Identification of root canal microbiota profiles of periapical tissue diseases using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

OBJECTIVES: The purpose of this study was to identify microorganisms isolated from various periapical tissue diseases using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) and classify them via an unsupervised machine learning approach. METHODS: A total of 150 patients with various apical conditions and teeth in need of endodontic retreatment were divided into five groups, including Retreatment, Acute Apical Abscess, Chronic Apical Abscess, Acute Apical Periodontitis, and Chronic Apical Periodontitis. Samples were collected from root canals using paper points after agitating with a #10 K file then microorganisms were identified using MALDI-TOF-MS. Data were analyzed using a hierarchical clustering method. Quadruple clusters and dendrograms were formed according to similarities and dissimilarities. RESULTS: A total of 80 species were identified representative of six different phyla. The most similar microorganism species identified were: ''Enterococcus faecalis'' between 21 and 23-year-old female cases in Retreatment group; ''Lactobacillus rhamnosus'' between 20 and 18-year-old male cases in Symptomatic Apical Abscess cases; ''Lactobacillus paracasei'' between 26 and 40-year-old male cases in Asymptomatic Apical Abscess cases; ''Enterococcus faecalis'' between 48 and 50-year-old female cases in Symptomatic Apical Periodontitis cases; ''Lactobacillus rhamnosus'' between 48 and 60-year-old male cases in Asymptomatic Apical Periodontitis cases. CONCLUSIONS: MALDI-TOF MS can be considered a fast and high-throughput screening technique for microbial species identification in endodontics. Thus, it will provide valuable data for future research designs regarding periapical tissue diseases. As the MALDI-TOF MS database expands and comprehensive data becomes available, the relationship between microbial profiles and disease progression will become increasingly apparent.

Prevalence and Quantity of Parvovirus B19 DNA Among Blood Donors from a Regional Blood Center in Turkey.

OBJECTIVE: Parvovirus B19 causes a range of diseases and morbidity in humans and is transmissible by transfusion of blood, blood components and plasma derivatives. The objective of the study was to investigate the prevalence and quantity of B19 DNA among blood donors. METHOD: Totally 1053 samples were collected from March to July 2016 at a blood bank for detection of Parvovirus B19 DNA and serological status of blood donors. Testing of the presence of viral DNA was performed by a quantitative real-time PCR with a 101 copies/ml detection limit. All DNA positive and randomly selected 267 samples were tested for the presence of anti-B19 IgM and IgG by ELISA. RESULTS: Age distribution of donors was between 18-64; mean age was 27 and median was 23. Among the 1053 samples, 5 (0.47%) had PB19 DNA. All PB19 DNA positive donations had both B19 IgM and IgG antibodies. The DNA level for positive donations were between 0.9 × 102 to 3.1 × 104 copies/ml. IgG and IgM were present in 59.9% (160/267) and 0,74% (2/267) respectively among the healthy donors without PB19 DNA. CONCLUSION: Detected DNA concentration was less than 105 copies/ml. The presence of IgM in low level PB19 DNA positive donors may indicate that there might be a risk in transmission of PB19 to particularly immunosuppressed recipients. The clinical follow-up of blood donation with low level of PB19DNA should be considered to answer the questions about blood safety.

An Investigation into Bacterial Bloodstream Infections and Antibiotic Resistance Profiles in a Tertiary Hospital for a Ten-Year Period.

