OBJECTIVETo investigate the resistance genes and antibiotic resistance patterns against beta-lactams in Pseudomonas aeruginosa prevalent in burn ward.

METHODSK-B method was performed to test bacterial resistance patterns against 9 species of beta-lactams in Pseudomonas aeruginosa isolated from wounds and dressings of the patient in burn wards. Seven species of resistance genes against beta-lactams were detected with PCR. Tazobactam-inhibited piperacillin resistance test was performed to study whether the above strains produce extended spectrum beta-lactams.

RESULTSAll 12 strains of bacteria with resistance genes detected were resistant to penicillin and cephalosporins (100%), among them 11 were resistant to all antibiotics. Tazobactam-inhibited piperacillin resistance test demonstrated that all strains with resistance genes were ESBLs.

CONCLUSIONHigh incidence of beta-lactams resistance genes is found in Pseudomonas aeruginosa isolated from burn ward, and they have close relationship with the occurrence of multiple drug-resistance.

Burn Units ; Burns ; microbiology ; Genes, Bacterial ; Humans ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification ; beta-Lactam Resistance ; genetics

BACKGROUND: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) and Acinetobacter baumannii (CRAB) are the leading causes of nosocomial infections. A rapid and sensitive test to detect CRPA and CRAB is required for appropriate antibiotic treatment. We optimized a loop-mediated isothermal amplification (LAMP) assay to detect the presence of bla(VIM-2), bla(IMP-1), and bla OXA-23, which are critical components for carbapenem resistance. METHODS: Two sets of primers, inner and outer primers, were manually designed as previously described. The LAMP buffer was optimized (at 2mM MgSO4) by testing different concentrations of MgSO4. The optimal reaction temperature and incubation time were determined by using a gradient thermocycler. Then, the optimized bla(VIM-2), bla(IMP-1), and bla(OXA-23) LAMP reactions were evaluated by using 120 P. aeruginosa and 99 A. baumannii clinical isolates. RESULTS: Only one strain of the 100 CRPA isolates harbored bla(IMP-1), whereas none of them harbored bla(VIM-2). These results indicate that the acquisition of bla(VIM-2) or bla(IMP-1) may not play a major role in carbapenem resistance in Korea. Fifty two strains of the 75 CRAB isolates contained bla(OXA-23), but none contained bla(VIM-2) and bla(IMP-1) alleles. CONCLUSIONS: Our results demonstrate the usefulness of LAMP for the diagnosis of CRPA and CRAB.
Acinetobacter baumannii/genetics/*isolation & purification ; Anti-Bacterial Agents/*pharmacology ; Carbapenems/*pharmacology ; Drug Resistance, Bacterial/*genetics ; *Genes, Bacterial ; Nucleic Acid Amplification Techniques ; Pseudomonas aeruginosa/genetics/*isolation & purification ; Sensitivity and Specificity

OBJECTIVETo investigate class I integrons and integrated gene cassettes in metalloenzyme-producing Pseudomonas aeruginosa.

METHODSA total of 68 isolated clinical strains of Pseudomonas aeruginosa were subjected to PCR analysis with primers specific for bla(IMP-1) and bla(VIM). The positive strains then underwent examination for class I integrons and integrated gene cassettes with PCR with primers specific to class I integrase ((IntI)1) and integrated gene cassettes, followed by sequence analysis for some of the positive strains.

RESULTSOnly 1 isolated strain showed positive results for both bla(IMP-1) and bla IntI1 detection. Fifty-five strains were positive for bla(VIM), including 26 positive for bla (IntI)1. Of the 26 bla (IntI)1-positive strains, only 18 contained integrated gene cassettes, which were classified into 5 types according to agarose gel electrophoresis.

CONCLUSIONIt is the first time to identify IMP-1-producing Pseudomonas aeruginosa carring bla(Int)1 in West China. The class I integrons were widespread in these Pseudomonas aeruginosa and 69.2% of them carry the gene cassettes. These findings provide useful insights into the clinical spread of these drug-resistant genes.

