Antimicrobial effect of silver and gold nanoparticles in combination with linezolid on Enterococcus biofilm

Background and Objectives

In the past few years, application of new antimicrobial e.g. nanoparticles (NPs) to treat infection caused by drug-resistant bacteria has increased. This study aimed to determine antimicrobial property of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) in combination with linezolid on Enterococcus biofilm.

Materials and Methods

A total of forty-eight isolates of Enterococcus spp. were collected and confirmed by PCR method. The synthesis of biocompatible AgNPs was performed, then analyzed by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy. We carried out minimum inhibitory concentration (MIC) and biofilm forming capacity of AgNPs and AuNPs with linezolid.

Results

Twenty-two E. faecium isolates and twentysix E. faecalis investigated in this study. Strong biofilm formation was seen in 12 (25%) of isolates, and others isolates (75%) formed moderate biofilm. AgNPs and Au-NPs size were 26 nm and 20 nm respectively. The MIC of AgNPs was 23.2 μg/ml, and AuNPs were 92.1 μg/ml and the lowest MIC was obtained 2 μg/ml in linezolid. Biofilm formation inhibitory activity by AuNPs + Linezolide and AgNPs + Linezolide 70 to 80 percent increased in average.

Conclusion

The antibiofilm activity of AgNPs and AuNPs increased when both agents were used in combination with linezolid in comparison with each agent alone.

Evaluating the relationship between Helicobacter pylori infection

Introduction

Helicobacter pylori is a gram-negative spiral bacterium that is frequently found in the human stomach. Significant association has been reported between Cytotoxin associated gene A (CagA)- positive Helicobacter pylori strains and coronary heart disease. The aim of the present study is to investigate the carotid intima-media thickness as an indicator of atherosclerosis in people with Helicobacter pylori infection.

Methods

This study was done on patients who underwent upper GI endoscopy and biopsy, and after obtaining conscious consent underwent ultrasound of the right and left carotid arteries for measuring carotid intima-media thickness (CIMT) and blood tests.

Results

In this study, 90 patients who underwent upper GI endoscopy were examined in three groups: negative H. pylori negative, positive cagA and negative cagA. The right, left and average of CIMT in cagA-positive group were significantly higher than the other two groups (p < 0.05). Howerver, the average of CIMT was not significantly different between men and women. Also, the hsCRP average level in positive cagA group was significantly higher than other groups (p < 0.05).

Conclusion

Our findings suggest that there is an increase in CIMT values in patients with H. pylori infection, especially in cases of positive cagA. The positive cagA group showed significantly higher levels of hs-CRP, as a marker of elevated inflammatory response. Therefore, H. pylori infection, especially cagA-positive strains and its associated systemic inflammatory response can be considered as a contributing factor in atherosclerosis and cardiovascular disease.

•

H.pylori infection especially in case of positive CagA⁺ caused the right/left CIMT increase.

•

Higher levels of inflammation in H.pylori, CagA patients and atherosclerosis risk factors couldn’t cause the significant difference.

•

H.pylori infection with positive CagA and its inflammation is an important factor in atherosclerosis and cardiovascular diseases.

The combined effect of stressful factors (temperature and pH) on the expression of biofilm, stress, and virulence genes in Salmonella enterica ser. Enteritidis and Typhimurium

Salmonella enterica is a major food borne pathogen that creates biofilm. Salmonella biofilm formation under different environmental conditions is a public health problem. The present study was aimed to evaluate the combined effects of stressful factors (temperature and pH) on the expression of biofilm, stress, and virulence genes in Salmonella Enteritidis and Salmonella Typhimurium. In this study, the effect of temperature (2, 8, 22.5, 37, 43 °C) and pH (2.4, 3, 4.5, 6, 6.6) on the expression of biofilm production genes (adr A, bap A), virulence genes (hil A, inv A) and the stress gene (RpoS) of S. Enteritidis and S. Typhimurium was evaluated. The response surface methodology (RSM) approach was used to evaluate the combined effect of the above factors. The highest expression of adr A, bap A, hil A, and RpoS gene for S. Typhimurium was at 22 °C-pH 4.5 (6.39-fold increase), 37 °C-pH 6 (3.92-fold increase), 37 °C-pH 6 (183-fold increase), and 37 °C-pH 3 (43.8-fold increase), respectively. The inv A gene of S. Typhimurium was decreased in all conditions. The adr A, bap A, hil A, inv A, and RpoS gene of S. Enteritidis had the highest expression level at 8 °C-pH 3 (4.09-fold increase), 22 °C-pH 6 (2.71-fold increase), 8 °C pH 3 (190-fold increase), 22 °C-pH 4.5 (9.21-fold increase), and 8 °C-pH 3 (16.6-fold), respectively. Response surface methodology (RSM) indicated that the temperature and pH had no significant effect on the expression level of adr A, bap A, hil A, Inv A, and RpoS gene in S. Enteritidis and S. Typhimurium. The expression of biofilm production genes (adr A, bap A), virulence genes (hil A, inv A) and the stress gene (RpoS) of S. Enteritidis and S. Typhimurium is not directly and exclusively associated with temperature and pH conditions.

Anticancer Effect of Enterocin A-Colicin E1 Fusion Peptide on the Gastric Cancer Cell

Cancer is one of the most causes of death all over the world, although improvements in its treatment and recognition. Due to the limitations of common anticancer methods, including surgery, chemotherapy, and radiotherapy, attention has been drawn to other anti-cancer compounds, especially natural peptides such as bacteriocins. In this study, we used a combination of two bacteriocins, colicin E1 and enterocin A, against AGS gastric cancer cell lines. In order to evaluate anticancer properties of fusion peptide, we applied MTT assay, real-time PCR, and flow cytometry tests. This is the first report to show the cell growth inhibitory activity of the enterocin A in combination with colicin E1 against AGS human cancer cells. The results of this study showed that this fusion peptide at a concentration of 60.4 µg/mL and 24 h was able to kill half of the tested cancer cells, and treatment of the cells with this concentration increased the expression of bax and caspase 3 genes and reduced the expression of bacl-2 in 24 h. Flow cytometry analysis of annexin V-FITC/propidium iodide results also showed that our peptide was able to induce apoptosis in treated cells compared with control. Taken together, enterocin A-colicin E1 (ent A-col E1) can be considered as a good candidate for anticancer therapies.

