Determination of carbapenem resistance mechanism in clinical isolates of Pseudomonas aeruginosa isolated from burn patients, in Tehran, Iran

Carbapenems are the most important therapeutic options that effect against serious infections caused by multidrug resistant Pseudomonas aeruginosa [MDR-PA] isolates. Carbapenems resistant isolates of P. aeruginosa are increasing worldwide. The aim of this study was to determine the carbapenem resistance mechanisms in clinical P. aeruginosa isolates from burn patients, in Tehran, Iran. A total of 53 non-duplicated isolates of carbapenem-resistant P. aeruginosa were collected from burn patients. The presence of carbapenemase genes were determined by PCR. AmpC overproducer isolates were detected by phenotypic method. The mutation and transcription level of oprD were determined by PCR-sequencing and quantitative Real-time PCR [RT-PCR], respectively. Twenty-seven [50.9%] isolates were positive for carbapenemase [bla[vm] = 25 and bla[mp] = 2] and showed high-level resistance to imipenem and merope-nem. Twenty-eight isolates were AmpC overproducers. All isolates had a mutation in the oprD gene and down-regulation of oprD was found in 56.6% of MDR-PA isolates. Although the presence of carbapenemase is the common mechanism of resistant to carbapenem, but carbapenem resistance was found by oprD mutation-driven and the AmpC overproducing isolates in Tehran, Iran

effects of berberine and palmatine on efflux pumps inhibition with different gene patterns in Pseudomonas aeruginosa isolated from burn infections

Background: Related Multidrug Resistance [MDR] to efflux pumps is a significant problem in treating infections caused by Pseudomonas aeruginosa [P. aeruginosa]. Plant compounds have been identified as Pump Inhibitors [EPIs]. In the current study, the potential effect of Berberine and Palmatine as EPIs were investigated on efflux pump inhibition through focusing on different gene patterns in P. aeruginosa isolated from burn infections

Methods: All isolates were collected and identified using the standard biochemical tests. Antimicrobial sensitivity was performed based on disk agar diffusion method for 12 antibiotics. MIC-MBC tests were also performed based on the broth microdilution method to detect synergistic relationship between ciprofloxacin, Berberine and Palmatine. Detection of mexA, mexB, mexC, mexD, mexE, mexF and mexX was conducted by PCR assay. Fisher's Exact test and Logistic Regression were used as statistical tools

Results: A total of 60 P. aeruginosa isolates were collected. The highest and lowest levels of resistance were found to be respectively against clindamycin and tigecycline. Comparing the MIC with MBC distribution, it was found that Berberine and Palmatine lower the MIC-MBC level of ciprofloxacin. The PCR results indicated that the highest frequency is about MexAB-OprM operon. The statistical analysis among different gene patterns of efflux pumps showed that there were no significant relationships between the effectiveness of Berberine and Palmatine [p>0.05]

Conclusion: It can be speculated that Berberine and Palmatine both act as EPIs and can be used as auxiliary treatments with the purpose of increasing the effect of available antibiotics as well as decreasing the emergence of MDR bacteria. The efficiency of these combinations should be studied further under in vivo conditions to have a more comprehensive conclusion regarding this issue

Molecular investigation of Staphylococcus aureus isolated from the patients, personnel, air and environment of an ICU in a hospital in Tehran

The aim of this study was to determine the prevalence and characteristics of Staphylococcus aureus isolates from the patients, staff, air and environments of an ICU in a hospital in Tehran. During this study, 37 S. aureus isolates were collected and analyzed via the spa typing method. Of the 37 S. aureus isolates, 35 [94%] were methicillin resistant [MRSA], 28 [76%] were identified as SCCmec types III or IIIA, four [10%] were identified as SCCmec types I or IA and three [8%] were identified a SCCmec type IV. All of the MRSA isolates were resistant to oxacillin and contained mecA. The isolates were all spa typed and found to comprise 11 spa types, including t7688, t7689, and t7789, which have not previously been reported. The spa type t7688 was isolated from the hands of two ICU personnel. The spa type t7689 was observed among five isolates from the air and the environment. The spa type t7789 was observed among three isolates from the patients, ventilators and the air. The majority of the isolates [43%] belonged to spa types t030 and t037. Our results revealed that MRSA strains that were isolated from the air, the environment of the ICU and the patients who were colonized or infected with MRSA often exhibited the same spa and SCCmec types. These results also reveal that the isolates from the patients and environment were usually indistinguishable

Antimicrobial effects of AH26 sealer/antibiotic combinations against Enterococcus faecalis

The purpose of this in vitro study was to evaluate the antimicrobial effects of two antibiotics added to AH26 sealer against Enterococcus faecalis [EF]. The antimicrobial effects of two antibiotic [amoxicillin and doxycycline] that were added separately to AH[26] sealer was evaluated by using the agar diffusion test and in vitro human root inoculation method. The freshly mixed sealers were placed in prepared wells inside agar plates inoculated with EF, and were incubated at 37°C. The zones of inhibition were measured at 24, 48, 72 hours and 7 days. Root specimens were prepared and obturated with lateral condensation technique. Samples were collected from infected root canals after 2 and 7 days of incubation and the number of colony-forming units [CFU] was determined. The data were analyzed using one-way and two-way ANOVA. The findings of this study revealed that sealer-antibiotic combination containing amoxicillin and doxycycline had a significant difference in the mean zones of inhibition when compared to AH[26] sealer alone in all of the time periods [P<0.05]. The minimum effective concentration against EF was one percent of sealer powder weight for both of amoxicillin and doxycyline. The mean log[10] CFU in AH[26]-doxycyline combination group was significantly lower than other groups at 48 h incubation period [P<0.05]. AH[26]-doxycycline combination group and AH26-Amoxicillin combination group killed bacteria [mean CFU=0] in the dentinal tubules at 7 days incubation period. In vitro root fillings carried out with gutta-percha and AH26-antibiotic combination were effective in killing EF in dentinal tubules

Emergence of high-level vancomycin-resistant Staphylococcus aureus in the Imam Khomeini hospital in Tehran

The objective of the study was to investigate the prevalence of vancomycin-resistant Staphylococcus aureus [VRSA]. Three hundred and fifty-six S. aureus isolates from the Imam Khomeini hospital in Tehran, Iran, were evaluated for methicillin and decreased vancomycin susceptibility by the microbroth dilution method. The mecA, vanAand vanB genes were targeted by polymerase chain reaction. Of the 356 isolates, 149 [41.85%] S. aureus strains were resistant to methicillin. Two strains of methicillin-resistant S. aureus were VRSA strains. One isolate, Teaching Hospital-1 [TEH-1], had a vancomycin minimum inhibitory concentration [MIC] of 64 micro g/ml and was susceptible to teicoplanin while the other isolate [TEH-2] had a vancomycin and teicoplanin MIC of 512 and > 256 mg/ml, respectively, and was positive for the vanA gene. This report shows that the emergence of VRSA in Iran warrants active microbiological surveillance and careful monitoring of vancomycin therapy