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.

No abstract

Background:Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients.Objectives:The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients.Materials and Methods:This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing.Results:In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%).Conclusions:The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections.

Since the level of antimicrobial resistance in Bacteroides fragilis has increased, monitoring the antimicrobial susceptibility could be necessary. The objectives of this study were to (i) investigate the prevalence of species, the occurrence of reduced antimicrobial susceptibility (E‐test method), and antibiotic resistance genes in the B. fragilis group and (ii) evaluate the prevalence of enterotoxigenic B. fragilis and the distribution of bft gene subtypes in hospitalized patients. As many as 475 isolates out of 250 stool samples were detected to be B. fragilis group by using conventional biochemical tests (API‐32A system) and multiplex‐PCR. In addition, 48.2%, 13.9%, 76.6%, and 1.2% of B. fragilis group isolates were resistant (according to EUCAST breakpoint) to piperacillin‐tazobactam, meropenem, clindamycin, and metronidazole, respectively. Six metronidazole‐resistant strains were isolated; B. fragilis (n: 3), B. thetaiotaomicron, B. vulgates, and B. ovatus. The presence of the cfiA, cepA, ermF, and nim genes was observed in 3.8%, 15.9%, 34.1%, and 0.7% of the B. fragilis isolates, respectively. One hundred thirty‐two B. fragilis isolates (27.8%)and 21 B  fragilis isolates (15.9%) turned out to be bft gene positive by multiplex‐PCR; eleven isolates (52.4%) harbored bft‐1, eight isolates (38%) harbored bft‐2 isotypes, and two isolates (9.5%) harbored bft‐3 isotype (16.66%). These bacteria harbor antimicrobial resistance genes that could be transferred to other susceptible intestinal strains. Further investigations on lineage analysis are needed for a better understanding of these bacteria in Iran.

Scan to discover onlineBackground & Objective: This study aims to isolate a lytic bacteriophage against planktonic Enterococcus faecalis V583 culture and evaluate its ability to disrupt and inhibit biofilm.Methods: An anti-E. faecalis phage was isolated from sewage and visualized by electron microscopy, the vB_EfsS_V583 (V583) host range was determined by spot test on 13 E. faecalis clinical strains .Inhibition and degradation experiments were designed to investigate the effect of phage on biofilm. In the inhibition and degradation assay, biofilms were formed in the presence and absence of phage, respectively . Finally, crystal violet method tested the effect of phage on biofilm.Results: Phage V583 belongs to the Siphoviridae family and can infect all E. faecalis strains. Antibacterial activity has been shown to degrade and inhibit biofilm produced by V583. The study results showed that phage v583 is more efficient in biofilm inhibition than biofilm degradation. In both assays, phage-treated wells' absorption is less than untreated wells. These results were confirmed by Colony-forming unit reduction in the treated biofilm. Conclusion:The anti-biofilm activity showed that phage therapy using phage V583 might be an alternative tool to remove E. faecalis biofilms.