Prevalence, antibiotic resistance and virulence of Enterococcus spp. isolated from traditional cheese types

BACKGROUND: Enterococci are naturally found in the gastrointestinal (GI) tract of animals and humans, as well as animal-derived foods and vegetables. We here aimed to determine the prevalence, antibiotic resistance, and virulence determinants of E. faecium and E. faecalis in traditional cheese in the North-west of Iran.MATERIALS AND METHODS: Fifty specimens of popular traditional cheese from dairy stores of Urmia and Tabriz, Iran, were collected. Identification of the genus and species of enterococci was done using molecular and phenotypic techniques.RESULTS: Forty-eight (96 %) of 50 traditional cheese samples were harboring Enterococcus spp, including Enterococcus faecalis (n= 40; 83.33 %) and E. faecium (n= 8; 16.67 %). The prevalence of enterococci ranged from 1.1×105 to 9.7×104 CFU/g, and 1.1×103 to 9.8×103 CFU/g in Urmia and Tabriz samples, respectively. Rifampicin resistance (n= 38; 79.2 %) was the most common pattern observed in the susceptibility test, which was followed by quinupristin/dalfopristin (n= 33; 68.75 %). Among E. faecalis isolates, cpd (100 %), ace (92.5 %) and gelE (87.5 %), and among E. faecium isolates, gelE (100 %) and asa1 (75 %) were found to have the most common virulence genes.CONCLUSION: E. faecalis was the predominant species, displaying more virulence determinants. It also had high antibiotic resistance, as compared to E. faecium. The enterococci identified here commonly expressed virulence and antibiotic resistance determinants. So, it is required to improve the maintenance and production quality of traditional cheese to avoid enterococci contamination

