45 years of tetracycline post exposure prophylaxis for STIs and the risk of tetracycline resistance: a systematic review and meta-analysis.

There is considerable interest in the use of doxycycline post exposure prophylaxis (PEP) to reduce the incidence of bacterial sexually transmitted infections (STIs). An important concern is that this could select for tetracycline resistance in these STIs and other species. We searched PubMed and Google Scholar, (1948-2023) for randomized controlled trials comparing tetracycline PEP with non-tetracycline controls. The primary outcome was antimicrobial resistance (AMR) to tetracyclines in all bacterial species with available data. Our search yielded 140 studies, of which three met the inclusion criteria. Tetracycline PEP was associated with an increasedprevalence of tetracycline resistance in Neisseria gonorrhoeae, but this effect was not statistically significant (Pooled OR 2.3, 95% CI 0.9-3.4). PEP had a marked effect on the N. gonorrhoeae tetracycline MIC distribution in the one study where this was assessed. Prophylactic efficacy was 100% at low MICs and 0% at high MICs. In the one study where this was assessed, PEP resulted in a significant increase in tetracycline resistance in commensal Neisseria species compared to the control group (OR 2.9, 95% CI 1.5-5.5) but no significant effect on the prevalence of tetracycline resistance in Staphylococcus aureus. The available evidence suggests that PEP with tetracyclines could be associated with selecting tetracycline resistance in N. gonorrhoeae and commensal Neisseria species.

State-transition modeling of blood transcriptome predicts disease evolution and treatment response in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is initiated and maintained by BCR::ABL which is clinically targeted using tyrosine kinase inhibitors (TKIs). TKIs can induce long-term remission but are also not curative. Thus, CML is an ideal system to test our hypothesis that transcriptome-based state-transition models accurately predict cancer evolution and treatment response. We collected time-sequential blood samples from tetracycline-off (Tet-Off) BCR::ABL-inducible transgenic mice and wild-type controls. From the transcriptome, we constructed a CML state-space and a three-well leukemogenic potential landscape. The potential's stable critical points defined observable disease states. Early states were characterized by anti-CML genes opposing leukemia; late states were characterized by pro-CML genes. Genes with expression patterns shaped similarly to the potential landscape were identified as drivers of disease transition. Re-introduction of tetracycline to silence the BCR::ABL gene returned diseased mice transcriptomes to a near healthy state, without reaching it, suggesting parts of the transition are irreversible. TKI only reverted the transcriptome to an intermediate disease state, without approaching a state of health; disease relapse occurred soon after treatment. Using only the earliest time-point as initial conditions, our state-transition models accurately predicted both disease progression and treatment response, supporting this as a potentially valuable approach to time clinical intervention, before phenotypic changes become detectable.

Efficacies of three drug regimens containing omadacycline to treat Mycobacteroides abscessus disease.

Mycobacteroides abscessus (Mab, also known as Mycobacterium abscessus) causes opportunistic pulmonary and soft tissue infections that are difficult to cure with existing treatments. Omadacycline, a new tetracycline antibiotic, exhibits potent in vitro and in vivo activity against Mab. As regimens containing multiple antibiotics are required to produce a durable cure for Mab disease, we assessed efficacies of three three-drug combinations in a pre-clinical mouse model of pulmonary Mab disease to identify companion drugs with which omadacycline exhibits the highest efficacy. Additionally, we assessed the susceptibility of Mab recovered from mouse lungs after four weeks of exposure to the three triple-drug regimens. Among the three-drug regimens, omadacycline + imipenem + amikacin produced the largest reduction in Mab burden, whereas omadacycline + imipenem + linezolid exhibited the most effective early bactericidal activity. Omadacycline + linezolid + clofazimine, a regimen that can be administered orally, lacked early bactericidal activity but produced a gradual reduction in the lung Mab burden over time. The robust efficacy exhibited by these three regimens in the mouse model supports their further evaluation in patients with Mab lung disease. As we were unable to isolate drug-resistant Mab mutants at the completion of four weeks of treatment, these triple-drug combinations show promise of producing durable cure and minimizing selection of resistant mutants.

Systematic Review: Clinical Features, Antimicrobial Treatment, and Outcomes of Human Tularemia, 1993-2023.

