Antimicrobial and antibiofilm activity of highly soluble polypyrrole against methicillin-resistant Staphylococcus aureus.

AIMS: The purpose was to evaluate the antimicrobial activity of highly soluble polypyrrole (Hs-PPy), alone or combined with oxacillin, as well as its antibiofilm potential against methicillin-resistant Staphylococcus aureus strains. Furthermore, the in silico inhibitory mechanism in efflux pumps was also investigated. METHODS AND RESULTS: Ten clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and two reference strains were used. Antimicrobial activity was determined by broth microdilution, and the combination effect with oxacillin was evaluated by the checkerboard assay. The biofilm formation capacity of MRSA and the interference of Hs-PPy were evaluated. The inhibitory action of Hs-PPy on the efflux pump was evaluated in silico through molecular docking. Hs-PPy showed activity against the isolates, with inhibitory action between 62.5 and 125 µg ml-1 and bactericidal action at 62.5 µg ml-1, as well as synergism in association with oxacillin. The isolates ranged from moderate to strong biofilm producers, and Hs-PPy interfered with the formation of this structure, but not with mature biofilm. There was no in silico interaction with the efflux protein EmrD, the closest homolog to NorA. CONCLUSIONS: Hs-PPy interferes with biofilm formation by MRSA, has synergistic potential, and is an efflux pump inhibitor.

P-type ATPase zinc transporter Rv3270 of Mycobacterium tuberculosis enhances multi-drug efflux activity.

Metal homeostasis is maintained by the uptake, storage and efflux of metal ions that are necessary for the survival of the bacterium. Homeostasis is mostly regulated by a group of transporters categorized as ABC transporters and P-type ATPases. On the other hand, efflux pumps often play a role in drug-metal cross-resistance. Here, with the help of antibiotic sensitivity, antibiotic/dye accumulation and semi-quantitative biofilm formation assessments we report the ability of Rv3270, a P-type ATPase known for its role in combating Mn2+ and Zn2+ metal ion toxicity in Mycobacterium tuberculosis, in influencing the extrusion of multiple structurally unrelated drugs and enhancing the biofilm formation of Escherichia coli and Mycobacterium smegmatis. Overexpression of Rv3270 increased the tolerance of host cells to norfloxacin, ofloxacin, sparfloxacin, ampicillin, oxacillin, amikacin and isoniazid. A significantly lower accumulation of norfloxacin, ethidium bromide, bocillin FL and levofloxacin in cells harbouring Rv3270 as compared to host cells indicated its role in enhancing efflux activity. Although over-expression of Rv3270 did not alter the susceptibility levels of levofloxacin, rifampicin and apramycin, the presence of a sub-inhibitory concentration of Zn2+ resulted in low-level tolerance towards these drugs. Of note, the expression of Rv3270 enhanced the biofilm-forming ability of the host cells strengthening its role in antimicrobial resistance. Therefore, the study indicated that the over-expression of Rv3270 enhances the drug efflux activity of the micro-organism where zinc might facilitate drug-metal cross-resistance for some antibiotics.

Liquid chromatography-tandem mass spectrometry methods for quantification of total and free antibiotic concentrations in serum and exudate from patients with post-sternotomy deep sternal wound infection receiving negative pressure wound therapy.

BACKGROUND: Systemically administered antibiotics are thought to penetrate the wounds more effectively during negative pressure wound therapy (NPWT).To test this hypothesis total and free antibiotic concentrations were quantified in serum and wound exudate. METHODS: UHPLC-MS/MS methods were developed and validated for the determination of ceftazidime, cefepime, cefotaxime, cefuroxime, cefazolin, meropenem, oxacillin, piperacillin with tazobactam, clindamycin, ciprofloxacin, sulfamethoxazole/trimethoprim (cotrimoxazole), gentamicin, vancomycin, and linezolid. The unbound antibiotic fraction was obtained by ultrafiltration using a Millipore Microcon-30kda Centrifugal Filter Unit. Analysis was performed on a 1.7-µm Acquity UPLC BEH C18 2.1 × 100-mm column with a gradient elution. RESULTS: The validation was performed for serum, exudates and free fractions. For all matrices, requirements were met regarding linearity, precision, accuracy, limit of quantitation, and matrix effect. The coefficient of variation was in the range of 1.2-13.6%.and the recovery 87.6-115.6%, respectively. Among the 29 applications of antibiotics thus far, including vancomycin, clindamycin, ciprofloxacin, oxacillin, cefepime, cefotaxime, cotrimoxazole, and gentamicin, total and free antibiotic concentrations in serum and exudate were correlated. CONCLUSION: This method can accurately quantify the total and free concentrations of 16 antibiotics. Comparison of concentration ratios between serum and exudates allows for monitoring individual antibiotics' penetration capacity in patients receiving NPWT.

