Efficacy of linezolid on Treponema pallidum, the syphilis agent: A preclinical study.

BACKGROUND: Penicillin G, the current standard treatment for syphilis, has important drawbacks, but virtually no preclinical or clinical studies have been performed to identify viable alternatives. We tested, both in vitro and in vivo, three marketed antibiotics with adequate pharmacological properties to treat syphilis. METHODS: We used an in vitro culturing system of T. pallidum to perform drug susceptibility testing and applied quantitative PCR targeting the tp0574 gene to measure bacterial growth. To confirm in vivo efficacy, fifteen rabbits were infected intradermally with T. pallidum at eight sites each and randomly allocated to an experimental treatment (linezolid, moxifloxacin, clofazimine) or a control arm (benzathine penicillin G [BPG], untreated). The primary outcome was treatment efficacy defined as the time to lesion healing measured from the date of treatment start. Secondary outcomes were absence of treponemes or treponemal mRNA in injection sites, absence of seroconversion, and cerebrospinal fluid (CSF) abnormalities and negative rabbit infectivity tests (RIT). FINDINGS: Linezolid showed in vitro bactericidal activity at concentrations of 0.5 µg/mL or higher. When administered orally to experimentally infected rabbits, it induced healing of early lesions at a time similar to BPG (hazard ratio 3.84; 95% CI 2.05-7.17; p < 0.0001 compared to untreated controls). In linezolid-treated animals, dark-field microscopy and qPCR assessment showed no presence of treponemes after day 3 post-treatment start, serologic test did not convert to positive, CSF had no abnormalities, and RIT was negative. Moxifloxacin and clofazimine failed to inhibit bacterial growth in vitro and could not cure the infection in the rabbit model. INTERPRETATION: Linezolid, a low-cost oxazolidinone, has in vitro and in vivo activity against T. pallidum, with efficacy similar to BPG in treating treponemal lesions in the animal model. Our findings warrant further research to assess the efficacy of linezolid as an alternative to penicillin G to treat syphilis in human clinical trials. FUNDING: European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant agreement No. 850450).

Macrolide Resistance in Treponema pallidum Correlates With 23S rDNA Mutations in Recently Isolated Clinical Strains.

BACKGROUND: High rates of 23S rDNA mutations implicated in macrolide resistance have been identified in Treponema pallidum samples from syphilis patients in many countries. Nonetheless, some clinicians have been reluctant to abandon azithromycin as a treatment for syphilis, citing the lack of a causal association between these mutations and clinical evidence of drug resistance. Although azithromycin resistance has been demonstrated in vivo for the historical Street 14 strain, no recent T. pallidum isolates have been tested. We used the well-established rabbit model of syphilis to determine the in vivo efficacy of azithromycin against 23S rDNA mutant strains collected in 2004 to 2005 from patients with syphilis in Seattle, Wash. METHODS: Groups of 9 rabbits were each infected with a strain containing 23S rDNA mutation A2058G (strains UW074B, UW189B, UW391B) or A2059G (strains UW228B, UW254B, and UW330B), or with 1 wild type strain (Chicago, Bal 3, and Mexico A). After documentation of infection, 3 animals per strain were treated with azithromycin, 3 were treated with benzathine penicillin G, and 3 served as untreated control groups. Treatment efficacy was documented by darkfield microscopic evidence of T. pallidum, serological response, and rabbit infectivity test. RESULTS: Azithromycin uniformly failed to cure rabbits infected with strains harboring either 23S rDNA mutation, although benzathine penicillin G was effective. Infections caused by wild type strains were successfully treated by either azithromycin or benzathine penicillin G. CONCLUSIONS: A macrolide resistant phenotype was demonstrated for all strains harboring a 23S rDNA mutation, demonstrating that either A2058G or A2059G mutation confers in vivo drug resistance.

Jarisch-Herxheimer reaction among HIV-positive patients with early syphilis: azithromycin versus benzathine penicillin G therapy.

