beta-lactam resistance pathway. B- and T-cell epitopes of the selected OMPs were predicted using BCPred as well as Propred I and Propred (http://crdd.osdd.net/raghava/propred/), respectively. Each of these OMPs contains regions which are capable to induce B- and T-cell immune responses.CONCLUSION: Analysis acquired from this study showed that five selected OMPs have great potential for vaccine development against S. flexneri infection. The predicted immunogenic epitopes can also be used for development of peptide vaccines or multi-epitope vaccines against human shigellosis. Reverse vaccinology is a promising strategy for the discovery of potential vaccine candidates which can be used for future vaccine development against global persistent infections.]]>
Anti-Bacterial Agents ; beta-Lactam Resistance ; Computational Biology ; Dysentery, Bacillary ; Enterobacteriaceae ; Epitopes ; Epitopes, T-Lymphocyte ; Humans ; Membrane Proteins ; Membranes ; Shigella flexneri ; Shigella ; T-Lymphocytes ; Vaccines ; Vaccines, Subunit

With the abuse of antimicrobial agents in developing countries, increasing number of carbapenem-resistant Enterobacteriaceae (CRE) attracted considerable public concern. A retrospective study was conducted based on 242 CRE strains from a tertiary hospital in Hangzhou, China to investigate prevalence and drug resistance characteristics of CRE in southeast China. Bacterial species were identified. Antimicrobial susceptibility was examined by broth microdilution method or epsilometer test. Resistant β-lactamase genes were identified by polymerase chain reaction and sequencing. Genotypes were investigated by phylogenetic analysis. Klebsiella pneumoniae and Escherichia coli were the most prevalent types of species, with occurrence in 71.9% and 21.9% of the strains, respectively. All strains exhibited high resistance (> 70%) against β-lactam antibiotics, ciprofloxacin, trimethoprim-sulfamethoxazole, and nitrofurantoin but exhibited low resistance against tigecycline (0.8%) and minocycline (8.3%). A total of 123 strains harbored more than two kinds of β-lactamase genes. bla, bla, bla, and bla were the predominant genotypes, with detection rates of 60.3%, 61.6%, 43.4%, and 16.5%, respectively, and were highly identical with reference sequences in different countries, indicating potential horizontal dissemination. IMP-4 was the most frequent class B metallo-lactamases in this study. In conclusion, continuous surveillance and effective prevention should be emphasized to reduce spread of CRE.
Anti-Bacterial Agents ; therapeutic use ; Carbapenem-Resistant Enterobacteriaceae ; drug effects ; enzymology ; genetics ; China ; epidemiology ; Enterobacteriaceae Infections ; epidemiology ; microbiology ; Genotype ; Humans ; Microbial Sensitivity Tests ; Phylogeny ; Prevalence ; Retrospective Studies ; beta-Lactam Resistance ; beta-Lactamases ; genetics

The emergence and spread of carbapenems-resistant Klebsiella pneumoniae (CRKP) in burn ward is an important threat to burn management. CRKP isolates are resistant to almost all available antibiotics and are susceptible only to polymyxins and tigecycline. The mechanism of the drug resistance of CRKP is associated with the plasmid-encoded carbapenemase Klebsiella pneumoniae carbapenemase (KPC), a carbapenem-hydrolyzing β-lactamase. Antibiotics which can currently be used to treat CRKP infection include polymyxins, tigecycline, and some aminoglycosides. The efficacy of using antibiotics in combination is better than that of single-agent therapy for the treatment of CRKP infection in bloodstream. In order to control CRKP infection in burn patients, strategies for preventing CRKP dissemination in burn ward are strongly advocated.
Anti-Bacterial Agents ; therapeutic use ; Bacterial Proteins ; Burns ; drug therapy ; Carbapenems ; pharmacology ; Drug Resistance, Bacterial ; Humans ; Klebsiella Infections ; drug therapy ; microbiology ; prevention & control ; Klebsiella pneumoniae ; drug effects ; Microbial Sensitivity Tests ; Minocycline ; analogs & derivatives ; therapeutic use ; beta-Lactam Resistance ; beta-Lactamases

OBJECTIVETo analyze the distribution of Enterobacteriaceae isolated from West China Hospital, investigate the antibiotic resistance profile of Enterobacteriaceae with decreased susceptibility to carbapenems and explore the molecular mechanism.

METHODSForty-five Enterobacteriaceae strains resistant or with reduced susceptibility to carbapenems were isolated from patients in West China Hospital. The antimicrobial susceptibility and carbapenemase-producing phenotypes of the bacteria were examined and specific PCR were performed to determine the molecular mechanism.

