In vitro anti-leukemic effect of Wharton's jelly derived mesenchymal stem cells.

BACKGROUND: Mesenchymal stem cells (MSCs) have the ability to self-renew and are multi-potent. They are a primary candidate for cell-based therapy due to their potential anti-cancer effects. The aim of this study was to evaluate the in vitro anti-leukemic effect of Wharton's Jelly-derived MSC (WJ-MSC) on the leukemic cell lines K562 and HL-60. METHODS: In this present study, WJ-MSCs were isolated from human umbilical cord. The cells were incubated according to the standard culture conditions and characterized by flow cytometry. For experiments, WJ-MSC and leukemic cells were incubated in the direct co-culture at a ratio of 1:5 (leukemia cells: WJ-MSC). HUVEC cells were used as a non-cancerous cell line model. The apoptotic effect of WJ-MSCs on the cell lines was analyzed using Annexin V/PI apoptosis assay. RESULTS: After the direct co-culture of WJ-MSCs on leukemic cell lines, we observed anti-leukemic effects by inducing apoptosis. We had two groups of determination apoptosis with and without WJ-MSCs for all cell lines. Increased apoptosis rates were observed in K562 and HL-60 cell lines, whereas the apoptosis rates in HUVEC cells were low. CONCLUSIONS: MSCs are known to inhibit the growth of tumors of both hematopoietic and non-hematopoietic origin in vitro. In our study, WJ-MSC treatment strongly inhibited the viability of HL-60 and K562 and induced apoptosis. Our results also provided new insights into the inhibition of tumor growth by WJ-MSCs in vitro. In the future, WJ-MSCs could be used to inhibit cancer cells in clinical applications.

Trends of Antibiotic Resistance in Multidrug-Resistant Pathogens Isolated from Blood Cultures in a Four-Year Period.

BACKGROUND: Multidrug-resistant organisms cause serious infections with significant morbidity and mortality in the worldwide. These organisms have been identified as urgent and serious threats by CDC. The aim of this study was to determine the prevalence and changes of antibiotic resistance of multidrug-resistant pathogens isolated from blood cultures over a four-year period in a tertiary-care hospital. METHODS: Blood cultures were incubated in a blood culture system. Positive signalling blood cultures were subcultured on 5% sheep-blood agar. Identification of isolated bacteria was performed using conventional or automated identification systems. Antibiotic susceptibility tests were performed by disc diffusion and/or gradient test methods, if necessary, by automated systems. The CLSI guidelines were used for interpretation of antibiotic susceptibility testing of bacteria. RESULTS: The most frequently isolated Gram-negative bacteria was Escherichia coli (33.4%) followed by Klebsiella pneumoniae (21.5%). ESBL positivity was 47% for E. coli, 66% for K. pneumoniae. Among E. coli, K. pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii isolates, carbapenem resistance was 4%, 41%, 37%, and 62%, respectively. Carbapenem resistance of K. pneumoniae isolates has increased from 25% to 57% over the years, and the highest rate (57%) occured during the pandemic period. It is noteworthy that the aminoglycoside resistance in E. coli isolates gradually increased from 2017 to 2021. The rate of methicillin-resistant S. aureus (MRSA) was found to be 35.5%. CONCLUSIONS: Increased carbapenem resistance in K. pneumoniae and A. baumannii isolates is noteworthy, but carbapenem resistance in P. aeruginosa decreased. It is of great importance for each hospital to monitor the increase in resistance in clinically important bacteria, especially isolated from invasive samples, in order to take the necessary precautions in a timely manner. Future studies involving clinical data of patients and bacterial resistance genes are warranted.

Country data on AMR in Türkiye in the context of community-acquired respiratory tract infections: links between antibiotic susceptibility, local and international antibiotic prescribing guidelines, access to medicine and clinical outcome.

