Investigating Biofilm Formation and Antibiofilm Activity Using Real Time Cell Analysis Method in Carbapenem Resistant Acinetobacter baumannii Strains.

Acinetobacter baumannii is a significant nosocomial pathogen, with its biofilm forming capacity playing an important role in its pathogenicity. The fast and reliable detection of the biofilm formation and measurement of antibiofilm activity of various molecules are critical for combating A. baumannii infections. In this study, we aimed to detect biofilm formation by real time cell analyses (RTCA) method in clinical A. baumannii isolates and to investigate antibiofilm activities of tigecycline (TGC), N-acetylcysteine (NAC), and acetylsalicylic acid (ASA). The effect of the tested drugs on expressions of biofilm-related genes bap and csuE in clinical A. baumannii strains was also analyzed by real time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Biofilm forming capacities for strong and weak biofilm producer A. baumannii strains were detected within 10 h by RTCA method (P < 0.05). We also observed that sub-minimum inhibitory concentrations of NAC + TGC and ASA + TGC combinations could significantly reduce biofilm formation and expression of biofilm-related genes in A. baumanii strains. No statistically significant activity of the tested drugs was detected against mature biofilms of the bacterial strains with the RTCA method. These results suggest that reproducible results on biofilm production capacity of A. baumannii strains and antibiofilm activities of various compounds can be obtained in a short time using RTCA method. Therefore, RTCA method seems to be a beneficial technique for biofilm detection and can help in combating A. baumannii infections by giving health providers the opportunity of implementing antibiofilm treatment strategies in a timely manner.

Silencing acpP gene via antisense oligonucleotide-niosome complex in clinical Pseudomonas aeruginosa isolates.

Pseudomonas aeruginosa, an opportunistic Gram-negative pathogen, is one of the major causes of nosocomial infections. In addition to its physiological adaptation capacity, it can develop resistance to disinfectants and antibiotics through various mechanisms. Recently, new eradication methods are gaining attention. Therefore, in this study, an LNA-2'-O-methyl hybrid antisense oligonucleotide targeting the acyl carrier protein P (acpP) gene was introduced into P. aeruginosa isolates. The design was determined through sequence analysis and prediction of the secondary structure of mRNA by software. Niosomes were used for enhancing cellular uptake. The control of the binding and transfection ability of the sequence was determined fluorometrically by labeling with 6-Fam. The effects were determined with broth microdilution method and qPCR studies. Eight different formulations were prepared. Among these, one formulation has shown to have ASO complexation ability whose composition was 312 µl Span 80 + 69.5 mg Cholesterol+ 36.4 mg CTAB+1 ml Chloroform and 5 ml dH2O. Thus this formulation was determined as the delivery system for the next stages. Significant gene inhibition was detected at the six isolates. Results of this study suggested that niosomes can be used as a delivery system for cellular uptake of ASO and could eliminate bacterial growth.

Antifungal and Antibiofilm Activities of Selective Serotonin Reuptake Inhibitors Alone and in Combination with Fluconazole.

OBJECTIVES: Candida spp. are clinically important pathogens that cause difficulties for treatment by biofilm formation. Considering antifungal resistance rates and the limitations in the discovery of new antifungals, the antifungal and antibiofilm effects of various drugs used for different therapeutic purposes are becoming more important. The goal of our study was to determine the antifungal and antibiofilm effects of the selective serotonin reuptake inhibitors (SSRIs), namely sertraline (SRT), paroxetine (PRX), and fluoxetine (FLX) alone and in combination with fluconazole (FLC) against Candida spp. MATERIALS AND METHODS: Twenty Candida spp. strains isolated from clinical samples from Ege University Hospital were identified by the Dalmau method and matrix-assisted laser desorption ionization time of flight mass spectrometry. The minimum inhibitory concentrations (MICs) of the SSRIs and FLC were detected by broth microdilution method. Synergistic interactions between the SSRIs and FLC were investigated by checkerboard assay. The antibiofilm effects of the SSRIs were determined by spectrophotometric microplate method. RESULTS: Among the isolates, five different Candida spp. (C. albicans, C. glabrata, C. krusei, C. tropicalis, and C.parapsilosis) were identified. The MICs of the SSRIs ranged between 16-512 µg/mL. While SRT showed the highest antifungal effect, the antibiofilm efficacy of FLX was higher than that of the other agents. Moreover, FLX and PRX showed a synergistic effect with FLC in 13 and 19 isolates, respectively. Four isolates were strong biofilm producers while nine isolates were moderate biofilm producers. C. parapsilosis strains showed higher biofilm production than the other species. At MIC/2 concentration, FLX and SRT alone inhibited mature biofilms in six and five isolates, respectively, while PRX caused increases biofilm formation in seven isolates. CONCLUSION: This study revealed that MIC/2 concentrations of SSRIs could have antifungal and antibiofilm effects. SRT and FLX alone or in combination with antifungals may possibly have therapeutic potential for combating fungal infections.

