Efficacy of ceftazidime/avibactam and plazomicin on carbapenem-resistant Klebsiella pneumoniae and Escherichia coli.

Carbapenem-resistant Enterobacterales (CRE) have become a major public health problem worldwide. The aim of this study was to investigate efficacy of ceftazidime/avibactam and plazomicin on carbapenem-resistant Klebsiella pneumoniae and Escherichia coli isolates. Susceptibility of imipenem, meropenem, ertapenem, ceftazidime/avibactam and plazomicin was investigated by broth-microdilution method. Major carbapenemases NDM, VIM, IMP, KPC, OXA-48 as well as other ß-lactamases namely, TEM, SHV, OXA-1-like, CTX-M, ACC, FOX, MOX, DHA, CIT, EBC, VEB, GES, PER were investigated by PCR. A total of 120 carbapenem-resistant isolates (60 E. coli and 60 K. pneumoniae) were included in this study and blaOXA-48-like was found in 78.33%, blaNDM in 26.66%, blaKPC in 7.5%, blaIMP in 5.83%, and blaVIM in 5%. Among 94 isolates with the blaOXA-48-like gene, 22.3% were resistant to ceftazidime/avibactam and 51.1% were resistant to plazomicin. Of 32 isolates with blaNDM, 31 (96.9%) were resistant to ceftazidime/avibactam and 30 (93.75%) were resistant to plazomicin, and both antibiotics had limited effects against blaNDM carriers (P < 0.001). Of the 12 isolates with blaNDM+OXA-48 combination, 11 (91.7%) were resistant to ceftazidime/avibactam and plazomicin. The effect of both antibiotics was significantly lower in strains with blaNDM+OXA-48 combination (P < 0.005).The most common carbapenemase genes in this study were blaOXA-48-like and blaNDM. Ceftazidime/avibactam demonstrated a good efficacy among OXA-48 producing K. pneumoniae and E. coli, however, plazomicin had a significantly lower antibacterial effect in our study. Both antimicrobial agents should be considered as an option by evaluating combined susceptibility results and gene patterns obtained by regional and global molecular data in the treatment of CRE infections.

Distribution of virulence determinants among Escherichia coli ST131 and its H30/H30-Rx subclones in Turkey.

Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading pathogen in urinary tract infection. In recent years multidrug-resistant B2-ST131 E. coli clonal group has disseminated worldwide. The ST131 and its subclones H30 and H30-Rx have been identified only in a few studies from Turkey. The aim of this study is to investigate the presence of ST131 and its subclones and to analyze their adhesin virulence genes and antimicrobial resistance. A total of 250 urinary ExPEC isolates were included in the study. Resistance rates of 16 antimicrobial agents were determined by disk-diffusion. Multidrug-resistance and ESBL production were analyzed. Altogether 8 adhesin genes were investigated namely, papAH, fimH, sfa/focDE, focG, afa/draBC, iha, bmaE and gafD. A total of 39 ST131 isolate were determined and 33 (84.6%) were multidrug-resistant. ESBL production was detected in 34 (87.2%) ST131 and 61 (28.9%) of non-ST131 strains. In our study, we found a strong correlation between ST131 strains and fimH, iha, afa/draBC, papAH virulence determinants. Twenty-nine (85.3%) of 34 ST131-O25b-H30 isolates were identified as H30-Rx. All the papAH gene positive isolates were identified within ST131-O25b-H30-Rx lineage. Non-H30-Rx isolates within H30 isolates were identified as pattern 2. Almost 16% of the isolates were identified as ST131 regardless of clinical syndrome and approximately 34% of the multidrug-resistant isolates were H30-Rx subclone. We report H30-Rx as the dominant subclone of ST131 in our study. Imipenem, fosfomycin and nitrofurantoin proved to be the most effective agents according to antibiotic resistance patterns of both ST131 and non-ST131 E. coli strains.

In-vitro activities of imipenem-colistin, imipenem-tigecycline, and tigecycline-colistin combinations against carbapenem-resistant Enterobacteriaceae.

