Pythium insidiosum: In vitro oomicidal evaluation of telithromycin and interactions with azithromycin and amorolfine hydrochloride

This study evaluated the repositioning of the ketolide antibacterial telithromycin (TLT) against the oomycete Pythium insidiosum and verified the combination of TLT and the antimicrobials azithromycin (AZM) and amorolfine hydrochloride (AMR), which have known anti-P. insidiosum activity. Susceptibility tests of P. insidiosum isolates (n = 20) against the drugs were carried out according to CLSI protocol M38-A2, and their combinations were evaluated using the checkerboard microdilution method. The minimum inhibitory concentrations were 0.5-4 µg/mL for TLT, 2-32 µg/mL for AZM, and 16-64 µg/mL for AMR. For the TLT+AZM combination, 52.75 % of interactions were indifferent, 43.44 % were antagonistic, and 9.70 % were synergistic. As for interactions of the TLT+AMR combination, 60.43 % were indifferent, 39.12 % were antagonistic, and 10.44 % synergistic interactions. This study is the first to evaluate the repositioning of the antibacterial TLT against mammalian pathogenic oomycetes, and our results show that its isolated action is superior to its combinations with either AZM or AMR. Therefore, we recommend including TLT in future research to evaluate therapeutic approaches in different clinical forms of human and animal pythiosis.

Azithromycin preserves adult hippocampal neurogenesis and behavior in a mouse model of sepsis

The mammalian hippocampus can generate new neurons throughout life. Known as adult hippocampal neurogenesis (AHN), this process participates in learning, memory, mood regulation, and forgetting. The continuous incorporation of new neurons enhances the plasticity of the hippocampus and contributes to the cognitive reserve in aged individuals. However, the integrity of AHN is targeted by numerous pathological conditions, including neurodegenerative diseases and sustained inflammation. In this regard, the latter causes cognitive decline, mood alterations, and multiple AHN impairments. In fact, the systemic administration of Lipopolysaccharide (LPS) from E. coli to mice (a model of sepsis) triggers depression-like behavior, impairs pattern separation, and decreases the survival, maturation, and synaptic integration of adult-born hippocampal dentate granule cells. Here we tested the capacity of the macrolide antibiotic azithromycin to neutralize the deleterious consequences of LPS administration in female C57BL6J mice. This antibiotic exerted potent neuroprotective effects. It reversed the increased immobility time during the Porsolt test, hippocampal secretion of pro-inflammatory cytokines, and AHN impairments. Moreover, azithromycin promoted the synaptic integration of adult-born neurons and functionally remodeled the gut microbiome. Therefore, our data point to azithromycin as a clinically relevant drug with the putative capacity to ameliorate the negative consequences of chronic inflammation by modulating AHN and hippocampal-related behaviors.

Rolling the evolutionary dice: Neisseria commensals as proxies for elucidating the underpinnings of antibiotic resistance mechanisms and evolution in human pathogens

Species within the genus Neisseria are adept at sharing adaptive allelic variation, with commensal species repeatedly transferring resistance to their pathogenic relative Neisseria gonorrhoeae. However, resistance in commensals is infrequently characterized, limiting our ability to predict novel and potentially transferable resistance mechanisms that ultimately may become important clinically. Unique evolutionary starting places of each Neisseria species will have distinct genomic backgrounds, which may ultimately control the fate of evolving populations in response to selection as epistatic and additive interactions coerce lineages along divergent evolutionary trajectories. Alternatively, similar genetic content present across species due to shared ancestry may constrain existing adaptive solutions. Thus, identifying the paths to resistance across commensals may aid in characterizing the Neisseria resistome-or the reservoir of alleles within the genus as well as its depth. Here, we use in vitro evolution of four commensal species to investigate the potential and repeatability of resistance evolution to two antimicrobials, the macrolide azithromycin and the β-lactam penicillin. After 20 days of selection, commensals evolved resistance to penicillin and azithromycin in 11/16 and 12/16 cases, respectively. Almost all cases of resistance emergence converged on mutations within ribosomal components or the mtrRCDE efflux pump for azithromycin-based selection and mtrRCDE, penA, and rpoB for penicillin selection, thus supporting constrained adaptive solutions despite divergent evolutionary starting points across the genus for these particular drugs. Though drug-selected loci were limited, we do identify novel resistance-imparting mutations. Continuing to explore paths to resistance across different experimental conditions and genomic backgrounds, which could shunt evolution down alternative evolutionary trajectories, will ultimately flesh out the full Neisseria resistome.IMPORTANCENeisseria gonorrhoeae is a global threat to public health due to its rapid acquisition of antibiotic resistance to all first-line treatments. Recent work has documented that alleles acquired from close commensal relatives have played a large role in the emergence of resistance to macrolides and beta-lactams within gonococcal populations. However, commensals have been relatively underexplored for the resistance genotypes they may harbor. This leaves a gap in our understanding of resistance that could be rapidly acquired by the gonococcus through a known highway of horizontal gene exchange. Here, we characterize resistance mechanisms that can emerge in commensal Neisseria populations via in vitro selection to multiple antimicrobials and begin to define the number of paths to resistance. This study, and other similar works, may ultimately aid both surveillance efforts and clinical diagnostic development by nominating novel and conserved resistance mechanisms that may be at risk of rapid dissemination to pathogen populations.