BACKGROUND: Antimicrobial resistance (AMR) is one of the biggest threats to global public health. Selection of resistant bacteria is driven by inappropriate use of antibiotics, amongst other factors. COVID-19 may have exacerbated AMR due to unnecessary antibiotic prescribing. Country-level knowledge is needed to understand options for action. OBJECTIVES: To review AMR in Türkiye and initiatives addressing it. Identifying any areas where more information is required will provide a call to action to minimize any further rise in AMR within Türkiye and to improve patient outcomes. METHODS: National AMR initiatives, antibiotic use and prescribing, and availability of susceptibility data, particularly for the key community-acquired respiratory tract infection (CA-RTI) pathogens Streptococcus pneumoniae and Haemophilus influenzae, were identified. National and international antibiotic prescribing guidelines commonly used locally for specific CA-RTIs (community-acquired pneumonia, acute otitis media, acute bacterial rhinosinusitis) were also reviewed, plus local antibiotic availability. Insights from both a local clinician and local clinical microbiologist were sought to contextualize this information. CONCLUSIONS: Türkiye developed an antibiotic stewardship programme, The Rational Drug Use National Action Plan 2014-2017, prioritizing appropriate antibiotic prescription in the community. Public campaigns discouraging inappropriate antibiotic use were also initiated. Türkiye has a high level of antibiotic resistance and a high level of consumption, however, in 2015 over-the-counter antibiotic sales were prohibited, resulting in a declining trend in overall consumption. There is still a need for physician education on current developments in antibiotic use. Several ongoing global surveillance studies provide antibiotic susceptibility data in Türkiye. Clinicians in Türkiye use several country-specific guidelines for common CA-RTIs plus a range of international guidelines. A more standardized inclusive approach in developing local guidelines, using up-to-date surveillance data on isolates from community-acquired infections in Türkiye, could make guideline use more relevant for clinicians. This would pave the way for a higher level of appropriate antibiotic prescribing and improved adherence. This would, in turn, potentially limit AMR development and improve patient outcome.

Time kill-assays of antibiotic combinations for multidrug resistant clinical isolates of OXA-48 carbapenemase producing Klebsiella pneumoniae.

Treatment of infections caused by OXA-48 carbapenemase producing multidrug-resistant isolates often necessitates combination therapy. In vitro effect of different antibiotic combinations against multidrug-resistant (MDR) Klebsiella pneumoniae isolates were evaluated in this study.Meropenem-tobramycin (MER+TOB), meropenem-ciprofloxacin (MER+CIP), colistin-meropenem (COL+MER), colistin-ciprofloxacin (COL+CIP) and colistin-tobramycin (COL+TOB) combinations were tested by time kill-assays. Each antibiotic alone and in combination at their Cmax values were tested against 4 clinical K. pneumoniae isolates at 1, 2, 4, 6, 8, 12 and 24 h. Effect of colistin and its associations were also assessed at 30 min. Bactericidal activity was defined as ≥3log10 CFU mL-1 decrease compared with initial inoculum. Synergy was defined as ≥2log10CFU mL-1 decrease by the combination compared with the most active single agent. Presence of blaOXA-48, blaNDM, blaVIM, blaIMP, blaKPC and blaCTX-M-1 genes was screened by PCR using specific primers.The blaOXA-48 gene was identified together with blaCTXM-1 group gene in all isolates. COL+MER demonstrated to be synergistic and bactericidal. MER+TOB showed synergistic and bactericidal effect on two strains although, regrowth was seen on other two strains at 24 h. MER+CIP exhibited indifferent effect on the strains.Combination therapy could be a potential alternative to treat MDR K. pneumoniae infections. This combination might prevent resistance development and secondary effects of colistin monotherapy. MER+TOB and MER+CIP might have an isolate-dependent effect, that may not always result in synergism.

Comparison of Four Phenotypic Assays and Check-Direct CPE for Detection of Carbapenemases-Producing Enterobacterales.

BACKGROUND: Early and accurate detection of carbapenemase-producing Enterobacterales (CPE) is fundamental to prevent their spread in hospital environment. Our objective was to compare between four commonly used phenotypic assays and Check-Direct CPE (CDCPE) multiplex PCR in CPE detection. We examined stool samples or rectal swabs for CPE, samples collected from 23 Jan 2017 to 23 Jul 2017 from patients in intensive-care units (ICUs) of our hospital. METHODS: A panel of 98 non-repetitive Enterobacterales isolates with reduced susceptibility to carbapenems were analyzed by means of (i) Modified Hodge Test (MHT), (ii) Blue Carba test (BCT), (iii) Combined Disc Test (CDT), and (iv) The Carbapenem Inactivation Method (CIM). All these phenotypic tests compared with CDCPE. Confirmation and validation of results was achieved by classical PCR and sequencing. RESULTS: Of the 98 non-repetitive Enterobacterales isolates, ninety-one were K. pneumoniae (93%), three K. oxytoca (3%), three E. cloacae (3%) and one E. coli (1%). By classic PCR the carbapenem resistance genes in K. pneumoniae isolates distributed as the followings; 49 blaOXA-48, 34 both blaOXA-48 and blaNDM-1, seven blaNDM-1 and one blaKPC. K. oxytoca; two blaOXA-48, one blaNDM-1. E. cloacae; two blaOXA-48, one blaNDM-1. E. coli; one isolate with both blaOXA-48 and blaNDM-1. The most common carbapenemase gene detected was blaOXA-48 rate of 54% (n = 53) followed by a combination of both blaOXA-48 and blaNDM-1 with rate of 36% (n = 35), only blaNDM-1 9% (n = 9) and blaKPC 1% (n = 1). Among phenotypic tests, we found CIM, MHT, and BCT correctly identified carbapenemase producers with sensitivity of 100%, 98%, and 90.8%, respectively. CONCLUSIONS: Rapid and accurate detection of CRE can be achieved by combination of both phenotypic and molecular tests. Surveillance studies are important both in terms of epidemiology and regulation of the treatment of patients.

