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Background: Corn is the main grain crop grown in China, and the ear shape index of corn is an important parameter for breeding new varieties, including ear length, diameter, row number of ears, row number of grains per ear, and so on. Objective: In order to solve the problem of limited field of view associated with computer detection of the corn ear shape index against a complex background, this paper proposes a panoramic splicing method for corn ears against a complex background, which can splice 10 corn ear panoramic images at the same time, to improve information collection efficiency, display comprehensive information, and support data analysis, so as to realize automatic corn seed examination. Methods: A summary of corn ear panoramic stitching methods under complex backgrounds is presented as follows: 1. a perceptual hash algorithm and histogram equalization were used to extract video frames; 2. the U-Net image segmentation model based on transfer learning was used to predict corn labels; 3. a mask preprocessing algorithm was designed; 4. a corn ear splicing positioning algorithm was designed; 5. an algorithm for irregular surface expansion was designed; 6. an image stitching method based on template matching was adopted to assemble the video frames. Results: The experimental results showed that the proposed corn ear panoramic stitching method could effectively solve the problems of virtual stitching, obvious stitching seams, and too-high similarity between multiple images. The success rate of stitching was as high as 100%, and the speed of single-corn-ear panoramic stitching was about 9.4 s, indicating important reference value for corn breeding and disease and insect detection. Discussions: Although the experimental results demonstrated the significant advantages of the panoramic splicing method for corn ear images proposed in this paper in terms of improving information collection efficiency and automating corn assessment, the method still faces certain challenges. Future research will focus on the following points: 1. addressing the issue of environmental interference caused by diseases, pests, and plant nutritional status on the measurement of corn ear parameters in order to enhance the stability and accuracy of the algorithm; 2. expanding the dataset for the U-Net model to include a wider range of corn ears with complex backgrounds, different growth stages, and various environmental conditions to improve the model's segmentation recognition rate and precision. Recently, our panoramic splicing algorithm has been deployed in practical applications with satisfactory results. We plan to continue optimizing the algorithm and more broadly promote its use in fields such as corn breeding and pest and disease detection in an effort to advance the development of agricultural automation technology. [ABSTRACT FROM AUTHOR]

As a crop with significant medicinal value and nutritional components, the market demand for bitter melon continues to grow. The diversity of bitter melon shapes has a direct impact on its market acceptance and consumer preferences, making precise identification of bitter melon germplasm resources crucial for breeding work. To address the limitations of time-consuming and less accurate traditional manual identification methods, there is a need to enhance the automation and intelligence of bitter melon phenotype detection. This study developed a bitter melon phenotype detection model named CSW-YOLO. By incorporating the ConvNeXt V2 module to replace the backbone network of YOLOv8, the model's focus on critical target features is enhanced. Additionally, the SimAM attention mechanism was introduced to compute attention weights for neurons without increasing the parameter count, further enhancing the model's recognition accuracy. Finally, WIoUv3 was introduced as the bounding box loss function to improve the model's convergence speed and positioning capabilities. The model was trained and tested on a bitter melon image dataset, achieving a precision of 94.6%, a recall of 80.6%, a mAP50 of 96.7%, and an F1 score of 87.04%. These results represent improvements of 8.5%, 0.4%, 11.1%, and 4% in precision, recall, mAP50, and F1 score, respectively, over the original YOLOv8 model. Furthermore, the effectiveness of the improvements was validated through heatmap analysis and ablation experiments, demonstrating that the CSW-YOLO model can more accurately focus on target features, reduce false detection rates, and enhance generalization capabilities. Comparative tests with various mainstream deep learning models also proved the superior performance of CSW-YOLO in bitter melon phenotype detection tasks. This research provides an accurate and reliable method for bitter melon phenotype identification and also offers technical support for the visual detection technologies of other agricultural products. [ABSTRACT FROM AUTHOR]

Since the emergence and spread of carbapenemase-producing Enterobacterales, particularly those carrying metallo-β-lactamases with 16S rRNA methyltransferases for which newly introduced antibiotics are inactive, colistin is a last resort therapy for life-threatening extensively drug-resistant infections. This requires that laboratories use an accurate and reliable method for routine colistin susceptibility testing. The aim of this study was to evaluate the performance and applicability of a colistin screening medium for detection of colistin-resistant isolates simultaneously with routine susceptibility testing. It was evaluated with fifty colistin-resistant and the same number of colistin-susceptible comparator isolates. Our results showed that all colistin-resistant isolates grew on DiaPlate™ EMB Agar + Colistin medium within the standard antibiogram period. In contrast, no growth was observed among the colistin susceptible comparators. DiaPlate™ EMB Agar + Colistin is a screening medium that can detect colistin- resistant Enterobacterales isolates when pure bacterial cultures are tested. As this method for detecting colistin-resistant isolates uses the same inoculum as the Kirby-Bauer method, the screening test for colistin resistance can be conveniently performed on clinical isolates along with routine antimicrobial susceptibility testing.

As a crop with significant medicinal value and nutritional components, the market demand for bitter melon continues to grow. The diversity of bitter melon shapes has a direct impact on its market acceptance and consumer preferences, making precise identification of bitter melon germplasm resources crucial for breeding work. To address the limitations of time-consuming and less accurate traditional manual identification methods, there is a need to enhance the automation and intelligence of bitter melon phenotype detection. This study developed a bitter melon phenotype detection model named CSW-YOLO. By incorporating the ConvNeXt V2 module to replace the backbone network of YOLOv8, the model’s focus on critical target features is enhanced. Additionally, the SimAM attention mechanism was introduced to compute attention weights for neurons without increasing the parameter count, further enhancing the model’s recognition accuracy. Finally, WIoUv3 was introduced as the bounding box loss function to improve the model’s convergence speed and positioning capabilities. The model was trained and tested on a bitter melon image dataset, achieving a precision of 94.6%, a recall of 80.6%, a mAP50 of 96.7%, and an F1 score of 87.04%. These results represent improvements of 8.5%, 0.4%, 11.1%, and 4% in precision, recall, mAP50, and F1 score, respectively, over the original YOLOv8 model. Furthermore, the effectiveness of the improvements was validated through heatmap analysis and ablation experiments, demonstrating that the CSW-YOLO model can more accurately focus on target features, reduce false detection rates, and enhance generalization capabilities. Comparative tests with various mainstream deep learning models also proved the superior performance of CSW-YOLO in bitter melon phenotype detection tasks. This research provides an accurate and reliable method for bitter melon phenotype identification and also offers technical support for the visual detection technologies of other agricultural products.