Bacteriocins: New Potential Therapeutic Candidates in Cancer Therapy

Cancer is one of the most important disorders which is associated with high mortality and high costs of treatment for patients. Despite several efforts, finding, designing and developing, new therapeutic platforms in the treatment of cancer patients are still required. Utilization of microorganisms, particularly bacteria has emerged as new therapeutic approaches in the treatment of various cancers. Increasing data indicated that bacteria could be used in the production of a wide range of anti-cancer agents, including bacteriocins, antibiotics, peptides, enzymes, and toxins. Among these anti-cancer agents, bacteriocins have attractive properties, which make them powerful anti-cancer drugs. Multiple lines evidence indicated that several bacteriocins (i.e., colcins, nisins, pediocins, pyocins, and bovocins) via activation/inhibition different cellular and molecular signaling pathways are able to suppress tumor growth in various stages. Hence, identification and using various bacteriocins could lead to improve and introduce them to clinical practices. Here, we summarized various bacteriocins which could be employed as anti-cancer agents in the treatment of many cancers.

Bacterial Etiology and Antibiotic Susceptibility of Conjunctivitis Patients' Isolates in Kashan, Iran

Background

Conjunctivitis is a very common ocular disease, which can be caused by a wide variety of microorganisms. This study was aimed to assess the bacterial etiology and antibiotic susceptibility of conjunctivitis patients' isolates from Central Iran.

Materials and Methods

This study was performed in 180 patients referred to the Department of Ophthalmology in Kashan University with symptoms of conjunctivitis from July 2017 to December 2017. To detect of different bacteria, Gram staining, morphological characterization, pigment production, biochemical characteristics, coagulase test, optochin and PYR tests, oxidase test, and culture on specific media were used. Antibiotic susceptibility of the bacteria isolated was done using the Kirby-Bauer method. Methicillin resistance in staphylococci isolated from the patients was identified using polymerase chain reaction technique.

Results

Of the 195 bacteria isolated, about 81.5% were Staphylococcus epidermidis and Staphylococcus aureus and the remaining 19.5% included other species. In the present study, Pseudomonas aeruginosa was most resistant to ampicillin. In the case of S. epidermidis and S. aureus, the highest resistance was observed against erythromycin and the least resistance was against rifampicin and linezolid.

Conclusion

In this study, S. aureus and S. epidermidis are the most common causes of conjunctivitis in all age groups, however, this condition decreases with age and is also influenced by other factors such as season and weather conditions. The results of this study can be helpful in planning more prudent treatment strategies for patients with conjunctivitis in Kashan.

Molecular analysis and the toxin, MSCRAMM, and biofilm genes of methicillin-resistant Staphylococcus aureus strains isolated from pemphigus wounds: A study based on SCCmec and dru typing

INTRODUCTION

Pemphigus is a chronic autoimmune blistering disease. Pemphigus blisters can damage the natural skin barrier and increase the risk of life-threatening conditions. Colonization of pemphigus wounds with methicillin-resistant Staphylococcus aureus (MRSA) prolongs wound healing and increases mortality rate. Assessing MRSA prevalence, types, and toxin and adhesion genes can facilitate the detection of MRSA strains which cause infections, selection of appropriate treatments, and healing of pemphigus wounds. This study aimed to determine the SCCmec, the direct repeat unit (dru) types (dts), and the toxin, MSCRAMM, and biofilm genes of MRSA strains isolated from pemphigus wounds.

METHODS

In this cross-sectional study, 118 S. aureus isolates were gathered from 118 patients with pemphigus. MRSA detection was performed using the mecA gene. Using the polymerase chain reaction method, all MRSA isolates were assessed for the presence of the sea, seb, sec, tst, eta, pvl, hla, hlb, MSCRAMM, and ica genes. Typing and subtyping were performed through respectively SCCmec typing and dru typing methods. The Bionumerics software was used for analyzing the data and drawing the minimum spanning tree.

FINDINGS

From 118 S. aureus isolates, 51 were MRSA. SCCmec typing revealed the prevalence of SCCmec II with a prevalence of 64.7% (33 out of 51 isolates) and SCCmec III with a prevalence of 35.3% (18 out of 51 isolates). Dru typing indicated seven dts, namely dts 10a, 10g, 10m, 13i, 8h, 8i, and 9ca in two main clusters. The dt9ca was a new dru type and was registered in the dru-typing database (www.dru-typing.org). The prevalence rates of the hla, sea, and sec genes in MRSA isolates were respectively 54.9%, 27.4%, and 1.9%, while the hlb, seb, eta, and pvl genes were not detected at all. Only one MRSA with SCCmec III and dt10a carried the tst encoding gene. MSCRAMM gene analysis revealed the high prevalence of the eno (31.3%) and the fib (21.5%) genes. The prevalence rates of the icaA and icaD biofilm formation genes were 3.9% and 5.8%, respectively. There were no significant differences between the two detected SCCmec types and between the two detected dts clusters respecting the prevalence of the encoding genes of virulence factors and MSCRAMMs.

CONCLUSION

The toxin genes hla and sea are prevalent among MRSA strains with SCCmec II and III isolated from pemphigus wounds. The most prevalent dts are dt10a and dt10g among MRSA with SCCmec III and dt8h and dt8i among MRSA with SCCmec II.

Molecular Epidemiology of Antimicrobial Resistance of Uropathogenic Escherichia coli Isolates from Patients with Urinary Tract Infections in a Tertiary Teaching Hospital in Iran

To characterize the resistance patterns of uropathogenic Escherichia coli (UPEC) in a Tertiary Teaching Hospital in Iran, we conducted a descriptive epidemiology study using molecular techniques. The subjects consisted of patients having acute urinary tract infection, who were enrolled in the study from 2014 to 2017. The antimicrobial susceptibility profile of 101 UPEC isolates was determined by Kirby-Bauer disc diffusion method. Extended spectrum β-lactamase (ESBL) was detected by the double-disk synergy test. Biofilm formation was done using microtiter plates. The presence of virulence genes (pai, pap, hly, traT, pai, cnf-1, sfa, and afa) was evaluated by a PCR. Molecular typing of UPEC E. coli isolates was performed with fimH and multilocus sequence typing (MLST). 70.3% of isolates were multidrug-resistant. 37.6% of isolates were Extended spectrum β-lactamases (ESBLs) producer. Strong biofilm formation was seen in 27.7%. Forty-seven different fimH allelic variants were identified. Among identified fimH allelic variants, the most common types were f1 (18.8%) and f14 (18.8%). ST131 (54.5%) was the most prevalent clonal group significantly correlated with the pai gene. Seven sequence types (STs) were detected only once (ST405, ST410, ST450, ST636, ST648, ST1193, and ST6451). Clonal groups showed no significant differences in terms of antibiotic resistance patterns. There was no significant difference between virulence genes and antibiotic resistance patterns in the studied clonal groups. To our knowledge, the present study is the first study in Iran that investigated the genotypic diversity of UPEC isolates by MLST and fimH typing methods. The two methods might serve as a useful molecular test for surveillance and epidemiological studies of isolates.