Investigations of the neural basis of source memory strength

When an attempt is made to recognize something, we can remember different aspects of the original experience. You may have a memory of the individual items you have encountered. We may also have memories of where those items came from, the source of those memories. Source memory includes elements regarding the perceptual or conceptual context of an item, such as the person who said or wrote it, whether the item was seen inside or outside, or your internal state when the memory was encoded. Some cognitive models of source memory suggest that it is a probabilistic threshold process (Yonelinas, 2002), while others predict that it varies along a continuum of memory strength (Mickes, Wais, & Wixted, 2009; Slotnick, 2010). These models have been largely debated as part the discussion of dual-process theories of memory, leaving open cognitive neuroscience questions about brain structures involved in variations in the strength of source memory (Wixted, 2009; but see Vilberg & Rugg, 2009; Yu, Johnson, & Rugg, 2012). The dominant viewpoint in cognitive Neuroscience was that source memory did not vary in strength, leading to a lack of research into the topic. However there is evidence that this may have lead to a misrepresentation of the brain’s role in the strength of source memory (Wais, 2008) . This dissertation presents a series of experiments that explore the links between brain structures and variations in the strength of source memory. Chapter 2 uses fMRI to examine the role of the hippocampus in source memory strength. Previous dual-process oriented research suggests that a process of recollection would be necessary for source memory, but a process of familiarity would be sufficient for memory of an individual item. Brain imaging studies support the idea that that recollection is mediated by the hippocampus and familiarity by surrounding cortex. However, some researchers dispute this distinction, claiming that the hippocampus responds to the overall strength of memory, not source memory specifically (Kirwan, Wixted, & Squire, 2008; Shrager, Kirwan, & Squire, 2008; Wais, 2008). The experiment in Chapter 2 measured memory type (item and source) and the strength of both to examine whether the hippocampus responds differentially to each type of memory strength. The finding was that hippocampal activity increased with the strength of source memory, but not with item memory strength. This suggests that while the hippocampus does preferentially respond to source retrieval, it does so in a graded fashion with strength. The parietal lobes also showed a differential pattern of activity to item and source strength with different subregions involved in processing item and source memory. Dorsal regions are often associated with processing item memory, and ventral regions with source memory. This may reflect differences in bottom-up versus top-down driven attentional mechanisms (Cabeza, Ciaramelli, Olson, & Moscovitch, 2008) or difference in the accumulation of different types of mnemonic information (Vilberg & Rugg, 2008). The left frontal lobe was increasingly active for item memory strength, suggesting it plays a role of increased effortful retrieval (Henson, Shallice, & Dolan, 1999) or monitoring of source information (Mitchell & Johnson, 2009) to high confidence items. This first study left open questions about the circumstances under which other brain regions contribute to source memory strength. Chapter 3 used fMRI to examine the domain specificity of source memory strength, such as which brain regions are more active for source memory in general and which regions differed in their contribution to source strength depending on stimulus content. The retrieval of information leads to the reactivation of the brain regions that were engaged during encoding of the memory (Danker & Anderson, 2010; Rissman & Wagner, 2012; Walker, Low, Cohen, Fabiani, & Gratton, 2014), this reactivation could also contribute to source memory strength. My paradigm used pairings of words with faces or scenes during encoding, and tested memory for the associated picture with words alone. I found that the hippocampus increased its activity in a domain-general way, increasing with source memory strength to words regardless of associated stimulus type (face or place). The parahippocampal place area shows preferential activity when viewing scenes (Epstein & Kanwisher, 1998). This study found the left parahippocampal cortex to be increasingly active with confidence that a word had been previously paired with a place. Bilateral amygdala is active during the processing of face stimuli (Ishai, 2008) This study found the amygdala was increasingly active with confidence that a word was previously paired with a face. These two regions show domain-specificity in their contribution to source memory strength since they only activate to words paired with certain classes of stimuli, faces or places. Thus, while perceptual processing regions of the brain specific to faces and places showed domain-specificity, the hippocampus was involved in successful source retrieval in a domain general manner, suggesting it supports memory for all types of sources. An open question was whether the activations observed in the previous experiment represented the remembering of general categorical information diagnostic of the source question or the remembering of the specific associated stimuli. Chapter 4 examined the difference in the neural response when remembering general categorical source information or memory of specific associative information using Event Related Potentials (ERPs). During encoding, participants were shown words paired with scenes that were either natural or man-made. When shown the words again during the memory test, the participants were asked a source question, whether the associated scene was natural or manmade. Immediately following the categorical source question, they were asked to identify the specific paired scene from an array consisting of the original stimulus and two within-category lures. Thus I was able to examine ERPs reflecting source category memory retrieval separately from remembering specific associated items. Previous ERP studies have found correlations between recollection of source memory and the “LPC” component (for review see Rugg & Curran, 2007). The amplitude of the LPC has also been shown to track confidence in source memory (Woroch & Gonsalves, 2010). ERP amplitudes in the LPC time window were related to confidence in the category source judgment, but not to success at recognizing the specific associated image. Immediately following the scene category decision, subjects were given a forced choice test probing their memory for the specific associated scene. Success in that decision was related to increased amplitude late in the time window. I conclude that remembering specific information involves increases source-monitoring demands indexed by the frontal ERPs. Across all three studies, multiple brain regions and processes were involved in source memory strength, suggesting source memory is a continuous process, not simply an all or none threshold process. The fMRI data suggest the hippocampus and ventral parietal cortex track source memory in a domain-general fashion, suggesting a global binding mechanism (hippocampus), and attention to memory or memory representation (ventral parietal) processes. Domain-specific perceptual processing regions showed reactivation during retrieval that also tracked source strength, suggesting source memory strength is also affected by the richness of the reinstatement of the memory representation. The ERP results suggest that while these domain general processes, such as source retrieval indexed by the LPC, do support general source memory strength, additional executive processes, such as post-retrieval monitoring, may be necessary to support memory for specific associations at retrieval

Frequency of bap and cpaA virulence genes in drug resistant clinical isolates of Acinetobacter baumannii and their role in biofilm formation