Clonal distribution of vancomycin-resistant Enterococcus faecium in Turkey and the new singleton ST733.

BACKGROUND: The aim of this study was to provide information about the spread and characteristics of the vancomycin-resistant Enterococcus faecium isolates (VREfm) in Turkey. METHODS: Seventy-one nonduplicate consecutive isolates of VREfm were obtained from various clinical specimens of inpatients treated at university or training hospitals in seven regions of Turkey. Further characteristics included antibiotic susceptibility testing, pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, and multilocus sequence typing (MLST) of selected isolates. The presence of vancomycin resistance and virulence genes (esp and hyl) was investigated by polymerase chain reaction (PCR). RESULTS: All VREfm isolates had MICs to vancomycin of ≥32 mg/L and contained the vanA gene. The presence of esp gene was identified in 64 and hyl in eight VREfm isolates. All VREfm showed the multiresistance phenotype, including ampicillin (99%), penicillin (99%), imipenem (99%), ciprofloxacin (87%), moxifloxacin (87%), erythromycin (97%), streptomycin (86%), gentamicin (82%), tetracycline (70%), and teicoplanin (99%). All were susceptible to tigecycline while quinupristin-dalfopristin (97%) and linezolid (93%) were the most active other agents. Analysis of the PFGE profiles showed that 53 (74.6%) VREfm isolates shared a similar electrophoretic profile, designed as type 1, and were closely related (>85%). The sequence type was identified by MLST in 44 VRE isolates with unrelated or closely related PFGE patterns. MLST revealed that nosocomial spread of VREfm resulted from dissemination of lineage C1 E faecium clones. Sequence types ST78, ST203, and ST117 were the most frequently isolated. This is the first report of ST733 around the world. CONCLUSIONS: Lineage C1 clones are disseminated among clinical VREfm isolates in seven different regions in Turkey. Regarding VREfm isolates, the worldwide epidemic strains are in circulation in Turkey.

Comparison of the Novel Oxa-48 and Kpc K-SeT Assay, and Blue-Carba Test for the Detection of Carbapenemase-Producing Enterobacteriaceae Using PCR as a Reference Method.

BACKGROUND: Rapid, simple, and accurate laboratory detection of carbapenemases is very important for proper antibiotic therapy and infection control. METHODS: In this study, carbapenem-nonsusceptible Enterobacteriaceae (CRE) isolates were used to evaluate the performance of a new lateral flow immunochromatographic (IC) assay, the OXA-48 and KPC K-SeT assay, and modified Blue-Carba test (BCT) for the rapid detection of OXA-48 carbapenemase in comparison with polymerase chain reaction (PCR) amplification. These CREs of various enterobacterial species were isolated from various clinical samples including OXA-48 (47), NDM-1 (6), KPC-1 (1), IMP-1 (1), VIM-2,-4 (2), IMP-2 (1), OXA-51 (1), and OXA-23 (1) producers. RESULTS: The OXA-48 K-SeT test detected all OXA-48 carbapenemase producers with 100% sensitivity and specificity. The BCT detected carbapenemase producers with 93% sensitivity and 100% specificity. CONCLUSIONS: Both IC assays and BCT tests have good performance and are easy to perform, rapid, simple to interpret, and highly sensitive. We suggest that BCT can be used initially as an accurate, inexpensive, and rapid phenotypic confirmation test to identify Class A, B, and D carbapenemases in the routine diagnostic microbiology laboratory, thus allowing the detection of carbapenemase activity directly from bacterial cultures.

The First Enterobacter cloacae Co-Producing NDM and OXA-48 Carbapenemases and Interhospital Spread of OXA-48 and NDM-Producing Klebsiella pneumoniae in Turkey.

