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With the improved understanding of driver mutations in non-small cell lung cancer (NSCLC), expanding the targeted therapeutic options improved the survival and safety. However, responses to these agents are commonly temporary and incomplete. Moreover, even patients with the same oncogenic driver gene can respond diversely to the same agent. Furthermore, the therapeutic role of immune-checkpoint inhibitors (ICIs) in oncogene-driven NSCLC remains unclear. Therefore, this review aimed to classify the management of NSCLC with driver mutations based on the gene subtype, concomitant mutation, and dynamic alternation. Then, we provide an overview of the resistant mechanism of target therapy occurring in targeted alternations ("target-dependent resistance") and in the parallel and downstream pathways ("target-independent resistance"). Thirdly, we discuss the effectiveness of ICIs for NSCLC with driver mutations and the combined therapeutic approaches that might reverse the immunosuppressive tumor immune microenvironment. Finally, we listed the emerging treatment strategies for the new oncogenic alternations, and proposed the perspective of NSCLC with driver mutations. This review will guide clinicians to design tailored treatments for NSCLC with driver mutations.
Subject(s)
Humans , Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/genetics , Mutation , Tumor Microenvironment/geneticsABSTRACT
Objective:This work aims to investigate the phenotype-characteristics of drug resistance and the possible mechanisms of extensively drug-resistance Klebsiella pneumoniae(XDRKP). Methods:Screened by the previous drug susceptibility results, 116 clinical Klebsiella pneumoniae isolates were collected from Shanxi Bethune Hospital from January 2018 to December 2020. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) rapid microbial identification system and VITEK-compact 2 were used. The modified carbapenem inactivation method (mCIM) combining with EDTA carbapenem inactivation method (eCIM) was used to identify the strains′ carbapenemase phenotypes, which were compared with subsequent qPCR results. The qPCR amplification combining with agarose gel electrophoresis were carried out to detect various drug-resistant related genes, including: carbapenemase genes: blaKPC, blaNDM, blaVIM, blaIMP, blaOXA; aminoglycosides resistance genes: ① 16S rRNA methylase genes: rmtA, rmtC, rmtD, rmtG, rmtH, armA, npmA, rmtB, rmtE, rmtF, ② variant of aminoglycosides acetyltransferase gene: aac(6′)-Ib-cr; quinolone resistance genes: DNA gyrase protection protein qnr family: qnrA, qnrB, qnrC, qnrD, qnrS, efflux pump protein gene: oqxAB, qepA, variant of aminoglycoside acetyltransferase gene: aac(6′)-Ib-cr; and tigecycline-resistant Tet protein genes: efflux pump protein gene: tet (A), tet (L), ribosome protection protein gene: tet (M), tigecycline modified enzyme gene: tet (X). Each isolate′s phenotype and resistance gene result were compared and analyzed correspondingly. Results:A total number of 116 XDRKP isolates were collected in 3 years, 115 of which are identified as carbapenem resistant. Both cephalosporins and quinolones resistant rate were 100%, while the resistant rate of aminoglycosides antibiotic gentamicin, tobramycin and amikacin was 95.69% (111/116), 94.83% (110/116), or 88.79% (103/116) respectively. Sulfonamide antibiotics and tigecycline showed a relatively lower resistant rate. Compared with PCR amplification results, mCIM combining with eCIM phenotype testing had a high conformity, up to 95.65% (110/115). Positive rate of each resistance related gene was: blaKPC 90.52% (105/116), blaNDM 10.34% (12/116), rmtB 81.90% (95/116), armA 2.59% (3/116), oqxAB 65.52% (76/116), qnrB 6.03% (7/116), qnrS 12.93% (15/116), aac(6′)-Ib-cr 7.76% (9/116), or tet(A) 21.55% (25/116), respectively. Other resistance related genes were not detected. Corresponding analysis between the resistant phenotypes and resistance related genes indicated that a total of 65 XDRKP didn′t have a matched pairs, i.e. bacteria′s resistance to specific antibiotic could not be interpreted by carrying some associated resistant genes.Conclusions:The wide distribution of resistant genes and multiple-antibiotic-inactivated trait of some genes(such as aac(6′)-Ib-cr and oqxAB) in XDRKP are potential causes of the generation of extensively drug resistant phenotype. Different XDRKP isolates may carry one or more resistant genes in responding to specific antibiotic. In addition, there are some bacteria with an unmatched phenotype-gene feature indicating that both resistance genes′ regulation and some other mechanisms also play a role in development of XDR.
