Occurrence of K1 and K2 serotypes and genotypic characteristics of extended spectrumβ-lactamases-producing Klebsiella pneumoniae isolated from selected hospitals in Malaysia

Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selected hospitals in Malaysia.Methods:A total of 192 K.pneumoniae isolates were collected and subjected to antibiotic susceptibility,hypermucoviscosity test and multiplex PCR to detect the presence of K1-and K2-serotype associated genes.Multilocus sequence typing(MLST)was performed on ESBL-producing K.pneumoniae isolates presented with K1 and K2 serotypes,followed by phylogenetic analysis.Results:A total of 87 out of 192(45.3%)of the K.pneumoniae isolates collected were ESBL producers.However,only 8.3%(16/192)and 10.9%(21/192)of the total isolates were detected to carry K1-and K2-serotype associated genes,respectively.Statistical analysis showed that K1 and K2 capsular serotypes were not significantly associated with ESBL phenotype(P=0.196).However,they were significantly associated with hypervirulent,as demonstrated by the positive string test(P<0.001).MLST analysis revealed that ST23 as the predominant sequence type(ST)in the K1 serotype,while the ST in the K2 serotype is more diverse.Conclusions:Although the occurrence of ESBL-producing isolates among the hypervirulent strains was low,their coexistence warrants the need for continuous surveillance.MLST showed that these isolates were genetically heterogeneous.

Phenotypic and Genotypic Characterization of Extended Spectrum Beta-Lactamases Producing Bacteria Causing Urinary Tract Infections among Expectant Women Attending Antenatal Clinic at Ruiru Sub County Hospital, Kenya

Background: Urinary tract infection (UTI) is a bacterial infection affecting males and females but is more prevalent in expectant women. ESBLs are bacteria with enzymes that make them resistant to many antibiotics, posing a significant health challenge. This study aims to determine the characteristics of ESBL-producing bacteria causing UTIs in expectant women. Methodology: A self-administered survey was carried out;300 expectant women were recruited using a random sampling method. A questionnaire was used to collect socio-demographic information. Urine samples were collected in sterile universal bottles and processed at the JKUAT Zoology laboratory. Urine samples were analyzed using urinalysis, microscopy, culture, and sensitivity testing. ESBL-producing bacteria were identified phenotypically using the double-disc synergy test (DDST) and genotyped for specific resistant genes using PCR. Results: UTI prevalence was 32.7% (98/300). UTI was significantly associated with the history of previous UTI (OR = 0.84, p = 0.02) and multigravida (OR = 0.14 p = 0.01). UTI was common in women aged between 28-37 years in their second trimester. Bacteria isolated were E. coli 57.1% (56/98), S. aureus 21.4% (21/98) K. pneumonia 11.2% (11/98) and Proteus spp 10.4% (10/98). Bacteria antibiotic resistance patterns were E. coli-tetracycline (91.1%), sulfamethoxazole (55.4%), cefotaxime (53.4%) and augmentin (53.4%). S. aureus-sulfamethozaxole (100%) and augmentin (71.4%), K. pneumoniae-sulfame-thoxazole (72.2%) cefotaxime (63.6%), chloramphenicol and tetracycline (54.5%). Proteus spp: tetracycline (100%), nitrofurantoin (90%), cefotaxime and chloramphenicol (50%). The proportion of ESBLs bacterial producers was 37.6% (29/77) and 44.8% (13/29) possessed ESBLs resistant genes;Bla CTX-M 53.8% (7/13), Bla SHV and Bla TEM 23.1% (3/13) each, Bla OXA (0%) was not detected. Conclusion: The study revealed a high proportion of ESBLs producing bacteria responsible for UTI in expectant women. ESBLs screening, routine culture and sensitivity testing will guide on proper management and empirical treatment of UTI patients thus reducing multi-drug resistance.