Azithromycin reduces hemoglobin-induced innate neuroimmune activation

Neonatal intraventricular hemorrhage (IVH) releases blood products into the lateral ventricles and brain parenchyma. There are currently no medical treatments for IVH and surgery is used to treat a delayed effect of IVH, post-hemorrhagic hydrocephalus. However, surgery is not a cure for intrinsic brain injury from IVH, and is performed in a subacute time frame. Like many neurological diseases and injuries, innate immune activation is implicated in the pathogenesis of IVH. Innate immune activation is a pharmaceutically targetable mechanism to reduce brain injury and post-hemorrhagic hydrocephalus after IVH. Here, we tested the macrolide antibiotic azithromycin, which has immunomodulatory properties, to reduce innate immune activation in an in vitro model of microglial activation using the blood product hemoglobin (Hgb). We then utilized azithromycin in our in vivo model of IVH, using intraventricular blood injection into the lateral ventricle of post-natal day 5 rat pups. In both models, azithromycin modulated innate immune activation by several outcome measures including mitochondrial bioenergetic analysis, cytokine expression and flow cytometric analysis. This suggests that azithromycin, which is safe for neonates, could hold promise for modulating innate immune activation after IVH.

Emergence of high-level azithromycin-resistant Neisseria gonorrhoeae causing male urethritis in Johannesburg, South Africa, 2021

BACKGROUND

In South Africa, Neisseria gonorrhoeae , which is the predominant cause of male urethritis, is treated syndromically using dual ceftriaxone and azithromycin therapy. We determined antimicrobial susceptibilities of N. gonorrhoeae isolates from urethral discharge specimens, and genetically characterised those with elevated minimum inhibitory concentrations (MICs) for first-line antimicrobials.

METHODS

Routine antimicrobial susceptibility testing (AST) of N. gonorrhoeae isolates included E-test for ceftriaxone, cefixime and gentamicin and agar dilution for azithromycin and spectinomycin. Neisseria gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR) was performed for isolates with elevated MICs to identify antimicrobial resistance (AMR) determinants, and Neisseria gonorrhoeae Multi-Antigen Sequence Typing (NG-MAST) was used to determine strain relatedness.

RESULTS

N. gonorrhoeae was cultured from urethral discharge swab specimens obtained from 196 of 238 (82.4%) men presenting to a primary healthcare facility in Johannesburg in 2021. All viable isolates were susceptible to extended-spectrum cephalosporins. Four isolates had high azithromycin MICs ranging from 32mg/L to >256mg/L and grouped into two novel NG-MAST and NG-STAR groups. Two isolates from Group 1 (NG-MAST ST20366, NG-STAR ST4322) contained mutated mtrR (G45D) and 23S rRNA (A2059G) alleles, while the two isolates from Group 2 (NG-MAST ST20367, NG-STAR ST4323) had different mutations in mtrR (A39T) and 23S rRNA (C2611T).

CONCLUSIONS

We report the first cases of high-level azithromycin resistance in N. gonorrhoeae from South Africa. Continued AMR surveillance is critical to detect increasing azithromycin resistance prevalence in N. gonorrhoeae , which may justify future modifications to the STI syndromic management guidelines.

Azithromycin regulates bacterial virulence and immune response in a murine model of ceftazidime-treated Pseudomonas aeruginosa acute pneumonia

Pseudomonas aeruginosa (PA) remains one of the leading causes of nosocomial acute pneumonia. The array of virulence factors expressed by PA and the intense immune response associated with PA pneumonia play a major role in the severity of these infections. New therapeutic approaches are needed to overcome the high resistance of PA to antibiotics and to reduce the direct damage to host tissues. Through its immunomodulatory and anti-virulence effects, azithromycin (AZM) has demonstrated clinical benefits in patients with chronic PA respiratory infections. However, there is relatively little evidence in PA acute pneumonia. We investigated the effects of AZM, as an adjunctive therapy combined with ceftazidime (CAZ), in a murine model of PA acute pneumonia. We observed that the combined therapy (i) reduces the weight loss of mice 24 h post-infection (hpi), (ii) decreases neutrophil influx into the lungs at 6 and 24 hpi, while this effect is absent in a LPS-induced pneumonia or when PA is pretreated with antibiotics and mice do not receive any antibiotics, and that (iii) AZM, alone or with CAZ, modulates the expression of PA quorum sensing regulators and virulence factors (LasI, LasA, PqsE, PhzM, ExoS). Our findings support beneficial effects of AZM with CAZ on PA acute pneumonia by both bacterial virulence and immune response modulations. Further investigations are needed to clarify the exact underlying mechanisms responsible for the reduction of the neutrophils influx and to better discriminate between direct immunomodulatory properties of AZM, and indirect effects on neutrophilia resulting from bacterial virulence modulation.