BACKGROUND: The aim of this study was to investigate the occurrence of carbapenemase-producing Enterobacteriaceae. METHODS: A total of 54 carbapenem nonsusceptible Enterobacteriaceae (CRE) isolates were recovered from clinical samples sent to the Dr. Lutfi Kirdar Kartal Training and Research Hospital from the period 2011 through 2014. Forty-four isolates were Klebsiella pneumoniae (CRKP) and the other 10 were Enterobacter cloacae (CREC).The isolate identifications and antibiotic sensitivity tests were performed using a Vitek2 automatic system. The clonality of isolates was determined using rep-PCR Diversilab. Presence of blaOXA-48, blaNDM, blaVIM, blaIMP, and blaKPC genes were screened using polymerase chain reaction (PCR) with specific primers. RESULTS: CRKP were isolated from blood, urine, wounds, catheter tips, and tracheal aspirate samples; a total 44 isolates were evaluated. All isolates were nonsusceptible to ertapenem/imipenem or meropenem. Eighteen percent of the isolates were resistant to colistin. CREC were isolated from blood, urine, cerebrospinal fluid and sputum; a total of 10 isolates were evaluated. They were resistant to all carbapenems and 90% were resistant to cefoperazone/sulbactam and trimethoprim/sulfamethoxazole, and 50 - 70% isolates were resistant to gentamicin, amikacin, and ciprofloxacin. Thirty-three (75%) OXA-48 producing CRKP were identified. Thirteen (29.5%) were positive and two (4.5%) NDM-producing K. pneumoniae were co-producing OXA-48. Of the ten CREC strains tested, eight were positive for blaNDM, one isolate was positive for blaVIM and another for blaIMP genes. rep-PCR typing revealed the presence of a clonal dissemination in CRKP and CREC in the hospital. CONCLUSIONS: To our knowledge, this is the first identification of blaNDM in E. cloacae isolates in Turkey. These findings describe an interhospital spread of CRKP-producing OXA-48 and NDM carbapenemases that started in 2011. Continuous monitoring is necessary to better understand their dissemination in the hospital, which probably occurred as a result of transmission from an environmental reservoir. These findings emphasize the need for intensive surveillance and precautions.

[Investigation of carbapenemases in carbapenem-resistant Escherichia coli and Klebsiella pneumoniae strains isolated in 2014 in Turkey]. / Türkiye'de 2014 yili içinde izole edilen karbapeneme dirençli Escherichia coli ve Klebsiella pneumoniae izolatlarinda karbapenemaz varliginin arastirilmasi.

Carbapenems are the choice of treatment in infections caused by multidrug resistant Enterobacteriaceae. In recent years carbapenem-resistant Enterobacteriaceae isolates due to carbapenemases have been increasingly reported worldwide. Multicenter studies on carbapenemases are scarce in Turkey. The aim of this study was to determine the distribution of carbapenemases from different parts of Turkey as a part of the European Survey of Carbapenemase Producing Enterobacteriaceae (EuSCAPE) project. Beginning in November 2013, carbapenem-resistant isolates resistant to at least one of the agents, namely imipenem, meropenem, and ertapenem were sent to the coordinating center. Minimum inhibitory concentrations for these carbapenems were determined by microdilution tests following EUCAST guidelines. Production of carbapenemase was confirmed by combination disk synergy tests. Types of carbapenemases were investigated using specific primers for VIM, IMP; NDM, KPC and OXA-48 genes by multiplex polymerase chain reaction. In a six month period, 155 suspected carbapenemase-positive isolates were sent to the coordinating center of which 21 (13.5%) were E.coli and 134 (86.5%) were K.pneumoniae. Nineteen (90.5%) strains among E.coli and 124 (92.5%) strains among K.pneumoniae were shown to harbour at least one carbapenemase gene by molecular tests, with a total of 92.3% (143/155). Carbapenemases were determined as a single enzyme in 136 strains (OXA-48: 84.6%; NDM: 6.3%; VIM: 2.8%; IMP: 1.4%) and as a combination in seven isolates (OXA-48 + NDM: 2.1%; OXA-48 + VIM: 2.1%; VIM + NDM: 0.7%). KPC was not detected in any of the isolates. According to the microdilution test results, resistance to imipenem, meropenem and ertapenem in OXA-48 isolates were 59.5%, 52.9% and 100%, respectively. The combination disk synergy test was 100% compatible with the molecular test results. As most of the OXA-48 producing isolates were susceptible to meropenem but all were resistant to ertapenem, ertapenem seems to be the most sensitive agent in screening carbapenemases in areas where OXA-48 is prevalent and phenotypic combination tests can be useful in centers where molecular tests are not available.

Antimicrobial Activity of Fosfomycin-Tobramycin Combination against Pseudomonas aeruginosa Isolates Assessed by Time-Kill Assays and Mutant Prevention Concentrations.