Highly efficient novel recombinant L-asparaginase with no glutaminase activity from a new halo-thermotolerant Bacillus strain

Introduction: The bacterial enzyme has gained more attention in therapeutic application because of the higher substrate specificity and longer half-life. L-asparaginase is an important enzyme with known antineoplastic effect against acute lymphoblastic leukemia (ALL). Methods: Novel L-asparaginase genes were identified from a locally isolated halo-thermotolerant Bacillus strain and the recombinant enzymes were overexpressed in modified E. coli strains, Origami^TM B and BL21. In addition, the biochemical properties of the purified enzymes were characterized, and the enzyme activity was evaluated at different temperatures, pH, and substrate concentrations. Results: The concentration of pure soluble enzyme obtained from Origami strain was ~30 mg/L of bacterial culture, which indicates the significant improvement compared to L-asparaginase produced by E. coli BL21 strain. The catalytic activity assay on the identified L-asparaginases (ansA1 and ansA3 genes) from Bacillus sp. SL-1 demonstrated that only ansA1 gene codes an active and stable homologue (ASPase A1) with high substrate affinity toward L-asparagine. The K_cat and K_m values for the purified ASPase A1 enzyme were 23.96^s-1 and 10.66 µM, respectively. In addition, the recombinant ASPase A1 enzyme from Bacillus sp. SL-1 possessed higher specificity to L-asparagine than L-glutamine. The ASPase A1 enzyme was highly thermostable and resistant to the wide range of pH 4.5-10. Conclusion: The biochemical properties of the novel ASPase A1 derived from Bacillus sp. SL-l indicated a great potential for the identified enzyme in pharmaceutical and industrial applications.

Highly efficient novel recombinant L-asparaginase with no glutaminase activity from a new halo-thermotolerant Bacillus strain

Introduction: The bacterial enzyme has gained more attention in therapeutic application because of the higher substrate specificity and longer half-life. L-asparaginase is an important enzyme with known antineoplastic effect against acute lymphoblastic leukemia (ALL).

Methods: Novel L-asparaginase genes were identified from a locally isolated halo-thermotolerant Bacillus strain and the recombinant enzymes were overexpressed in modified E. coli strains, Origami^TM B and BL21. In addition, the biochemical properties of the purified enzymes were characterized, and the enzyme activity was evaluated at different temperatures, pH, and substrate concentrations.

Results: The concentration of pure soluble enzyme obtained from Origami strain was ~30 mg/L of bacterial culture, which indicates the significant improvement compared to L-asparaginase produced by E. coli BL21 strain. The catalytic activity assay on the identified L-asparaginases (ansA1 and ansA3 genes) from Bacillus sp. SL-1 demonstrated that only ansA1 gene codes an active and stable homologue (ASPase A1) with high substrate affinity toward L-asparagine. The K_cat and K_m values for the purified ASPase A1 enzyme were 23.96^s-1 and 10.66 µM, respectively. In addition, the recombinant ASPase A1 enzyme from Bacillus sp. SL-1 possessed higher specificity to L-asparagine than L-glutamine. The ASPase A1 enzyme was highly thermostable and resistant to the wide range of pH 4.5–10.

Conclusion: The biochemical properties of the novel ASPase A1 derived from Bacillus sp. SL-l indicated a great potential for the identified enzyme in pharmaceutical and industrial applications.

Purification of Antibacterial CHAPK Protein Using a Self-Cleaving Fusion Tag and Its Activity Against Methicillin-Resistant Staphylococcus aureus

Therapeutic LysK-CHAP is a potent anti-staphylococcal protein that could be utilized as an antibiotic substitute. Intein-mediated protein purification is a reasonable and cost-effective method that is most recently used for recombinant therapeutic protein production. Intein (INT) is the internal parts of the protein that can be separated from the immature protein during protein splicing process. This sequence requires no specific enzyme or cofactor for separation. INT sequence and their characteristic of self-cleavage by thiol induction, temperature, and pH changes are used for protein purification. The current study presents the expression of CHAP_K262 domain of LysK gene that is fused with INT/chitin-binding sequence while evaluating its purification procedure and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The coding gene sequence of LysK-CHAP (CHAP_K262) in pET22-b was amplified with polymerase chain reaction (PCR); the digested product was then cloned into the pTXB1 vector. Electrophoresis confirmed the cloning accuracy of the gene. The pTXB1-CHAP_K262 plasmid was transformed to the Escherichia coli ER₂₅₆₆ (E. coli ER₂₅₆₆) expression strain and analyzed for expression of the recombinant protein by SDS-PAGE and Western blotting methods. Finally, CHAP_K262 was purified by chitin affinity column using INT tag technology and confirmed by SDS-PAGE. Lytic activity of the purified protein was investigated by disk diffusion method. Cloning of CHAP_K262 into the pTXB1 vector, which comprised INT/chitin-binding sequence, was successfully achieved. The SDS-PAGE data also revealed successful expression of the CHAP_K262-INT fusion protein and Western blotting method validated the accuracy of the protein. Moreover, purification of CHAP_K262 protein was induced by dithiothreitol (DTT) and confirmed by SDS-PAGE. Finally, inhibition zone in MRAS culture medium confirmed antibacterial activity of the protein. Application of intein-mediated antibacterial protein is an appropriate and streamlined method for one-step purification of CHAP_K262 as a therapeutic and antibacterial protein. Self-cleaving tags like intein are cost-effective and could be used as a proper purification method for industrial purposes.