ABSTRACT Rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) is urgently needed to prevent their spread in healthcare settings. Here, we have evaluated the performance of the phenotypic methods for detection of carbapenemase production directly from bacterial cultures. A total of 99 clinical and rectal Enterobacteriaceae isolates were included (81 carrying known carbapenemase-encoding genes and 18 without carbapenemase production). All isolates were subjected to the five phenotypic tests including in-house Carba NP (iCarba NP), modified-Carba NP, E-Test MBL, modified Hodge test (MHT), and commercial combination disk test. Test results were read at different time points for iCarba NP and modified-Carba (1 min, 5 min, 15 min, 1 h and 2 h). The sensitivity and specificity of the iCarba NP were 78.87% and 100%, respectively, whereas those of the modified-Carba NP test were 95.06% and 94.44%, respectively. False-negative results were detected in four OXA-48 isolates with the use of modified-Carba NP, whereas one non-carbapenemase isolate had false-positive results. The sensitivity/specificity was 91.30%/100% and 80.25%/83.33% for the E-Test MBL and MHT, respectively. The sensitivity and specificity of the aminophenylboronic acid synergy test were 100% and 97.94%, respectively, whereas those of the dipicolinic acid synergy test were 82.61% and 96.23%, respectively. Rapid, simple, and reliable methods are needed for laboratory detection of CPE isolates to improve the detection and surveillance of these clinically relevant pathogens in an epidemiological context. We conclude that the modified-Carba NP test can be one of the reliable tests for the prediction of carbapenemase-producing bacteria.IMPORTANCEThe emergence of carbapenem resistance among Gram-negative bacteria is a serious global health threat. Here, we investigate the performance of the five phenotypic assays against carbapenemase-producing and carbapenemase-non-producing Enterobacteriaceae. Accurate and rapid detection of CPE isolates is critically required for clinical management and treatment of infections caused by these organisms. Among the five evaluated phenotypic tests, the mCNP test presented the highest sensitivity (95.06%) and, therefore, can be considered the best test to be used as a screening phenotypic methodology.

Antimicrobial Resistance (AMR) has been regarded as a major public health concern as a reason of millions of deaths. Extended-spectrum β-lactamase (ESBL) is considered as a leading factor contributing to this and limiting its treatment. Thus, ESBL producing Enterobacteriaceae should be discriminated from those having other mechanism conferring resistance. Several phenotypic methods have been evaluated for this purpose. Some of these are based on conventional method (DDST, CDT, ESBL E-test, Cica-β test) while others depend on automated systems (VITEK 1, VITEK 2, Phoenix, MicroScan). All the conventional methods have been found to be more specific, sensitive and cost effective than any of the automated system though they are easy to perform and interpret. Automated system also fails to detect ESBL in presence of other interfering enzymes such as AmpC, MBL or K1 enzyme. ESBL can be detected by using third-generation cephalosporin (cefotaxime or ceftazidime) or monobactam (aztreonam) in combination with clavulanate. AmpC can be distinguished by using cloxacillin-containing agar, fourth-generation cephalosporin (cefepime) or phenylboronic acid. MBL producers remain unaffected in presence of clavulanate but gets inhibited by carbapenems (imipenem, meropenem) in combination with EDTA. Cefpodoxime-clavulanate and ceftazidime- clavulanate combinations are reliable for K1 enzyme detection but are not suitable for distinguishing blaCTX–M1.

Antimicrobial Resistance (AMR) has been regarded as a major public health concern as a reason of millions of deaths. Extended-spectrum b-lactamase (ESBL) is considered as a leading factor contributing to this and limiting its treatment. Thus, ESBL producing Enterobacteriaceae should be discriminated from those having other mechanism conferring resistance. Several phenotypic methods have been evaluated for this purpose. Some of these are based on conventional method (DDST, CDT, ESBL E-test, Cica-b test) while others depend on automated systems (VITEK 1, VITEK 2, Phoenix, MicroScan). All the conventional methods have been found to be more specific, sensitive and cost effective than any of the automated system though they are easy to perform and interpret. Automated system also fails to detect ESBL in presence of other interfering enzymes such as AmpC, MBL or K1 enzyme. ESBL can be detected by using third-generation cephalosporin (cefotaxime or ceftazidime) or monobactam (aztreonam) in combination with clavulanate. AmpC can be distinguished by using cloxacillin-containing agar, fourth-generation cephalosporin (cefepime) or phenylboronic acid. MBL producers remain unaffected in presence of clavulanate but gets inhibited by carbapenems (imipenem, meropenem) in combination with EDTA. Cefpodoxime-clavulanate and ceftazidime- clavulanate combinations are reliable for K1 enzyme detection but are not suitable for distinguishing blaCTX-M1. [ABSTRACT FROM AUTHOR]

The extensive use of tetracycline antibiotics has led to the widespread presence of tetracycline-resistance genes in Gram-negative bacteria and this poses serious threats to human and animal health. In our previous study, we reported a method for rapid detection of Tet(X)-producers using MALDI-TOF MS. However, there have been multiple machineries involved in tetracycline resistance including efflux pump, and ribosomal protection protein. Our previous demonstrated the limitation in probing the non-Tet(X)-producing tetracycline-resistant strains. In this regard, we further developed a MALDI-TOF MS method to detect and differentiate Tet(X)-producers and non-Tet(X)-producing tetracycline-resistant strains. Test strains were incubated with tigecycline and oxytetracycline in separate tubes for 3 h and then analyzed spectral peaks of tigecycline, oxytetracycline, and their metabolite. Strains were distinguished using MS ratio for [metabolite/(metabolite+ tigecycline or oxytetracycline)]. Four control strains and 319 test strains were analyzed and the sensitivity was 98.90% and specificity was 98.34%. This was consistent with the results obtained from LC-MS/MS analysis. Interestingly, we also found that the reactive oxygen species (ROS) produced by tetracycline-susceptible strains were able to promote the degradation of oxytetracycline. Overall, the MALDITet(X)-plus test represents a rapid and reliable method to detect Tet(X)-producers, non-Tet(X)-producing tetracycline-resistant strains, and tetracycline-susceptible strains.

Background: Carbapenems have been considered as a robust antibiotic to treat extended-spectrum β-lactamases (ESBLs) in the past ten years. Carbapenems, among the β- lactams, are the most effective against gram-positive and gram-negative bacteria presenting a broad spectrum of antibacterial activity. Detection of carbapenemase-producing isolates by clinical microbiology laboratories is essential to provide targeted therapy, antimicrobial stewardship, and to update local antibiotic guidelines for clinicians. Objectives: To identify and characterize carbapenem-resistant Enterobacterales (CRE) by phenotypic and genotypic methods, and the antibiotic sensitivity patterns of CRE isolated from the different clinical samples. Methods: The samples were collected for a period of one year. Enterobacterales strains were identified through standard biochemical reactions and subjected to phenotypic screening for detection of carbapenemase, and confirmed with multiplex PCR. Antibiotic sensitivity patterns were also studied. Results: A total of 447 strains of Enterobacterales species were isolated from various clinical samples over a period of one year. Out of these, 38 (8.5%) of them showed decreased susceptibility to carbapenems including 12 Escherichia coli, 11 Klebsiella pneumonia, 1 Klebsiella oxytoca, 6 Proteus mirabilis, 2 Proteus vulgaris, and 6 Citrobacter freundii. 20 isolates of them showed the presence of carbapenemase genes in Multiplex PCR, isolates included NDM, IMP, OXA-48. Two strains showed simultaneous co-existence of two genes including NDM with OXA-48 in Klebsiella pneumonia, and NDM with IMP in Proteus mirabilis. No KPC genes were detected in our study. 97% of isolates showed sensitivity to fosfomycin (for urine samples only), 73.68% of them to tigecycline, 36.84% of them to polymyxin B, 50% to colistin, 26.31% to amikacin, 18.42% to aztreonam, 21.05% to piperacillin-tazobactam, and 10.52% to cefoperazone + sulbactam combinations. There were seven isolates of urine sample, and the sensitivity of nitrofurantoin to these isolates was 42.85%. Conclusion: The frequency of CRE was found to be low. E. coli and K. pneumoniae were the most common isolates. NDM was the commonest gene detected. Highest sensitivity was found with fosfomycin and tigecycline. [ABSTRACT FROM AUTHOR]