Um raro caso de vasculite leucocitoclástica induzida por oxacilina / A rare case of oxacillin-induced leukocytoclastic vasculitis

A vasculite leucocitoclástica é uma patologia cujos mecanismos estão associados ao processo de inflamação vascular. Estima-se que até 24% dos casos de vasculite estão relacionados ao uso de fármacos, sendo os antimicrobianos beta-lactâmicos um dos grupos farmacológicos comumente associados a este desfecho adverso. A oxacilina, uma penicilina semissintética, possui um anel beta-lactâmico que confere atividade biológica e está associada com maior frequência a relatos de vasculite leucocitoclástica. No entanto, casos semelhantes relacionados a esse antimicrobiano são raros, sendo identificados apenas três casos na literatura. Diante desse contexto, relatamos um quarto caso de vasculite leucocitoclástica em um homem de 56 anos, em tratamento com oxacilina, que desenvolveu a vasculite no 3º dia de uso do antimicrobiano. Além da suspensão da oxacilina, ele foi tratado com 125 mg/dia de metilprednisolona endovenosa por sete dias, seguido de 20 mg/dia de prednisona oral por quatro dias, resultan-do em remissão satisfatória das lesões cutâneas e ausência de novos desfechos adversos. Este caso corrobora a possível relação causal entre o uso de oxacilina e o desenvolvimento da vasculite leucocitoclástica, apesar de sua ocorrência ser rara. A resposta favorável às intervenções terapêuticas, incluindo a suspensão da oxacilina e o uso de corticosteroides, destaca a eficácia dessas abordagens no tratamento dessa complicação (AU).

Leukocytoclastic vasculitis is a pathology whose mechanisms are associated with the process of vascular inflammation. It is estimated that up to 24% of the cases of vasculitis are drug-related, with beta-lactam antimicrobials be-ing one of the pharmacological groups commonly associated with this adverse outcome. Oxacillin, a semisynthetic penicillin, has a beta-lactam ring that confers biological activity and is most frequently associated with reports of leukocytoclastic vasculitis. However, similar cases related to this antimicrobial are rare, with only three cases identified in the literature. Against this background, we report a fourth case of leukocytoclastic vasculitis in a 56-year-old man, on oxacillin treatment, who developed the vasculitis on the 3rd day of antimicrobial use. In addition to oxacillin suspension, he was treated with 125 mg/day of intravenous methylprednisolone for seven days, followed by 20 mg/day of oral prednisone for four days, resulting in satisfactory remission of the skin lesions and no new adverse outcomes. This case provides further evidence supporting the potential causal relationship between the use of oxacillin and the development of leukocytoclastic vasculitis, albeit a rare occurrence. The positive response to therapeutic interventions, such as oxacillin suspension and corticosteroid treatment, underscores the effectiveness of these approaches in addressing this complication (AU),

Synergistic Potential of α-Melanocyte Stimulating Hormone Based Analogues with Conventional Antibiotic against Planktonic, Biofilm-Embedded, and Systemic Infection Model of MRSA.

The repotentiation of the existing antibiotics by exploiting the combinatorial potential of antimicrobial peptides (AMPs) with them is a promising approach to address the challenges of slow antibiotic development and rising antimicrobial resistance. In the current study, we explored the ability of lead second generation Ana-peptides viz. Ana-9 and Ana-10, derived from Alpha-Melanocyte Stimulating Hormone (α-MSH), to act synergistically with different classes of conventional antibiotics against methicillin-resistant Staphylococcus aureus (MRSA). The peptides exhibited prominent synergy with ß-lactam antibiotics, namely, oxacillin, ampicillin, and cephalothin, against planktonic MRSA. Furthermore, the lead combination of Ana-9/Ana-10 with oxacillin provided synergistic activity against clinical MRSA isolates. Though the treatment of MRSA is complicated by biofilms, the lead combinations successfully inhibited biofilm formation and also demonstrated biofilm disruption potential. Encouragingly, the peptides alone and in combination were able to elicit in vivo anti-MRSA activity and reduce the bacterial load in the liver and kidney of immune-compromised mice. Importantly, the presence of Ana-peptides at sub-MIC doses slowed the resistance development against oxacillin in MRSA cells. Thus, this study highlights the synergistic activity of Ana-peptides with oxacillin advocating for the potential of Ana-peptides as an alternative therapeutic and could pave the way for the reintroduction of less potent conventional antibiotics into clinical use against MRSA infections.

Phenotypic and genomic characteristics of oxacillin-susceptible mecA-positive Staphylococcus aureus, rapid selection of high-level resistance to beta-lactams.

The aim of this study is to describe the phenotypic and genetic properties of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) isolates and their beta-lactam resistant derivatives obtained after selection with oxacillin. A collection of hospital- (HA-) and community-acquired (CA-) MRSA was screened for oxacillin susceptibility. Antibiotic susceptibility testing, population analysis profile (PAP), mecA expression analysis, and whole genome sequencing (WGS) were performed for 60 mecA-positive OS-MRSA isolates. Twelve high-level beta-lactam resistant derivatives selected during PAP were also subjected to WGS. OS-MRSA were more prevalent among CA-MRSA (49/205, 24%) than among HA-MRSA (11/575, 2%). OS-MRSA isolates belonged to twelve sequence types (ST), with a predominance of ST22-t223-SCCmec IVc and ST59-t1950-SCCmec V lineages. OS-MRSA were characterized by mecA promoter mutations at - 33 (C→T) or - 7 (G→T/A) along with PBP2a substitutions (S225R or E246G). The basal and oxacillin-induced levels of mecA expression in OS-MRSA isolates were significantly lower than those in control ST8-HA-MRSA isolates. Most of the OS-MRSA isolates were heteroresistant to oxacillin. High-level beta-lactam resistant OS-MRSA derivatives selected with oxacillin carried mutations in mecA auxiliary factors: relA (metabolism of purines), tyrS, cysS (metabolism of tRNAs), aroK, cysE (metabolism of amino acids and glycolysis). Cefoxitin-based tests demonstrated high specificity for OS-MRSA detection. The highest positive predictive values (PPV > 0.95) were observed for broth microdilution, the VITEK® 2 automatic system, and chromogenic media. Susceptibility testing of CA-MRSA requires special attention due to the high prevalence of difficult-to-detect OS-MRSA among them. Mis-prescription of beta-lactams for the treatment of OS-MRSA may lead to selection of high-level resistance and treatment failures.

