The effect of minocycline on Candida albicans

The Efficacy and Safety of Minocycline-Containing Quadruple Therapies Against Helicobacter pylori Infection: A Retrospective Cohort Study

Background

Minocycline, a derivative of tetracycline, has anti-Helicobacter pylori (H. pylori) properties and can be used to treat H. pylori infection. However, only a few randomized controlled trials (RCTs) have investigated the efficacy of minocycline-containing quadruple therapy (MCQT) in treating H. pylori infection. This study aimed to determine the efficacy and safety of MCQT and investigate the factors influencing both aspects.

Methods

This was a retrospective cohort study. Patients diagnosed with H. pylori infection between January 1, 2022, and July 31, 2023 at. The primary outcome was the eradication rate of H. pylori, and the secondary outcome was the number and type of adverse events.

Results

A total of 828 patients were included in this study. The overall H. pylori eradication rate among the included patients at 95% confidence interval (CI) (Range 0.864 to 0.907) was 88.53%. The H. pylori eradication rate for patients who received MCQT regimen as the primary therapy was 92.28% (95% CI: 0.901-0.945), significantly higher than that of patients who received MCQT as rescue therapy (80.81%; 95% CI: 0.761-0.855, P=0.003). Adverse events, including dizziness, abdominal distension, diarrhea, nausea, abdominal discomfort, constipation, headache, rash, sleep disorder, palpitation, backache, and anorexia, occurred in 185 (22.34%) patients, with dizziness being the most common (75/828, 9.06%). Compliance with MCQT therapy was an independent factor influencing H. pylori eradication in patients receiving MCQT as a primary therapy. Compliance and presence or absence of H. pylori infection symptoms at the time of screening were independent factors influencing H. Pylori eradication in patients receiving MCQT as rescue therapy. Factors that influenced the occurrence of adverse events included reasons for H. pylori infection screening, residence, treatment compliance, and the use of acid-suppressant regimens.

Conclusion

MCQT regimens were effective in H. pylori infection eradication, and the treatment resulted only in fewer adverse events when used as primary or rescue therapies for H. pylori infection treatment. Future prospective studies with larger sample sizes and more comprehensive data are needed to validate our findings.

Antifungal Activity of Minocycline and Azoles Against Fluconazole-Resistant Candida Species

Candida species are the most common fungal pathogens to infect humans, and can cause life-threatening illnesses in individuals with compromised immune systems. Fluconazole (FLU) is the most frequently administered antifungal drug, but its therapeutic efficacy has been limited by the emergence of drug-resistant strains. When co-administered with minocycline (MIN), FLU can synergistically treat clinical Candida albicans isolates in vitro and in vivo. However, there have been few reports regarding the synergistic efficacy of MIN and azoles when used to treat FLU-resistant Candida species, including Candida auris. Herein, we conducted a microdilution assay wherein we found that MIN and posaconazole (POS) showed the best in vitro synergy effect, functioning against 94% (29/31) of tested strains, whereas combinations of MIN+itraconazole (ITC), MIN+voriconazole (VOR), and MIN+VOR exhibited synergistic activity against 84 (26/31), 65 (20/31), and 45% (14/31) of tested strains, respectively. No antagonistic activity was observed for any of these combinations. In vivo experiments were conducted in Galleria mellonella, revealing that combination treatment with MIN and azoles improved survival rates of larvae infected with FLU-resistant Candida. Together, these results highlight MIN as a promising synergistic compound that can be used to improve the efficacy of azoles in the treatment of FLU-resistant Candida infections.

Alternative treatment of fungal infections: Synergy with non-antifungal agents

Fungal infections are responsible for high mortality rates in immunocompromised and high-risk surgical patients. Therapy failures during the last decades due to increasing multidrug resistance demand innovative strategies for novel and effective antifungal drugs. Synergistic combinations of antifungals with non-antifungal agents highlight a pragmatic strategy to reduce the development of drug resistance and potentially repurpose known compounds with other functions to bypass costly and time-consuming novel drug development.