In vitro effects of ciprofloxacin, levofloxacin and moxifloxacin on Mycobacterium tuberculosis isolates.

INTRODUCTION: Increased tuberculosis prevalence, and isolation of multidrug resistant (MDR) Mycobacterium tuberculosis strains frequently as causative organisms from tuberculosis infections are resulted in increasing need of new anti-tuberculosis drugs. Nowadays, fluoroquinolones known to have fewer side effects than the other drugs used in treatment of tuberculosis are sometimes assessed even as first-line anti-tuberculosis drugs due to their in vitro and in vivo strong activity. It was aimed in this study to investigate phenotypically the fluoroquinolone susceptibility in MDR and non-MDR M. tuberculosis isolates. MATERIALS AND METHODS: A total of 126 MDR and non-MDR M. tuberculosis isolates from mycobacteriology laboratory of two hospitals in the Aegean Region of Turkey were included in the study. Ciprofloxacin (CIP), levofloxacin (LEV) and moxifloxacin (MXF) susceptibilities were assessed by agar proportion method according to the Clinical and Laboratory Standards Institute (CLSI) recommendations. RESULT: Twelve (15.2%), 5 (6.3%) and 4 (5.1%) of the MDR M. tuberculosis strains were resistant to CIP, LEV, MXF, respectively [resistance breakpoints (µg/mL); CIP (> 2), LEV (> 1), MXF (> 0.5)] while non-MDR strains were susceptible to CIP, LEV, MXF. CONCLUSIONS: Consequently, although high fluoroquinolone susceptibilities were evaluated as a pleasing data in this study, to preserve their efficiency for many years steadily, quinolone usage and resistance increment in MDR M. tuberculosis isolates should be monitored elaborately.

Investigation of class-d beta-lactamases causing carbapenem resistance in clinical Acinetobacter baumannii isolates

Background/aim: Acinetobacter baumannii is an important causative agent of nosocomial infections, and carbapenems have been frequently used in the treatment of these infections. This study was designed to investigate the prevalence of primary carbapenem hydrolyzing oxacillinase (CHO) types in clinical A. bumannii strains. Materials and methods: Minimum inhibitory concentration (MIC) values of 76 imipenem nonsusceptible A. baumannii strains, isolated from a tertiary care hospital, were determined by microdilution method. The clonal relationship of the isolates was analyzed with enterobacterial repetitive intergenic consensus (ERIC)-PCR, and the presence of CHO major groups (OXA-23; OXA-24, OXA-51, and OXA-58 groups) was investigated with multiplex PCR. Results: According to the ERIC-PCR patterns, the isolates were distributed in 13 different clones, the largest of which had 40 members. blaOXA-51-group was detected in representatives of all clones, whereas blaOXA-23-group was detected in representatives of all but two small clones. Additionally, the presence of blaOXA-58-group was discovered in the members of two small clones, whereas blaOXA-24-group was not encountered in any of the examined strains. Conclusion: Molecular fingerprinting revealed that most imipenem-resistant A. baumannii strains were clonally related. blaOXA-23-group and blaOXA-51-group were mostly responsible for the imipenem resistance of the examined A. baumannii strains.

[Comparison of phenotypic methods and polymerase chain reaction for the detection of carbapenemase production in clinical Klebsiella pneumoniae isolates]. / Klinik Klebsiella pneumoniae izolatlarinda karbapenemaz üretiminin saptanmasinda polimeraz zincir reaksiyonu ve fenotipik yöntemlerin karsilastirilmasi.

