No abstract available.
Cerebral Ventriculitis* ; Enterobacter aerogenes* ; Enterobacter* ; Pefloxacin*

BACKGROUND: The emerging mobile colistin resistance gene, mcr-1, is an ongoing worldwide concern and an evaluation of clinical isolates harboring this gene is required in Korea. We investigated mcr-1-possessing Enterobacteriaceae among Enterobacteriaceae strains isolated in Korea, and compared the genetic details of the plasmids with those in Escherichia coli isolates from livestock. METHODS: Among 9,396 Enterobacteriaceae clinical isolates collected between 2010 and 2015, 1,347 (14.3%) strains were resistant to colistin and those were screened for mcr-1 by PCR. Colistin minimum inhibitory concentrations (MICs) were determined by microdilution, and conjugal transfer of the mcr-1-harboring plasmids was assessed by direct mating. Whole genomes of three mcr-1-positive Enterobacteriaceae clinical isolates and 11 livestock-origin mcr-1-positive E. coli isolates were sequenced. RESULTS: Two E. coli and one Enterobacter aerogenes clinical isolates carried carried IncI2 plasmids harboring mcr-1, which conferred colistin resistance (E. coli MIC, 4 mg/L; E. aerogenes MIC, 32 mg/L). The strains possessed the complete conjugal machinery except for E. aerogenes harboring a truncated prepilin peptidase. The E. coli plasmid transferred more efficiently to E. coli than to Klebsiella pneumoniae or Enterobacter cloacae recipients. Among the three bacterial hosts, the colistin MIC was the highest for E. coli owing to the higher mcr-1-plasmid copy number and mcr-1 expression levels. Ten mcr-1-positive chicken-origin E. coli strains also possessed mcr-1-harboring IncI2 plasmids closely related to that in the clinical E. aerogenes isolate, and the remaining one porcine-origin E. coli possessed an mcr-1-harboring IncX4 plasmid. CONCLUSIONS: mcr-1-harboring IncI2 plasmids were identified in clinical Enterobacteriaceae isolates. These plasmids were closely associated with those in chicken-origin E. coli strains in Korea, supporting the concept of mcr-1 dissemination between humans and livestock.
Colistin ; Enterobacter aerogenes ; Enterobacter cloacae ; Enterobacteriaceae* ; Escherichia coli* ; Escherichia* ; Genome ; Humans* ; Klebsiella pneumoniae ; Korea* ; Livestock* ; Microbial Sensitivity Tests ; Plasmids* ; Polymerase Chain Reaction

BACKGROUND: This study was conducted to evaluate the impact of the media type used for direct identification of colonies on the surveillance culture of carbapenem-resistant Enterobacteriaceae (CRE) by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). METHODS: CRE surveillance culture isolates were subjected to species identification using the MALDI Biotyper (Bruker Daltonics, Germany) for 2 months starting in March 2017. Four types of media were evaluated: blood agar (BA), Mueller Hinton agar (MH), MacConkey agar (Mac), and MacConkey agar containing imipenem of 1 µg/mL (IMP-Mac). CRE-like colonies on IMP-Mac and their subculture colonies on the other media were tested after overnight incubation and extended incubation for one additional day. The percent identification and score value were analyzed for each media types and incubation time when the identification was correct at the genus level. RESULTS: A total of 117 isolates were identified as 84 Klebsiella pneumoniae, 12 Escherichia coli, 9 Enterobacter cloacae, 5 Klebsiella oxytoca, 4 Enterobacter aerogenes, and 2 Raoultella ornithinolytica. The successful identification rates (SIR) for BA and MH were 98.3% and 97.4% (P=0.9), respectively, while those for Mac and IMP-Mac were 82.1% (P < 0.001) and 70.9% (P < 0.001), respectively. After extended incubation, SIRs were decreased to 96.6%, 96.6% (P=1.0), 61.5% (P < 0.001), and 58.1% (P < 0.001) on BA, MH, Mac, and IMP-Mac, respectively. The average score values were significantly lower for Mac (2.017±0.22) and IMP-Mac (1.978±0.24) than for BA (2.213±0.16) (P < 0.001). CONCLUSIONS: The low performance of the MALDI Biotyper applied directly to the colonies grown on Mac or IMP-Mac indicates that subculture on BA or MH is preferable before identification by MALDI-TOF MS.
Agar ; Enterobacter aerogenes ; Enterobacter cloacae ; Enterobacteriaceae* ; Escherichia coli ; Imipenem ; Klebsiella oxytoca ; Klebsiella pneumoniae ; Mass Spectrometry ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*