Yunying Wang,1 Hui Liu,2 Lijun Zhang,1 Bin Sun1 1Department of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China; 2Department of Blood Transfusion, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of ChinaCorrespondence: Bin SunDepartment of Laboratory Medicine, The Second Affiliated Hospital of Chongqing Medical University, No. 74 Linjiang Road, Yuzhong District, Chongqing, People’s Republic of ChinaTel +86 23-62887812Fax +86 23-63703244Email sunbin@cqmu.edu.cnPurpose: Infection and transmission of carbapenem-resistant Aeromonas is a serious threat to public health. Rapid and accurate detection carbapenem-resistant of these organisms is essential for reasonable treatment and infection control. This study aimed to find a simple and effective method to detect carbapenem-resistant phenotype in Aeromonas.Methods: A total of 131 clinical preserved Aeromonas strains were used in this study. The carbapenemase genes were detected by PCR. Modified carbapenem inactivation method (mCIM) in conjunction with EDTA-modified carbapenem inactivation method (eCIM) and simplified carbapenem inactivation method (sCIM) were performed to detect carbapenemases. We also designed a simple method, carbapenem inactivation method using supernatant (CIM-s), to detect the carbapenemase activity in the medium.Results: Of the 131 Aeromonas strains, 79 contained carbapenemase genes, including 68 blaCphA, 6 blaKPC-2, 2 blaNDM-1 and 3 blaKPC-2+CphA. However, routine antibiotic susceptibility testing could not completely identify carbapenemase-producing Aeromonas. In phenotypic assays, the sensitivity and specificity of mCIM were 100%. The combined mCIM and eCIM could distinguish serine carbapenemase and metallo-β-carbapenemases except co-producing organisms. The sensitivity and specificity of sCIM were 92.4% and 100%, respectively, which could not detect CphA totally. CIM-s results indicate that these carbapenemases could secrete into the medium to perform their hydrolytic activities and had a sensitivity and specificity of 97.5% and 100%, respectively.Conclusion: The combination of mCIM and eCIM can effectively detect and distinguish different types of carbapenemase in Aeromonas, and could be used as an important supplement approach to the antibiotic susceptibility testing.Keywords: Aeromonas, modified carbapenem inactivation method, carbapenemase, multidrug resistant, phenotypic detection

Introduction: Carbapenemase production is the most common mechanism of carbapenem resistance. The carbapenemases belongs to class A, class B and class D of Ambler's molecular classification. Various tests have been designed for screening and confirmation of these enzymes. The acidimetric based Carba NP (Nordmann Poirel) test is simple and detects carbapenemases within two hours. The test could not differentiate between the serine carbapenemases from Metallo ß-Lactamase (MBL). Differentiation of these two classes of enzymes will help in choosing the newer carbapenemase inhibitors like avibactam which selectively act on serine carbapenemases. Aim: To design a test that can simultaneously confirm and differentiate Amblers class A and D from class B carbapenemase enzymes among clinical strains of the Gram-Negative Bacteria (GNB). Materials and Methods: An experimental cross-sectional study was conducted between January-December 2018 on 195 strains of carbapenem resistant and 40 strains of carbapenem sensitive GNB. The carbapenemase genes were detected among all the bacteria by multiplex Polymerase Chain Reaction (PCR). The Carba M test was designed and evaluated for the detection and differentiation of class A and D from class B carbapenemases among the study isolates. Results: The Carba M test had 100% sensitivity and specificity for identification of New Delhi Metallo-ß-lactamase (NDM) and Verona Integron-encoded Metallo-ß-lactamase (VIM) enzymes. The strains which co-produced two MBL enzymes were detected with 100% sensitivity. The test had 42.85% sensitivity for the detection of Oxacillinase (OXA)-48-like enzymes. Conclusion: The Carba M test is useful in detection and simultaneous differentiation of carbapenemase content of the GNB and will help to choose appropriate carbapenemase inhibitors judiciously. [ABSTRACT FROM AUTHOR]

Abstract Background Carbapenemase-resistant Enterobacteriaceae (CRE) cause many serious infections resulting in increasing treatment cost, prolonged hospitalization, and mortality rate. Reduced expression and/or mutations of porins and the presence of carbapenemase promote Enterobacteriaceae survival under carbapenem treatments. Development of accurate methods for the detection of antimicrobial resistance is required not only for therapy but also to monitor the spread of resistant bacteria or resistance genes throughout the hospital and community. In this study, we aimed to evaluate the phenotypic methods, Modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), and EDTA-CIM (eCIM) for the detection of carbapenemase-producing Enterobacteriaceae (CPE). Results The results showed that mCIM had a sensitivity of 100% and a specificity of 100%, whereas the MHT had a sensitivity of 84.8% and a specificity of 97.8% for the 195 CRE isolates tested (105 CPE and 90 non-CPE isolates). The sensitivity of the mCIM/eCIM to detect metallo-carbapenemases in this study was 89.3% and the specificity was 98.7% as compared to the genotypic PCR detection. Conclusions These findings indicate that the mCIM combined with eCIM is useful for detecting and distinguishing different types of carbapenemase in Enterobacteriaceae.