In Vitro and In Vivo Study on the Synergistic Effect of Minocycline and Azoles against Pathogenic Fungi

In vitro and in vivo interactions of minocycline and azoles, including itraconazole, voriconazole, and posaconazole, against filamentous pathogenic fungi were investigated. A total of 56 clinical isolates were studied in vitro via broth microdilution checkerboard technique, including 20 strains of Aspergillus fumigatus, 7 strains of Aspergillus flavus, 16 strains of Exophiala dermatitidis, 10 strains of Fusarium solani, and 3 strain s of Fusarium oxysporum The results revealed that minocycline did not exhibit any significant antifungal activity against any of the tested strains. However, favorable synergy of minocycline with itraconazole, voriconazole, or posaconazole was observed against 34 (61%), 28 (50%), and 38 (68%) isolates, respectively, including azole-resistant A. fumigatus and Fusarium spp. with inherently high MICs of azoles. Synergistic combinations resulted in 4-fold to 16-fold reduction of effective MICs of minocycline and azoles. No antagonism was observed. In vivo effects of minocycline-azole combinations were evaluated by survival assay in a Galleria mellonella model infected with E. dermatitidis strain BMU00034; F. solani strain FS9; and A. fumigatus strains AF293, AFR1, and AFR2. Minocycline acted synergistically with azoles and significantly increased larvae survival in all isolates (P < 0.001), including azole-resistant A. fumigatus and azole-inactive Fusarium spp. In conclusion, the results suggested that minocycline combined with azoles may help to enhance the antifungal susceptibilities of azoles against pathogenic fungi and had the potential to overcome azole resistance issues.

Vulvovaginitis Caused by Candida Species Following Antibiotic Exposure

PURPOSE OF REVIEW

Goal was to review epidemiology, pathophysiology, and prevention of post-antibiotic Candida vulvovaginitis (VVC).

RECENT FINDINGS

Antibacterial therapy, whether systemic or locally applied to the vagina, represents the single most frequent and predictable cause or triggering mechanism of symptomatic vulvovaginal candidiasis (VVC). Such initiating mechanisms may precipitate sporadic or recurrent episodes of VVC. In spite of this widely recognized association, the exact mechanism whereby antibiotics of all classes cause acute exacerbation of symptomatic vaginal disease remains largely unstudied and therefore largely unknown. Pathophysiology is hypothesized to be reduction or alteration of vaginal microbiome restraints of yeast colonization, proliferation, and expression of virulence characteristics. The predictable link between antibiotic use and post-antibiotic VVC affords practitioners an opportunity for timely intervention using selective, convenient antimycotics usually drugs but possibly probiotic measures. Indications and limitation of these steps are discussed.

TETX: a novel nuclear selection marker for Chlamydomonas reinhardtii transformation

BACKGROUND

Transformation of microalgae to obtain recombinant proteins, lipids or metabolites of economic value is of growing interest due to low costs associated with culture growth and scaling up. At present there are only three stable nuclear selection markers for the transformation of Chlamydomonas reinhardtii, which is the most commonly transformed microalgae, specifically: the aminoglycoside phosphotransferaseses aph7and aphVIII and the phleomycin resistance ble gene. As several microalgae are resistant to some of the antibiotics associated with the mentioned resistance genes, we have developed another alternative, tetX, a NADP-requiring Oxidoreductase that hydroxylates tetracycline substrates. We provide evidence that tetX can be used to obtain nuclear transformants of Chlamydomonas reinhardtii.

RESULTS

We obtained nuclear transformants harbouring the tetX gene under the control of beta 2 tubulin or HSP70ARBCS2 promoters at an efficiency of transformation of 3.28 and 6.18 colony forming units/μg DNA respectively. This is the first report of a eukaryotic cell transformed using tetracycline as a selectable marker.

CONCLUSIONS

We developed a protocol for the nuclear transformation of Chlamydomonas reinhardtii using tetX as a selectable marker that confers stable resistance to tetracycline up to 100 μg/mL. We believe tetX can be used to transform Chlamydomonas reinhardtii chloroplasts, related microalgae and other aerobic organisms sensitive to any tetracycline antibiotic.