INTRODUCTION: The Jarisch-Herxheimer reaction, a febrile inflammatory reaction that often occurs after the first dose of chemotherapy in spirochetal diseases, may result in deleterious effects to patients with neurosyphilis and to pregnant women. A single 2-g oral dose of azithromycin is an alternative treatment to benzathine penicillin G for early syphilis in areas with low macrolide resistance. With its potential anti-inflammatory activity, the impact of azithromycin on the incidence of the Jarisch-Herxheimer reaction in HIV-positive patients with early syphilis has rarely been investigated. METHODS: In HIV-positive patients with early syphilis, the Jarisch-Herxheimer reaction was prospectively investigated using the same data collection form in 119 patients who received benzathine penicillin G between 2007 and 2009 and 198 who received azithromycin between 2012 and 2013, when shortage of benzathine penicillin G occurred in Taiwan. Between 2012 and 2013, polymerase chain reaction (PCR) assay was performed to detect Treponema pallidum DNA in clinical specimens, and PCR restriction fragment length polymorphism of the 23S ribosomal RNA was performed to detect point mutations (2058G or A2059G) that are associated with macrolide resistance. RESULTS: The overall incidence of the Jarisch-Herxheimer reaction was significantly lower in patients receiving azithromycin than those receiving benzathine penicillin G (14.1% vs. 56.3%, p<0.001). The risk increased with higher rapid plasma reagin (RPR) titres (adjusted odds ratio [AOR] per 1-log2 increase, 1.21; confidence interval [CI], 1.04-1.41), but decreased with prior penicillin therapy for syphilis (AOR, 0.37; 95% CI, 0.19-0.71) and azithromycin treatment (AOR, 0.15; 95% CI, 0.08-0.29). During the study period, 310 specimens were obtained from 198 patients with syphilis for PCR assays, from whom T. pallidum was identified in 76 patients, one of whom (1.3%) was found to be infected with T. pallidum harbouring the macrolide resistance mutation (A2058G). In subgroup analyses confined to the 75 patients infected with T. pallidum lacking resistance mutation, a statistically significantly lower risk for the Jarisch-Herxheimer reaction following azithromycin treatment was noted. CONCLUSIONS: Treatment with azithromycin was associated with a lower risk for the Jarisch-Herxheimer reaction than that with benzathine penicillin G in HIV-positive patients with early syphilis. Previous benzathine penicillin G therapy for syphilis decreased the risk, whereas higher RPR titres increased the risk, for the reaction.

Prevalence of the 23S rRNA A2058G point mutation and molecular subtypes in Treponema pallidum in the United States, 2007 to 2009.

BACKGROUND: The 23S rRNA A2058G point mutation in Treponema pallidum is associated with macrolide antibiotic treatment failure. Its prevalence and potential association with a molecular subtype within the United States are unknown. METHODS: During 2007 to 2009, 11 clinics across the United States sent samples from genital ulcers to the Centers for Disease Control and Prevention. Molecular techniques were used to identify T. pallidum DNA sequences, the A2058G mutation, and subtype of T. pallidum. Accompanying epidemiologic information was abstracted from medical records. RESULTS: A total of 141 samples with T. pallidum were collected from individuals whose median age was 33 years (range, 13-68 years): 118 were male (69% reported as men having sex with men [MSM]). The A2058G mutation was carried in 75 samples (53%) with T. pallidum, with samples from MSM (versus women and other men) more likely carrying the A2058G mutation (65/82 samples versus 8/57 samples; prevalence ratio, 5.7; 95% confidence interval, 2.9-10.8). Of 98 strain-typed samples, 61 (62%) were the 14d9 subtype of T. pallidum, which was also associated with samples with T. pallidum from MSM (prevalence ratio, 3.5; 95% confidence interval, 1.9-6.5). However, among T. pallidum from MSM, the A2058G mutation was not associated with the 14d9 subtype. CONCLUSIONS: The A2058G mutation and 14d9 subtype of T. pallidum were present throughout the United States. Both were more commonly found in T. pallidum from MSM compared with women or other men but were not associated with each other. Treating syphilis with azithromycin should be done cautiously and only when treatment with penicillin or doxycycline is not feasible.

Effect of benzathine penicillin treatment on antibiotic susceptibility of viridans streptococci in oral flora of patients receiving secondary prophylaxis after rheumatic fever.

