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

OBJECTIVETo analyze the isolation and the in vitro susceptibility of P. aeruginosa to antibiotics in our burn ward.

METHODSFive hundred and thirty six burn patients admitted to our ward from 1997 to 2003 were enrolled in the study, and the wound excretion, the tips of the venous catheter, the subeschar tissue samples, and the blood samples were collected for bacterial identification and antibiotic susceptibility test with VITEK-AMS system.

RESULTSThe isolation rate of P. aeruginosa from 1997 to 2003 was 24.51%, 23.94%, 21.01%, 40.06%, 36.17%, 46.76% and 55.72%, respectively. The antibiotic effect of the third generation of Cephalosporins against the said bacteria showed a tendency to decline. The susceptibility rate to Cefoperazone, Ceftazidime and Cefotaxime were respectively 71%, 66% and 79% in 1997; 47%, 25%, 39% in 1998; 22%, 16%, 25% in 2002; The third generation cephalosporins had almost lost their antibiotic activity against P. aeruginosa in 2003, with the susceptibility rate to Cefotaxime lowered to 2%. The susceptibility rate to Imipenem from 1997 to 2003 was 76%, 33%, 45%, 11%, 41%, 31%and 4%, respectively.

CONCLUSIONThe isolation rates of P. aeruginosa were steady during the period from 1997 to 1999, and they began to increase in 2000. The bacterial resistance to antibiotics increased gradually in recent years, and the strains of P. aeruginosa had become multi-drug resistant.

Anti-Bacterial Agents ; pharmacology ; Burn Units ; Burns ; microbiology ; Drug Resistance, Multiple, Bacterial ; Humans ; In Vitro Techniques ; Microbial Sensitivity Tests ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; drug effects ; isolation & purification

OBJECTIVETo investigate the distribution of burn pathogens and their antibiotic resistance in a burn unit, so as to provide reference for clinical practice.

METHODSThree hundred and forty-eight burn patients hospitalized in our department were enrolled in this study. The pathogens isolated from the wounds, blood, venous catheter, sputum, urine, purulent discharge of wounds in these patients, and their antibiotic resistance were surveyed by retrospective analysis from Jan, 2001 to Dec, 2006.

RESULTSTotal-ly 464 strains were isolated, among which Gram negative (G-) bacilli accounted for 52.6%, Gram positive microorganisms (G+) accounted for 40.5%, and fungi accounted for 6.9%. The main pathogens were Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter species and Escherichia coli, among which Staphylococcus aureus (MRSA) was predominant (93.5%). MRSA was 100% resistant to levofloxacin, penicillium, oxacillin, and it was also resistant to other antibiotics except Vancomycin. The resistance rate of Pseudomonas aeruginosa to Cefoperazone/Sulbactam, Imipenem and cefepime were 15.8%, 36.8%, 33.3%, respectively.

CONCLUSIONStaphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter species and Escherichia coli were predominant in the burn unit,among them Staphylococcus aureus and Acinetobacter were more resistant to antibiotics.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Burn Units ; Burns ; microbiology ; Cross Infection ; microbiology ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Humans ; Pseudomonas aeruginosa ; drug effects ; isolation & purification ; Retrospective Studies ; Staphylococcus aureus ; drug effects ; isolation & purification

A nationwide antimicrobial resistance surveillance has been conducted since 1997 in Korea. In this study, susceptibility test data generated in 2004 by KONSAR group hospitals were analyzed and compared to those at a commercial laboratory. In hospitals, the rank orders of organisms in 2004 were identical to those in 2003. The most prevalent species was Staphylococcus aureus (20.2%) in hospitals, but Escherichia coli (29.7%) in the commercial laboratory. The proportions of Enterococcus faecium to all isolates of Enterococcus faecalis plus E. faecium were 47.2% in hospitals and 24.9% in the commercial laboratory. The mean resistance rates of significant antimicrobial-organism combinations in hospitals were: oxacillin-resistant S. aureus (68%), oxacillin-resistant (penicillin- nonsusceptible) Streptococcus pneumoniae (68%), vancomycin-resistant E. faecium (25%), cefotaxime-resistant E. coli (14%), ceftazidime- and cefoxitin-resistant Klebsiella pneumoniae (34% and 32%, respectively), and imipenem-resistant Acinetobacter spp. and Pseudomonas aeruginosa (17% and 24%, respectively). In conclusion, oxacillin-resistant staphylococci, expanded-spectrum cephalosporin-resistant K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa were prevalent in 2004. Increasing trends were observed for vancomycin-resistant E. faecium, cefoxitin- resistant E. coli and K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa. Certain antimicrobial- organism combinations were also prevalent among the commercial laboratory-tested strains.
Pseudomonas aeruginosa/drug effects/isolation & purification ; Microbial Sensitivity Tests ; Laboratories ; Korea ; Klebsiella pneumoniae/drug effects/isolation & purification ; Imipenem/*pharmacology ; Hospitals ; Gammaproteobacteria/*drug effects/isolation & purification ; Drug Resistance, Multiple, Bacterial ; Ceftazidime/*pharmacology ; Anti-Bacterial Agents/*pharmacology ; Acinetobacter/drug effects/isolation & purification

OBJECTIVETo analyze the distribution and drug resistance of bacteria in different wound infections and provide evidence for wound infection control in subtropical regions.

METHODSThis study involved 265 patients from 4 different departments of our hospital who experienced wound infections between July, 2007 and July, 2008. The bacterial strain distribution in the wounds and drug resistance of the bacteria were analyzed.