No abstract available.
Enterobacter cloacae* ; Enterobacter* ; Pseudomonas aeruginosa* ; Pseudomonas*

BACKGROUND: In recent years, knowledge of bacterial resistance to antimicobials has expanded in important ways. Availability of an increasing number of antibiotics allows more precise individualization of resistance phenotypes and recording susceptibility results as patterns or phenotypes is valuable for both surveillance and patient care. If the patterns of resistance to panels of related antimicrobials are considered the underlying mechanisms can often be inferred. And the inferred mechanisms make the clinician to be advised to use alternative treatment. Interpretation of resistance phenotypes is based on the comparison of clinical isolates with prototype susceptible bacteria belonging to the same species. But interpretative reading of antimicrobial susceptibility tests requires an immense knowledge of antibiotics. Such interpretative reading is best achieved by computerized expert systems. METHODS: The authors attempt to determine phenotypes for the clinically isolated strains for each class of drugs tested by the Vitek 2 systemTM(bioMerieux, Marcy I'Etoile, France) using the Advanced Expert SystemTM(AES, bioMerieux, Marcy I'Etoile, France). A total of 91, 107, 89, 65, 251, 113, 47, 33, 23, 122 and 110 isolates of Staphylococcus aureus, coagulase negative staphylococci, Enterococcus faecalis, Enterococcus facium, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Enterobacter cloacae, Enterobacter aerogenes, Pseudomonas aeruginosae and Acinetobacter baumannii, were examined respectively. RESULTS: Biological correction based on the phenotype was recommended from 2.2% of E. faecalis to 46.8% of S. marcescens and therapeutic correction, from 7.3% of A. baumannii to 60.9% of E. aerogenes. A total of 25, 26, 18, 19, 22, 22, 15, 15, 17, 19, 19 phenotypes of S. aureus, coagulase negative staphylococci, E. faecalis, E. facium, E. coli, K. pneumoniae, S. marcescens, E. cloacae, E. aerogenes, P. aeruginosa and A. baumannii, were detected respectively. Association of resistance mechanism from S. aureus, coagulase negative staphylococci, E. coli, K. pneumoniae, S. marcescens, show 10, 11, 6, 4 and 3 pairs from resistant phenotypes, respectively. CONCLUSION: Vitek AES potentially provides a tool to assist the development of antimicrobial susceptibility interpretation in the clinical microbiology laboratory. The inferred mechanisms make the clinician to be advised to use alternative treatment.
Acinetobacter baumannii ; Anti-Bacterial Agents ; Bacteria ; Cloaca ; Coagulase ; Enterobacter aerogenes ; Enterobacter cloacae ; Enterococcus ; Enterococcus faecalis ; Escherichia coli ; Expert Systems ; Klebsiella pneumoniae ; Patient Care ; Phenotype* ; Pneumonia ; Pseudomonas aeruginosa ; Serratia marcescens ; Staphylococcus aureus

BACKGROUND: In 2010, the Clinical and Laboratory Standards Institute (CLSI) revised breakpoints for cephalosporins and carbapenems and indicated that extended-spectrum beta-lactamase (ESBL) testing is no longer necessary for Enterobacteriaceae. We compared the results of the CLSI 2010 and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC breakpoints for Enterobacteriaceae producing ESBL and/or plasmid-mediated AmpC beta-lactamase (PABL). METHODS: A total of 94 well-characterized clinical isolates of Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Salmonella spp., Shigella spp., Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, and Serratia marcescens were analyzed. Of them, 57 were ESBL producers, 24 were PABL producers, and 13 were ESBL plus PABL co-producers. Broth microdilution MIC tests were performed for cefotaxime, ceftazidime, aztreonam, cefepime, and imipenem. RESULTS: Among the 94 isolates containing ESBL and/or PABL, the number of isolates that were susceptible to cefotaxime, ceftazidime, aztreonam, cefepime, and imipenem according to the CLSI 2010 vs. the EUCAST breakpoints were 4 (4.3%) vs. 4 (4.3%); 26 (27.7%) vs. 8 (8.5%); 37 (39.4%) vs. 14 (14.9%); 71 (75.5%) vs. 31 (33.0%); and 76 (80.9%) vs. 90 (95.7%), respectively. Of the 18 isolates that were not susceptible to imipenem according to the CLSI 2010 breakpoints, 13 isolates (72.2%) were P. mirabilis. CONCLUSION: The CLSI 2010 MIC breakpoints without tests to detect ESBL and/or PABL for Enterobacteriaceae could be unreliable. Thus, special tests for ESBLs and AmpC beta-lactamases are required to detect the resistance mechanisms involved.
Aztreonam ; Bacterial Proteins ; beta-Lactamases ; beta-Lactams ; Carbapenems ; Cefotaxime ; Ceftazidime ; Cephalosporins ; Citrobacter freundii ; Enterobacter aerogenes ; Enterobacter cloacae ; Enterobacteriaceae ; Escherichia coli ; Imipenem ; Klebsiella oxytoca ; Klebsiella pneumoniae ; Proteus mirabilis ; Salmonella ; Serratia marcescens ; Shigella

