Genomic diversity of ß-lactamase producing Pseudomonas aeruginosa in Iran; the impact of global high-risk clones.

BACKGROUND: Hospital-acquired infections caused by multidrug-resistant Pseudomonas aeruginosa incline hospital stay and costs of treatment that resulted in an increased mortality rate. The frequency of P. aeruginosa high-risk clones producing carbapenemases was investigated in our clinical samples. METHODS: In this cross-sectional study, 155 non-repetitive P. aeruginosa isolates were included from different medical centers of Iran. Antibiotic susceptibility testing was determined, and the presence of ß-lactamases were sought by phenotypic and genotypic methods. The clonal relationship of all isolates was investigated, and multi-locus sequence typing (MLST) was used for finding the sequence types of carbapenemase-producers. RESULTS: The agent with highest percent susceptibility rate was recorded for colistin (94.9%). MOX and FOX were found both as low as 1.95% (3/155). The most frequent narrow spectrum ß-lactamase was SHV with 7.7% (12/155) followed by PER, OXA-1, and TEM with the frequency of 7.1% (11/155), 3.2% (5/155), and 1.3% (2/155), respectively. Carbapenemases were detected in 28 isolates (18%). The most frequent carbapenemase was IMP with 9% (14/155) followed by NDM, 8.4% (13/155). OXA-48 and VIM were also detected both per one isolate (0.65%). MLST of carbapenem resistant P. aeruginosa isolates revealed that ST244, ST664, ST235, and ST357 were spread in subjected clinical settings. REP-PCR uncovered high genomic diversity in our clinical setting. CONCLUSION: Clonal proliferation of ST235 strain plays a key role in the propagation of MDR pattern in P. aeruginosa. Our data showed that high-risk clones has distributed in Iran, and programs are required to limit spreading of these clones.

Molecular Typing of Multidrug-Resistant Acinetobacter baumannii Isolates from Clinical Specimens by ERIC-PCR and MLVA.

Acinetobacter baumannii, a Gram-negative and oxidase-negative bacterium, is a major cause of nosocomial infections, leading to high mortality rates in hospitalized patients. The use of 2 prominent molecular typing methods (i.e., enterobacterial repetitive intergenic consensus-polymerase chain reaction [ERIC-PCR] and multiple-locus variable-number tandem repeat [VNTR] analysis [MLVA]) for genotyping A. baumannii isolates has proven to be an effective approach in assessing the clonal relation of these isolates and managing their outbreaks. A total of 100 A. baumannii isolates were collected from immunocompromised patients hospitalized in the intensive care unit (ICU) of a hospital in Zanjan City, Iran. Their antibiotic resistance ability (especially aminoglycoside resistance) was studied by disc diffusion tests. The genetic typing of A. baumannii was studied using ERIC-PCR and MLVA methods. All isolates were resistant to 3 or more antibiotics and regarded as multidrug-resistant (MDR). Additionally, 32% of the isolates were resistant to all antibiotics tested, and 91% were extensively drug-resistant (XDR). The increased rate of aminoglycoside-resistant A. baumannii in ICU patients, with an increased incidence of aminoglycoside-modifying enzymes of aac (6')-Ib, ant (3″)-I, and aph (2″)-Id. ERIC-PCR has likewise shown an increased level of diversity in A. baumannii isolates. According to the ERIC-PCR patterns, isolates were classified as 4 clusters, while according to the MLVA patterns, isolates were classified as 9 distinct clusters. ERIC-PCR and MLVA assays serve as useful genotyping methods to assess the genetic variety or clonal relatedness of A. baumannii isolates.

High frequency of enterotoxigenic Bacteroides fragilis and Enterococcus faecalis in the paraffin-embedded tissues of Iranian colorectal cancer patients.