Antimicrobial resistance rates of urogenital Mycoplasma hominis and Ureaplasma species before and during the COVID-19 pandemic: results from a Greek survey, 2014 to 2022

The prevalence of antibiotic-resistant urogenital mycoplasmas and ureaplasmas has been gradually increasing over the years, leading to greater concern for accurate diagnosis and treatment. In this study, the antimicrobial resistance trends in Greece were analyzed using 2992 Ureaplasma spp. and 371 M. hominis isolates collected between 2014 and 2022. Antibiotic sensitivity was determined using eight different antimicrobial agents (josamycin, pristinamycin, clindamycin, ofloxacin, azithromycin, tetracycline, erythromycin, and doxycycline), with the data analyzed using descriptive statistical methods. Resistance rates to clindamycin and erythromycin increased for both M. hominis and Ureaplasma spp., while remaining relatively low for Tetracycline, Doxycycline, and Ofloxacin. For Ureaplasma spp., high susceptibility was observed to pristinamycin, tetracycline, doxycycline, azithromycin, and josamycin, and intermediate susceptibility to erythromycin. However, the resistance rate for clindamycin dramatically increased from 60% in 2014 to a peak of 98.46% in 2021, and the erythromycin resistance rate increased from 9.54% in 2018 to 22.13% in 2021. M. hominis exhibited consistently high resistance rates to Erythromycin, while Azithromycin resistance significantly increased over time, from 52.78% in 2017 to 97.22% in 2022. The alarming escalation in antibiotic-resistant urogenital mycoplasmas and ureaplasmas in the Greek population is a significant concern. Antibiotic overconsumption may have played a crucial role in increasing resistance trends. The implementation of nationwide surveillance systems, proper antibiotic stewardship policies, and appropriate culture-based therapy policies are necessary to effectively control this emerging risk.

Enhanced clearance of C. muridarum infection using azithromycin-loaded liposomes

Chlamydia trachomatis is an intracellular bacterium which infects around 129 million people annually. Despite similar infection rates between sexes, most research investigating the effects of chlamydial infection on fertility has focused on females. There is now emerging evidence of a potential link between Chlamydia and impaired male fertility. The only treatments for chlamydial infection are antibiotics, with azithromycin (AZI) being one of the commonly used drugs. However, recent studies have suggested that optimizing the treatment regime is necessary, as higher concentrations of AZI may be required to effectively clear the infection in certain cell types, particularly testicular macrophages. To address this challenge, we have prepared liposomes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) loaded with AZI for clearing Chlamydia. These liposomes exhibited stability over time and were readily taken up by both macrophages and epithelial cells. Moreover, they demonstrated significant enhancement of chlamydial clearance in both cell types. In a mouse model, the drug-loaded liposomes cleared Chlamydia within the penile urethra more efficiently than the same dose of unencapsulated drug. Furthermore, the liposome-drug treatment showed significant protective effects on sperm motility and morphology, suggesting potential benefits in reducing sperm damage caused by the infection.

[Establishment and Evaluation of a Resazurin-Based Microdilution Assay for Microbial Sensitivity Test of Neisseria gonorrhoeae]

Objective

To establish and evaluate a microbial sensitivity test method for Neisseria gonorrhoeae based on resazurin coloration.

Methods

Based on the broth microdilution method, resazurin was added as a live bacteria indicator. WHO G, a WHO gonococcal reference strain, was used to optimize the incubation time for resazurin-stained bacteria and the color change was visually observed to obtain the results. Agar dilution method (the gold standard) and resazurin-based microdilution assay were used to determine the minimum inhibitory concentration (MIC) of azithromycin, ceftriaxone, and spectinomycin for 3 reference strains and 32 isolates of Neisseria gonorrhoeae. The results were analyzed based on essential agreement (EA), which reflected the consistency of the MIC values, category agreement (CA), which reflected the consistency in the determination of drug resistance, intermediary, and sensitivity, very major error (VME), which reflected false sensitivity, and major error (ME), which reflected pseudo drug resistance, to evaluate the accuracy of resazurin-based microdilution assay as a microbial sensitivity test of of Neisseria gonorrhoeae. CA and EA rates≥90% and VME and ME rates≤3% were found to be the acceptable performance rates.

Results

The results obtained 6 hours after resazurin was added were consistent with those of the agar dilution method and the resazurin-based microdilution assay was established accordingly based on this parameter. The EA of resazurin-based microdilution assay for measuring the MIC results of azithromycin, ceftriaxone, and spectinomycin was 97.1%, 91.5%, and 94.3%, respectively, and the CA was 88.6%, 94.3%, and 94.3%, respectively. The VME was 0% for all three antibiotics, while the ME was 11.4%, 5.7%, and 5.7%, respectively.

Conclusion

The resazurin-based microdilution assay established in this study showed good agreement with agar dilution method for measuring the MIC of antibiotics against Neisseria gonorrhoeae. Moreover, the sensitivity results of this method were highly reliable and could be easily obtained through naked eye observation. Nonetheless, the results of drug resistance should be treated with caution and the optimization of parameters should be continued.

Genetic diversity of macrolides resistant Staphylococcus aureus clinical isolates and the potential synergistic effect of vitamins, C and K3

BACKGROUND

Macrolide antibiotics have been extensively used for the treatment of Staphylococcus aureus infections. However, the emergence of macrolide-resistant strains of S. aureus has become a major concern for public health. The molecular mechanisms underlying macrolide resistance in S. aureus are complex and diverse, involving both target site modification and efflux pump systems. In this study, we aim to overcome the molecular diversity of macrolide resistance mechanisms in S. aureus by identifying common molecular targets that could be exploited for the development of novel therapeutics.

