scholarly journals A Modified Selective Medium Containing Benzalkonium Chloride (BKC) for the Isolation of <i>Pseudomonas aeruginosa</i>from Raw Milk

2012 ◽  
Vol 03 (07) ◽  
pp. 947-950 ◽  
Author(s):  
Aylin Akoglu ◽  
Evrim Gunes Altuntas ◽  
Gokce Polat Yemis
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Benzalkonium Chloride ◽  
Raw Milk ◽  
Selective Medium

scholarly journals Effect of subinhibitory concentrations of benzalkonium chloride on the competitiveness of Pseudomonas aeruginosa grown in continuous culture

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Paul H. Mc Cay ◽  
Alain A. Ocampo-Sosa ◽  
Gerard T. A. Fleming
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Continuous Culture ◽  
Benzalkonium Chloride ◽  
Efflux Pump ◽  
Fold Increase ◽  
Original Strain ◽  
Limiting Nutrient ◽  
Continuous Culture System ◽  
Subinhibitory Concentrations ◽  
Limited Culture

This study investigates the link between adaptation to biocides and antibiotics in Pseudomonas aeruginosa. An enrichment continuous culture of P. aeruginosa NCIMB 10421 (MIC 25 mg BKC l−1) was operated (D=0.04 h−1, 792 h) with added benzalkonium chloride (BKC). A derivative, PA-29 (696 h), demonstrated a >12-fold decrease in sensitivity to the biocide (MIC >350 mg BKC l−1). The variant demonstrated a 256-fold increase in resistance to ciprofloxacin, with a mutation in the gyrA gene (Thr-83→Ile). Similarly, culturing of the original strain in a continuous-culture system with ciprofloxacin selection pressure led to the evolution of BKC-adapted populations (MIC 100 mg BKC l−1). Efflux pump activity predominantly contributed to the developed phenotype of PA-29. An amino acid substitution (Val-51→Ala) in nfxB, the Mex efflux system regulator gene, was observed for PA-29. Overexpression of both MexAB-OprM and MexCD-OprJ was recorded for PA-29. Similarly, mexR, a repressor of the Mex system, was downregulated. Competition studies were carried out in continuous culture between PA-29 and the original strain (in the presence of subinhibitory concentrations of BKC). The outcome of competition was influenced by the concentration of biocide used and the nature of limiting nutrient. The inclusion of 1 mg BKC l−1 in the medium feed was sufficient to select (S=0.011) for the BKC-adapted strain in magnesium-limited culture. Conversely, the presence of 10 mg BKC l−1 in the medium supply was insufficient to select for the same organism (S=−0.017) in the glucose-limited culture. These results indicate the importance of environmental conditions on selection and maintenance of biocide adaptation.

scholarly journals Application strategies by selective medium treated with entomopathogenic bacteria Serratia marcescens and Pseudomonas aeruginosa as potential biocontrol against Coptotermes curvignathus

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Kit Ling Chin ◽  
Paik San H'ng ◽  
Chuan Li Lee ◽  
Wan Zhen Wong ◽  
Wen Ze Go ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mortality Rate ◽  
Serratia Marcescens ◽  
Selective Medium ◽  
Subterranean Termite ◽  
High Toxicity ◽  
Entomopathogenic Bacteria ◽  
Long Period ◽  
Behaviour Changes ◽  
Wood Consumption

The success of microbial termiticides in controlling termites depends on the ability of microbes to grow in different media and the functionality of the microbes as a resistant barrier or toxic bait. This study was conducted to understand the mortality rate and behaviour changes of the subterranean termite Coptotermes curvignathus Holmgren introduced with different concentrations of Serratia marcescens strain LGMS 1 and Pseudomonas aeruginosa strain LGMS 3 using wood and soil as bacterial transfer medium. In general, higher concentration of bacteria in soil caused a reduction in tunnelling activity and wood consumption and an increase in mortality. However, application on wood revealed a different outcome. Wood treated with S. marcescens of 10 6 CFU ml −1 concentration proved to be more efficient as bait than higher concentration applications as it caused a high mortality rate while still highly palatable for termites. Wood or soil treated with S. marcescens concentration higher than 10 9 CFU ml −1 creates a high toxicity and repellent barrier for termites. Pseudomonas aeruginosa of 10 9 CFU ml −1 concentrations applied on wood served as a slow-acting toxic bait. However, the ability for S. marcescens and P. aeruginosa to survive on wood is low, which made the bait unable to retain a useful level of toxicity for a long period of time and frequent reapplication is needed.