Antibacterial therapeutics for the treatment of chytrid infection in amphibians: Columbus's egg?

BACKGROUND

The establishment of safe and effective protocols to treat chytridiomycosis in amphibians is urgently required. In this study, the usefulness of antibacterial agents to clear chytridiomycosis from infected amphibians was evaluated.

RESULTS

Florfenicol, sulfamethoxazole, sulfadiazine and the combination of trimethoprim and sulfonamides were active in vitro against cultures of five Batrachochytrium dendrobatidis strains containing sporangia and zoospores, with minimum inhibitory concentrations (MIC) of 0.5-1.0 μg/ml for florfenicol and 8.0 μg/ml for the sulfonamides. Trimethoprim was not capable of inhibiting growth but, combined with sulfonamides, reduced the time to visible growth inhibition by the sulfonamides. Growth inhibition of B. dendrobatidis was not observed after exposure to clindamycin, doxycycline, enrofloxacin, paromomycin, polymyxin E and tylosin. Cultures of sporangia and zoospores of B. dendrobatidis strains JEL423 and IA042 were killed completely after 14 days of exposure to 100 μg/ml florfenicol or 16 μg/ml trimethoprim combined with 80 μg/ml sulfadiazine. These concentrations were, however, not capable of efficiently killing zoospores within 4 days after exposure as assessed using flow cytometry. Florfenicol concentrations remained stable in a bathing solution during a ten day period. Exposure of Discoglossus scovazzi tadpoles for ten days to 100 μg/ml but not to 10 μg florfenicol /ml water resulted in toxicity. In an in vivo trial, post metamorphic Alytes muletensis, experimentally inoculated with B. dendrobatidis, were treated topically with a solution containing 10 μg/ml of florfenicol during 14 days. Although a significant reduction of the B. dendrobatidis load was obtained, none of the treated animals cleared the infection.

CONCLUSIONS

We thus conclude that, despite marked anti B. dendrobatidis activity in vitro, the florfenicol treatment used is not capable of eliminating B. dendrobatidis infections from amphibians.

The combination of minocycline and fluconazole causes synergistic growth inhibition against Candida albicans: an in vitro interaction of antifungal and antibacterial agents

Combination therapy can be used for the treatment of fungal infections, especially for those caused by antifungal-resistant fungi. In the present study, in vitro interactions and mechanisms between fluconazole and minocycline against Candida albicans were evaluated. The nature of the interactions determined by spectrophotometric method in a checkerboard assay was interpreted using nonparametric models of fractional inhibitory concentration index (FICI) and percentages of growth difference (ΔE). In the mechanism study, we evaluated the potential activity of minocycline on fluconazole penetrating the C. albicans biofilm. Furthermore, the effect of fluconazole and minocycline alone and in combination on the cellular calcium balance, as well as on the uptake and efflux of fluconazole were evaluated. It was found that fluconazole can work synergistically with minocycline against fluconazole-resistant C. albicans; the minimum inhibitory concentration of fluconazole decreased from 512 to 2 microgmL(-1) when fluconazole and minocycline were given in combination, with an FICI of 0.035 and 0.064 and high-percentage synergistic interactions of 1250% and 988% for the two resistant strains. The mechanism of action was suggested to be the enhancement of minocycline on fluconazole penetrating biofilm, and inducing the intracellular calcium release, instead of impacting on the uptake and efflux of fluconazole. Our results suggest that the combination of fluconazole and minocycline can reduce the fluconazole resistance of C. albicans in vitro.

In vitro minocycline activity on superinfecting microorganisms isolated from chronic periodontitis patients