The aim of the study is to determine in-vitro effects of imipenem-tigecycline, imipenem-colistin and tigecycline-colistin against carbapenem-resistant Enterobacteriaceae (CRE) isolates. A total of 25 CRE isolates were included to the study. The minimum inhibition concentrations of imipenem, colistin-sulphate and tigecycline were determined with broth dilution method. Synergistic effects of imipenem-tigecycline, imipenem-colistin and tigecycline-colistin were investigated by microdilution checkerboard technique. All of the isolates were resistant to imipenem, whereas 25% of the isolates were resistant to colistin and tigecycline. Imipenem-colistin, imipenem-tigecycline and tigecycline-colistin combinations were synergistic against 40% (10/25), 24% (6/25), and 36% (9/25) of the isolates, respectively. Antagonism was observed in 8% (2/25) of the isolates in tigecycline-colistin combination. Tigecycline-colistin was the most effective (70% synergy) combination in Klebsiella spp. strains; whereas imipenem-colistin was the most effective (75% synergy) combination in Escherichia coli strains. Synergistic effect was variable and strain-depended against CRE isolates that have been tested.

High Infection-Related Mortality in Pediatric Acute Myeloid Leukemia without Preventive Antibiotics and Antifungals: Retrospective Cohort Study of a Single Center from a Middle-Income Country.

OBJECTIVE: This study aimed to evaluate infection-related mortality in patients with acute myeloid leukemia (AML) treated without preventive antibiotics and antifungals in a middle-income country. MATERIALS AND METHODS: Infection-related mortality was evaluated retrospectively in 49 pediatric patients. RESULTS: A total of 173 chemotherapy courses were administered as first-line chemotherapy. Four patients died during induction: one patient due to intracranial bleeding, two patients due to typhlitis, and one patient due to invasive fungal infection with pulmonary vascular invasion and massive bleeding. Another two patients died with resistant disease. During consolidation there were four infection-related deaths and one death due to cardiotoxicity. In first-line chemotherapy mortality was 22% (11/49); infection-related mortality was 14% (7/49). Event-free survival and overall survival at 6 years were 42.9% and 61.2% (95% CI: 44-76 and 66-99 months), respectively. CONCLUSION: Due to considerable infection-related deaths, antibacterial and mold-active antifungal prophylaxis may be tried during neutropenic periods in pediatric AML.

Childhood urinary tract infection caused by extended-spectrum ß-lactamase-producing bacteria: Risk factors and empiric therapy.

BACKGROUND: This study investigated risk factors of childhood urinary tract infection (UTI) associated with extended-spectrum ß-lactamase (ESBL)-producing bacteria (ESBL-positive UTI) and evaluated antimicrobial resistance as well as empiric treatment of childhood UTI. METHODS: The records of children with positive urine culture between 1 January 2008 and 31 December 2012 were evaluated. Patients with positive urine culture for ESBL-producing bacteria were defined as the ESBL-positive group, whereas patients of the same gender and similar age with positive urine culture for non-ESBL-producing bacteria were defined as the ESBL-negative group. Each ESBL-positive patient was matched with two ESBL-negative patients. RESULTS: The ESBL-positive and negative groups consisted of 154 and 308 patients, respectively. Potential risk factors for ESBL-positive UTI were identified as presence of underlying disease, clean intermittent catheterization (CIC), hospitalization, use of any antibiotic and history of infection in the last 3 months (P < 0.05). On logistic regression analysis, CIC, hospitalization and history of infection in the last 3 months were identified as independent risk factors. In the present study, 324 of 462 patients had empiric therapy. Empiric therapy was inappropriate in 90.3% of the ESBL-positive group and in 4.5% of the ESBL-negative group. Resistance to nitrofurantoin was similar between groups (5.1% vs 1.2%, P = 0.072); resistance to amikacin was low in the ESBL-positive group (2.6%) and there was no resistance in the ESBL-negative group. CONCLUSIONS: Clean intermittent catheterization, hospitalization and history of infection in the last 3 months should be considered as risk factors for ESBL-positive UTI. The combination of ampicillin plus amikacin should be taken into consideration for empiric therapy in patients with acute pyelonephritis who have the risk factors for ESBL-positive UTI. Nitrofurantoin seems to be a logical choice for the empiric therapy of cystitis.

