Detection of mobile colistin-resistance gene variants (mcr-1 and mcr-2) in urinary tract pathogens in Bangladesh: the last resort of infectious disease management colistin efficacy is under threat.

Background: Currently, colistin-resistant pathogens emerged has become a global health concern. This study assessed the distribution of mcr-1 to mcr-5 variants with the phenotypic colistin-resistance in bacterial isolates from urinary tract infection (UTI) patients in Bangladesh.Methods: A cross-sectional study was conducted between April 2017 and March 2018 to enroll uncomplicated UTI patients, and 142 urine samples were analyzed. Uropathogens were identified using the API-20E biochemical panel and 16s rRNA gene sequencing. Polymerase chain reactions detected the mcr gene variants in the UTI isolates. The phenotypic colistin-susceptibility was determined by the Kirby-Bauer disc-diffusion method and the minimal inhibitory concentration (MIC) measurement.Results: The combined carriage of mcr-1 and mcr-2 genes in 11.4% (14/123) of urinary tract pathogens. The mcr-positive pathogens include five Escherichia coli, three Klebsiella pneumoniae, three Pseudomonas putida, two Enterobacter cloacae, and one Enterobacter hormaechei. The mcr-positive variant showed significantly higher phenotypic colistin resistance with MIC between >16 µg/mL and >128 µg/mL (p< 0.001). Over 85% of colistin-resistant isolates showed MDR phenomena.Conclusions: The emergence of the clinical MDR pathogens with resistance to a highly selective drug may lead to a lack of treatment options for the infectious diseases and spread of infection to the unaffected cohorts.

Genotypic to Phenotypic Resistance Discrepancies Identified Involving ß-Lactamase Genes, blaKPC, blaIMP, blaNDM-1, and blaVIM in Uropathogenic Klebsiella pneumoniae.

INTRODUCTION: Klebsiella pneumoniae carbapenemase (KPC) belongs to the Group-A ß-lactamases that incorporate serine at their active site and hydrolyze various penicillins, cephalosporins, and carbapenems. Metallo-beta-lactamases (MBLs) are group-B enzymes that contain one or two essential zinc ions in the active sites and hydrolyze almost all clinically available ß-lactam antibiotics. Klebsiella pneumoniae remains the pathogen with the most antimicrobial resistance to KPC and MBLs. METHODS: This research investigated the blaKPC, and MBL genes, namely, blaIMP, blaVIM, and blaNDM-1 and their phenotypic resistance to K. pneumoniae isolated from urinary tract infections (UTI) in Bangladesh. Isolated UTI K. pneumoniae were identified by API-20E and 16s rDNA gene analysis. Their phenotypic antimicrobial resistance was examined by the Kirby-Bauer disc diffusion method, followed by minimal inhibitory concentration (MIC) determination. blaKPC, blaIMP, blaNDM-1, and blaVIM genes were evaluated by polymerase chain reactions (PCR) and confirmed by sequencing. RESULTS: Fifty-eight K. pneumoniae were identified from 142 acute UTI cases. Their phenotypic resistance to amoxycillin-clavulanic acid, cephalexin, cefuroxime, ceftriaxone, and imipenem were 98.3%, 100%, 96.5%, 91.4%, 75.1%, respectively. Over half (31/58) of the isolates contained either blaKPC or one of the MBL genes. Individual prevalence of blaKPC, blaIMP, blaNDM-1, and blaVIM were 15.5% (9), 10.3% (6), 22.4% (13), and 19% (11), respectively. Of these, eight isolates (25.8%, 8/31) were found to have two genes in four different combinations. The co-existence of the ESBL genes generated more resistance than each one individually. Some isolates appeared phenotypically susceptible to imipenem in the presence of blaKPC, blaIMP, blaVIM, and blaNDM-1 genes, singly or in combination. CONCLUSION: The discrepancy of genotype and phenotype resistance has significant consequences for clinical bacteriology, precision in diagnosis, the prudent selection of antimicrobials, and rational prescribing. Heterogeneous phenotypes of antimicrobial susceptibility testing should be taken seriously to avoid inappropriate diagnostic and therapeutic decisions.

Utility of Maximum Standard Uptake Value as a Predictor for Differentiating the Invasiveness of T1 Stage Pulmonary Adenocarcinoma.