Objectives: Carbapenem-resistant Enterobacteriaceae (CRE) are a major public-health threat. The most important mechanism of carbapenem resistance in CRE is carbapenemase production. Early identification of carbapenemase-producing Enterobacteriaceae (CPE) leads to improved clinical outcomes. This systematic review aimed to assess the accuracy and applicability of the modified Hodge test (MHT), the carbapenemase Nordmann–Poirel (Carba NP) test, the modified carbapenem inactivation method (mCIM) and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) for CPE detection. Methods: The meta-analysis included pooled sensitivity, specificity, diagnostic odds ratio, and summary receiver operating characteristic (SROC) curve and area under the curve (AUC). Results: A total of 67 studies were included in the analysis. Pooled effect sizes (95% confidence interval) of the MHT, Carba NP, mCIM and MALDI-TOF/MS, respectively, were as follows: sensitivity, 92% (87–95%), 97% (94–98%), 99% (99–100%) and 99% (96–100%); specificity, 93% (86–97%), 100% (99–100%), 99% (96–100%) and 99% (96–100%); diagnostic odds ratio, 98.156 (48.175–199.995), 1277.710 (751.391–2172.692), 3597.352 (1287.575–10000) and 1781.360 (651.827–4868.228); and AUC, 0.97, 1, 1 and 1. Conclusion: Carba NP, mCIM and MALDI-TOF/MS all demonstrated high accuracy in CPE detection, whereas the MHT is not recommended owing to some clear drawbacks. We recommend the selection of carbapenemase detection tests in the order of mCIM, Carba NP and MALDI-TOF/MS according to their simplicity, cost, and equipment and skills involved.

Abstract Background Carbapenem-resistant Klebsiella pneumoniae (CRKP) is considered as a serious global threat. CRKPs occurred only sporadically in the Second Hospital of Shanxi Medical University. Our study aimed to investigate and control the first outbreak of CRKP in our hospital occurred between October 2017 and August 2019. Methods The antimicrobial stewardship (AMS) workers have been implemented control measures properly. Clinical and epidemiological data were retrospectively collected from medical records. Carbapenemase genes were detected by modified carbapenem inactivation method (mCIM) test and the EDTA-modified carbapenem inactivation method (eCIM) test. Resistance genes were identified by polymerase chain reaction (PCR) and sequencing. Genetic relatedness was studied by multilocus sequence typing (MLST). Results During the outbreak, 31 patients were infected with CRKP isolates. 20 (64.5%) patients were infected with KPC-2 and/or NDM-1 producing K. pneumoniae. Mostly MLST-sequence types belonged to ST11 (21/31). The outbreak was two major K. pneumoniae clusters present in epidemiologically linked patients. Conclusions Setting up AMS workers is potentially a highly efficient strategy for the successful control of the outbreak. A multimodal and multidisciplinary infection control strategy proved to be crucial. The emergence of CRKP in our hospital emphasizes the importance of continuous monitoring of these isolates, which helps to limit the spread of CRKPs and improve the level of management.

Polymyxins are important therapeutic options for treating infections, mainly those caused by carbapenem-resistant Klebsiella pneumoniae. Specific chemical characteristics of polymyxins make it difficult to perform antimicrobial susceptibility testing, especially within the clinical laboratory. Here we aimed to evaluate the performance of three phenotypic methods: Rapid NP Polymyxin Test, ColiSpot test and the SuperPolymyxin medium. To accomplish this, 170 non-duplicate clinical K. pneumoniae isolates were analysed (123 colistin-resistant and 47 susceptible). The sensitivity and specificity obtained for Rapid Polymyxin NP Test, Colispot and SuperPolymyxin medium were, respectively, 90% and 94%, 74% and 100%, and 82% and 85%. Very major errors occurred more frequently in low-level colistin-resistant isolates (MICs 4 and 8 μg/mL). Rapid Polymyxin NP proved to be a method capable of identifying colistin-resistant strains in acceptable categorical agreement. However, major errors and very major errors of this method were considered unacceptable for colistin-resistance screening. Although the Colispot test is promising and easy to perform and interpret, the results did not reproduce well in the isolates tested. The colistin-containing selective medium (SuperPolymyxin) showed limitations, including quantification of mucoid colonies and poor stability. Nevertheless, Colispot and SuperPolymyxin medium methods did not present acceptable sensitivity, specificity and categorical agreement. It is essential to use analytical tools that faithfully reproduce bacterial resistance in vitro, especially in last-line drugs, such as polymyxins, when misinterpretation of a test can result in therapeutic ineffectiveness.

Antimicrobial resistance among Acinetobacter species represents one of the most critical challenges within healthcare settings. Acinetobacter baumannii primarily causes hospitalacquired infections affecting patients with prolonged hospitalization and with long-term administration of antimicrobials. A. baumannii can develop antimicrobial resistance, especially to carbapenems, the last-line of antimicrobial agents to treat serious infections. Several resistance mechanisms have been reported including antimicrobial-degrading enzymes, efflux pumps, target modification and porin deficiency which likely work synergistically. Among those, the most prevalent mechanism is enzymatic degradation by carbapenemases, ß-lactamase enzymes that are capable to hydrolyse carbapenems. Currently, spreading of carbapenem-resistant A. baumannii has been increasing worldwide. A high prevalence of A. baumannii with multidrug-resistance including carbapenems leads to conventional failure of common antibiotic therapy treatments. Therefore, accurate and rapid detection techniques of carbapenemases-producing A. baumannii are extensively required to screen and prevent the outbreak of this microorganism. Both phenotypic and genotypic methods have been developed aiming to detect carbapenemases enzymes. This review summarizes the concepts and practical approaches for phenotypic detection of this enzyme which are applicable to practise in developing countries. [ABSTRACT FROM AUTHOR]

The current study included the collection of 100 clinical samples obtained of patients reviewed in the laboratories of Ramadi hospital for women and children and Hit General Hospital and some civil laboratories within the city of Ramadi, including Bacterimea samples, Urine, abscesses, heart inflammation, wounds, rhinitis, osteoporosis, otitis, Laryngitis, sputum (35, 20, 5, 6, 7, 5, 8, 7, 4, 3) samples respectively to investigate the presence of staphylococcus aureas. The results of diagnosis of bacterial isolates showed that there were 55 bacterial isolates belonging to the S.aureus bacteria after they were grown on the culture media and examined microscopic as well as the use of some of the tests on the chemical, and the diagnosis was confirmed using the Vitek2-compact system. The diagnostic results were confirmed by the use of genetic diagnosis. The results of the phenotypic investigation were identical to the results of the genetic investigation using the polymerase chain reaction technique in terms of possessing isolates producing both hemolycin (α β), on the HIA encoding genes for the production of type α α and hlB encoded for type β production, For plasma blood on the co-α gene, and the resistance isolates of methylation on the mecA gene. [ABSTRACT FROM AUTHOR]

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is considered as a serious global threat. CRKPs occurred only sporadically in the Second Hospital of Shanxi Medical University. Our study aimed to investigate and control the first outbreak of CRKP in our hospital occurred between October 2017 and August 2019. Methods: The antimicrobial stewardship (AMS) workers have been implemented control measures properly. Clinical and epidemiological data were retrospectively collected from medical records. Carbapenemase genes were detected by modified carbapenem inactivation method (mCIM) test and the EDTA-modified carbapenem inactivation method (eCIM) test. Resistance genes were identified by polymerase chain reaction (PCR) and sequencing. Genetic relatedness was studied by multilocus sequence typing (MLST). Results: During the outbreak, 31 patients were infected with CRKP isolates. 20 (64.5%) patients were infected with KPC-2 and/or NDM-1 producing K. pneumoniae. Mostly MLST-sequence types belonged to ST11 (21/31). The outbreak was two major K. pneumoniae clusters present in epidemiologically linked patients. Conclusions: Setting up AMS workers is potentially a highly efficient strategy for the successful control of the outbreak. A multimodal and multidisciplinary infection control strategy proved to be crucial. The emergence of CRKP in our hospital emphasizes the importance of continuous monitoring of these isolates, which helps to limit the spread of CRKPs and improve the level of management. [ABSTRACT FROM AUTHOR]