Epidemiological and molecular characteristics of meticillin-resistant Staphylococcus aureus in Turkey: A multicentre study.

The aim of this study was to investigate the epidemiological and molecular features of clinical meticillin-resistant Staphylococcus aureus (MRSA) isolates in Turkey. MRSA isolates were collected from six regions of Turkey. The mecA and nuc genes were detected by PCR. Antimicrobial susceptibilities were determined by the disk diffusion method. Staphylococcal cassette chromosome mec (SCCmec) and staphylococcal protein A (spa) typing were performed by the sequencing method for 270 randomly selected MRSA isolates. The US Centers for Disease Control and Prevention (CDC) definition was used for epidemiological diagnosis of community-associated MRSA (CA-MRSA). Resistance rates of MRSA to ciprofloxacin, gentamicin, clindamycin, erythromycin, rifampicin, trimethoprim/sulfamethoxazole and tetracycline were 93.4%, 81.2%, 38.5%, 57.8%, 93.9%, 1.1% and 93.1%, respectively. The most frequent SCCmec type was SCCmec III (91.1%). SCCmec type IV was found in 5.2% of the isolates. The most frequent spa type was t030 (81.1%). Five isolates were CA-MRSA if only the epidemiological definition was used (5/725; 0.7%). Two isolates were defined as CA-MRSA both by epidemiological features and SCCmec typing (2/270; 0.7%). Of 14 SCCmec type IV isolates, 12 were not defined as CA-MRSA by epidemiological features. In conclusion, this is the most comprehensive multicentre study in Turkey investigating MRSA using both epidemiological and genotypic features. The CA-MRSA rate is low in Turkey. Combined use of epidemiological and genotypic methods is the most accurate approach for the diagnosis of CA-MRSA.

[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.

Comparison of Vitek Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Versus Conventional Methods in Candida Identification.

Candida species are generally identified by conventional methods such as germ tube or morphological appearance on corn meal agar, biochemical methods using API kits and molecular biological methods. Alternative to these methods, rapid and accurate identification methods of microorganisms called matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been described. In this study, Candida identification results by API Candida kit, API 20C AUX kit and identifications on corn meal agar (CMA) are compared with the results obtained on Vitek-MS. All results were confirmed by sequencing internal transcribed spacer (ITS) regions of rDNA. Totally, 97 Candida strains were identified by germ tube test, CMA, API and Vitek-MS. Vitek-MS results were compatible with 74.2 % of API 20C AUX and 81.4 % of CMA results. The difference between the results of API Candida and API 20C AUX was detected. The ratio of discrepancy between Vitek-MS and API 20C AUX was 25.8 %. Candida species mostly identified as C. famata or C. tropicalis by and not compatible with API kits were identified as C. albicans by Vitek-MS. Sixteen Candida species having discrepant results with Vitek-MS, API or CMA were randomly chosen, and ITS sequence analysis was performed. The results of sequencing were compatible 56.2 % with API 20C AUX, 50 % with CMA and 93.7 % with Vitek-MS. When compared with conventional identification methods, MS results are more reliable and rapid for Candida identification. MS system may be used as routine identification method in clinical microbiology laboratories.

Relationship between phylogenetic groups, antibiotic resistance and patient characteristics in terms of adhesin genes in cystitis and pyelonephritis isolates of Escherichia coli.