Being a member of the Enterobacteriaceae family, Klebsiella pneumoniae is an opportunistic pathogen that inhabits normal human microbiota and causes predominantly hospital-acquired infections. The emergence of K.pneumoniae isolates which are resistant particularly to the carbapenem group of antibiotics has led to an increase in hospitalization period, mortality and morbidity. Although different rates of resistance are observed between countries, regions and even healthcare facilities, there has been a rapid increase in the prevalence of carbapenem-resistant strains in the last 10 years. Fast and correct identification of carbapenem-resistant strains is important for the successful treatment of infections caused by these resistant bacteria. The objective of this study was to investigate the presence and the types of carbapenemases in carbapenem-resistant K.pneumoniae strains using "MASTDISCS™ ID carbapenemase detection disc set", a commercial product that can be used for this purpose, and "Carbapenem Inactivation Method (CIM)", a relatively new method, and compare the results of these methods by polymerase chain reaction (PCR). For this purpose, we used 54 K.pneumoniae strains isolated in 2015-2016, that were resistant to any of the ertapenem, meropenem or imipenem antibiotics. The identification of the strains was performed using VITEK MS and their antibiotic susceptibility tests were carried out using the VITEK 2 Compact® automated system. For the strains that were found resistant to carbapenems in the automated system, the minimum inhibitor concentration (MIC) values were determined by the gradient testing method according to the recommendations of "The European Committee on Antimicrobial Susceptibility Testing (EUCAST)". The blaOXA-48, blaIMP, blaNDM, blaVIM, and blaSIM genes were investigated with PCR among these isolates. Phenotypic enzyme typing was performed in the carbapenem-resistant strains using the "MASTDISCS™ ID carbapenemase detection disc set" and "Carbapenem Inactivation Method (CIM)". REP-PCR was used to reveal clonal relationship of the isolates. The 54 K.pneumoniae isolates were found as resistant to carbapenem and the MIC50 and MIC90 values of imipenem, meropenem and ertapenem were 32 µg/ml. Only 33 of the strains had blaOXA-48 and two of them had only blaNDM, the remaining 19 strains had both of these two genes. The blaIMP, blaVIM and blaSIM genes were not encountered in any of the isolates. When the isolates were assessed by the REP-PCR method, six main clones were detected. The "MASTDISCS™ ID carbapenemase detection disc set" was able to detect all the carbapenemase producing strains and it remained incapable of distinguishing OXA-48 in the strains which had both OXA-48 and metallo beta lactamase (MBL) enzymes. The CIM method showed a low rate of positivity (46.15%) in the strains containing blaOXA-48, but was found much more successful in the strains containing blaNDM with a detection rate of 85.71%. In this study, it was concluded that the Mastdiscs-ID method could be successfully used to detect the presence of blaOXA-48 which has a high prevalence in our country.

Mucoadhesive in situ gel formulation for vaginal delivery of clotrimazole: formulation, preparation, and in vitro/in vivo evaluation.

The purpose of this study was to develop a suitable mucoadhesive in situ gel formulation of clotrimazole (CLO) for the treatment of vaginal candidiasis. For this aim, the mixture of poloxamer (PLX) 407 and 188 were used to prepare in situ gels. Hydroxypropyl methylcellulose (HPMC) K100M or E50 was added to in situ gels in 0.5% ratio to improve the mucoadhesive and mechanical properties of formulations and to prolong the residence time in vaginal cavity. After the preparation of mucoadhesive in situ gels; gelation temperature/time, viscosity, mechanical, mucoadhesive, syringeability, spreadibility and rheological properties, in vitro release behavior, and anticandidal activities were determined. Moreover vaginal retention of mucoadhesive in situ gels was investigated with in vivo distribution studies in rats. Based on the obtained results, it was found that gels prepared with 20% PLX 407, 10% PLX 188 and 0.5% HPMC K100M/E50 might be suitable for vaginal administration of CLO. In addition, the results of in vivo distribution studies showed that gel formulations remained on the vaginal mucosa even 24 h after application. In conclusion, the mucoadhesive in situ gels of CLO would be alternative candidate for treatment of vaginal candidiasis since it has suitable gel properties with good vaginal retention.

Analyses of Plasmids Harbouring Quinolone Resistance Determinants in Enterobacteriaceae Members.

The aim of this study was to explore the plasmid characteristics of eight clinical Enterobacteriaceae strains containing extended broad spectrum beta-lactamases and plasmid-mediated quinolone resistance. Plasmids were transferred by conjugation or transformation and resistance determinants were investigated by PCR. We showed that at least one plasmid harbouring qnrB or qnrS determinant was transferred by conjugation in five isolates. QepA determinant was confirmed to be on a non-conjugative plasmid. We found at least one beta-lactamase gene in seven of the eight clinical isolates having plasmid-mediated quinolone resistance, which indicated that these two resistance determinants were mostly on the same conjugative plasmids.

