سال:1396 | دوره: | شماره: |تعداد مقالات:9

Background: Enterococcus spp., a part of the normal flora of the human intestine, possess several virulence factors that can develop biofilms to endure harsh environments. Their ability to cause nosocomial infections makes them as critical opportunistic pathogens in hospital settings. Objectives: The current study aimed at determining the occurrence of 6 genes coding virulence factors and their ability to develop biofilms, and conducting phenotypical assessments of haemolysin and gelatinase in clinical enterococci isolated from theWest of Iran. Methods: A total of 126 isolates were screened for harbouring the following genes: aggregation substance (asa1), cytolysin (cylABM), enterococcal surface protein (esp), and gelatinase (gelE). Isolates were tested for haemolysin and gelatinase expression phenotypically and for biofilm production quantitatively, using the microtiter method. Results: Of the 126 tested isolates, 95 (73%) were Enterococcus faecalis and 28 (21%) were E. faecium. The total frequency of virulence gene was cylA 92 (73%), cylB 85 (67%), cylM 57 (45%), asa1 26 (21%), gelE 64 (51%), and esp 66 (53%); while 98 (75%) of the isolates were able to form biofilm. A total of 74 (58%) and 46 (35%) isolates could secret haemolysin and gelatinase. Conclusions: There was a significant difference between the frequency of virulence gene in E. faecalis and E. faecium. Enterococcus faecium isolates lacked the gelE and asa1 genes and the frequency of cylABM genes were lower than that of E. faecalis isolates. Enterococcus faecalis isolates were relatively rich in virulence factors; no association was observed between biofilm formation and the presence of specific virulence genes.

Background: Temperature sensitive plasmid pBBR1MCS2-Ts, mutated from pBBR1MCS and derived from pBBR1, is a broad host range plasmid and it is especially useful for gene targeting and integration in various hosts. The plasmid copy number (PCN) of temperature sensitive plasmid in host mainly depends on the stability of plasmid. Objectives: The present study aimed at investigating the PCN of pBBR1MCS2-Ts and pBBR1MCS2 at permissive (30° C) or nonpermissive (42° C) temperatures. Methods: The rep gene in the plasmid and the dxs gene in the Escherichia coli genome were used as target and reference gene. A standard plasmid pLB1k-dxs-rep was constructed for real time PCR calibration. The PCNs were calculated by absolute and relative quantitation. Total DNA of E. coli T1 harboring plasmid pBBR1MCS2 or pBBR1MCS2-Ts were extracted and real time qPCR were performed in triplicate, with 2 independent biological replicates. Results: The primer setsQrep andQdxs produced specific products and could be used to detect the target plasmid and chromosomal DNA, respectively. The PCN determined by the absolute and relative quantitation PCR were similar and reproducible. The PCN of pBBR1MCS2 in E. coli was about 19 when cultured at 30° C and about 10 when cultured at 42° C, and the PCN of pBBR1MCS2-Ts was about 6 when cultured at 30° C and nearly zero when cultured at 42° C. Compared with pBBR1MCS2, the temperature shift from 30° C to 42° C caused a significant decrease in the PCN of temperature sensitive plasmid pBBR1MCS2-Ts. Conclusions: ThePCNof temperature sensitive plasmid was very low at 42° C and temperature sensitivity of the plasmid was mainly caused by the mutation of rep ORF, which subsequently affected the plasmid replication and stability.

Background: Acinetobacter baumannii is known as a potential pathogen in hospitals and is responsible for the dramatic increase in carbapenem resistance in Iran in the recent years. Objectives: The current study aimed at determining the genetic association of the isolates by the pulsed-field gel electrophoresis (PFGE) technique, identify international clones, evaluate biofilm formation ability and its relationship with antibiotic resistance. Methods: In the current study, a total of 48 A. baumannii isolates were collected from 2 hospitals in Tehran, Iran, from 2010 to 2012. Isolates were subjected to antimicrobial susceptibility testing, determination of carbapenemase encoding genes, biofilm formation, and genetic relationships analysis. Results: The obtained results demonstrated that the rate of resistance to carbapenem, meropenem, imipenem, and doripenem was 76%. The carbapenemase-encoding gene blaOXA-23-like was found in 32 isolates, while blaOXA-40-like (blaOXA-24-like), blaOXA-58-like, blaVIM-type and blaIMP-type were found in 11, 1, 19. and 5 isolates, respectively. When the lineage of the isolates was evaluated by the multiplex polymerase chain reaction (PCR), it was found that 28 isolates belonged to group 1 and 8 isolates to group 2. None of the isolates belonged to group 3. Twelve isolates could not be typed by this method. The study findings interestingly demonstrated that 13 isolates showed no biofilm formation. Data of biofilm formation also demonstrated that 28, 4, and 3 remaining isolates had weak, moderate, and strong biofilm formation, respectively. The pulsed field gel electrophoresis result revealed 11 unique clones. Conclusions: International clone 1 was the most commonly identified clone in the current study. This clone was mostly associated with blaOXA-23-like gene; therefore, 64% of the isolates in this clone possessed blaOXA-23-like gene.

