Doxycycline and Tigecycline: Two Friendly Drugs with a Low Association with Clostridium Difficile Infection

Occurrence, fate, and risk assessment of typical tetracycline antibiotics in the aquatic environment: A review

Tetracyclines (TCs), used as human and veterinary medicines, are the most widely used antibiotics. More than 75% of TCs are excreted in an active form and released into the environment through human and animal urine and feces, causing adverse effects on the ecological system and human health. Few articles review the environmental occurrence and behaviors of TCs, as well as their risks and toxicities. Here, we comprehensively summarized the recent advances on the following important issues: (1) Environmental occurrence of TCs. TCs are used globally and their occurrence in the aquatic environment has been documented, including surface water, groundwater, drinking water, wastewater, sediment, and sludge. (2) Environmental behaviors of TCs, particularly the fate of TCs in wastewater treatment plants (WWTPs). Most WWTPs cannot effectively remove TCs from wastewater, so alternative methods for efficient removal of TCs need to be developed. The latest degradation methods of TCs are summarized, including adsorption, photocatalytic, photochemical and electrochemical, and biological degradations. (3) Toxicities and possible risks of TCs. The toxicological data of TCs indicate that several TCs are more toxic to algae than fish and daphnia. Risk assessments based on individual compound exposure indicate that the risks arising from the current concentrations of TCs in the aquatic environment cannot be ignored.

Doxycycline Malaria Prophylaxis Impact on Risk of Travelers' Diarrhea among International Travelers

International travelers are frequently at risk for travelers' diarrhea (TD) and malaria. Doxycycline was one of the earliest antibiotics shown to have efficacy in TD prevention. With increasing resistance and recommendations against antibiotic chemoprophylaxis, doxycycline fell out of use. We evaluated TD incidence and risk factors in a prospective cohort of travelers, specifically in regard to malaria prophylaxis. Travelers' diarrhea was defined as ≥ 3 loose stools in 24 hours or two loose stools in 24 hours associated with other gastrointestinal symptoms. The Poisson regression model with robust error variance was used to estimate the RR of TD. Three thousand two hundred twenty-seven trips were enrolled: 62.1% of participants were male, with a median age of 39 years (interquartile range [IQR] 27,59) and a median travel duration of 19 days (IQR 12,49); 17.4% developed TD; 32% traveled to Africa, 40% to Asia, and 27% to the Caribbean and Latin America; and 20% took doxycycline for malaria chemoprophylaxis, 50% took other antimalarials, and 30% took none. Decreased RR of TD was associated with doxycycline (RR 0.62 [0.47-0.82], P < 0.01) and military travel (RR 0.57 [0.47-0.70], P < 0.01). Increased risk of TD was associated with female gender (RR 1.28 [1.09-1.50], P < 0.01), hotel accommodations (RR 1.30 [1.10-1.53], P < 0.01), travel to tropical South America (RR 1.34 [1.09-1.64], P < 0.01), and duration of travel (RR 1.00 [1.00-1.01], P < 0.01). The use of doxycycline for malaria prophylaxis is associated with lower TD risk, suggesting increasing bacterial enteropathogen susceptibility similar to previous observations. Doxycycline selection for antimalarial chemoprophylaxis may provide additional traveler benefit in infection prevention.

Omadacycline for Acute Bacterial Skin and Skin-Structure Infections

BACKGROUND

Acute bacterial skin and skin-structure infections are associated with substantial morbidity and health care costs. Omadacycline, an aminomethylcycline antibiotic that can be administered once daily either orally or intravenously, is active against pathogens that commonly cause such infections, including antibiotic-resistant strains.

METHODS

In this double-blind trial, we randomly assigned adults with acute bacterial skin and skin-structure infections (in a 1:1 ratio) to receive omadacycline (100 mg given intravenously every 12 hours for two doses, then 100 mg given intravenously every 24 hours) or linezolid (600 mg given intravenously every 12 hours). A transition to oral omadacycline (300 mg every 24 hours) or oral linezolid (600 mg every 12 hours) was allowed after 3 days; the total treatment duration was 7 to 14 days. The primary end point was an early clinical response at 48 to 72 hours, defined as survival with a reduction in lesion size of at least 20% without rescue antibacterial therapy. A secondary end point was an investigator-assessed clinical response at the post-treatment evaluation 7 to 14 days after the last dose, with clinical response defined as survival with resolution or improvement in signs or symptoms of infection to the extent that further antibacterial therapy was unnecessary. For both end points, the noninferiority margin was 10 percentage points.