METHODS

About 300 Staphylococcus aureus different isolates were recovered and purified from 921 clinical specimen including urine (88), blood (156), sputum (264), nasal swabs (168), pus (181) and bone (39) collected from different departments in Tanta University Hospital. Macrolide resistant isolates were detected and tested for Multi Drug Resistant (MDR). Gel electrophoresis was performed after the D test and PCR reaction for erm(A), (B), (C), msr(A), and mph(C) genes. Finally, we tried different combinations of Erythromycin or Azithromycin antibiotics with either vitamin K3 or vitamin C.

RESULTS

Macrolide resistance S. aureus isolates exhibited 7 major resistance patterns according to number of resistance markers and each pattern included sub patterns or subgroups. The PCR amplified products of different erm genes; analysis recorded different phenotypes of the Staphylococcus aureus isolates according to their different genotypes. In addition, our new tested combinations of Erythromycin and vitamin C, Erythromycin, and vitamin K3, Azithromycin and vitamin C and Azithromycin and vitamin K3 showed significant antibacterial effect when using every antibiotic alone. Our findings provide new insights into the molecular mechanisms of macrolide resistance in S. aureus and offer potential strategies for the development of novel protocols to overcome this emerging public health threat.

Antimicrobial susceptibility profile of Neisseria gonorrhoeae from patients attending a medical laboratory, Institut Pasteur de Madagascar between 2014 and 2020: phenotypical and genomic characterisation in a subset of Neisseria gonorrhoeae isolates

OBJECTIVES

Antimicrobial-resistant Neisseria gonorrhoeae (NG) is a concern. Little is known about antimicrobial susceptibility profiles and associated genetic resistance mechanisms of NG in Madagascar. We report susceptibility data of NG isolates obtained by the medical laboratory (CBC) of the Institut Pasteur de Madagascar, Antananarivo, Madagascar, during 2014-2020. We present antimicrobial resistance mechanisms data and phenotype profiles of a subset of isolates.

METHODS

We retrieved retrospective data (N=395) from patients with NG isolated during 2014-2020 by the CBC. We retested 46 viable isolates including 6 found ceftriaxone and 2 azithromycin resistant, as well as 33 isolated from 2020. We determined minimal inhibitory concentrations for ceftriaxone, ciprofloxacin, azithromycin, penicillin, tetracycline and spectinomycin using Etest. We obtained whole-genome sequences and identified the gene determinants associated with antimicrobial resistance and the sequence types (STs).

RESULTS

Over the study period, ceftriaxone-resistant isolates exceeded the threshold of 5% in 2017 (7.4% (4 of 54)) and 2020 (7.1% (3 of 42)). All retested isolates were found susceptible to ceftriaxone, azithromycin and spectinomycin, and resistant to ciprofloxacin. The majority were resistant to penicillin (83% (38 of 46)) and tetracycline (87% (40 of 46)). We detected chromosomal mutations associated with antibiotic resistance in gyrA, parC, penA, ponA, porB and mtrR genes. None of the retested isolates carried the mosaic penA gene. The high rate of resistance to penicillin and tetracycline is explained by the presence of bla TEM (94.7% (36 of 38)) and tetM (97.5% (39 of 40)). We found a high number of circulating multilocus STs. Almost half of them were new types, and one new type was among the four most predominant.

CONCLUSIONS

Our report provides a detailed dataset obtained through phenotypical and genotypical methods which will serve as a baseline for future surveillance of NG. We could not confirm the occurrence of ceftriaxone-resistant isolates. Our results highlight the importance of implementing quality-assured gonococcal antimicrobial resistance surveillance in Madagascar.

Distribution characteristics of the Legionella CRISPR-Cas system and its regulatory mechanism underpinning phenotypic function

Legionella is a common intracellular parasitic bacterium that infects humans via the respiratory tract, causing Legionnaires' disease, with fever and pneumonia as the main symptoms. The emergence of highly virulent and azithromycin-resistant Legionella pneumophila is a major challenge in clinical anti-infective therapy. The CRISPR-Cas acquired immune system provides immune defense against foreign nucleic acids and regulates strain biological functions. However, the distribution of the CRISPR-Cas system in Legionella and how it regulates gene expression in L. pneumophila remain unclear. Herein, we assessed 915 Legionella whole-genome sequences to determine the distribution characteristics of the CRISPR-Cas system and constructed gene deletion mutants to explore the regulation of the system based on growth ability in vitro, antibiotic sensitivity, and intracellular proliferation of L. pneumophila. The CRISPR-Cas system in Legionella was predominantly Type II-B and was mainly concentrated in the genome of L. pneumophila ST1 strains. The Type II-B CRISPR-Cas system showed no effect on the strain's growth ability in vitro but significantly reduced resistance to azithromycin and decreased proliferation ability due to regulation of the lpeAB efflux pump and the Dot/Icm type IV secretion system. Thus, the Type II-B CRISPR-Cas system plays a crucial role in regulating the virulence of L. pneumophila. This expands our understanding of drug resistance and pathogenicity in Legionella, provides a scientific basis for the prevention of Legionnaires' disease outbreaks and the rational use of clinical drugs, and facilitates effective treatment of Legionnaires' disease.