Objective(s): Acinetobacter baumannii has a high propensity to form biofilm and frequently causes medical device-related infections with multiple-drug-resistance in hospitals. The aim of this work is to study antimicrobial resistance and the role of bap and cpaA genes in biofilm formation by A. baumannii to understand how this pathogen persists in the hospital environment. Materials and Methods: Theantibiotic resistance profile and in vitro biofilm-forming ability of one hundred clinical isolates of A. baumannii was evaluated by disc diffusion and crystal-violet staining methods, respectively. Isolates were tested for the presence of bap and cpaA genes. Results: The isolates were highly resistant to cefepime, third-generation cephalosporins, ciprofloxacin, cotrimoxazole, aminoglycosides and carbapenems. Moreover, four isolates were resistant to colistin. Quantification of biofilm showed that 43% of the isolates were strong biofilm-producer. Furthermore, 32% of the isolates exhibited moderate biofilm-formation and showed initial binding activity. Frequency of bap and cpaA were determined 92% and 36%, respectively. Conclusion: There was strong association between the presence of bap gene and biofilm formation by A. baumannii isolates (P=0.003). In addition, multidrug resistant isolates produced stronger biofilm than other isolates (P=0.0001). These results indicate importance of biofilm in resistance of isolates and effect of presence of bap gene in biofilm formation by A. baumannii strains

Detection of integrons among multi-drug resistant (MDR) Escherichia coli strains isolated from clinical specimens in northern west of Iran

Transference of resistance determinants by integrons is one of the important factors that can contribute to the increase in multi-resistant bacteria. We determined the prevalence and class of integrons among multi-drug resistant (MDR) Escherichia coli strains isolated from clinical specimens in Tabriz teaching hospitals. Firstly, susceptibility of 140 isolates to 13 antibiotics was determined using the disc diffusion method. Then, prevalence and class of integrons was detected in MDR strains by PCR-RFLP. One hundred five (75%) of total 140 isolates were uropathogenic Escherichia coli (UPEC). Other pathotypes included were: diarrheagenic Escherichia coli (13; 9.3%), sepsis-associated E. coli (5; 3.6%) and newborn meningitis-associated E. coli (2; 1.4%). Antibiotic resistance patterns were as follows: amoxicillin 99.3%, gentamicin 33.6%, tetracycline 72.8%, ceftazidime 46.4%, co-trimoxazole 75%, imipenem 1.4%, ciprofloxacin 47.6%, norfloxacin 50.7%, cephalothin 77.8%, amikacin 12.1%, nitrofurantoin 12.9%, chloramphenicol 20.7% and nalidixic acid 60.7%. One hundred eighteen (84.2%) of tested isolates were multi-drug resistant. Prevalence of integrons was confirmed in 27.1% of MDR isolates. intI1 and intI2 were detected respectively in 22.05% and 5.08% of MDR strains. No intI3 was detected. Resistance to gentamicin, amikacin and chloramphenicol was significantly associated with the presence of integrons. These results showed high resistance of E. coli to routine antibiotics, however, in consideration of low prevalence of integrons among these strains, we can conclude that antibiotic resistance genes in these strains presumably carried on elements other than integrons

The Study of Nosocomial Infections in Neonatal Intensive Care Unit, A prospective study in Northwest Iran

Background: Nosocomial infections are an important cause of mortality in neonatal intensive care units (NICUs). Therefore, in this study, the incidence and prevalence of nosocomial infections were determined in NICUs of the three largest neonatal centers in northwest Iran, and the causative bacteria were identified in order to provide potential solutions to control the infections in these hospitals. Materials and Methods: This is a descriptive-prospective study in which the cases of nosocomial infections were examined in the three largest hospitals in Tabriz in northwest Iran during 1 year (from June 2012 until May 2013) based on clinical findings, medical and nursing reports of patients, and laboratory results. Results: Of the 3129 patients hospitalized in NICUs of the three hospitals, 208 patients were diagnosed with nosocomial infections. The incidence rate of nosocomial infections was 11.34%.per 100 patient days with 52.4% bacteremia, 32.69% pneumonia, 5.77% urinary tract infections, 5.29% wound infections, and 3.85% necrotizing enterocolitis. There was a statistically significant relationship between invasive procedures (such as umbilical catheters, central venous catheters, surgery, and TPN) and sepsis (P = 0.001). The relationships between urinary tract infection and urinary catheter (P = 0.000), and aggressive procedures (such as suctioning and intubation) and pneumonia (P = 0.001) were also statistically significant. Conclusion: Incidence of nosocomial infections in premature and low birth weight newborns is considered as a health threat. The findings of this research reiterate the importance of giving further attention to prevention and control of nosocomial infections in the NICU