We report a case of symmei.rical peripheral gangrene in a 22-day-old female associated with dissem-inated intravascular coagulation, which probably occured from septicmia of Enterobacter aerogenes. The skin lesions showed well-defined blackish gangrene surrounded by purpuric patches on the whole fingertips and toes except the loft thumb. Histopathologically, there were epidermal necrosis, diffuse extravasation of RBCs, mild petivascular inflammatory infiltrates and delated and RBC-filled vessels in the dermis. But, there was no definite evidence of vasculitis. In spit,e of aggressive antibictics therapy and other supportive measrres, she died at 39th day after birth.
Dermis ; Disseminated Intravascular Coagulation* ; Enterobacter aerogenes ; Female ; Gangrene* ; Humans ; Necrosis ; Parturition ; Skin ; Thumb ; Toes ; Vasculitis

The symmetrical peripheral gangrene syndrome consists of sudden onset of symmetrical gangrene of the fingers, toes and more raely, the nose, upper lip, ear lobes, or genitalia. There is no evidence of occulusion of large vessels or vasculitis. We experienced a case of symmetrical peripheral gangrene developed in fingers and toes with disseminated intravascular coagulation in 20 day-old permature infant with sepsis by Enterobacter aerogenes. Thereafter, we presented a case with a brief review of the related literatures.
Disseminated Intravascular Coagulation* ; Ear ; Enterobacter aerogenes ; Fingers ; Gangrene* ; Genitalia ; Humans ; Infant ; Lip ; Nose ; Sepsis ; Toes ; Vasculitis

BACKGROUND: Carrying antimicrobial resistance genes is a burden to bacteria. Therefore, in the absence of antimicrobial selective pressure, susceptible bacteria are expected to replace resistant ones. The cost was reported to decrease with time, but the effect of different species of susceptible bacteria on extended-spectrum -lactamase (ESBL)-, AmpC beta-lactamase-, and VIM-2 metallo-beta-lactamase-producing gram-negative bacilli are not known. The aim of this study was to determine the effect in vitro. METHODS: Antimicrobial-susceptible and -resistant strains of Escherichia coli, Enterobacter aerogenes, Klebsiella p neumoniae, and Acinetobacter baumannii were subcultured daily in glucose limited minimal salt medium at 30degrees C and 37degrees C, and the numbers of cells (CFU/mL) were determined by culturing on Mueller-Hinton agar and MacConkey agar plates. RESULTS: Continued incubation without subculture of both individual and mixed cultures at 37degrees C showed higher counts of a ESBL-producing K. p neumoniae than a susceptible E. coli. Daily subcultures of two strains in a tube showed the counts were : ESBL-producing K. pneumoniae >susceptible E. coli; susceptible E. aerogenes >ESBL-producing K. p neumoniae; susceptible E. aerogenes >VIM-2-beta-lactamase-producing Acinetobacter baumannii. The counts were similar for susceptible K. p neumoniae and AmpC beta-lactamasehyperproducing E. aerogenes. Initial low count of a susceptible E. coli and an ESBL-producing K. p neumoniae at 30degrees C gradually increased with continued subculture. CONCLUSION: Growth of not all resistant bacteria are slower and the growth improves with continued subculture. Coexistence of a susceptible bacteria with resistant bacteria in GLMS medium both at 30degrees C and 37degrees C does not reduce the number of resistant bacteria.
Acinetobacter baumannii ; Agar ; Anti-Infective Agents* ; Bacteria ; Enterobacter aerogenes ; Escherichia coli ; Glucose ; Klebsiella ; Pneumonia

Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5'-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells of Enterobacter aerogenes DGO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced.
Cytidine ; pharmacology ; Cytidine Monophosphate ; pharmacology ; Enterobacter aerogenes ; enzymology ; Enzyme Induction ; Pentosyltransferases ; biosynthesis ; Vidarabine ; biosynthesis