BACKGROUND: The association between specific bacteria and colorectal cancer (CRC) has been proposed. Only a few studies have, however, investigated this relationship directly in colorectal tissue with conflicting results. So, we aimed to quantitate Streptococcus gallolyticus, Fusobacterium spp, Enterococcus faecalis and enterotoxigenic Bacteroides fragilis (ETBF) in formalin-fixed and paraffin-embedded (FFPE) colorectal tissue samples of Iranian CRC patients and healthy controls. METHODS: A total of 80 FFPE colorectal tissue samples of CRC patients (n = 40) and healthy controls (n = 40) were investigated for the presence and copy number of above bacterial species using quantitative PCR. Relative quantification was determined using ΔΔCT method and expressed as relative fold difference compared to reference gene. RESULTS: Relative abundance and copy number of E. faecalis and ETBF were significantly higher in CRC samples compared to control group. E. faecalis was more prevalent than ETBF in tumor samples. Frequency of ETBF and E. faecalis in late stages (III/IV) of cancer was significantly higher than early stages (I/II). We did not detect a significant difference in abundance of S. gallolyticus and Fusobacterium spp between two groups. CONCLUSION: Our study revealed the higher concentration of E. faecalis and ETBF in FFPE samples of CRC patients than controls. However, additional investigations on fecal and fresh colorectal cancer tissue samples are required to substantiate this correlation.

Antibiotic susceptibility of human-associated Staphylococcus aureus and its relation to agr typing, virulence genes, and biofilm formation.

BACKGROUND AND OBJECTIVE: Carriage of virulence factors confers some evolutionary benefit to bacteria, which favors the resistant strains. We aimed to analyze whether antibiotic susceptibility of Staphylococcus aureus strains is affected by agr typing, biofilm formation ability, and virulence profiles. METHODS: A total of 123 S. aureus clinical isolates were subjected to antimicrobial susceptibility testing by disk diffusion method, biofilm formation by microtiter plate method, as well as polymerase chain reaction screening to identify virulence genes and the accessory gene regulator (agr) types I-IV. A P value < 0.05 was considered significant. RESULTS: The most prevalent virulence gene was staphyloxanthin crtN, followed by hemolysin genes, capsular cap8H, toxic shock toxin tst, and enterotoxin sea, respectively. Resistant isolates were more commonly found in the agr-negative group than in the agr-positive group. Isolates of agr type III were more virulent than agr I isolates. Strong biofilm producers showed more antibiotic susceptibility and carried more virulence genes than non-strong biofilm producers. Associations were found between the presence of virulence genes and susceptibility to antibiotics. Carriage of the virulence genes and agr was higher in the inpatients; while, resistance and strong biofilms were more prevalent in the outpatients. CONCLUSION: These findings indicated the presence of several virulence factors, biofilm production capacity, agr types and resistance to antibiotics in clinical S. aureus isolates. Considering the importance of S. aureus for human medicine, an understanding of virulence and resistance relationships would help to reduce the impact of S. aureus infections.

The association between fecal enterotoxigenic B. fragilis with colorectal cancer.

BACKGROUND: Enterotoxigenic Bacteroides fragilis (ETBF) is an enterotoxin-producing bacterium that possibily has a role in the occurrence and progression of colorectal cancer (CRC) by modulating the mucosal immune response and inducing epithelial cell changes. The aim of this study was to investigate the frequency of ETBF in stool samples of CRC patients and healthy volunteers. METHODS: A total of 60 stool samples from confirmed CRC patients and 60 stool samples from healthy volunteers with no personal or familial history or diagnosis of colorectal disease were collected. Stool samples were screened for direct detection of B. fragilis using PCR targeting the marker genes of neu and bft. Enterotoxin isotypes bft-1, bft-2 and bft-3 were also detected in B. fragilis positive samples. RESULTS: The frequency of B. fragilis among CRC and control cases was 58.3 and 26.6%, respectively (P < 0.05). The rate of bft gene in CRC cases was significantly higher than in controls (P < 0.05). Also, the presence of bft gene in CRC patients stage III was significantly higher than stages I and II (P < 0.05). Enterotoxin isotype bft-2 was detected with higher frequency among CRC patients than healthy control (P < 0.05). CONCLUSION: Our results show the association between fecal ETBF and CRC, and we suggest that detection of ETBF may be a potential marker for colorectal cancer diagnosis. However, additional investigations on tumor and paired normal tissue samples are required to substantiate this possible correlation.

High incidence of virulence determinants, aminoglycoside and vancomycin resistance in enterococci isolated from hospitalized patients in Northwest Iran.

