Increasing Antimicrobial Resistance: Therapeutic Implications for Enterococcal Infections

Bacillus subtilis WB800N alleviates diabetic wounds in mice by regulating gut microbiota homeostasis and TLR2

OBJECTIVE

This study aims to investigate the effect of Bacillus subtilis WB800N on diabetic wounds.

METHODS

Hematoxylin & eosin (H&E) staining was used to observe the healing of skin wounds. Collagen deposition was assessed by Masson staining. Western blotting and qRT-PCR were used to detect vascular endothelial-related factors (VWF), CD31, TLR2, NLRP3, ASC, and Caspase-1 expression. 16S rDNA sequencing detected microbiota distribution. The concentrations of IL-1β and IL-37 were measured by ELISA. Apoptosis was measured by the TUNEL assay.

RESULTS

Compared with the control group, the wound healing was delayed in diabetic mice. The wound area in the Bacillus subtilis group decreased more significantly than the diabetic wounds group. H&E staining showed that Bacillus subtilis WB800N promoted wound healing and increased re-epithelialization. Masson staining showed that Bacillus subtilis WB800N increased collagen deposition in diabetic wounds mice. Bacillus subtilis WB800N upregulated VWF and CD31 protein expression in diabetic wounds mice. The 16S rDNA results showed that Bacillus subtilis WB800N reduced the diversity of the gut microbiota of diabetic wounds mice and regulated the microbial composition. At the genus level, Bacillus subtilis WB800N reduced the relative abundance of Muribaculaceae and CG-005 in diabetic wounds mice, while increasing the relative abundance of Lactobacillus. Bacillus subtilis WB800N increased the expression of TLR2, NLRP3, ASC, and Caspase-1. Bacillus subtilis WB800N increased the concentrations of IL-1β and IL-37 in serum. Bacillus subtilis WB800N upregulated cell apoptosis. The TLR2 antagonist Sparstolonin B (SsnB) reduced the expression of TLR2, NLRP3, ASC, Caspase-1, IL-1β, and IL-37 and the apoptosis in diabetic wounds mice, while the combined intervention of Bacillus subtilis and SsnB reversed the effect of SsnB treatment alone.

CONCLUSION

Bacillus subtilis WB800N alleviated diabetic wounds healing by regulating gut microbiota homeostasis and TLR2.

SIGNIFICANCE AND IMPACT OF RESEARCH

Our findings might provide potential therapeutic targets for diabetic wounds.

Detection of Bacteriuria by Canine Olfaction

UTIs are a significant medical problem and can lead to life-threatening complications. In this study, five dogs were taught to detect bacteriuria. The dogs' sensitivity (> 99%) and specificity (> 90%) remained the same when samples were diluted to 0.1%.

Background. Urinary tract infections (UTIs) are a significant medical problem , particularly for patients with neurological conditions and the elderly. Detection is often difficult in these patients, resulting in delayed diagnoses and more serious infections such as pyelonephritis and life-threatening sepsis. Many patients have a higher risk of UTIs because of impaired bladder function, catheterization, and lack of symptoms. Urinary tract infections are the most common nosocomial infection; however, better strategies are needed to improve early detection of the disease.

Methods. In this double-blinded, case-control, validation study, we obtained fresh urine samples daily in a consecutive case series over a period of 16 weeks. Dogs were trained to distinguish urine samples that were culture-positive for bacteriuria from those of culture-negative controls, using reward-based clicker and treat methods.

Results. Samples were obtained from 687 individuals (from 3 months to 92 years of age; 86% female and 14% male; 34% culture-positive and 66% culture-negative controls). Dogs detected urine samples positive for 100 000 colony-forming units/mL Escherichia coli (N = 250 trials; sensitivity 99.6%, specificity 91.5%). Dilution of E coli urine with distilled water did not affect accuracy at 1% (sensitivity 100%, specificity 91.1%) or 0.1% (sensitivity 100%, specificity 93.6%) concentration. Diagnostic accuracy was similar to Enterococcus (n = 50; sensitivity 100%, specificity 93.9%), Klebsiella (n = 50; sensitivity 100%, specificity 95.1%), and Staphylococcus aureus (n = 50; sensitivity 100%, specificity 96.3%). All dogs performed with similarly high accuracy: overall sensitivity was at or near 100%, and specificity was above 90%.

Conclusions. Canine scent detection is an accurate and feasible method for detection of bacteriuria.

Clonal structure of Enterococcus faecalis isolated from Polish hospitals: characterization of epidemic clones

To study the population structure of Enterococcus faecalis from Polish hospitals, 291 isolates were typed by pulsed-field gel electrophoresis and a novel multilocus sequence typing scheme (P. Ruiz-Garbajosa et al., J. Clin. Microbiol. 44:2220-2228, 2006). The isolates originated from geographically widespread medical institutions and were recovered during a 10-year period (1996 to 2005) from different clinical sources. The analysis grouped the isolates into five epidemic and 71 sporadic clones. The importance of the previously identified global clonal complexes CC2 and CC9 was corroborated by our findings that two of the Polish epidemic clones, A and J, were classified into these clonal complexes (CCs). However, the two most predominant clones, C (ST40) and F (CC87), did not cluster in the aforementioned CCs and may represent novel epidemic CCs. These clones may have emerged in Central Europe. Clone F, carrying glycopeptide resistance determinants of VanA or VanB phenotypes, caused several outbreaks in hematology units and appeared to be the most prevalent clone in recent years in Poland. Antimicrobial susceptibility testing and additional tests for pathogenicity-related phenotypes (hemolysin and gelatinase production) and genes (asa1 and esp) were performed to further characterize these epidemic clones. Multidrug resistance, glycopeptide resistance, presence of asa1, and production of hemolysin appeared to be statistically significant features related to epidemicity. Production of gelatinase was significant for two of the epidemic clones, whereas presence of the esp gene was not specific for the epidemic clones.