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Objective@#To investigate the molecular epidemiology and mechanisms of fosfomycin-resistant Escherichia coli isolates producing extended-spectrum β-lactamases (ESBLs) isolated from urine. @*Methods@#Fosfomycin-resistant phenotypes were screened by drug susceptibility test in ESBLs-producing E.coli stains. The ESBLs gene and fosfomycin resistant gene were amplified by PCR. The molecular typing was analyzed by multiple sequence type (MLST). The transferability of the drug resistant gene was verified by conjugation assays. @*Results@#Among the 308 strains of E.coli isolated from urine, there were 168 (54.54%) ESBLs producing strains and 18 (10.71%, 18/168) fosfomycin resistant strains. In the drug resistant genes, the incidence of bla SHV was about 88.9% (16/18), bla CTX-M was 77.8% (14/18), bla TEM-208 was 5.6% (1/18), bla TEM-1b was 61.1% (11/18) and fosA3 was 83.3% (15/18). The main MLST genotype was ST131. The conjugation test confirmed the transferability of resistance in fosA3 positive strain. @*Conclusion@#The fosfomycin resistant rate of ESBLs producing E.coli in urethral infection was in a low level. The fosA3 gene was the main mechanism of fosomycin resistance and located on the conjugation plasmids, which should be the main node of horizontal gene transmission. We need to pay great attention to this resistant gene.
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Objective:To investigate relationship between AdeABC efflux pump and resistance of Acinetobacter baumannii against carbapenem.Methods:Carbapenem-resistant strains were acquired from multistep selection resistance test by meropenem in vitro.The quantitation test for sensitivities of strains before and after induction was determined by the E-test,and carbonylcyanide-m-chlorophenylhydrazone (CCCP) inhibition test was used to screen efflux pump.PCR,sequencing analysis,or real-time PCR was used to analyze the changes of regulatory genes adeR and adeS of the AdeABC efflux pump system,or expressions of adeA,adeB,adeR,and adeS in the strains before and after induction,respectively.Results:The minimal inhibitory concentrations (MICs) of meropenem were at 0.38 μg/mL and 0.25 μg/mL in parental sensitive strain S25595 and S7257,respectively,and the MICs of meropenem for both S25595 and S7257 after induction were more than 32 μg/mL.Compared with parental sensitive strains,the expression level of adeA,adeB,adeR,and adeS mRNA were elevated from 2.45 to 9.44 times,but there were no gene mutations or insertion sequences in the regulatory gene adeS and adeR.Conclusion:High expression of the AdeABC efflux pump system in Acinetobacter baumannii is closely associated with meropenem resistance,The upregulation of adeA and adeB expression is not due to gene mutations in the regulatory gene adeS and adeR and other mechanisms might account for it.
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Objective To investigate the prevalence of plasmid-mediated quinolone resistance(PMQR) in Proteus mirabilis clinical isolated from urine. Methods Antimicrobial susceptibility test was performed using the microdilution method.And PMQR gene qnrA,qnrB,qnrC,qnrD,qnrS,aac(6′)-Ib-cr,qepA were amplified by PCR,then the PCR positive products were sequenced to identify their genotypes. Results In 41 strains of Proteus mirabilis from urine,the resistant rates to ciprofloxacin and levofloxacin were 41.5% and 29.3%,respec-tively.Among all clinical isolates,qnrA1 gene was detected in 2 strains,qnrB2 gene in 3 strains.PMQR gene qn-rB,qnrC,qnrD,qnrS,aac(6')-Ib-cr and qepA were not detected in all strains.Conclusions Clinical isolates of Proteus mirabilis from urine carry PMQR genes.The prevalent principal genotypes are qnrA1 and qnrB2 in these iso-lates.They are related to low levels resistance toquinolone.
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The resistance to PBK-Akt-mTOR pathway inhibitors has close relationship to the negative feedback of its context-dependent signal pathways. According to our current understanding, the resistant mechanisms could be divided into the following basic conditions: related to FOXO and hormone receptor, MYC-dependence, β-catenin-dependence, JAK/STAT pathway-dependence, MAPK pathway-dependence and related to AXL. The emergence of drug resistance to PBK-Akt-mTOR pathway inhibitors has greatly limited their curative effect. The reported resistance mechanisms to PBK-Akt-mTOR pathway inhibitors to search for potential strategies for overcoming resistance by drug combination were summarized.
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Objective To investigate the antimicrobial‐resistant profile and genes carried by 80 staphylococcus aureus and analy‐size its antimicrobial‐resistant mechanism .Methods The bacteria identification and the antimicrobial susceptibility test were con‐ducted by VITEK‐2 compact automatic system .Methicillin resistant taphylococcus aureus (MRSA) were screened by disk diffusion method with cefoxitin .The polymerase chain reaction(PCR)was used to detect the antimicrobial‐resistant genes .Results The re‐sistance rates of 80 staphylococcus aureus to penicillin ,erythromycin and gentamicin were 91 .25% ,85 .0% and 71 .25% ,respective‐ly .All of the isolates were susceptible to linezolid ,vancomycin ,teicoplanin and tigecycline .Among the 80 isolates ,there were 22 MRSA ,accounting for 27 .5% ,and 13 were inducible antimicrobial‐resistant .57 (71 .25% ) carried antimicrobial‐resistant genes ,in‐cluding 6 genes .Of which ,21(26 .25% )carried ermB and aac(6′)/aph(2) simultaneously ,9(11 .25% )carried ermA ,mecA ,qacA simultaneously ,and all of the 9 were MRSA ,13(16 .25% ) only carried ermC .Conclusion The resistance rates of staphylococcus aureus were high to penicillin ,erythromycin and gentamicin .The various antimicrobial‐resistant genes were positive in staphylococ‐cus aureus .We should pay attention to the detection of the antimicrobial‐resistant gene and choose antibacterial drug rationally .