BACKGROUND: Francisella tularensis, the causative agent of tularemia, is endemic throughout the Northern Hemisphere and requires as few as 10 organisms to cause disease, making this potential bioterrorism agent one of the most infectious bacterial pathogens known. Aminoglycosides, tetracyclines, and, more recently, fluoroquinolones are used for treatment of tularemia; however, data on the relative effectiveness of these and other antimicrobial classes are limited. METHODS: Nine databases, including Medline, Global Health, and Embase, were systematically searched for articles containing terms related to tularemia. Articles with case-level data on tularemia diagnosis, antimicrobial treatment, and patient outcome were included. Patient demographics, clinical findings, antimicrobial administration, and outcome (eg, intubation, fatality) were abstracted using a standardized form. RESULTS: Of the 8878 publications identified and screened, 410 articles describing 870 cases from 1993 to 2023 met inclusion criteria. Cases were reported from 35 countries; more than half were from the United States, Turkey, or Spain. The most common clinical forms were ulceroglandular, oropharyngeal, glandular, and pneumonic disease. Among patients treated with aminoglycosides (n = 452 [52%]), fluoroquinolones (n = 339 [39%]), or tetracyclines (n = 419 [48%]), the fatality rate was 0.7%, 0.9%, and 1.2%, respectively. Patients with pneumonic disease who received ciprofloxacin had no fatalities and the lowest rates of thoracentesis/pleural effusion drainage and intubation compared to those who received aminoglycosides and tetracyclines. CONCLUSIONS: Aminoglycosides, fluoroquinolones, and tetracyclines are effective antimicrobials for treatment of tularemia, regardless of clinical manifestation. For pneumonic disease specifically, ciprofloxacin may have slight advantages compared to other antimicrobials.

Tularemia Clinical Manifestations, Antimicrobial Treatment, and Outcomes: An Analysis of US Surveillance Data, 2006-2021.

BACKGROUND: Tularemia, a potentially fatal zoonosis caused by Francisella tularensis, has been reported from nearly all US states. Information on relative effectiveness of various antimicrobials for treatment of tularemia is limited, particularly for newer classes such as fluoroquinolones. METHODS: Data on clinical manifestations, antimicrobial treatment, and illness outcome of patients with tularemia are provided voluntarily through case report forms to the US Centers for Disease Control and Prevention by state and local health departments. We summarized available demographic and clinical information submitted during 2006-2021 and evaluated survival according to antimicrobial treatment. We grouped administered antimicrobials into those considered effective for treatment of tularemia (aminoglycosides, fluoroquinolones, and tetracyclines) and those with limited efficacy. Logistic regression models with a bias-reduced estimation method were used to evaluate associations between antimicrobial treatment and survival. RESULTS: Case report forms were available for 1163 US patients with tularemia. Francisella tularensis was cultured from a clinical specimen (eg, blood, pleural fluid) in approximately half of patients (592; 50.9%). Nearly three-quarters (853; 73.3%) of patients were treated with a high-efficacy antimicrobial. A total of 27 patients (2.3%) died. After controlling for positive culture as a proxy for illness severity, use of aminoglycosides, fluoroquinolones, and tetracyclines was independently associated with increased odds of survival. CONCLUSIONS: Most US patients with tularemia received high-efficacy antimicrobials; their use was associated with improved odds of survival regardless of antimicrobial class. Our findings provide supportive evidence that fluoroquinolones are an effective option for treatment of tularemia.

Fecal Pharmacokinetics and Gut Microbiome Effects of Oral Omadacycline Versus Vancomycin in Healthy Volunteers.

