Objective To explore the distribution and antimicrobial resistance of pathogens causing lower respiratory tract infection in patients, and provide basis for rational choice of antimicrobial agents in clinic.Methods All bronchoalveolar lavage fluid specimens in a hospital from January 1, 2013 to December 31, 2014 were performed culture, antimicrobial susceptibility testing of isolated strains was performed with Kirby-Bauer method.Results A total of 999 strains were isolated from 7 702 bronchoalveolar lavage fluid specimens, 398 (5.17%), 326 (4.23%), and 275(3.57%) strains were bacteria, fungus, and Mycobacterium respectively.The main bacteria were Pseudomonas aeruginosa(P.aeruginosa, n=97), Acinetobacter baumannii(A.baumannii, n=87), Klebsiella pneumoniae(K.pneumoniae, n=62), Staphylococcus aureus(S.aureus, n=44), and Haemophilus influenzae (n=28);the main fungi were Candida albicans (n=161), Aspergillus fumigatus (n=41), and Aspergillus flavus(n=38);the main Mycobacterium were Mycobacterium tuberculosis(n=271).Antimicrobial susceptibility testing results showed that resistance rates of P.aeruginosa to the commonly used antimicrobial agents (except ticarcillin/clavulanic acid and levofloxacin) were all<30.00%.Resistance rates of A.baumannii to ampicillin/sulbactam, imipenem, amikacin, gentamicin, and tobramycin were all >80.00%, but to the other commonly used antimicrobial agents were 36.84%-60.53%.Among 62 strains of K.pneumoniae, 20 were extended-spectrum β-lactamases(ESBLs)-producing strains.Antimicrobial resistance rates of ESBLs-producing strains were obviously higher than non-ESBLs-producing strains.Among 44 S.aureus strains, 26 were methicillin-resistant S.aureus (MRSA), resistance rate of S.aureus to penicillin was 97.73%, to vancomycin, teicoplanin, and linezolid were all 0, to the other antimicrobial agents were 9.09%-61.36%.Conclusion Bacteria is the major pathogen causing lower respiratory tract infection in hospitalized patients, but fungus and Mycobacterium can not be ignored.Resistance rates of P.aeruginosa to commonly used antimicrobial agents is relatively low, but resistance of A.baumannii is more serious.

Objective To investigate antibiotic resistance and resistant trend of Streptococcus pneumonia. Methods To investigate 753 Streptococcus pneumoniae isolated from Tongji Hospital in recent 10 years from January 1st 2000 to December 31st 2009, most of them were from respiratory tract specimens,followed by blood and cerebrospinal fluid. The MIC to penicillin & cefatriaxone were determined by E-test,and other antimicrobial susceptibility were tested by Kirby-Bauer method. Results For non-cerebrospinal fluid specimen, the total rate of PNSSP was 23.8%( 93/392 ), it was significant different between the rate of PNSSP from children ( 26. 4%, 47/178 ) and adults ( 16. 8%, 36/214, χ2 = 7. 642, P ＜ 0. 01 ). All of 10 strains isolated from cerebrospinal fluid were PRSP. Most isolates were high-susceptive to moxifloxacin and levofloxacin, and the rate of susceptibility were 96. 9% ( 720/743 ) and 90. 5% ( 672/743 )respectively. None of Streptococcus pneumonia was resistant to vancomycin and meropenam. The resistant rate of most tested antibiotics increased in different degree year by year, especially penicillin, erythromycin and clindamycin. The rate of PNSSP was only 19%( 19/99 )in 2006 ,but in 2009 the rate increased to 30%( 35/114 ). The susceptibility rate of erythromycin was 22% ( 28/125 )in 2000, but only 3% ( 3/114 )in 2009 ;and the susceptibility rate of clindamycin decreased from 40% ( 13/32 ) in 2004 to 4% (5/114) in 2009. Conclusions From 2000 to 2009, Streptococcus pneunoniae was more likely resistant to penicillin,erythromycin and clindamycin year by year, especially those isolates recovered from children. It was suggested that antibiotics should be chosen to use according to antimicrobial susceptibility test results.