Development, characterization, and in vivo assessment of mucoadhesive nanoparticles containing fluconazole for the local treatment of oral candidiasis.

This study aimed to develop a suitable buccal mucoadhesive nanoparticle (NP) formulation containing fluconazole for the local treatment of oral candidiasis. The suitability of the prepared formulations was assessed by means of particle size (PS), polydispersity index, and zeta potential measurements, morphology analysis, mucoadhesion studies, drug entrapment efficiency (EE), in vitro drug release, and stability studies. Based on the optimum NP formulation, ex vivo drug diffusion and in vitro cytotoxicity studies were performed. Besides, evaluation of the antifungal effect of the optimum formulation was evaluated using agar diffusion method, fungicidal activity-related in vitro release study, and time-dependent fungicidal activity. The effect of the optimum NP formulation on the healing of oral candidiasis was investigated in an animal model, which was employed for the first time in this study. The zeta potential, mucoadhesion, and in vitro drug release studies of various NP formulations revealed that chitosan-coated NP formulation containing EUDRAGIT(®) RS 2.5% had superior properties than other formulations. Concerning the stability study of the selected formulation, the formulation was found to be stable for 6 months. During the ex vivo drug diffusion study, no drug was found in receptor phase, and this is an indication of local effect. The in vitro antifungal activity studies showed the in vitro efficacy of the NP against Candida albicans for an extended period. Also, the formulation had no cytotoxic effect at the tested concentration. For the in vivo experiments, infected rabbits were successfully treated with local administration of the optimum NP formulation once a day. This study has shown that the mucoadhesive NP formulation containing fluconazole is a promising candidate with once-a-day application for the local treatment of oral candidiasis.

[Investigation of fluoroquinolone resistance mechanisms in clinical Acinetobacter baumannii isolates]. / Klinik Acinetobacter baumannii izolatlarinda florokinolon direnç mekanizmalarinin arastirilmasi.

Acinetobacter baumannii is an opportunistic pathogen which is one of the most important agents of nosocomial infections. Being resistant to many antibiotics, complicates the treatment of the infections caused. Fluoroquinolones are used in the treatment of nosocomial and community-acquired infections and it is important to determine the mechanisms of resistance to these antibiotics. The aims of this study were to investigate ciprofloxacin (CIP) and levofloxacin (LEV) minimum inhibitor concentrations (MIC), clonal relationships, mutations that occur in DNA gyrase and topoisomerase IV genes and overexpression of efflux pumps in nosocomial A.baumannii isolates. A total of 81 A.baumannii strains, 79 CIP-resistant and two CIP-susceptible, isolated from different clinical samples in Ege University Faculty of Medicine, Department of Medical Microbiology were included in the study. CIP and LEV MIC values were determined by broth microdilution method. Clonal relationship among the strains was investigated by ERIC-PCR (Enterobacterial repetitive intergenic consensus-polymerase chain reaction). Mutations that occur in gyrA and parC genes were detected by DNA sequence analysis in 16 strains representing each clone and subtype. Overexpression of the efflux pumps was evaluated by broth microdilution and fluorometric accumulation experiments were carried out in the presence of pump inhibitors, among the representative strains. MIC(50) and MIC(90) values for CIP were 256 µg/ml and ≥ 256 µg/ml, while the values were 32 µg/ml and 128 µg/ml for LEV, respectively. Overall, CIP MIC values were found to be higher than that of LEV among the A.baumannii strains studied. Isolates were grouped into six main groups and 10 different clusters (39 strains in cluster A, 20 in B, 13 in C, two of each in I and J, one of each in D-H clusters), but it was observed that the majority of them were clonally related. The most common and important mutations detected in the gyrA and parC genes of the representative isolates were, Ser83Leu, Asp87Glu and Ser80Leu, respectively. While the overexpression of efflux pumps was observed in seven of the representative strains by microdilution method, in 11 by fluorometric assay and the results were positive in five of the strains by both methods. CIP was found to be better than LEV for detecting the overexpression of pumps by the use of microdilution method. It was concluded that, the reason of high fluoroquinolone MIC values of the studied nosocomial and clonally related A.baumannii strains were related to target mutations and overexpression of efflux pumps besides the plasmid-mediated mechanisms, such as Qnr might also have played a role.