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Objective To investigate the mechanism of resistance of clinical isolates of Pseudomonas aeruginosa to carbapenems.Methods Fifty-eight strains of imipenem-and meropenem-resistant Pseudomonas aeruginosa were isolated.Modified K-B technique was adopted in the susceptibility test by adding ?-lactamases inhibitors and efflux pumps inhibitors to M-H agar plates.The refined three-dimensional extract test was used to detect ?-lactamases.The genes of metallo-enzyme IMP,VIM,as well as outer membrane porin D2(OprD2) were analyzed with polymerase chain reaction.Results Among the 58 strains of carbapenems-resistant Pseudomonas aeruginosa,53 produced over-expressed active efflux and continuously produced large amont of AmpC enzyme,15 of which were accompanied by the loss of OprD2,and 1 of which were accompanied by extended spectrum ?-lactamases(ESBLs).Among the 5 strains which neither produced over-expressed active efflux nor ?-lactamases,only 1 was found with OprD2 gene deletion.Metallo-enzyme was not detected in any of the 58 strains.Conclusion The mechanism of resistance of Pseudomonas aeruginosa to carbapenems was mainly the production of the over-expressed active efflux combined with the continuous production of large amount of AmpC enzyme.Sixteen of the strains were accompanied by the loss of OprD2 gene.
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OBJECTIVE To investigate the resistant mechanisms of Candida albicans to azoles at molecular level.METHODS NCCLS M-27 protocols were used to test the in vitro susceptibilities of 102 C.albicans strains isolated from the patients with recurrent vulvovaginal candidiasis(RVVC) against fluconazole(FLC) and itraconazole(ITC) to screen the FLC-and ITC-resistant C.albicans isolates;six pairs of primers,A1-A2,B1-B2,C1-C2,D1-D2,E1-E2 and F1-F2 were respectively to amplify gene CYP51 of 4 strains with FLC-and ITC-resistance.The PCR products were sequenced and analyzed to identify the mutation sites by compared with the sequence of gene CYP51 of referenced C.albicans strain in NCBI site of Internet.RESULTS The analysis of full length sequence of CYP51 from 4 FLC-and ITC-resistant strains showed that from total 32 mutation sites there were 4 significant site mutations,where the mutation of GAT to GAC at 116 caused the substitution of D by E(E266D in two strains);GCC to GGT at 117 caused the substitution of A by G(A117G in 1 strain);GAA to GAC at 266 caused the substitution of E by D(E266D in 2 strains);and GTT to ATT at 488 caused the substitution of I by V(V488I in 1 strain).The site mutations of 266 and 488 were tested in 1 strain of 4 strains.CONCLUSIONS The CYP51 total gene of 4 strains has been checked out.Of FLC and ITC-resistant C.albicans alignment in this time,find out 4 significant bp mutations.Causing its amino acide change,among them,A117G has not be interrelated report still now.The details of mechanism need to be further studied.
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OBJECTIVE To investigate the distribution and drug resistance of Pseudomonas aeruginosa.METHODS All specimens isolated and cultured from patients in our hospital were identified by using the automatic microorganism analyzer WalkAway-40,Dade Behring made in America,and bacteria′s drug susceptibility test and identifications were performed on strains using NC21 Microscan Panel.RESULTS From sixty-two strains of P.aeruginosa 36 strains were isolated of sputum.The resistance rate to the third generation of cephalosporins cefotaxime and ceftriaxone was 55.6% and 47.5%,respectively.The resistance rate to the other ?-lactamases antibiotics such as ceftazidime was 7.5%,piperacillin/tazobactam 11.0%,cefepime 14.8% and penicillin was 30.0%,the ratio of resistance for imipenem was 20.0%,the lowest one was amikacin(4.6%).CONCLUSIONS P.aeruginosa is one of the main bacteria in the lower respiratory tract infection.The drug-resistant mechanism of P.aeruginosa is very complex,including multidrug resistance characteristics,and it is originally resistant to several antibiotics.To avoid being produced ?-lactamases and result in resisting drug widely,the antibiotics should be selected according to low drug-resistant rate and taking into account sufficiently its drug resistance mechanism in the treatment of P.aeruginosa infection.
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There exist a number of mercury-resistant bacterial in environment, Mer operon is involved in the resistant mechanism, MerRTPA of Mer operon encodes the proteins related to the regulation, transport and reduction of mercury ion, respectively. The toxic mercury ion is transported by MerTP from medium to cytoplasmic mercuric reductase, MerA, and deoxidized to non-toxic and volatile element mercury, Hg(0). Bacterial mercury-resistant system originated from ancient times, and evolved into the Mer operon with diversity by gene integration and insertion. Mercury-resistant bacteria highly specifically absorb mercury ion, and can be used in recovering the mercury-polluted environment as well as the genetic selective marker.