Extraintestinal pathogenic Escherichia coli (E. coli) is considered as the main causative agent of urinary tract infections worldwide. The relationship between antimicrobial resistance, phylogenetic groups, patient characteristics and adhesin virulence genes are complex and not fully understood. In this study, among 146 urinary isolates of E. coli, phylogenetic groups and various adhesin virulence genes were examined with multiplex Polymerase Chain Reaction methods. Patient characteristics divided into sex, cystitis and pyelonephritis; community-acquired and hospital-acquired; complicated and uncomplicated infection. Antimicrobial resistance was also determined. The papAH gene was seen more often in pyelonephritis than cystitis and female than male patients. iha gene was more frequent in hospital-acquired infections than in community-acquired infections. sfa/focDE was more frequent in ampicillin, amikacin, gentamicin, nalidixic acid, norfloxacin, cefuroxime, ceftriaxone, cefazolin, cefotaxime, ciprofloxacin and trimethoprim/sulfamethoxazole susceptible and extended-spectrum ß-lactamase (ESBL) and multi-drug resistance (MDR) negative isolates. focG was seen more often in nalidixic acid, norfloxacin, cefuroxime, ceftriaxone, ciprofloxacin susceptible and MDR negative isolates. fimH and papAH were more commonly observed in amoxicillin/clavulanic acid and cefotaxime susceptible isolates, respectively. iha and afa/draBC genes were more frequent in resistant isolates than the susceptible ones; for iha, in ampicillin, amoxicillin/clavulanic acid, nalidixic acid, cefuroxime, ceftriaxone resistant and ESBL and MDR positive isolates; for afa/draBC, in cefotaxime, cefuroxime, ciprofloxacin, trimethoprim/sulfamethoxazole resistant and ESBL and MDR positive isolates, this trend was observed. ST 131 E. coli virulence gene pattern has a direct effect on resistance profile. Isolates belong to that clonal group has MDR and commonly harbour afa/draBC and iha genes. Our findings may provide new insights into the relationships between pathogenesis, patient characteristics and resistance of E. coli UTI.

Evaluation of immunochromatographic test for the detection of antibodies against Echinococcosis granulosus.

BACKGROUND: Echinococcosis in humans is a disease caused by the larvae of Echinococcus granulosus (E. granulosus) and Echinococcus multilocularis (E. multilocularis). Serological tests are valuable, especially in the clarification of unexplained clinical findings and imaging methods. For this reason, indirect hemagglutination (IHA), latex agglutination, immunoelectrophoresis, immunoblotting, immuno-enzymatic tests, indirect fluorescence antibody test (IFAT), and enzyme-linked immunosorbent assay (ELISA) are used. The purpose of this study was to investigate the value of an immunochromatographic test (ICT) specific for E. granulosus antibodies in the diagnosis of echinococcosis. MATERIAL/METHODS: ICT evaluated 102 cases of cystic echinococcosis, 38 cases of other parasitic diseases, and 50 healthy individuals. ELISA (DRG, Germany) that detects IgG antibodies specific for E. granulosus was used as the reference method. RESULTS: The sensitivity, specificity, and positive and negative predictive values of ICT were 96.8%, 87.5%, 98.9%, and 70%, respectively. Diagnostic value was 96.1%. No significant differences and high degrees of agreement were found between ELISA and immunochromatographic test for cystic echinococcosis. Serum samples included 4 taeniasis, 2 leishmaniasis, and 2 healthy individuals were diagnosed to be positive with immunochromatographic test. CONCLUSIONS: The ability of test to give fast results without need for equipment, devices, and specific storage conditions is an advantage. This test may be used due to its advantages in endemic regions for screening and diagnostic purposes.

Do the interactions between coital frequency, cervical length, and urogenital infection affect obstetric outcomes?

OBJECTIVE: To determine whether interactions between coital frequency, cervical length, and urogenital infection affect obstetric outcomes. MATERIALS AND METHODS: A total of 268 unselected pregnant women were recruited in the study. The study population consisted of four groups of women: group 1 (n=203) screened negative for bacterial vaginosis (BV) both in the first and second trimesters; group 2 (n=18) screened negative for BV in the first trimester but positive in the second trimester; group 3 (n=33) screened positive for BV in the first trimester but negative in the second trimester; and group 4 (n=14) screened positive for BV both in the first and second trimesters. Urine culture, cervico-vaginal cultures, and bacterial vaginosis were screened between 11-14 weeks and 20-24 weeks. RESULTS: Two hundred fifty women were eligible for analysis in the study after lost-to-follow up patients were excluded. Previous abortion ≥1 and previous preterm delivery at 24-34 weeks ≥1 were statistically significantly higher in group 2. The number of patients who were diagnosed as having preterm premature rupture of membranes (PPROM) was statistically significantly higher in group 4. Sexual intercourse during the first trimester, cervical length during the second trimester, and history of preterm birth (PTB) were statistically significant risk factors for preterm birth <37 weeks (1.27; (1.12-1.44); 5.33; (1.84-15.41); 6.95; (1.58-30.54), respectively). CONCLUSION: Presence or treatment of BV did not influence rates of PTB. The probability of PPROM would be higher in patients who are BV positive both in the first and second trimesters.