Chronic periodontitis is the most common type of periodontitis and it is associated with various species of microorganisms. Enteric rods, Pseudomonas, Staphyloccocus and Candida have been retrieved from periodontal pockets of patients with chronic periodontitis and correlated to cases of superinfection. Local or systemic antibiotic therapy is indicated to reinforce the effects of the conventional mechanical therapy. Minocycline has been suggested as one of the most effective drugs against periodontal pathogens. The aim of this work was to evaluate the minimal inhibitory concentration (MIC) of minocycline on superinfecting microorganisms isolated from the periodontal pocket and the oral cavity of individuals with chronic periodontitis. Isolates of Enterobacteriaceae (n = 25), Staphylococcus spp. (n = 25), Pseudomonas aeruginosa (n = 9) and Candida spp. (n = 25) were included in the study. Minimal inhibitory concentrations (MIC) of minocycline were determined using the Müeller-Hinton agar dilution method. Staphylococcus spp. isolates were the most sensitive to minocycline with a MIC of 8 µg/mL, followed by Enterobacteriaceae with a MIC of 16 µg/mL. The concentration of 16 µg/mL inhibited 96% of Candida spp. isolates. The MIC for 88.8% of the isolates of Pseudomonas aeruginosa was 128 µg/mL. A concentration of 1,000 µg/mL was not enough to inhibit 100% of the tested isolates.

Antibiotic-associated vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is one of the most common causes of vaginitis, and its incidence has increased markedly during the past three decades. The widespread overuse of antibiotics has been suggested as one of the major factors contributing to the increasing incidence of VVC. However, evidence supporting this association has been limited because few studies with rigorous scientific methodology have been conducted. Moreover, existing data regarding the risk for developing VVC after antibiotic use are conflicting. This review examines the available information in the literature regarding antibiotic-associated VVC, its incidence, and its potential mechanisms. Implications for clinical practice and research are also discussed.

Antibiotics and prevention of microbial colonization of catheters

Slime-producing staphylococci frequently colonize catheters, and when they are embedded in biofilm, they become resistant to various antibiotics. In the study that is described, the comparative efficacies of vancomycin, clindamycin, novobiocin, and minocycline, alone or in combination with rifampin, were tested in an in vitro model of colonization. The model consisted of the modified Robbins device with antibiotic-impregnated cement filling the lumen of catheter segments. The synergistic combination of minocycline and rifampin was the most efficacious in preventing bacterial colonization of slime-producing strains of Staphylococcus epidermidis and Staphylococcus aureus to catheter surfaces. A similar trend was observed when the inhibitory activities of polyurethane catheters coated with minocycline and rifampin were compared with the inhibitory activities of catheters coated with other antimicrobial agents. The inhibitory activities of catheters coated with minocycline and rifampin against S. epidermidis, S. aureus, and Enterococcus faecalis strains, for example, were significantly better than those of catheters coated with vancomycin (P < 0.05). The inhibitory activities of catheters coated with minocycline and rifampin against gram-negative bacilli and Candida albicans were comparable to those of catheters coated with ceftazidime and amphotericin B, respectively. We found that the combination of minocycline and rifampin is unique and highly effective in preventing the colonization of catheters with slime-producing staphylococci and that it also displays a broad-spectrum inhibitory activity against gram-negative bacteria and yeast cells.

Effects of minocycline and tetracycline on the vaginal yeast flora

Two groups of women with non-specific genital infection were treated for two weeks with tetracycline 250 mg six-hourly and minocycline 100 mg twice daily respectively. Cultures for yeasts were performed before treatment and at the end of the first and second weeks. Before treatment yeasts, mostly Candida albicans, were recovered from 13% of the women. After one and two weeks' treatment yeasts were isolated from 22 and 29% of women treated with tetracycline, and from 19 and 29% of women treated with minocycline. It is concluded that despite inhibition of the growth of yeasts shown by minocycline in vitro, there is no evidence of any significant difference between the actions of tetracycline and minocycline on the vaginal yeast flora.

Minocycline: A review of its antibacterial and pharmacokinetic properties and therapeutic use

Minocycline is a semi-synthetic tetracycline derivative which is well absorbed and distributed in body tissues and is suitable for twice daily administration. It appears to be as generally effective as other tetracyclines and analogues, but also to be effective in infections due to tetracycline-resistant staphylococci. Side-effects are typical of those of other tetracyclines, but minocycline has been associated with a high incidence of vertigo in some studies. On the other hand, minocycline appears to have little or no photosensitising potential. It is not yet clear whether minocycline can be safely used in patients with moderate or severe impairment of renal function, but if used in renal failure, the plasma urea concentration should be monitored.