RESULTSAcinetobacter baumanii (39% of the total strain identified) was the most frequent bacterial strain causing infection of the burn wounds, followed by Proteus mirabilis (20%) and Pseudomonas aeruginosa (20%). E. coli infection was prevalent in the departments of general surgery (37%) and urinary surgery (64%), and Pseudomonas aeruginosa and Pseudomonas pneumonia infections were detected at the rate of 30% and 43% in the urinary surgery department, respectively. Different bacterial strains were found at similar rates around 10% in the wounds of patients undergoing traumatic surgery.

CONCLUSIONDespite that the commonly seen pathogenic bacteria in burn patients including Staphylococcus aureus have been effectively controlled by early application of antibiotics, the opportunistic pathogens such as Acinetobacter baumanii and Proteus mirabilis often survive these antibiotics, and some strains evolve to be drug-resistant and even multi-drug-resistant. E. coli infection is prevalent in general surgery and urinary surgery departments, where Staphylococcus aureus and Pseudomonas aeruginosa infections can also be found frequently. All kinds of bacteria infection are present in trauma surgery department, each found at the rate around 10%.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Adolescent ; Adult ; Burns ; complications ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Female ; Humans ; Male ; Middle Aged ; Pseudomonas aeruginosa ; drug effects ; isolation & purification ; Wound Infection ; etiology ; microbiology ; Young Adult

OBJECTIVETo study changes in the drug-resistance of Pseudomonas aeruginosa (PA) and the use of antibiotics in burn wards so as to optimize the use of antibiotic in the future.

METHODSBacteria were isolated from specimens of blood, venous catheter, stool, sputum, urine, wound tissue from 5717 patients hospitalized in our burn wards within the duration of January 2005 to December 2009. The number of specimens examined and positive rates of bacteria were calculated. Changes in constituent ratio of cocci and bacilli, spectrum of bacteria, the drug-resistance rate of PA, and the usage of antibiotics were analyzed. The number of specimens examined, constituent ratio of cocci and bacilli, drug-resistance rate were processed with chi-square test. Bivariate correlation analysis was performed between the usage of antibiotics and the drug-resistance rate.

RESULTS(1) The number of specimens examined showed no statistical difference during the five years (with rates from 73.2% to 76.1%, χ(2) = 5.583, P > 0.05), while constituent ratio of cocci and bacilli showed statistical difference (with ratios from 105:134 to 169:126, χ(2) = 14.806, P < 0.01). The positive rates of bacteria were increasing in the five years. (2) One thousand six hundred and seventy-five strains were identified during the five years from different kinds of specimens, with 29 from blood, 39 from venous catheter, 3 from stool, 157 from sputum, 13 from urine, and 1434 from wound tissue. Among them, Staphylococcus aureus accounted for 28% to 42%, PA accounted for 10% to 25%, Acinetobacter baumannii accounted for 10% to 19%, and they were the predominant strains. (3) The difference among drug-resistance rates of PA to each kind of 12 antibiotics during the five years were statistically significant (with χ(2) values from 47.911 to 308.095, P values all below 0.01). The drug-resistance rates of PA to some antibiotics showed downward trend in the former four years, including amikacin, ceftazidime, and imipenem/cilastatin, but it rebounded in the fifth year. (4) There was descending trend in usage of cefoperazone/sulbactam and levofloxacin, but vancomycin was always used widely. (5) Drug-resistance rates of PA to 7 antibiotics, including amikacin, imipenem/cilastatin, and ciprofloxacin, etc., were positively correlated with usage of various antibiotics (with r values from 0.879 to 0.978, P < 0.05 or P < 0.01).

CONCLUSIONSIn our burn wards, drug-resistant PA was prevalent. Disinfection and isolation measures, appropriate use of antibiotics, etc. can reduce PA infection.

Anti-Bacterial Agents ; therapeutic use ; Burn Units ; Burns ; drug therapy ; microbiology ; Drug Resistance, Bacterial ; drug effects ; Female ; Humans ; Male ; Pseudomonas Infections ; drug therapy ; microbiology ; Pseudomonas aeruginosa ; drug effects ; isolation & purification

The discovery of quorum sensing (QS) system and its critical role in bacterial virulence have revealed a new way to attack pathogenic bacterium. The pathogenecity of QS deletion mutants decreases significantly. Targeting bacterial QS system is a promising therapeutic approach to control infections and anti-microbial resistance. To obtain natural QS inhibitors from marine organisms, marine fungi (69 strains) were isolated from marine mollusca, and their extracts were screened using improved QSIS2 (Quorum Sensing Inhibitor Selector 2) assay and Chromobacterium violaceum CV026. To improve the efficiency of QSIS2 screening, 2,3,5-triphenyltetrazolium chloride (TTC) staining method was used. Extract from strain QY013 was found to have QS inhibitory activity. Further experiment indicated that pyocyanin in Pseudomonas aeruginosa PAOI and violacein in C. violaceum CV026 were reduced by QY013 extract, without affecting bacterial growth. Morphological and 18S rDNA sequence analysis revealed that strain QY013 was most closely related to Penicillium species. The above results suggest that active constituents from QY013 may be used as novel antimicrobial agents against bacterial infection.
Animals ; Anti-Infective Agents ; isolation & purification ; metabolism ; pharmacology ; Bacterial Physiological Phenomena ; Fungi ; isolation & purification ; physiology ; Marine Biology ; Mollusca ; microbiology ; Penicillium ; isolation & purification ; metabolism ; Pseudomonas aeruginosa ; drug effects ; metabolism ; pathogenicity ; Quorum Sensing ; drug effects ; Virulence ; drug effects

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

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 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