Phosphorus-nitrogen compounds. Part 29. Syntheses, crystal structures, spectroscopic and stereogenic properties, electrochemical investigations, antituberculosis, antimicrobial and cytotoxic activities and DNA interactions of ansa-spiro-ansa cyclotetraphosphazenes.

A number of novel ansa-spiro-ansa (asa) cyclotetraphosphazenes (1a-5b) was prepared in the range of 63-90 % yields. The structures of the compounds were verified by MS, FTIR, (1)H, (13)C{(1)H} and (31)P{(1)H} NMR, heteronuclear single quantum coherence (HSQC), and heteronuclear multiple-bond correlation (HMBC) techniques. The crystal structures of 1b, 2c and 5a were determined by X-ray crystallography. The compound 2c was analyzed by the changes in the (31)P{(1)H}NMR spectrum in addition of the chiral solvating agent; (R)-(+)-2,2,2-trifluoro-1-(9'-anthryl)-ethanol (CSA), to investigate its stereogenic properties. The result supports that compound 2c was found to be in the racemic mixture. Cyclic voltammetric and chronoamperometric data of the mono-ferrocenyl-spiro-asa-cyclotetraphosphazenes exhibited electrochemically reversible one-electron oxidation of Fe redox centres. The mono-ferrocenyl-spiro-asa compounds (3a-5b) were evaluated for antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv and M. tuberculosis clinical strain, which is resistant to rifampicin and isoniazid. These compounds appear not to be good candidates for being antituberculosis agents to clinical strains. All of the compounds were screened for antibacterial activities against G(+) and G(-) bacteria, and for antifungal activities against yeast strains. They seem to be more active against Gram positive bacteria than Gram negative. The interactions of the phosphazenes with plasmid DNA and the evaluations for cytotoxic activity against MCF-7 breast cancer cell lines were investigated. The compounds 1b, 2b, 3a and 4a were found to be more effective than Cisplatin against MCF-7 breast cancer cell lines at lower concentrations.

Vancomycin and daptomycin minimum inhibitory concentration distribution and occurrence of heteroresistance among methicillin-resistant Staphylococcus aureus blood isolates in Turkey.

BACKGROUND: The aim of this study was to determine the distribution of vancomycin and daptomycin MICs among methicillin-resistant Staphylococcus aureus (MRSA) blood isolates, the prevalence of heterogeneous vancomycin-intermediate S. aureus (hVISA) and the relationship between hVISA and vancomycin MIC values. METHODS: A total of 175 MRSA blood isolates were collected from seven university hospitals in Turkey. All isolates were tested for susceptibility to vancomycin and daptomycin by reference broth microdilution (BMD) and by standard Etest method. BMD test was performed according to CLSI guidelines and Etest was performed according to the instructions of the manufacturer. All isolates were screened for the presence of the hVISA by using macro Etest (MET) and population analysis profile-area under the curve (PAP-AUC) methods. RESULTS: The vancomycin MIC50, MIC90 and MIC ranges were 1, 2, and 0.5-2 µg/ml, respectively, by both of BMD and Etest. The daptomycin MIC50, MIC90 and MIC ranges were 0.5, 1 and 0.125 -1 µg/ml by BMD and 0.25, 0.5 and 0.06-1 µg/ml by Etest, respectively. The vancomycin MIC for 40.6% (71/175) of the MRSA isolates tested was >1 µg/ml by BMD. No vancomycin and daptomycin resistance was found among MRSA isolates. Percent agreement of Etest MICs with BMD MICs within ±1 doubling dilution was 100% and 73.1% for vancomycin and daptomycin, respectively. The prevalence of hVISA among MRSA blood isolates was 13.7% (24/175) by PAP-AUC method. MET identified only 14 of the hVISA strains (sensitivity, 58.3%), and there were 12 strains identified as hVISA that were not subsequently confirmed by PAP-AUC (specificity, 92.1%). CONCLUSIONS: Agreement between BMD and Etest MICs is high both for vancomycin and daptomycin. Daptomycin was found to be highly active against MRSA isolates including hVISA. A considerable number of isolates are determined as hVISA among blood isolates. As it is impractical to use the reference method (PAP-AUC) for large numbers of isolates, laboratory methods for rapid and accurate identification of hVISA need to be developed.