Objective: We aimed to determine antibiotic susceptibility patterns of ESBL- and non-ESBL bacteria isolated from pregnant women with UTI in antenatal wards in Khartoum State, Sudan. Methods: This cross-sectional study was conducted during April-July 2016 at different hospitals in Khartoum State. Mid-stream urine samples were obtained from 150 hospitalized pregnant women and cultured on CLED (Cystine Lactose Electrolyte Deficient) agar. Microorganisms were identified using standard microbiological procedures. Isolated Gram-negative bacteria were tested for antibiotic susceptibility and ESBL screening using modified Kirby-Bauer method and Double Disc Synergy Test (DDST) respectively. Results: Urine culture revealed positive results in 33/150 (22%) and the most prevalent isolates were Gram negative bacteria (18/33, 54.5%). Among gram-negative bacteria, isolates of E. coli were the most prevalent accounting 66.6% (12/18) followed by K. pneumoniae (4/18, 22.2%) and K. oxytoca (2/18, 11.1%). ESBL was detected in 8/18 (44.4%) of the Gram-negative isolates. Of note, imipenem was the most susceptible antibiotic for ESBL-producer and non-ESBL producer Gram negative isolates, accounting 100% susceptibility for both bacterial groups. Overall susceptibility rates were also high for ciprofloxacin (13/18, 72.2%). In other hand, co-trimoxazole and amoxicillin showed high resistance pattern for ESBL-producer and non-ESBL producer isolates; 27.8%, 44.4% and 38.9%, 38.9% susceptibility rates of co-trimoxazole and amoxicillin for ESBL-producer and non-ESBL producer isolates, respectively. Conclusions: Imipenem remains the most powerful option for ESBL- and non-ESBL bacteria causing UTIs in pregnant women. However, due to tremendous increase of antibiotic-resistant, antibiotic-susceptibility testing is recommended as a routine investigation for admitted pregnant women. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the efficacy of the modified Hodge test (MHT) and Carba NP test for the detection of carbapenemase production on Gram-negative bacilli (GNB). Materials and Methods: A total of 816 well-characterized GNB isolated from various clinical samples received from both out- and hospitalized patients were included in the study. Out of those, 16.18% (132/816) were carbapenem-resistant on screening test. MHT and Carba NP test were carried out on all these carbapenem-resistant GNB isolates. Results: Out of the 132 isolates screened resistant during the study period, 75% (99/132) were positive for MHT and 86.4% (114/132) showed the presence of carbapenemase by Carba NP test. Conclusion: The advantage of the Carba NP test over MHT is that it is a rapid test where the results can be read in short time and it is easy to perform. The number of detected carbapenemase producers was significantly higher by Carba NP test though this finding can only be validated by molecular analysis of the strains.

INTRODUCTION: The aim of this study was to identify a rapid and simple phenotypic method for extended-spectrum β-lactamase (ESBL) detection in Enterobacter cloacae. METHODS: A total of 79 consecutive, non-repeated samples of E. cloacae were evaluated. Four phenotypic methods were applied for ESBL detection, results were compared to multiplex polymerase chain reaction (PCR) as the gold standard reference method: 1) ceftazidime and cefotaxime disks with and without clavulanate, both with boronic acid added; 2) disk approximation using cefepime and amoxicillin/clavulanate; 3) ESBL screening by minimum inhibitory concentration (MIC) ≥ 16µg/mL and 4) by MIC ≥ 2µg/mL for cefepime. RESULTS: Method 4 showed the best combination of sensitivity (100%) and specificity (94%). CONCLUSIONS: MIC ≥ 2µg/mL for cefepime would be very useful for the phenotypic detection of ESBL in samples of E. cloacae.

Context: Carbapenemase production is an important mechanism responsible for carbapenem resistance. Aims: Phenotypic detection and differentiation of types of carbapenemase in carbapenem resistant Enterobacteriaceae is important for proper infection control and appropriate patient management. Settings and Design: We planned a study to determine the occurrence of Class A Klebsiella pneumoniae carbapenemase (KPC type) and Class B Metallo-β-lactamase (MBL type) carbapenemase in hospital and community. Materials and Methods: Clinical isolates of Escherichia coli and Klebsiella species and simultaneously evaluate different phenotypic methods for detection of carbapenemases. Results: It was observed that 20.72% clinical isolates of E. coli and Klebsiella spp. were resistant to carbapenem on screening of which, 14.64% were E. coli and 29.69% were Klebsiella spp. Using phenotypic confirmatory tests the occurrence of carbapenemase production was found to be 87.01% in E. coli and 91.51% in Klebsiella spp. using both modified Hodge test (MHT) and combined disk test (CDT) using imipenem-ethylenediaminetetraacetic acid. Conclusions: Both MBL and KPC type carbapenemases were seen among clinical isolates of E. coli and Klebsiella spp. CDT is simple, rapid and technically less demanding procedure, which can be used in all clinical laboratories. Supplementing MHT with CDT is reliable phenotypic tests to identify the class A and class B carbapenemase producers.

The aims of this study were to describe the distribution of the most common erm genes in a collection of Norwegian Bacteroides isolates and to investigate whether the phenotypic tests for determining inducible clindamycin resistance among Bacteroides species recommended by EUCAST, NordicAST and the manufacturer of E-test ® , are effective. We investigated 175 unique Bacteroides isolates for the presence of erm (B), erm (F) and erm (G) genes, determined their minimum inhibitory concentrations (MICs) to clindamycin and categorised their susceptibility according to EUCAST breakpoints. 27 isolates were resistant to clindamycin. Furthermore, we investigated whether these recommended methods could detect inducible resistance in the Bacteroides isolates: 1) EUCAST recommendation: Dissociated resistance to erythromycin (clindamycin susceptible with erythromycin MIC > 32 mg/L), 2) NordicAST recommendation: Double disk diffusion test (DDD) or 3) Manufacturer of E-test ® ’s recommendation: prolonged incubation of clindamycin E-test ® for 48 h. erm genes were detected in 30 (17%, 95% CI 12%–23%) of 175 Bacteroides isolates with erm (F) as the dominating gene. There were six (4%, 95% CI 1%–7%) of 148 clindamycin susceptible isolates harbouring erm genes, they were considered inducibly resistant to clindamycin. None of the methods for phenotypic detection of inducible clindamycin resistance performed satisfactory with sensitivities of 33%, 17% and 0% and specificities of 90%, 99% and 97% for dissociated resistance, DDD and prolonged incubation of clindamycin E-test ® , respectively. In our view, the scientific basis for investigating every Bacteroides isolate for inducible resistance to clindamycin is weak. Molecular detection of erm genes may prove a better option than the phenotypic methods we evaluated. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the efficacy of the modified Hodge test (MHT) and Carba NP test for the detection of carbapenemase production on Gram-negative bacilli (GNB). Materials and Methods: A total of 816 well-characterized GNB isolated from various clinical samples received from both out- and hospitalized patients were included in the study. Out of those, 16.18% (132/816) were carbapenem-resistant on screening test. MHT and Carba NP test were carried out on all these carbapenem-resistant GNB isolates. Results: Out of the 132 isolates screened resistant during the study period, 75% (99/132) were positive for MHT and 86.4% (114/132) showed the presence of carbapenemase by Carba NP test. Conclusion: The advantage of the Carba NP test over MHT is that it is a rapid test where the results can be read in short time and it is easy to perform. The number of detected carbapenemase producers was significantly higher by Carba NP test though this finding can only be validated by molecular analysis of the strains. [ABSTRACT FROM AUTHOR]