Bacterial Proteins ; genetics ; metabolism ; DNA, Bacterial ; analysis ; genetics ; Drug Resistance, Bacterial ; genetics ; Electrophoresis, Agar Gel ; Humans ; Integrons ; genetics ; Polymerase Chain Reaction ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; enzymology ; genetics ; isolation & purification ; Species Specificity ; beta-Lactamases ; genetics ; metabolism

OBJECTIVETo investigate drug-resistant genes associated with beta-lactams and aminoglycosides in clinically isolated Pseudomonas aeruginosa.

METHODSTwenty strains of Pseudomonas aeruginosa were isolated from wound excretion of hospitalized burn patients. The strains resistant to 14 antibiotics were selected for detection of 16 kind of drug-resistant genes (TEM, SHV, OXA-10 cluster, PER, VEB, GES, CARB, CTX-M- I, IMP, VIM, SPM, GIM, DHA, MOX, FOX, oprD2) and 6 kind of aminoglycoside modification genes (aac(3)- I, aac(3)-II, aac(6')-I, aac(6')-II, ant (3")- I , ant(2")- I) in them by PCR.

RESULTSAmong the 20 strains resistant to beta-lactam , all of them were TEM and GES positive (100%), oprD2 gene depletion in 5 strains (25%). All other genes were negative. Among aminoglycoside resistant genes, 20 strains were aac (6') - I positive (100%), 7 were ant (2") - I positive (35%), and negative for other stains.

CONCLUSIONThere were very high existence rates of TEM, GES and aac (6')- I genes in Pseudomonas aeruginosa isolated from clinical burn patients. The fact that GES-5 gene has also been detected in Pseudomonas aeruginosa, suggesting this organism is highly drug resistant in our burn unit.

Aminoglycosides ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification ; beta-Lactam Resistance ; genetics ; beta-Lactams ; pharmacology

The 16S rDNA specific primers were designed for rapid detection of Pseudomonas aeruginosa (PA) by the fluorescence quantitative PCR (FQ-PCR) assay, based upon multiple sequence alignment and phylogenetic tree analysis of the 16S rDNAs of over 20 bacteria. After extraction of PA genomic DNA, the target 16S rDNA fragment was amplified by PCR with specific primers, and used to construct recombinant pMDT-Pfr plasmid, the dilution gradients of which were subjected to the standard quantitation curve in FQ-PCR assay. Different concentrations of PA genomic DNA were detected by FQ-PCR in a 20microL of reaction system with SYBR Green I. At the same time, various genomic DNAs of Staphylococcus aureus, Salmonella typhi, Shigella flexneri, Proteus vulgaris, Staphylococcus epidermidis, Escherichia coli, and Mycobacterium tuberculosis were used as negative controls to confirm specificity of the FQ-PCR detection assay. Results demonstrated that the predicted amplified product of designed primers was of high homology only with PA 16S rDNA, and that sensitivity of the FQ-PCR assay was of 3.6pg/microL of bacterial DNA or (2.1 x 10(3) +/- 3.1 x 10(2)) copies/microL of 16S rDNA, accompanied with high specificity, and that the whole detection process including DNA extraction could be completed in about two hours. In contrast to traditional culture method, the FQ-PCR assay targeting 16S rDNA gene can be used to detect PA rapidly, which exhibits perfect application prospect in future.
Base Sequence ; DNA, Ribosomal ; genetics ; Fluorescence ; Molecular Sequence Data ; Polymerase Chain Reaction ; methods ; Pseudomonas aeruginosa ; genetics ; isolation & purification ; RNA, Ribosomal, 16S ; genetics

OBJECTIVETo study the resistance mechanism and homology of carbapenems-resistant Pseudomonas aeruginosa (PA).