BACKGROUND: Bloodstream infections are one of the major causes of healthcare-associated morbidity and mortality. The present study aims to investigate the prevalence of the microorganisms isolated from blood cultures and to evaluate susceptibilities to antimicrobial agents in a tertiary center, Gulhane Training and Research Hospital, Ankara, Turkey. METHODS: Blood cultures (BCs) were incubated in BACTEC/9050 (Becton Dickinson, USA) (2007 - 2015) and BacT/ALERT (bio-Merieux, France) (2014 - 2016) automated systems. PhoenixTM 100 system (Becton Dickinson, USA) (2007 - 2014), MALDI-TOF MS (Bruker, USA) (2015 - 2016) and conventional techniques were used for the identification of isolated microorganisms. According to CLSI (2007 - 2014) and EUCAST (2015 - 2016) criteria, Kirby-Bauer disc diffusion method, PhoenixTM system, and broth microdilution were applied for antimicrobial susceptibility testing. Two five-year periods were statistically compared regarding antibiotic resistance. RESULTS: From the overall evaluated 31,380 BCs, 7,367 cultures (23.5%) were positive, excluding 503 BCs (6.4%), which were interpreted as contamination. Of 7,367 isolated microorganisms, 3,680 (50.0%) were gram-negative, 3,303 (44.8%) were gram-positive bacteria, and 384 (5.2%) were fungi. Coagulase-negative staphylococci (CoNS) were predominantly isolated (n = 2,075; 28.2%) among gram-positives. E.coli (n = 978; 13.3%) was the most frequently isolated gram-negative species. Between the first and the last five-year period, three genera (Enterococcus spp., Acinetobacter spp., Streptococcus spp.) showed significant differences when isolated, and only Enterococcus spp. showed increased isolation rates. In total, 90.3% of CoNS and 32% of S. aureus were methicillin-resistant. Only 75 strains of Enterococcus spp. (12.1%) were vancomycin-resistant. ESBL was detected in 40.6% of E. coli and 30.7% of Klebsiella spp. isolates. Carbapenem resistance showed a significant increase, particularly in K. pneumoniae (> 20%). CONCLUSIONS: The findings suggest that there was a threatening condition in antimicrobial resistance rates, especially for some antimicrobials between two periods. Although antimicrobial resistance is usually associated with MRSA, carbapenem resistance, ESBL, and VRE, the problem is far beyond these definitions, consisting of not just medicine, but also commercial companies, food industry, veterinarians, and other areas.

Rapid Identification of Klebsiella pneumoniae by Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and Detection of Meropenem Resistance by Flow Cytometric Assay.

BACKGROUND: The aim of this study was to develop a rapid detection method of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains both MALDI-TOF MS and flow cytometry (FCM). METHODS: A total of 174 K. pneumoniae strains were included in this study. Molecular characterization of carbapenemase gene was performed by PCR. Bacterial identification was performed by MALDI-TOF-MS. Meropenem susceptibility was tested at the concentrations of breakpoints described by the Clinical and Laboratory Standards Institute (CLSI) guide by FCM. RESULTS: Sixty-two CRKP were positive for at least one carbapenemase gene. A total of 174 K. pneumoniae isolates obtained from clinically relevant material were correctly identified by Bruker MALDI-TOF MS with log (score) >2.0. These results were 100% concordant with the Phoenix™ Automated Microbiology System (BD, MD) and conventional identification results. Based on the analysis of the receiver operating characteristic (ROC) curves, the best validity and sensitivity data were obtained with a cut-off value of 18.88% by FCM. The concordance, sensitivity, and specificity for FCM by the selected cut-off values were 99.4%, 98.9%, and 100%, respectively. CONCLUSIONS: We conclude that reliable results on bacterial identification and meropenem susceptibility test can be obtained within 2 hr combined by MALDI-TOF-MS and FCM.

[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.

[Investigation of the presence of mecC and Panton-Valentine leukocidin genes in Staphylococcus aureus strains isolated from clinical specimens during seven years period]. / Yedi yillik sürede klinik örneklerden izole edilen Staphylococcus aureus suslarinda mecC ve Panton-Valentine lökosidin gen varliginin arastirilmasi.

Detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) in clinical microbiology laboratories are important for the selection of appropriate treatment and obtaining epidemiological data. mecC gene, is a mecA homologue, showing almost 69% DNA similarity with the mecA gene and the encoded protein by this gene shows almost 63% similarity with the PBP2a/2' protein. Several studies indicated that mecC positive MRSA strains can be transmitted from the livestock to humans by cross contamination. Panton-Valentine leukocidin (PVL), a potent cytotoxin of S.aureus is also considered as an important virulence factor. The aim of this study was to determine the existence and prevalence of mecC and pvl genes among S.aureus strains isolated from clinical specimens. A total of 1700 S.aureus isolates including 1177 methicillin-susceptible S.aureus (MSSA) and 523 MRSA, isolated in our hospital between January 2007 to December 2014, were included in the study. The isolates were identified by both conventional methods and BD Phoenix automated system (BD Diagnostic Instrument Systems, USA). Antibiotic susceptibility testing was performed by Kirby-Bauer disk diffusion method with oxacillin (1 µg) and cefoxitin (30 µg) according to the CLSI standards. The presence of mecA gene was investigated by the use of real-time PCR, and the presence of pvl and mecC genes were detected by conventional PCR method. Among the patients, 44.6% (759/1700) were outpatients, 65.8% (1119/1700) were male and the mean age of of patients was 39.7 years. Of 1700 isolates evaluated in this study, 523 (30.7%) were positive for mecA gene, however all of them were negative for mecC gene. A total of 32 (1.8%) isolates were positive for pvl gene including 23 (1.9%) out of 1177 MSSA and nine (1.7%) out of 523 MRSA strains. Eighteen (56.2%) of the PVL-positive S.aureus strains were isolated from skin and soft tissue infections. The frequency of PVL detected in this study was similar to the data of previous studies in our country. To the best of our knowledge, this is the first study for the determination of the mecC in our country. Although the mecC gene positive S.aureus has not been detected in our study, it should be kept in mind that the regional epidemiological conditions can vary quickly. In conclusion, multicenter studies are needed for the screening of mecC gene including the animal isolates, in Turkey.