BACKGROUND: Multidrug resistant (MDR) enterococci are important nosocomial pathogens causing serious problem in hospitalized patients. The aim of present study was to investigate the frequency of high-level aminoglycoside-resistant and vancomycin-resistant enterococci (VRE) and virulence encoding genes in enterococci isolated from hospitalized patients. METHODS: A total of 100 enterococci isolated from urine samples of hospitalized patients with symptomatic urinary tract infections were investigated for antimicrobial susceptibility, the frequency of aminoglycoside and vancomycin resistance genes (including aac (6')-Ie-aph (2")-Ia, aph (3')-IIIa, ant (4')-Ia, aph (2")-Ic, aph (2")-Ib, aph (2")-Id, ant (3″)-III, ant (6')-Ia, vanA, vanB and vanC) and virulence encoding genes (including gelE, PAI, esp, ace, cyl, hyl and sprE). RESULTS: Enterococcus faecalis species was identified as predominant enterococci (69%), followed by "other" Enterococcus species (21%) and E. faecium (10%). Ninety three percent of isolates were resistant to one or more antimicrobial agents, with the most frequent resistance found against tetracycline (86%), ciprofloxacin (73%) and quinupristin-dalfopristin (53%). Gentamicin and streptomycin resistance were detected in 50 and 34% of isolates, respectively. The most prevalent aminoglycoside resistance genes were ant (3″)-III (78%) and aph (3')-IIIa (67%). Vancomycin resistance was detected in 21% of isolates. All E. faecium isolates carried vanA gene, whereas, the vanB gene was not detected in Enterococcus species. The most frequent virulence gene was ace (88.6%), followed by esp (67.1%), PAI (45.5%) and sprE (41.7%). CONCLUSION: Our study revealed the high frequency of gentamycin resistance and VRE in E. faecium isolates, with a high prevalence and heterogeneity of virulence and resistance genes. Due to high frequency of MDR enterococci, it seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of these isolates in hospitals.

Virulence characteristics of multidrug resistant biofilm forming Acinetobacter baumannii isolated from intensive care unit patients.

BACKGROUND: Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide. METHODS: A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes (bap, ompA, csuE, fimH, epsA, blaPER-1, bfmS, ptk, pgaB, csgA, kpsMII), integron characterization and molecular typing based on REP-PCR. RESULTS: All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) (P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates (P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness. CONCLUSION: Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.

Diversity of virulence genes in multidrug resistant Pseudomonas aeruginosa isolated from burn wound infections.

Multidrug resistant Pseudomonas aeruginosa has frequently been reported as the cause of nosocomial outbreaks of burn wound infections. The pathogenesis of P. aeruginosa is partly due to the production of several cell-associated and extracellular virulence factors. A total of 93 P. aeruginosa isolated from burn wound infections were investigated for antimicrobial susceptibility and distribution of virulence genes. All (100%) isolates were resistant to one or more antimicrobial agents. The most frequent resistance found against ampicillin (91.4%), co-trimoxazole (77.4%), gentamicin (68.8%), cefotaxime (50.5%), aztreonam and piperacillin (41.9%). A total of 88 (94.6%) isolates were resistant to at least three different classes of antimicrobial agents and considered as multidrug resistance MDR. All isolates carried at least two or more different virulence genes. The most prevalent virulence gene was toxA (97.8%), followed by plcH (96.7%), phzI (96.7%), exoY (93.1%) and phzII (90.3%). exoU was not detected in P. aeruginosa isolates. The frequency of pilB (17.2%), exoT (20.4%), pilA (24.7%) and phzS/phzH (27.9%) was lower than other virulence genes. Twenty nine (31.2%) isolates had simultaneously 8 virulence genes, 22 (23.7%) isolates had 6 virulence genes and 19 (20.4%) isolates had 7 virulence genes. All MDR isolates carried at least 5 virulence factors. These results indicate a high frequency and heterogeneity of virulence gene profiles among multidrug resistant P. aeruginosa isolates recovered from burn wound infections. Therefore, appropriate surveillance and control measures are essential to prevent the further spread of these isolates in hospitals.

Inhibition of quorum sensing related virulence factors of Pseudomonas aeruginosa by pyridoxal lactohydrazone.