OBJECTIVE: To assess the level of antibiotic resistance of viridans streptococci in the oral flora of children with a history of rheumatic fever, receiving long-term monthly intramuscular benzathine penicillin G prophylaxis. PATIENTS AND METHODS: Oral swabs from patients receiving monthly penicillin G prophylaxis for rheumatic fever were cultured and tested for viridans streptococci. The E-test was used to test susceptibility to penicillin G, clindamycin, clarithromycin and rifampin. Findings were compared with samples from healthy children who had not been exposed to antibiotic treatment for at least 2 months. RESULTS: Twenty-six patients and 20 control children were included in the study. Duration of intramuscular antibiotic treatment ranged from 5 months to 13.5 years. Sixty isolates of viridans streptococci species were obtained, with a similar distribution in the two groups. Intermediate resistance to penicillin (MIC 0.25-2 mg/L) was documented in 10 of the 32 isolates (31.2%) in the study group, and high resistance in none, compared to seven of 28 isolates (25%) with intermediate or high resistance in the control group (p=NS). All isolates in the study group and all but one in the control group were susceptible to clindamycin, and all isolates from both groups were susceptible to rifampin. One isolate (3.1%) in the study group and two (7.1%) in the control group were resistant to clarithromycin. CONCLUSION: Monthly Intramuscular penicillin prophylaxis has no effect on the antibiotic susceptibility of viridans streptococci in oral flora in children with a history of rheumatic fever, receiving secondary prophylaxis after rheumatic fever, regardless of the duration of treatment.

A new insight about pharmaceutical dosage forms for benzathine penicillin G

O objetivo desse trabalho foi o de desenvolver e avaliar do ponto de vista físico-químico um sistema micelar de penicilina G benzatina (BPG) em desoxicolato de sódio (NaDC).Foram estudadas as características físicoquímicas da BPG quanto à solubilidade em água e em soluções tampões com diferentes pHs, além do coeficiente de partição octanol-água.Foram avaliadas as propriedades da concentração micelar crítica (CMC) das soluções micelares de Desoxicolato de sódio (NaDC) em baixa e alta força iônica provocada pela presença de cloreto de sódio.O estudo da incorporação da BPG em soluções micelares de NaDC usando várias concentrações de NaDC também foi realizado.O aumento da solubilidade da BPG provocada pela presença de micelas de NaDC foi analisada quantitativamente pelo formalismo do modelo de pseudo-fase.Houve indicação da aplicabilidade do sistema micelar estudado quanto à incorporação de penicilina e aumento se sua solubilidade aparente, com taxa de incorporação de até 90 por cento.Espera-se que a formulação micellar de BPG apresente melhor estabilidade, considerando-se que o antibiótico incorporado na região hidrofóbica das micelas está protegido do meio aquoso externo.

Infection with Leishmania infantum Inhibits actinomycin D-induced apoptosis of human monocytic cell line U-937.

Modulation of host cell apoptosis has been observed in many bacterial, protozoal, and viral infections. The aim of this work was to investigate the effect of viscerotropic Leishmania (L.) infantum infection on actinomycin D-induced apoptosis of the human monocytic cell line U-937. Cells were infected with L. infantum promastigotes or treated with the surface molecule lipophosphoglycan (LPG) or with parasite-free supernatant of Leishmania culture medium and submitted to action of actinomycin D as the apoptosis-inducing agent. Actinomycin D-induced apoptosis in U-937 cells was inhibited in the presence of both viable L. infantum promastigotes and soluble factors contained in Leishmania culture medium or purified LPG. Leishmania infantum affected the survival of U-937 cells via a mechanism involving inhibition of caspase-3 activation. Furthermore, protein kinase C delta (PKC delta) cleavage was increased in actinomycin D-treated U-937 cells and was inhibited by the addition of LPG. Thus, inhibition of the PKC-mediated pathways by LPG can be implicated in the enhanced survival of the parasites. These results support the claim that promastigotes of L. infantum, as well as its surface molecule, LPG, which is in part released in the culture medium, inhibit macrophage apoptosis, thus allowing intracellular parasite survival and replication.

Investigation of DNA damage in lymphocytes exposed to benzathine penicillin G.