Aims: Carbapenems are usually the choice of antimicrobials in infections caused by Enterobacteriaceae bacteria-producing ESBL (extended spectrum β-lactamases) and Amp C. Resistance to carbapenems is mostly due to production of enzymes - Carbapenemases, which are divided into Ambler Classes A, B and D. Phenotypic detection and differentiation of types of Carbapenemases in carbapenem-resistant Enterobacteriaceae (CRE) is important for proper infection control and appropriate patient management. Materials and Methods: The present study done in a tertiary care hospital from North India differentiates Class A (KPC type) and B (MBL type) carbapenemases among Enterobacteriaceae isolates by simple phenotypic method that uses both the inhibitors EDTA and phenylboronic acid. Results: Total of 330 strains of Enterobacteriaceae were included in the study. Out of these 330 strains, 26 strains were resistant to carbapenems. The prevalence of CRE in our Institute is 7.87% (26/330). Conclusions: The prevalence of Enterobacteriaceae strains producing MBL type carbapenemase in our health care setup is 5.75% (19/330). None of the strains among the carbapenem-resistant bacterial isolates showed production of KPC enzyme. The need of the hour is simple, rapid and cost effective tests which will be able to identify and distinguish resistant pathogens for improved patient outcome, facilitating efficient infection control and reducing the escalation of resistance.

Emerging β-lactamase-producing-bacteria (ESBL, AmpC and carbapenemases) have become a serious problem in our community due to their startling spread worldwide and their ability to cause infections which are difficult to treat. Diagnosis of these β-lactamases is of clinical and epidemiological interest. Over the past 10 years, several methods have been developed aiming to rapidly detect these emerging enzymes, thus preventing their rapid spread. In this review, we describe the range of screening and detection methods (phenotypic, molecular and other) for detecting these β-lactamases but also whole genome sequencing as a tool for detecting the genes encoding these enzymes. [ABSTRACT FROM PUBLISHER]

Antimicrobial resistance (AMR) represents a growing public health problem worldwide. Infections with such bacteria lead to longer hospitalization times, higher healthcare costs and greater morbidity and mortality. Thus, there is a greater need for rapid detection methods in order to limit their spread. The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) are a series of epidemiologically-important microorganisms of great concern due to their high levels of resistance. This review aimed to update the background information on the ESKAPE pathogens as well as to provide a summary of the numerous phenotypic and molecular methods used to detect their AMR mechanisms. While they are usually linked to hospital acquired infections, AMR is also spreading in the veterinary and the environmental sectors. Yet, the epidemiological loop closes with patients which, when infected with such pathogens, often lack therapeutic options. Thus, it was aimed to give the article a One Health perspective. [ABSTRACT FROM AUTHOR]

Background Multidrug resistance and, in particular, carbapenem resistance is spreading worldwide at an alarming rate, comprehending a variety of bacterial species and causing both nosocomial and community acquired outbursts. Early and efficient detection of infected patients or colonized carriers are mandatory steps in infection control and prevention of multidrug resistance diffusion. The latest EUCAST guidelines for detection of carbapenemase-producing Enterobacteriaceae have set low clinical breakpoints to ensure the maximum detection sensitivity of positive samples. Current workflows involve an initial screening step for species and resistance pattern detection followed by phenotypic and/or genotypic confirmation. The aim of the present study was to assess the efficiency of six widely used and validated phenotypic assays for the detection of carbapenemases/AmpC in Enterobacteriaceae, to estimate the best workflow in the routine characterization of Enterobacteriaceae isolates. Methods A panel of 108 non-repetitive Enterobacteriaceae isolates with reduced susceptibility to carbapenems was analyzed by means of 1) Modified Hodge Test, 2) Metallo Beta Lactamase Etest, 3) Double disk test with EDTA, 4) Rosco Diagnostica KPC and MBL confirm kit (RDCK™), 5) AmpC Etest and 6) Cloxacillin inhibition test. Confirmation and validation of results was achieved by genotypic analysis. Results The most accurate identification of resistance determinants was obtained with the combined disc test (Rosco Diagnostica KPC and MBL confirm kit) which had to be coupled with the cloxacillin inhibition test for correct detection of AmpC enzymes. However, in general phenotypic tests failed to characterize isolates harboring multiple carbapenem resistance determinants, which were successfully assessed only by PCR-based analysis. Conclusions To detect and control the spread of pathogens with complicated resistance patterns, both optimized phenotypic analysis (i.e. Rosco Diagnostica KPC and MBL confirm kit coupled with the cloxacillin inhibition test) and genotypic assays are recommended in the routine diagnostic of clinical laboratories. [ABSTRACT FROM AUTHOR]

Abstract: Staphylococcus aureus remains a leading, virulent pathogen capable of expressing complex drug resistance that requires up to 2–4days for laboratory analysis. In this study, we evaluate the ability of automated microscopy of immobilized live bacterial cells to differentiate susceptible from non-susceptible responses of S. aureus isolates (MRSA/MSSA, clindamycin resistance/susceptibility and VSSA/hVISA/VISA) to an antibiotic based on the characterization of as few as 10 growing clones after 4h of growth, compared to overnight growth required for traditional culture based methods. Isolates included 131 characterized CDC isolates, 3 clinical isolates and reference strains. MRSA phenotype testing used 1h of 1μg/mL cefoxitin induction followed by 3h of 6μg/mL cefoxitin. Clindamycin susceptibility testing used 1h of induction by 0.1μg/mL erythromycin followed by 3h of 0.5μg/mL clindamycin. An automated microscopy system acquired time-lapse dark-field images, and then computed growth data for individual immobilized progenitor cells and their progeny clones while exposed to different test conditions. Results were compared to concurrent cefoxitin disk diffusion and D-test references. For CDC organisms, microscopy detected 77/77 MRSA phenotypes and 54/54 MSSA phenotypes, plus 53/56 clindamycin-resistant and 75/75 clindamycin susceptible strains. Automated microscopy was used to characterize heterogeneous and inducible resistance, and perform population analysis profiles. Microscopy-based hVISA population analysis profiles (PAPs) were included as an extended proof of concept, and successfully differentiated VSSA from hVISA and VISA phenotypes compared to plate-based PAP. [Copyright &y& Elsevier]