Azithromycin Augments Bacterial Uptake and Anti-Inflammatory Macrophage Polarization in Cystic Fibrosis

BACKGROUND

Azithromycin (AZM) is widely being used for treating patients with cystic fibrosis (pwCF) following clinical trials demonstrating improved lung function and fewer incidents of pulmonary exacerba-tions. While the precise mechanisms remain elusive, immunomodulatory actions are thought to be involved. We previously reported impaired phagocytosis and defective anti-inflammatory M2 macrophage polarization in CF. This study systematically analyzed the effect of AZM on the functions of unpolarized and M1/M2 polarized macrophages in CF.

METHODS

Monocytes, isolated from the venous blood of patients with CF (pwCF) and healthy controls (HCs), were differentiated into monocyte-derived macrophages (MDMs) and subsequently infected with P. aeruginosa. P. aeruginosa uptake and killing by MDMs in the presence or absence of AZM was studied. M1 and M2 macrophage polarizations were induced and their functions and cytokine release were analyzed.

RESULTS

Following AZM treatment, both HC and CF MDMs exhibited a significant increase in P. aeruginosa uptake and killing, however, lysosomal acidification remained unchanged. AZM treatment led to higher activation of ERK1/2 in both HC and CF MDMs. Pharmacological inhibition of ERK1/2 using U0126 significantly reduced P. aeruginosa uptake in HC MDMs. M1 macrophage polarization remained unaffected; however, AZM treatment led to increased IL-6 and IL-10 release in both HC and CF M1 macrophages. AZM also significantly increased the phagocytic index for both pHrodo E. coli and S. aureus in CF M1 macrophages. In CF, AZM treatment promoted anti-inflammatory M2 macrophage polarization, with an increased percentage of CD209+ M2 macrophages, induction of the M2 gene CCL18, along with its secretion in the culture supernatant. However, AZM d'd not restore endocytosis in CF, another essential feature of M2 macrophages.

CONCLUSIONS

This study highlights the cellular functions and molecular targets of AZM which may involve an improved uptake of both Gram-positive and Gram-negative bacteria, restored anti-inflammatory macrophage polarization in CF. This may in turn shape the reduced lung inflammation observed in clinical trials. In addition, we confirmed the role of ERK1/2 activation for bacterial uptake.

Genomic analysis of azithromycin-resistant Salmonella from food animals at slaughter and processing, and retail meats, 2011-2021, United States

IMPORTANCE

Macrolides of different ring sizes are critically important antimicrobials for human medicine and veterinary medicine, though the widely used 15-membered ring azithromycin in humans is not approved for use in veterinary medicine. We document here the emergence of azithromycin-resistant Salmonella among the NARMS culture collections between 2011 and 2021 in food animals and retail meats, some with co-resistance to ceftriaxone or decreased susceptibility to ciprofloxacin. We also provide insights into the underlying genetic mechanisms and genomic contexts, including the first report of a novel combination of azithromycin resistance determinants and the characterization of multidrug-resistant plasmids. Further, we highlight the emergence of a multidrug-resistant Salmonella Newport clone in food animals (mainly cattle) with both azithromycin resistance and decreased susceptibility to ciprofloxacin. These findings contribute to a better understating of azithromycin resistance mechanisms in Salmonella and warrant further investigations on the drivers behind the emergence of resistant clones.

A multicenter retrospective electronic health record database evaluation of subjects with Mycoplasma genitalium

BACKGROUND

Mycoplasma genitalium is a sexually transmitted infection (STI) increasing in prevalence. The recent availability of nucleic acid amplification tests (NAATs) has led to updated diagnostic and treatment guidelines. As medication therapy experts, pharmacists can facilitate appropriate antimicrobial selection and stewardship and optimize best patient-care practices in the setting of M. genitalium infection.

OBJECTIVE

This study aimed to evaluate patient demographics, therapeutic approaches, and complications of patients with laboratory evidence of M. genitalium hypothesizing that younger adolescent females are affected by this organism, receive suboptimal treatment, and have more complications than adults.

METHODS

This was a retrospective cohort study using TriNetX multicenter electronic health record data of subjects aged 12 years and older with evidence of M. genitalium DNA detected via NAATs. The cohort was divided into 2 age groups: adolescents (12-21 years) and adults (older than 21 years). We evaluated age, sex, race, ethnicity, diagnostic codes, and medication codes.

RESULTS

Our study included 1126 subjects (192 adolescents [17.1%] and 934 adults [82.9%]) who tested positive for M. genitalium. Subjects in the adolescent group had higher odds of being women (2.52 [1.80, 3.54], P < 0.001), having inflammatory diseases of female pelvic organs diagnostic codes (1.51 [1.06, 2.16], P = 0.025), increased odds of azithromycin prescription (1.70 [1.17, 2.48], P = 0.005), and decreased odds of moxifloxacin prescription (0.41 [0.26, 0.64], P < 0.001).

CONCLUSIONS

Our study revealed a higher prevalence of M. genitalium infection in adults and adolescents with increased odds of receiving azithromycin and decreased odds of receiving moxifloxacin. Both age groups had decreased odds of receiving doxycycline compared with azithromycin despite guidelines recommending initial empirical antibiotic treatment with doxycycline and growing macrolide resistance. Suboptimal treatment of this infection may lead to lifelong complications. Pharmacists may provide crucial guidance and education to both patients and health care providers regarding appropriate treatment for M. genitalium.