METHODSA total of 812 strains of PA (identified) were isolated from sputum, urine, blood, pus, and drainage of patients with burn, severe pneumonia, diabetes, chronic obstructive pneumonia, myocarditis, liver transplantation, or brainstem hemorrhage hospitalized from January to September 2012. Drug resistance of the 812 strains of PA to 15 antibiotics commonly used in clinic, including piperacillin, imipenem, etc., was tested using the automatic microorganism identifying and drug sensitivity analyzer. Among the carbapenems-resistant PA isolates, synergism test with imipenem-ethylene diamine tetraacetic acid (EDTA) and enhancement test with imipenem-EDTA and ceftazidime-EDTA were used to screen metallo-β-lactamase (MBL)-producing strains; modified Hodge test was used to screen strains producing Klebsiella pneumoniae carbapenemases (KPC); the carbapenemase gene, plasmid mediated quinolone resistant (PMQR) gene, and mobile genetic elements (MGE) were detected by polymerase chain reaction (PCR). In addition, a comparative analysis of the PMQR gene carrying level between the carbapenemase gene positive strains and carbapenemase gene negative strains was carried out. The repetitive consensus sequence of Enterobacteriaceae genome PCR (ERIC-PCR) was carried out for gene typing. Moreover, the source and resistance genes of strains with the same genotype were analyzed. Data were processed with Fisher's exact probability test.

RESULTSThe sensitive rates of the 812 strains of PA to ceftriaxone and trimethoprim-sulfamethoxazole were high, respectively 83.07% and 88.19%, and those of the other antibiotics ranged from 17.30% to 55.18%. Twenty-four carbapenems-resistant PA strains were screened, including 11 MBL-producing strains and 2 KPC-producing strains. Eleven carbapenems-resistant PA strains were found to harbor the blaVIM-2 gene, accounting for 45.83%; 2 carbapenems-resistant PA strains carried the blaKPC-2 gene, accounting for 8.33%. Fourteen carbapenems-resistant PA strains only harbored the PMQR gene acc (6')-Ib-cr, accounting for 58.33%; 3 carbapenems-resistant PA strains (12.50%) harbored the PMQR genes acc (6')-Ib-cr and qnr, including 1 strain with qnr A1 and 2 strains with qnr B4. Ten carbapenems-resistant PA strains carried the MGE gene ISCR1, accounting for 41.67%; 6 carbapenems-resistant PA strains carried the MGE gene ISEcp1, accounting for 25.00%. In addition, 3 carbapenems-resistant PA strains co-harbored the MGE genes ISCR1 and ISEcp1 (accounting for 12.50%), while only 1 carbapenems-resistant PA strain co-harbored the MGE genes class 1 integron and ISEcp1, accounting for 4.17%. Twelve out of the 13 carbapenemase gene positive strains carried one or two PMQR gene (s), which was significantly higher than that of the carbapenemase gene negative strains (with only five strains harboring one PMQR gene, P = 0.023). The 24 carbapenems-resistant PA strains were classified into 6 genotypes by the ERIC-PCR. Thirteen strains (accounting for 54.17%), mainly isolated from pus and blood samples, which were collected from burn department, were in genotype A. Eight out of the 13 strains harbored genes blaVIM-2, acc (6')-Ib-cr, and ISCR1. Five strains (accounting for 20.83%), mainly isolated from sputum samples which were collected from ICU, were in genotype B. Only 2 out of the 5 strains co-harbored the carbapenemase gene, PMQR gene, and MGE gene. There were respectively 2 strains in genotypes C and D, both accounting for 8.33%; the strains in different pattern were isolated from different wards, and they harbored diverse resistance genes. There were respectively 1 strain in genotypes E and F, both accounting for 4.17%.