OXA-162, a novel variant of OXA-48 displays extended hydrolytic activity towards imipenem, meropenem and doripenem.

CONTEXT: Isolation and characterization of OXA-162, a novel variant of OXA-48. OBJECTIVES: Klebsiella pneumoniae isolate with decreased susceptibility to carbapenems was recovered from a Turkish patient. This study aimed at characterizing the carbapenem resistance determinants of this isolate. MATERIALS AND METHODS: Antibiotic susceptibility tests, analytic isoelectric focusing (IEF), cloning and sequencing were performed. Cloned ß-lactamase was purified by means of preparative gel electrophoresis and the kinetic constants were determined under initial rate conditions. RESULTS: The identified bla(OXA-162) gene was located on a ca. 45-kb plasmid carrying a transposon consisted of two IS1999-2 elements. OXA-162 differed from OXA-48 by a single amino acid substitution (Thr213Ala) which increased the catalytic efficiency (k(cat)/K(M)) of OXA-162 towards imipenem and meropenem. Also this substitution caused a gain of hydrolysis ability towards doripenem. Analysis of OXA-162 model implied that the amino acid change might generate an extension in the opening of the substrate entry site and might cause extended hydrolytic activity towards imipenem, meropenem and doripenem. DISCUSSION AND CONCLUSION: OXA-162, a derivative of OXA-48 has enhanced catalytic properties.

[Anti-candidal activity of clinical Pseudomonas aeruginosa strains and in vitro inhibition of Candida biofilm formation]. / Klinik Pseudomonas aeruginosa Suslarinin Antikandidal Aktiviteleri ve In Vitro Candida Biyofilm Olusumunun Inhibisyonu.

It has been shown recently that signal-mediated interactions between the opportunistic pathogens Pseudomonas aeruginosa and Candida albicans affect virulence features in both organisms. It has been emphasized that the anti-candidal activity of P.aeruginosa is especially due to its pyocyanin pigment. The structure and the properties of monospecies biofilms and their role in infectious disease have been extensively studied. However, there are only few studies on interactions between P.aeruginosa ve Candida spp. In mixed biofilms. Therefore, in this study, the investigation of anti-candidal activity of P.aeruginosa against Candida spp. And the effect on C.albicans biofilm were aimed. A total of 58 P.aeruginosa strains isolated from several clinical specimens and one of each C.albicans ATCC 90028, C.parapsilosis ATCC 22019, C.glabrata ATCC 90030 and a C.tropicalis clinical isolate were included in the study. The anti-candidal activity of P.aeruginosa strains were investigated on Sabouraud dextrose agar using Kerr's method. The absence of the growth of Candida strains were evaluated as total inhibition. The effect of two P.aeruginosa strains showing total inhibition and one isolate without inhibition effect on C.albicans biofilm was investigated by microplate method. For the evaluation of monospecies or mixed species biofilms of Pseudomonas and C.albicans, the number of colony forming units (cfu/ml) after 90 minutes (adhesion phase), 24 hours and 48 hours (biofilm phase) incubation were determined. Then, cfu numbers of monospecies and mixed species of Pseudomonas and C.albicans were compared. Total inhibition rates of Pseudomonas strains against C.albicans, C.tropicalis, C.glabrata and C.parapsilosis were determined as 63.8%, 75.9%, 65.5% and 72.4%, respectively. A significant reduction was determined in cfu/ml numbers of mixed species of Pseudomonas and C.albicans compared to cfu numbers in monospecies biofilm after 90 minutes, 24 hours and 48 hours (p< 0.05). In addition to the inhibitory effect of P.aeruginosa on Candida growth, in a dual species environment both organisms mutually suppressed each others' biofilm development quantitatively. These findings indicated that molecular basis of signal-mediated interaction between Pseudomonas and Candida spp. Should be clarified for better understanding of the pathogenesis of mixed bacterial-fungal infections.