The antibacterial activity of fosfomycin-tobramycin combination was studied by time-kill assay in eight Pseudomonas aeruginosa clinical isolates belonging to the fosfomycin wild-type population (MIC = 64 µg/ml) but with different tobramycin susceptibilities (MIC range, 1 to 64 µg/ml). The mutant prevention concentration (MPC) and mutant selection window (MSW) were determined in five of these strains (tobramycin MIC range, 1 to 64 µg/ml) in aerobic and anaerobic conditions simulating environments that are present in biofilm-mediated infections. Fosfomycin-tobramycin was synergistic and bactericidal for the isolates with mutations in the mexZ repressor gene, with a tobramycin MIC of 4 µg/ml. This effect was not observed in strains displaying tobramycin MICs of 1 to 2 µg/ml due to the strong bactericidal effect of tobramycin alone. Fosfomycin presented higher MPC values (range, 2,048 to >2,048 µg/ml) in aerobic and anaerobic conditions than did tobramycin (range, 16 to 256 µg/ml). Interestingly, the association rendered narrow or even null MSWs in the two conditions. However, for isolates with high-level tobramycin resistance that harbored aminoglycoside nucleotidyltransferases, time-kill assays showed no synergy, with wide MSWs in the two environments. glpT gene mutations responsible for fosfomycin resistance in P. aeruginosa were determined in fosfomycin-susceptible wild-type strains and mutant derivatives recovered from MPC studies. All mutant derivatives had changes in the GlpT amino acid sequence, which resulted in a truncated permease responsible for fosfomycin resistance. These results suggest that fosfomycin-tobramycin can be an alternative for infections due to P. aeruginosa since it has demonstrated synergistic and bactericidal activity in susceptible isolates and those with low-level tobramycin resistance. It also prevents the emergence of resistant mutants in either aerobic or anaerobic environments.

Effect of N-acetyl cysteine, rifampicin, and ozone on biofilm formation in pan-resistant Klebsiella pneumoniae: an experimental study.

BACKGROUND: To the best of our knowledge, this is the first study to evaluate the effectiveness of specific concentrations of antibiofilm agents, such as N-acetyl cysteine (NAC), rifampicin, and ozone, for the treatment of pan-resistant Klebsiella pneumoniae (PRKp). OBJECTIVES: We evaluated the effectiveness of antibiofilm agents, such as NAC, rifampicin, and ozone, on biofilm formation in PRKp at 2, 6, 24, and 72 h. DESIGN AND SETTING: This single-center experimental study was conducted on June 15, 2017, and July 15, 2018, at Istanbul Faculty of Medicine, Istanbul University, Turkey. METHODS: Biofilm formation and the efficacy of these agents on the biofilm layer were demonstrated using colony counting and laser-screened confocal microscopy. RESULTS: NAC at a final concentration of 2 µg/mL was administered to bacteria that formed biofilms (24 h), and no significant decrease was detected in the bacterial counts of all isolates (all P > 0.05). Rifampicin with a final concentration of 0.1 µg/mL was administered to bacteria that formed biofilm (24 h), and no significant decrease was detected in bacterial count (all P > 0.05). Notably, ozonated water of even 4.78 mg/L concentration for 72 h decreased the bacterial count by ≥ 2 log10. CONCLUSION: Different approaches are needed for treating PRKp isolates. We demonstrate that PRKp isolates can be successfully treated with higher concentrations of ozone.

Efficacy of antibiotic combinations in an experimental sepsis model with Pseudomonas aeruginosa.

This study aimed to compare the efficacy of fosfomycin, colistin, tobramycin and their dual combinations in an experimental sepsis model. After sepsis was established with a Pseudomonas aeruginosa isolate (P1), antibiotic-administered rats were divided into six groups: Fosfomycin, tobramycin, colistin and their dual combinations were administered by the intravenous or intraperitoneal route to the groups. The brain, heart, lung, liver, spleen and kidney tissues of rats were cultured to investigate bacterial translocation caused by P1. Given the antibiotics and their combinations, bacterial colony counts in liver tissues were decreased in colistin alone and colistin plus tobramycin groups compared with control group, but there were no significant differences. In addition, a non-statistical decrease was found in the spleen tissues of rats in the colistin plus tobramycin group. There was a > 2 log10 CFU/ml decrease in the number of bacterial colonies in the kidney tissues of the rats in the fosfomycin group alone, but the decrease was not statistically significant. However, there was an increase in the number of bacterial colonies in the spleen and kidney samples in the group treated with colistin as monotherapy compared to the control group. The number of bacterial colonies in the spleen samples in fosfomycin plus tobramycin groups increased compared to the control group. Bacterial colony numbers in all tissue samples in the fosfomycin plus colistin group were found to be close to those in the control group. Colistin plus tobramycin combinations are effective against P. aeruginosa in experimental sepsis, and clinical success may be achieved. New in vivo studies demonstrating the ability of P. aeruginosa to biofilm formation in tissues other than the lung are warranted in future.