Design of novel water-soluble isoxazole-based antimicrobial agents and evaluation of their cytotoxicity and acute toxicity.

Based on the readily available 3-organyl-5-(chloromethyl)isoxazoles, a number of previously unknown water-soluble conjugates of isoxazoles with thiourea, amino acids, some secondary and tertiary amines, and thioglycolic acid were synthesized. The bacteriostatic activity of aforementioned compounds has been studied against Enterococcus durans B-603, Bacillus subtilis B-407, Rhodococcus qingshengii Ac-2784D, and Escherichia coli B-1238 microorganisms (provided by All-Russian Collection of Microorganisms, VKM). The influence of the nature of the substituents in positions 3 and 5 of the isoxazole ring on the antimicrobial activity of the obtained compounds has been determined. It is found that the highest bacteriostatic effect is observed for compounds containing 4-methoxyphenyl or 5-nitrofuran-2-yl substituents in position 3 of the isoxazole ring as well as methylene group in position 5 bearing residues of l-proline or N-Ac-l-cysteine (5a-d, MIC 0.06-2.5 µg/ml). The leading compounds showed low cytotoxicity on normal human skin fibroblast cells (NAF1nor) and low acute toxicity on mice in comparison with the well-known isoxazole-containing antibiotic oxacillin.

Purine Nucleosides Interfere with c-di-AMP Levels and Act as Adjuvants To Re-Sensitize MRSA To ß-Lactam Antibiotics.

The purine-derived signaling molecules c-di-AMP and (p)ppGpp control mecA/PBP2a-mediated ß-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) raise the possibility that purine availability can control antibiotic susceptibility. Consistent with this, exogenous guanosine and xanthosine, which are fluxed through the GTP branch of purine biosynthesis, were shown to significantly reduce MRSA ß-lactam resistance. In contrast, adenosine (fluxed to ATP) significantly increased oxacillin resistance, whereas inosine (which can be fluxed to ATP and GTP via hypoxanthine) only marginally increased oxacillin susceptibility. Furthermore, mutations that interfere with de novo purine synthesis (pur operon), transport (NupG, PbuG, PbuX) and the salvage pathway (DeoD2, Hpt) increased ß-lactam resistance in MRSA strain JE2. Increased resistance of a nupG mutant was not significantly reversed by guanosine, indicating that NupG is required for guanosine transport, which is required to reduce ß-lactam resistance. Suppressor mutants resistant to oxacillin/guanosine combinations contained several purine salvage pathway mutations, including nupG and hpt. Guanosine significantly increased cell size and reduced levels of c-di-AMP, while inactivation of GdpP, the c-di-AMP phosphodiesterase negated the impact of guanosine on ß-lactam susceptibility. PBP2a expression was unaffected in nupG or deoD2 mutants, suggesting that guanosine-induced ß-lactam susceptibility may result from dysfunctional c-di-AMP-dependent osmoregulation. These data reveal the therapeutic potential of purine nucleosides, as ß-lactam adjuvants that interfere with the normal activation of c-di-AMP are required for high-level ß-lactam resistance in MRSA. IMPORTANCE The clinical burden of infections caused by antimicrobial resistant (AMR) pathogens is a leading threat to public health. Maintaining the effectiveness of existing antimicrobial drugs or finding ways to reintroduce drugs to which resistance is widespread is an important part of efforts to address the AMR crisis. Predominantly, the safest and most effective class of antibiotics are the ß-lactams, which are no longer effective against methicillin-resistant Staphylococcus aureus (MRSA). Here, we report that the purine nucleosides guanosine and xanthosine have potent activity as adjuvants that can resensitize MRSA to oxacillin and other ß-lactam antibiotics. Mechanistically, exposure of MRSA to these nucleosides significantly reduced the levels of the cyclic dinucleotide c-di-AMP, which is required for ß-lactam resistance. Drugs derived from nucleotides are widely used in the treatment of cancer and viral infections highlighting the clinical potential of using purine nucleosides to restore or enhance the therapeutic effectiveness of ß-lactams against MRSA and potentially other AMR pathogens.

Origanum vulgare essential oil and carvacrol: natural alternatives against resistant bacteria / Óleo essencial de origanum vulgare e carvacrol: alternativas naturais contra bactérias resistentes / El aceite esencial de origanum vulgare y el carvacrol: alternativos naturales contra las bacterias resistentes

Bacteria that are resistant to several antibiotics are a serious One Health problem, as new alternatives for treatment do not appear at the same speed. Thus, the aim of this work was to carry out a survey of studies involving the activity of the essential oil of O. vulgare and its isolated compound carvacrol on antibiotic-resistant bacteria. To this end, a qualitative review of the literature was carried out in the PubMed database from 2015 to 2020. Both for the essential oil and for the isolated compound, the inhibitory action extends to strains often associated with difficult-to-treat infections such as oxacillin and vancomycin-resistant Staphylococcus aureus, ß-lactamase-producing strains, carbapenemases, among others. The point that distinguishes the studies is the type of methodology used in the tests, with studies with carvacrol more directed towards mechanisms of molecular action and application in cells and animals, while those with oils are more preliminary. Although these substances have potential to control resistant bacteria, more research is needed to enable their use.