We have developed a phenotypic method suited to the systematic screening of resistance to colistin in E . coli , including those with the mcr -1 gene, by the absence of an inhibition zone after an application of a single drop of 8 mg/L colistin solution on a previously inoculated Mueller-Hinton agar. [ABSTRACT FROM AUTHOR]

Thirty-five Bacteroides fragilis clinical isolates with varying susceptibility to meropenem were analysed with a prototype of a double-ended Etest strip containing meropenem ± EDTA, designed for the detection of the CfiA metallo-β-lactamase. Phenotypic results obtained with this new Etest strip were related to the genotype and compared to the results of the Etest containing imipenem ± EDTA. Whereas the Etest with imipenem ± EDTA only allowed detection of isolates with high-level resistance (both MICs of imipenem and meropenem >32 mg/L), reflecting the possible underestimation of CfiA prevalence in B. fragilis, the Etest with meropenem ± EDTA proved to be more accurate, particularly for isolates with low-level carbapenem resistance, suggesting its potential for broader detection of CfiA production. [ABSTRACT FROM AUTHOR]

Strains of Enterobacteriaceae producing an extended spectrum β-lactamase have become a concern in medical bacteriology as regards both antimicrobial treatment and infection control in hospitals. Extended-spectrum β-lactamase (ESBL) detection tests should accurately discriminate between bacteria producing these enzymes and those with other mechanisms of resistance to β-lactams, e.g., broad-spectrum β-lactamases, inhibitor-resistant β-lactamases and cephalosporinase overproduction. Several phenotypic detection tests, based on the synergy between a third-generation cephalosporin and clavulanate, have been designed: the double-disk synergy test (DDST), ESBL Etests, and the combination disk method. These tests often need to be refined in order for them to detect an ESBL in some bacterial strains, such as those that also overproduce a cephalosporinase. The sensitivity of the DDST can be improved by reducing the distance between the disks of cephalosporins and clavulanate. The use of cefepime, a fourth-generation cephalosporin that is less rapidly inactivated by cephalosporinase than by ESBL, improves the detection of synergy with clavulanate when there is simultaneous stable hyperproduction of a cephalosporinase; alternatively, the cephalosporinase can be inactivated by performing phenotypic tests on a cloxacillin-containing agar. Some β-lactamases can hydrolyse both third-generation cephalosporins and carbapenems, such as the metallo-β-lactamases, which are not inhibited by clavulanate, but rather by EDTA. The production of an ESBL masked by a metallo-β-lactamase can be detected by means of double inhibition by EDTA and clavulanate. Since extended-spectrum Ambler class D oxacillinases are weakly inhibited by clavulanate and not inhibited by EDTA, their detection is difficult in the routine laboratory. [ABSTRACT FROM AUTHOR]

Detection of low-level oxacillin-resistant Staphylococcus aureus is a problem that needs special attention, particularly in relation to methicillin-resistant S. aureus (MRSA) strains in the community that belong to clonal lineage ST80. This study compared different phenotypic methods for the detection of 74 low-level oxacillin-resistant S. aureus strains (oxacillin MIC ≤1 mg/L), 46 MRSA strains (oxacillin MIC ≥2 mg/L) and 117 methicillin-susceptible S. aureus strains. Determination of microbroth dilution MICs for oxacillin was wholly unsatisfactory, and gave a limited specificity for cefoxitin. The sensitivity of disk-diffusion performed according to CLSI recommendations was 92% with an oxacillin 1-µg disk, and 96% with a cefoxitin 30-µg disk; use of a 10-µg cefoxitin disk and a semi-confluent inoculum (breakpoint for resistance <18 mm zone diameter) gave a sensitivity of 97%. When disk-diffusion was performed on IsoSensitest agar with a zone diameter breakpoint for resistance of <22 mm (as recommended by the Swedish Reference Group for Antibiotics), the sensitivity was 95%. [ABSTRACT FROM AUTHOR]

Objective: This study determined the occurrence and distribution of Extended Spectrum β-Lactamase (ESBL) genotypes of E. coli isolates in Ho Teaching Hospital, Ghana., Design: A cross-sectional study., Setting: A single centre study was conducted at Ho Teaching Hospital of Ghana., Participants: Patients who visited Ho Teaching Hospital Laboratory with the request for culture and susceptibility testing., Main Outcome Measure: Escherichia coli were isolated, and Extended-Spectrum β-Lactamase genes were detected., Results: Of the 135 isolates, 56(41.5%,95% CI: 33.1% - 50.3%) were ESBL producers. More males, 14(58.3%), produced ESBL than females, 42(37.8%). The ESBL prevalence was highest among the elderly who were 80 years and above 3(100.0%), with the least prevalence among patients within 50-59 years and 0-9 years age bracket, representing 4(25.0%) and 3(27.3%), respectively. The total prevalence of ESBL was marginally higher among out-patients (41.8% 95% CI: 31.9% - 52.2%) compared to in-patients [40.5% 95% CI: 24.8% - 57.9]. BlaTEM-1 was the predominant ESBL genotype obtained from 83.9% (47/56) of the confirmed ESBL producing isolates, with the least being TOHO-1 4(7.1%). The co-existence of 2 different ESBL genes occurred in 19(33.9%) of the isolates. The single and quadruple carriage were 16(28.6%) and 3(5.4%), respectively. The highest co-existence of the ESBL genotypes was recorded for blaTEM-1 and blaCTXM-1 15(26.8%), followed by blaTEM-1, blaCTXM-1 and blaSHV-73 [12(21.4%)]., Conclusion: The high prevalence of ESBL-producing E. coli isolates with multiple resistant gene carriage is a threat to healthcare in the study area., Funding: This research received no external funding., Competing Interests: Conflict of interest: None declared, (Copyright © The Author(s).)

