Answers
Samar Razaq in Difficult Cases in Primary Care, 2021
Lyme disease is caused by the spirochete bacterium Borrelia burgdorferi. B. burgdorferi is transferred to humans via the hard tick Ixodes dammini, which feeds on animals infected with the bacterium. Introduction of the bacterium into the human bloodstream via tick saliva occurs during a tick bite. Patients may recall this tick bite and the resultant macular lesion that appears at the site of the bite. This lesion then expands over the course of a week and develops into the characteristic rash of Lyme disease: erythema chronicum migrans. While this is occurring the patient may suffer from a prodromal phase in which there is fever and general malaise. The appearance of the typical rash should raise suspicions and trigger appropriate investigations that may include serology (to look for antibodies against the bacterium) and culture from appropriate fluid or tissue. Untreated, there is a significant risk of developing the late manifestations of Lyme disease, which include neurological abnormalities (e.g. meningitis, cranial neuropathy, peripheral neuropathy), heart disease (e.g. myocarditis, pericarditis, atrioventricular block) and rheumatological disease such as arthritis and fatigue. Rarely, the eyes, liver, spleen and testicles may also be involved. Doxycycline is the first-choice antibiotic. Summer forest walkers should be advised to cover up well and remove attached ticks promptly. Q fever is another bacterial zoonosis caused by the bacterium Coxiella burnetii.
Diagnostic Approach to Rash and Fever in the Critical Care Unit
Cheston B. Cunha, Burke A. Cunha in Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Prompt treatment with tetracycline decreases mortality [41,42]. Most patients’ defervesce within 2‒3 days, and these patients should receive treatment for at least 3 days after showing improvement [38,43]. Chloramphenicol, the only other antimicrobial agent recommended for the treatment of RMSF, causes gray baby syndrome and should not be used for pregnant women who are near term [43]. Gray baby syndrome occurs due to a lack of the necessary liver enzymes to metabolize chloramphenicol, resulting in drug accumulation, which leads to vomiting, ashen gray skin color, limp body tone, hypotension, cyanosis, hypothermia, cardiovascular collapse, and often death. Pregnant women who are near term may receive tetracycline because the risk of fetal damage or death is minimal. Previously, tetracycline is not recommended for pregnant women, in the first or second trimester, because of the effects on fetal bone and dental development [43]. However, doxycycline use during pregnancy probably does not pose substantial teratogenic risk [38]. Pregnant woman should be counseled about risks and benefits for treatment decision. Chloramphenicol can be administered in early pregnancy because gray baby syndrome is not a risk during the early period of fetal development [43].
Infectious Optic Neuropathies
Vivek Lal in A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Bartonella henselae is a gram-negative bacteria, which is known to cause the zoonotic cat-scratch disease.42 The Bartonella henselae organism is transmitted by the infected cats, through bites, licks or abrasions.42 The cat-scratch disease usually manifests with a flu-like syndrome along with tender lymphadenitis.43 Ocular involvement is described in 5 to 10% of patients.44 The ocular involvement in cat-scratch disease is common. There is a gap of about 4 weeks between inoculation and development of ocular complications. Neuroretinitis is the most common and most characteristic ocular complication.45 Patients can have vision loss, RAPD, color desaturation and visual field abnormalities. The fundus examination shows optic disc edema along with macular star formation. In majority of patients, vision recovers following treatment.46,47 The indirect fluorescent antibody test, enzyme-linked immunoassay (ELISA), Western blot and polymerase chain reaction (PCR)-based assays are used for the laboratory diagnosis.42,43 The treatment guidelines are not clear. Usually patients are treated with doxycycline.48 Alternatively, rifampicin, gentamycin, ciprofloxacin and trimethoprim-sulfamethoxazole have also been used.49
Safety of the subconjunctival injection of doxycycline in rabbits
Published in Cutaneous and Ocular Toxicology, 2019
Leila Ghiasian, Abbas Habibi, Roshanak Aliakbar Navahi, Ali Hadavandkhani, Shadi Akbarian, Sayyed Amirpooya Alemzadeh, Maryam Ashraf Khorasani
Doxycycline is a semi-synthetic antibiotic from the second generation of the Tetracycline group, which is highly in use, because of its broad-spectrum antibiotic impression, in clinical practice4. It is reported that Doxycycline has far more anti-collagenase effect on rabbits’ cornea compared to that of Tetracycline and Minocycline9. Also, Doxycycline, Minocycline, and Tetracycline contain multiple phenolic rings, resembling vitamin E structure, which play a key role in eliminating free oxygen radicals10. On the other hand, oral Doxycycline has a proved impact on the treatment of surface inflammatory eye diseases, such as chronic blepharitis, Meibomian gland dysfunction, Rosacea eye and recurrent corneal erosion; however, several side effects have been reported to the oral application11.
Acute bacterial skin and skin structure infections in pediatric patients: potential role of dalbavancin
Published in Expert Review of Anti-infective Therapy, 2023
Lorenzo Volpicelli, Mario Venditti, Alessandra Oliva
Doxycycline and minocycline comprise the second generation of tetracyclines, which is characterized by prolonged half-life, good oral bioavailability, and excellent lipid solubility. A full therapeutic effect is reached after 4–5 serum half-lives and for this reason, when a serious infection is suspected, both drugs require therapy to be started with a loading dose, followed by a maintenance dose [27]. Compared to doxycycline, minocycline has the highest tissue penetration and possesses enhanced antimicrobial activity against multidrug-resistant (MDR) pathogens, including the Gram-negative Acinetobacter baumannii and Gram-positives, such as MRSA and vancomycin-resistant Enterococcus [27]. Tetracycline prescription to children <8 years has historically been contraindicated because of permanent tooth discoloration caused by drug incorporation in enamel. In recent years, new data strongly downsized the risk connected to doxycycline so much that now the American Academy of Pediatrics recommends doxycycline to be safely administered for short durations (≤21 days) regardless of age [28]. A common side effect of doxycycline is gastrointestinal upset [27]. As for minocycline, vestibular side effects are relatively common, while minocycline-induced autoimmunity is a rare but serious event [27].
Scrub typhus and antibiotic-resistant Orientia tsutsugamushi
Published in Expert Review of Anti-infective Therapy, 2021
Chin-Te Lu, Lih-Shinn Wang, Po-Ren Hsueh
The poor response to doxycycline may result from infections with doxycycline-resistant or particularly virulent strains, inadequate doxycycline concentrations, more severe disease, and infected host-related factors [94]. If doxycycline resistance does not exist, other factors may explain why poor treatment outcomes are observed in clinical practice. Bacterial factors, such as the virulence diversity of O. tsutsugamushi isolates, also affect treatment outcomes. It has been reported that AFC-3 and AFSC-4 have high infectivity and short doubling times [86,95]. It has been suggested that while routine dosage of doxycycline may be adequate for the treatment of severe cases [96], the optimal choice of antibiotics and dosage for treatment remains unclear. Further pharmacological studies and high-quality clinical trials for the treatment of scrub typhus are urgently required.
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