Bactérias resistentes a vários antibióticos são um grave problema para a Saúde Única, pois novas alternativas de tratamento não aparecem na mesma velocidade. Assim, o objetivo deste trabalho foi realizar um levantamento de estudos envolvendo a atividade do óleo essencial de O. vulgare e seu composto isolado, carvacrol, sobre bactérias resistentes a antibióticos. Para tanto, foi realizada uma revisão qualitativa da literatura na base de dados PubMed no período de 2015 a 2020. Tanto para o óleo essencial quanto para o composto isolado, a ação inibitória se estende a cepas frequentemente associadas a infecções de difícil tratamento como Staphylococcus aureus resistente à oxacilina e vancomicina, cepas produtoras de ß-lactamase, carbapenemases, entre outras. O ponto que diferencia os estudos é o tipo de metodologia utilizada nos testes, sendo os estudos com carvacrol mais direcionados para mecanismos de ação molecular e aplicação em células e animais, enquanto os com óleos são mais preliminares. Embora essas substâncias tenham potencial para controlar bactérias resistentes, mais pesquisas são necessárias para viabilizar seu uso.

Las bacterias resistentes a diversos antibióticos son un grave problema para la Sanidad Única, ya que las nuevas alternativas de tratamiento no aparecen a la misma velocidad. Así pues, el objetivo de este trabajo fue realizar una encuesta sobre los estudios relativos a la actividad del aceite esencial de O. vulgare y su compuesto aislado, el carvacrol, sobre las bacterias resistentes a los antibióticos. Para ello, se realizó una revisión bibliográfica cualitativa en la base de datos PubMed en el periodo comprendido entre 2015 y 2020. Tanto para el aceite esencial como para el compuesto aislado, la acción inhibidora se extiende a cepas frecuentemente asociadas a infecciones de difícil tratamiento como el Staphylococcus aureus resistente a la oxacilina y a la vancomicina, cepas productoras de ß-lactamasas, carbapenemasas, entre otras. El punto que diferencia los estudios es el tipo de metodología utilizada en las pruebas, siendo los estudios con carvacrol más dirigidos a mecanismos de acción molecular y aplicación en células y animales, mientras que los de aceites son más preliminares. Aunque estas sustancias tienen potencial para controlar las bacterias resistentes, es necesario seguir investigando para que su uso sea viable.

[Staphylococcus lugdunensis infection: report of 44 cases]. / Infección por Staphylococcus lugdunensis: descripción de 44 casos.

BACKGROUND: Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CNS) with virulence and antibiotic sensitivity characteristics which makes it more similar to Staphylococcus aureus than other CNS. AIM: To know the microbiological and clinical characteristics of S. lugdunensis isolates identified from our health sector. METHODS: A retrospective study of S. lugdunensis isolates was carried out between 2017 and 2019 in the Microbiology Service of the San Jorge University Hospital in Huesca (Spain). The clinical records of patients with S. lugdunensis isolation were reviewed, considering the following factors: age, sex, sample type, service and underlying disease. Bacterial identification was performed using MALDI-TOF VITEK MS (BioMérieux, France). The pattern of antibiotic susceptibility was studied by means of plate microdilution. RESULTS: 44 isolates of S. lugdunensis were obtained: 12 corresponded to wounds, 10 were abscesses, 8 ulcers, 7 urine samples, 4 skin smears, 2 otic exudates, and 1 vaginal exudate. Regarding the underlying disease, five patients had a tumor processes and ten had diabetes mellitus. In 17 patients there was a history of recent surgery or trauma. Most of the strains were susceptible to the antibiotics studied. Production of beta-lactamase was observed in 19 of them, two were resistant to macrolides and three to clindamycin. None of the isolates were resistant to oxacillin, gentamicin or cotrimoxazole. CONCLUSIONS: Although S. lugdunensis maintains a good sensitivity to most antibiotics, its tendency to produce abscesses and that it expresses virulence factors more similar to S. aureus than to other CNS requires a correct identification in the laboratory so that its incidence is not underestimated.

Pathogenicity and transcriptome analysis of a strain of Vibrio owensii in Fenneropenaeus merguiensis.