Antimicrobial Susceptibility and Clonal Relation Between Acinetobacter baumannii Strains at a Tertiary Care Center in Turkey.

BACKGROUND: Acinetobacter baumannii is an opportunistic pathogen, related with nosocomial infections such as bacteremia, urinary tract infections, and ventilator-associated pneumonia. Multidrug resistant (MDR) A. baumannii strains are first line causes of infection, especially in patients hospitalized at intensive care units (ICUs). Infection with MDR A. baumannii strains has a longer duration at ICUs and hospitals. There are studies using molecular methods which can differentiate MDR A. baumannii strains at the clonal level. This helps controlling these resistant strains and prevents their epidemy. OBJECTIVES: The aim of our study was to investigate the antimicrobial susceptibility and clonal relationship between the A. baumannii strains isolated from our ICU. MATERIALS AND METHODS: The identification and antimicrobial susceptibility of 33 A. baumannii strains were performed by automatized Vitek version 2.0. The clonal relationship among A. baumannii strains was analyzed using enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR). RESULTS: A total of 33 A. baumannii strains were included in this study. A. baumannii complex strains were classified into seven clusters based on the fingerprint results. Our results revealed that two main clusters were responsible for the prevalence of A. baumannii complex strains at the ICU. CONCLUSIONS: MDR A. baumannii strains cause an increment in morbidity and mortality, particularly in ICUs. The use of molecular epidemiological methods can help us with the detection of the pathogen and preventing from spreading of these resistant strains.

Evaluation of chitosan based vaginal bioadhesive gel formulations for antifungal drugs.

The aim of the present study was to evaluate chitosan as a vaginal mucoadhesive gel base for econazole nitrate and miconazole nitrate. To this aim, different types of chitosan with different molecular masses and viscosity properties [low molecular mass chitosan (viscosity: 20,000 mPa s), medium molecular mass chitosan (viscosity: 200,000 mPa s), high molecular mass chitosan (viscosity: 800,000 mPa s)] have been used. First, rheological studies were conducted on chitosan gels. Mechanical, syringeability and mucoadhesive properties of chitosan gels were determined. Release profiles of econazole nitrate and miconazole nitrate from chitosan gels were obtained and evaluated kinetically. In addition, anticandidal activities of formulations were determined. Finally, vaginal retention of chitosan gels in rats was evaluated by in vivo distribution studies. Based on the results, it can be concluded that gels prepared with medium molecular mass chitosan might be effectively used for different antifungal agents in the treatment of vaginal candidiosis, since it has high mucoadhesiveness, suitable mechanical and release properties with good vaginal retention.

[Investigation of the virulence factors of multidrug-resistant Acinetobacter baumannii isolates]. / Çok ilaca dirençli Acinetobacter baumannii izolatlarinda virülans faktörlerinin arastirilmasi

Acinetobacter baumannii is an opportunistic human pathogen which causes life-threatening nosocomial infections such as ventilator-associated pneumonia, bacteremia, meningitis, urinary tract and wound infections. Treatment options are very limited for infections caused by multi-drug resistant (MDR) A.baumannii strains. Until recently, the majority of studies related to A.baumannii have focused on antibiotic resistance, treatment protocols and epidemiological data, however, there have been few studies addressing the virulence factors of this organism. The features such as biofilm formation, serum resistance, motility, efflux pumps and iron acquisition mechanisms help the bacterium to survive in adverse environmental conditions and facilitate the development of an infection. The aim of the present study was to investigate the basic characteristics that contribute to the virulence of clinically important MDR A.baumannii isolates. Sixty-five ciprofloxacin-imipenem-trimethoprim/sulfamethoxazole-resistant A.baumannii strains isolated from various clinical specimens between December 2011 and March 2012 at Ege University Faculty of Medicine, Department of Medical Microbiology were included in the study. The clonal relationship of the isolates was analyzed by PCR using Enterobacterial repetitive intergenic consensus (ERIC)-2 primer. Biofilm formation, serum resistance, twitching and swarming motility, efflux pump and siderophore production were sought in representatives of each clone. Investigated MDR A.baumannii isolates were classified into seven main clusters, and the largest cluster included 86% of the strains. The virulence-associated features were investigated in 16 representative strains, including sub-groups. Twelve, three and one of the examined strains were determined to be strong, intermediate and weak biofilm producers, respectively. Siderophore production was not encountered in any of the isolates. Of the sixteen strains, two, one and thirteen isolates were found to be resistant, moderately susceptible and susceptible to bactericidal effect of serum, respectively. In our study, swarming motility was observed in seven strains while twitching motility was observed in only one strain. Swarming was simultaneously detected with twitching in one isolate. The presence of an efflux pump was investigated with ciprofloxacin in 16 representative strains but none of them were positive. However, eflux pump was determined in two of the five doxycycline resistant strains. Biofilm production was the most commonly observed characteristic among the examined strains. In addition, serum resistance, swarming and an efflux pump which has a spectrum including tetracyclines, were also determined among features associated with virulence. While the biofilm production was encountered at the members of all clones, serum resistance was found only in the representatives of the most dominant clone. Motility and the presence of an efflux pump were not associated with a particular clone. MDR A.baumannii strains are among the most important agents of nosocomial infections in our hospital and all over the world. Revealing the characteristics that play a role in the pathogenesis of these isolates, will contribute to infection control measures and to the investigation of new treatment options.

