BACKGROUND AND OBJECTIVE

The human nasal passages host major human pathogens. Recent research suggests that the microbial communities inhabiting the epithelial surfaces of the nasal passages play a key factor in maintaining a healthy microenvironment by affecting both resistance to pathogens and immunological responses. Colonization of the nasal cavity by different pathogens such as Staphylococcus aureus and Klebsiella aerogenes, is associated with a higher postoperative infection morbidity. Povidone-iodine (PVP-I) as an antiseptic has been proven to display high antibacterial, antiviral, and antifungal properties even at low concentrations, and was shown to be effective in the control of infections to limit their impact and spread. It can be used as a topical antiseptic for skin decontamination and wound management, as a nasal spray, or as a gargle. There are different methods in testing the efficacy of potential antimicrobial suspensions. This study aimed to determine the concentration of PVP-I that is most effective in nasal decolonization using microsuspension test and colorimetric minimum inhibitory concentration (MIC) determination assays, resazurin microtiter assay (REMA), and Dey-Engley (D/E) neutralizer assay. The findings of this study will contribute to knowledge regarding the intended use of PVP-I in microbial control, particularly in bacterial infections.

Several dilutions (2.0%, 1.0%, 0.5%, 0.25%, 0.1% and 0.09%) of commercially bought 10% (10 mg per 100 ml) povidone-iodine were prepared and tested against a standardized inoculum (1x105) of Staphylococcus aureus and Klebsiella aerogenes at different contacttimes (5 seconds, 10 seconds, 30 seconds, 1 minute, and 5 minutes). Microdilution suspension test was performed to determine the log reduction per variable, while REMA and D/E neutralizer assay were used to determine the MIC. A value of greater than or equal to 5 log reduction was considered effective for microdilution suspension test. Estimates of agreement statistics were used to interpret the results of the assay in which the overall percent agreement (OPA), positive percent agreement (PPA), negative percent agreement (NPA), and Cohen’s kappa statistics were calculated.

Povidone-iodine concentration of 0.25% exhibited ?5 log reduction against K. aerogenes at the minimum contact time of 5 seconds. On the other hand,  a slightly higher PVP-I concentration was required to achieve ?5 log reduction for S. aureus at 0.5% concentration and a minimum contact time of 1 minute. There was an observed concordance of the results of REMA and D/E neutralizer as MIC colorimetric indicators, which yielded an overall test percent agreement of 90.30% (95% CI: 84.73–94.36), and a strong level of agreement (? = 0.8, pCONCLUSION

Low povidone-iodine concentrations (i.e., 0.5% against S. aureus and 0.25% against K. aerogenes) were observed to have bactericidal activity of at least 5 log reduction as rapid as the minimum contact time of 5 seconds. Furthermore, D/E and REMA, as colorimetric indicators, had comparable performance (OPA = 90.30%; ? = 0.8, p
Human ; Bacteria ; Povidone-iodine ; Microbial Sensitivity Tests ; Anti-infective Agents, Local ; Enterobacter Aerogenes ; Staphylococcus Aureus

Diabetes Mellitus ; Enterobacter cloacae ; Humans ; Maxilla ; Osteonecrosis

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) are increasingly being reported throughout the world, which is a significant problem for patient treatment and infection control. Carbapenem-resistance in Enterobacteriaceae is mainly due to carbapenem-hydrolyzing β-lactamase, which tends to spread through genetic mobile elements. Therefore, the detection of carbapenemase-producing Enterobacteriaceae (CPE) carriers is particularly important for the prevention and epidemiological monitoring of these infections. In this study, we performed surveillance cultures for CPE in patients admitted to the hospital and evaluated the prevalence of CPE. METHODS: Stool cultures were obtained from a total of 228 patients at our tertiary-care hospital between March and May 2017. Stool specimens were inoculated on ChromID CARBA agar (bioMérieux, France) and incubated for 18-24 hours. Suspicious colonies with pink or bluish-green color were screened for CPE by the modified Hodge test (MHT) and carbapenemase inhibition test (CIT). We performed PCR to detect five carbapenemase genes, bla(KPC), bla(IMP), bla(VIM), bla(NDM), and bla(OXA-48). RESULTS: Among 228 isolates, seven were suspicious for CPE: four Klebsiella pneumoniae, one Escherichia coli, one Enterobacter aerogenes, and one Serratia marcescens. Two K. pneumoniae isolates showed positive reactions in both the modified Hodge test and inhibition test with phenylboronic acid. By PCR, bla(KPC) was identified in these two K. pneumoniae isolates. CONCLUSION: Our results showed a very low prevalence (2/228, 0.9%) of CPE in our tertiary-care hospital based on surveillance culture in a recent three month period.
Agar ; Enterobacter aerogenes ; Enterobacteriaceae* ; Epidemiological Monitoring ; Escherichia coli ; Humans ; Infection Control ; Klebsiella pneumoniae ; Pneumonia ; Polymerase Chain Reaction ; Prevalence ; Serratia marcescens

