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The biofilm formation by various pathogens causes chronic infections and poses severe threats to industry, healthcare, and society. They can form biofilm on surfaces of medical implants, heart valves, pacemakers, contact lenses, vascular grafts, urinary catheters, dialysis catheters, etc. These biofilms play a central role in bacterial persistence and antibiotic tolerance. Biofilm formation occurs in a series of steps, and any interference in these steps can prevent its formation. Therefore, the hunt to explore and develop effective anti-biofilm strategies became necessary to decrease the rate of biofilm-related infections. In this review, we highlighted and discussed the current therapeutic approaches to eradicate biofilm formation and combat drug resistance by anti-biofilm drugs, phytocompounds, antimicrobial peptides (AMPs), antimicrobial lipids (AMLs), matrix-degrading enzymes, nanoparticles, phagebiotics, surface coatings, photodynamic therapy (PDT), riboswitches, vaccines, and antibodies. The clinical validation of these findings will provide novel preventive and therapeutic strategies for biofilm-associated infections to the medical world. [ABSTRACT FROM AUTHOR]

The use of constructed wetlands (CWs) is one of the best options to treat wastewater. In CWs, microorganisms play a major role in the degradation of organic pollutants but the concentration of nutrients, surfactant, and aeration (NSA) in oil-contaminated water is one of the factors that affect the persistence and metabolic functioning of hydrocarbon-degrading microorganisms. In the present investigation, the influence of the addition of NSA on the persistence of the augmented bacteria, copy of (alkane hydroxylase gene) alkB gene, and its expression level in the water, soil, and plants of CWs were evaluated. The CWs mesocosms were developed by the vegetation of Typha latifolia and Cyperus laevigatus and inoculated with the bacterial consortium (Pseudomonas putida TYRI39, Acinetobacter junii TYRH47, Acinetobacter sp. CYRH17, Pseudomonas sp. CYSI27, and Pseudomonas sp. TYRH42). The mesocosms were provided with nutrients (20 mg l− 1 N, 2.6 mg l− 1 P, and 16.4 mg l− 1 K) in liquid form, surfactant Tween-20 (0.2%, v/v) in liquid form, and aeration (≥ 7.0 ± 1 mg l− 1 DO) using aeration pump. The addition of NSA in CWs enhanced the persistence and metabolic functioning of the inoculated bacteria in the water, rhizospheric soil, and plants. The maximum hydrocarbon removal (97%) was observed in the water treated by CWs having C. laevigatus, bacteria, and NSA, and it is correlated with the copy numbers of alkB and its expression level. The application of NSA in CWs not only improved bacterial persistence and catabolic gene expression but also increased plant development and hydrocarbon removal. [ABSTRACT FROM AUTHOR]

The threat of antibiotic-resistant bacteria is increasing worldwide. Bacteria utilize persistence and resistance to survive antibiotic stress. For a long time, persistence has been studied only under laboratory conditions. Hence, studies of bacterial persistence are limited. Recently, however, the high incidence of infection relapses caused by persister cells in immunocompromised patients has emphasized the importance of persister research. Furthermore, persister pathogens are one of the causes of chronic infectious diseases, leading to the overuse of antibiotics and the emergence of antibiotic-resistant bacteria. Therefore, understanding the precise mechanism of persister formation is important for continued use of available antibiotics. In this review, we aimed to provide an overview of the persister studies published to date and the current knowledge of persister formation mechanisms. Recent studies of the features and mechanisms of persister formation are analyzed from the perspective of the nature of the persister cell. [ABSTRACT FROM AUTHOR]

The phenomenon of bacterial persistence, also known as non-inherited antibiotic tolerance in a part of bacterial populations, was described more than 70 years ago. This type of tolerance contributes to the chronization of infectious diseases, including tuberculosis. Currently, the emergence of persistent cells in bacterial populations is associated with the functioning of some stress-induced molecular triggers, including toxin–antitoxin systems. In the presented review, genetic and metabolic peculiarities of persistent cells are considered and the mechanisms of their occurrence are discussed. The hypothesis of the origin of persister cells based on bistability, arising due to the non-linear properties of a coupled transcription–translation system, was proposed. Within this hypothesis, the phenomenon of the bacterial persistence of modern cells is considered as a result of the genetic fixation of the phenotypic multiplicity that emerged in primitive cells in the process of neutrally coupled co-evolution (genetic drift of multiple neutrally coupled mutations). Our hypothesis explains the properties of persister cells, as well as their origin and "ineradicable" nature. [ABSTRACT FROM AUTHOR]