Background: Acinetobacter baumannii has increasingly become one of the most common pathogens causing ventilator-associated pneumonia (VAP). Objectives: In the present study, we aimed to assess the presence of extended-spectrum beta-lactamase (ESBL) and integron genes in A. baumannii isolates from VAP patients in the intensive care units (ICUs) of 18 hospitals in North of Iran. Methods: All patients, who were ventilated for at least 48 hours, were assessed daily for VAP. The minimum inhibitory concentrations were determined according to the standard protocol by the clinical and laboratory standards institute (CLSI). ESBL-producing A. baumannii was detected, using the double-disk synergy test. ESBL-positive A. baumannii isolates were screened for CTX, VEB, GES, SHV, int1, and int2 genes, using polymerase chain reaction (PCR) amplification. Results: In total, 29 out of 205 patients with nosocomial infections, admitted to ICUs during 2014-2015, showed VAP caused by ESBL-producing A. baumannii. A total of 19 (65. 51%) strains were extensively drug resistant (XDR). As the findings revealed, the rates of imipenem and colistin resistance were 55. 2% and 34. 5%, respectively. The prevalence of CTX, VEB, and SHV genes in ESBL-producing A. baumannii was 34. 5%, 17. 2%, and 96. 6%, respectively. Also, 79. 3% of the isolates had class 1 integrons, while 10. 3% contained class 2 integrons. Conclusions: Presence of integrons in A. baumannii has been considerably associated with ESBL genes. The high rate of SHV and int1 genes highlights the necessity of avoiding aminoglycosides for empirical therapy. Although colistin was the most sensitive antibiotic inXDRstrains in our region, due to the presence of patients with A. baumannii in ICUs, colistin resistance screening should be performed before empirical therapy for VAP, even for those without prior exposure to this antibiotic.

Background: Multidrug resistant (MDR) Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia have a leading role in nosocomial infections, including lower respiratory tract (LRT) infections. When polymicrobial infection by these three bacteria occurs, colistin against MDR P. aeruginosa and A. baumannii and trimethoprim/sulfamethoxazole (SXT) against S. maltophilia can be an optional antimicrobial strategy. Objectives: The aim of this study was to investigate the potential synergic effect of colistin-plus-SXT against thoseMDRP. aeruginosa, A. baumannii and S. maltophilia isolates that were isolated at the same time, from the same LRT sample of patients. Methods: Sixty connected isolates from 20 different patients were collected in a two-year study period. The checkerboard method and time-kill assays were used for synergy testing. Results: All P. aeruginosa and A. baumannii strains were susceptible to colistin, whereas all S. maltophilia isolates were resistant to it. Fifteen percent of MDR A. baumannii strains and all S. maltophilia isolates were susceptible to SXT. By the checkerboard method, colistin-plus-SXT showed synergy in 50%, 35% and 45% of S. maltophilia, MDRP. aeruginosa andMDRA. baumannii strains, respectively. Antagonistic effect was not found. A time-kill assay was performed on strains which showed synergy by the checkerboard method: 70%, 57% and 56% of S. maltophilia, P. aeruginosa and A. baumannii strains showed the same results. Synergic activity of the combination was already detected after 6 h incubation in 86% of S. maltophilia isolates and 50% of P. aeruginosa strains. Regrowth of A. baumannii after 24 hour in the presence of colistin was prevented by the combination. The results gained by CB and TKA methods correlated in 61% of cases, but the FIC values did not correlate with the rate of log10 decrease in TKA. Colistin-plus-SXT combination had synergic effect on 35% of S. maltophilia, 20% of P. aeruginosa and 25% A. baumannii strains by both methods. Conclusions: According to our in vitro results, colistin-plus-SXT combined therapy can be used efficiently in clinical practice as no antagonistic effect was detected. In certain cases colistin-plus-SXT has a synergic effect against MDR P. aeruginosa, A. baumannii and S. maltophilia.

drugs resistance in some Candida species and their side effects, conducting research to find new resources, especially medicinal plants, are of prime importance. Objectives: The present study aimed at evaluating anti-Candida activities and antioxidant function of hydroalcohlic extract of seeds of Rumex obtusifolius and analyzing GC mass for the determined material, which included especial formulated extract. Methods: The Rumex obtusifolius seeds were extracted using Ethyl acetate: methanol: distilled water (6: 3: 1) by Soxhelet system. The antifungal activity as well as total free phenolics and flavonoids content were examined. The extract was carried out against 40 isolated Candida species such as Candida albicans and C. glabrata through well diffusion method. In addition, hydroalcoholic extraction of R. obtusifolius was evaluated for its antioxidant capacities using 1-diphenyl-2-picrylhydrazyl radical scavenging. The components of the extract were analyzed via Gas chromatography-Mass spectrometry (GC-Mass) instrument. Results: The minimum inhibitory concentration (MIC) values were 100-150  g/ L for C. albicans 150  g/ L for C. glabrata. The hydroalcoholic extract can strongly scavenge DPPH radical, and its antioxidant capacities may be correlated with the total free phenolics and total flavonoids. This study revealed the highest antioxidant capacity in the seeds of R. obtusifolius compared to the control groups. Conclusions: The extract contained a highamountof phenolic compounds, and its antioxidant activity was significant. The seed of R. obtusifolius has strong anticandidial and antioxidant activities, which may be due to the presence of high levels of phenolic compounds, particularly pyrogallol.