[Identification of staphylococci directly from positive blood culture bottles by MALDI-TOF MS system]. / Stafilokoklarin pozitif kan kültür siselerinden MALDI-TOF MS sistemi ile direkt olarak tanimlanmasi

Bloodstream infections are substantial causes of morbidity and mortality worldwide. Staphylococcus species are the most commonly isolated microorganisms from blood cultures in clinical microbiology laboratories. MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time- of- Flight Mass Spectrometry) system allows the identification of microorganisms directly from positive blood culture bottles. The aim of this study was to evaluate the MALDI-TOF MS system for the identification of staphylococci directly from the positive blood culture bottles which revealed the presence of gram-positive cocci by staining. A total of 96 positive blood culture bottles that yielded gram-positive cocci by Gram stain were evaluated. These blood cultures were obtained from 69 patients between December 2013-February 2014. Conventional methods and BD Phoenix™ automated bacterial identification system (Becton Dickinson, USA) were used for routine identification. The strains were also identified by real-time Taqman PCR (qPCR) which was considered as the reference method. In MALDI-TOF MS method, MALDI Sepsityper™ Kit was used for the bacterial identification and all measurements were carried out by using Microflex LT instrument and FlexControl 3.0 software (Bruker Daltonics, USA). Of 96 culture bottles positive for gram-positive cocci, 90 were correctly identified as staphylococci at genus level with all the three study methods (qPCR, BD Phoenix, Bruker MALDI-TOF MS). The other six samples were identified as Enterococcus faecium (n= 4) and Streptococcus pyogenes (n= 2) by both Phoenix and the MALDI-TOF systems. Of the 90 samples, 87 were identified at the species level (15 S.aureus, 33 S.epidermidis, 29 S.hominis, 10 S.haemolyticus) and three at the genus level by the reference qPCR method. When comparing the results obtained by qPCR and Bruker MALDI-TOF MS, incompatibility was detected for three isolates. Those isolates were identified as S.hominis by qPCR, however two of them were identified as S.haemolyticus and one as S.epidermidis by MALDI-TOF MS. Compared with real-time Taqman PCR it was detected that Bruker MALDI TOF MS was identified 100% of S.aureus to the genus and species level and 100% and 96.6% of coagulase-negative staphylococci (CNS) to the genus and species level, respectively. In conclusion, it was thought that Bruker MALDI TOF MS system may allow rapid and reliable identification of S.aureus and CNS directly from positive blood culture bottles compared with the routine methods used in the clinical microbiology laboratory.

Rapid detection of antimicrobial susceptibility of the Bacteroides fragilis group by flow cytometry: A preliminary study.

A total of nine Bacteroides fragilis group strains and B. fragilis ATCC 25285 were studied. Six antibiotics were used in the study. Broth dilution method was used for flow cytometry (FCM) analysis. Cell suspensions with antibiotics and antibiotic-free were stained with thiazole orange and propidium iodide (PI) to differentiate dead/live cells. The percentage of dead and live cells was calculated using FCM device. Cut-off values for antibiotics (26,7 %, 35,5 % and 30,2 % for meropenem, AMC and clindamycin, respectively) were calculated for dead/live cell differentiation. A common cut-off value was calculated for bactericidal and bacteriostatic (31,8 % and 25,7 % respectively). The PI staining ratios of the B. fragilis ATCC 25285 calculated in the MIC ranges for each antibiotic were under the cut-off values calculated with clinical isolates. The cut-off values we calculated are compatible with MBC rather than MIC values. The FCM method is one of the candidate methods for antimicrobial susceptibility testing.