Understanding drug ototoxicity: molecular insights for prevention and clinical management

Ototoxicity is a trait shared by aminoglycoside and macrolide antibiotics, loop diuretics, platinum-based chemotherapeutic agents, some NSAIDs and antimalarial medications. Because their benefits in combating certain life-threatening diseases often outweigh the risks, the use of these ototoxic drugs cannot simply be avoided. In this review, the authors discuss some of the most frequently used ototoxic drugs and what is currently known about the cell and molecular mechanisms underlying their noxious effects. The authors also provide suggestions for the clinical management of ototoxic medications, including ototoxic detection and drug monitoring. Understanding the mechanisms of drug ototoxicity may lead to new strategies for preventing and curing drug-induced hearing loss, as well as developing new pharmacological drugs with less toxic side effects.

A systematic approach to diabetic foot infections

Foot infection is the most common reason for hospitalization and subsequent lower extremity amputation among persons with diabetes. Foot ulceration caused by diabetic neuropathy, trauma, and peripheral vascular disease can lead to a limbor life-threatening infection. The optimum treatment of these potentially devastating conditions depends on a multidisciplinary approach that addresses the related or underlying disorders and thus ensures proper wound healing and a positive outcome. In addition to antibiotic therapy, severe soft-tissue or bone infections may necessitate surgical treatment, including drainage, débridement, and vascular reconstruction. Initial (empiric) antibiotic therapy should provide coverage against staphylococci and streptococci and should be revised according culture results. Antibiotic therapy is not indicated in clinically noninfected wounds. The duration of antibiotic treatment can range from 1 week for mild infections to 6 weeks or more for residual osteomyelitis and severe deep tissue infections. Aggressive (and sometimes repeated or staged) surgical intervention and appropriate antibiotic therapy can reduce the likelihood of a major amputation and the duration of hospitalization.

Analysis of daptomycin efficacy and breakpoint standards in a murine model of Enterococcus faecalis and Enterococcus faecium renal infection

Daptomycin efficacy against clinical isolates of Enterococcus faecalis, Enterococcus faecium, and a lab-derived daptomycin-resistant isolate of E. faecalis was investigated in a mouse model of renal infection. The daptomycin MICs against these enterococci ranged from 0.5 to 50 micro g/ml. The objective of this study was to determine the relationship between the MICs of drugs against E. faecalis and E. faecium and the level of daptomycin exposure needed to evaluate the drug's efficacy. Correlating the required therapeutic exposures of mice with the exposures achieved clinically allowed us to project enterococcal breakpoint values. Mice pretreated with carrageenan were infected intravenously with 3 x 10(8) to 4 x 10(8) CFU of E. faecalis or E. faecium. Daptomycin (5 to 50 mg of drug/kg of body weight) or saline control was administered 4 h postinfection and continued once daily for 2 days (three total doses). On day 4, infected kidneys were harvested, homogenized, and dilution plated. Efficacy was defined as a > or = 2-log(10) (99%) reduction in bacterial burden in infected kidneys. At clinically relevant dosages and exposures (area under the curve, 400 to 600 microg.hr/ml), daptomycin demonstrated similar and marked efficacy against all clinical enterococcal isolates tested. Daptomycin achieved efficacy with comparable doses against both vancomycin-sensitive (MIC, < or = 4 microg/ml) and -resistant enterococcal strains tested. Efficacy was also established against the lab-derived daptomycin-resistant E. faecalis isolate. In this murine renal infection model, clinically relevant exposures of daptomycin were effective against E. faecalis and E. faecium strains for which MICs were < or = 8 microg/ml. These murine efficacy data for daptomycin, along with surveillance data and human pharmacokinetic exposures achieved, suggest a breakpoint concentration value of < or = 8 microg/ml (susceptible) and > or = 16 microg/ml (resistant) for daptomycin against E. faecium and E. faecalis.

Antibiotic resistance

Through billions of years of evolution, microbes have developed myriad defense mechanisms designed to ensure their survival. This protection is readily transferred to their fellow life forms via transposable elements. Despite very early warnings, humans have chosen to abuse the gift of antibiotics and have created a situation where all microorganisms are resistant to some antibiotics and some microorganisms are resistant to all antibiotics. When antibiotics are used, six events may occur with only one being beneficial: when the antibiotic aids the host defenses to gain control and eliminate the infection. Alternatively, the antibiotic may cause toxicity or allergy, initiate a superinfection with resistant bacteria, promote microbial chromosomal mutations to resistance, encourage resistance gene transfer to susceptible species, or promote the expression of dormant resistance genes.

Treatment of Staphylococcus epidermidis ventriculo-peritoneal shunt infection with linezolid

Gram-positive bacterial meningitis frequently complicates ventriculo-peritoneal (VP) shunts used for hydrocephalus. Linezolid, an oxazolidinone, is active against Gram-positive cocci, and has excellent CSF penetration. We present a 22-year-old woman who was cured of a Staphylococcus epidermidis VP shunt infection via shunt removal and intravenous linezolid.