Pseudomonas aeruginosa quorum sensing (QS) system is a cell to cell signaling mechanism that regulates virulence factors and pathogenicity. Therefore, the QS system in P. aeruginosa may be an important target for pharmacological intervention. The present study aimed to investigate the effects of sub-MIC concentrations of (S,E)-2-hydroxy-N-(3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)propane hydrazide (pyridoxal lactohydrazone) against P. aeruginosa QS related virulence factors. We investigated the effect of sub-MIC concentrations of chiral pyridoxal lactohydrazone, which formed by the reaction of chiral lactic acid hydrazide and pyridoxal (one form of Vitamin B6) as bioactive reagents, on virulence factors. Treated PAO1 cultures in the presence of tested compound at 1/4 and 1/16 MIC (32 and 8 µg/mL respectively) showed significant inhibition of virulence factors including motility, alginate and pyocyanin production and susceptibility to H2O2 (P < 0.001). Also, the pyridoxal lactohydrazone showed anti-QS activity in Chromobacterium violaceum CV026 biosensor bioassay. Because of quorum sensing is a promising target for anti-virulence therapy and also important role of LasR regulatory protein in the initiation of P. aeruginosa QS system, we carried out molecular docking for understanding the interactions of pyridoxal lactohydrazone with the LasR receptor. The results of docking study suggested that the pyridoxal lactohydrazone has potential to inhibit the LasR protein. The results indicated that sub-MIC concentrations of this compound exhibited inhibitory effect on P. aeruginosa QS related virulence factors.

Synergistic activity of sub-inhibitory concentrations of curcumin with ceftazidime and ciprofloxacin against Pseudomonas aeruginosa quorum sensing related genes and virulence traits.

Quorum sensing (QS) system in Pseudomonas aeruginosa may be an important target for pharmacological intervention. The present study aimed to investigate the synergetic activity of sub-MIC concentrations of curcumin (C) with ceftazidime (CAZ) and ciprofloxacin (CIP) against P. aeroginusa QS system. We determined the MIC and synergistic activity of C, CAZ and CIP against P. aeroginusa PAO1 using broth microdilution and checkerboard titration methods. The activity of sub-MIC (1/4 and 1/16 MIC) concentrations of C on the QS signal molecules was assessed using a reporter strain assay. The influence of sub-MIC of C, CAZ and CIP alone and in combination on motility and biofilm formation was also determined and confirmed by RT-PCR to test the expression of QS regulatory genes lasI, lasR, rhlI and rhlR. The addition of C decreased the MIC of CAZ and CIP. Curcumin showed synergistic effects with CAZ and additive activity with CIP. Treated PAO1 cultures in the presence of C showed significant reduction of signals C12-HSL and C4-HSL (P < 0.05). Sub-MIC concentrations (1/4 and 1/16 MIC) of C, CAZ and CIP alone and in combination significantly reduced swarming and twitching motilities and biofilm formation. Expression of QS regulatory genes lasI, lasR, rhlI, and rhlR using 1/4 MIC of C, CAZ and CIP alone and in combination was repressed significantly relative to untreated PAO1. Our results indicate that a combination of the sub-MIC concentration of C and CAZ exhibited synergism against P. aeroginusa QS system. This combination could lead to the development of a new combined therapy against P. aeruginosa.

Fabrication of silver nanoparticles-deposited fabrics as a potential candidate for the development of reusable facemasks and evaluation of their performance.

Recently, wearing facemasks in public has been raised due to the coronavirus disease 2019 epidemic worldwide. However, the performance and effectiveness of many existing products have raised significant concerns among people and professionals. Therefore, greater attempts have been focused recently to increase the efficacy of these products scientifically and industrially. In this respect, doping or impregnating facemask fabrics with metallic substances or nanoparticles like silver nanoparticles has been proposed. So, in the present study, we aimed to sonochemically coat silver nanoparticles on the non-woven Spunbond substrates at different sonication times and concentrations to develop antibacterial and antiviral facemask. The coated substrates were characterized using Field Emission Scanning Electron Microscope, Energy Dispersive X-Ray, X-ray diffraction, and Thermogravimetry analysis. The amount of silver released from the coated substrates was measured by atomic absorption spectroscopy. The filtration efficiency, pressure drop, and electrical conductivity of the coated samples were also investigated. The antibacterial activity of fabrics was evaluated against Escherichia coli and Staphylococcus aureus. Cellular viability of samples assessed by MTT and brine shrimp lethality tests. The results revealed that the higher sonication times and precursor concentrations result in a higher and more stable coating, larger particle size, wider particle size distribution, and lower content of released silver. Coated fabrics also revealed enhanced filtration efficiency (against nanosize particles), desired pressure drop, and antibacterial activity without significant cytotoxicity toward HEK 293 cells and Artemia nauplii. As a result, the coated fabrics could find potential applications in the development of facemasks for protection against different pathogenic entities.