Objective To investigate distribution and drug resistance of pathogenic bacteria in lower respitatory tract infection. Methods Distribution and drug resistance of pathogenic bacteria in lower respitatory tract infection of patients in ICU and non-ICU of our hospital during 2013 were retrospectivly analyzed. The pathogens were identified by manual methods routinely and those difficult to be identified were analyzed by using the VITEK-2-COMPACT instrument. Antimicrobial susceptibility of these isolates were tested by Kirby-Bauey methods routinely. Results In total, 956 strains were isolated from lower respitatory tract infection of patients in ICU, including 231 strains of gram-positive cocci (24. 2%), 680 strains of gram-negative bacteria (71. 1%), 45 strains of fungi (4. 7%). In patients of non-ICU, 4 464 strains were isolated, including 1 090 strains of gram-positive cocci (24. 4%), 3 226 strains of gram-negative bacteria (72. 3%), and 148 strains of fungi (3. 3%). Staphylococcus aureus, acinetobacter baumannii and pseudomonas aeruginosa were the most frequent isolates in patients of ICU and non-ICU. The overall prevalence of methicillin resistant staphylococcus aureus (MRSA) in staphylococcus aureus was 87. 0%in ICU and 74. 0% in non-ICU. MSSA was sensitive to the most antibiotics ( more than 80. 0% of the strains were sensitive to common antibiotics) except penicillin, erythromycin and clindamycin. MRSA was sensitive to trimethoprim-sulfamethoxazole and fosfomycin (more than 75. 0% of the strains were sensitive to the antibiotics) except for vancomycin, teicoplanin and linezolid. Acinetobacter baumannii was more resistant to the antibiotics (less than 40. 0% of the strains were susceptible to the antibiotics). Pseudomonas aeruginosa from ICU was more resistant to the antibiotics ( less than 50. 0% of the strains were sensitive to the antibiotics) than that from non-ICU. Stenotrophomonas maltophilia was sensitive to trimethoprim-sulfamethoxazole, levofloxacin and minocycline (more than 80. 0% of the strains were sensitive to the antibiotics). Escherichia coli and Klebsiella pneumoniae were sensitive to Piperacillin-tazobactam and Amikacin except for meropenem and imipenem ( more than 80. 0% of the strains were sensitive to the antibiotics) . Conclusion Gram-negative bacteria was the most frequent isolate in lower respitatory tract infection of our hospital during 2013. Staphylococcus aureus, acinetobacter baumannii and pseudomonas aeruginosa were the most frequent isolates in ICU and non-ICU. Resistance to the antibiotics was more common in ICU than in non-ICU. Antibiotics should be prescribed according to bacterial resistance results reasonably in order to prevent the spread of drug-resistant strains.

Objective To investigate the distribution and antibiotic resistance of bacterial isolates from blood samples in pediatric patients in tertiary hospitals in Hubei area from 2006 to 2007.Methods Pathogenic bacteria isolated from blood samples of pediatric patients were collected from 17 tertiary hospitals in Hubei area from 2006 to 2007. All strains were isolated and identified by routine Methods . Antimicrobial susceptibility testing was conducted on all isolates using Kirby-Bauer Methods . Results A total of 941 strains were collected from January to December of 2006. The most common microorganism was coagulase-negative Staphylococcus (573, 60.9%), followed by Staphylococcus aureus (127, 13.5%), Enterococcus faecalis (33, 3.5%), Escherichia coli (16, 1.7%). A total of 969 strains were collected from January to December of 2007. The most common species was coagulase negative Staphylococcus (583, 60.2%), followed by S. aureus (162, 16.7%), E. faecalis (28, 2.9%), E. coli (21, 2.2%), E. faecium (11, 1.1%), Salmonella choleraesuis (11, 1.1%). Of the isolates collected during 2006, the prevalence of methicillin-resistant S. aureus (MRSA) was 71.7%. The prevalence of ESBLs was 56.2% in E. coli. Of the isolates collected during 2007, the prevalence of MRSA was 79.6%. The prevalence of ESBLs was 47.6% in E. coli. MRSA strains were more resistant to antibiotics than methicillin-susceptible S. aureus (MSSA). No glycopeptide-resistant strain was identified in Staphylococcus. Conclusions Staphylococcus is the most frequently isolated pathogen from blood samples of pediatric patients in tertiary hospitals in Hubei area.