Molecularly imprinted nanoparticles with recognition properties towards diphtheria toxin for ELISA applications.

Plastic antibodies can be used for in vitro neutralization of biomacromolecules with different fragments due to their potential in separation, purification, chemical sensor, catalysis and drug production studies. These polymer nanoparticles with binding affinity and selectivity comparable to natural antibodies were prepared using functional monomer synthesis and copolymerization of acrylic monomers via miniemulsion polymerization. As a result, the in vitro cytotoxic effect from diphtheria toxin was reduced by MIPs. In vitro imaging experiments of polymer nanoparticles (plastic antibodies) were performed to examine the interaction of diphtheria toxin with actin filaments, and MIPs inhibited diphtheria toxin damage on actin filaments. The enzyme-linked immunosorbent assay (ELISA) was performed with plastic antibodies labeled with biotin, and it was determined that plastic antibodies could also be used for diagnostic purposes. We report that molecularly imprinted polymers (MIPs), which are biocompatible polymer nanoparticles, can capture and reduce the effect of diphtheria toxic and its fragment A.

Macromolecules can be imprinted by using their fragments as template molecules.MIPs gain an affinity for the template molecule by covalent binding, non-covalent interactions or ligand interactions, as well as the ability to bind, release and recognize the template molecule.The viability of cells treated with DT, NIPs and MIPs was determined by MTT assay.Immunofluorescence staining studies examined structural changes in actin filaments in HUVEC treated with DT, NIPs and MIPs.FA imprinted polymer has the ability to bind whole diphtheria toxin.FA-MIP gave significant results in terms of specificity in ELISA using diphtheria toxin.

[Antibiotic susceptibility rates and beta-lactam resistance mechanisms of Pseudomonas aeruginosa strains]. / Pseudomonas aeruginosa Suslarinda Antibiyotik Duyarlilik Oranlari ve Beta-Laktam Direnç Mekanizmalarinin Tiplendirilmesi.

Pseudomonas aeruginosa is a well-known cause of severe and potentially life-threatening infections including bacteremia, skin and wound infections, pulmonary disease, especially among individuals with cycstic fibrosis, nosocomial urinary tract infections, endocarditis and meningitis. The mechanism of resistance to broad-spectrum beta-lactams in P.aeruginosa are overexpression of cephalosporinases and/or class A, B and D beta-lactamases. Recently PER-1 type beta-lactamase has been reported from Turkey, France, Italy, Romania, Hungary, Belgium, Russia, South Korea and India. OXA beta-lactamases have increasingly been reported in clinical strains of P.aeruginosa from various geographical origins. This study was aimed to investigate the antibiotic susceptibility of various P.aeruginosa clinical strains and to define the beta-lactamase enzymes leading to resistance. In this study, a total of 100 P.aeruginosa strains isolated from various clinical specimens (37 urine, 21 blood, 10 sputum, 5 bronchoalveolar lavage, 5 abscess, 5 wound swabs, 4 endotracheal aspirate, 3 throat swabs, 2 catheter tips, one of each pleural and peritoneal fluid) were included. According to Clinical and Laboratory Standards Institute (CLSI) recommendations, susceptibilities of isolates to various antibiotics were investigated by disk diffusion and agar dilution method, and beta-lactamase enzymes were detected by isoelectric focusing (IEF) method. PSE, PER-1, OXA-10-like beta-lactamase genes and MEX-R genes of isolates were investigated by polymerase chain reaction (PCR). According to MIC90 values, the most effective antibiotics were found to be imipenem (8 µg/ml). The MIC90 values of amikacin, ciprofloxacin, cefepime, cefpirome, piperacillin + tazobactam, piperacillin, ceftazidime, ticarcilin, aztreonam and ticarcilin + clavulanic acid were 32, 64, 64, 64, 128/4, 512, 512, 512, 512 and 512/2 µg/ml, respectively. Seven of the isolates were found to be ESBL positive by double-disk synergy method. It was detected that 10% of the isolates were imipenem-susceptible and 9% were intermediate susceptible. Phenotypical investigation of metallo-beta-lactamase enzyme in these strains by MBL E-test method did not reveal a positive result. PER-1 and OXA-10 like beta-lactamases were detected each in 11% of the isolates, and co-presence of PER-like and OXA-10 like enzymes were shown in 4% of the isolates. PSE gene was not found in any of the strains. The MEXR gene was identified in 52% of the isolates. Antibiotic resistance mechanisms in P.aeruginosa strains seems to be complex. Determination of the resistance mechanisms and antibiotic susceptibility rates in P.aeruginosa will guide the proper antimicrobial therapy, reducing the emergence of resistant strains.