Investigation of in vitro antileishmanial activity of moxifloxacin, linezolid and caspofungin on Leishmania tropica promastigotes.

OBJECTIVE: This study aimed to evaluate the potential in vitro anti-leishmanial activities of moxifloxacin, linezolid and caspofungin against Leishmania tropica. METHODS: In vitro effects of all agents were studied by using the microdilution method. For this purpose, serial dilutions of the aforementioned agents were prepared in concentrations between 4096 µg/mL-0.008 µg/mL. Afterwards, promastigotes incubated in suitable medium were counted with the hemocytometer and adjusted as having a last concentration of 2.5 x 10(6) cells/mL in wells containing medium+antibiotic or antifungal. After incubation live promastigotes were counted with the hemocytometer and inhibitor concentrations (IC(50)) were determined by comparing with the control that contained no antibiotics or antifungal. RESULTS: IC(50) values of moxiloxacin, linezolid and caspofungin were found as 194.7 µg/mL, 896 µg/mL and 235.7 µg/mL, respectively. CONCLUSION: As a result, moxifloxacin was found to be effective in lower concentrations than the other studied agents against L. tropica promastigotes.

Prevalence of blaPER-1 and integrons in ceftazidime-resistant Gram-negative bacteria at a university hospital in Turkey.

In this study, we examined the prevalence of the PER-1 enzyme and the presence of clinically important integron classes in ceftazidime-resistant Gram-negative bacteria isolated at a university hospital. The blaPER-1 gene was detected by PCR in 33 (19.5%) of the total 169 Gram-negative bacteria, including 17 (23.3%) of the 73 Pseudomonas aeruginosa isolates and 16 (25%) of the 64 Acinetobacter baumannii complex isolates. Molecular fingerprinting revealed that blaPER-1 prevalence was mostly due to the dissemination of clonally related P. aeruginosa and A. baumannii complex strains. Class 1 integron (intI1) was detected in 52.7% of the 169 bacteria examined in this study. Its detection rates were estimated at 49.3% and 57.8% of the P. aeruginosa and A. baumannii complex strains isolated, respectively. It was also detected in 11 of the 16 Escherichia coli isolates and 5 of the 10 Klebsiella pneumoniae isolates. A single E. coli isolate and another K. pneumoniae isolate contained both class 1 and class 2 integrase genes. The results of this study revealed that clonally related blaPER-1-positive P. aeruginosa and A. baumannii complex strains, mostly harboring intI1, had disseminated at our hospital.

Synthesis and antileishmanial activity of novel pyridinium-hydrazone derivatives.

A series of substituted phenylethylidenehydrazinylpyridinium derivatives bearing methyl, ethyl, propyl, and propylphenyl groups on the pyridinium nitrogen were synthesized and evaluated for in vitro antileishmanial activity against Leishmania tropica by using the microdilution method. Among the tested compounds, 3d, 5c, 3b, and 3c were found to be the most active derivatives against the promastigotes of L. tropica (IC50 values are 6.90, 9.92, 11.69 and 12.03 µM, respectively) and to be more active than reference drug meglumine antimonaite (glucantime) (IC50 value: 20.49 µM). The derivatives investigated in this study may have the potential to be lead compound against leishmanial infection.

Plasmid-mediated quinolone resistance mechanisms in ESBL positive Escherichia coli and Klebsiella pneumoniae strains at a Tertiary-Care Hospital in Turkey.