RESULTSOf the 45 isolates, 17, 21 and 36 were resistant or intermediate strains to imipenem, meropenem and ertapenem, respectively. The majority of these isolates showed resistance to cephalosporins. The modified Hodge test resulted in the highest positivity rate (77.8%), followed by EDTA disc test (57.8%) and PBA disc test (22.2%). BlaTEM, blaSHV and blaCTX-M were detected in 60.0%, 53.3% and 15.6% of these strains with reduced susceptibility. The rate of strains carrying 2 or more genes was 44.4%, and the detection rate of blaIMP was 48.9%. BlaKPC was identified in 4 (8.9%) high-level resistant strains and confirmed to locate on the plasmid.

CONCLUSIONProduction of carbapenemase contributes to reduced susceptibility of carbapenems in Enterobacteriaceae. The presence of blaKPC, MBL and ESBL, and their possible combinations can be the main factor contributing to carbapenem resistance or reduced susceptibility in Enterobacteriaceae. The KPC-2 carbapenemase gene located on the plasmids we found in this study can cause potential horizontal transmission across strains.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; metabolism ; Carbapenems ; pharmacology ; Cephalosporins ; pharmacology ; Enterobacteriaceae ; drug effects ; enzymology ; genetics ; Gene Amplification ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; Thienamycins ; pharmacology ; beta-Lactam Resistance ; beta-Lactamases ; genetics ; metabolism ; beta-Lactams ; pharmacology

OBJECTIVETo investigate the role of AdeABC efflux pump in carbapenems resistance of Acinetobacter baumannii in light of the phenotype and genetype of the efflux pump.

METHODSThe phenotype of the efflux pump was detected in 138 clinical isolates of A.baumannii using the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The mRNA expression of pump-encoding gene adeB in the strains was detected using quantitative real-time RT-PCR.

RESULTSOf the 138 strains, 28 showed positivities for AdeABC efflux pump identified by Mueller-Hinton Broth with CCCP. Of the 39 strains resistant to meropenem, 15 (38.4%) showed positive results in CCCP assay, a rate significantly higher than that among the 99 sensitive strains (13.1%, 13/99) (X(2)=12.477(b), P=0.01). The mRNA expression of efflux pump-encoding gene adeB was detected by real-time RT-PCR at a level of 0.899∓∓1.172 in meropenem-sensitive strains, significantly lower than the level of 21.101∓∓21.443 in meropenem-resistant strains (t=4.403, P=0.000).

CONCLUSIONSEfflux plays a role in carbapenems resistance in the clinical isolates of A. baumannii. The AdeABC efflux pump may be an important factor in reducing carbapenems sensitivity in A. baumannii.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Bacterial Proteins ; genetics ; metabolism ; Carbapenems ; pharmacology ; Humans ; Membrane Transport Proteins ; genetics ; metabolism ; beta-Lactam Resistance ; genetics

OBJECTIVEThis study aimed to investigate drug resistance and genotypes of the extended spectrum β-lactamase (ESBLs) and AmpC β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolated from Uygur and Han newborns in Urumqi.

METHODSDisk diffusion test (Kirby-Bauer) was used for detecting drug resistance of 299 strains to twenty two kinds of antibiotics. Resistance genes of the ESBLs and AmpC β-lactamase-producing strains were amplified by multiplex PCR and subtypes were confirmed by DNA sequence analysis. Total 148 strains were selected with random number table and sequenced, which included TEM-, SHV-, CTX-M-1-, or CTX-M-9-positive ESBLs-producing strains and DHA-, or CIT-positive AmpC β-lactamase-producing strains. Antibiotic resistant rates were analyzed by Whonet 5.4 and statistic analysis was performed by chi-square (χ(2)) test with PEMS 3.1.

RESULTSThe antibiotic resistant rates between Uygur and Han newborns significantly differ in ESBLs-producing Klebsiella pneumoniae to Sulfamethoxazole-Trimethoprim (80.0% (40/50) and 56.0% (28/50), χ(2) = 6.6176, P = 0.0101), in ESBLs-producing Escherichia coli to Sulbactam and Cefoperazone (54.2% (32/59) and 94.0% (47/50), χ(2) = 21.4512, P = 0.0000), and in AmpC &beta;-lactamase-producing Klebsiella pneumoniae to Sulbactam and Cefoperazone (100.0% (20/20) and 72.2% (26/36), χ(2) = 6.7633, P = 0.0093) and to Amikacin (65.0% (13/20) and 25.0% (9/36), χ(2) = 8.6246, P = 0.0033). Although SHV gene of ESBLs-producing Escherichia coli was detected from Uygur newborns at only 3.4% (2/59) and not detectable from Han newborns, TEM, CTX-M-1, and CTX-M-9 group genes were all detected over 38.0% (19/50). Among the detected strains, the subtypes of TEM and CTX-M-1 were mainly TEM-1 and CTX-M-15, respectively; whereas the subtypes of SHV and CTX-M-9 included SHV-1, 2, 11, 12, 27, 61, 99 and CTX-M-9, 14, 24, 27, 65, respectively. The strains of Escherichia coli and Klebsiella pneumoniae carrying two or more kinds of ESBLs genotypes were 56.7% (42/74) - 90.0% (63/70). Two species carrying the AmpC gene in two kinds of newborns were only grouped in the subtypes of DHA-1 and CMY-44, and other subtypes were not detected at all. Moreover, TEM-positive ESBLs-producing Escherichia coli were detected from Uygur newborns at the higher rate than that from Han newborns (71.2% (42/59) and 50.0% (25/50), χ(2) = 5.1291, P = 0.0235), while there was no difference in other genotypes detected between two kinds of newborns (χ(2) < 3.7780, P > 0.05).