BACKGROUND: Clostridioides difficile infection (CDI) is a common healthcare-associated infection with limited treatment options. Omadacycline, an aminomethylcycline tetracycline, has potent in vitro activity against C difficile and a low propensity to cause CDI in clinical trials. We aimed to assess fecal pharmacokinetics and gut microbiome effects of oral omadacycline compared to oral vancomycin in healthy adults. METHODS: This was a phase 1, nonblinded, randomized clinical trial conducted in healthy volunteers aged 18-40 years. Subjects received a 10-day course of omadacycline or vancomycin. Stool samples were collected at baseline, daily during therapy, and at follow-up visits. Omadacycline and vancomycin stool concentrations were assessed, and microbiome changes were compared. RESULTS: Sixteen healthy volunteers with a mean age of 26 (standard deviation [SD], 5) years were enrolled; 62.5% were male, and participants' mean body mass index was 23.5 (SD, 4.0) kg/m2. Omadacycline was well tolerated with no safety signal differences between the 2 antibiotics. A rapid initial increase in fecal concentrations of omadacycline was observed compared to vancomycin, with maximum concentrations achieved within 48 hours. A significant difference in alpha diversity was observed following therapy in both the omadacycline and vancomycin groups (P < .05). Bacterial abundance and beta diversity analysis showed differing microbiome changes in subjects who received omadacycline versus vancomycin. CONCLUSIONS: Subjects given omadacycline had high fecal concentrations with a distinct microbiome profile compared to vancomycin. CLINICAL TRIALS REGISTRATION: NCT06030219.

Pharmacokinetic and pharmacodynamic evaluation of the atypical tetracyclines chelocardin and amidochelocardin in murine infection models.

IMPORTANCE: There is a strong need to find novel treatment options against urinary tract infections associated with antimicrobial resistance. This study evaluates two atypical tetracyclines, namely chelocardin (CHD) and amidochelocardin (CDCHD), with respect to their pharmacokinetics and pharmacodynamics. We show CHD and CDCHD are cleared at high concentrations in mouse urine. Especially, CDCHD is highly effective in an ascending urinary tract infection model, suggesting further preclinical evaluation.

Eravacycline, the first four years: health outcomes and tolerability data for 19 hospitals in 5 U.S. regions from 2018 to 2022.

IMPORTANCE: The rise of multidrug-resistant (MDR) pathogens, especially MDR Gram-negatives, poses a significant challenge to clinicians and public health. These resilient bacteria have rendered many traditional antibiotics ineffective, underscoring the urgency for innovative therapeutic solutions. Eravacycline, a broad-spectrum fluorocycline tetracycline antibiotic approved by the FDA in 2018, emerges as a promising candidate, exhibiting potential against a diverse array of MDR bacteria, including Gram-negative, Gram-positive, anaerobic strains, and Mycobacterium. However, comprehensive data on its real-world application remain scarce. This retrospective cohort study, one of the largest of its kind, delves into the utilization of eravacycline across various infectious conditions in the USA during its initial 4 years post-FDA approval. Through assessing clinical, microbiological, and tolerability outcomes, the research offers pivotal insights into eravacycline's efficacy in addressing the pressing global challenge of MDR bacterial infections.

The combination of tetracyclines effectively ameliorates liver fibrosis via inhibition of EphB1/2.

Eph receptor tyrosine kinase EphB1/2 contributes to the development of liver fibrosis, suggesting the rationale that EphB1/2 inhibitors may be effective in liver fibrosis therapy. Since tetracycline antibiotics were recently demonstrated as EphB kinase inhibitors, in present study we investigated their therapeutic potential against liver fibrosis. Our results showed that the tetracycline combination of demeclocycline (D), chlortetracycline (C), and minocycline (M) inhibited the activation of hepatic stellate cells (HSCs) in vitro and alleviated CCl4-induced animal model of liver fibrosis in vivo. Mechanistically, DCM combination inhibited EphB1/2 phosphorylation and subsequent activation of the MAPK signaling. Moreover, we found that short-term and low-dose DCM combination treatment decreased tissue inflammation and improved liver fibrosis in mice. Thus, our study indicates that tetracyclines may be repurposed for the treatment of liver fibrosis.

Pharmacological Management of Cholera: A Century of Expert Opinions in Cecil Textbook of Medicine.