Macrolide and tetracycline resistance and emm type distribution of Streptococcus pyogenes isolates recovered from Turkish patients.

The aims of this study were to determine the susceptibilities to macrolide and tetracycline antibiotics and emm type distribution of Streptococcus pyogenes strains isolated in the Kocaeli University Hospital, Turkey. A total of 127 S. pyogenes clinical isolates were tested. Eleven (9%) isolates were resistant to erythromycin, and 23 (18%) isolates were resistant to tetracycline. Ten of the erythromycin-resistant isolates were also resistant to tetracycline. By the triple-disk test, all erythromycin-resistant isolates showed the inducible macrolide-lincosamide-streptogramin-C phenotype and harbored erm(TR) gene. tet(O) was the most common tetracycline resistance gene. Among erythromycin-tetracycline coresistant isolates, seven harbored the tet(O) gene. emm 4, emm 1, emm 2,114, and emm 89 were the most common emm types. These isolates were more susceptible to erythromycin. There was considerable emm type heterogeneity in macrolide or tetracycline resistant isolates. According to our knowledge, this is the first study in which emm type distribution is investigated in Turkey. More comprehensive studies are needed to obtain true information about the epidemiology of macrolide and tetracycline resistance and emm type distribution in Turkey.

[Comparison of broth microdilution and E-test methods for the antifungal susceptibility testing of Candida spp. strains isolated from blood cultures]. / Kan kültürlerinden izole edilen Candida spp. suslarinin antifungal ilaçlara karsi duyarliliklarinin belirlenmesinde buyyon mikrodilüsyon ile E-test yöntemlerinin karsilastirilmasi.

The incidence of serious fungal infections, particularly invasive Candida infections exhibit an increasing trend in the last decades since the number of patients receiving immunosuppressive treatment is increasing. This situation eventually results in an increment in resistance to antifungal agents. The aim of this study was to compare the standard broth microdilution (BMD) and E-test methods for antifungal susceptibility testing of Candida species isolated from blood cultures in our hospital, against fluconazole, voriconazole, caspofungin and amphotericin B. A total of 46 Candida strains isolated from the blood cultures by BACTEC 9000 (Becton Dickinson, USA) and identified by conventional techniques and API 20C AUX (BioMerieux, France) during January 2006-December 2007, were included into this study. The identification results of the isolates were as follows: C. albicans (23), C. parapsilosis (10), C. tropicalis (5), C. krusei (3), C. famata (2), C. glabrata (1), C. guilliermondii (1), C. kefyr (1). The antifungal susceptibilities were determined by BMD method described in Clinical and Laboratory Standards Institute M27-A3 document and E-test. Only two isolates (C. albicans and C. globrata) were found to be resistant to fluconazole with E-test but susceptible with BMD. The minimal inhibitory concentration (MIC) values of caspofungin were higher (MIC = 1-2 microg/ml) in C. parapsilosis compared to other Candida species using E-test. Only one C. albicans was resistant to voriconazole by E-test (MIC = 4 microg/ml), but it was susceptible by BMD (MIC = 0.08 microg/ml). Since definite resistance breakpoints do not yet exist for amphotericin B, MIC values were considered for amphotericin B and it was found that all strains had identical low MIC values (< 0.002-0.5). When E-test results were compared with the standard BMD results, MIC values were in agreement 80.4% for fluconazole, 84.7% for amphotericin B, 95.6% for voriconazole and 93.4% for caspofungin. These results indicated that the most frequently isolated Candida species among blood cultures was C. albicans, followed by C. parapsilosis and these isolates had low antifungal resistance rates. When voriconazol and caspofungin susceptibilities were considered, both E-test and BMD susceptibility results were in good aggreement in comparison to fluconazol and amphotericin B. E-test can be considered as a compatible method for the antifungal susceptibility testing of Candida species compared to standard broth microdilution method.

Routine using pattern and performance of diagnostic tests for tuberculosis on a university hospital.