Recombinant Endolysins as Potential Therapeutics against Antibiotic-Resistant Staphylococcus aureus: Current Status of Research and Novel Delivery Strategies

Staphylococcus aureus is one of the most common pathogens of humans and animals, where it frequently colonizes skin and mucosal membranes. It is of major clinical importance as a nosocomial pathogen and causative agent of a wide array of diseases. Multidrug-resistant strains have become increasingly prevalent and represent a leading cause of morbidity and mortality. For this reason, novel strategies to combat multidrug-resistant pathogens are urgently needed. Bacteriophage-derived enzymes, so-called endolysins, and other peptidoglycan hydrolases with the ability to disrupt cell walls represent possible alternatives to conventional antibiotics. These lytic enzymes confer a high degree of host specificity and could potentially replace or be utilized in combination with antibiotics, with the aim to specifically treat infections caused by Gram-positive drug-resistant bacterial pathogens such as methicillin-resistant S. aureus. LysK is one of the best-characterized endolysins with activity against multiple staphylococcal species. Various approaches to further enhance the antibacterial efficacy and applicability of endolysins have been demonstrated. These approaches include the construction of recombinant endolysin derivatives and the development of novel delivery strategies for various applications, such as the production of endolysins in lactic acid bacteria and their conjugation to nanoparticles. These novel strategies are a major focus of this review.

A Novel Chimeric Endolysin with Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus

Cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) and amidase are known as catalytic domains of the bacteriophage-derived endolysin LysK and were previously reported to show lytic activity against methicillin-resistant Staphylococcus aureus (MRSA). In the current study, the in silico design and analysis of chimeric CHAP-amidase model was applied to enhance the stability and solubility of protein, which was achieved through improving the properties of primary, secondary and tertiary structures. The coding gene sequence of the chimeric CHAP-amidase was synthesized and subcloned into the pET-22(+) expression vector, and the recombinant protein was expressed in E. coli BL21 (DE3) strain. Subsequent affinity-based purification yielded ~12 mg soluble protein per liter of E. coli culture. Statistical analysis indicated that concentrations of ≥1 μg/mL of the purified protein have significant antibacterial activity against S. aureus MRSA₂₅₂ cells. The engineered chimeric CHAP-amidase exhibited 3.2 log reduction of MRSA₂₅₂ cell counts at the concentration of 10 μg/mL. A synergistic interaction between CHAP-amidase and vancomycin was detected by using checkerboard assay and calculating the fractional inhibitory concentration (FIC) index. This synergistic effect was shown by 8-fold reduction in the minimum inhibitory concentration of vancomycin. The chimeric CHAP-amidase displayed strong antibacterial activity against S. aureus, S. epidermidis, and enterococcus. However, it did not indicate any significant antibacterial activity against E. coli and Lactococcus lactis. Taken together, these findings suggest that our chimeric CHAP-amidase might represent potential to be used for the development of efficient antibacterial therapies targeting MRSA and certain Gram-positive bacteria.

Sensitivity of levofloxacin in combination with ampicillin-sulbactam and tigecycline against multidrug-resistant Acinetobacter baumannii

BACKGROUND AND OBJECTIVES

The selection of alternative treatment options with antibiotic combinations may be used for successful managing of multidrug-resistant Acinetobacter baumannii. The aim of this study was to determine the synergistic effects of ampicillin-sulbactam combined with either levofloxacin or tigecycline against MDR A. baumannii.

MATERIALS AND METHODS

A total 124 of A.baumannii isolates collected from clinical samples of hospitalized patients which assessed for antibiotic susceptibility using disk diffusion method. E-test was used on 10 MDR A. baumannii isolates to determine the minimum inhibitory concentration (MIC) of ampicillin-sulbactam, levofloxacin and tigecycline. Any synergistic effects were evaluated at their own MIC using E-test assay at 37°C for 24 hours. Synergy was defined as a fractional inhibitory concentration index (FICI) of ≤0.5.

RESULTS

Levofloxacin plus ampicillin-sulbactam combination was found to have synergistic effects (FIC index: ≤0.5) in 90% of the isolates, but there was no synergistic effect for ampicillin-sulbactam/tigecycline and tigecycline/levofloxacin combination. The antagonist effect in 50% of isolates (FIC index: >2) showed in combination of levofloxacin/tigecycline.

CONCLUSION

The emergence of multidrug A. baumannii isolates requires evaluating by combination therapy. The combination of levofloxacin plus a bactericidal antibiotic such as ampicillin-sulbactam is recommended. Results should be confirmed by clinical studies.

Identification and Molecular Characterization of Genes Coding Pharmaceutically Important Enzymes from Halo-Thermo Tolerant Bacillus

Purpose: Robust pharmaceutical and industrial enzymes from extremophile microorganisms are main source of enzymes with tremendous stability under harsh conditions which make them potential tools for commercial and biotechnological applications. Methods: The genome of a Gram-positive halo-thermotolerant Bacillus sp. SL1, new isolate from Saline Lake, was investigated for the presence of genes coding for potentially pharmaceutical enzymes. We determined gene sequences for the enzymes laccase (CotA), l-asparaginase (ansA3, ansA1), glutamate-specific endopeptidase (blaSE), l-arabinose isomerase (araA2), endo-1,4-β mannosidase (gmuG), glutaminase (glsA), pectate lyase (pelA), cellulase (bglC1), aldehyde dehydrogenase (ycbD) and allantoinases (pucH) in the genome of Bacillus sp. SL1. Results: Based on the DNA sequence alignment results, six of the studied enzymes of Bacillus sp. SL-1 showed 100% similarity at the nucleotide level to the same genes of B. licheniformis 14580 demonstrating extensive organizational relationship between these two strains. Despite high similarities between the B. licheniformis and Bacillus sp. SL-1 genomes, there are minor differences in the sequences of some enzyme. Approximately 30% of the enzyme sequences revealed more than 99% identity with some variations in nucleotides leading to amino acid substitution in protein sequences. Conclusion: Molecular characterization of this new isolate provides useful information regarding evolutionary relationship between B. subtilis and B. licheniformis species. Since, the most industrial processes are often performed in harsh conditions, enzymes from such halo-thermotolerant bacteria may provide economically and industrially appealing biocatalysts to be used under specific physicochemical situations in medical, pharmaceutical, chemical and other industries.