BACKGROUND: From January 2014 to December 2015, 69 clones of Enterobacter cloacae showing multidrug resistance to six classes of antimicrobial agents were collected from two medical centers in Korea. METHODS: Minimum inhibitory concentrations were determined using the E-test method, and 17 genes were detected using polymerase chain reaction (PCR). The epidemiological relatedness of the strains was identified using repetitive element sequence-based PCR and multilocus sequence typing. RESULTS: The 69 E. cloacae clones produced extended spectrum β lactamase (ESBL) and AmpC and showed multidrug resistance to cefotaxime, ceftazidime, and aztreonam. We identified the following sequence types: ST56 of type VI for ESBL SHV (N=12, 17.4%); ST53, ST114, ST113, and ST550 of types I, IV, VI, and VII, respectively, for CTX-M (N=11, 15.9%); and ST668 of type III for the carbapenemase NDM gene (N=1, 1.5%). The AmpC DHA gene (N=2, 2.89%) was confirmed as ST134, although its type was not identified, whereas EBC (MIR/ACT; N=18, 26.1%) was identified as ST53, ST24, ST41, ST114, ST442, ST446, ST484, and ST550 of types V, I, III, IV, VII, and VI, respectively. The formed subclasses were bla CTX-M-3 and bla CTX-M-22 by CTX-M-1, bla CTX-M-9 and bla CTX-M-125 by CTX-M-9, bla DHA-1 by DHA, and bla MIR-7 and bla ACT-15,17,18,25,27,28 by EBC (MIR/ACT). CONCLUSIONS: There were no epidemiological relationships between the gene products and the occurrence of resistance among the strains.
Anti-Infective Agents ; Aztreonam ; Cefotaxime ; Ceftazidime ; Cloaca ; Clone Cells ; Drug Resistance, Multiple* ; Enterobacter cloacae* ; Enterobacter* ; Korea ; Methods ; Microbial Sensitivity Tests ; Multilocus Sequence Typing ; 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*

Deep neck infections (DNIs) are mainly caused by dental caries, tonsillitis, and pharyngitis; however, DNIs can also occur after head and neck trauma. A 79-year-old male patient underwent a craniectomy due to an acute subdural hematoma. The patient was unconscious and continued to have a fever, but no clear cause was found. On postoperative day 9, he suddenly showed redness and swelling on the anterior neck. Enhanced computed tomography of the pharynx revealed tracheal necrosis and an abscess in the surrounding area. An incision and drainage were performed and Enterobacter aerogenes and E. faecalis were identified. The infection was controlled after antibiotic treatment. High endotracheal tube cuff pressure was suspected as the cause of the tracheal infection. Although DNIs are difficult to predict in patients who cannot report their symptoms due to unconsciousness, prevention and rapid diagnosis are important, as DNIs have serious side effects.
Abscess ; Aged ; Brain Injuries* ; Brain* ; Dental Caries ; Diagnosis ; Drainage ; Enterobacter aerogenes ; Fever ; Head ; Hematoma, Subdural, Acute ; Humans ; Intubation, Intratracheal ; Male ; Neck ; Necrosis ; Palatine Tonsil ; Pharyngitis ; Pharynx ; Tonsillitis ; Unconsciousness

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

PURPOSE: This article analyzes the microorganisms and antibiotics susceptibility in dacryocystitis. METHODS: In this study, patients who were diagnosed with acute and chronic dacryocystitis with nasolacrimal duct obstruction were selected and underwent endoscopic endonasal dacryocystorhinostomy. Cultures were obtained from the lacrimal sac during operation from January 2008 to January 2016, and were used to analyze the microorganisms and antibiotics susceptibility. RESULTS: The 67 patients, 9 were diagnosed with acute dacryocystitis and 58 were diagnosed with chronic dacryocystitis. Among them, 64 cases showed bacterial growth (95.5%). The most frequently detected bacteria was Staphylococcus epidermidis (S. epidermidis) (33.8%), followed by Staphylococcus aureus (S. aureus) (25.4%) and Enterobacter aerogenes (18.3%). S. epidermidis had the most powerful resistance to ciprofloxacin compared to the other bacteria (58.3%, p = 0.02). Except for S. epidermidis and S. aureus, the other bacteria responded to ciprofloxacin and gentamycin. CONCLUSIONS: As a causative microorganism of dacryocystitis, S. epidermidis is becoming more prominent, and it is thought that S. epidermidis may be resistant to quinolones (i.e., broad-spectrum antibiotics). This resistance might be increasing the percentage of present S. epidermidis when viewed as a causal pathogen in dacryocystitis.
Anti-Bacterial Agents* ; Bacteria ; Ciprofloxacin ; Dacryocystitis* ; Dacryocystorhinostomy ; Enterobacter aerogenes ; Gentamicins ; Humans ; Nasolacrimal Duct ; Quinolones ; Staphylococcus aureus ; Staphylococcus epidermidis

