Nowadays the most important problem in the treatment of bacterial infections is the appearance of MDR (multidrug-resistant), XDR (extensively drug-resistant) and PDR (pan drug-resistant) bacteria and the scarce prospects of producing new antibiotics. There is renewed interest in revisiting the use of bacteriophage to treat bacterial infections. The practice of phage therapy, the application of phages to treat bacterial infections, has been around for approximately a century. Phage therapy relies on using lytic bacteriophages and purified phage lytic proteins for treatment and lysis of bacteria at the site of infection. Current research indicates that phage therapy has the potential to be used as an alternative to antibiotic treatments. It is noteworthy that, whether phages are used on their own or combined with antibiotics, phages are still a promising agent to replace antibiotics. So, this review focuses on an understanding of challenges of MDR, XDR, and PDR bacteria and phages mechanism for treating bacterial infections and the most recent studies on potential phages, cocktails of phages, and enzymes of lytic phages in fighting these resistant bacteria.

Antimicrobial peptides (AMPs) or host defense peptides (HDPs) are vital components of human innate defense system targeting human‐related bacteria. Many bacteria have various mechanisms interfering with AMP activity, causing resistance to AMPs. Since AMPs are considered as potential novel antimicrobial drugs, understanding the mechanisms of bacterial resistance to direct killing of AMPs is of great significance. In this review, a comparative overview of bacterial strategies for resistance to direct killing of various AMPs is presented. Such strategies include bacterial cell envelope modification, AMP degradation, sequestration, expelling, and capsule.

Background & Objective: Since the symptoms of Brucellosis are often atypical and nonspecific, using clinical signs alone to diagnose brucellosis is not advised; therefore, the diagnosis relies predominantly on laboratory testing. Currently, molecular, serological, and microbiological methods are used for diagnosis of this disease. In this study we examined ELISA, PCR and serum agglutination (SAT) methods on human patient serum samples. Methods: A total of 100 serum samples were collected from suspected patients. Fifty serum samples gave a positive result with the Wright test. The ELISA method was first employed on all samples for the detection of IgG and IgM antibodies against Brucella . Subsequently, the rapid PCR methodology was used to identify presence of Brucella genome in 500 µL of each serum sample. The B4/B5 primer pair was used for PCR‌ amplification. Results: Out of the 100 serum samples obtained from patients with suspected brucellosis, 50 samples tested positive by SAT and displayed high titers of 1/160. Of these 50 positive samples, 49 samples were positive as per the ELISA test whereas one sample tested negative. The PCR test was conducted on all 100 serum samples and results showed that the 45 serum samples that gave a positive agglutination test were also positive by PCR. Conclusions: Various laboratory methods have been used or introduced for the detection of Brucella . Molecular methods such as PCR, a rapid and sensitive method for detection of bacteria, have also been reported. Based on the results of this study, we propose that the simultaneous use of serology and molecular techniques has the potential to overcome limitations of detection thereby enabling the selection of appropriate treatment for the patient.

Background Escherichia coli accounts for 70–95% of community-acquired urinary tract infections (UTIs). Recently, there has been an increase in the prevalence of extended-spectrum β-lactamase (ESBL) in the community which required an accurate identification for better management. Therefore, the current study was performed to determine the antimicrobial resistance pattern, investigate ESBL phenotypes and genotypes (blaCTX-M, bla TEM and bla SHV genes) and determine the phylogenetic groups among ESBL-positive isolates from outpatients. Methods One hundred and eighty-three positive urine samples were collected from 4450 outpatient clinic attendees. Antibiotic susceptibility was determined and ESBL phenotype screening was carried out using disk diffusion agar and combination disk techniques, respectively. The assessment of the presence of the blaCTX-M, bla TEM and blaSHV genes and phylogenetic grouping were performed using the polymerase chain reaction (PCR) method. Results Out of 183 E. coli isolates, 59 (32.2%) showed a positive ESBL phenotype. The prevalence of ESBL-producing E. coli was higher in males (57.4%). Fifty-seven of the ESBL-producing strains carried at least one of the β-lactamase genes (bla CTX-M, bla TEM, bla SHV). Phylotyping of multi-drug resistant isolates indicated that the isolates belonged to B2, A and D phylogroups. Analysis of resistance patterns among these phylogroups revealed that 74.4%, 55.3% and 29.7% of the isolates in the B2 group were resistant to trimethoprim-sulfamethoxazole, ciprofloxacin and gentamicin, respectively. Most of the strains in the phylogroup B2 carried the bla CTX-M gene. Conclusions All the ESBL-producing isolates were placed in one of the four phylogenetic groups. The presence of CTX-M and resistance to quinolones were more frequent in B2 strains than in non-B2 strains.

Introduction: The extensive drug-resistant (XDR) Pseudomonas aeruginosa (P. aeruginosa) causes a range of infections with high mortality rate, which inflicts additional costs on treatment. The use of nano-biotechnology-based methods in medicine has opened a new perspective against drug-resistant bacteria. The aim of this study was to evaluate the effectiveness of the AgNO3 nanoparticles alone and conjugated with imipenem (IMI) to combat extensively drug-resistant P. aeruginosa. Methods: Antibiotic susceptibility was carried out using disc diffusion method. Detection of different resistant genes was performed using standard polymerase chain reaction (PCR). The chemically synthesized AgNO 3 particles were characterized using scanning electron microscope (SEM), dynamic light scattering (DLS) and X-ray diffraction (XRD) methods. Fourier transform infrared spectroscopy (FTIR) was accomplished to confirm the binding of AgNO 3 with IMI. The microdilution broth method was used to obtain minimum inhibitory concentration (MIC) of AgNO 3 and IMI-conjugated AgNO 3. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was carried out on L929 cell line to study the cytotoxicity of nanoparticles. The data were analyzed by Eta correlation ratio and chisquare (X 2) test. Results: Analysis of the antibiotic resistance pattern showed that 12 (24%) isolates were XDR, and MIC values of IMI were between 64 and 128 μg/mL. Frequency of SHV, TEM, CTX M, IMP, VIM, OPR, SIM, SPM, GIM, NDM, VEB, PER, KPC, OXA, intI, intII, and intIII genes were 29 (58%), 26 (52%), 26 (52%), 32 (64%), 23 (46%), 43 (86%), 3 (6%), 6 (12%), 3 (6%), 4 (8%), 7 (14%), 6 (12%), 18 (36%), 4 (8%), 19 (38%), 16 (32%), and 2 (4%), respectively. The XRD, SEM, DLS, and FTIR analysis confirmed the synthesis of AgNO 3 nanoparticles and their conjugation with IMI. The AgNO 3 nanoparticles had antimicrobial activity, and their conjugation with IMI showed enhanced effectiveness against XDR isolates. The synthesized AgNO 3 showed no cytotoxic effects. Conclusion: The results suggest that IMI-conjugated AgNO 3 has a strong potency as a powerful antibacterial agent against XDR P. aeruginosa.