Efficacy of probiotics as an adjuvant agent in eradication of Helicobacter pylori infection and associated side effects

The intestinal tract is a host to various types of bacteria that are essential to health. Interactions between intestinal bacteria, i.e. the normal microbiota of the host’s intestine, have been a subject of intensive research, as they may influence disease cycles. Recent studies of selected probiotic species and their therapeutic benefits have suggested a potential efficacy in treatment of several gastrointestinal illnesses, including Helicobacter pylori infection. The increasing evidence from these clinical studies supports the promising role of probiotics in improving the treatment of H. pylori by increasing eradication rates as well as decreasing the adverse effects of current medication therapy. However, many unsolved questions remain which require high quality trials on specific probiotic strains in the future. The main part of this review will focus on the effects of supplementary probiotic products during standard triple H. pylori therapy.

Emerging Carbapenem-Resistant Pseudomonas aeruginosa Isolates Carrying blaIMP Among Burn Patients in Isfahan, Iran

BACKGROUND

Metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa is a significant pathogen in burn patients.

OBJECTIVES

The aim of this study was to determine the prevalence of carbapenem-resistant P. aeruginosa isolates, including those resistant to imipenemase (IMP), in a burn unit in Isfahan, Iran.

PATIENTS AND METHODS

One hundred and fifty P. aeruginosa isolates from burn patients were tested for antibiotic susceptibility by the disc diffusion method in accordance with CLSI guidelines. Production of MBL was identified with the EDTA disk method. DNA was purified from the MBL-positive isolates, and detection of the bla_IMP gene was performed with PCR.

RESULTS

Fifty-seven out of 150 (38%) isolates were multi-drug resistant (MDR), and 93 (62%) were extensively-drug resistant (XDR). Among all isolates, the resistance rate to ciprofloxacin, tobramycin, imipenem, meropenem, amikacin, ceftazidime, and cefepime was higher than 90%, while the resistance rates to piperacillin/tazobactam and aztreonam were 70.7% and 86%, respectively. Colistin and polymyxin B remained the most effective studied antibiotics. All of the imipenem-resistant P. aeruginosa isolates were MBL-positive, and 107 out of 144 (74.3%) of the MBL isolates were positive for the bla_IMP gene.

CONCLUSIONS

The results of this study show that the rate of P. aeruginosa-caused burn wound infections was very high, and many of the isolates were resistant to three or more classes of antimicrobials. Such extensive resistance to antimicrobial classes is important because few treatment options remain for patients with burn wound infections. bla_IMP -producing P. aeruginosa isolates are a rising threat in burn-care units, and should be controlled by conducting infection-control assessments.

A strategy for soluble overexpression and biochemical characterization of halo-thermotolerant Bacillus laccase in modified E. coli

An efficient method was introduced for soluble expression of recombinant laccase (rpCotA(SL-1)) from a newly isolated halo-thermotolerant Bacillus sp. SL-1 in modified Escherichia coli, trxB2/gor2 mutant (Origami™ B (DE3)). The yield of purified soluble laccase in Origami strain under micro-aerobic condition was ∼20mg/L of bacterial culture, showing significant improvement over the laccase produced in E.coli BL21 strain under aerobic condition. The specific activity of 13U/mg for purified laccase produced in micro-aerobic condition was higher than that of 1.07U/mg observed for the purified enzyme obtained in aerobic condition in Origami. The kinetic Km and kcat parameters for laccase-induced oxidation reactions were 46μM and 23s(-1) for ABTS (2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulphonic acid), and 19.6μM and 24s(-1) for SGZ (syringaldazine) substrates, respectively. The rpCotA(SL-1) displayed thermostability at 70°C and tolerance to specified concentrations of NaCl, NaN3, EDTA and SDS as inhibitors. The enzyme was relatively stable in the presence of different concentration of organic solvents, however the residual activity was adversely affected as the dipole moment of the solvents increase. Here we successfully report the production of soluble and functional laccase in Origami at the expression level suitable for industrial application.

Prevalence of CTX-M-Type and PER Extended-Spectrum β-Lactamases Among Klebsiella spp. Isolated From Clinical Specimens in the Teaching Hospital of Kashan, Iran

Background:

Extended-spectrum β-lactamases (ESBLs) is one of the most important mechanisms of resistance to β-lactams especially among Enterobacteriaceae family including Klebsiella spp. Different types of extended-spectrum β-lactamases including CTX-M-type and PER enzymes are identified among gram negative bacteria.

Objectives:

The current study aimed to determine the prevalence of CTX-M-type and PER extended-spectrum β-lactamases among Klebsiella spp. isolated from clinical specimens in the teaching hospital of Kashan, Iran.

Patients and Methods:

One hundred Klebsiella spp. were isolated from clinical specimens of hospitalized patients at Shahid-Beheshti hospital from December 2012 to November 2013. Disk diffusion method was used to determine the susceptibility of these isolates to 14 different antimicrobial agents; disks were purchased from MAST company (United Kingdom). The phenotypic double disk synergy confirmatory test was used to screen the isolates to produce extended-spectrum β-lactamase. DNAs of isolates were extracted using boiling method and PCR assay was used to characterize the bla_CTX-M type and bla_PER genes. The purified PCR products were sent to Macrogen research company (Korea) for sequencing.

Results:

Of the total 100 Klebsiella isolates, %93 was susceptible to imipenem. Resistance to ampicillin, ceftazidime, ceftriaxone, aztreonam and cefotaxime was (92%), (67%), (65%), (64%) and (59%), respectively. The phenotypic confirmatory test (PCT) confirmed that 35% (n = 35) of the isolates were ESBL-producing Klebsiella strains. The prevalence of bla_CTX-M type and bla_RER genes among Klebsiella isolates were 28% (n = 28) and 9% (n = 9), respectively.

Conclusions:

The prevalence of ESBL-producing Klebsiella strains in Shahid-Beheshti hospital in Kashan has increased. The study concluded that there was a high prevalence of the bla_CTX-M type gene among ESBL positive isolates.

Characterization of CTX-M-Type Extend-Spectrum β-Lactamase Producing Klebsiella spp. in Kashan, Iran

CONTEXT

The CTX-M family consists of more than 50 β-lactamases, which are grouped on the basis of sequences into five subtypes including CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9 and CTX-M-25.