STUDY DESIGN: A retrospective clinical review. PURPOSE: To investigate the difference in clinical manifestations and severity between polymicrobial and monomicrobial infections after spinal surgery. OVERVIEW OF LITERATURE: Surgical site infections (SSIs) after spinal surgery are a major diagnostic and therapeutic challenge for spinal surgeons. Polymicrobial infections after spinal surgery seem to result in poorer outcomes than monomicrobial infections because of complementary resistance to antibiotics. However, comparison of the clinical manifestations and severity between polymicrobial and monomicrobial infections are limited. METHODS: Sixty-seven patients with SSIs after spinal surgery were studied: 20 patients with polymicrobial infections and 47 with monomicrobial infections. Pathogenic bacteria identified were counted and classified. Age, sex, and body mass index were compared between the two groups to identify homogeneity. The groups were compared for clinical manifestations by surgical site, postoperative time to infection, infection site, incisional drainage, incisional swelling, incisional pain, neurological signs, temperature, white blood cell count, and the percentage of neutrophils. Finally, the groups were compared for severity by hospital stay, number of rehospitalizations, number of debridements, duration of antibiotics administration, number of antibiotics administered, and implant removal. RESULTS: Polymicrobial infections comprised 29.9% of SSIs after spinal surgery, and most polymicrobial infections (70.0%) were caused by two species of bacteria only. There was no difference between the groups in terms of clinical manifestations and severity. In total, 96 bacterial strains were isolated from the spinal wounds: 60 strains were gram-positive and 36 were gram-negative pathogenic bacteria. Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Enterobacter cloacae were cultured in order of the frequency of appearance. CONCLUSIONS: Most polymicrobial infections were caused by two bacterial species after spinal surgery. There was no difference in clinical manifestations or severity between polymicrobial and monomicrobial infections.
Anti-Bacterial Agents ; Bacteria ; Body Mass Index ; Coinfection ; Debridement ; Drainage ; Enterobacter cloacae ; Escherichia coli ; Humans ; Length of Stay ; Leukocyte Count ; Neutrophils ; Postoperative Complications ; Retrospective Studies* ; Spine ; Staphylococcus aureus ; Staphylococcus epidermidis ; Surgeons ; Surgical Wound Infection ; Wounds and Injuries

BACKGROUND: We compared the performance of the modified Hodge test (MHT), Triton Hodge test (THT), Carba NP test (CNPt), simplified Carba NP test (CNPt-direct), blue-Carba NP test (BCT), and carbapenem inactivation method (CIM) for rapid and accurate carbapenemase detection. METHODS: The methods were evaluated by using 256 gram-negative isolates, including 197 Enterobacteriaceae (79 Enterobacter spp., 74 Klebsiella spp., 33 Escherichia coli, 10 Citrobacter spp., and 1 Serratia marcescens), 51 Acinetobacter baumannii, and 8 Pseudomonas aeruginosa strains. The collection included 117 non-carbapenemase, 18 Klebsiella pneumoniae carbapenemases (KPC) producers, 46 New Delhi metallo-β-lactamases (NDM) producers, 11 imipenemases (IMP) producers, and 51 oxacillinases (OXA) producers, and 13 strains harboring two different carbapenemase genes. RESULTS: The specificity of the THT (91.5%) was significantly lower than other methods, each of which had 100% specificity (P<0.003). This can be attributed to the false detection of Ampler class C β-lactamases (AmpC) carriers. The CNPt-direct and CIM yielded the highest sensitivities (P<0.003), which were comparable (92.8% vs 93.5%, P>0.999). Because of improved detection of NDM carriers, THT showed significantly higher sensitivity than the MHT (84.9% vs 75.5%, P<0.001). However, poor performances in detecting OXA still influenced the sensitivities of the CNPt (66.2%) and BCT (82.0%), as well as the MHT and THT. CONCLUSIONS: CNPt-direct and CIM demonstrated the best performance for the efficient detection of carbapenemase among the six evaluated methods. Except the MHT and THT, the detection of carbapenemase-producing Enterobacteriaceae by all the other methods was acceptable, when the OXA-type carbapenemase was not prevalent.
Acinetobacter baumannii ; Citrobacter ; Enterobacter ; Enterobacteriaceae ; Escherichia coli ; Gram-Negative Bacteria* ; Klebsiella ; Klebsiella pneumoniae ; Methods* ; Neptune ; Pseudomonas aeruginosa ; Sensitivity and Specificity ; Serratia