CONCLUSIONSThe resistance mechanism of PA to carbapenems is mainly mediated by the VIM-2 type MBL in our hospital during 2012, followed by KPC-2 type carbapenemase, and the prevalent genotype is type A. The carbapenemase genes and PMQR genes co-carrying phenomenon exists among these strains of PA, which disseminated by clones.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; Carbapenems ; pharmacology ; DNA, Bacterial ; Drug Resistance, Bacterial ; Humans ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification ; beta-Lactamases ; genetics

OBJECTIVETo study the clinical significance of virulence genes exo U and exo S of type III secretion system (TTSS) of Pseudomonas aeruginosa (PA).

METHODSOne hundred and eighty-nine clinical isolates of PA were collected from five hospitals. The incidence of virulence genes exo U and exo S in PA were determined with PCR. Minimum inhibitory concentration of anti-bacterial drug for PA was determined with microdilution method. The clinical features and outcomes of 60 hospitalized patients colonized or infected with exo U+/exo S- positive or exo U-/exo S+ positive PA isolated from sputum were analyzed retrospectively. Data were processed with chi-square test.

RESULTSAmong the 189 PA isolates, 85.2% (161/189) harbored TTSS genes, including exo U-/exo S+ type (120 isolates), exo U+/exo S- type (31 isolates), exo U-/exo S- type (7 isolates), and exo U+/exo S+ type (3 isolates). 72.0% (72/100) isolates from sputum and 81.5% (44/54) isolates from blood belonged to exo U-/exo S+ genotype. Compared with those of TTSS-negative isolates, the antimicrobial resistance of TTSS-positive isolates to cefoperazone/sulbactam, ceftazidime, amikacin, and cefepime were lower (with χ² value respectively 10.1, 16.1, 9.3, 33.8, P values all below 0.01). The antimicrobial resistance to all examined drug between exo U-/exo S+ type and exo U+/exo S- type isolates was close (with χ² values from 0.08 to 2.04, P values all above 0.05). Patients detected with exo U+/exo S- positive PA isolated from sputum were significantly associated with PA infection, and they usually had history of tracheal intubation, ICU hospitalization, and combined use of drugs for anti-infection treatment. Patients detected with exo U-/exo S+ positive PA isolated from sputum were significantly associated with PA colonization, which had basic lung disease and better outcome than the former infection type.

CONCLUSIONSThe TTSS exists in most clinical isolates of PA. Detection of exo U or exo S of PA isolated from sputum is helpful for the analysis of clinical features and outcome of patients.

ADP Ribose Transferases ; genetics ; metabolism ; Bacterial Proteins ; genetics ; metabolism ; Bacterial Secretion Systems ; genetics ; Bacterial Toxins ; genetics ; metabolism ; Drug Resistance, Bacterial ; Genes, Bacterial ; Humans ; Microbial Sensitivity Tests ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; genetics ; isolation & purification ; pathogenicity ; Retrospective Studies ; Virulence

OBJECTIVETo investigate the relationship between the drug resistance of Pseudomonas aeruginosa (PA) isolated from burn patients wounds and its mobile genetic elements, including plasmid, transposon, and integron.

METHODSThirty-two strains of PA were isolated from wounds exudate of hospitalized burn patients in Ningbo No. 2 Hospital. PA drug sensitivity was determined using GNS-448 drug sensitivity card and K-B tests. The genetic markers of plasmid, transposon and integron including traA, traF, tnpA, tnpU, merA, int I 1 were amplified by PCR and verified by gene sequencing.

RESULTSDrug resistant rate of 32 PA strains to gentamicin, amikacin, cefoperazone/sulbactam, ciprofloxacin was 43.7%, 32.0%, 46.8%, 49.9%, respectively. PA drug resistant rates to piperacillin, cefotaxime, ceftazidime, cefepime, aztreonam, piperacillin/tazobactam, levofloxacin, imipenem and meropenem were all above 56.0%. Seventeen out of 32 PA strains were found to carry transposon and (or) integron genetic markers. One strain was positive for both tnpA and merA, 8 strains were positive for both merA and int I 1, 1 strain was only positive for tnpA, 2 strains were only positive for merA, and 5 strains were positive for int I 1 only.