OBJECTIVES

The current study aimed to detect subtypes of CTX-M extended-spectrum β-lactamases (ESBLs) among ESBL positive Klebsiella isolates from patients in Kashan, Iran.

MATERIALS AND METHODS

A total of 100 clinical isolates of Klebsiella were collected and the isolates, which showed resistance or reduced susceptibility to cefotaxime, ceftazidime and/or aztreonam by the disk diffusion method were selected. These isolates were identified as ESBL-producing isolates by double disk synergy tests using clavulanic acid, cefotaxime, ceftazidime and aztreonam. The blaCTX-M type determinants were identified by the Polymerase Chain Reaction (PCR) method followed by DNA sequencing.

RESULTS

Of the 100 Klebsiella isolates, 41 (41%) demonstrated resistance or reduced susceptibility to ceftazidime and/or aztreonam and 35% (n = 35) were ESBL-producers. Twenty-eight (8o%) of the ESBL-producing isolates carried the blaCTX-M type genes. Based on PCR assays and sequencing of blaCTX-M genes, CTX-M-1, CTX-M-2 and CTX-M-9 were identified in 21 (60%), 15 (42%) and nine (34%) of these isolates, respectively (GenBank accession numbers KJ803828-KJ803829).

CONCLUSIONS

Our study showed that the frequency of blaCTX-M genes among Klebsiella isolates in our region is at an alarming rate. Also, we found a high prevalence of blaCTX-M-1 β-lactamase in Klebsiella isolates in Kashan.

Expression of Recombinant pET22b-LysK-Cysteine/Histidine-Dependent Amidohydrolase/Peptidase Bacteriophage Therapeutic Protein in Escherichia coli BL21 (DE3)

OBJECTIVES

Bacteriophage-encoded endolysins are a group of enzymes that act by digesting the peptidoglycan of bacterial cell walls. LysK has been reported to lyse live staphylococcal cultures. LysK proteins containing only the cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) domain has the capability to show lytic activity against live clinical staphylococcal isolates, including methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to clone and express LysK-CHAP domain in Escherichia coli BL21 (DE3) using pET22b as a secretion vector. The pET22b plasmid was used, which encoded a pelB secretion signal under the control of the strong bacteriophage T7 promoter.

METHODS

The E. coli cloning strains DH5α and BL21 (DE3) were grown at 37°C with aeration in the Luria-Bertani medium. A plasmid encoding LysK-CHAP in a pET22b backbone was constructed. The pET22b vector containing LysK-CHAP sequences were digested with NcoI and HindIII restriction enzymes. Cloning accuracy was confirmed by electrophoresis. The pET22b-LysK plasmid was used to transform the E. coli strain BL21. Isopropyl β-d-1-thiogalactopyranoside (IPTG) was added to a final concentration of 1mM to induce T7 RNA polymerase-based expression. Finally, western blot confirmed the expression of target protein.

RESULTS

In this study, after double digestion of pEX and pET22b vectors with HindIII and NcoI, LysK gene was cloned into two HindIII and NcoI sites in pET22b vector, and then transformed to E. coli DH5α. Cloning was confirmed with double digestion and analyzed with agarose gel. The recombinant pET22b-LysK plasmid was transformed to E. coli BL21 and the expression was induced by IPTG. The expression was confirmed by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting method. Observation of a 28.5 kDa band confirmed LysK protein expression.

CONCLUSION

In the present study, LysK-CHAP domain was successfully cloned and expressed at the pET22b vector and E. coli BL21 (DE3).

Molecular Characteristics of Nasal Carriage Methicillin-Resistant Coagulase Negative Staphylococci in School Students

Background:

Coagulase-negative staphylococci (CoNS) are opportunistic pathogens. Methicillin resistance is common in CoNS and may play an important role as reservoir of staphylococcal cassette chromosome mec (SCCmec) for Staphylococcus aureus.

Objectives:

The aim of this study was to determine molecular characteristics of nasal carriage of methicillin-resistant coagulase negative staphylococci among students.

Materials and Methods:

MR-CoNS from both nares of students were collected. Resistance to methicillin was determined by cefoxitin (30μg) disk diffusion test. SCCmec typing was performed using multiplex PCR by mec complex classes and ccr genes. Antimicrobial susceptibility profiles were determined on Mueller-Hinton agar according to CLSI.

Results:

A total of 600 consecutive students were enrolled in this study; 430 of whom (71.7%) had CoNS. Seventy-two MR-CoNS strains, 21 (29.2%) S. lugdunensis, 17 (23.6%) S. haemolyticus, 17 (23.6%) S. saprophyticus, 9 (12.5%) S. epidermidis and 8 (11.1%) S. schleiferi were isolated. MR-CoNS rate in nasal carriage was 16.7%. All strains were susceptible to vancomycin. Forty-eight (66.7%) had a single SCCmec type including types I (n = 5), II (n = 4), III (n = 7), IV (n = 19) and V (n = 13), whereas 5 (6.9%) had two types including III + IV (n = 2), III + V (n = 1) and IV + V (n = 2). Nineteen strains (26.4%) were non-typeable for their SCCmec and ccr. Types IV and V SCCmec were associated with S. lugdunensis and S. haemolyticus, respectively.

Conclusions:

SCCmec types IV and V were prevalent in MR-CoNS and few isolates could harbor more than one type.

The Prevalence of Endocervical Chlamydia trachomatis Infection Among Young Females in Kashan, Iran

Background:

Chlamydia trachomatis is one of the major bacterial agents of the sexually transmitted diseases worldwide, especially among young females. There is no data regarding the prevalence of genital Chlamydia infection among young females in Kashan, Iran.

Objectives:

The current study aimed to determine the prevalence of endocervical C. trachomatis infection among females aged 17 - 35 years in Kashan, Iran.

Patients and Methods:

In the current descriptive study, 255 endocervical swab samples were collected from the obstetrics and gynecology clinics of Kashan, Iran from December 2012 to July 2013. Cervical swabs were placed in transport media and sent to the laboratory. To identify C. trachomatis in the samples Polymerase Chain Reaction (PCR) was performed to amplify a sequence in the cryptic plasmid, generating a fragment of about 512base pair. Demographic data was collected considering the relevant risk factors by a standard questionnaire.