Biofilm formation of panresistant Klebsiella pneumoniae.

Introduction: The authors aimed to investigate the biofilm-forming features of panresistant Klebsiella pneumoniae (PRKp). Material & methods: The biofilm formations were shown under light microscope and laser scanning confocal microscopy. The optical densities of the wells were measured and classified according to biofilm-forming capacities. Results: The ratio of biofilm-forming K. pneumoniae was established to be 100%. All isolates were found to form high-level biofilms in classification compared with positive and negative controls. No significant difference was detected in the biofilm-forming capacities of K. pneumoniae strains isolated from different sample types. Conclusion: No previous study associated with PRKp isolates was identified in the literature search. There is a need for different approaches characterizing the biofilm-forming features of PRKp.

In vitro activities of antibiotic combinations against mature biofilms of ventilator-associated pneumonia isolates.

Background: The authors aimed to determine the efficacy of frequently used antibiotics, alone or in combination, against biofilms of ventilator-associated pneumonia isolates. Materials & methods: The authors determined the MICs, minimum biofilm inhibitory concentrations and minimum biofilm eradication concentrations of meropenem, ciprofloxacin and colistin as well as their combinations against planktonic forms and biofilms of Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii clinical isolates. Results: Generally, the minimum biofilm inhibitory concentrations and minimum biofilm eradication concentrations of the antibiotics were 1000-fold higher than their MICs, and synergy was provided by different concentrations of meropenem-colistin and meropenem-ciprofloxacin combinations with checkerboard and time-kill curve methods. Conclusion: The combination of meropenem and ciprofloxacin seems to be a good candidate for the treatment of biofilm-associated infections; none of the concentrations obtained as a result of the synergy test were clinically significant.

In vitro evaluation of double carbapenem and colistin combinations against OXA-48, NDM carbapenemase-producing colistin-resistant Klebsiella pneumoniae strains.

BACKGROUND: Treatment of pandrug-resistant isolates often necessitates combination therapy. Checkerboard synergy and time-killing assay tests were performed to evaluate the benefits of a triple combination with meropenem, ertapenem, and colistin against 10 colistin-resistant K. pneumoniae clinical isolates harboring different ß-lactamases. (blaOXA-48, blaNDM). MATERIALS AND METHODS: In this study, ertapenem and meropenem (ERT/MEM), meropenem and colistin (MEM/COL), ertapenem, meropenem and colistin (ERT/MEM/COL) combinations were tested using checkerboard techniques and time-kill assays of each antibiotic alone and in combination against 10 colistin-resistant clinical K. pneumoniae isolates. An analysis of K. pneumoniae isolate B6 using a scanning electron microscope revealed morphologic changes in the cell surface after treatment with each antibiotic both alone and in combination. The whole genome of K. pneumoniae KPNB1 was sequenced using an Ion Torrent PGM sequencer. RESULTS: According to the checkboard results, synergistic combinations were observed with ertapenem/meropenem (5/10 isolates), meropenem/colistin (7/10) and ertapenem/meropenem/colistin (9/10); no antagonism was observed for all combinations. For the time-kill assay results; synergism and bactericidal effects were observed with meropenem/colistin (10/10) and with ertapenem/meropenem/colistin (10/10) combinations, and an indifference effect was observed with the ertapenem and meropenem (10/10) combination. Strain number 1 was found 100% identical to Klebsiella pneumoniae subsp. pneumoniae HS11286 according to the outcomes of complete genome sequence analysis, and the strain carried the genes blaOXA-181, blaCTXM-15, blaNDM, arr-3, aac (6')-Ib-cr, rmtF, and catB1. CONCLUSION: Using double carbapenem antibiotics with colistin could be a potential alternative to treat colistin and carbapenem-resistant K. pneumoniae. The present study is the first Turkish report of OXA-181-type carbapenemase causing colistin resistance.

Polymeric nanoparticles for selective protein recognition by using thiol-ene miniemulsion photopolymerization.