Dynamic Update Scheme of Spectrum Information Based on Spectrum Opportunity Incentive in the Database-Assisted Dynamic Spectrum Management

To solve the problem of delayed update of spectrum information(SI) in the database assisted dynamic spectrum management(DB-DSM), this paper studies a novel dynamic update scheme of SI in DB-DSM. Firstly, a dynamic update mechanism of SI based on spectrum opportunity incentive is established, in which spectrum users are encouraged to actively assist the database to update SI in real time. Secondly, the information update contribution(IUC) of spectrum opportunity is defined to describe the cost of accessing spectrum opportunity for heterogeneous spectrum users, and the profit of SI update obtained by the database from spectrum allocation. The process that the database determines the IUC of spectrum opportunity and spectrum user selects spectrum opportunity is mapped to a Hotelling model. Thirdly, the process of determining the IUC of spectrum opportunities is further modelled as a Stackelberg game by establishing multiple virtual spectrum resource providers(VSRPs) in the database. It is proved that there is a Nash Equilibrium in the game of determining the IUC of spectrum opportunities by VSRPs. Finally, an algorithm of determining the IUC based on a genetic algorithm is designed to achieve the optimal IUC. The-oretical analysis and simulation results show that the proposed method can quickly find the optimal solution of the IUC, and ensure that the spectrum resource provider can obtain the optimal profit of SI update.

Correction:Brillouin scattering spectrum for liquid detection and applications in oceanography

After publication of this article1,it was brought to our at-tention that the mathematical expressions‘‰’were mis-takenly replaced by‘%’for salinities.Details are listed below.1.In the last sentence in abstract,“approximately 0.1℃and 0.5%”should be“approximately 0.1℃and 0.5‰”.

Floquet spectrum and universal dynamics of a periodically driven two-atom system

We investigate the Floquet spectrum and excitation properties of a two-ultracold-atom system with periodically driven interaction in a three-dimensional harmonic trap.The interaction between the atoms is changed by varying the s-wave scattering length in two ways,the cosine and the square-wave modulations.It is found that as the driving frequency increases,the Floquet spectrum exhibits two main features for both modulations,the accumulating and the spreading of the quasienergy levels,which further lead to different dynamical behaviors.The accumulation is associated with collective excitations and the persistent growth of the energy,while the spread indicates that the energy is bounded at all times.The initial scattering length,the driving frequency and amplitude can all significantly change the Floquet spectrum as well as the dynamics.However,the corresponding relation between them is valid universally.Finally,we propose a mechanism for selectively exciting the system to one specific state by using the avoided crossing of two quasienergy levels,which could guide preparation of a desired state in experiments.

Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) utilization.Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry.However,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed.Here,a hierarchical full-spectrum solar light utilization strategy is proposed.Based on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial photosynthesis.The space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics.This work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

Blockchain-Based MCS Detection Framework of Abnormal Spectrum Usage for Satellite Spectrum Sharing Scenario

In this paper, the problem of abnormal spectrum usage between satellite spectrum sharing systems is investigated to support multi-satellite spectrum coexistence. Given the cost of monitoring, the mobility of low-orbit satellites, and the directional nature of their signals, traditional monitoring methods are no longer suitable, especially in the case of multiple power level. Mobile crowdsensing(MCS), as a new technology, can make full use of idle resources to complete a variety of perceptual tasks. However, traditional MCS heavily relies on a centralized server and is vulnerable to single point of failure attacks. Therefore, we replace the original centralized server with a blockchain-based distributed service provider to enable its security. Therefore, in this work, we propose a blockchain-based MCS framework, in which we explain in detail how this framework can achieve abnormal frequency behavior monitoring in an inter-satellite spectrum sharing system. Then, under certain false alarm probability, we propose an abnormal spectrum detection algorithm based on mixed hypothesis test to maximize detection probability in single power level and multiple power level scenarios, respectively. Finally, a Bad out of Good(BooG) detector is proposed to ease the computational pressure on the blockchain nodes. Simulation results show the effectiveness of the proposed framework.

Periodic signal extraction of GNSS height time series based on adaptive singular spectrum analysis

Singular spectrum analysis is widely used in geodetic time series analysis.However,when extracting time-varying periodic signals from a large number of Global Navigation Satellite System(GNSS)time series,the selection of appropriate embedding window size and principal components makes this method cumbersome and inefficient.To improve the efficiency and accuracy of singular spectrum analysis,this paper proposes an adaptive singular spectrum analysis method by combining spectrum analysis with a new trace matrix.The running time and correlation analysis indicate that the proposed method can adaptively set the embedding window size to extract the time-varying periodic signals from GNSS time series,and the extraction efficiency of a single time series is six times that of singular spectrum analysis.The method is also accurate and more suitable for time-varying periodic signal analysis of global GNSS sites.

