Communal living by bacteria and the pathogenesis of urinary tract infections

Plausible Drug Targets in the Streptococcus mutans Quorum Sensing Pathways to Combat Dental Biofilms and Associated Risks

Streptococcus mutans, a Gram positive facultative anaerobe, is one among the approximately seven hundred bacterial species to exist in human buccal cavity and cause dental caries. Quorum sensing (QS) is a cell-density dependent communication process that respond to the inter/intra-species signals and elicit responses to show behavioral changes in the bacteria to an aggressive forms. In accordance to this phenomenon, the S. mutans also harbors a Competing Stimulating Peptide (CSP)-mediated quorum sensing, ComCDE (Two-component regulatory system) to regulate several virulence-associated traits that includes the formation of the oral biofilm (dental plaque), genetic competence and acidogenicity. The QS-mediated response of S. mutans adherence on tooth surface (dental plaque) imparts antibiotic resistance to the bacterium and further progresses to lead a chronic state, known as periodontitis. In recent years, the oral streptococci, S. mutans are not only recognized for its cariogenic potential but also well known to worsen the infective endocarditis due to its inherent ability to colonize and form biofilm on heart valves. The review significantly appreciate the increasing complexity of the CSP-mediated quorum-sensing pathway with a special emphasis to identify the plausible drug targets within the system for the development of anti-quorum drugs to control biofilm formation and associated risks.

Prostatic calculi influence the antimicrobial efficacy in men with chronic bacterial prostatitis

We studied the efficacy of culture-specific antibiotic therapy for chronic bacterial prostatitis (CBP) patients with or without prostatic calculi. This study included 101 patients (21-62 years old) who met the consensus criteria for CBP (National Institutes of Health category II). According to the results of transrectal ultrasonography (TRUS), all patients were divided into two groups: Group 1, CBP with prostatic calculi, n=39; Group 2, CBP without prostatic calculi, n=62. All patients received optimal antimicrobial therapy for 4 weeks and followed up for a minimum of 3 months (range: 3-8 months). In addition to expressed prostatic secretions (EPS) and urine culture, all patients were asked to complete the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and the subjective global assessment (SGA). The microbiological eradication rate at the end of treatment were 32/39 (82.1%) and 54/62 (87.1%), while the rates for continued eradication at the end of study were 17/39 (43.6%) and 45/62 (72.6%) in Group 1 and Group 2 (P<0.01), respectively. We observed a decrease in the total NIH-CPSI score median values from 24 to 19 in Group 1 and from 24 to 11 in Group 2. The pain subscore (P<0.01), urinary sunscore (P<0.05) and quality of life (QoL; P<0.05) as well as the total NIH-CPSI score (P<0.01) were significantly improved after antimicrobial treatment in Group 2 compared to Group 1. Response, defined as a decrease of the NIH-CPSI total score by at least 50%, was seen in Group 1 versus Group 2 in 38.5% and 58.1% (P<0.01), respectively. Our results showed that prostatic calculi influence the antimicrobial efficacy in men with CBP. There was a noticeable decrease in the cure rate of CBP patients with prostatic calculi due to relapse after antimicrobial therapy.

Quenching the quorum sensing system: potential antibacterial drug targets

Emergence of antibiotic and multi-drug resistant pathogenic bacteria has created the need for new drugs and drug targets. During pathogenesis bacteria release signals which regulate virulence and pathogenicity related genes. Such bacteria co-ordinate their virulent behaviour in a cell density dependent phenomenon termed as quorum sensing (QS). In contrast, microbes interfere with QS system by quenching the signals, termed quorum quenching (QQ). As a consequence of disrupted QS, pathogens become susceptible to antibiotics and drugs. In this article, the biodiversity of organisms with potential to quench QS signals and the use of QQ molecules as antibacterial drugs have been reviewed.

Antimicrobial drug resistance

This chapter provides an overview of our current understanding of the mechanisms associated with the development of antimicrobial drug resistance, international differences in definitions of resistance, ongoing efforts to track shifts in drug susceptibility, and factors that can influence the selection of therapeutic intervention. The latter presents a matrix of complex variables that includes the mechanism of drug action, the pharmacokinetics (PK) of the antimicrobial agent in the targeted patient population, the pharmacodynamics (PD) of the bacterial response to the antimicrobial agent, the PK/PD relationship that will influence dose selection, and the integrity of the host immune system. Finally, the differences between bacterial tolerance and bacterial resistance are considered, and the potential for non-traditional anti-infective therapies is discussed.

Eliminating biofilm from ureteral stents: the Holy Grail

PURPOSE OF REVIEW

Biofilms continue to be a major limiting factor in the long-term use of ureteral stents, promoting the development of chronic infections and antibiotic resistance and encrustation. Apart from stent removal in conjunction with antibiotic therapy, there is currently no treatment proven successful for completely eradicating a biofilm-related infection, highlighting the need for continued research in this area.

RECENT FINDINGS

Research continues to focus mainly on biofilm prevention, specifically the development of novel coatings comprising antibacterial, antifouling or bacterial signalling compounds. Notably, all three strategies have generated candidate coatings showing recent success both in vitro and in vivo.

SUMMARY

Despite the current lack of a completely biofilm-resistant device, coating or treatment strategy, continued research into the causation of bacterial biofilm formation and the continued development of novel antibacterial, antifouling and antibiofilm compounds is promising. Future work should be aimed at more rigorous testing of candidate coatings from both physical and bacterial challenge standpoints as well as increased in-vivo investigation via clinical trials.

Novel strategies to combat bacterial virulence

PURPOSE OF REVIEW

Incidences of antimicrobial-resistant infections have increased dramatically over the past several decades and are associated with adverse patient outcomes. Alternative approaches to combat infection are critical and have led to the development of more specific drugs targeted at particular bacterial virulence systems or essential regulatory pathways. The purpose of this review is to highlight the recent developments in antibacterial therapy and the novel approaches toward increasing our therapeutic armory against bacterial infection.

RECENT FINDINGS

Although classic antibiotic development is not occurring rapidly, alternative therapeutics that target specific bacterial virulence systems are progressing from the discovery stage through the Food and Drug Administration approval process. Here we review novel antibodies that target specific virulence systems as well as a variety of newly discovered small molecules that block bacterial attachment, communication systems (quorum sensing) or important regulatory processes associated with virulence gene expression.

SUMMARY

The success of novel therapeutics could significantly change clinical practice. Furthermore, the complications of collateral damage due to antibiotic administration, for example, suprainfections or decreased host immunity due to loss of synergistic bacterial communities, may be minimized using therapeutics that specifically target pathogenic behavior.