Vibrio is an important conditional pathogen in shrimp aquaculture. This research reported a dominant bacteria strain E1 isolated from a shrimp tank with the method of biofloc culture, which was further identified as Vibrio owensii. To understand the interaction between V. owensii and the host shrimp, we studied the pathogenicity of the V. owensii and the molecular mechanisms of the Fenneropenaeus merguiensis immunity during the Vibrio invasion. Drug susceptibility tests showed that V. owensii was resistant to antibiotics streptomycin oxacillin, tetracycline, minocycline, and aztreonam, but highly sensitive to cefazolin, cefotaxime, and ciprofloxacin, and moderately sensitive to cefotaxime, ampicillin, and piperacillin. Lethal concentration 50 (LC50) test was performed to evaluate the toxicity of V. owensii to F. merguiensis. The LC50 of V. owensii infected F. merguiensis after 24, 48, 72, 96, 120, 144 and 168 h were 1.21 × 107, 1.68 × 106, 6.36 × 105, 2.15 × 105, 7.58 × 104, 5.55 × 104 and 4.33 × 104 CFU/mL. In order to explore the molecular response mechanism of F. merguiensis infected with V. owensii, the hepatopancreas of F. merguiensis were sequenced at 24 hpi and 48 hpi, and a total 40,181 of unigenes were obtained. Through comparative transcriptomic analysis, 86 differentially expressed genes (DEGs) (including 38 up-regulated DEGs, and 48 down-regulated DEGs) and 305 DEGs (including 150 up-regulated DEGs, and 155 down-regulated DEGs) were identified at 24 hpi and 48 hpi, respectively. Annotation and classification analysis of these 391 DEGs showed that most of the DEGs were annotated to metableolic and immune pathways, which indicated that F. merguiensis responded to the invasion through the regulation of material metableolism and immune system genes during V. owensii infection. In the KEGG enrichment analysis, some pathways related to immune response were significantly influenced by V. owensii infection, including phagosome, MAPK signalling pathway and PI3K-Akt signalling pathway. In addition, some pathways related to the warburg effect were also significantly enriched after V. owensii infection, including pyruvate metableolism, glycolysis/gluconeogenesis, and citrate cycle (TAC cycle). Further analysis showed that C-type lectins and ficolin were also play important roles in the immune response of F. merguiensis against V. owensii infection. The current research preliminarily revealed the immune response of F. merguiensis to V. owensii infection at the molecular level, which provided valuable information to further understand the disease control and the interaction between shrimp and Vibrio.

Infección por Staphylococcus lugdunensis: descripción de 44 casos / Staphylococcus lugdunensis infection: report of 44 cases

INTRODUCCIÓN: Staphylococcus lugdunensis, es un estafilococo coagulasa negativa (SCN) con características de virulencia y de sensibilidad antimicrobiana que lo hacen más parecido a Staphylococcus aureus que a otros SCN. OBJETIVOS: Conocer las características clínicomicrobiológicas de los aislados de S. lugdunensis identificados en nuestra institución. MATERIAL Y MÉTODOS: Se realizó un estudio retrospectivo de los aislados de S. lugdunensis entre los años 2017 y 2019 en el Servicio de Microbiología del Hospital Universitario San Jorge de Huesca (España). Se revisaron las historias clínicas correspondientes a los pacientes con aislamiento de S. lugdunensis, considerándose las siguientes variables: edad, sexo, tipo de muestra, servicio de procedencia y enfermedad de base. La identificación bacteriana se realizó con MALDI-TOF VITEK MS (BioMérieux, Francia). Así mismo, se estudió su patrón de susceptibilidad antimicrobiana in vitro mediante microdilución en placa. RESULTADOS: Se obtuvieron 44 aislados de S. lugdunensis: 12 procedían de heridas, 10 fueron abscesos, 8 úlceras, 7 orinas, 4 frotis cutáneos, 2 exudados óticos, y 1 exudado vaginal. En relación con la enfermedad de base destacaron cinco pacientes con procesos tumorales y diez con diabetes mellitus. En 17 pacientes existían antecedentes de cirugía o traumatismo reciente. La mayoría de las cepas fueron sensibles a los antimicrobianos estudiados. En 19 de ellas se observó producción de β-lactamasa, dos fueron resistentes a macrólidos y tres a clindamicina. Todas las cepas fueron sensibles a oxacilina, gentamicina y cotrimoxazol. CONCLUSIONES: Aunque S. lugdunensis mantiene una buena sensibilidad a la mayoría de los antimicrobianos, su tendencia a producir abscesos y que exprese factores de virulencia más parecido a S. aureus que a otros SCN, hace necesaria una correcta identificación en el laboratorio con el fin de que su incidencia no quede subestimada.

BACKGROUND: Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CNS) with virulence and antibiotic sensitivity characteristics which makes it more similar to Staphylococcus aureus than other CNS. AIM: To know the microbiological and clinical characteristics of S. lugdunensis isolates identified from our health sector. METHODS: A retrospective study of S. lugdunensis isolates was carried out between 2017 and 2019 in the Microbiology Service of the San Jorge University Hospital in Huesca (Spain). The clinical records of patients with S. lugdunensis isolation were reviewed, considering the following factors: age, sex, sample type, service and underlying disease. Bacterial identification was performed using MALDI-TOF VITEK MS (BioMérieux, France). The pattern of antibiotic susceptibility was studied by means of plate microdilution. RESULTS: 44 isolates of S. lugdunensis were obtained: 12 corresponded to wounds, 10 were abscesses, 8 ulcers, 7 urine samples, 4 skin smears, 2 otic exudates, and 1 vaginal exudate. Regarding the underlying disease, five patients had a tumor processes and ten had diabetes mellitus. In 17 patients there was a history of recent surgery or trauma. Most of the strains were susceptible to the antibiotics studied. Production of beta-lactamase was observed in 19 of them, two were resistant to macrolides and three to clindamycin. None of the isolates were resistant to oxacillin, gentamicin or cotrimoxazole. CONCLUSIONS: Although S. lugdunensis maintains a good sensitivity to most antibiotics, its tendency to produce abscesses and that it expresses virulence factors more similar to S. aureus than to other CNS requires a correct identification in the laboratory so that its incidence is not underestimated.

Oxacillin plus ertapenem rapidly clears persistent left ventricular assist device-related methicillin-susceptible Staphylococcus aureus bacteremia.