Background: Cryptosporidiosis is a major public health problem for neonatal livestock worldwide. Cryptosporidium parvum infects intestinal epithelial cells via contaminated food or drinking water and leads to cryptosporidiosis. Most of the animal model studies on infectivity of C. parvumare conducted on the neonatal mice. Objectives: The current study aimed at evaluating the infectivity of C. parvum in neonatal rat as an animal model. Methods: A dose of 100, 000 to 120, 000 C. parvum oocysts (Iowa strain, BTF Company, Sydney, Australia) was orally inoculated in a group of 30 neonatal Wistar rats aged 2 days old. Eight days postinfection, jejunum, ileum, cecum, colon, and rectum were removed and contents were homogenized and purified using sucrose gradient method. Results: Our results indicated that 6 to 12 million C. parvum was found per rat Conclusions: Analysis of the study results revealed that the neonatal rat could be used as an alternative animal model to investigate C. parvum.

Background: Ulcerative colitis is a kind of inflammatory bowel disease that is considered as immunological response to commensal bacteria colonizing gut lumen. Adherent-invasive Escherichia coli strains are pathogens responsible for ulcerative colitis disease. These bacteria have special virulence factors, including type 1 fimbriae, which could be involved in inflammatory bowel disease. Objectives: The present study was conducted to determine the prevalence of adherent-invasive E. coli with fimH gene isolated from Iranian patients with ulcerative colitis. Methods: Sixty intestinal biopsy samples of 30 patients with ulcerative colitis and 30 individuals without inflammatory bowel disease were examined. Biopsies from rectum, descending, ascending, terminal ileum, and colon were taken during colonoscopy. Results: All biopsy samples were cultured for isolation of E. coli strains. Using polymerase chain reaction assay, the invasive plasmid antigenHand invasion-association locus genes were detected from both isolated bacteria and tissue specimens to confirm the presence of adherent-invasive E. coli. The frequency of adherent-invasive E. coli with type 1 fimbriae was much higher in patients with ulcerative colitis than control subjects. Among isolated bacteria, type 1 fimbriae of adherent-invasive E. coli were detected in 53. 3% and 13. 3% of ulcerative colitis patients and control subjects, respectively. In addition, from 60 biopsy samples, type 1 fimbriae were detected in 56. 7% of ulcerative colitis patients but in 10% of healthy subjects. Conclusions: Subjects without inflammatory bowel disease had a high rate of E. coli strains than patients with ulcerative colitis via cultivation detection. We found a high rate of type 1 fimbriae of adherent-invasive E. coli in ulcerative colitis patients by polymerase chain reaction assay. It appears that the presence of adherent-invasive E. coli with type 1 fimbriae in the gastrointestinal tract of patients with ulcerative colitis is more likely than previously supposed.

Introduction: Bordetella bronchiseptica is an aerobic, Gram-negative pleomorphic coccobacillus. It can infect variousmammalsincluding cats, dogs, and pigs. Bordetella bronchiseptica rarely infect humans. Infants, immunosuppressed and HIV infected persons, and patients with comorbidities constitute the risk group for B. bronchiseptica infections. Bordetella bronchisepticamaylead to disseminated infection, cavitary pneumonia, and rarely fatal tracheobronchitis and sepsis. Case Presentation: A patient who was in follow-up due to acquired immunodeficiency syndrome (AIDS) was admitted to our hospital with persistent dry cough and fever for 4 weeks. The clinical history revealed the presence of classical anti-retroviral resistant HIV infection, and the development of blindness in the right eye because of retinitis. The case was considered as febrile neutropenia; the meropenem therapy was started empirically. Even though we were able to get fever response with empirical therapy, cough remained persistent. Throat culture was inoculated into 5% sheep blood agar and incubated at 37° C. Gram-negative coccobacillus was detected in the examination. Then, the colonies were loaded to MALDI-TOF-VITEK MS and the disease factor was determined as B. bronchiseptica. We stopped meropenem therapy on 7th day and administered clarithromycin 2 500mg orally for 14 days. Conclusions: In AIDS patients with chronic cough, B. bronchiseptica should be considered as a pathogen causing opportunistic infection. In this manuscript, we report a case of tracheobronchitis caused by B. bronchiseptica in an AIDS patient.