THE ABSENCE OF SINGULAR CONTINUOUS SPECTRUM FOR PERTURBED JACOBI OPERATORS

This paper is mainly about the spectral properties of a class of Jacobi operators(H_(c,b)u)(n)=c_(n)u(n+1)+c_(n-1)u(n-1)+b_(n)u(n),.where∣c_(n)−1∣=O(n^(−α))and b_(n)=O(n^(−1)).We will show that,forα≥1,the singular continuous spectrum of the operator is empty.

Microbiologic and Clinical Comparison of Patients Harboring <i>Escherichia coli</i>Blood Isolates with and without Extended-Spectrum <i>β</i>-Lactamases

The clinical and microbiologic characteristics of 34 patients with extended-spectrum β-lactamase (ESBL) positive E. coli isolated from blood were compared to 66 bacteremic patients with ESBL negative E. coli, from January 2007 through December 2009. Of the 21 ESBL positive isolates available for PCR analysis, 13 were positive for CTX-M, 8 for TEM, 4 for SHV β-lactamases, with 6 possessing multiple enzymes. Twenty of 34 (59%) ESBL-positive and 41 of 66 (62%) ESBL-negative blood isolates were considered community-associated. All but one isolate in both groups had MICs of ≤1.0 μg/ml to meropenem. However, when compared to ESBL-negative isolates, ESBL-positive isolates were more frequently resistant to levofloxacin, trimethoprim/sulfamethoxazole and had higher MICs to gentamicin, tobramycin and piperacillin/tazobactam. The use of intravenous and urinary catheters was strongly associated with the isolation of E. coli bloodstream isolates in both groups of patients. Although hospital stay was similar in both groups, appropriate therapy was given in 87% of patients with ESBL positive vs. 98% of patients with ESBL negative isolates and mortality was greater for patients with ESBL positive isolates (26% vs. 17%). Since a large proportion of E. coli blood isolates were ESBL-positive and community-associated, carbapenems should be considered as initial empiric therapy for such infections in our locale.

Wideband spectrum sensing using step-sampling based on the multipath nyquist folding receiver

Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.

Uphill or downhill?Cropland use change and its drivers from the perspective of slope spectrum

The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.

Characteristics of β-Lactamase Synthesis in E. coli and K. pneumanie Strains in Nosocomial Infections

Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.

Robust Space-Time Adaptive Track-Before-Detect Algorithm Based on Persymmetry and Symmetric Spectrum

Underwater monopulse space-time adaptive track-before-detect method,which combines space-time adaptive detector(STAD)and the track-before-detect algorithm based on dynamic programming(DP-TBD),denoted as STAD-DP-TBD,can effectively detect low-speed weak targets.However,due to the complexity and variability of the underwater environment,it is difficult to obtain sufficient secondary data,resulting in a serious decline in the detection and tracking performance,and leading to poor robustness of the algorithm.In this paper,based on the adaptive matched filter(AMF)test and the RAO test,underwater monopulse AMF-DP-TBD algorithm and RAO-DP-TBD algorithm which incorporate persymmetry and symmetric spectrum,denoted as PSAMF-DP-TBD and PS-RAO-DP-TBD,are proposed and compared with the AMF-DP-TBD algorithm and RAO-DP-TBD algorithm based on persymmetry array,denoted as P-AMF-DP-TBD and P-RAO-DP-TBD.The simulation results show that the four methods can work normally with sufficient secondary data and slightly insufficient secondary data,but when the secondary data is severely insufficient,the P-AMF-DP-TBD and P-RAO-DP-TBD algorithms has failed while the PSAMF-DP-TBD and PS-RAO-DP-TBD algorithms still have good detection and tracking capabilities.