[Comparison of culture and polymerase chain reaction methods for the detection of Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis in cerebrospinal fluids and middle ear effusions]. / Orta kulak efüzyonu ve beyin omurilik sivilarinda Haemophilus influenzae, Streptococcus pneumoniae ve Moraxella catarrhaulis'in saptanmasinda kültür ve polimeraz zincir reaksiyonu yöntemlerinin karsilastirilmasi.

Although the availability of effective antimicrobial therapy, both otitis media with effusion (OME) and acute bacterial meningitis (ABM) are still important infections for children, leading serious health problems. The most frequently isolated bacteria from cerebrospinal fluid (CSF) of ABM patients are Haemophilus influenzae type b, Neisseria meningitidis and Streptococcus pneumoniae, and middle ear effusion (MEE) samples of OME patients are H. influenzae, S. pneumoniae, Moraxella catarrhalis, respectively. Since they are fastidious bacteria, various problems may arise in the rapid diagnosis in both ABM and OME settings. In this study, the diagnostic value of polymerase chain reaction (PCR) has been searched for the detection of bacterial DNA in CSF and MEE specimens and evaluated in comparison to conventional culture method accepted as the "gold standard". A total of 75 samples (53 CSF, 22 MEE) collected from meningitis and OME suspected children were included in the study. With the conventional culture method, one S. pneumoniae strain was isolated from a CSF sample, and one H. influenzae (non-type b) and two M. catarrhalis strains were isolated from three of MEE samples (total isolation rate: %5.3; 4/75). Standard PCR protocol was applied for the detection of H. influenzae, while multiplex PCR protocol was used for M. catarrhalis and S. pneumoniae, since H. influenzae and S. pneumoniae amplification products were of similar size. PCR revealed genomic DNA sequences of S. pneumoniae from five of the CSF samples, while three H. influenzae, three M. catarrhalis and two S. pneumoniae+M. catarrhalis were detected from MEE samples (total detection rate: %17.3; 13/75). Sensitivity and specificity rates of PCR method were found as 100% and 92.3% for CSF samples, and 100% and 73.7% for MEE samples, respectively, with a total sensitivity of 100%, specificity of 87.3%, positive predictive value of 30.8%, and negative predictive value of 100%. As a result it was concluded that PCR method could be considered as a rapid, reliable and feasible method for the detection of the most common fastidious bacteria that lead to meningitis and OME.

A case of ventricular drainage infection with a rare pathogen in cerebrospinal fluid: vancomycin-resistant Enterococcus faecium.

The purpose of this study was to describe a patient, 7-month-old child with ventriculoperitoneal shunts for hydrocephalus with ventriculitis caused by vancomycin-resistant Enterococcus faecium. Two ventriculoperitoneal shunts were inserted just after birth and on the second month. On the sixth month, both shunts were removed because of dysfunction, and external drainage was inserted. The child developed fever, and lumbar puncture revealed a high leukocyte count and protein concentration after external drainage. Cerebrospinal fluid (CSF) cultures yielded E. faecium, which was resistant to ampicillin, erythromycin, gentamicin, penicillin G, vancomycin, and teicoplanin and was susceptible to chloramphenicol, ciprofloxacin, streptomycin, levofloxacin, and rifampin, as determined by the disk diffusion method. As a result of the antimicrobial susceptibility tests, multidrug antibiotic therapy was changed from vancomycin and ceftazidime to chloramphenicol, rifampin, and meropenem. In addition, a rifampin-clindamycin-impregnated shunt (The Codman Hakim Bactiseal, Raynham, MA) was inserted. The patient became afebrile, and CSF cultures were sterile after 15 days of yielding E. faecium. Implantation of the rifampin-clindamycin-impregnated shunt and timely use of appropriate antibiotics for 10 days according to antimicrobial susceptibility testing seem to be important in the resolution of vancomycin-resistant enterococci infections, especially in countries where linezolid and quinupristin-dalfopristin are not in use yet.

Evaluation of the EVIGENE VRE detection kit for detection of vanA and vanB genes in vancomycin-resistant enterococci.