Objective To investigate the distribution and antibiotic resistance of the pathogens isolated from blood of the inpatients in hematology ward.Methods Antimicrobial susceptibility test was carried out using Kirby-Bauer method.The data were analyzed by WHONET 5.6 software.Results Of the 521 microbial isolates collected,gram-negative bacilli accounted for 47.2％,grampositive cocci 45.7％ and fungi (7.1％).The most frequently isolated microorganisms were coagulase negative Staphylococcus (154),E.coli (88),K.pneumoniae (51),P.aeruginosa (39) and Enterococcus spp (34).ESBLs were produced in about 40.4％ of the K.pneumoniae isolates and 63.4％ of the E.coli isolates.At least 90％ of the E.coli isolates were susceptible to imipenem and meropenem,and at least 70％ susceptible to piperacillin-tazobactam.At least 85％ of the K.pneumoniae strains were susceptible to imipenem and meropenem,and at least 70％ susceptible to levofloxacin,piperacillin-tazobactam and cefoperazone-sulbactam.The percentage of the P.aeruginosa susceptible to ciprofloxacin and tobramycin was at least 90％,and higher than 70％ to levofloxacin,meropenem,imipenem,piperacillin-tazobactam,cefepime,and cefoperazone-sulbactam.More than 90％ strains of the coagulase negative Staphylococcus and Enterococcus were susceptible to linezolid and teicoplanin.Overall,82.5％ of the coagulase negative Staphylococcus isolates were resistant to methicillin.Three E.coli isolates and 4 K.pneumoniae isolates were found resistant to carbapenems,and 14 Enterococcus isolates were resistant to vancomycin.Conclusions Gram-negative bacilli are the major pathogens from blood samples in hematology ward,which show high susceptibility to piperacillin-tazobactam and cefoperazone-sulbactam,imipenem and meropenem.The grampositive cocci show high susceptibility to linezolid and teicoplanin.These data are helpful for empirical antimicrobial therapy.

Objective To investigate the distribution,variability and antibiotic resistance of the pathogen sisolated from bloodstream infections.Methods The bacterial strains were routinely isolated from blood samples and identified.Brucella trains were identified by PCR and gene sequencing.Antimicrobial susceptibility were routinely tested for these isolates.Results A total of 2 152 strains,excluding coagulase negative Staphylococcus,were isolated from blood specimens during the 5-year period from 2009 through 2013.Gram-positive cocci,gram-negative bacilli and fungi accounted for 35.3% (761/2 152), 57.7% (1 242/2 152)and 6.9% (149/2 152),respectively.The top three gram-positive bacteria were S.aureus,E.faecium and E.faecalis.E.coli,K.pneumoniae,P .aeruginosa,A.baumannii,and Brucella were the most frequently isolated gram-negative bacteria.In 2009,only one Brucella melitensis was isolated,but increased to 50 in 2013 (7.1%),including one strain of Brucella suis .The prevalence of MRSA was 54.1% in S.aureus.No staphylococcal isolate was found resistant to vancomycin or linezolid.More than 60% of the E.faecalis isolates still showed low resistance (< 30%)to ampicillin and levofloxacin.But E.faecium strains were highly resistant to most antibiotics (>70%)except glycopeptides and linezolid.E. coli and K.pneumoniae isolates displayed low resistance rate (< 15%)to piperacillin-tazobactam,amikacin,cefoxitin and
were still the most common pathogens in blood stream infections.Attention should be paid to the increasing prevalence of Brucella in blood stream infections.Various levels of antibiotic resistance are found in the pathogens of blood stream infections.Antibiotics should be prescribed reasonably according to local susceptibility testing data.

