Appendical Perforation by Infection with Extended-Spectrum Beta-Lactamase (ESBL)-Producing <i>Escherichia coli</i>: Case Report

We report the very rare case of a huge appendical abscess with extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) as the pathogen. There have been several reports of appendical infections such as appendicitis and appendical abscess caused by ESBL-producing bacteria in adults. The treatment of ESBL-producing E. coli infection is specific, and ESBL-producing bacteria have recently been reported as pathogens associated appendicitis in children. To the best of our knowledge, this is the second report of perforated appendicitis with abscess due to ESBL-producing E. coli. We discuss the diagnostic modalities and treatments for appendical abscess with ESBL-producing E. coli. and propose that the patients with perforated appendicitis and abscess formation due to ESBL-producing E. coli should be administered the antibiotic MEPM within 2 weeks to treat the abscess more effec-tively without producing other multidrug-resistant bacteria.

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.

Antibiogram of Extended-Spectrum <i>β</i>-Lactamase (ESBL) Producing <i>Escherichia coli</i>

Background: Extended-spectrum β-lactamases (ESBLs) are enzymes capable of hydrolyzing extended-spectrum cephalosporins, penicillins and monobactams but inactive against cephamycins and carbapenems. The ESBL-producing organisms are a breed of multidrug-resistant pathogens. Objectives: This study was aimed to determine the susceptibility pattern of ESBL-producing Escherichia coli to ciprofloxacin, amikacin and imipenem. Methods: A total of 75 ESBL-producing E. coli, were obtained from the tertiary care hospitals of Bangladesh and were studied for susceptibility pattern from October, 2010 to December, 2011. These isolates were identified by double disc synergy test (DDST) and were confirmed phenotypically as ESBL-producer by phenotypic confirmatory disc diffusion test (PCDDT). Minimum inhibitory concentrations (MICs) of ciprofloxacin, amikacin and imipenem among ESBL-producing E. coli were determined using agar dilution method. Results: Out of 75 DDST positive ESBL-producing E. coli, 71 (94.67%) were also positive by PCDDT. All ESBL-producing E. coli, were susceptible to imipenem. About 92.95% ESBL-producing E. coli were susceptible to amikacin but only 14.08% were susceptible to ciprofloxacin. Conclusion: In this study, ESBL-producing E. coli, showed high resistance to ciprofloxacin. Imipenem and amikacin were most effective against ESBL positive strains.

Extended-spectrum β-lactamase controversies

G.A.Jacoby 教授毕业于美国哈佛医学院,为国际知名的传染病学、微生物学和免疫学专家,曾长期担任美国麻省总医院传染病科医师,现任麻省 Lahey 医学中心传染病实验室主任,中国感染与化疗杂志特邀编委。长期以来 Jacoby 教授对细菌耐药机制有深入研究,尤其对细菌(肺炎克雷伯菌、大肠埃希菌等)产生质粒介导的超广谱β内酰胺酶(ESBL)以及喹诺酮类的耐药机制研究。曾发表多篇有关上述专题的权威性论著。此次本刊特邀 Jacoby 教授撰写有关 ESBL 的新进展,文中阐述目前 ESBLs 除通常所指质粒介导β内酰胺酶中扩大了酶水解的底物谱导致细菌对头孢噻肟、头孢他啶、氨曲南等抗生素耐药外,还包括许多具有不同特点的β内酰胺酶,其中某些酶产自共生菌。除 ESBL 外,AmpC 酶和各种碳青霉烯β内酰胺酶也可导致细菌对上述抗生素耐药,因此临床微生物实验室准确检出和鉴别各种β内酰胺酶,对于临床选用适宜的抗茵药十分重要。美国 CLSI(过去称为 NCCLS)推荐采用两步法(筛选及确证)检测细菌产 ESBL;但有的学者认为测定抗茵药物对细菌的 MIC,如用药后 T>MIC 在50%以上即可达到满意疗效,无需检测细菌是否产 ESBL。目前认为碳青霉烯类抗生素治疗产 ESBL 菌感染的疗效最为满意,但由此可能引起细菌对该类药物耐药,值得关注。采用大剂量头孢吡肟或哌拉西林-三唑巴坦治疗产ESBL 菌感染是否有效尚有争论,临床上对β内酰胺类最为耐药的菌株往往对几乎所有现用抗菌药耐药。黏菌素(或多黏菌素 B)曾成功的用于治疗此种多重耐药菌感染。此外替莫西林(temocillin,一种对β内酰胺酶稳定的青霉素类)与替加环素(tigecvcline,为米诺环素衍生物)体外对产 ESBL 菌有抗菌作用,但尚无临床研究资料。