BACKGROUND: Cholera is a potentially lethal diarrheal disease produced by Vibrio cholerae serotypes O1 El Tor and O139. Known since antiquity, the condition causes epidemics in many areas, particularly in Asia, Africa, and South America. Left untreated, the mortality may reach 50%. The crucial therapeutic intervention is intravenous or oral rehydration and correction of acidosis, dyselectrolytemia, and renal impairment. Antibiotic use represents the main pharmacological intervention. STUDY QUESTION: What are the milestones of the antibiotics use recommended by experts for the pharmacological management of cholera in the past century? STUDY DESIGN: To determine the changes in the experts' approach to the management of cholera and particularly the use of antibiotics as presented in a widely used textbook in the United States. DATA SOURCES: The chapters describing the management of cholera in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020. RESULTS: Sulfonamides were recommended in 1947, followed by the introduction of tetracyclines, chloramphenicol, and furazolidone in 1955. The options were restricted in 2000 to doxycycline. In the past decade, patients infected with strains known to have a degree a resistance to tetracyclines were treated with azithromycin or ciprofloxacin. Antibiotic use decreases the volume of stool and the duration of diarrhea but has not been considered lifesaving. Drugs with antimotility, antiemetic, or antisecretory properties are not useful. CONCLUSIONS: The utility of antibiotic use in cholera has been endorsed by experts, but only as an adjunct to rapid and complete fluid and electrolyte replacement.

Case Report: Omadacycline in the treatment of macrolide-unresponsive Mycoplasma pneumoniae pneumonia in an adolescent patient.

Omadacycline is a novel tetracycline antibiotic that exhibits good in vitro antibacterial activity against atypical pathogens such as Mycoplasma pneumoniae. It is approved for the treatment of adults with community-acquired bacterial pneumonia. However, the safety and efficacy of omadacycline in pediatric patients under 18 years of age have not yet been established. In the present paper, we report a case of pediatric community-acquired pneumonia in which initial empirical anti-infective therapy had failed. The patient received empirical anti-infective therapy with azithromycin and other antimicrobial agents upon admission but showed a poor clinical response and developed secondary tinnitus and liver dysfunction. After the confirmation of M. pneumoniae infection through metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid, an antibiotic switch to omadacycline was made. Thereafter, the patient's condition improved, and no adverse reactions were observed. These findings demonstrate that mNGS enables the identification of infection-causing pathogens in patients with unresponsive pneumonia. Omadacycline can be considered as an alternative option for anti-infective therapy in pediatric M. pneumoniae pneumonia, especially when the presence of bacterial resistance, adverse drug reactions, or organ failure are taken into consideration.

The pharmacokinetic evaluation of omadacycline (Oral Only Dosing Regimen) for the treatment of Community-Acquired Bacterial Pneumonia (CABP).

INTRODUCTION: Omadacycline is a new analog of the tetracycline class active against atypical bacteria, as well as against staphylococci, including methicillin-resistant strains, and Streptococcus pneumoniae. AREAS COVERED: This review has summarized the available clinical evidence on the use of oral omadacycline in the treatment of community-acquired pneumonia (CAP) and described the mechanism of action, pharmacokinetic/pharmacodynamic (PK/PD) parameters in healthy and special populations and the latest research on omadacycline. EXPERT OPINION: The available clinical evidence on oral omadacycline for the treatment of CAP shows that its properties provide reliable empirical coverage for pathogens such as Haemophilus influenzae, Moraxella catarrhalis, and species of Legionella, Chlamydia, and Mycoplasma. Omadacycline is also active against methicillin-resistant Staphylococcus aureus (MRSA); penicillin-resistant and multidrug-resistant Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae; and vancomycin-resistant Enterococcus spp. A dose of 450 mg orally once daily is recommended, followed by a maintenance dose of 300 mg orally once daily. Importantly, omadacycline does not require dose adjustment for patients based on BMI, age, gender, or renal or hepatic impairment.

Clinical Effectiveness of Tetracycline-Class Agents Based Regimens in Patients With Carbapenem-Resistant Acinetobacter baumannii Bacteremia: A Single-Center Retrospective Cohort Study.

This study evaluated the clinical outcome of carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia and the clinical effectiveness of tetracyclines-based therapy. In a retrospective cohort study over 5 years period, 108 patients were included in the study. The overall 30-day mortality rate was 71.4%. Pitt's bacteremia score (PBS) (adjusted hazard ratio [aHR], 1.32; 95% confidence interval [CI], 1.22-1.42 per 1-point), colistin-single regimens (aHR, 0.34; 95% CI, 0.17-0.69), and tetracyclines single/tetracyclines-colistin combination regimens (aHR, 0.18; 95% CI, 0.07-0.48) were independently associated with 30-day mortality. Among patients with a PBS < 6, only tetracycline-containing regimens were associated with decreased mortality. Among patients receiving appropriate definite antimicrobials, the tetracyclines-colistin combination (7 of 7, 100%) tended to a higher 30-day survival rate compared to a tetracycline (7 of 12, 57.1%) or colistin single regimen (10 of 22, 41.6%, P = 0.073). Our findings suggest tetracyclines might be effective for treating CRAB infections when combined with colistin.