BACKGROUND: Benzathine penicillin G (BPG) is a widely used antibiotic for treatment or prophylaxis of certain infectious diseases. Previous in vivo studies using sister chromatid exchange (SCE) frequency and comet assay, had showed that long-term administration of benzathine penicillin G may cause some degree of DNA damage in children with rheumatic fever. METHODS: Because DNA damage has also been reported in various connective tissue disorders, to rule out the possible effects of underlying disease on DNA integrity, 3-day-cultured lymphocytes obtained from nine healthy individuals were exposed to BPG at different concentrations (0.002, 0.02 and 0.1 micro g/mL), and sister chromatid exchange frequencies were studied. The mean SCE frequency per metaphase was calculated from 20 selected cells for each individual. RESULTS: The incidence of SCE frequency did not differ when all groups were compared. Comparing between each concentration group, exposure to BPG did not cause a dose-dependent increase in SCE frequency (Student's t-test, P > 0.05). CONCLUSION: Insignificant changes (P > 0.05) in SCE, within the 3-day exposure to BPG, may suggest that DNA damage did not occur. Short-term exposure to BPG does not have toxic effects on DNA. In contrast, this preliminary study should be supported by other genotoxicity assays, expanding the exposure time to longer periods, in order to exclude rapid DNA repair mechanisms. and a possible role of underlying disease on DNA integrity should not be ignored.

Unexplained reduced microbiological efficacy of intramuscular benzathine penicillin G and of oral penicillin V in eradication of group a streptococci from children with acute pharyngitis.

OBJECTIVE: To evaluate the efficacy of oral penicillin V and intramuscular benzathine penicillin G (BPG) in eradicating group A streptococci from the upper respiratory tract. METHODOLOGY: Two randomized, single-blind, multicenter antibiotic efficacy trials in children using recommended doses of either oral penicillin V or intramuscular BPG for treatment of acute-onset pharyngitis associated with isolation of group A streptococci were conducted. Throat examinations and cultures were obtained at enrollment and on days 5 to 8, 10 to 14, and 29 to 31. RESULTS: Thirty-five percent of 284 evaluable patients treated with oral penicillin V and 37% of BPG-treated patients were microbiologic treatment failures at either 10 to 14 or 29 to 31 days. CONCLUSIONS: Although these findings do not provide sufficient evidence to change current treatment recommendations or public health policy, important questions are raised about currently recommended penicillin doses, about the role of the carrier state, and possibly about adequate bioavailability of intramuscular BPG. These findings require confirmation.

Sifilis maligna: presentación previa a seroconversión en HIV / Malignant syphilis: previus presentation a seroconvertion in HIV

La sífilis maligna es una infrecuente forma de sífilis secundaria caracterizada por lesiones nóduloulcerativas destructivas, compromiso del estado general y curso agresivo sin tratamiento. Actualmente se la observa con mayor frecuencia asociada a la inmunodepresión por el virus del sida. Presentamos una paciente de 27 años de edad que desarrolló la enfermedad en forma previa a la seroconversión para HIV

Sifilis maligna: presentación previa a seroconversión en HIV / Malignant syphilis: previus presentation a seroconvertion in HIV

La sífilis maligna es una infrecuente forma de sífilis secundaria caracterizada por lesiones nóduloulcerativas destructivas, compromiso del estado general y curso agresivo sin tratamiento. Actualmente se la observa con mayor frecuencia asociada a la inmunodepresión por el virus del sida. Presentamos una paciente de 27 años de edad que desarrolló la enfermedad en forma previa a la seroconversión para HIV(AU)

Sífilis e infección por el virus de la inmunodeficiencia humana. Presentación de tres casos con clínica atípica / Syphilis and human immunodeficiency virus infection. Report of three cases with unusual clinical features

Se describen tres pacientes con sífilis e infección por el virus de la inmunodeficiencia humana (VIH) en los que resaltamos su peculiar presentación clínica. En el primero de ellos destaca la coexistencia de estas dos infecciones con una mucinosis papulosa. En el segundo, la clínica cutánea, con lesiones tuberoulcerosas persistente y placas eritematovioláceas, semejantes a una sífilis terciaria. El tercero debutó con lesiones orales erosivoulcerosas de repetición. En los dos primeros pacientes las manifestaciones cutáneas fueron el primer signo de infección por sífilis y VIH. Queremos llamar la atención sobre la variedad clínica de presentación de la sífilis en pacientes VIH positivos (AU)

Falso positivo en los análisis de anfetamina urinaria debido a penicilina G benzatina / False positive on urinary amphetamine due to benzathine penicilin G

No disponible