Hong, Y., Liu, T., Hofacre, C., Maier,M., White, D.G., Ayers, S., et al.(2003). A restriction fragment length polymorphism-
based polymerase chain reaction as an alternative to serotyping for identifying Salmonella serotypes. Avian Dis. 47, 387–
395.doi:10.1637/0005-2086(2003)047[0387:ARFLPP]2.0.CO;2
Wong, M. H., Yan, M., Chan, E. W., Biao, K., and Chen, S. (2014). Emergence of clinical Salmonella enterica serovar
Typhimurium isolates with concurrent resistance to ciprofloxacin, ceftriaxone, and azithromycin. Antimicrob. Agents
Chemother. 58, 3752–3756. doi: 10.1128/AAC.02770-13
Acknowledgements
This work was supported by internal Grant no.: QUCG-BRC-19/20-1
This study aims to
• Characterize the phenotypic resistance profile of Salmonella to relevant antibiotics
among pediatrics population.
• Elucidate the molecular mechanisms underlying resistance to ceftriaxone, cefepime,
amoxicillin- clavulanate, tetracycline, trimethoprim-sulfamethoxazole, chloramphenicol,
colistin and azithromycin in Salmonella isolates identified from pediatric among 2 – 16
years old in Qatar.
•
• Characterize the 16S rRNA gene region by restriction fragment length polymorphism
(RFLP) to investigate if this region constitutes an appropriate ‘coincidental’ marker to
distinguish important pathogenic Salmonella species.
• Determine the lineages of Salmonella species and evolutionary relationships among
bacteria classified within the same genus.
1
Biomedical Research Center, Qatar University, P.O. Box 2713, Doha, Qatar.
2
Hamad Medical Corporation, Doha, Qatar.
Nahla O. Eltai
1
, Sara, H. Al-Hadidi
1
, Asmaa A Al Thani
1
,Sanjay H. Doiphode
2
and Hadi M. Yassine
1
Salmonellosis among Pediatric Population in Qatar: Prevalence,
Antibiotic Resistance and Molecular Epidemiology
Faculty and Postdoc, Medical,
Biomedical and Health Sciences
Methods
Phenotypic profile of
antibiotic
• 246 Salmonella isolates
were collected from
children under 16 years
old during Jan. 2018 -
Dec 2019, presented with
gastroenteritis at Hamad
Medical Corporation.
• Isolates were tested for
antibiotic susceptibility
against nineteen relevant
antibiotic using E-test.
Genotypic of AMR
• Isolates that harbor
antibiotic resistance were
confirmed using PCR
specific primers for 38
genes.
• In addition, the variable
region of class 1 and 2
integrons were studied by
PCR among amoxicillin-
clavulanate (AMC)
resistance samples.
Restriction fragment
length (RFLP )
• 16S rRNA PCR
amplicons were
enzymatically digested
with 7 restriction
enzymes including AluI,
BglI, BglII, EcoRI, SmaI,
HinfI& HaeIII according
to instructions of the
manufacturer.
Results
84
91
25
17
13
7
5
4
0
20
40
60
80
100
2 4 6 8 10 12 14 16
NO. OF ISOLATES
AGE OF CHILDREN IN YEARS
no. of salmonella isolates
Fig. 1 Relationship between Age of Children and
no. of Isolated Salmonella.
0
5
10
15
20
25
AMOX/CLA …
AMPICILLIN …
AZTREONAM
CEFEPIME
CEFTAZIDIUM
CEFTRIAXO…
ERTAPENEM
IMIPENEM
MEROPENE…
TAZOCIN …
TIGECYCLINE
TRIMETHOP…
CIPROFLOX…
LEVOFLOXA…
AZITHROMY…
FOSFOMYCI…
TETRACYCL…
CHLORAMP…
COLISTIN
19
21
3 3
4
4
0 0 0
3
2
13
8
3
4
0
24
11
20
Resistance %
Antibiotic
Fig. 2 Phenotypic Resistance Profile of Salmonella (246)
isolated from Children suffering from Gastroenteritis
Resistance was detected against 15 antibiotics. 38.2% of isolates
were resistant to at least one antibiotic. Overall, high resistance
was reported to tetracycline (23.9%), ampicillin (21.1%), AMC
(18.7%) and sulfamethoxazole-trimethoprim (13%). Further,
22.4% of the isolates were multidrug-resistant (MDR), with 4.1%
being ESBL producers.
In total 246 Salmonella were obtained, the
highest number was isolated from 2 years old
(34.2%) followed by (37%) from 3 & 4 years
while the lowest number of isolates (1.6%)
from 15 & 16 years old
A B
Fig.3: Dendrogram for RFLP-(16s rRNA region) Pattern among Salmonella
Isolated from Children with Gastroenteritis
Fig.2: Identification of Genes Encoding chloramphenicol Resistance (cat, cmlA
& floR) Isolated from Children Suffering from Gastroenteritis
M M
Lane M; 1 kb ladder marker, lane1: (cat), lane 2: (flo R), lane 3: (cat), lane 4: sample 75 (flo R),
lane 5: (flo R), lane 6: (cat) , lane 7: (cat, floR), lane 8: (floR) lane 9: (cml A), lane 10: (cat), lane
11: (cmlA), lane 12: (cat), lane 13: (cat), lane 14: (cmlA), lane 15: (floR), lane 16: (flor), lane 17:
(floR), lane 18: (floR), lane 19: (floR) , lane 20: (cat), lane 21: (floR), lane 22: (cmlA, floR), lane
23: (floR), lane 24: (floR) lane 25: (cat), lane 26: (cat), lane 27: sample 426 (cat)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
cmlA
cat
floR
RFLP analysis by scoring method (paired group algorithm- Jaccard similarity measure by using
Past software)
This dendrogram divided Salmonella isolates to 2 main group. The similarity between these
groups was 55%.
1000
500
Pb