CONCLUSIONThere were significant differences in antibiotic resistance and genotype distribution of Klebsiella pneumoniae and Escherichia coli between two nationality newborns, and these two bacteria detected in this study carried multi-resistance genes and showed high resistant to &beta;-lactamase antibiotics.

Bacterial Proteins ; metabolism ; China ; Escherichia coli ; drug effects ; genetics ; isolation & purification ; Escherichia coli Infections ; microbiology ; Ethnic Groups ; Genotype ; Humans ; Infant, Newborn ; Klebsiella Infections ; microbiology ; Klebsiella pneumoniae ; drug effects ; genetics ; isolation & purification ; Microbial Sensitivity Tests ; beta-Lactam Resistance ; genetics ; beta-Lactamases ; metabolism

OBJECTIVETo determine the risk factors and outcomes of imipenem-resistant Acinetobacter baumannii (IRAB) bloodstream infection (BSI) cases, since there is very little publication on Acinetobacter baumannii infections from Malaysia.

METHODSA cross sectional study of 41 cases (73.2%) of imipenem-sensitive Acinetobacter baumanii (ISAB) and 15 cases (26.8%) of IRAB was conducted in a teaching hospital which was located at North-Eastern state of Malaysia.

RESULTSThere was no independent risk factor for IRAB BSI identified but IRAB BSI was significantly associated with longer bacteraemic days [OR 1.23 (95% CI 1.01, 1.50)]. Although prior use of carbepenems and cephalosporin were higher among IRAB than ISAB group, statistically they were not significant. There was no significant difference in term of outcomes between the two groups.

CONCLUSIONSAlthough statistically not significant, this analysis compliments previous publication highlighting the importance of appropriate empiric antibiotic usage in hospital especially carbepenems and need further evaluation with bigger subjects.

Acinetobacter Infections ; drug therapy ; epidemiology ; microbiology ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents ; pharmacology ; therapeutic use ; Bacteremia ; drug therapy ; epidemiology ; microbiology ; Case-Control Studies ; Cross-Sectional Studies ; Female ; Hospitals, Teaching ; Humans ; Imipenem ; pharmacology ; therapeutic use ; Malaysia ; epidemiology ; Male ; Middle Aged ; Risk Factors ; Treatment Outcome ; Young Adult ; beta-Lactam Resistance

Metallo-beta-lactamase (MBL) production usually results in high-level resistance to most beta-lactams, and a rapid spread of MBL producing major gram-negative pathogens is a matter of particular concern worldwide. However, clinical data are scarce and most studies compared MBL producer (MP) with MBL non-producer (MNP) strains which included carbapenem susceptible isolates. Therefore, we collected clinical data of patients in whom imipenem-nonsusceptible Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB) were isolated from sputum or urine, and investigated MBL production and the risk factors related with MBL acquisition. The antimicrobial susceptibility patterns were also compared between MPs and imipenem-nonsusceptible MNPs (INMNP). Among the 176 imipenem-nonsusceptible isolates, 12 MPs (6.8%) were identified. There was no identifiable risk factor that contributed to the acquisition of MPs when compared to INMNPs, and case-fatalities were not different between the two groups. The percentage of susceptible isolates was higher among MPs for piperacilin/tazobactam and fluoroquinolones while that of ceftazidime was higher in INMNPs (p < 0.05). As regards to aztreonam, which has been known to be a uniquely stable beta-lactam against MBLs, susceptibility was preserved in only two isolates (16.7%) among MPs, and was not higher than that of INMNPs (23.2%). In conclusion, the contribution of MBLs to imipenem non-susceptibility in PA/ABs isolated from sputum and urine was relatively limited, and there was no significant risk factor associated with acquisition of MPs compared with INMNPs. However, limited susceptibility to aztreonam implies that MPs may hold additional resistance mechanisms, such as extended spectrum beta-lactamases, AmpC beta-lactamases, or other non-enzymatic mechanisms.
Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents/pharmacology/therapeutic use ; Child ; Child, Preschool ; Electrophoresis, Gel, Pulsed-Field ; Female ; Gram-Negative Bacteria/drug effects/*enzymology/isolation & purification ; Gram-Negative Bacterial Infections/drug therapy/enzymology/microbiology ; Humans ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Republic of Korea ; Sputum/*microbiology ; Urine/*microbiology ; beta-Lactam Resistance ; beta-Lactamases/*metabolism