The aim of this study was to evaluate the performance of the EVIGENE VRE Detection kit and compare it with PCR, considered the gold standard for detection of vancomycin-resistant enterococci (VRE). The correlation between the MIC values of vancomycin and teicoplanin using the epsilon test was also determined. In the EVIGENE VRE Detection kit, DNA probes specific for bacterial target DNA sequences are bound to microwell plates. A hundred and ten VRE (104 Enterococcus faecium and six Enterococcus faecalis) and 45 vancomycin-susceptible E. faecium were tested. All VRE strains were found to be positive for the vanA genotype using the EVIGENE VRE Detection kit. All results obtained with the EVIGENE VRE Detection kit were confirmed by PCR. MIC results for the strains also correlated highly with the PCR and kit results. The EVIGENE VRE Detection kit should be used in preference to other methods for detecting resistance genes in all strains, since it is less time-consuming, does not require the handling of hazardous chemicals and has the same specificity as PCR.

Gastrointestinal microflora studies in late-onset autism.

Some cases of late-onset (regressive) autism may involve abnormal flora because oral vancomycin, which is poorly absorbed, may lead to significant improvement in these children. Fecal flora of children with regressive autism was compared with that of control children, and clostridial counts were higher. The number of clostridial species found in the stools of children with autism was greater than in the stools of control children. Children with autism had 9 species of Clostridium not found in controls, whereas controls yielded only 3 species not found in children with autism. In all, there were 25 different clostridial species found. In gastric and duodenal specimens, the most striking finding was total absence of non-spore-forming anaerobes and microaerophilic bacteria from control children and significant numbers of such bacteria from children with autism. These studies demonstrate significant alterations in the upper and lower intestinal flora of children with late-onset autism and may provide insights into the nature of this disorder.

Linezolid and quinupristin/dalfopristin resistance in vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus prior to clinical use in Turkey.

The aim of this study was to determine the in vitro antimicrobial activity of recently licensed quinupristin/dalfopristin and linezolid which have not yet been in clinical use in Turkey against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains isolated from various clinical specimens by using the Etest. The results showed that all MRSA strains were fully susceptible to both the new compounds. All strains were inhibited by 1 mg/l quinupristin/dalfopristin (mode MIC 0.38 mg/l) and by 3 mg/l linezolid (mode MIC 1.5 mg/l). Four strains of Enterococcus faecium showed an increase of resistance of 2-3 mg/l to quinupristin/dalfopristin (susceptible mode MIC 0.38 mg/l). With linezolid, all strains except two fell within the range 0.75-2.0 mg/l.

[Macrolide antibiotic resistance rates and phenotypes of group A beta hemolytic streptococci isolated between the years 1999-2000 and 2001-2002]. / 1999-2000 ve 2001-2002 yillarina ait grup A beta hemolitik streptokok izolatlarinin makrolid antibiyotiklere direnç oranlari ve fenotipleri.

Macrolide resistance in group A beta hemolytic streptococci (GABHS) have been reported with increasing frequency from various geographic regions in the world, and for the respective treatment alternatives and epidemiologic studies, macrolide resistance rates and phenotypes have been determined. In this study erythromycin, clarithromycin and azithromycin were tested with disc diffusion method against 560 GABHS, isolated from the throat samples collected between 1999-2002. NCCLS guidelines were followed for the susceptibility tests and MIC values were obtained by E-Test in resistant isolates. For determining the resistance phenotype, erythromycin and clindamycin discs were used. Only one isolate (0.27%) was found intermediately resistant to erythromycin, and clarithromycin, and resistant to azithromycin between May 1999-January 2000, whereas in the period between January 2001-June 2002, one isolate (%0.5) was found susceptible to erythromycin and clarithromycin, but intermediately resistant to azithromycin. In each period three isolates (0.83% and 1.5%, respectively) were found to be resistant to all the tested macrolides. There was no statistically significant difference between the resistance rates in these periods. Three of the resistant isolates had inducible type, and the other five isolates had M phenotype macrolide resistance. Testing for macrolide susceptibilities and screening the resistance phenotypes have crucial importance in case of GABHS infections, since these can be taken into consideration for epidemiological issues as well as a guide for empirical treatment protocols in any geographical setting, as well as in our country.