Injectable, antibacterial, and oxygen-releasing chitosan-based hydrogel for multimodal healing of bacteria-infected wounds.

Bacterial infection is one of the main challenges of wound healing. It imposes financial and healthcare costs. The emergence of antibiotic-resistant bacteria has increased concerns about this challenge, and made finding alternative solutions a crucial aim. We created a new, antibacterial, multifunctional hydrogel with synergistic chemodynamic and photothermal features for wound-healing applications. We fabricated a chitosan (CT)-based hydrogel containing tannic acid (TA), Fe, and MnO2 nanosheets (CT-TA-Fe-MnO2) via a simple method and characterized it. The antibacterial features (resulting from the production of reactive oxygen species within bacterial cells) and healing ability (via anti-inflammatory and hemostatic features) of the hydrogel were confirmed in vitro. In vivo results revealed the effectiveness of the CT-TA-Fe-MnO2 hydrogel in decreasing the hemostatic time, improving anti-inflammatory effects, and promoting wound healing during 14 days by enhancing the deposition and maturation of collagen fibers without affecting the vital organs. The fabricated CT-TA-Fe-MnO2 hydrogel could be a promising candidate with antibacterial and anti-inflammatory activities suitable for wound-healing applications.

A fabricated hydrogel of hyaluronic acid/curcumin shows super-activity to heal the bacterial infected wound.

High risk of acute morbidities and even mortality from expanding the antibiotics resistant infectious wounds force indefinite efforts for development of high performance wound-healing materials. Herein, we design a procedure to fabricate a hyaluronic acid (HA)-based hydrogel to conjugate curcumin (Gel-H.P.Cur). The highlight of this work is to provide a favorite condition for capturing curcumin while protecting its structure and intensifying its activities because of the synchronization with HA. Accordingly, HA as a major component of dermis with a critical role in establishing skin health, could fortify the wound healing property as well as antibacterial activity of the hydrogel. Gel-H.P.Cur showed antibacterial properties against Pseudomonas aeruginosa (P. aeruginosa), which were examined by bactericidal efficiency, disk diffusion, anti-biofilm, and pyocyanin production assays. The effects of Gel-H.P.Cur on the inhibition of quorum sensing (QS) regulatory genes that contribute to expanding bacteria in the injured place was also significant. In addition, Gel-H.P.Cur showed high potential to heal the cutaneous wounds on the mouse excisional wound model with repairing histopathological damages rapidly and without scar. Taken together, the results strongly support Gel-H.P.Cur as a multipotent biomaterial for medical applications regarding the treatment of chronic, infected, and dehiscent wounds.

Metal-coordination synthesis of a natural injectable photoactive hydrogel with antibacterial and blood-aggregating functions for cancer thermotherapy and mild-heating wound repair.

Photothermal therapy (PTT) is a promising approach for treating cancer. However, it suffers from the formation of local lesions and subsequent bacterial infection in the damaged area. To overcome these challenges, the strategy of mild PTT following the high-temperature ablation of tumors is studied to achieve combined tumor suppression, wound healing, and bacterial eradication using a hydrogel. Herein, Bi2S3 nanorods (NRs) are employed as a photothermal agent and coated with hyaluronic acid to obtain BiH NRs with high colloidal stability. These NRs and allantoin are loaded into an injectable Fe3+-coordinated hydrogel composed of sodium alginate (Alg) and Farsi gum (FG), which is extracted from Amygdalus scoparia Spach. The hydrogel can be used for localized cancer therapy by high-temperature PTT, followed by wound repair through the combination of mild hyperthermia and allantoin-mediated induction of cell proliferation. In addition, an outstanding blood clotting effect is observed due to the water-absorbing ability and negative charge of FG and Alg as well as the porous structure of hydrogels. The hydrogels also eradicate infection owing to the local heat generation and intrinsic antimicrobial activity of the NRs. Lastly, in vivo studies reveal an efficient photothermal-based tumor eradication and accelerated wound healing by the hydrogel.

A photoactive injectable antibacterial hydrogel to support chemo-immunotherapeutic effect of antigenic cell membrane and sorafenib by near-infrared light mediated tumor ablation.