RESULTS

In the modified intention-to-treat population, omadacycline (316 patients) was noninferior to linezolid (311 patients) with respect to early clinical response (rate of response, 84.8% and 85.5%, respectively; difference, -0.7 percentage points; 95% confidence interval [CI], -6.3 to 4.9). Omadacycline also was noninferior to linezolid with respect to investigator-assessed clinical response at the post-treatment evaluation in the modified intention-to-treat population (rate of response, 86.1% and 83.6%, respectively; difference, 2.5 percentage points; 95% CI, -3.2 to 8.2) and in the clinical per-protocol population (96.3% and 93.5%, respectively; difference, 2.8 percentage points; 95% CI, -1.0 to 6.9). In both groups, the efficacy of the trial drug was similar for methicillin-susceptible and methicillin-resistant Staphylococcus aureus infections. Adverse events were reported in 48.3% of the patients in the omadacycline group and in 45.7% of those in the linezolid group; the most frequent adverse events in both groups were gastrointestinal (in 18.0% and 15.8% of the patients in the respective groups).

CONCLUSIONS

Omadacycline was noninferior to linezolid for the treatment of acute bacterial skin and skin-structure infections and had a similar safety profile. (Funded by Paratek Pharmaceuticals; OASIS-1 ClinicalTrials.gov number, NCT02378480 .).

Omadacycline for Community-Acquired Bacterial Pneumonia

BACKGROUND

Omadacycline, a new once-daily aminomethylcycline antibiotic agent that can be administered intravenously or orally, reaches high concentrations in pulmonary tissues and is active against common pathogens that cause community-acquired bacterial pneumonia.

METHODS

In a double-blind trial, we randomly assigned (in a 1:1 ratio) adults with community-acquired bacterial pneumonia (Pneumonia Severity Index risk class II, III, or IV) to receive omadacycline (100 mg intravenously every 12 hours for two doses, then 100 mg intravenously every 24 hours), or moxifloxacin (400 mg intravenously every 24 hours). A transition to oral omadacycline (300 mg every 24 hours) or moxifloxacin (400 mg every 24 hours), respectively, was allowed after 3 days; the total treatment duration was 7 to 14 days. The primary end point was early clinical response, defined as survival with improvement in at least two of four symptoms (cough, sputum production, pleuritic chest pain, and dyspnea) and no worsening of symptoms at 72 to 120 hours, without receipt of rescue antibacterial therapy. A secondary end point was investigator-assessed clinical response at a post-treatment evaluation 5 to 10 days after the last dose, with clinical response defined as resolution or improvement in signs or symptoms to the extent that further antibacterial therapy was unnecessary. A noninferiority margin of 10 percentage points was used.

RESULTS

The intention-to-treat population included 386 patients in the omadacycline group and 388 patients in the moxifloxacin group. Omadacycline was noninferior to moxifloxacin for early clinical response (81.1% and 82.7%, respectively; difference, -1.6 percentage points; 95% confidence interval [CI], -7.1 to 3.8), and the rates of investigator-assessed clinical response at the post-treatment evaluation were 87.6% and 85.1%, respectively (difference, 2.5 percentage points; 95% CI, -2.4 to 7.4). Adverse events that emerged after treatment initiation were reported in 41.1% of the patients in the omadacycline group and 48.5% of the patients in the moxifloxacin group; the most frequent events were gastrointestinal (10.2% and 18.0%, respectively), and the largest difference was for diarrhea (1.0% and 8.0%). Twelve deaths (8 in the omadacycline group and 4 in the moxifloxacin group) occurred during the trial.

CONCLUSIONS

Omadacycline was noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia in adults. (Funded by Paratek Pharmaceuticals; OPTIC ClinicalTrials.gov number, NCT02531438 .).

Omadacycline: A New Tetracycline Antibiotic

OBJECTIVE

To review the chemistry, pharmacology, microbiology, pharmacokinetics, pharmacodynamics, clinical efficacy, tolerability, dosage, and administration of omadacycline, a new tetracycline antibiotic.

DATA SOURCES

A literature search through PubMed, Google Scholar, and clinicaltrials.gov was conducted (2008 to October 2018) using the search terms omadacycline and PTK-0796. Abstracts presented at recent conferences, prescribing information and information from the FDA and the manufacturer's website were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Preclinical data and published phase 1, 2, and 3 studies were evaluated.

DATA SYNTHESIS

Omadacycline displays in vitro activity against a wide range of bacteria. Clinical trials have shown that omadacycline is noninferior to linezolid for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia (CABP). A loading dose of 200 mg intravenously (IV) once or 100 mg IV twice or 450 mg orally once is recommended followed by a maintenance dose of 100 mg IV or 300 mg orally once daily. No dosage adjustment is needed in patients with renal or hepatic impairment. Omadacycline is well tolerated, with nausea being a common adverse effect, but is associated with food and drug interactions. Relevance to Patient Care and Clinical Practice: Omadacycline is active against staphylococci, including methicillin-resistant strains, and streptococci, including tetracycline-resistant strains, as well as atypical bacteria. Omadacycline provides clinicians with an additional parenteral and oral option for the treatment of adults with ABSSSI and CABP.

CONCLUSION

Omadacycline is an alternative treatment option for ABSSSI and CABP.

