Analysis Of Clinical Features And Drug Resistance Of Nocardia Infection In Ningxia

Objective The purpose of this study was to analyze the clinical features and drug resistance of Nocardia infection,and to study its possible mechanism of drug resistance,so as to provide a theoretical basis for clinical rational use of antibiotics.Methods The Nocardia strains were cultured at the Center of Medical Laboratory in Ningxia Medical University from January 2013 to November 2017.Analysis of strains distribution,specimen origin,clinical manifestations,drug susceptibility results and related drug resistance.Identification of species using MALDI-TOF-MS and confirmed by 16 Sr RNA gene sequencing.The susceptibility of 14 antibiotics were tested by microbroth dilution method,and the quinolone antibiotic resistance-related genes gyr A,par C,qnr A,qnr B,qnr S.Clarithromycin resistance-related genes erm A,erm B,mef A,msr D.And the tetracycline resistance related genes tet O,tet M,tet L were detected.To study its possible drug resistance mechanism preliminary.Conclusions 1.Nocardia in our hospital is mainly isolated from sputum.The most common species is N.cyriacigeorigicain.The most common site of Nocardia infection is the lungs.It can also cause central nervous system,skin and dissemination infection,The clinical manifestations are not specific.Nocardia has high sensitivity to linezolid,macrolides and other antibiotics drugs and TMP-SMX,but it is less sensitive to quinolones,and drug testing should be strengthened to provide rational clinical use of antibiotics.Results From January 2013 to November 2017,19 cases of Nocardia infection were collected.There were 12 male patients and 7 female patients.The average age was 51 years old.In the positive specimens,the most common specimens was sputum,accounting for 52.6%.The majority of the strains grew colonies that were visible to the naked eye after 72 hours of culture.The weak acid-fast stains were positive and the microscopic branches were right-angled.MALDI-TOF-MS and16 Sr RNA gene sequencing methods can identify Nocardia to species accurately.The 19 Nocardia strains contained a total of three strains,namely N.cyriacigeorigica,N.farcinica and N.otitidiscaviarum,each accounting for 63.2%,21.1%,and 15.7%.The most common site of Nocardia infection was the lungs.There were 14 cases in total.The main manifestations were fever,cough,sputum,and chest pain.3 cases were skin infections,which showed local soft tissue abscess and pain.1 case was central nervous system infection.Mainly manifested as headache,nausea,and fever.The rest were disseminated infection and dialysis-related infection,the clinical manifestations were lack of characteristic also.Drug susceptibility results showed that the resistance rate of Nocardia to ciprofloxacin was the highest,being 78.9%,followed by gentamicin,which was21.1%.All strains were sensitive to amikacin,clarithromycin,linezolid and sulfamethoxazole/trimethopri,and also showed high sensitivity to imipenem,minocycline and other drugs.Among the 19 Nocardia strains,the detection rates of fluoroquinolone-resistant genes gyr A,par C,qnr A,and qnr B were 15.8%,31.6%,21.1% and 15.8% respectively,and the qnr S gene was not detected.The detection rate of clarithromycin resistance-related gene erm A was 15.8%(3/19).Theerm B,mef A,msr D genes were not detected.The tetracycline resistance related genes tet O,tet M,tet L were not detected.2.The antibiotic resistance to fluoroquinoloneof Nocardia is serious in ourhospital,and the mechanism of fluoroquinolone resistance are likely to associate with gyr A,par C,qnr A and qnr B genes.The gene of erm A play any role in resistance of clarithromycin.The genes of tet O? tet M and tet L do not contribute to the drug resistant mechanisms of tetracycline for Nocardia,may have other resistant genes.