Effect of QRDR Mutations on Ciprofloxacin Resistance in Clinical Isolates of Pseudomonas aeruginosa

Background & objectives: Fluoroquinolones have important role in treatment of P. aeruginosa infections. The main mechanism of fluoroquinolones resistance in P. aeruginosa is mutations in the quinolone-resistance-determining region (QRDR) of gyrA and parC genes. The aim of this study was to investigate the role of these mutations in ciprofloxacin resistance in different clinical isolates of P. aeruginosa. Methods: A total of 75 clinical P. aeruginosa isolates were collected from different university-affiliated hospitals in Tabriz. Minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated by Etest assay. DNA sequences of the QRDR of gyrA and parC were determined by dideoxy chain termination method. Results: From 75 isolates, 77.33% were resistant to ciprofloxacin. No amino acid changes were detected in gyrA or parC genes of the ciprofloxacin susceptible isolates. Thr-83&rarr;Ile substitution in gyrA was observed in all ciprofloxacin resistant isolates. About 90% of them had Ser-87&rarr;Leu substitution in parC. Geometric mean MICs of ciprofloxacin were different for various clinical isolates of P. aeruginosa which had the same situation in type and location of gyrA and parC mutations. Moreover, the geometric mean MIC in isolates from urine was significantly (p<0.05) higher than isolates from tracheal aspirates. Conclusion: Mutations in gyrA and parC genes are the major mechanisms for ciprofloxacin resistance in clinical isolates of P. aeruginosa. Moreover, the role of different effective factors in fluoroquinolone resistance can be different in various clinical isolates of P. aeruginosa

Comparison of the antibiotic resistance patterns among Shigella species isolated from pediatric hospital between 1995-1999 and 2009-2013 in North-West of Iran

Introduction: This study was conducted to determine the frequency and pattern of antimicrobial susceptibility of Shigella spp. isolated from pediatric hospital in two different time periods between March 1995 to March 1999 and March 2009 to March 2013 in North-West of Iran. Methods: The stool specimens were collected and examined for shigellosis by biochemical tests, and antibiogram was conducted according to Clinical and Laboratory Standards Institute protocol. One hundred and thirty-nine Shigella spp. isolated from year 1995 to 1999 and 38 Shigella spp. isolates collected from year 2009 to 2013 and examined for serotyping and antibiotic resistance pattern. Results: According to serotyping results Shigella flexneri isolated in 98.6% of isolates in the first time period, followed by Shigella boydii and Shigella sonnei (0.7%) but in the second time period just 47.3% were S. flexneri and 39.5% were S. sonnei, 7.9% were S. boydii and 5.3% of isolates were Shigella dysenteriae. Results indicated significantly increase in resistance to ceftizoxime, chloramphenicol, and amikacin (P = 0.004, 0.010, and 0.004 respectively), also, in Shigella isolates isolated in the second time period showed an increase in multidrug resistant (MDR) isolate and frequency of MDR isolates increased to 95.0% in the second time period. Conclusion: We are facing with the increase in resistance to antibiotics in Shigella spp. especially MDR isolates. These results showed changing pattern of resistance in Shigella isolates and needs for planning and design antibiotics stewardships for controlling Shigellosis, especially in pediatric hospitals