[Investigation of the in-vitro effectiveness of ertapenem against Pseudomonas aeruginosa strains isolated from intensive care unit patients]. / Yogun bakim ünitelerinde yatan hastalardan izole edilen Pseudomonas aeruginosa suslarina karsi ertapenemin in-vitro etkinliginin arastirilmasi.

Pseudomonas aeruginosa is one of the important cause of infections in intensive care unit (ICU) patients. The aim of this study was to investigate the effectiveness of ertapenem prior to its use in Turkey, against multiple-resistant P. aeruginosa strains isolated from ICUs. Susceptibility tests were performed by using Kirby-Bauer disk diffusion method and MicroScan MERCH MIC 8 panel (MicroScan 96, Dade Behring, USA). While the resistance rates of ertapenem, imipenem and meropenem were 59.2%, 50% and 48.1% by disk diffusion method, they were 57.4%, 46.2% and 42.5% by MicroScan, respectively. Ertapenem was found less effective against multiple-resistant P. aeruginosa isolates by both of the methods when compared with imipenem and meropenem. Piperacillin/tazobactam was detected as the most effective agent against these isolates by both of the methods. As a result, although carbapenems are frequently used for infections caused by P. aeruginosa, ertapenem, which is a new carbapenem, is not effective as much as the others. In case of confirmation of our results by larger scale studies, the empiric treatment of ICU infections caused by P. aeruginosa with ertapenem, should be carefully evaluated.

Bacterial reduction by extensive versus conservative root canal instrumentation in vitro.

OBJECTIVE: This study aimed to test the hypothesis that aggressive dentin removal through greater-tapered instrumentation reduces the intracanal bacteria more effectively than conservative dimension instrumentation. MATERIAL AND METHODS: Twenty extracted human lower premolar teeth were used. After extirpation of the pulps, the teeth were autoclaved and immersed in a broth inoculated with Enterococcus faecalis and incubated for 7 days to allow infection of the dentinal tubules. The teeth were divided into 2 experimental groups, each comprising 10 teeth. The teeth were instrumented either with ProTaper or with Hero Shaper nickel-titanium rotary instrumentation techniques. It was calculated that ProTaper theoretically has the potential to remove at least twice the dentin volume compared with Hero Shaper. The apical preparation was standardized to file size 30. Saline solution was used for irrigation. Bacteriological samples were taken before and after instrumentation and plated onto tryptic soy agar, and the reduction in numbers was calculated. RESULTS: Both instrumentation techniques significantly reduced the number of bacteria in the root canal (p<0.05). Reduction in absolute bacterial numbers was up to 98%. There was no statistically significant difference between the two techniques. CONCLUSIONS: Preparation with an instrumentation technique removing substantial amounts of dentin did not reduce the intracanal bacteria more effectively than a more conservative instrumentation technique.

In vitro antimicrobial activity of propolis samples from different geographical origins against certain oral pathogens.

Propolis is an agent having antimicrobial properties, however, its composition can vary depending on the area where it is collected. In the present study, the antimicrobial activity of five propolis samples, collected from four different regions in Turkey and from Brazil, against nine anaerobic strains was evaluated. Ethanol extracts of propolis (EEP) were prepared from propolis samples and we determined minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of EEP on the growth of test microorganisms by using agar dilution method. All strains were susceptible and MIC values ranged from 4 to 512 microg/ml for propolis activity. Propolis from Kazan-Ankara showed most effective MIC values to the studied microorganisms. MBC values of Kazan-Ankara EEP samples were ranged from 8 to 512 microg/ml. Death was observed within 4 h of incubation for Peptostreptococcus anaerobius and micros and Lactobacillus acidophilus and Actinomyces naeslundii, while 8 h for Prevotella oralis and Prevotella melaninogenica and Porphyromonas gingivalis, 12 h for Fusobacterium nucleatum, 16 h for Veillonella parvula. It was shown that propolis samples were more effective against Gram positive anaerobic bacteria than Gram negative ones. The organic chemical compositions of EEPs were determined by high-resolution gas chromatography coupled to mass spectrometry (GC-MS). The main compounds of EEPs were flavonoids such as pinobanksin, quercetin, naringenin, galangine, chrysin and aromatic acids such as cafeic acid. Because of increased antimicrobial resistance, propolis may be kept in mind in the treatment of oral cavity diseases.