There is an increasing use of left ventricular assist devices (LVADs) as bridge to transplantation or permanent destination therapy in the heart failure patient population. Infection remains a common complication in LVADs, with Gram-positive skin flora as predominant pathogens implicated, including Staphylococcus aureus. While there is emerging evidence for synergistic antibiotic combinations with methicillin resistant S. aureus, there remains a significant gap in the literature for persistent methicillin susceptible S. aureus bacteremia. In this article, we describe the first successful treatment of persistent LVAD-related bacteremia with salvage oxacillin plus ertapenem. The salvage therapy described here must be balanced by the risks for toxicity, impact on resistance, microbiota disruption, drug shortages, and patient costs. This combination warrants further evaluation in the clinical setting to better establish its role in our expanding patient population.

Evaluation of different phenotypic methods to detect methicillin resistance in Staphylococcus aureus isolates recovered from cystic fibrosis patients.

Methicillin-resistant Staphylococcus aureus (MRSA) detection in cystic fibrosis (CF) is challenging. We compared different phenotypic methods among 157 S. aureus from 136 CF-patients: cefoxitin (FOX) and oxacillin (OXA) broth-microdilution; MicroScan-WalkAway®; FOX and OXA disk-diffusion (DD), and PBP2a-latex agglutination. PCR detection of mecA/mecC was the gold standard. Growth on ChromIDTM-MRSA agar was evaluated and compared with that of 157 blood culture (BC) isolates. ChromIDTM-MRSA was also tested on sputa from 111 CF-patients. 32 isolates (20%) were mecA-positive. Both FOX DD and MicroScan-WalkAway® (FOX/OXA) showed the highest sensitivity and specificity (100% and 100%, 96.9% and 99.2%, 96.9% and 100%). ChromIDTM-MRSA showed an excellent sensitivity for BC and CF-isolates (100% and 96.9%) but a poorer specificity for CF ones (95.5% vs. 73.7%), which was also observed when samples were seeded on this medium. FOX DD and MicroScan-WalkAway® are suitable for MRSA detection among CF-isolates and should be used to confirm ChromIDTM-MRSA positive CF-cultures.

Elimination of oxacillin, its toxicity and antibacterial activity by using ionizing radiation.

The chemical changes caused by electron beam and γ irradiations and the biochemical characteristics of degradation products of a frequently used antibiotic oxacillin were investigated and compared with those of cloxacillin by applying pulse radiolysis, chemical and biochemical oxygen demand, total organic carbon content, oxygen uptake rate, toxicity and antibacterial activity measurements. Oxacillin was found to be non-toxic, but poorly biodegradable by the mixed microbial population of the activated sludge of a wastewater treatment plant. Therefore, it can significantly contribute to the spread of ß-lactam antibiotic resistant bacteria. However, the products formed by γ-irradiation were more easily biodegradable as they were utilized as nutrient source by the microbes of the activated sludge and the products did not show antibacterial activity. During irradiation treatment of aerated aqueous solutions mainly hydroxyl radicals induce the elimination of antimicrobial activity by making alterations at the bicyclic ß-lactam part of these antibiotics. Since the ß-lactam part is the same in oxacillin and cloxacillin, the biochemical characteristics of products of the two antibiotics are similar. The attack of hydrated electron takes place on the carbonyl groups. When the irradiation is made under anoxic conditions these reactions may also contribute considerably to alterations at the ß-lactam part and thereby to the loss of antibacterial activity.

Infecção primária da corrente sanguínea associada ao cateter venoso central em neonatos / Infección primaria del torrente sanguíneo asociada al catéter venoso central en neonatos resumen / Central venous catheter-associated primary bloodstream infection in neonates

RESUMO Objetivo: analisar a infecção primária da corrente sanguínea associada ao cateter venoso central em neonatos internados em unidades de terapia intensiva. Método: tratou-se de um estudo ecológico realizado em 2017 a partir de notificações de infecção primária da corrente sanguínea associada ao cateter venoso central ocorridas na capital de um estado da região Centro-Oeste do Brasil. Os dados foram coletados por meio de um formulário a partir de dois bancos de dados, municipal (2012 a 2016) e nacional (2014 a 2016). Resultados: a tendência temporal da densidade de incidência de infecção foi decrescente (p=0,019), com taxa de utilização de cateter venoso central de 45%. Os patógenos mais frequentes foram Klebsiella pneumoniae, Staphylococcus coagulase negativo e Enterobacter spp. Aumento de resistência às cefalosporinas e à oxacilina ocorreu para bactérias Gram-negativo e Gram-positivo, respectivamente. Conclusão: Conclui-se que houve uma redução na taxa de IPCS associada ao cateter em neonatos no período avaliado e os episódios infecciosos foram predominantemente causados por bactérias Gram-negativo, incluindo isolados multirresistentes aos antimicrobianos. Esses achados apontam para a importância e necessidade de estratégias educacionais para a equipe multiprofissional sobre vigilância de infecção, medidas preventivas e uso racional de antimicrobianos.