Intravenously administered nanocarriers suffer from off-target distribution, pre-targeting drug leakage, and rapid clearance, limiting their efficiency in tumor eradication. To bypass these challenges, an injectable hydrogel with time- and temperature-dependent viscosity enhancement behavior and self-healing property are reported to assist in the retention of the hydrogel in the tumor site after injection. The cancer cell membrane (CCM) and sorafenib are embedded into the hydrogel to elicit local tumor-specific immune responses and induce cancer cell apoptosis, respectively. In addition, hyaluronic acid (HA) coated Bi2S3 nanorods (BiH) are incorporated within the hydrogel to afford prolonged multi-cycle local photothermal therapy (PTT) due to the reduced diffusion of the nanorods to the surrounding tissues as a result of HA affinity toward cancer cells. The results show the promotion of immunostimulatory responses by both CCM and PTT through the release of inflammatory cytokines from immune cells, which allows localized and complete ablation of the breast tumor in an animal model by a single injection of the hydrogel. Moreover, the BiH renders strong antibacterial activity to the hydrogel, which is crucial for the clinical translation of injectable hydrogels as it minimizes the risk of infection in the post-cancer lesion formed by PTT-mediated cancer therapy.

Injectable Antibacterial Gelatin-Based Hydrogel Incorporated with Two-Dimensional Nanosheets for Multimodal Healing of Bacteria-Infected Wounds.

The design and development of multifunctional injectable hydrogels with high photothermal antibacterial activity and shape adaptability to accelerate bacteria-infected wound healing is of critical importance in clinical applications. In this study, a hybrid hydrogel composed of gelatin, iron, and MnO2 nanosheets was prepared by multiple interactions, including coordinative and hydrogen bonding as well as electrostatic attraction. The introduced MnO2 and Fe components made the hydrogels photothermally and chemodynamically active, thereby endowing them with potent antibacterial capabilities against both Gram-negative and Gram-positive bacteria. Because of the Fenton activity of the hydrogels, they could produce abandoned oxygen, which is highly crucial in the healing process of wounds. They also showed good cytocompatibility and hemocompatibility as well as high hemostatic properties. Moreover, the injectable hydrogels could fill irregular wounds and significantly accelerate bacteria-infected wound healing through decreasing the inflammatory response and increasing blood vessels. These features indicated the promising potential of the multifunctional hydrogel for healing infected full-thickness wounds.

High frequency of enterotoxin encoding genes of Staphylococcus aureus isolated from food and clinical samples.

BACKGROUND: Staphylococcus aureus is recognized as an important cause of food poisoning related to the consumption of raw, undercooked, or mishandled foods worldwide. METHODS: A total of 90 individual meat samples and 200 clinical specimens were collected and investigated the frequency of S. aureus and classical enterotoxin genes. The samples were cultured on Baird-Parker and Mannitol salt agar and subjected for confirmatory biochemical tests and molecular detection of femA, sea, seb, sec, sed, and see genes. RESULTS: A total of 31 (34.5%) meat samples and 81 (40.5%) clinical specimens were positive for the presence of S. aureus. These isolates were detected with slightly higher frequency in clinical specimens than food samples (P> 0.05). Furthermore, the frequency of S. aureus in raw meat (23.4%) was higher than that in cooked meat samples (11.1%) (P< 0.05). Staphylococcal enterotoxin (SE) genes were identified in 18 (58.1%) of 31 meat isolates and 42 (51.8%) of 81 clinical isolates. The frequency of SE genes (except see) in meat isolates was slightly higher than that in clinical isolates (P> 0.05). We found sea and see genes with higher frequency than others in both meat and clinical samples. Furthermore, 55.5% of meat isolates and 38.1% of clinical isolates possessed more than one se gene. CONCLUSION: Detection of enterotoxigenic S. aureus in clinical and raw meat samples shows a probable risk for public health. Therefore, intensive and continuous monitoring of potentially pathogenic S. aureus is strongly recommended in order to evaluate the human health risk arising from food consumption.

Synthesis, characterization and assessment of anti-quorum sensing activity of copper(II)-ciprofloxacin complex against Pseudomonas aeruginosa PAO1.

