Biofilms are communities of microorganisms that are formed on and attached to living or nonliving surfaces and are surrounded by an extracellular polymeric material. Biofilm formation enjoys several advantages over the pathogens in the colonization process of medical devices and patients' organs. Unlike planktonic cells, biofilms have high intrinsic resistance to antibiotics and sanitizers, and overcoming them is a significant problematic challenge in the medical and food industries. There are no approved treatments to specifically target biofilms. Thus, it is required to study and present innovative and effective methods to combat a bacterial biofilm. In this review, several strategies have been discussed for combating bacterial biofilms to improve healthcare, food safety, and industrial process.

Background P. aeruginosa is considered as one of the most important pathogens, and high antibiotic resistance to P. aeruginosa has become an alarming concern. This study attempts to further improve curcumin solubility and stability by producing the involved nanoparticle and investigate the effect of this nanoparticle on those virulence genes of P. aeruginosa in pathogenicity and biofilm formation. Methods In this study, the curcumin nanoparticles were synthesized and characterized, and the antibacterial and antibiofilm effects of Nano-curcumin and curcumin were investigated by microdilution broth and microtiter plate, respectively. In addition, cytotoxic effect of Nano-curcumin on human epithelial cell lines (A549) was determined. The effects of Nano-curcumin on P. aeruginosa virulence genes, mexD, mexB, and mexT (efflux pumps), lecA (adhesion), nfxB (negative regulator of MexCD-OprJ), and rsmZ (biofilm formation) were determined using real-time quantitative PCR. Results Synthesized Nano-curcumins were soluble in water, which inhibited the growth of multidrug-resistant (MDR) P. aeruginosa at 128 µg/mL, whereas it was inhibited at 256 µg/mL for soluble curcumin in DMSO. Sub-inhibitory concentrations of Nano-curcumin reduced biofilm formation and, at 64 μg/mL, disrupted 58% of the established bacterial biofilms. In addition, curcumin nanoparticle downregulated the transcription of virulence genes except nfxB and exerted no cytotoxic effect on human epithelial cell lines (A549). Conclusions Results suggest that Nano-curcumin could be potentially used to reduce P. aeruginosa virulence and biofilm. However, in vivo studies with respect to an animal model are necessary to validate these results.

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In this study, we focused on the emergence of extensively drug-resistant (XDR), pandrug-resistant (PDR), and hypervirulent Klebsiella pneumoniae (hvKP) in Iran. During 2018 to 2020 a total of 52 K. pneumoniae isolates were collected from different clinical specimens. The hvKP isolates were identified by PCR amplification of virulence and capsular serotype-specific genes. Hypermucoviscous K. pneumoniae (hmKP) were identified by string test. Carbapenem-resistant hvKP (CR-hvKP), multidrug-resistant hvKP (MDR-hvKP), extensively drug-resistant hvKP (XDR-hvKP), and pandrug-resistant hvKP (PDR-hvKP) were determined by disc diffusion method, Carba-NP test and PCR method. XDR-hvKP isolates were typed by multilocus sequence typing (MLST). Among all K. pneumoniae isolates 14 (26.9%) were identified as hvKP and 78.6% (11/14) of them were hmKP however, none of the classic K. pneumoniae (cKP) isolates were hmKP. The predominant capsular serotype of hvKP was K2 (42.85%) followed by K1 (35.71%). The prevalence of MDR-hvKP, XDR-hvKP and PDR-hvKP isolates were 6 (42.9%), 5 (35.7%) and 1 (7.1%), respectively. ESBL production was found in 85.7% of hvKP isolates and most of them carried bla TEM gene (78.6%) and 6 isolates (42.9%) were CR-hvKP. Among hvKP isolates, 1 (7.1%), 2 (14.3%), 3 (21.4%), 8 (28.6%), and 11 (78.6%) carried bla NDM-6, bla OXA-48, bla CTX-M, bla SHV, and bla TEM genes, respectively. According to MLST analysis, 2, 1, 1, and 1 XDR-hvKP isolates belonged to ST15, ST377, ST442, and ST147, respectively. The occurrence of such isolates is deeply concerning due to the combination of hypervirulence and extensively drug-resistance or pandrug-resistance.