Abstract: Phenotypic detection of methicillin resistance in coagulase-negative Staphylococcus (CoNS) of animal origin has been challenging due to the heterogeneous expression of mecA. To compare different phenotypic methods in predicting the mecA presence in CoNS, a total of 87 CoNS isolates from agricultural animals were analyzed in this study by agar dilution, disk diffusion, and broth microdilution. mecA was present in 81 CoNS isolates. Broth microdilution demonstrated the highest sensitivity of 100% in predicting the mecA presence, followed by 72.8% by agar dilution and 70.4% by disk diffusion. The results indicate that broth microdilution may be more suitable for predicting the presence of mecA in CoNS from animals than the other two methods, although staphylococcal species may also be a factor affecting the sensitivities of the methods as the top three staphylococcal species in this study were Staphylococcus lentus, Staphylococcus sciuri, and Staphylococcus xylosus (a total of 75 of 87). [ABSTRACT FROM AUTHOR]

Background: Carbapenemase-resistant Enterobacteriaceae (CRE) cause many serious infections resulting in increasing treatment cost, prolonged hospitalization, and mortality rate. Reduced expression and/or mutations of porins and the presence of carbapenemase promote Enterobacteriaceae survival under carbapenem treatments. Development of accurate methods for the detection of antimicrobial resistance is required not only for therapy but also to monitor the spread of resistant bacteria or resistance genes throughout the hospital and community. In this study, we aimed to evaluate the phenotypic methods, Modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), and EDTA-CIM (eCIM) for the detection of carbapenemase-producing Enterobacteriaceae (CPE). Results: The results showed that mCIM had a sensitivity of 100% and a specificity of 100%, whereas the MHT had a sensitivity of 84.8% and a specificity of 97.8% for the 195 CRE isolates tested (105 CPE and 90 non-CPE isolates). The sensitivity of the mCIM/eCIM to detect metallo-carbapenemases in this study was 89.3% and the specificity was 98.7% as compared to the genotypic PCR detection. Conclusions: These findings indicate that the mCIM combined with eCIM is useful for detecting and distinguishing different types of carbapenemase in Enterobacteriaceae. [ABSTRACT FROM AUTHOR]

The worldwide emergence and spread of antimicrobial resistance in Gram-negative bacteria are severely limiting therapeutic options and thus constitute a major public health threat. The timely accurate detection of carbapenemase producers and the determination of carbapenemase class according to the Ambler classification can guide antimicrobial therapy and facilitate infection control measures. A modified version of the carbapenemase inactivation method (CIM), mCIM, was described and approved by the CLSI in 2017. We evaluated the performance of a faster new mCIM-based assay, mCIMplus, which can detect carbapenemase activity within 8 h and characterize the carbapenemase according to the Ambler classification in 20 h. A panel of 137 isolates producing carbapenemases (GES, IMP, KPC, NDM, OXA-48, OXA-48-like, and VIM enzymes) and 22 non-carbapenemase-producing isolates was used to evaluate the performance of mCIMplus. We evaluated the detection of carbapenemase activity at 8 and 20 h. Carbapenemase class was determined, with specific inhibitors, at 20 h. The sensitivities of mCIMplus were 99.3% at 8 h and 98.5% at 20 h. Its specificity was 100% regardless of culture time. Based on a decision algorithm, this test successfully identified the carbapenemase class for 98.4% of the tested isolates (127/129). Characterization was correct for 100, 95, and 100% of Ambler class A, B, and D isolates, respectively. This test can, therefore, be used to detect carbapenemase activity within 8 h and to determine carbapenemase class within 20 h. It constitutes a very affordable (<€1 per isolate) and reliable technique requiring only basic laboratory equipment., (Copyright © 2020 American Society for Microbiology.)

Background: Infections caused by gram-negative antibiotic-resistant bacteria continue to increase. Despite recommendations by the Clinical Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) with regards to detection of antibiotic degrading enzymes secreted by these bacteria, the true prevalence of extended-spectrum β-lactamase (ESBL) and carbapenemase producers remains a difficult task to resolve. Describing of previously designed phenotypic detection assays for ESBLs and carbapenemases in a single document avails a summary that allows for multiple testing which increases the sensitivity and specificity of detection., Methods and Aims: This review, therefore, defined and classified ESBLs and carbapenemases, and also briefly described how the several previously designed phenotypic detection assays for the same should be performed., Conclusion: Extended-spectrum β-lactamase and carbapenemase detection assays, once performed correctly, can precisely discriminate between bacteria producing these enzymes and those with other mechanisms of resistance to β-lactam antibiotics., (© 2020 Aruhomukama D.)

Background Beta-lactamase enzymes-producing Enterobacteriaceae have emerged in many hospital settings resulting in poor treatment outcomes. We aimed to determine resistant patterns of Beta-lactamase enzymes among Enterobacteriaceae collected from referral hospitals in Khartoum state, Sudan. Methods A total of 168 Enterobacteriaceae recovered from clinical samples of patients during May 2014 to February 2015. Identification and susceptibility testing of the isolates were performed as per standard methods. Double-disk synergy test was applied to determine the presence of extended-spectrum β-lactamase (ESBL) production. AmpC beta-lactamases and carbapenemase were screened using AmpC disk test and the modified Hodge test, respectively. Results ESBL-producing Enterobacteriaceae represented 45.2%, with a higher rate among K. pneumoniae. AmpC beta-lactamase detected as 49.3%, with peak levels among Acinetobacter baumannii (A. baumannii) (83.3%) and Enterobacter cloacae (75%). Carbapenemase production was found among 74.5% of isolates, with high rates among A. baumannii (89%) and K. pneumoniae (78%). Overall Enterobacteriaceae, highest resistance rates were found in penicillins and cephalosporins agents. Amikacin and imipenem revealed good activities against most of the isolates, except for A. baumannii (66.7% and 75%, respectively). E. coli yielded high resistance rates for amoxicillin (98.8%), amoxicillin-clavulanic acid (93.8%), cefotaxime (93.8%), and ciprofloxacin (76.5%). Moderate resistance rates were observed among K. pneumoniae for ciprofloxacin (61.5%), nitrofurantoin (57.7%) and cefoxitin (40.4%). Conclusions ESBL, AmpC beta-lactamase and carbapenemase-producing Enterobacteriaceae are emerging and may contribute to increasing antimicrobial resistance in Sudan. Phenotypic screening of such enzymes is rapid and straightforward and should be simultaneously done and carried out routinely in our hospitals., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2020, Dirar et al.)

A variant of the modified carbapenem inactivation method (mCIM) was developed to detect carbapenemase activity directly from positive blood culture broths. The method, termed "Blood-mCIM," was evaluated using Bactec blood culture bottles (Becton, Dickinson and Company, Franklin Lakes, NJ) inoculated with 27 different carbapenemase-producing Enterobacteriaceae (CPE) isolates and 34 different non-CPE isolates. The assay was positive for all blood culture broths inoculated with CPE isolates and negative for all blood culture broths inoculated with non-CPE isolates, corresponding to a diagnostic sensitivity and specificity of 100%, respectively. This assay is inexpensive using "off the shelf" reagents, does not require centrifugation or mechanical lysis, and can be readily implemented in any clinical microbiology laboratory. The Blood-mCIM should facilitate expedient administration of antimicrobial therapy targeted toward CPE bloodstream infections and assist infection control and public health surveillance., (Copyright © 2020 American Society for Microbiology.)