INTRODUCTION: Nucleic acid amplification tests to detect Mycobacterium tuberculosis in clinical specimens are used increasingly as a laboratory tool. We aimed to investigate the routine using pattern and the effects on therapeutic decision of diagnostic tests for tuberculosis in our hospital. METHODS: In this descriptive study, we investigated retrospectively the routine using pattern and the effects on therapeutic decision of diagnostic tests for tuberculosis. Patients with discordant results were clinically evaluated retrospectively by a chest physician. Samples were tested for the presence of M. tuberculosis by a smear technique, M. tuberculosis culture growth technique (Löwenstein-Jensen and/or BACTEC-960), and IS6110 polymerase chain reaction (PCR). RESULTS: Culture positivity was 7.2% (83 of 1159 patients). In total, 198 (62.4%) were tested with PCR, acid-fast bacilli, and culture. On the basis of culture results as a gold standard, sensitivity, specificity, positive predictive value, and negative predictive value of PCR were 46%, 89%, 23%, and 93.5%, respectively. CONCLUSIONS: Selection of appropriate patients for further testing and exclusion of low-risk patients from microbiologic testing by experienced clinicians may help to optimize the positive predictive value of PCR.

In-vitro efficacy of synergistic antibiotic combinations in multidrug resistant Pseudomonas aeruginosa strains.

PURPOSE: Combination antibiotic treatment is preferred in nosocomial infections caused by Pseudomonas aeruginosa (P. aeruginosa). In vitro synergism tests were used to choose the combinations which might be used in clinic. The aim of this study was to investigate the synergistic efficacy of synergistic antibiotic combinations in multidrug resistant P. aeruginosa strains. MATERIALS AND METHODS: Synergistic efficacies of ceftazidime-tobramycin, piperacillin/tazobactam-tobramycin, imipenem-tobramycin, imipenem-isepamycin, imipenem-ciprofloxacin and ciprofloxacin-tobramycin combinations were investigated by checkerboard technique in 12 multiple-resistant and 13 susceptible P. aeruginosa strains. RESULTS: The ratios of synergy were observed in ceftazidime-tobramycin and piperacillin/tazobactam-tobramycin combinations as 67%, and 50%, respectively, in resistant strains, whereas synergy was not detected in other combinations. The ratios of synergy were observed in ceftazidime-tobramycin, piperacillin/tazobactam-tobramycin, imipenem-tobramycin, imipenem-ciprofloxacin and imipenem-isepamycin combinations as 31%, 46%, 15%, 8%, 8%, and respectively, in susceptible strains, whereas synergy was not detected in ciprofloxacin-tobramycin combination. Antagonism was not observed in any of the combinations. CONCLUSION: Although the synergistic ratios were high in combinations with ceftazidime or piperacillin/tazobactam and tobramycin, the concentrations in these combinations could not usually reach clinically available levels. Thus, the solution of the problems caused by multiple resistant P. aeruginosa should be based on the prevention of the development of resistance and spread of the causative agent between patients.

Pseudo-outbreak of Serratia marcescens in a tertiary care hospital.

The aim of this study was to describe a pseudo-outbreak due to Serratia marcescens associated with laboratory contamination, and also the epidemiologic and laboratory methods used to determine the source of contamination. An apparent increase in positive culture results for Serratia marcescens was observed in the Clinical Microbiology Laboratory of Kocaeli University Hospital between September and November 2007. An outbreak investigation including retrospective and prospective studies using chart review, environmental sampling and random arbitrary polymorphic DNA-polymerase chain reaction (RAPD-PCR) of randomly selected isolates were performed by the Infection Control Committee. Nine out of 67 strains belonged to a real infection. S. marcescens was also isolated from saline solution in the specimen processing area of the laboratory. It was recognized that the technician has been using the same stock saline solution for processing specimens without changing the injector. RAPD patterns of the clinical isolates were identical to the pattern of saline strain. The contaminated saline solution was discarded, the technician was trained and no additional cases of suspected contamination have been observed. This pseudo-outbreak emphasize the importance of the observation of specimen processing procedures and the training of laboratory workers.