CONCLUSIONSPA isolated from burn wounds of hospitalized patients in Ningbo No. 2 Hospital is seriously drug resistant, which may relate with its high positive rate of mobile genetic elements of transposon and (or) integron.

Anti-Bacterial Agents ; pharmacology ; Burns ; microbiology ; DNA Transposable Elements ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Integrons ; Microbial Sensitivity Tests ; Plasmids ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification

OBJECTIVETo analyze the drug resistance and drug resistance genes of imipenem-resistant Pseudomonas aeruginosa (IRPA) strains isolated from burn wards.

METHODSFrom June 2011 to June 2012, 30 strains of IRPA were isolated from wound excretion, sputum, and venous catheter attachment from burn patients hospitalized in Guangzhou Hospital of Integrated Traditional Chinese and Western Medicine. Drug resistance of the IRPA to 12 antibiotics commonly used in clinic, including ceftazidime, amikacin, ciprofloxacin, etc., was tested with K-B paper agar disk diffusion method. Metallo-β-lactamase (MBL)-producing IRPA was detected by synergism test with imipenem-2-mercaptoethanol. Plasmid of IRPA was extracted, and it was inserted into competent cells, producing transformation strains (TSs). Drug resistance of TSs to imipenem and the MBL-producing TSs were detected. The genes blaIMP, blaVIM, blaOXA-1, blaOXA-2 and blaOXA-10 of IRPA and the TSs were detected by polymerase chain reaction. The drug resistance of IRPA producing MBL or OXA enzyme was summed up.

RESULTSThe sensitive rates of the 30 strains of IRPA to the 12 antibiotics were equal to or above 60.0%. Six strains of MBL-producing IRPA were screened. Twenty-four TSs were resistant to imipenem, and 6 strains among them were MBL-producing positive. Among the 30 strains of IRPA, 6 strains and their corresponding TSs carried blaVIM; 20 strains and their corresponding TSs carried blaOXA-10; no strain was detected to carry blaIMP, blaOXA-1 or blaOXA-2. Two strains and their corresponding TSs were detected carrying both blaVIM and blaOXA-10. No significant difference of drug resistance was observed between strains producing only MBL or OXA enzyme, with the same high resistance to β-lactam antibiotics and some degree of sensitivity to aminoglycoside antibiotics. Strains producing enzymes MBL and OXA were all resistant to the 12 antibiotics.

CONCLUSIONSIRPA strains isolated from burn wards of Guangzhou Hospital of Integrated Traditional Chinese and Western Medicine are multidrug-resistant, and they mainly produce type B and D carbapenemases.

Burns ; microbiology ; Cross Infection ; microbiology ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Imipenem ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification

Bronchiectasis is a chronic lung disorder and a number of bacterial pathogens are involved. However, 30%-40% of sputum and purulent samples in good quality failed to grow any pathogenic bacteria, making it difficult to confirm the pathogen. In this study, we collected bronchoalveolar lavage fluid from a bronchiectasis patient undergoing acute exacerbation, and sent for 16S rDNA pyrosequencing by a 454 GS Junior machine. Metagenomic analysis showed the composition of bacterial community in sample was complex. More than a half of reads (51.3%) were from Pseudomonas aeruginosa. This result was corresponding with the culture result but came out 2 d earlier, which is meaningful for early diagnosis and treatment. The detection with 16S rDNA pyrosequencing technology is more sensitive and rapid than routine culture, and can detect the co-infection or symbiosis in airway, giving us a novel and convenient approach to perform rapid diagnosis.
Bronchiectasis ; microbiology ; Bronchoalveolar Lavage Fluid ; chemistry ; microbiology ; Early Diagnosis ; Female ; Humans ; Metagenome ; genetics ; Metagenomics ; methods ; Middle Aged ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; genetics ; isolation & purification ; RNA, Ribosomal, 16S ; genetics ; Time Factors