scholarly journals Prevalence of Resistance Genes to Biocides in Antibiotic-Resistant Pseudomonas Aeruginosa Clinical Isolates

2021 ◽  
Author(s):  
Farzad Khademi ◽  
Shahram Habibzadeh ◽  
Hamid Vaez ◽  
Mohsen Arzanlou ◽  
Somayeh Safarirad ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Resistance Genes ◽  
Benzalkonium Chloride ◽  
Resistance Rate ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Chlorhexidine Digluconate ◽  
Biocide Resistance

Abstract Background: Biocides are frequently used as preservative, disinfectant and sterilizer against many microorganisms in hospitals, industry and home. However, the resistance rate of Pseudomonas aeruginosa (P. aeruginosa) strains to biocides is increasing. The aim of this study was to evaluate the antimicrobial activity of four frequently used biocides against P. aeruginosa and to determine the prevalence of genes involved in biocide resistance. Methods: A total of 76 clinical isolates of P. aeruginosa strains were used in the present study. The minimum inhibitory concentrations (MICs) of four biocides, i.e. chlorhexidine digluconate, benzalkonium chloride, triclosan and formaldehyde, against P. aeruginosa strains were determined using agar dilution method. In addition, the prevalence of biocide resistance genes was determined using the polymerase chain reaction (PCR) method.Results: In the present study, the highest MIC90 value was observed for benzalkonium chloride (MIC90=1024 μg/mL), followed by formaldehyde (MIC90=512 μg/mL), triclosan (MIC90=512 μg/mL) and chlorhexidine digluconate (MIC90=64 μg/mL). Furthermore, the prevalence of qacEΔ1, qacE, qacG, fabV, cepA and fabI genes were 73.7% (n=56), 26.3% (n=20), 11.8% (n=9), 84.2% (n=64), 81.5% (n=62) and 0% (n=0), respectively. A significant association was observed between the presence of biocide resistance genes and MICs (p<0.05). Furthermore, there was no significant association between the presence of biocide resistance genes and antibiotic resistance (p>0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p<0.05). Conclusion: Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals. However, we recommend continuous monitoring of the antimicrobial activity of biocides and the prevalence of biocide-associated resistance genes for a better prevention of microorganism dissemination and infection control in hospitals.

scholarly journals Isolation and Identification of Listeria Monocytogenes in Bangalore City from Various Food Samples

2021 ◽  
Vol 14 (4) ◽  
pp. 2271-2276
Author(s):  
Vedavati Goudar ◽  
Kanthesh B M ◽  
Nagalambika Prasad
Keyword(s):  
Listeria Monocytogenes ◽  
Ice Cream ◽  
Raw Milk ◽  
Food Samples ◽  
Selective Medium ◽  
Chicken Meat ◽  
Isolation And Identification ◽  
Fresh Milk ◽  
Biochemical Identification ◽  
Raw Fish

The current research emphasis on the isolation and differentiation of Listeria monocytogenes from different food samples most frequently infected with Listeriosis outbreaks. Crude chicken meat, raw milk, pasteurized cheese, ice cream and raw fish are samples from the city of Bangalore. The selective medium mainly used for the isolation of Listeria is oxford agar. Using isolated L. monocytogenes from food samples, morphologic and biochemical identification was carried out. 2 samples (fresh milk and Ice cream) were positive out of 5 samples; 3 samples (raw chicken meat, raw fish, and pasteurized cheese) were negative. The results conferred during this study indicate the contamination of Ice- cream and Raw Milk samples with L. monocytogenes.

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