BACKGROUND: The present study was performed to investigate the maximum standardized uptake value (SUVmax) in 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to preoperatively distinguish invasive from less-invasive pulmonary adenocarcinoma. PATIENTS AND METHODS: A total of 106 patients with resectable pulmonary adenocarcinoma (≤ 3 cm) who had undergone whole-body 18F-FDG PET/CT were enrolled. The SUVmax, diameter, and consolidation/tumor (C/T) ratio of the lung tumors were measured with 18F-FDG PET/CT and regional thin-section CT. RESULTS: Of the 106 patients, 32 had adenocarcinoma in situ (AIS), 13 had minimally invasive adenocarcinoma (MIA), and 61 had invasive adenocarcinoma (IAC). IAC lesions showed greater uptake of 18F-FDG, a larger tumor diameter, and greater C/T ratios than AIS and MIA (P < .001 for all). A multivariate analysis revealed that only the SUVmax, tumor diameter, and C/T ratio were independent risk factors for tumor invasiveness (P < .05 for all). The best cutoff values for the prediction of invasiveness were 2.15 for the SUVmax, 1.36 cm for the tumor diameter, and 0.36 for the C/T ratio. The SUVmax, tumor diameter, and C/T ratio showed similar predictive sensitivity (83.6%, 82.0%, and 88.5%, respectively). However, the SUVmax showed a greater predictive specificity than the C/T ratio (93.3% vs. 73.3%, respectively; P = .011) but similar to that of the tumor diameter. The predictive sensitivity and specificity were not improved using the 3 combined parameters compared with SUVmax alone. CONCLUSION: The present study has demonstrated that the SUVmax is a good preoperative predictor for the invasiveness of pulmonary adenocarcinoma (≤ 3 cm). It will help surgeons plan low invasive treatment of preinvasive tumors.

[Combined use of thin-section CT and 18F-FDG PET/CT for characterization of solitary pulmonary nodules].

OBJECTIVE: To investigate whether fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) combined with thin-section CT improves the diagnostic performance for solitary pulmonary nodules (SPNs). METHODS: A total of 267 patients underwent examinations with 18F-FDG PET/CT and thin-section CT for evaluating the SPNs with undetermined nature, which was further confirmed by pathological examination or clinical follow-up. The performance of two diagnostic criteria based on findings in PET/CT alone (Criterion 1) and in PET/CT combined with thin-section CT (Criterion 2) were compared. RESULTS: Thin-section CT provided greater diagnostic information for SPNs in 84.2% of the patients. Compared with Criterion 1, the diagnosis based on Criterion 2 significantly increased the diagnostic sensitivity (80.4% vs 91%, P<0.01) and accuracy (76.4% vs 87.2%, P<0.01) for lung cancer. The lesion size and the CT features including lobulation, air bronchogram, and feeding vessel, but not SUVmax, were all helpful for characterizing non-solid SPNs. Thin-section CT rectified diagnostic errors in 50% (20/40) of the cancerous lesions, which had been diagnosed as benign by PET due to their low metabolism. For non-solid SPNs, Criterion 2 showed a significantly higher diagnostic sensitivity than Criterion 1 (90.0% vs 40.0%, P=0.000) but their diagnostic specificity were comparable (75.2% vs 58.3%, P=0.667). For solid nodules, the use of thin-section CT resulted in no significant improvement in the diagnostic performance (P<0.05). CONCLUSION: The combination of PET/CT and thin-section CT creates a synergistic effect for the characterization of SPNs, especially non-solid nodules.

18F-FDG super bone marrow uptake: A highly potent indicator for the malignant infiltration.

The present study was performed to investigate whether the markedly 2-deoxy-2-(fluorine-18) fluoro-D-glucose (F-FDG) uptake in the bone marrow (BM) is a presentation of malignant infiltration (MI).Super bone marrow uptake (super BMU) was used to name the markedly F-FDG uptake on BM, which was similar to or higher than that of the brain. From April 2008 to December 2015, 31 patients with such presentation were retrospectively reviewed. The F-FDG uptake was semiquantified using SUVmax and BM to cerebellum (BM/C) ratio. The origin of super BMU was diagnosed by pathology. Some blood parameters, as well as fever, were also collected and analyzed. For comparison, 106 patients with mildly and moderately uptake in BM and 20 healthy subjects were selected as the control group.Bone marrow MI was diagnosed in 93.5% (29/31) patients with super BMU, which mostly originated from acute leukemia and highly aggressive lymphoma. The super BMU group had markedly higher F-FDG uptake in the BM than those of mildly and moderately uptake, and the control subjects (all P = 0.000) and the BM/C ratio reached a high of 1.24 ±â€Š0.36. The incidence of bone marrow MI in the super BMU group was markedly higher than that of mildly and moderately uptake (93.5% vs 36.8%, P = 0.000). Based on the receiver operating characteristic analysis, when cut-off values of BM/C and SUVmax were set at 0.835 and 6.560, the diagnostic specificity for bone marrow MI reached the high levels of 91.4% and 95.7%, respectively. In 15 patients with bone marrow MI, the extra-BM malignant lesions were simultaneously detected by F-FDG PET/CT. The liver and the nasal cavity involvements were only found in the patients with lymphoma, but not in those with leukemia. A decrease of leukocyte, hemoglobin, and platelet counts was noted in 48.4%, 86.2%, and 51.5% of patients with bone marrow MI, respectively.The present study revealed that super BMU was a highly potent indicator for the bone marrow MI.

False-Positive Finding on 18F FDG PET/CT: Report of a Rare Case With Xanthogranulomatous Inflammation in the Spinal Epidural Space.

Xanthogranulomatous inflammation in the spinal epidural space is extremely rare. We report a case of a 62-year-old man with a xanthogranulomatous inflammation in the spinal epidural space mistaken for lymphoma because of its avid F FDG uptake on PET/CT. This case emphasizes the need for caution when evaluating a spinal epidural mass using F FDG PET/CT as xanthogranulomatous inflammation can induce a false-positive reading on F-FDG PET/CT.