Results:

A total of 255 females were tested. The prevalence of genital C. trachomatis was 2.4% (95% confidence interval [CI] 0.54% - 4.26%); 3.2% of the females in the ≤ 25-year-old group were positive versus 1.8% in the 26 - 35-year-old group. The most general presented symptoms of genital C. trachomatis infection were vaginal discharge (66.6%) and lumbar pain (50%). No significant relationships were found between C. trachomatis infection and the risk factors.

Conclusions:

To the authors’ knowledge this is the first study to describe endocervical C. trachomatis infection in this area. The obtained results also emphasized the importance of routine diagnosis of C. trachomatis to control of the infection.

Nasal Carriage and Resistance Pattern of Multidrug Resistant Staphylococcus aureus Among Healthy Children in Kashan, Iran

Background:

Nasal carriage of Staphylococcus aureus is a substantial source of human infections. Detection and treatment of nasal carriage in children with methicillin-resistant and multidrug resistant S. aureus (MRSA and MDRSA, respectively) may be an important modality in prevention of infections.

Objectives:

This study determined the prevalence, antibiotic resistance patterns and risk factors for nasal carriage of MDRSA among healthy children.

Patients and Methods:

This cross-sectional study was carried out on 350 one-month to 14-year-old healthy children in Kashan city, Iran. From all health-care centers, four were chosen by simple random sampling. Nasal samples were cultured in blood agar medium for S. aureus and antibiotic susceptibility profile was determined by disc diffusion and E-test. Risk factors for nasal carriage of MDRSA were also determined.

Results:

A total of 92 (26.3%) S. aureus isolates were obtained, of which 33 (35.9%) were MRSA and 27 (29.3%) were MDRSA. Of MRSA strains, 19 (70.4%) were MDRSA. S. aureus isolates showed 52.2% resistance to cephalothin, 33.7% to co-trimoxazole, 26.1% to clindamycin, 26.1% to ciprofloxacin, 4.3% to vancomycin, and 35.9% to oxacillin. The risk factors for nasal carriage of MDRSA were antibiotic usage during the last three months (P = 0.006), family size of more than four members (P = 0.044), and parental smoking (P = 0.045).

Conclusions:

MDRSA was not uncommon among healthy children in Kashan and prevention of its spread in the population is judicious.

Risk Factors for Methicillin Resistant Staphylococcus aureus Nasal Colonization of Healthy Children

Background:

Nasal colonization of healthy children with Staphylococcus aureus is an important risk factor for different infections. Detection of colonized individuals with methicillin resistant S. aureus (MRSA) and its eradication is the proper prevention strategy for infection spread in the community and health-care centers.

Objectives:

The aim of this study was to determine the prevalence, associated risk factors and antibiotic resistance pattern among healthy children who were nasal carriers of S. aureus.

Patients and Methods:

This cross-sectional study was conducted on 350 one month to 14-year-old healthy children living in Kashan/Iran. The nasal specimens were cultured in blood agar medium for S. aureus. Positive cultures were evaluated for cephalothin, co-trimoxazole, clindamycin, ciprofloxacin, oxacillin and vancomycin susceptibility by the disc diffusion method and E-test. Risk factors for nasal carriage of S. aureus and MRSA were evaluated.

Results:

Frequency of S. aureus nasal carriage was 92 from 350 cases (26.2%), amongst which 33 (35.9%) were MRSA. Isolates indicated an overall resistance of 52.2% to cephalothin, 33.7% to co-trimoxazol, 26.1% to ciprofloxacin, 26.1% to clindamycin, 35.9% to oxacillin and 4.3% to vancomycin. Factors associated with MRSA nasal carriage included gender (P value 0.001), age of less than four years (P value 0.016), number of individuals in the family (P value < 0.001), antibiotic use (P value < 0.001) and admission (P value < 0.001) during the previous three months, parental smoking (P value < 0.001) and sleeping with parents (P value 0.022).

Conclusions:

Age of less than four years, male sex, family size being more than four, antibiotic use and admission during the previous three months, parental smoking and sleeping with parents were independent risk factors for nasal colonization with MRSA.

The Helicobacter pylori resistance rate to clarithromycin in Iran

BACKGROUND

Clarithromycin is the most commonly suggested antibiotic in Helicobacter pylori eradication regimens. Increasing antibiotic resistance rate to clarithromycin is the main reason for therapeutic failure. The resistance is associated with mutations in the 23S rRNA gene.

AIM

The purpose of this study was to determine the clarithromycin resistance rate of isolated H. pylori strains from referral patients in Kashan, Iran.

METHODS

In total 95 H. pylori strains isolated from gastric mucosa of 246 patients with different clinical signs underwent gastroscopy in Kashan, Iran in 2013. The Epsilometer test was used to determine the minimum inhibitory concentrations (MICs) of clarithromycin (CLR) in isolated H. pylori strains. Occurrence of mutation in 23S rRNA gene of clarithromycin-resistant strains was investigated with polymerase chain reaction-sequencing method.

RESULTS

Antibiotic susceptibility pattern showed that 32 strains (33.7%) were resistant to clarithromycin (MICs ≥1 μg/ml), 33.7% were intermediate resistant, while 31 of H. pylori strains (32.6%) were susceptible. The 23S rRNA gene mutations at positions A2143G and A2142G were detected in H. pylori clarithromycin-resistant strains.

CONCLUSION

The resistance rate to clarithromycin in Iran is high. H. pylori clarithromycin-resistant strains were not associated with sex, age, and disease. The A2143G mutation in clarithromycin-resistant H. pylori strains was the predominant finding.

Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA, babA2, and oipA genotypes in patients with upper gastrointestinal diseases

BACKGROUND AND OBJECTIVES

Helicobacter pylori has been strongly associated with peptic ulcer diseases, chronic gastritis, ulcers, and reported as a risk factor for gastric cancer, too. The vaculating cytotoxin (vacA), the cytotoxin associated genes (cagA), the induced by contact with epithelium factor antigen (iceA gene), blood adhesion binding antigen (babA2), and outer membrane protein oipA have been described as different virulence factors of H. pylori. The aim of this study was to investigate the prevalence of the vacA, cagA, cagE, iceA, babA2 and oipA genotypes of H. pylori isolates from patients with upper gasterointestinal problem or dyspepsia.