Rosacea in children: a review.

Rosacea is a facial inflammatory disorder that shows an increasing incidence with age. While rosacea is common > 60 years of age, pediatric rosacea is uncommon. Diagnostic criteria are based on clinical symptoms. Laboratory investigations and histopathology are only needed to exclude other differential diagnoses. There are several subtypes such as erythemato-telangiectatic, papulo-pustular, periorificial, and granulomatous variants. In contrast to adult rosacea, phymatous subtypes do not belong to pediatric rosacea. A special subtype seen in infants and children is an idiopathic facial aseptic granuloma. Genetic and environmental factors contribute to its pathogenesis. Treatment options are in analogy to adult rosacea classified into topical and systemic drugs. In the case of oral tetracyclines, discoloration of teeth and impairment of enamel are possible adverse events. CONCLUSION: Pediatric rosacea belongs to the rosacea spectrum but has peculiarities compared to the adult subtype. WHAT IS KNOWN: • Rosacea is a chronic inflammatory disorder different from acne. • Rosacea gets more common with advanced age. WHAT IS NEW: • Pediatric rosacea is an uncommon subtype with peculiar clinical presentation. • Demodicosis is very rare in immunocompetent children.

[Multidisciplinary expert consensus on the rational use of tetracyclines commonly used in clinical practice].

In recent years, the emergence of newly detected pathogens and the increase of drug resistant bacterial bring serious challenges for the diagnosis and treatment of infectious diseases. Tetracycline drugs are widely used in clinical practice, and the varieties of these drugs are constantly being updated. However, there is still a lack of guidance documents for the rational clinical application of tetracycline drugs in China. Meanwhile, some healthcare workers have doubts about their pharmaceutical characteristics, timing and methods of clinical application. In order to further standardize the clinical application of tetracycline drugs and provide professional evidence-based medicine suggestions for medical personnel in medical institutions, under the leadership of Hospital Infection Control Branch of Chinese Preventive Medicine Association and Clinical Pharmacology Branch of Chinese Pharmacological Society, experts from areas of infection, respiratory medicine, critical care medicine, emergency, infection control, pharmacy and other disciplines organized a consensus meeting and formulated multidisciplinary expert consensus on the rational use of tetracyclines commonly used in clinical practice. This expert consensus is based on the pharmaceutical characteristics of tetracyclines commonly used in China, the mechanism of action and drug resistance status of tetracyclines, combined with the infection site, pathogen characteristics and bacterial drug resistance. This expert consensus also pays attention to special populations and off-label drug use, and integrates domestic and foreign recommendations and the latest evidence-based medicine evidence, and 17 expert consensus opinions for clinical physicians, pharmacists, and other professionals in medical institutions to refer to were formed. In view of the particularity and complexity of infectious diseases and the individual differences of patients, in order to benefit patients, individualized anti-infection strategies should be implemented.

In Vitro Synergistic Effects of Omadacycline with Other Antimicrobial Agents against Mycobacterium abscessus.

The clinical importance of Mycobacterium abscessus species (MABS) infections has been increasing. However, the standard treatment regimens recommended in the current guidelines often result in unfavorable outcomes. Therefore, we investigated the in vitro activity of omadacycline (OMC), a novel tetracycline, against MABS to explore its potential as a novel therapeutic option. The drug susceptibilities of 40 Mycobacterium abscessus subsp. abscessus (Mab) clinical strains obtained from the sputum of 40 patients from January 2005 to May 2014 were investigated. The MIC results for OMC, amikacin (AMK), clarithromycin (CLR), clofazimine (CLO), imipenem (IPM), rifabutin (RFB), and tedizolid (TZD) alone and their combined effects (with OMC) were examined using the checkerboard method. Additionally, we studied the differences in the effectiveness of the antibiotic combinations based on the colony morphotype of Mab. The MIC50 and MIC90 of OMC alone were 2 and 4 µg/mL, respectively. The combinations of OMC with AMK, CLR, CLO, IPM, RFB, and TZD showed synergy against 17.5%, 75.8%, 25.0%, 21.1%, 76.9%, and 34.4% of the strains, respectively. Additionally, OMC combined with CLO (47.1% versus 9.5%, P = 0.023) or TZD (60.0% versus 12.5%, P = 0.009) showed significantly higher synergy against strains with rough morphotypes than those with smooth morphotypes. In conclusion, the checkerboard analyses revealed that the synergistic effects of OMC were observed most frequently with RFB, followed by CLR, TZD, CLO, IPM, and AMK. Furthermore, OMC tended to be more effective against rough-morphotype Mab strains.