Suppressive antibiotic therapy with oral tetracyclines for prosthetic joint infections: a retrospective study of 78 patients

PURPOSE

This study aimed at describing the use of oral cyclines (i.e., doxycycline and minocycline) as suppressive antibiotic therapy (SAT) in patients with periprosthetic joint infections (PJIs).

METHODS

Medical charts of all patients with surgical revisions for PJIs who were given cycline-based SAT because of a high failure of various origins were reviewed. Data regarding tolerability and effectiveness of cycline-based SAT were analysed.

RESULTS

Seventy-eight patients of mean age 64 ± 17 years received cycline-base SAT in the period from January 2006 to January 2014. PJIs involved the knee in 37 patients (47%), the hip in 35 (45%), the elbow in 4 (5%), and the shoulder in 2 (3%) and were qualified as early in 31 patients (39.7%). Staphylococcus spp. were the most common pathogens accounting for 72.1% of the total number of bacterial strains identified. All included patients had surgery which consisted in debridement and implant retention in 59 of them (75.6%). Doxycycline and minocycline were prescribed as SAT in 72 (92%) and 6 (8%) patients, respectively. Adverse events were reported in 14 patients (18%), leading to SAT discontinuation in 6 of them (8%). After a mean follow-up of 1020 ± 597 days, a total of 22 (28.2%) patients had failed including 3 cases (3.8%) with documented acquisition of tetracycline resistance in initial pathogen(s).

CONCLUSIONS

Our results suggest that oral cyclines used as SAT in patients treated for PJI have an acceptable tolerability and effectiveness and appear to be a reasonable option in this setting.

Similarities and differences between doxycycline and minocycline: clinical and antimicrobial stewardship considerations

Doxycycline and, to a lesser extent, minocycline, have been used for decades to treat various serious systemic infections, but many physicians remain unfamiliar with their spectrum, interpretation of susceptibility results, pharmacokinetic/pharmacodynamic (PK/PD) properties, optimal dosing regimens, and their activity against MRSA, VRE, and multidrug-resistant (MDR) Gram-negative bacilli, e.g., Acinetobacter sp. This article reviews the optimal use of doxycycline and minocycline to treat a variety of infections and when minocycline is preferred instead of doxycycline.

Suppressive antibiotic therapy with oral doxycycline for Staphylococcus aureus prosthetic joint infection: a retrospective study of 39 patients

The aim of this study was to describe the use of oral doxycycline as suppressive antibiotic therapy (SAT) in patients with Staphylococcus aureus periprosthetic (hip or knee) joint infections. The medical charts of all patients with surgical revisions for S. aureus hip or knee prosthetic joint infections (PJIs) who were given doxycycline-based SAT because of a high risk of failure of various origins were reviewed. Data regarding tolerability and effectiveness of doxycycline-based SAT were analysed. A total of 39 patients (mean age 66.1 ± 16.3 years) received doxycycline-base SAT in the period from January 2006 to January 2014. PJIs involved the hip in 23 patients (59.0%) and the knee in 16 (41.0%), and were qualified as early in 15 patients (38.5%). Methicillin-resistant S. aureus (MRSA) accounted for 22% of the total number of bacterial strains identified. All patients included in the study had surgery, which consisted of debridement and implant retention in 32 (82.1%). Adverse events likely attributable to SAT were reported in six patients (15.4%), leading to discontinuation of SAT in three (7.7%). A total of 29 patients (74.4%) remained event-free and 10 (25.6%) failed, including 8 (20.5%) relapses and 2 (5.1%) superinfections. Overall, 8 of the 10 failure cases were related to a doxycycline-susceptible pathogen. These results suggest that oral doxycycline used as SAT in patients treated for S. aureus hip or knee PJIs has an acceptable tolerability and effectiveness and appears to be a reasonable option in this setting.

Does Adjunctive Tigecycline Improve Outcomes in Severe-Complicated, Nonoperative Clostridium difficile Infection?

Severe Clostridium difficile infection is associated with a high rate of mortality; however, the optimal treatment for severe- complicated infection remains uncertain for patients who are not candidates for surgical intervention. Thus, we sought to evaluate the benefit of adjunctive tigecycline in this patient population using a retrospective cohort adjusted for propensity to receive tigecycline. We found that patients who received tigecycline had similar outcomes to those who did not, although the small sample size limited power to adjust for comorbidities and severity of illness.

A General Method for Nucleophilic Aromatic Substitution of Aryl Fluorides and Chlorides with Dimethylamine using Hydroxide-Assisted Decomposition of N,N-Dimethylforamide

A practical and convenient procedure for the nucleophilic aromatic substitution of aryl fluorides and chlorides with dimethylamine was developed using a hydroxide assisted, thermal decomposition of N,N-dimethylforamide. These conditions are tolerant of nitro, nitrile, aldehyde, ketone, and amide groups but will undergo acyl substitution to form amides for methyl esters and acyl chlorides. Isolated yields of the products range from 44 - 98%, with the majority being greater than 70% for seventeen examples.