Effect of "Fuzheng Qingre Tonglin" prescription on rats with complicated urinary tract infection caused by ESBLs-producing Escherichia coli

Objective: To observe the effect of traditional Chinese medicine "Fuzheng Qingre Tonglin"prescription on rats with complicated urinary tract infection caused by extended-spectrumβ-lactamases (ESBLs)-producing Escherichia coli and its possible mechanism. Methods:Specific-pathogen-free female SD rats with 7-9 weeks old were randomly divided into model group, levofloxacin group, low-dose Fuzheng Qingre Tonglin group, high-dose Fuzheng Qingre Tonglin group, levofloxacin+Fuzheng Qingre Tonglin group (n=8 in each above group), and also there was a control group with 5 rats. Each group was administered intragastrically 2 days after model establishment for 14 consecutive days. The general condition of the rats was observed. Renal pathological changes were observed by light microscopy under hematoxylin-eosin staining. The number of white blood cells and the percentage of neutral particles (NEUT%) were detected. ELISA was used for the determination of C-reactive protein (CRP), CD4+, CD8+ in the blood, and secretory immunoglobulin A (SIgA), N-acetyl-β-D-glucosidase (NAG) molecules in urine. Results: There were a large number of inflammatory cells in the kidney of the model group and the levofloxacin group. The inflammatory cells in the treatment group were significantly reduced. The NEUT% and CRP in the blood of each treatment group and the NAG in the urine were significantly lower than those in the model group (P<0.05), except levofloxacin group. Compared with the model group, except for the levofloxacin group, serum CD4 concentration and CD4/CD8 ratio in the other treatment groups were significantly decreased, and CD8 molecules were significantly increased (P<0.05). Conclusion: "Fuzheng Qingre Tonglin" can alleviate systemic and local inflammation of complicated urinary tract infections in rats. It may also have the effect of re-sensing the insensitive antibacterial drug to bacteria and may have the function of regulating immune function and protecting kidney function in rats.

Unravelling Antimicrobial Resistance Phenotypes and Carriage of Extended-Spectrum β-Lactamase Genes in Escherichia coli Isolated from Dairy Farms in Kiambu County, Kenya

The use of antibiotics for prophylaxis and growth enhancement in livestock farming is on the increase globally. This practice has led to the emergence and spread of antimicrobial-resistant bacteria in livestock. Only limited research has been done to establish the role of cattle farming in antimicrobial resistance. The current study sought to establish the carriage of multi-drug resistance and extended-spectrum beta-lactamase genes in Escherichia coli from farmers, their cattle, and cattle slurry within Kiambu County. A total of 286 (81%) E. coli isolates were recovered from 352 samples analysed. Antibiotic resistance profiles showed 114 (40%) isolates were resistant to ≥3 antimicrobial classes and were considered multidrug-resistant. Among multidrug-resistant (MDR) E. coli strains, 40 (14%) were resistant to 3 different antimicrobial classes, while 71 (25%) were resistant to between 4 and 7 antibiotic classes. Extended-spectrum β-lactamase resistance was found in 18 isolates: human (n = 14), cattle (n = 2), and environmental (n = 2). Both the blaCTX-M and blaTEM genes were detected in 10 and 15 strains, respectively. Sequence analysis showed that the isolates carried the blaTEM-116 (n = 7), blaTEM-1 (n = 5), and blaCTX-M-15 (n = 8) genes. Genotyping MDR isolates using (GTG) 5 PCR demonstrated that the isolates were not clonal. This data shows antimicrobial resistance profiles and different types of resistance genes in the E. coli population on dairy farms. As a result, more effective, targeted public health policies and measures need to be put in place to control and prevent the emergence and spread of resistant bacteria.

