Achromobacter xylosoxidans NS12的分离和对硝基苯酚的降解

通过富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Achromobacter xylosoxidansNS12在好氧条件下可耐受小于1.8 mmol/L的邻硝基苯酚(ONP)或3.0 mmol/L的对硝基苯酚(PNP),能以PNP和ONP作为唯一碳源、能源和氮源生长并将其完全矿化,但该菌不能利用间硝基苯酚(MNP)作为唯一碳源和氮源生长.研究发现A.xylosoxidansNS12在降解PNP和ONP组成的混合底物时,PNP的存在可抑制ONP的降解,同时ONP的存在也抑制PNP的降解.此外,在利用PNP和ONP的混合底物时,NS12转化PNP的速率显著地高于转化ONP的速率.红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.

Characterization of two Achromobacter xylosoxidans isolates from patients with pertussis-like symptoms

Objective:To characterize two Achromobaeter xylosoxidans recovered from 2 patients diagnosed with pertussis during a Bordetella pertussis surveillance program.Methods:Nasopharyngeal swabs from 2 children under 1 year of age with clinical suspicion of pertussis were analyzed by culture and PCR.Results:Two Achromobaeter xylosoxidans A8,closely related to Bordetella spp.were recovered from 2 patients diagnosed of pertussis,both carrying the ptxA gene and IS418 the pertussis toxin encoding gene.Subsequently,antibiotic susceptibility was evaluated by disk-diffusion method and by PCR.Conclusions:Although more detailed studies are needed,the present data highlight the possibility that Achromobaeter xylosoxidans.closely related Bordetella pertussis microorganisms and not covered under the vaccine umbrella,might also result in cases of whooping cough.Thereby further surveillance is necessary to determine the extension and relevance of their pathogenic role in order to discriminate their real public health implication.

Azithromycin Exerts Bactericidal Activity and Enhances Innate Immune Mediated Killing of MDR Achromobacter xylosoxidans

Azithromycin(AZM),the most commonly prescribed antibiotic in the United States,is thought to have no activity against multidrugresistant Gram-negative pathogens such as Achromobacter xylosoxidans(AX)per standard minimum inhibitory concentration testing in cation-adjusted Mueller Hinton Broth.Here we provide the first report of AZM bactericidal activity against carbapenemresistant isolates of AX,with a multifold decrease in minimum inhibitory concentration across 12 clinical isolates when examined under physiologic testing conditions that better recapitulate the in vivo human environment.This pharmaceutical activity,evident in eukaryotic tissue culture media,is associated with enhanced AZM intracellular penetration and synergistic killing with human whole blood,serum,and neutrophils.Additionally,AZM monotherapy inhibited preformed AX biofilm growth in a dose-dependent manner together with a reduction in viable bacteria.In an illustrative case,AZM in combination with piperacillin-tazobactam exerted clear therapeutic effects in a patient with carbapenem-resistant AX mediastinitis,sternal osteomyelitis,and aortic graft infection.Our study reinforces how current antimicrobial testing practices fail to recapitulate the host environment or host-pathogen interactions and may misleadingly declare complete resistance to useful agents,adversely affecting patient outcomes.We conclude that AZM merits further exploration in the treatment of drug-resistant AX infections.Novel approaches to antimicrobial susceptibility testing that better recapitulate the host environment should be considered,especially as infections caused by multidrug-resistant Gram-negative bacterial pathogens are expanding globally with high morbidity and mortality.

高效长链烷烃降解菌ZKNU01的选育及其降解特性

通过富集分离筛选出1株高效长链烷烃降解菌,采用形态学、生理生化试验、16S r DNA序列比对和BBL Crystal AutoReaders进行菌种鉴定,并通过UV和GC-MS检测菌株对长链烷烃的降解特性。结果表明,分离到的1株长链烷降解烃菌,经鉴定为Achromobacter xylosoxidans ZKNU01。该菌能高效降解长链烷烃C15~C32,生长温度范围0~45℃,最适生长温度37℃,在接种量为106 CFU·m L^(-1),原油质量浓度为0.5 kg·L^(-1),振荡培养7 d时,降解率可达82.06%。石油中长链烷烃C15~C32以单末端氧化方式被完全降解。