Quorum sensing (QS) inhibition by metal-antibiotic complexes is a promising strategy for the management and control of multidrug resistant Pseudomonas aeruginosa infections. We investigated the anti-quorum sensing activity of sub-minimum inhibitory concentration (sub-MIC) of copper(II) sulfate pentahydrate-ciprofloxacin (Cu-CIP) complex and free ciprofloxacin (free-CIP) against P. aeruginosa PAO1. Copper-CIP complex was synthesized and its characterization was assessed using spectroscopic methods and single crystal X-ray analysis. The effect of sub-MIC (1/4 and 1/16 MIC) concentrations of Cu-CIP and free-CIP on cell growth, biofilm formation, motility, alginate and pyocyanin production, H2O2 susceptibility and expression of QS circuit genes lasI and lasR in PAO1 was determined. Minimum inhibitory concentration of Cu-CIP complex and free-CIP was determined as 0.125 µg/ml. Copper-CIP complex did not show significant effect on the cell growth at concentrations of 1/4 and 1/16 MIC. However, sub-MIC concentrations (1/4 and 1/16 MIC) of Cu-CIP showed the significant reduction in violacein production, motility, biofilm formation, alginate and pyocyanin production and sensitivity to H2O2 in a concentration dependent manner (P < 0.001). Copper-CIP at the concentration of 1/4 MIC showed the greatest reduction in lasI and lasR transcriptional expression (89.5% and 96.2% respectively). Considering the biological effects of Cu-CIP complex and its inhibitory activity on QS related virulence traits at low concentrations (0.03 and 0.007 µg/ml), it may be used as an effective approach in the management of infections caused by P. aeruginosa.

Inhibitory activity of metal-curcumin complexes on quorum sensing related virulence factors of Pseudomonas aeruginosa PAO1.

The use of metal complexes to reduce or inhibit virulence factors of Pseudomonas aeruginosa is a promising strategy for the management and control of infections caused by this multidrug-resistant pathogen. The present study aimed to investigate the anti-quorum sensing activity of sub-minimum inhibitory concentrations (sub-MIC) of copper(II) sulfate pentahydrate-curcumin complex (Cu-CUR), iron(III) nitrate nonahydrate -curcumin complex (Fe-CUR), zinc(II) chloride-curcumin complex (Zn-CUR) and free curcumin (free-CUR) against P. aeruginosa PAO1. Metal-CUR complexes were synthesized and characterized by spectroscopic methods. The effect of sub-MIC (1/4 and 1/16 MIC) concentrations of metal-CUR complexes and free-CUR on cell growth, biofilm formation, motility, alginate and pyocyanin production, H2O2 susceptibility and expression of lasI and lasR genes in PAO1 was determined. MIC of metal-CUR complexes and free-CUR was determined as 62.5 and 125 µg/ml, respectively. Metal-CUR complexes at concentration of 62.5 µg/ml significantly reduced the cell growth to 1.5%-3.3%. Although we did not measure the anti-QS activity of metal-CUR complexes directly against PAO1, they indicated anti-QS activity in C. violaceum CV026. Copper-CUR complex at the concentration of 1/4 MIC showed the greatest inhibitory effect on swarming and twitching motilities, biofilm formation, alginate and pyocyanin production, sensitivity to H2O2 and reduction in the expression levels of lasI and lasR genes (P < 0.001). Considering the biological effects of Cu-CUR complex and its inhibitory activity on virulence factors, it may be used as an effective compound for treatment and control of infections caused by P. aeruginosa.

Frequency of hemolysin BL and non-hemolytic enterotoxin complex genes of Bacillus cereus in raw and cooked meat samples in Zanjan, Iran.

Food safety has emerged as an important global issue with international trade and public health implications. Bacillus cereus is an important cause of food poisoning worldwide. A total of 200 individual meat samples were collected from meat retail outlets and restaurants and investigated the frequency of B. cereus and hemolysin BL (Hbl), non-hemolytic enterotoxin (Nhe) complex genes. The meat samples were immediately homogenized and cultured on Bacillus cereus selective agar and subjected for confirmatory biochemical tests and molecular detection of gyrB, hblA, hblC, hblD, nheA, nheB and nheC genes. A total of 29 (14.5 %) meat samples were positive for the presence of B. cereus. The frequency of B. cereus in raw meat (14.1 %) was similar to cooked beef samples (15 %) (P >  0.05). Twenty six (89.6 %) isolates carried at least one or more enterotoxin genes. We found nheA (58.6 %) and hblD (51.7 %) genes with higher frequency than others. Hemolysin BL complex genes were found in lower frequency than Nhe complex (P >  0.05). Detection of enterotoxigenic B. cereus in meat samples shows a probable risk for public health. Therefore, the reliable molecular methods for monitoring of potentially pathogenic B. cereus are strongly recommended for the routine food examination.