Objective To investigate the antimicrobial resistance in the clinical strains isolated from Tongji Hospital to the antimicrobial agents commonly used in 2012.Methods Antimicrobial susceptibility was tested by Kirby-Bauer method.The minimum inhibitory concentration (MIC) of penicillin and ceftriaxone for Streptococcus pneumoniae and vancomycin for Staphylococcus spp.were determined by E-test.All data were analyzed by WHONET 5.6 software.Results A total of 8 191 strains were isolated in 2012,including gram-positive bacteria (2 815,34.4%)and gram-negative bacteria (5 376,65.6%). The top five pathogenic bacteria isolated from outpatients were Escheria coli,Pseudomonas aeruginosa,coagulase-negative Staphylococcus (CNS),Klebsiella spp.and Staphylococcus aureus.For the isolates from non-ICU inpatients,the top five were E.coli,S.aureus,Acinetobacter spp.,Klebsiella spp.and P.aeruginosa.For those isolated from ICU patients,the top five were Acinetobacter spp.,S.aureus,P.aeruginosa,Enterococcus spp.and E.coli.The prevalence of MRSA and MRCNS was 58.1% and 64.3%,respectively.Seventeen strains of vancomycin resistant Enterococcus were identified, including 13 strains of E.faecium with VanA and 4 strains of E.gallinarum with VanA and VanC.The percentage of antimicrobial resistance in E.faecium was significantly higher than that in E.faecalis (P<0.05).A total of 94 strains of carbapenem-resistant Enterobacteriaceae were detected.The prevalence of penicillin-non-susceptible S.pneumoniae in children was much higher than that in adults. The prevalence of carbapenem-resistant P.aerugonosa and Acinetobacter spp. was 28.1% and 56.2% respectively.Beta-lactamase was produced in 41.8% of the H.influenzae and 98.6% of the M. catarrhalis isolates. Conclusions The prevalence of multidrug resistant strains has been increasing, especially vancomycin-resistant Enterococcus and carbapenem-resistant Enterobacteriaceae.

Objective:To retrospectively analyze the clinical characteristics and drug resistance among COVID-19 patients with bacterial and fungal infections.Methods:Clinical data of COVID-19 patients whose blood, urine, sputum and alveolar lavage fluid samples were positive for bacteria and fungi were collected in Tongji Hospital from February 10 to March 31, 2020. WHONET5.6 software was used to analyze drug susceptibility test results.Results:A total of 95 COVID-19 patients positive for pathogenic bacteria were enrolled and among them, 23 were non-critical patients and 72 were critical patients. The main symptoms in these patients included fever, cough with sputum, fatigue and dyspnea. Male and female critical patients accounted for 63.89% and 36.11%, respectively. Most of the patients with bacterial and fungal infections were critical type, accounting for 23.61%. The mortality rates of non-critical and critical patients were 13.04% and 61.11%, respectively. A total of 179 strains of pathogenic bacteria were isolated. The positive rate of Escherichia coli in non-critical patients was 37.50%, which was higher than that in critical patients. However, the positive rates of Acinetobacter baumannii and Klebsiella pneumoniae in critical patients were both 29.87%, higher than those in non-critical patients. There was no significant difference in the positive rate of gram-positive bacteria or fungi between non-critical and critical patients. It was noteworthy that the positive rate of Candida parapsilosis in blood samples of critical patients was relatively high, reaching 36.40%. Drug susceptibility test results showed that no carbapenem-resistant Escherichia coli stains were detected and 60.87% of Klebsiella pneumoniae strains were resistant to carbapenems. Acinetobacter baumannii strains were 100% resistant to three antimicrobial drugs. Methicillin-resistant Staphylococcus aureus strains accounted for 71.43%, but no vancomycin-resistant gram-positive cocci were found. Conclusions:Critical COVID-19 patients were mostly male and prone to multiple bacterial and fungal infections. The mortality of critical patients was higher than that of non-critical patients. Critical COVID-19 was often complicated by hospital acquired infections caused by bacteria including Acinetobacter baumannii and Klebsiella pneumoniae with high drug resistance.