Resumen: Objetivo: analizar la infección primaria del torrente sanguíneo asociada al catéter venoso central en neonatos ingresados en unidades de cuidados intensivos. Método: se trató de un estudio ecológico, realizado en 2017, a partir de notificaciones de infección primaria del torrente sanguíneo asociada al catéter venoso central, ocurridas en la capital de un estado de la región Centro-Oeste de Brasil. Los datos fueron recogidos por medio de un formulario de dos bases de datos, municipal (2012 a 2016) y nacional (2014 a 2016). Resultados: la tendencia temporal de la densidad de incidencia de infección fue decreciente (p=0,019), con tasa de utilización de catéter venoso central del 45%. Los patógenos más frecuentes fueron Klebsiella pneumoniae, Staphylococcus coagulase negativa y Enterobacter spp. Aumento de resistencia a las cefalosporinas y a la oxacilina ocurrió para bacterias Gramnegativas y Grampositivas, respectivamente. Conclusión: hubo una reducción en la tasa de infección primaria del torrente sanguíneo asociada al catéter en neonatos en el período evaluado, y los episodios infecciosos fueron predominantemente causados por bacterias gramnegativas, incluyendo aislados multirresistentes a los antimicrobianos. Estos hallazgos señalan la importancia y necesidad de estrategias educativas para el equipo multiprofesional sobre vigilancia de infecciones, medidas preventivas y uso racional de antimicrobianos.

ABSTRACT Objective: to analyze primary bloodstream infections associated with central venous catheter in neonates admitted to intensive care units. Method: ecological study, conducted in 2017, from reports of primary bloodstream infections associated with central venous catheter, which occurred in the capital of a state in the Midwest region of Brazil. Data were collected using a form from two databases, municipal (2012 to 2016) and national (2014 to 2016). Results: the temporal trend of the infection incidence density was decreasing (p=0.019), with a central venous catheter use rate of 45%. The most frequent pathogens were Klebsiella pneumoniae, Coagulase-negative staphylococci, and Enterobacter spp. Increased resistance to cephalosporins and oxacillin occurred for Gram-negative and Gram-positive bacteria, respectively. Conclusion: There was a reduction in the rate of catheter-associated primary bloodstream infection in neonates in the period evaluated, and the infectious episodes were predominantly caused by Gram-negative bacteria, including antimicrobial multi-resistant isolates. These findings point to the importance and need for educational strategies for the multiprofessional team on infection surveillance, preventive measures, and rational use of antimicrobials.

Piomiositis, artritis séptica y osteomielitis aguda porStaphylococcus aureus meticilino resistente de la comunidad enpaciente pediátrico / Pyomyositis, septic arthritis and acute osteomyelitis due tocommunity methicillin-resistant Staphylococcus aureus in apediatric patient

Las infecciones osteoarticulares y musculoesqueléticas son patologías infecciosas relativamente infrecuentes en la infancia, afectando generalmente a varones y menores de 5 años. Países desarrollados reportan una incidencia anual de osteomielitis de 10 a 80/100.000 niños y de 4 casos/100.000 niños para artritis séptica. En países tropicales, la piomiositis tiene una incidencia de un caso por cada 2.000 habitantes. El Staphylococcus aureus es el principal agente causal. En la infancia la vía más común del legada del germen a la articulación es la hematógena. Hasta en un 30% de niños coexisten osteomielitis aguda y artritis séptica. Se presenta el caso de preescolar masculino de 3años, quien posterior a aplastamiento de miembro inferior izquierdo, presenta aumento de volumen, dolor y limitación para la marcha, asociándose 9 días después fiebre de 39.5°C,acudiendo al Hospital Universitario de Caracas. La anamnesis, evaluación clínica y estudios paraclínicos fueron sugestivos depiomiositis de muslo izquierdo, osteomielitis de fémur izquierdo y artritis séptica de rodilla izquierda. Se indica antibioticoterapiacon cobertura para Staphylococcus aureus (ciprofloxacina y clindamicina). Se realizó artrotomía evacuadora y limpieza quirúrgica de estructuras afectadas. El cultivo reportó Staphylococcus aureus sensible a ciprofloxacina, gentamicina, linezolid, rifampicina, trimetropin/sulfametoxazol; resistentea clindamicina, eritromicina, oxacilina, por lo que se omitióclindamicina y se indicó trimetropin/sulfametoxazol. Cumplió21 días de tratamiento intravenoso, observándose evolución satisfactoria por lo que se decidió egreso, dando continuidad con tratamiento vía oral por cuatro semanas y seguimiento interdisciplinario. El abordaje oportuno y adecuado de estas patologías disminuye el riesgo de desarrollar complicaciones(AU)

Osteoarticular and musculoskeletal infections are relatively rare infectious diseases in childhood, generally affecting men and children under 5 years of age. Developed countries report an annual incidence of osteomyelitis of 10 to 80 / 100,000 children and 4 cases / 100,000 children for septicarthritis. In tropical countries, pyomyositis has an incidence of one case for every 2,000 inhabitants. Staphylococcus aureusis the main causative agent. In childhood the most commonroute of arrival of the germ to the joint is hematogenous.Up to 30% of children coexist acute osteomyelitis and septic arthritis. We present the case of a 3-year-old male preschoolerwho, after crushing his left lower limb, presented an increasein volume, pain, and limited gait, and was associated witha fever of 39.5 ° C 9 days later, going to the University Hospital of Caracas. the anamnesis, clinical evaluation and paraclinical studies were suggestive of pyomyositis of the leftthigh, osteomyelitis of the left femur and septic arthritis of the left knee. Antibiotic therapy with coverage for Staphylococcus aureus (ciprofloxacin and clindamycin) is indicated. Evacuating arthrotomy and surgical cleaning of affected structures were performed. The culture reported Staphylococcus aureus sensitiveto ciprofloxacin, gentamicin, linezolid, rifampin, trimetropin /sulfamethoxazole; resistant to clindamycin, erythromycin,oxacillin, therefore clindamycin was omitted and trimetropin /sulfamethoxazole was indicated. He completed 21 days ofintravenous treatment, observing satisfactory evolution so hisdis charge was decided, continuing with oral treatment for four weeks and interdisciplinary follow-up. The timely and adequate approach to these pathologies reduces the risk of developing complications(AU)

Novel N-Substituted 3-Aryl-4-(diethoxyphosphoryl)azetidin-2-ones as Antibiotic Enhancers and Antiviral Agents in Search for a Successful Treatment of Complex Infections.