Insights on the structural characteristics of NDM-1: The journey so far

New Delhi metallo-β-lactamase (NDM-1) has created a medical storm ever since it was first reported;as it is active on virtually all clinically used β-lactam antibiotics. NDM-1 rampancy worldwide is now considered a nightmare scenario, particularly due to its rapid dissemination. An underlying theme in the majority of recent studies is structural characterization as knowledge of the three-dimensional structure of NDM-1 shall help find connections between its structure and function. Moreover, structural details are even critical in order to reveal the resistance mecha- nism to β-lactam antibiotics. In this perspective, we review structural characteristics of NDM-1 that have been delineated since its first report. We anticipate that these structure-function connections made by its characterization shall further serve as future guidelines for elucidating pathways towards de novo design of functional inhibitors.

Molecular Detection and Association of <i>QnrA</i>, <i>QnrB</i>, <i>QnrS</i>and <i>BlaCMY</i>Resistance Genes among Clinical Isolates of <i>Salmonella</i>spp. in Iran

Prevalence of three plasmid-mediated quinolone resistance determinant qnrA, qnrB, qnrS and extended spectrum Cephalosporins determinant blaCMY, among eighty-five isolates of Salmonella spp. collected in the community between 2008 and 2010 was determined by PCR. Not only qnr genes but also bla genes were positive in twenty-four different isolates. PCR assay detected that 22 of 85 (25.8%) Salmonella spp. carried the qnrA, 1 (1.17%) of 85 isolates harbored the qnrB, 1 (1.17%) of them contained the qnrS, 1 (1.17%) isolate carried all the three qnrA, qnrB, qnrS genes, 24 of 85 (28.2%) Salmonella carried blaCMY and 5 (5.88%) isolates carried qnrA and blaCMY. Antimicrobial susceptibility patterns of isolates were as follows: 49 (57.6%) exhibited resistance to Nalidixic acid and none of them to Ciprofloxacin. 33 (38.82%) isolates exhibited resistance to Cephalosporins and 2 (2.35%) of them exhibited ESBL phenotype and 12 (14.1%) isolates resistance to Ampicilin. These results were confirmed by MIC determination test as well. Having detected qnr and bla genes suggested that these genes spread antibiotic resistance among pathogenic bacteria.

Antimicrobial Profiles of Selected Gram-Negative Bacteria Recoverable from Sewage and Sludge from Juja and Kibera Informal Settlements of the Larger Nairobi Metropolis

Africa has experienced rapid urban migration in the past two decades. New informal settlements continue to emerge and expand but the sanitation provision of facilities has not improved at the same pace and this poses a serious health concern to the public especially the urban poor. Open sewage systems and sludge-clogged drainage systems as well as soil contaminated with industrial and domestic wastes are possible sources of germs that probably cause clinical infections and epidemics. In this cross-sectional study, we recorded diverse genera of Gram-negative non-fastidious bacteria that included;Escherichia coli (23%), Klebsiella spp (21%), Enterobacter spp (19%), Citrobacter spp (10%), Pseudomonas aeruginosa (8%), Proteus spp (7%), Salmonella (3%), Yersinia spp (3%), Shigella spp (2%), Morganella morganii (2%), Edwardisella spp (1%), Hafnia spp (1%), Serratia marcesence (0.5%), and Acinetobacter baumannii (0.5%). Most of these isolates were resistant to ampicillin while imipenem and ciprofloxacin were the most effective antimicrobial agents. Resistance combination towards ampicillin, trimethoprim, sulfamethoxazole and streptomycin was also noted in recovered isolates (16%). An overall high antimicrobial resistance was recorded among isolates from slum as compared to those recovered from Juja, a middle-class settlement located at the edge of Nairobi metropolis. The prevalence of isolates with a combined resistance to 3rd generation cephalosporins (cefotaxime, ceftriaxone and ceftazidime), gentamicin and ciprofloxacin was the highest among P. aeruginosa isolates (13%) but none of the Yersinia species and Edwardisella tarda exhibited this resistance. Carriage of blaTEM (52%) was most prevalent in all bacteria species followed by blaCTX-M (20%), blaSHV (18%) while blaOXA (17%) was the least common. The phylogeny analysis revealed significant genetic similarity among strains belonging to E. coli, K. pneumoniae, E. agglomerans and P. mirabilis strains but less relatedness was noted among strains belonging to C. freundii. Further analysis showed possible clonal expansion of E. agglomerans and K. pneumoniae within the environmental ecosystems.