Modified Black Widow Optimization-Based Enhanced Threshold Energy Detection Technique for Spectrum Sensing in Cognitive Radio Networks

This study develops an Enhanced Threshold Based Energy Detection approach(ETBED)for spectrum sensing in a cognitive radio network.The threshold identification method is implemented in the received signal at the secondary user based on the square law.The proposed method is implemented with the signal transmission of multiple outputs-orthogonal frequency division multiplexing.Additionally,the proposed method is considered the dynamic detection threshold adjustments and energy identification spectrum sensing technique in cognitive radio systems.In the dynamic threshold,the signal ratio-based threshold is fixed.The threshold is computed by considering the Modified Black Widow Optimization Algorithm(MBWO).So,the proposed methodology is a combination of dynamic threshold detection and MBWO.The general threshold-based detection technique has different limitations such as the inability optimal signal threshold for determining the presence of the primary user signal.These limitations undermine the sensing accuracy of the energy identification technique.Hence,the ETBED technique is developed to enhance the energy efficiency of cognitive radio networks.The projected approach is executed and analyzed with performance and comparison analysis.The proposed method is contrasted with the conventional techniques of theWhale Optimization Algorithm(WOA)and GreyWolf Optimization(GWO).It indicated superior results,achieving a high average throughput of 2.2 Mbps and an energy efficiency of 3.8,outperforming conventional techniques.

Des-Arg(9)bradykinin as a causal metabolite for autism spectrum disorder

BACKGROUND Early diagnosis and therapeutic interventions can greatly enhance the developmental trajectory of children with autism spectrum disorder(ASD).However,the etiology of ASD is not completely understood.The presence of confounding factors from environment and genetics has increased the difficulty of the identification of diagnostic biomarkers for ASD.AIM To estimate and interpret the causal relationship between ASD and metabolite profile,taking into consideration both genetic and environmental influences.METHODS A two-sample Mendelian randomization(MR)analysis was conducted using summarized data from large-scale genome-wide association studies(GWAS)including a metabolite GWAS dataset covering 453 metabolites from 7824 European and an ASD GWAS dataset comprising 18381 ASD cases and 27969 healthy controls.Metabolites in plasma were set as exposures with ASD as the main outcome.The causal relationships were estimated using the inverse variant weight(IVW)algorithm.We also performed leave-one-out sensitivity tests to validate the robustness of the results.Based on the drafted metabolites,enrichment analysis was conducted to interpret the association via constructing a protein-protein interaction network with multi-scale evidence from databases including Infinome,SwissTargetPrediction,STRING,and Metascape.RESULTS Des-Arg(9)-bradykinin was identified as a causal metabolite that increases the risk of ASD(β=0.262,SE=0.064,P_(IVW)=4.64×10^(-5)).The association was robust,with no significant heterogeneity among instrument variables(P_(MR Egger)=0.663,P_(IVW)=0.906)and no evidence of pleiotropy(P=0.949).Neuroinflammation and the response to stimulus were suggested as potential biological processes mediating the association between Des-Arg(9)bradykinin and ASD.CONCLUSION Through the application of MR,this study provides practical insights into the potential causal association between plasma metabolites and ASD.These findings offer perspectives for the discovery of diagnostic or predictive biomarkers to support clinical practice in treating ASD.

What is the prognosis of emphysematous pyelonephritis associated with extended-spectrum beta-lactamases producing microorganisms?

Objective:To describe the microbiological characteristics in emphysematous pyelonephritis(EPN),demonstrate the frequency of extended-spectrum beta-lactamase(ESBL)microorganisms,and determine if these microorganisms are associated with the prognosis of patients with EPN.Methods:We conducted a retrospective study in patients with a diagnosis of EPN in a tertiary care hospital of the northeast region of Mexico during the period from January 2011 to January 2016.Clinical variables were analyzed to determine association with the presence of ESBL-producing microorganisms.Statistical significance was set with p<0.05.Results:A total of 63 patients were included;55(87.3%)of them were females,with a median age of 55(interquartile range:45-65)years.Conservative management was indicated in 38.1%;42.9%were treated with ureteral stent;12.7%with open or percutaneous drainage;15.8%with early nephrectomy;and 9.5%with delayed nephrectomy.Reported mortality was 13(20.6%)cases;23(36.5%)cases required admission to the intensive care unit.The most frequent microorganism isolated was Escherichia coli(n=34,53.9%).ESBL microorganisms were found in 31.7%of the population.No significant association of ESBL was found with admission to the intensive care unit,or with increased mortality.Conclusions:To our knowledge,this is the first study that evaluates ESBL microorganisms as a prognostic factor in EPN.Risk factors associated with a poor prognosis in patients with EPN have been described.The microbiological factors,specifically ESBL-producing bacteria,do not seem to influence in the prognosis of these patients.