A novel series of N-substituted cis- and trans-3-aryl-4-(diethoxyphosphoryl)azetidin-2-ones were synthesized by the Kinugasa reaction of N-methyl- or N-benzyl-(diethyoxyphosphoryl)nitrone and selected aryl alkynes. Stereochemistry of diastereoisomeric adducts was established based on vicinal H3-H4 coupling constants in azetidin-2-one ring. All the obtained azetidin-2-ones were evaluated for the antiviral activity against a broad range of DNA and RNA viruses. Azetidin-2-one trans-11f showed moderate inhibitory activity against human coronavirus (229E) with EC50 = 45 µM. The other isomer cis-11f was active against influenza A virus H1N1 subtype (EC50 = 12 µM by visual CPE score; EC50 = 8.3 µM by TMS score; MCC > 100 µM, CC50 = 39.9 µM). Several azetidin-2-ones 10 and 11 were tested for their cytostatic activity toward nine cancerous cell lines and several of them appeared slightly active for Capan-1, Hap1 and HCT-116 cells values of IC50 in the range 14.5-97.9 µM. Compound trans-11f was identified as adjuvant of oxacillin with significant ability to enhance the efficacy of this antibiotic toward the highly resistant S. aureus strain HEMSA 5. Docking and molecular dynamics simulations showed that enantiomer (3R,4S)-11f can be responsible for the promising activity due to the potency in displacing oxacillin at ß-lactamase, thus protecting the antibiotic from undesirable biotransformation.

Antimicrobial activity of dalbavancin and comparators against Staphylococcus aureus causing pneumonia in patients with and without cystic fibrosis.

The activities of dalbavancin and comparator agents were evaluated against Staphylococcus aureus isolated from the lower respiratory tract of cystic fibrosis (CF) and non-CF patients with pneumonia. Bacterial isolates (n = 357) were collected from CF patients in 36 medical centers worldwide (2018-2019) and susceptibility tested using reference broth microdilution. Susceptibility results from these isolates were compared with those for 725 S. aureus isolates consecutively collected from non-CF patients with pneumonia from the same medical centers over the same period. Only isolates determined to be the probable cause of pneumonia were included in the study. Susceptibility profiles were very similar among isolates from CF and non-CF patients. Dalbavancin exhibited potent activity (MIC50/90, 0.03/0.03 mg/L) and complete coverage (100.0% susceptibility) against isolates from CF and non-CF patients. Ceftaroline (MIC50/90, 0.25/1 mg/L) was active against 97.8% and 98.1% of isolates from CF and non-CF patients, respectively. Oxacillin resistance (MRSA) rates were 27.7% among CF and 28.7% among non-CF patients. Among MRSA isolates from CF/non-CF patients (n = 99/208), susceptibility to ceftaroline, clindamycin, levofloxacin, and tetracycline were 91.9%/93.3%, 58.6%/64.4%, 40.4%/29.3%, and 83.8%/89.4%, respectively. Dalbavancin demonstrated high potency against S. aureus from CF and non-CF patients and may represent a valuable treatment option for CF patients with MRSA pulmonary infection.

Tercer caso de vasculitis leucocitoclástica cutánea secundaria al uso de oxacilina: reporte de caso / Third case in the literature of cutaneous leukocytoclastic vasculitis secondary to oxacilin use

Resumen La vasculitis leucocitoclastica es una patologìa que compromete los vasos pequeños y cuya causa predominantemente se ha descrito como idiopatica. Se presenta el caso de una mujer de 78 años hipertensa, diabética y con enfermedad renal crónica en estadio 5, que presentó lesiones limitadas a la piel posterior a la administración de oxacilina para manejo de bacteremia por SAMS. La presentación clínica se basó en purpuras palpables predominantemente en miembros inferiores y lesiones dolorosas coalescentes que formaban ampollas de contenido hemorrágico. Estas lesiones resolvieron gradualmente después del cambio de la terapia mencionada anteriormente. La biopsia fue compatible con vasculitis leucocitoclástica, con paraclínicos que descartaron causas infecciosas y autoinmunes.

Abstract Leukocytoclastic vasculitis is a pathology that involves small vessels and whose cause has been predominantly described as idiopathic. The clinical case of a 78-year-old woman with hypertension, diabetic and chronic stage 5 kidney disease, who presented limited skin lesions after administration of oxacillin for management of bacteremia by MSSA. The clinical presentation consisted on palpable purpura predominantly in the lower limbs and painful coalescent lesions that formed blisters of hemorrhagic content. Lesions gradually resolved after the change of the therapy mentioned above. The biopsy was compatible with leukocytocastic vasculitis, with paraclinics who ruled out infectious and autoimmune causes.