MATERIAL AND METHODS

H. pylori isolated from endoscopic biopsies obtained from 222 studied patients. PCR was done only on cultured positive samples. The vacA alleles, cagA, cagE, iceA, babA2 and oipA genotypes were determined by PCR.

RESULTS

The isolation rate of H. pylori strains from culture of gastric biopsies was 16.7%. The vacA alleles s1, s2, m1 and m2 were detected in 20 (54.1%), 14 (37.8%), 9 (24.3%) and 23 (62.2%) isolates, respectively. VacA s1c genotype was detected in 70.3% of isolates. s1m2 was the most frequent vacA allelic combination in the examined H. pylori strains. The cagA gene was detected in 62.2%, cagE in 40.5%, iceA1 in 48.6%, iceA2 in 16.2%, oipA in 81.1% (95% CI: 0.0902-0.1798) and babA2 in 94.6% (95% CI: 0.113- 0.207). A significant correlation was observed between vacAs1 and cagA genotypes (P<0.008), vacAs1/cagE (P=0.001), vacAs2/cagA (P<0.047), and vacAs2/cagE (P=0.016) with Non-ulcer dyspepsia; but there were not observed any correlation between other virulence markers.

CONCLUSION

No significant correlation was found between the existence of vacA, cagA, cagE, iceA, babA2, and oipA genes with peptic ulcer diseases and non-ulcer dyspepsia groups of studied patients.

Phylogenetic and biochemical characterization of a new halo-thermotolerant, biofilm-forming Bacillus from Saline Lake of Iran

In this study, five halotolerant Bacillus isolates from Aran-Bidgol Saline Lake in Iran were identified from saline environments. Screening of the bacteria led to the identification of a unique halo-thermotolerant Bacillus. On the basis of genetic and phenotypic data, this isolate was closely related to Bacillus licheniformis. But isolated Bacillus can be distinguished from B. licheniformis by salt tolerance, 16S rDNA sequence and some different physicochemical properties. Thus, suggested that the isolate was not the known Bacillus. Optical density analysis indicated strong biofilm formation for this strain. Also this isolate exhibited average tolerance to 1-25 mM concentrations of zinc and was sensitive to all concentrations of nickel. In biosurfactant production assay, this Bacillus exhibited the high activity for semi-quantitative oil displacement test (3.14 +/- 0.02 cm2) and evaluated positive for drop-collapse test and hemolytic activity. Moreover, amylase, protease and DNase enzymes produced in presence of 10-20% salt of medium. Therefore, identified Bacillus could supply potential microbial materials for bioremediation purposes and biotechnological applications.

Beijing genotype and other predominant Mycobacterium tuberculosis spoligotypes observed in Mashhad city, Iran

PURPOSE

The purpose of this study was to understand the molecular epidemiology of tuberculosis in Khorasan province of Iran was studied by spoligotyping 113 Mycobacterium tuberculosis isolates. The spoligotyping results were in comparison to the word Spoligotyping Database of Institute Pasteur de Guadeloupe (SpolDB4). Spoligotyping data from Iran has rarely been described and there is limited information on the major circulating clades of M. tuberculosis in Iran.

MATERIALS AND METHODS

Spoligotyping was performed on 113 M. tuberculosis isolates from Mashhad patients between November 2004 and September 2005.

RESULTS

The study found 57 spoligopatterns. 17 clusters and 32 true orphan genotype. The biggest cluster with 13 isolates had not been previously reported. The Beijing genotype was seen in eight (7.1%) isolates.

CONCLUSIONS

Genotyping and Spoligotyping gives a unifying framework for both epidemiology and evolutionary analysis of M. tuberculosis populations.

Increasing resistant coagulase negative staphylococci in bovine clinical mastitis

The aim of this study was to determine Coagulase Negative Staphylococci (CNS) and other bacteria for their resistance to antimicrobial agents approved for the control of pathogens involved in clinical bovine mastitis. This descriptive study was done on 106 milk samples obtained from clinical mastitis in dairy cattle husbandry from April 2006 through August 2006 in Kashan, Iran. From the total of 106 milk samples collected from clinical mastitis, 96 (90.6%) lead to positive culture. Coagulase negative Staphylococci isolated in 51 out of 96 samples (53.1%), Staphylococcus aureus isolated in 21 out of 96 (21.9%), gram negative bacilli isolated in 14 out of 96 (14.6%) and Enterococci isolated in 4 (4.2%). The highest rate of resistant CNS observed to penicillin (56.6%) and the highest rate of sensitivity to enrofloxacin 100%, followed by kanamycin, streptomycin and neomycin, 92.2, 82.3 and 82.3%, respectively. The highest rate of resistance S. aureus exhibited to penicillin (66.6%); while the highest rate of sensitivity showed to trimethoprim-sulphamethoxasole (81%), followed by kanamycin and enrofloxacin both at 76.2%. The highest rate of resistance gram negative bacilli exhibited to ampicillin and erythromycin at 71.4%. Their highest rate of sensitivity observed to enrofloxacin (78.6%), followed by kanamycin, (71.4%). In recent years, CNS is emerging as important minor mastitis pathogens and can be the cause of substantial economic losses. The high resistance rate to penicillin and other antibiotics found in this study emphasize the importance of identification of CNS when a bovine clinical mastitis is present.

Antimicrobial resistance among Escherichia coli strains isolated from healthy and septicemic chickens

There is a clear association between heavy antimicrobial consumption in poultry industry and the recovery of resistant bacteria. This was a case-control study of 396 E. coli strains isolated from clinically affected broiler chickens and 132 strains from healthy controls to compare the antimicrobial resistance rates. Antimicrobial resistance testing of 525 avian E. coli strains isolated in Kashan-Iran showed very high levels of resistance to 11 antimicrobials tested, especially to trimethoprim-sulfamethoxazole (98.7%) and to ciprofloxacin (69.7%). The prevalence rate of resistant E. coli to ciprofloxacin and erythromycin in the samples isolated from chickens with colibacillosis was significantly higher than healthy controls. In addition, to prevent the emergence of cross-resistance with human enteric pathogens, controlled use of these antimicrobial agents in veterinary practice is recommended.