The fabrication of molecularly imprinted nanoparticles (MIP-NPs) specific for myoglobin by using thiol-ene photopolymerization in miniemulsion was described. Allyl derivatives of phenylalanine as a functional monomer was synthesized and copolymerized with acrylic monomers via miniemulsion polymerization to produce NIP-NPs with approximately 74 nm number average particle diameter. FTIR and 1H-NMR analysis confirmed the synthesis of functional monomer. MIP-NPs were prepared in the existence of myoglobin as a template protein. Morphological investigations exhibited that the particle size of the MIP-NPs, increased compared to the corresponding NIPs and the mean particle diameter by number was measured as 141 nm with narrow distribution. NIP-NPs that were polymerized without myoglobin were found to have less affinity to the target protein. In addition, the rebinding ability of MIP-NPs was much bigger than that of the corresponding NIPs. ELISA results showed that MIPs interact particularly with the myoglobin and show little affinity for BSA in competitive binding experiments.HighlightsAllyl N,N-diallyl phenylalaninate was synthesized as a functional monomer.Imprinted nanoparticles were prepared by using thiol-ene photopolymerization in miniemulsion.The nanoparticles were 141 nm with narrow size distribution.The imprinted nanoparticles showed selectivity toward myoglobin.

Characterization of Resistance Genes and Polymerase Chain Reaction-Based Replicon Typing in Carbapenem-Resistant Klebsiella pneumoniae.

Background: Fifty isolates of Klebsiella pneumoniae isolated from clinical samples between 2012 and 2016 that were found to be resistant to carbapenems were included in this study. Materials and Methods: Resistance genes were investigated by performing PCR. Plasmid typing was performed using PCR-based replicon typing. The clonal relationships between the strains were investigated using pulsed-field gel electrophoresis (PFGE). Results: OXA-48-type carbapenemase genes were detected in 86% (n = 43/50) of K. pneumoniae isolates, whereas NDM-type carbapenemase genes were detected in 14% (n = 7/50) of the isolates. blaTEM was detected 60% (n = 30) of the strains, blaSHV in 78% (n = 39), blaCTX-M-1 in 48% (n = 24), and blaCTX-M-2-type ß-lactamase in 10% (n = 5). blaCTX-M-1 and blaSHV were concomitantly distributed in 40% (n = 20) of the strains, blaTEM and blaSHV in 54% (n = 27), blaTEM, blaSHV, and blaCTX-M-1 in 32% (n = 16) and blaCTX-M-1 and blaCTX-M-2 in 10% (n = 5). Strain numbers 66, 69, 76, 77, and 78 coproduced carbapenemases, blaCTX-M-1 and blaCTX-M-2 in addition to blaOXA-48 or blaNDM-1 that were described as hybrid strains. IncR-type replicon was found in 50% (n = 25) of 50 isolates with plasmid typing, whereas IncA/C-type replicon was detected in 40% (n = 20) and IncFIIK-type replicon in 18% (n = 9) of the isolates. Outcomes of the transformation experiments showed that the OXA-48 gene was carried to the receiver cell on FII plasmids. No dominant epidemic clone was detected through PFGE. Conclusion: OXA-48 carbapenemase was found to be the most prevalent type of enzyme in our hospital, and the presence of NDM-1-type carbapenemase-carrying strain and an increase in their rate were detected.

Effect of N-acetyl cysteine, rifampicin, and ozone on biofilm formation in pan-resistant Klebsiella pneumoniae: an experimental study

ABSTRACT BACKGROUND: To the best of our knowledge, this is the first study to evaluate the effectiveness of specific concentrations of antibiofilm agents, such as N-acetyl cysteine (NAC), rifampicin, and ozone, for the treatment of pan-resistant Klebsiella pneumoniae (PRKp). OBJECTIVES: We evaluated the effectiveness of antibiofilm agents, such as NAC, rifampicin, and ozone, on biofilm formation in PRKp at 2, 6, 24, and 72 h. DESIGN AND SETTING: This single-center experimental study was conducted on June 15, 2017, and July 15, 2018, at Istanbul Faculty of Medicine, Istanbul University, Turkey. METHODS: Biofilm formation and the efficacy of these agents on the biofilm layer were demonstrated using colony counting and laser-screened confocal microscopy. RESULTS: NAC at a final concentration of 2 μg/mL was administered to bacteria that formed biofilms (24 h), and no significant decrease was detected in the bacterial counts of all isolates (all P > 0.05). Rifampicin with a final concentration of 0.1 μg/mL was administered to bacteria that formed biofilm (24 h), and no significant decrease was detected in bacterial count (all P > 0.05). Notably, ozonated water of even 4.78 mg/L concentration for 72 h decreased the bacterial count by ≥ 2 log10. CONCLUSION: Different approaches are needed for treating PRKp isolates. We demonstrate that PRKp isolates can be successfully treated with higher concentrations of ozone.