| Objective:The types,levels,and distribution characteristics of antibiotic resistance genes(ARGs)associated with multidrug-resistant organism(MDRO)in the air-conditioning filter dust in hospital wards were detected in this study.It is intended to help us understand the possible contamination status of antibiotic-resistant bacteria in different hospital ward environments for a period of time.At the same time,it provides a certain reference basis for the cleaning and disinfection measures of the hospital ward environment and hospital infection management and control.Methods:In this study,two large general hospitals in Wuhan,hospitals A and B,were selected as the research object.A total of 85 samples of air-conditioning filter dust in different department wards were collected in batches according to seasons during November 2018 to November 2019.A total of 15 ARGs from 7 major classes of antibiotics were qualitatively detected by the polymerase chain reaction(PCR).Among them,9 typical ARGs and 16S r RNA genes were quantitatively detected by quantitative polymerase chain reaction(q PCR).The bacteria in the dust were cultured with tryptic soy agar(TSA)and MRSA,ESBL,m Super CARBA three selective medium and the colony forming units were counted,including total bacteria,methicillin-resistant Staphylococcus aureus(MRSA),Extended-spectrumβ-lactamases(ESBLs)bacteria and carbapenem-resistant gram-negative bacteria(CR-GNB).Results:(1)A total of 13 types of ARGs from 6 major classes of antibiotics were detected in the air-conditioning filters dust in the wards of A and B hospital.The detection rate of each ARGs(the number of positive samples/the total number of samples)from high to low is int I1(82/85),NDM-1 and mec A(73/85),aac(6’)-aph(2’’)(64/85),bla TEM(53/85),bla OXA-51 and bla IMP(52/85),erm A(43/85),bla VIM(39/85),bla CTX-M(36/85),bla SHV(31/85),Van A(30/85),bla KPC(11/85).The detection rates of ARGs in 12 departments of A and B hospitals ranged from 75%to 38%.The detection rate of ARGs in departments is as follows:cardiothoracic surgery ICU>comprehensive ICU>neurosurgery ICU>neurosurgery>cardiothoracic surgery>biliary and pancreatic surgery ICU>biliary and pancreatic surgery>neurology>cardiovascular medicine>respiratory medicine,thyroid breast surgery>nephrology.(2)The average absolute concentration of 16Sr RNA was the highest at 1.14×10~9copies/ul,followed by int I1 at 1.51×10~8copies/ul,and the average absolute concentrations of the remaining 9 ARGs were 1.17×10~5～3.39×10~6copies/ul.The absolute concentrations of 9 typical ARGs from high to low are:bla IMP>bla OXA-51>bla TEM>bla NDM-1>bla VIM>mec A>bla CTX-M>bla KPC>bla SHV.The average absolute concentrations of 9 typical ARGs in 12departments of A and B hospitals from high to low are as follows:comprehensive ICU>neurosurgery>neurosurgery ICU>cardiothoracic surgery ICU>respiratory medicine>biliary and pancreatic surgery>biliary and pancreatic surgery ICU>cardiothoracic surgery>neurology>cardiovascular medicine>thyroid and breast surgery>nephrology.(3)The relative concentration of class 1 integron-integrase gene int I1 was significantly positively correlated with the relative concentrations of multiple genes such as mec A,bla CTX-M,bla NDM-1,bla OXA-51,bla TEM,bla IMP,bla VIM(P<0.01).(4)MRSA,ESBL,m Super CARBA three multidrug resistance selective medium selected antibiotic-resistant bacteria accounted for the total bacterial range of 0.067%～4.3%,0.12%～30%,0.3%～10%.At least one of the three selective medium selects antibiotic-resistant bacteria in the dust samples of the departments.Such departments account for 65%of the total number of departments examined(55/85).The total detection rate of antibiotic-resistant bacteria in different departments(the number of positive samples/the total number of samples)from high to low is ICU(49%)>surgery(38%)>internal medicine(27%).The detection rate of antibiotic-resistant bacteria from high to low is:MRSA(45%)>ESBL(35%)>m Super CARBA(29%).(5)The total number of bacteria that can be cultured per gram of filter dust in 85 different wards of A and B hospitals ranges from 8.72×10~4to6.26×10~6CFU/g.In Hospital A,the average number of bacteria in the dust accumulation per unit area of the five different batches of dust samples ranged from264～2309 CFU/cm~2.In Hospital B,the average number of culturable bacteria per unit area in three different batches of dust samples is between 308～370 CFU/cm~2.Conclusions:(1)The presence of MRSA,ESBLs-producing bacteria,carbapenem-resistant gram-negative bacteria and related 13 ARGs from 6 major antibiotics in the air-conditioning filter dust indicates that there is immediate and past pollution of antibiotic-resistant bacteria in the relevant environment.(2)Among all the detectedβ-lactam ARGs,bla TEM pollution was the most serious.Among all the detected carbapenem ARGs,the bla NDM-1,bla IMP,and bla VIM encoding B-lactamases were the main ones.The relative concentration of class 1integron-integrase gene int I1 has a positive correlation with the relative concentrations of variousβ-lactam ARGs.(3)Hospital intensive care unit and surgery are high-risk departments contaminated by ARGs and related antibiotic-resistant bacteria. |
PDF Full Text Request