Objective To investigate the antimicrobial resistant mechanisms of carbapenemrcsistant Entcrobactcriaceae (CRE),construct monitoring system of acquired carbapenemase.Methods Totally 5604 clinical isolates of Enterobacteriaceae in Tongji Hospital were collected from January 2007 to June 2010,including 100 isolates of which zone diameters of meropenem were not larger than 21 mm.Antibiotic susceptibility was performed to select CRE.Then,carbapanemase gene and genetie structure screenings were perforomed by polymerase chain reaction (PCR).Pulsed-field gel electrophoresis (PFGE) and Southern blot were used to analyze the plasmids of CRE.Multilocus sequence typing (MLST) was used to determine the genotypes and homology of these isolates.In addition,out membrane proteins were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis ( SDS-PAGE ).Results Eleven isolates of CRE were collected and confirmed,most of them were Klebsiella.spp.( 7/11 ).Susceptibility of antimicrobial agents indicated that all these strains resistant to most antimicrobials.The minimal inhibitory concentration (MIC) range of meropenem were 8 - 64 mg/L,imipenem were 4 - 64 mg/L,ertapenem were 4 - 64 mg/L.However,susceptibilities of aminoglycosides and fluoroquinoloncs were significantly different.PCR results showed that six isolates were blaIMP-4 positive and three isolates were blakPC.2 positive,including one isolate of K.pneumoniae (ST476) carrying both blaIMP-4 and blaKPC-2 genes.Genetic structure of carbapenemase genes were analyzed,suggesting that blaKPC-2 located in an integrated structure of a Tn3-based transposon and partial Tn4401 segment.PFGE showed that most CRE contained three or more plasmids.Two isolates of K.pneumoniae were assigned to the same sequence type,ST476,by MLST.SDS-PAGE indicated that only one isolate (Kox656) lacked two out membrane proteins ( OmpK35 and OmpK36 ).Conclusions The most common carbapenemase-resistant Enterobacteriaceae was K.pneumoniae in our hospital.Producing IMP-4 was the most common reason that bacteria resistant to carbapencms.The concomitant presence of these genes poses therapeutic as well as infection control problems.Attention should be payed to the characteristies of bacterial resistance and clinical epidemiology of drug-resistant infections in hospital,and thus to provide clinical reference.

Objective To evaluate the capability of four tests for identification of the in vitro suscepti-bility of tigecycline against Acinetobacter and Enterobacteriaceae isolates.Methods Disk diffusion test was per-formed to detect the sensitivity of 158 Acinetobacter and 339 Enterobacteriaceae isolates to tigecycline.The mini-mum inhibitory concentrations ( MICs) of tigecycline for non-sensitive isolates were detected by using broth dilu-tion method ( BDM) , MIC Test Strip ( MTS) and agar dilution method.The differences with antimicrobial sus-ceptibility among the four different methods were evaluated.Results Tigecycline showed good antibacterial ac-tivity against both non-sensitive Acinetobacter and Enterobacteriaceae isolates with most of the MIC50 values in the sensitivity range of (0.5-2) mg/L and all of the MIC90 values of 4 mg/L.The MIC50 and MIC90 values measured by BDM were respectively 1 mg/L and 4 mg/L.The sensitivity rates presented by the results of BDM were re-spectively 87.1%and 70.2%based on the standards made by Food and Drug Administration (FDA) and Euro-pean Committee on Antimicrobial Susceptibility Testing ( EUCAST) .Agar dilution method indicated that most of the MICs of tigecycline to Acinetobacter and Enterobacteriaceae isolates were two dilutions higher than those de-tected by BDM with essential agreement (EA) rate of 56.5%.Both the very major error (VME) and the major error (ME) values were 0 and the categorical agreement (CA) rate was 46.8%according to the FDA standard.The VME and CA values were 0.8% and 24.2% based on EUCAST standard.Compared with agar dilution method, MTS showed better results in determining the susceptibility of Acinetobacter and Enterobacteriaceae iso-lates to tigecycline with MIC50 and MIC90 values of 1.5 mg/L and 4 mg/L, which was similar to the capability of BDM.Referring to the FDA and EUCAST standards, the sensitivity rates were 83.1% and 21.0%, the CA rates was 81.5%and 29.8%, and the EA rate was 71.8%.Most of the results tested by MTS were one dilution higher than those by BDM.FDA standard showed better correlation than EUCAST standard.Disk diffusion method showed the ME, mE, VME and CA values were respectively 19.4%, 71.8%, 0 and 8.9%according to FDA standard.Conclusion Disk diffusion method, MTS and agar dilution method all showed differences with BDM in susceptibility testing.The capability of MTS was similar to that of BDM.The results evaluated by FDA standard were better than those by EUCAST standard.The in vitro susceptibility of bacteria to tigecycline could be tested by disk diffusion method using FDA standard for evaluation, and confirmed with MTS if isolates were resistance or intermediate strains.The BDM could be performed for further confirmation if necessary.