Omadacycline pharmacokinetics/pharmacodynamics in the hollow fiber model and clinical validation of efficacy to treat pulmonary Mycobacterium abscessus disease.

BACKGROUND: Guideline-based therapy (GBT) for pulmonary Mycobacterium abscessus (Mab) disease achieves sustained sputum culture conversion (SSCC) rates of 30%; this is reflected by poor efficacy of GBT in the hollow fiber system model of Mab (HFS-Mab), which killed ∼1.22 log10 CFU/mL. This study was performed to determine which clinical dose of omadacycline, a tetracycline antibiotic, should be used in combination therapy to treat pulmonary Mab disease for relapse-free cure. METHODS: First, omadacycline intrapulmonary concentration-time profiles of seven daily doses were mimicked in the HFS-Mab model and exposures associated with optimal efficacy were identified. Second, 10,000 subject Monte-Carlo simulations were performed to determine whether oral omadacycline 300 mg/day achieved these optimal exposures. Third, a retrospective clinical study on omadacycline vs. primarily tigecycline-based salvage therapy was conducted to assess rates of SSCC and toxicity. Fourth, a single patient was recruited to validate the findings. RESULTS: Omadacycline efficacy in the HFS-Mab was 2.09 log10 CFU/mL at exposures achieved in >99% of patients on 300 mg/day omadacycline. In the retrospective study of omadacycline 300 mg/day-based combinations vs. comparators, SSCC was achieved in 8/10 vs. 1/9 (P=0.006), symptom improvement in 8/8 vs. 5/9 (P=0.033), toxicity in 0 vs. 9/9 (P<0.001), and therapy discontinuation due to toxicity in 0 vs. 3/9 (P<0.001) cases, respectively. In one prospectively recruited patient, omadacycline 300 mg/day salvage therapy achieved SSCC and symptom-resolution in 3 months. CONCLUSION: Based on the preclinical and clinical data, omadacycline 300 mg/day in combination regimens could be appropriate for testing in Phase III trials in patients with Mab pulmonary disease.

Collateral sensitivity between tetracyclines and aminoglycosides constrains resistance evolution in carbapenem-resistant Klebsiella pneumoniae.

AIMS: The acquisition of resistance to one antibiotic may confer an increased sensitivity to another antibiotic in bacteria, which is an evolutionary trade-off between different resistance mechanisms, defined as collateral sensitivity (CS). Exploiting the role of CS in treatment design could be an effective method to suppress or even reverse resistance evolution. METHODS: Using experimental evolution, we systematically studied the CS between aminoglycosides and tetracyclines in carbapenem-resistant Klebsiella pneumoniae (CRKP) and explored the underlying mechanisms through genomic and transcriptome analyses. The application of CS-based therapies for resistance suppression, including combination therapy and alternating antibiotic therapy, was further evaluated in vitro and in vivo. RESULTS: Reciprocal CS existed between tetracyclines and aminoglycosides in CRKP. The increased sensitivity of aminoglycoside-resistant strains to tetracyclines was associated with the alteration of bacterial membrane potential, whereas the unbalanced oxidation-reduction process of tetracycline-resistant strains may lead to an increased bacterial sensitivity to aminoglycosides. CS-based combination therapy could efficiently constrain the evolution of CRKP resistance in vitro and in vivo. In addition, alternating antibiotic therapy can re-sensitize CRKP to previously resistant drugs, thereby maintaining the trade-off. CONCLUSIONS: These results provide new insights into constraining the evolution of CRKP resistance through CS-based therapies.