OBJECTIVETo study the risk factors of infection of extended-spectrum beta-lactamases (ESBL)-producing strains and drug resistance of Enterobacteriaceae that infected burn patients.

METHODSA retrospective study was performed on clinical information of 92 patients with Enterobacteriaceae infection in our burn unit from January 2001 to December 2008. The distribution and drug resistance of Enterobacteriaceae, and the detection rate, drug resistance of ESBL-producing strains, and its risk factors of nosocomial infection were analyzed. Data were processed with Chi-square test.

RESULTSOne hundred and nine strains of Enterobacteriaceae were isolated, with 38 (34.9%) strains of Enterobacter cloacae, 25 (22.9%) strains of Escherichia coli, 22 (20.2%) strains of Klebsiella pneumoniae, 13 (11.9%) strains of Proteus mirabilis, and 11 (10.1%) other strains of Enterobacteriaceae. Enterobacteriaceae were moderately or highly resistant to antibiotics except imipenem, resistance rate of which was less than 8.0%. ESBL-producing strains accounted for 44.0% in Escherichia coli, and 77.3% in Klebsiella pneumoniae. Drug-resistance rate of ESBL-producing strains to antibiotics was obviously higher than that of non ESBL-producing strains. Length of hospital stay longer than 20 days, and use of the third-generation cephalosporin longer than 5 days, quinolone antibiotics longer than 7 days, and topical antibiotics longer than 5 days were the risk factors of nosocomial infection caused by ESBL-producing strains, comparing with non ESBL-producing strains, the difference was statistically significant (with chi2 value respectively 5.491, 4.441, 15.186, 4.938, P values all below 0.05).

CONCLUSIONSEnterobacteriaceae strains in burn unit of our hospital are highly drug resistant, with high lactamase-producing rates, calling for intense monitor to control the risk factors that predispose the infection of ESBL-producing strains in order to lower the infection rate.

Adolescent ; Adult ; Burn Units ; Child ; Drug Resistance, Bacterial ; Enterobacteriaceae ; drug effects ; Enterobacteriaceae Infections ; epidemiology ; microbiology ; Female ; Humans ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Retrospective Studies ; Risk Factors ; Young Adult ; beta-Lactam Resistance

OBJECTIVETo investigate the occurrence and drug resistance of extended-spectrum beta-lactamases (ESBLs)-producing strains of Shigella in pediatric patients, so as to provide information for clinical treatment.

METHODA total of 59 strains of Shigella were isolated from stool specimens of hospitalized children with shigellosis from January 2004 to December 2008. The broth dilution test recommended by Clinical and Laboratory Standards Institute (CLSI) was performed to detect the ESBLs producers. Susceptibility test was carried out by agar dilution method. Escherichia coli ATCC25922 and Klebsiella pneumonia ATCC700603 were used as quality control strains.

RESULTOf the 59 isolates, 21 (35.6%) strains were identified as ESBLs producers. All of the 21 strains were detected by cefotaxime and cefotaxime/clavulanic acid, only 5 (23.8%) were detected by ceftazidime and ceftazidime/clavulanic acid. Both ESBLs and non-ESBLs producers showed high resistance to penicillins. The resistance of ESBLs-producing strains to third and fourth-generation cephalosporins, aztreonam was significantly higher than that of non-ESBLs-producing strains, as well as sulphonamides and quinolones. The drugs sensitive to ESBLs producers were imipenem, meropenem, piperacillin/tazobactam, cefoperazone/sulbactam and cefoxitin, with resistance rate of 0.0%, 0.0%, 14.3%, 9.5%, 14.3%, respectively.

CONCLUSIONThe prevalence of ESBLs-producing Shigella in pediatric patients is at a high level in this area, and the enzyme-producing strains are multidrug resistant. It is recommended that the detection of ESBLs in Shigella should be carried out by microbiological laboratories. Any of the above 5 antibiotics of low resistance should be used according to the patient's condition.

Child ; Feces ; microbiology ; Humans ; Microbial Sensitivity Tests ; Shigella ; Shigella dysenteriae ; drug effects ; isolation & purification ; beta-Lactam Resistance