Microenvironment responsive charge-switchable nanoparticles act on biofilm eradication and virulence inhibition for chronic lung infection treatment

Chronic pulmonary infection caused by Pseudomonas aeruginosa (P. aeruginosa) is a common lung disease with high mortality, posing severe threats to public health. Highly resistant biofilm and intrinsic resistance make P. aeruginosa hard to eradicate, while powerful virulence system of P. aeruginosa may give rise to the recurrence of infection and eventual failure of antibiotic therapy. To address these issues, infection-microenvironment responsive nanoparticles functioning on biofilm eradication and virulence inhibition were simply prepared by electrostatic complexation between dimethylmaleic anhydride (DA) modified negatively charged coating and epsilon-poly(l-lysine) derived cationic nanoparticles loaded with azithromycin (AZI) (DA-AZI NPs). Charge reversal responsive to acidic condition enabled DA-AZI NPs to successively penetrate through both mucus and biofilms, followed by targeting to P. aeruginosa and permeabilizing its outer/inner membrane. Then in situ released AZI, which was induced by the lipase-triggered NPs dissociation, could easily enter into bacteria to take effects. DA-AZI NPs exhibited enhanced eradication activity against P. aeruginosa biofilms with a decrease of >99.999% of bacterial colonies, as well as remarkable inhibitory effects on the production of virulence factors and bacteria re-adhesion & biofilm re-formation. In a chronic pulmonary infection model, nebulization of DA-AZI NPs into infected mice resulted in prolonged retention and increased accumulation of the NPs in the infected sites of the lungs. Moreover, they significantly reduced the burden of P. aeruginosa, effectively alleviating lung tissue damages and inflammation. Overall, the proposed DA-AZI NPs highlight an innovative strategy for treating chronic pulmonary infection.

Baseline azithromycin resistance in the gut microbiota of preterm born infants

BACKGROUND

Macrolides, including azithromycin, are increasingly used in preterm-born infants to treat Ureaplasma infections. The baseline carriage of macrolide resistance genes in the preterm stool microbiota is unknown.

OBJECTIVES

Identify carriage of azithromycin resistant bacteria and the incidence of macrolide resistant genes.

METHODS

Azithromycin resistant bacteria were isolated from serial stool samples obtained from preterm infants (≤32 weeks' gestation) by culturing aerobically/anaerobically, in the presence/absence of azithromycin. Using quantitative PCR, we targeted 6 common macrolide resistance genes (erm(A), erm(B), erm(C), erm(F), mef(A/E), msr(A)) in DNA extracted from selected bacteria resistant to azithromycin.

RESULTS

From 89 stool samples from 37 preterm-born infants, 93.3% showed bacterial growth in aerobic or anaerobic conditions. From the 280 azithromycin resistant isolates that were identified, Staphylococcus (75%) and Enterococcus (15%) species dominated. Macrolide resistance genes were identified in 91% of resistant isolates: commonest were erm(C) (46% of isolates) and msr(A) (40%). Multiple macrolide resistance genes were identified in 18% of isolates.

CONCLUSION

Macrolide resistance is common in the gut microbiota of preterm-born infants early in life, most likely acquired from exposure to the maternal microbiota. It will be important to assess modulation of macrolide resistance, if macrolide treatment becomes routine in the management of preterm infants.

IMPACT STATEMENT

Azithromycin resistance is present in the stool microbiota in the first month of life in preterm infants 91% of azithromycin resistant bacteria carried at least one of 6 common macrolide resistant genes Increasing use of macrolides in the preterm population makes this an important area of study.

A Comparative Study on Antimicrobial Resistance in Escherichia coli Isolated from Channel Catfish and Related Freshwater Fish Species

Antimicrobial resistance (AMR) trends in 114 generic Escherichia coli isolated from channel catfish and related fish species were investigated in this study. Of these, 45 isolates were from commercial-sized channel catfish harvested from fishponds in Alabama, while 69 isolates were from Siluriformes products, accessed from the U.S. Department of Agriculture Food Safety and Inspection Service' (FSIS) National Antimicrobial Resistance Monitoring System (NARMS) program. Antibiotic susceptibility testing and whole genome sequencing were performed using the GenomeTrakr protocol. Upon analysis, the fishpond isolates showed resistance to ampicillin (44%), meropenem (7%) and azithromycin (4%). The FSIS NARMS isolates showed resistance to tetracycline (31.9%), chloramphenicol (20.3%), sulfisoxazole (17.4%), ampicillin (5.8%) and trimethoprim-sulfamethoxazole, nalidixic acid, amoxicillin-clavulanic acid, azithromycin and cefoxitin below 5% each. There was no correlation between genotypic and phenotypic resistance in the fishpond isolates, however, there was in NARMS isolates for folate pathway antagonists: Sulfisoxazole vs. sul1 and sul2 (p = 0.0042 and p < 0.0001, respectively) and trimethoprim-sulfamethoxazole vs. dfrA16 and sul1 (p = 0.0290 and p = 0.013, respectively). Furthermore, correlations were found for tetracyclines: Tetracycline vs. tet(A) and tet(B) (p < 0.0001 each), macrolides: Azithromycin vs. mph(E) and msr(E) (p = 0.0145 each), phenicols: Chloramphenicol vs. mdtM (p < 0.0001), quinolones: Nalidixic acid vs. gyrA_S83L=POINT (p = 0.0004), and β-lactams: Ampicillin vs. blaTEM-1 (p < 0.0001). Overall, we recorded differences in antimicrobial susceptibility testing profiles, phenotypic-genotypic concordance, and resistance to critically important antimicrobials, which may be a public health concern.

