Qazvin University of Medical Sciences
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Evaluation of mechanisms of colistin resistance in Klebsiella pneumoniae strains isolated from patients with urinary tract infection in ICU
Get PDFBackground and Objectives: One of the major causes of urinary tract infections is Klebsiella pneumoniae. Currently, few
studies investigated the mechanisms of resistance to colistin in Iran. The current study aimed to determine the prevalence of
plasmid and chromosome-mediated resistance to colistin in K. pneumoniae isolates.
Materials and Methods: 177 urine samples were collected from patients with urinary tract infections hospitalized in the
intensive care unit (ICU) of hospitals in the city of Qazvin. K. pneumoniae isolates were identified by standard biochemical
methods, resistance to colistin among K. pneumoniae isolates were tested by disk diffusion and microbroth dilution methods.
The chromosomal mutation and presence of the mcr genes in colistin-resistant K. pneumoniae were evaluated by PCR.
Results: Out of 177 samples, 65 K. pneumoniae were obtained from patients in the ICU. Six colistin-resistant isolates were
isolated with MIC values ≥4 μg/mL, none of them was positive for mcr1-5. In 4 isolates, missense mutation in mgrB gene
resulted in amino acid substitutions and in one isolate of mgrB gene was found intact mgrB gene.
Conclusion: The results suggest that mgrB mutation was the main mutation among colistin-resistant isolates and plasmid-borne colistin resistance was not expanded among strains
The Effect of Aqueous Extract of Saffron (Crocus sativus L. Stigma ) on the Behavior of Salmonella Typhimurium in A Food Model during Storage at Different Temperatures
Get PDFBackground: Given the concerns about the use of chemical preservatives in food,
the consumers and producers have been interested in natural alternatives, such as
plant essential oils and extracts. Since there are limited studies about the effect of
saffron
(Crocus sativus L.) on the behavior of foodborne pathogens in food models,
this study aimed to determine the inhibitory effect of aqueous extract of saffron
stigma on the growth behavior of Salmonella Typhimurium
(S. Typhimurium) in
commercial barley soup (as
a food model) during storage at different temperatures.
Method
s
: The minimum inhibitory concentration (MIC) and the minimum
bactericidal concentration (MBC) of the extract were determined against S.
Typhimurium using broth microdilution method. The growth of
S
. Typhimurium was
investigated in the presence of this extract in commercial barley soup during 12 days
of storage at 10, 20, and 30 °C. Results: The MIC and MBC values for saffron
extract against
S
. Typhimurium were 100 and >200 mg/m
l
, respectively. Also, the
saffron extract at
a concentration of 200 mg/ml and temperature of 10 °C had the
highest inhibitory effect on the growth of bacteria in commercial barley soup during
storage. Conclusion: According to the results of this study, the antimicrobial effect
of this extract increased in
a dose
-dependent manner against this bacterium.
Therefore, the use of proper concentrations of this extract together with appropriate
storage temperature can have an appropriate inhibitory effect on the growth of this
bacterium, improving food safety shelf life
Apical Microleakage Assessment of Calcium Silicate-based and Resin-based Sealers by Fluid Filtration Technique
Get PDFApplication of bacteriophage cocktails for reducing the bacterial load of nosocomial pathogens in hospital wastewater
Get PDFBackground and Objectives: In the third world and developing countries, hospital sewage is mixed with municipal wastewater. The treated effluent contains dangerous bacteria released into the environment and used in the irrigation of agricultural
products, and eventually these bacteria may endanger the human health through foods. Antibiotic-resistant bacteria are mostly found in hospital wastewater. In water and wastewater treatment plants, large amounts of toxic and polluting substances
are removed and destroyed, but this process does not eliminate bacteria.
Materials and Methods: Wastewater samples from 22 hospitals in Iran were collected and in the meantime specific phages
(against drug-resistant pathogenic bacteria) extracted using the bilayer agar technique. Phage amplification was performed
by employing a fermenter after phage identification. Amplified phages were added to the primary sedimentation pond using
New-Brunwick biofermenter BioFlo/Celligen®115 and the bacterial count was evaluated for the desired bacteria.
Results: Our phage cocktail was able to reduce 99.8%, 99.4%, 99.5%, 99.8%, 99.7%, 99.8%, 99.6% and 99.9% of E. coli, E.
faecium, E. faecalis, K. pneumoniae, A. baumannii, P. aeruginosa, S. maltophilia and S. aureus counts respectively.
Conclusion: The application of phage cocktails can remarkably help improve personal hygiene, the environment, and the
optimization of surface wate