Synanthropic flies have been implicated in the rapid dissemination of antibiotic-resistant bacteria and resistance determinants in the biosphere. These flies stably harbor a considerable number of bacteria that exhibit resistance to various antibiotics, but the mechanisms underlying this phenomenon remain unclear. In this study, we investigated the persistence of antibiotic-resistant bacteria in the digestive tract of houseflies and green bottle flies, using Proteus mirabilis as a model microorganism. One resistant strain carried the blaTEM and aphA1 genes, and another carried a plasmid containing qnrD gene. Quantitative PCR and 454 pyrosequencing were used to monitor the relative abundance of the Proteus strains, as well as potential changes in the overall structure of the whole bacterial community incurred by the artificial induction of Proteus cultures. Both antibiotic-resistant and -sensitive P. mirabilis strains persisted in the fly digestive tract for at least 3 days, and there was no significant difference in the relative abundance of resistant and sensitive strains despite the lower growth rate of resistant strains when cultured in vitro. Therefore, conditions in the fly digestive tract may allow resistant strains to survive the competition with sensitive strains in the absence of antibiotic selective pressure. The composition of the fly-associated bacterial community changed over time, but the contribution of the artificially introduced P. mirabilis strains to these changes was not clear. In order to explain these changes, it will be necessary to obtain more information about bacterial interspecies antagonism in the fly digestive tract. [ABSTRACT FROM AUTHOR]

Persistent urinary tract infections (UTIs) present a common and challenging problem for both primary care and urologists. They are either the result of bacterial reinfection or persistence, and the management varies depending on the underlying cause. Appropriate investigations are crucial in ruling out any underlying urinary tract abnormalities and identifying the causative organism. We review the underlying pathophysiology and up-to-date management strategies available to the practising urologist. [ABSTRACT FROM AUTHOR]

Two families of specific inhibitors of type C lysozyme (Ivy and PliC) secreted from the periplasmic space are known in enterobacteria. Microbial capacity for distant lysozyme inactivation (antilysozyme activity) is most pronounced in the strains and species carrying homologues of the pliC gene. The pliC homologue localized in a ∼200-kb megaplasmid of Klebsiella pneumoniae was shown to differ significantly in the amino acid composition of the coded polypeptide. Similar to the Salmonella enterica pliC homologue, it possesses a detachable signal part and contains identical functionally critical amino acids of the active center of the inhibitor. Antilysozyme activity of the pliC-positive K. pneumoniae strains was observed at the level corresponding to the highest values found in pliC-positive S. enterica. High level of the antilysozyme activity in K. pneumoniae strains containing the plasmid pliC homologue was found in all studied strains, unlike S. enterica strains carrying the known chromosomal pliC homologue. [ABSTRACT FROM AUTHOR]

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Bacterial respiratory tract colonization predisposes critically ill patients to intensive care unit (ICU)-acquired infections. It is unclear to what extent systemic antibiotics affect colonization persistence. Persistence of respiratory tract colonization, and the effects of systemic antibiotics hereon, were determined in a cohort of ICU patients. Clinical and microbiological data were collected from 715 admitted mechanically ventilated ICU patients with bacterial growth documented in respiratory tract samples. First day of colonization, persistence of colonization and antibiotic effects hereon were analyzed for six groups of pathogens: Pseudomonas aeruginosa, Acinetobacter species, Enterobacteriaceae, Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae. Systemic antibiotics were grouped into ‘effective’ and ‘ineffective’ antibiotics, based on in-vitro susceptibility data for the relevant bacteria. The effects of antibiotics were quantified as relative risk (RR) of bacterial persistence in the absence of effective antibiotics. Persistence of colonization differed significantly between pathogens, ranging from 4 days (median) for H. influenzae and Strep. pneumoniae to 8 days for P. aeruginosa. Systemic antibiotics were administered on 7,102 (61%) of patient days. Antibiotic use was associated with non-persistence for all pathogens, except Acinetobacter species and P. aeruginosa. RR for non-persistence (as compared to ineffective or no antibiotics) ranged from 3.1 (95% CI 1.4–6.6) for H. influenzae to 0.5 (0.3–1.0) for Acinetobacter species. In mechanically ventilated patients, persistence dynamics of bacterial respiratory tract colonization, and the effects of (in-vitro) effective antibiotics hereon, are pathogen-specific. [ABSTRACT FROM AUTHOR]

Purpose. We have investigated the efficacy of colistin and ciprofloxacin, free or bound to polyalkylcyanoacrylate nanoparticles, for the targeting and eradication of Salmonella persisting in the organs of the mononuclear phagocyte system. Methods. A model of persistent S. typhimurium infection was developed in C57BL/6 mice using IV inoculation of the plasmid-cured strain C53. Results. In vivo and ex vivoexperiments showed that the persisting bacteria seem to evolve to a nongrowing state during experimental salmonellosis. In vivo treatment with free or nanoparticle-bound colistin did not significantly reduce the number of viable Salmonella C53, either in the liver or the spleen of infected mice. In contrast, in vivo treatment with ciprofloxacin led to a significant decrease of bacterial counts in the liver whatever the stage of infection and the form used. However, none of the treatments were able to sterilize the spleen or the liver. In ex vivo experiments, colistin was only active against bacteria recovered during the early phase of infection, whereas ciprofloxacin exerted its activity at all times postinfection. Conclusions. We suggest that the micro-environment in which the bacterial cells persist in vivo probably causes dramatic changes in their susceptibility to antimicrobial agents. [ABSTRACT FROM AUTHOR]