Anti-babesial activity of a series of 6,7-dimethoxyquinazoline-2,4-diamines (DMQDAs)

Diminazene aceturate (DA), imidocarb dipropionate (ID), atovaquone (ATO), azithromycin (AZI), clindamycin, and quinine have been used to treat animal and human babesiosis for many years, despite their negative effects and rising indications of resistance. Thus, finding anti-babesial compounds that can either treat the infection or lower the dose of drugs given has been a primary objective. Quinazolines are one of the most important nitrogen heterocycles, with a wide range of pharmacological activities including analgesic, anti-inflammatory, sedative-hypnotic, anti-histaminic, anti-cancer, and anti-protozoan properties. The present study investigated the anti-babesial activities of twenty 6,7-dimethoxyquinazoline-2,4-diamines on Babesia spp. One candidate, 6,7-dimethoxy-N4-ethylisopropyl-N2-ethyl(pyridin-4-yl)quinazoline-2,4-diamine (SHG02), showed potent inhibition on Babesia gibsoni in vitro, as well as on B. microti and B. rodhaini in mice. Our findings indicate that the candidate compound SHG02 is promising for further development of anti-babesial drugs and provides a new structure to be explored for developing anti-Babesia therapeutics.

Antimicrobial Resistance of Genital Mycoplasma and Ureaplasma: A Multicentre Study Over a 5-Year Period in Italy (2017-2021)

Updated data on genital Mollicutes prevalence and antimicrobial susceptibility can help provide guidance for antibiotic stewardship and set up effective strategies for infection control policies. In this multicentre study, we assessed the prevalence and the resistance profile of Mycoplasma hominis (MH) and Ureaplasma species (U. parvum/U. urealyticum), analyzing data from 21,210 subjects who provided urogenital samples for Mollicutes detection by culture over a 5-year period (2017-2021) in two high-density urban areas in the North of Italy (i.e., Bologna and Lecco). Overall prevalence of Mollicutes infection was 22.3%, with women showing a significantly higher detection rate than men (p < 0.00001). The prevalence decreased with age (highest prevalence <30 years) and over the years considered. Ureaplasma strains were much more frequently detected (62.3%) compared to MH (8.3%) and to mixed infections (29.4%). Ureaplasma species showed high levels of ciprofloxacin resistance (39.5%), whereas MH strains were nonsusceptible to azithromycin and roxithromycin in about 60% of cases. Over time, a significant decrease of resistance to azithromycin and doxycycline was detected (p < 0.0001 and 0.0004, respectively), in parallel with an important increase of ciprofloxacin-resistance levels (p < 0.0001). Overall, our results revealed that minocycline and josamycin can be first-line drugs for Mollicutes empirical treatment.

Preventive and therapeutic effects of azithromycin on acrylamide-induced neurotoxicity in rats

BACKGROUND

Acrylamide (ACR) can induce neurotoxicity through different pathways, including oxidative stress and apoptosis. Azithromycin is well-known for its antioxidant and anti-apoptotic properties.

OBJECTIVE

To evaluate the potential neuroprotective effect of azithromycin in an in vivo model of ACR-induced neurotoxicity, by investigating its impact on oxidative stress and apoptosis pathways.

METHODS

Male rats were divided into eleven groups at random (n = 6). 1:control (vehicle), 2:ACR (50 mg/kg, 11 days, I.P.), 3-7:ACR+ azithromycin (3.1, 6.25, 12.5, 25, 50 mg/kg, 11 days, I.P.), 8-9:ACR+ azithromycin (3.1, 6.25 mg/kg, from day 3-11), 10: ACR+ vitamin E (200 mg/kg, every other day, I.P.), 11. Azithromycin (50 mg/kg). Following the treatment period, a gait score examination was performed, and malondialdehyde (MDA), glutathione (GSH), Bcl-2-associated X protein (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and caspase-3 levels in the cerebral cortex were measured.

RESULTS

Gait abnormality, a drop in GSH, and an increase in lipid peroxidation, Bax/Bcl-2 ratio, and caspase-3 levels were all significantly triggered by ACR in the cerebral cortex versus the control group. Azithromycin 3.1 and 6.25 mg/kg with ACR and azithromycin 6.25 mg/kg with ACR from day 3-11 ameliorated movement disorders caused by ACR. Azithromycin in all doses and both protocols along with ACR decreased the MDA level. Azithromycin (3.1, 6.25 mg/kg) along with ACR in both protocols increased the level of GSH, reduced the Bax/Bcl-2 ratio and caspase-3 amounts in the brain tissue versus the ACR group.

CONCLUSIONS

Administration of azithromycin had both preventive and therapeutic effects on ACR-induced neurotoxicity through its antioxidant and antiapoptotic properties.

Burden of enteric fever and antibiotic sensitivity in Nepalese Children Prior to Typhoid Vaccine in National Immunization Program

BACKGROUND

Enteric fever is a major public health problem in developing and under developed countries. Case fatality rate without treatment is 10-30% and with appropriate treatment is only 1-4%. Gold standard for diagnosis is isolation of Salmonella enterica from blood or bone marrow. Antibiotics resistance is skyrocketing with emergence of multidrug resistance S. typhi and extensively drug resistant S. typhi.