Plasmid-mediated quinolone resistance mechanisms in extended spectrum beta-lactamase positive and quinolone resistant Escherichia coli and Klebsiella pneumoniae strains isolated from Ege University Hospital were investigated. The presence of qnrA, qnrB, qnrS, aac(6')-Ib and qepA genes were detected by PCR and the products were sequenced. Clonal relationship of isolates was determined by REP-PCR and mutations in gyrA and parC genes were investigated in representative strains. aac(6')-Ib-cr, qnrB and qnrS genes were detected in both E. coli and K. pneumoniae strains, but qnrA detected only in K. pneumoniae strains. qepA determinant is detected in an E. coli strain first time in Turkey. Mutations were observed in both gyrA and parC genes of all representative nalidixic acid and ciprofloxacin resistant E. coli isolates but no mutation was found in parC genes of E. coli and K. pneumoniae strains that were resistant to only nalidixic acid.

The evaluation of clusters of hospital infections due to multidrug-resistant Salmonella enterica serovar typhimurium in the neonatal unit: a two-year experience.

Seven clusters of hospital infection due to Salmonella enterica serovar typhimurium were documented in the neonatology clinic of a children's hospital between April 2002 and March 2004. Eighty-one neonates were infected. Three cases were asymptomatic, 73 cases had gastroenteritis as the only clinical condition, and 5 cases had bacteremia associated with gastroenteritis. All isolates from stool and blood samples (n=86) were identified as Salmonella enterica serovar typhimurium. Extended-spectrum beta-lactamase (ESBL) production was determined by clavulanate disk potentiation assay in all isolates. Enterobacterial Repetitive Intergenic Consensus polymerase chain reaction (ERIC-PCR) was performed in 26 selected isolates, which were chosen as being representative of different clusters, to determine the clonal relationship. PCR, isoelectric focusing and sequence analysis revealed the production of CTX-M-3, TEM-1 and SHV-12 by these isolates in 23%, 76.9% and 100%, respectively. None of the isolates had PER beta-lactamase production. Standard infection control measures such as handwashing and disinfection procedures were implemented in initial clusters. During the two-year period, the infection control policy of the hospital was improved with appropriate actions such as assignment of an infection control nurse and increasing the number of staff of the clinic, and finally, with the establishment of an active surveillance program, the clusters were stopped.

In vitro activity of linezolid against Mycobacterium tuberculosis strains isoalted from Western Turkey.

We investigated the linezolid susceptibility of Mycobacterium tuberculosis strains isolated from a tertiary care hospital in Izmir. A total of 67 M. tuberculosis strains (33 multidrug-resistant [MDR] and 34 non-MDR) were isolated and identified by the Tuberculosis Laboratory, Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Ege University. The activity of linezolid was studied by the standard agar proportion method. For all of the strains, the MIC range was 0.06-1 mg/L, and the MIC(50) and MIC(90) values were 0.5 mg/L. No differences were observed between the MDR and non-MDR isolates. In general, linezolid was found to be effective for both the non-MDR and MDR M. tuberculosis strains.

[In vitro activity of linezolid/ertapenem combination in resistant gram-positive bacteria]. / Dirençli gram-pozitif bakterilerde linezolid/ertapenem kombinasyonunun in vitro aktivitesi.

The increasing prevalence of vancomycin-resistant enterococcus and methicillin-resistant staphylococcus infections has become a major therapeutic challenge and alternative therapy options are under consideration. In the present study, we aimed to evaluate the in vitro antibacterial activity of linezolid combined with ertapenem against two vancomycin-resistant Enterococcus faecium (VREF), two methicillin-resistant Staphylococcus aureus (MRSA) and two methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from clinical specimens. In vitro activity of linezolid/ertapenem combination at 1/2 x MIC (minimal Inhibitory Concentration), 1 x MIC and 4 x MIC concentrations for each of the isolates was determined by time-kill curve method. At 1 x MIC and 4 x MIC concentrations, additive effect was detected for MRSA (at 6 and 24 h) and VREF (at 6 h) strains. Synergism was observed between two antibiotics at 4 x MIC concentration against one of the MRSE strains at 6th hour. Additive effect was determined at 6th and 24th hours in this strain at 1 x MIC concentration. No synergism was present in the other MRSE strain but additive interaction was detected at 6 h (1/2 x MIC) and 24 h (1 x MIC). Although these results support the use of linezolid/ertapenem combination in infections caused by resistant gram-positive strains, further in vitro and in vivo studies are necessary.