Background We evaluated the distribution of carbapenem and colistin resistance mechanisms of clinical E. coli and K. pneumoniae isolates from Iran. Methods 165 non-duplicate non-consecutive isolates of K. pneumoniae and E. coli were collected from hospitalized patients admitted to Iran's tertiary care hospitals from September 2016 to August 2018. The isolates were cultured from different clinical specimens, including wound, urine, blood, and tracheal aspirates. Antibiotic susceptibility testing was performed by disc diffusion and microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) guideline. The presence of extended spectrum β-lactamases (ESBLs) genes, carbapenemase genes, as well as fosfomycin resistance genes, and colistin resistance genes was also examined by PCR-sequencing. The ability of biofilm formation was assessed with crystal violet staining method. The expression of colistin resistance genes were measured by quantitative reverse transcription-PCR (RT-qPCR) analysis to evaluate the association between gene upregulation and colistin resistance. Genotyping was performed using the multi-locus sequencing typing (MLST). Results Colistin and tigecycline were the most effective antimicrobial agents with 90.3% and 82.4% susceptibility. Notably, 16 (9.7%) isolates showed resistance to colistin. Overall, 33 (20%), 31 (18.8%), and 95 (57.6%) isolates were categorized as strong, moderate, and weak biofilm-producer, respectively. Additionally, blaTEM, blaSHV, blaCTX-M, blaNDM-1, blaOXA-48-like and blaNDM-6 resistance genes were detected in 98 (59.4%), 54 (32.7%), 77 (46.7%), 3 (1.8%), 17 (10.30%) and 3 (1.8%) isolates, respectively. Inactivation of mgrB gene due to nonsense mutations and insertion of IS elements was observed in 6 colistin resistant isolates. Colistin resistance was found to be linked to upregulation of pmrA-C, pmrK, phoP, and phoQ genes. Three of blaNDM-1 and 3 of blaNDM-6 variants were found to be carried by IncL/M and IncF plasmid, respectively. MLST revealed that blaNDM positive isolates were clonally related and belonged to three distinct clonal complexes, including ST147, ST15 and ST3299. Conclusions The large-scale surveillance and effective infection control measures are also urgently needed to prevent the outbreak of diverse carbapenem- and colistin-resistant isolates in the future.

Staphylococcus aureus is one of the gram positive bacteria that has created many problems in treatment. The antibiotic resistance is an important problem and debatable topic in the world. In recent years, because of overuse of antibiotics and transition of resistance genes, frequency of resistant staphylococcal infections, are increasing. Clindamycin inductive resistance causes failure in treatment. The aim of current study is detection of clindamycin inductive resistance S. aureus isolates among patients admitted to Tehran hospitals by multiplex PCR. A total of 80 isolates of S. aureus were collected from hospitalized patients in Tehran. The antibiotic susceptibility tests were applied by MIC and disk diffusion methods. The identification of clindamycin inductive resistance isolates was performed by D-zone test. To detection of ermA, ermB, ermC and mecA genes, multiplex PCR was administrated. In current experiment, among 80 isolates, resistance rate to erythromycin and clindamycin were 70% and 45% respectively. By D-zone test, 15 samples were positive. The frequency of ermA, ermB and ermC genes in S. aureus isolates were 5%, 7.5% and 10% respectively. The results of this study demonstrated that the antibiotic resistance is a main problem in patient's treatment. By identification of resistant isolates and apply appropriate treatment, can be somewhat prevent from outspread of resistant isolates.

Gene expression regulation plays a critical role in host-pathogen interactions, and RNAs function is essential in this process. miRNAs are small noncoding, endogenous RNA fragments that affect stability and/or translation of mRNAs, act as major posttranscriptional regulators of gene expression. miRNA is involved in regulating many biological or pathological processes through targeting specific mRNAs, including development, differentiation, apoptosis, cell cycle, cytoskeleton organization, and autophagy. Deregulated microRNA expression is associated with many types of diseases, including cancers, immune disturbances, and infection. miRNAs are a vital section of the host immune response to bacterial-made infection. Bacterial pathogens suppress host miRNA expression for their benefit, promoting survival, replication, and persistence. The role played through miRNAs in interaction with host-bacterial pathogen has been extensively studied in the past 10 years, and knowledge about these staggering molecules' function can clarify the complicated and ambiguous interactions of the host-bacterial pathogen. Here, we review how pathogens prevent the host miRNA expression. We briefly discuss emerging themes in this field, including their role as biomarkers in identifying bacterial infections, as part of the gut microbiota, on host miRNA expression.

A major challenge in the treatment of infections has been the rise of extensively drug resistance (XDR) and multidrug resistance (MDR) in Acinetobacter baumannii. The goals of this study were to determine the pattern of antimicrobial susceptibility, blaOXA and carO genes among burn-isolated A. baumannii strains. In this study, 100 A. baumannii strains were isolated from burn patients and their susceptibilities to different antibiotics were determined using disc diffusion testing and broth microdilution. Presence of carO gene and OXA-type carbapenemase genes was tested by PCR and sequencing. SDS-PAGE was done to survey CarO porin and the expression level of carO gene was evaluated by Real-Time PCR. A high rate of resistance to meropenem (98%), imipenem (98%) and doripenem (98%) was detected. All tested A. baumannii strains were susceptible to colistin. The results indicated that 84.9% were XDR and 97.9% of strains were MDR. In addition, all strains bore blaOXA-51 like and blaOXA-23 like and carO genes. Nonetheless, blaOXA-58 like and blaOXA-24 like genes were harbored by 0 percent and 76 percent of strains, respectively. The relative expression levels of the carO gene ranged from 0.06 to 35.01 fold lower than that of carbapenem-susceptible A. baumannii ATCC19606 and SDS – PAGE analysis of the outer membrane protein showed that all 100 isolates produced CarO. The results of current study revealed prevalence of blaOXA genes and changes in carO gene expression in carbapenem resistant A.baumannii.