METHODS

The blood culture done in Kanti children hospital in last six years were taken from the data base and the culture positive cases were taken from which the salmonella species positive cases along with the drug sensitivity pattern were used in our study.

RESULTS

The culture positivity rate was 2.8% and 7.6% (n=136) among the culture positive cases were Salmonella species. Salmonella typhi (121; 88.9%) was the most frequently isolated species, followed by Salmonella paratyphi A (13; 9.5%) and Salmonella paratyphi B (2;1.4%). Children with age 5-10 years was the most affected age group for infection with Salmonella, 50.0% (n=68). Nalidixic acid is resistant in 89.9% Salmonella typhi; followed by ciprofloxacin (31.8%), ofloxacin (18.2%), ampicillin (9.6%), azithromycin (8.4%), chloramphenicol (8.2%), cotrimoxazole (5.4%), cefixime (4%), ceftriaxone (2.5%) and cefotaxime (0.0%). Cefixime, ceftriaxone, cefotaxime are 100% sensitive to Salmonella paratyphi, followed by cotrimoxazole (92.9%), ofloxacin (81.8%), chloramphenicol (75%), azithromycin (66.7%), ampicillin (60%), ciprofloxacin (50%) and Nalidixic acid (23.1%).

CONCLUSIONS

Salmonella species culture isolatation are declining every year. Fluoroquinolones have more resistance than first line drugs of typhoid, azithromycin resistance is rising but 3rd generation cephalosporins are sensitive to Salmonella species.

Rhamnolipid Micelles Assist Azithromycin in Efficiently Disrupting Staphylococcus aureus Biofilms and Impeding Their Re-Formation

Introduction

Biofilm is highly resistant to antibiotics due to its heterogeneity and is implicated in over 80% of chronic infections; these refractory and relapse-prone infections pose a huge medical burden.

Methods

In this study, rhamnolipid (RHL), a biosurfactant with antibiofilm activity, was loaded with the antibiotic azithromycin (AZI) to construct a stable nanomicelle (AZI@RHL) that promotes Staphylococcus aureus (S. aureus) biofilm disruption.

Results

AZI@RHL micelles made a destruction in biofilms. The biofilm biomasses were reduced significantly by 48.2% (P<0.05), and the main components polysaccharides and proteins were reduced by 47.5% and 36.8%, respectively. These decreases were about 3.1 (15.9%), 7.3 (6.5%), and 1.9 (19.5%) times higher compared with those reported for free AZI. The disruption of biofilm structure was observed under a confocal microscope with fluorescent labeling, and 48.2% of the cells in the biofilm were killed. By contrast, the clearance rates of cells were only 20% and 17% when treated alone with blank micelles or free AZI. Biofilm formation was inhibited up to 92% in the AZI@RHL group due to effects on cell auto-aggregation and eDNA release. The rates for the other groups were significantly lower, with only 27.7% for the RHL group and 12% for the AZI group (P<0.05). The low cell survival and great formation inhibition could reduce biofilm recolonization and re-formation.

Conclusion

The antibiofilm efficacy of rhamnolipid was improved through micellar nanoparticle effects when loading azithromycin. AZI@RHL provides a one-step solution that covers biofilm disruption, bacteria inactivation, recolonization avoidance, and biofilm re-formation inhibition.

Antimicrobial Resistance and Molecular Typing of Neisseria gonorrhoeae Isolates From the Eastern Cape Province in South Africa

BACKGROUND

There is a paucity of Neisseria gonorrhoeae antimicrobial resistance data from resource-constrained settings because of the lack of diagnostic testing and limited scale of surveillance programs. This study aimed to determine the antimicrobial resistance profile of N. gonorrhoeae in the rural Eastern Cape province of South Africa.

METHODS

Specimens for N. gonorrhoeae culture were obtained from men with urethral discharge and women with vaginal discharge attending primary health care facilities. Direct inoculation of the agar plates was performed followed by culture and drug susceptibility testing using the Etest at the laboratory. Whole-genome sequencing of the isolates was performed to identify resistance-determining variants.

RESULTS

One hundred N. gonorrhoeae isolates were obtained. Most strains were nonsusceptible to ciprofloxacin (76%), tetracycline (75%), and penicillin G (72%). The gyrA S91F mutation was present in 68 of 72 ciprofloxacin-resistant isolates (94%), with concurrent parC mutations in 47 of 68 (69%); gyrA I250M was the only mutation in 4 other resistant strains. One azithromycin-resistant isolate was identified with a minimal inhibitory concentration (MIC) of 8.0 mg/L and the 23S rDNA gene mutation C2597T. The median MIC of cefixime was 0.016 mg/L (range, 0.016-0.064 mg/L), and that of ceftriaxone was 0.016 mg/L (range, 0.016 mg/L). Whole-genome sequencing showed 58 sequence types as revealed in N. gonorrhoeae sequence typing for antimicrobial resistance and 70 sequence types in N. gonorrhoeae multiantigen sequence typing.

CONCLUSIONS

This study confirmed high rates of N. gonorrhoeae antimicrobial resistance to ciprofloxacin, penicillin G, and tetracycline in our setting. The MICs of cephalosporins are reassuring for ceftriaxone use in syndromic treatment regimens, but the identification of azithromycin resistance warrants further attention.