Epidemiology and in vitro antimicrobial susceptibility of aerobic Actinomycetales in a clinical setting

IntroductionThe incidence of infections caused by aerobic actinomycetes is increasing. Recent changes in taxonomy and the variability in susceptibility patterns among species make necessary a proper identification and antibiotic susceptibility testing.Material and methodsFifty-three strains of aerobic actinomycetes were identified by MALDI-TOF MS using the VITEK MS Mycobacterium/Nocardia kit (bioMérieux, France) in a tertiary hospital in Spain during a six-year period. Antimicrobial susceptibility testing of the isolates was performed using the Sensititre Rapmycoi microdilution panel (Thermo Fisher Scientific, Massachusetts, USA).ResultsForty strains of Nocardia spp. were identified in the study, being N. farcinica and N. cyriacigeorgica the most prevalent ones. All isolates were susceptible to linezolid and the resistance to amikacin was only observed in one isolate of Gordonia sputi. Resistance to cotrimoxazole was only found in five isolates.ConclusionsRoutine identification and antimicrobial susceptibility testing of aerobic actinomycetes is advisable for an efficient identification of species and effective treatment.     

Case report of cutaneous nodule caused by Gordonia bronchialis in an immunocompetent patient after receiving acupuncture

Gordonia species were recently found to cause human infection. Most Gordonia bronchialis infections are associated with sternal wounds and foreign bodies. Here, we present a case of a firm cutaneous nodule caused by G. bronchialis on an immunocompetent patient's lower extremity after receiving acupuncture. Our present case indicates that spontaneous cutaneous infection of G. bronchialis can develop even in a healthy patient. With the popularity of complementary and alternative medicine, physicians should be aware that G. bronchialis infection can be associated with Oriental medicine similar to mycobacterial infection. Recognizing the diverse clinical features of newly emerging Gordonia species will facilitate appropriate diagnosis and management of future patients.     

An insight into the ecology,diversity and adaptations of Gordonia species

The bacterial genus Gordonia encompasses a variety of versatile species that have been isolated from a multitude of environments. Gordonia was described as a genus about 20 years ago, and to date, 39 different species have been identified. Gordonia is recognized for symbiotic associations with multiple hosts, including aquatic (marine and fresh water) biological forms and terrestrial invertebrates. Some Gordonia species isolated from clinical specimens are known to be opportunistic human pathogens causing secondary infections in immunocompromised and immunosuppressive individuals. They are also predominant in mangrove ecosystems and terrestrial sites. Members of the genus Gordonia are ecologically adaptable and show marked variations in their properties and products. They generate diverse bioactive compounds and produce a variety of extracellular enzymes. In addition, production of surface active compounds and carotenoid pigments allows this group of microorganisms to grow under different conditions. Several isolates from water and soil have been implicated in bioremediation of different environments and plant associated species have been explored for agricultural applications. This review highlights the prevalence of the members of this versatile genus in diverse environments, details its associations with living forms, summarizes the biotechnologically relevant products that can be obtained and discusses the salient genomic features that allow this Actinomycete to survive in different ecological niches.     

Gordonia terrae kidney graft abscess in a renal transplant patient

We present the first report, to our knowledge, of a renal abscess cause by an infection from Gordonia terrae in a kidney transplant patient. The patient simultaneously had pulmonary tuberculosis and a perirenal allograft abscess caused by G. terrae. After treatment with imipenem, in addition to anti‐tuberculous drugs, the patient was cured.     

Analysis of desferrioxamine-like siderophores and their capability to selectively bind metals and metalloids: development of a robust analytical RP-HPLC method

The Actinobacterium Gordonia rubripertincta CWB2 (DSM 46758) produces hydroxamate-type siderophores (188 mg L⁻¹) under iron limitation. Analytical reversed-phase HPLC allowed determining a single peak of ferric iron chelating compounds from culture broth which was confirmed by the Fe-CAS assay. Elution profile and its absorbance spectrum were similar to those of commercial (des)ferrioxamine B which was used as reference compound. This confirms previously made assumptions and shows for the first time that the genus Gordonia produces desferrioxamine-like siderophores. The reversed-phase HPLC protocol was optimized to separate metal-free and -loaded oxamines. This allowed to determine siderophore concentrations in solutions as well as metal affinity. The metal loading of oxamines was confirmed by ICP-MS. As a result, it was demonstrated that desferrioxamine prefers trivalent metal ions (Fe³⁺ > Ga³⁺ > V³⁺ > Al³⁺) over divalent ones. In addition, we aimed to show the applicability of the newly established reversed-phase HPLC protocol and to increase the re-usability of desferrioxamines as metal chelators by immobilization on mesocellular silica foam carriers. The siderophores obtained from strain CWB2 and commercial desferrioxamine B were successfully linked to the carrier with a high yield (up to 95%) which was verified by the HPLC method. Metal binding studies demonstrated that metals can be bound to non-immobilized and to the covalently linked desferrioxamines, but also to the carrier material itself. The latter was found to be unspecific and, therefore, the effect of the carrier material remains a field of future research. By means of a reversed CAS assay for various elements (Nd, Gd, La, Er, Al, Ga, V, Au, Fe, As) it was possible to demonstrate improved Ga³⁺- and Nd³⁺-binding to desferrioxamine loaded mesoporous silica carriers. The combination of the robust reversed-phase HPLC method and various CAS assays provides new avenues to screen for siderophore producing strains, and to control purification and immobilization of siderophores.     

Rapid quantification and analysis of genetic diversity among Gordonia populations in foaming activated sludge plants

Activated sludge plants, sporadically suffers malfunction due to the proliferation of filamentous bacteria mainly Gordonia and Microthrix species. Nested Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (nested PCR-RFLP) in combination with quantitative real-time PCR (q PCR) was applied to study the distribution of Gordonia in foaming samples. Samples of mixed liquor were collected from three full-scale activated sludge plants that were experiencing filamentous biological foaming. Partial sequencing of 16S rRNA genes revealed the dominance of Gordonia amarae (60-80%), Gordonia terrae (10%), Gordonia polyisoprenivorans (30-40%) and an unidentified Gordonia species (20-50%). Restriction enzyme analysis of the amplicons exhibited 87.14 to 99.6% similarity at interspecies level. The q PCR results showed that there was an average of 15.6% Gordonia 16S rRNA copies with respect to the total bacterial 16S rRNA gene in foaming sludge samples with the highest being 23.51% and lowest being 10.28%. The presence of Gordonia spp. in the foaming samples was observed throughout the year but was lower during winter and its presence was significantly higher in foaming samples, compared to Microthrix parvicella (r = 0.007, P < 5%). This approach could help to quantify and confirm the existence of genetically diverse indigenous Gordonia spp. in foaming samples and can be used as an indicator of forthcoming foaming incidents.     

1例痰液戈登菌致血流感染误诊中毒性红斑病例分析

目的 通过对1例痰液戈登菌致血流感染误诊为中毒性红斑病例的回顾性分析,为微生物室工作人员和临床医生提供诊疗经验.方法 患者入院后进行痰培养和血培养,血培养有细菌生长,根据血培养结果改用美罗培南联合阿米卡星抗感染治疗.血培养分离菌用杭州滨河微量生化管,梅里埃VITEK2的NH试条,梅里埃VITEK MS和16SrRNA基...