Study on the Genotype of Extended-spectrum Beta-lactamases Mediated by Plasmid in Southern China

To investigate the prevalence and genotype of extended spectrum beta-lactamases (ESBLs) mediated by plasmid in Gram-negative bacteria found in southern China, a total of 1184 clinical isolates of non-repetitive strains of Gram-negative bacteria were collected in 2001 from 5 different cities in southern China. The ESBLs-producing isolates were distinguished by means of the phenotype confirmatory test based on the NCCLS criteria and were subjected to plasmid conjugation and electroporation experiments. Those clinical isolates succeeded in plasmid transfers had undergone plasmid conjugation and electro-transformation, plasmid DNA extraction and PstⅠ digest finger-printing analysis, as well as the universal primer PCR amplification of the TEM, SHV, CTX-M, VEB, PER and SFO genes and the DNA sequencing in order to determine the genotypes of ESBLs and their plasmid locations. It was found that the incidence of the ESBLs-producing strains of Gram-negative bacteria was 14.6% (173/1184) with 67 strains of transconjugants and 11 strains of electro-transformants, in which CTX-M-14 type was 33.3% (26/78); CTX-M-3 type was 23.1% (18/78); CTX-M-9 type was 14.1% (11/78); CTX-M-5 type was 6.4% ( 5/78); CTX-M-13 type was 2.6% (2/78); SHV-5 type was 7.7% (6/78); SHV-12 type was 5.1% (4/78), SHV-2a type was 2.6% (2/78) and unidentified type was 5.1% (4/78). 29.5% of the wild strains also carried broad-spectrum beta-lactamases TEM-1 and SHV-1 types. The above mentioned ESBLs genes were located on transferable plasmids with variable sizes (from 35 to 190?kb). The CTX-M type ESBLs was characterized by high-level of resistance to cefotaxime. It concluded that the CTX-M-type was the most prevalent genotype in clinical isolates of Gram-negative bacteria in southern China, and the SHV-type ranks in the second place. TEM-, VEB-, Toho- and PER-types were not found in these isolates.

Activity of Fosfomycin in Extended-Spectrum Beta-Lactamases Producing Klebsiella pneumonae from Hospital Acquired Urinary Tract Infections

Treatment of hospital acquired urinary tract infections (UTIs) caused by extended-spectrum beta-Lactamases producing Klebsiella pneumonae is a major problem. This organism expresses a high level of resistance to many groups of antibiotics. Fosfomycin is an agent which is recommended for treatment of UTIs caused by ESBLs producers. The aim of this study is to determine the sensitivity pattern of ESBLs producing urinary K. pneumonae to antimicrobial agents including fosfomycin in patients of MUHs and determine the prevalence of fosfomycin resistance mediated by plasmid mediated fosfomycin modifying enzymes fosA, fosB and fosA3. Methods: Klebsiella pneumonae urinary isolates were collected from patients with hospital acquired UTIs in Mansoura University Hospitals (MUHs). The susceptibility pattern was determined by Kirby Baur method. Isolates resistant to extended spectrum cephalosporins were tested for ESBLs production by double disc diffusion method. Fosfomycin resistance was determined by broth dilution method. Isolates resistant to fosfomycin were tested for fosA, fosB and fosA3 by PCR. Results: A total of 128 ESBLs producing K. pneumonae isolates were collected. The highest sensitivity was to imipenem (94.5%). The lowest was to trimethoprime-sulphamethoxazole (21.8%). Co-resistance of ESBLs isolates with fosfomycin was 23.2%. Eighteen fosfomycin resistant isolates (18/30) were positive to fosA. Conclusion: ESBLs producing urinary Klebsiella pneumonae express moderate sensitivity to fosfomycin. Resistance is mainly mediated by plasmid mediated fosfomycin modifying enzymes fosA.