Phenotypic and Genotypic Characterisation of Antibiotic Resistance in Escherichia coli, Klebsiella spp., and Listeria monocytogenes Isolates from Raw Meat Sold in Nairobi

Worldwide, the increase in antimicrobial resistance (AMR) is a public health concern. Food-borne associated antibiotic-resistant pathogens can contaminate raw meat during slaughter, transportation, and at sale points. A cross-sectional study was conducted from March 2021 to December 2021 to determine antimicrobial susceptibility patterns and characterize the molecular basis of resistance in E. coli, Klebsiella spp., and L. monocytogenes contaminating raw meat collected from retail outlets in Nairobi. Isolation and identification of the strains were done using the standard culture methods and PCR. Antimicrobial susceptibilities of the recovered strains were determined using disk diffusion while the presence of antibiotic resistance gene determinants;blaTEM, blaCTX-M, blaOXA, sul, and qnrS was done using PCR. Of 270 samples collected, 163 (60%) Escherichia coli, 19 (7%) Klebsiella spp., and L. monocytogenes 3 (1.1%) were recovered. Among Escherichia coli, high antibiotic resistance was found to Erythromycin 161 (98%) and ampicillin 88 (54%) while low resistance was found against imipenem 2 (1%). Similarly, high resistance was found among Klebsiella spp. to Erythromycin 19 (100%) and ampicillin 12 (63%) low resistance to ceftazidime 1 (5%), cefotaxime 1 (5%), aztreonam 1 (5%), and chloramphenicol 1 (5%). One isolate among the three Listeria monocytogenes strains isolated was resistant to Trimethoprim-sulfamethoxazole. No resistance was exhibited to gentamycin by all Klebsiella spp. The prevalence of multidrug-resistant (resistance to three or more classes of antibiotics) isolates was 95/182 (52.2%). The common resistance pattern observed was Erythromycin, ampicillin, tetracycline, and trimethoprim-sulfamethoxazole with a prevalence of 19 (20%). ESBL was confirmed in isolates that harbored: blaTEM (65%), blaCTX-M (44%), blaOXA (33%) while sul and qnrS were detected in 46.7% and 13.6% respectively. Circulation of antibiotic-resistant and MDR isolates found in this study could play a role in the dissemination of AMR among food-borne bacteria and suggest potential food safety and public health risk. Therefore, enhanced surveillance for antibiotic-resistant organisms in raw meat for early detection of emerging resistant bacteria species in the food chain is recommended.

Behavior of Antibiotic-Resistant Fecal Coliforms in the Stream of a Sewage Treatment Plant in Tokyo

We are confronting a new threat in the prevalence of antibiotic-resistant bacteria followed by epidemic spread in aquatic environments in metropolitan areas because damage from river floods is increasing remarkably in Japan due to global extreme weather. The sewer penetration rate is about 100% in Tokyo and reclaimed water from sewage treatment plants accounts for over 50% of all water in both the down- and mid-stream areas of local rivers. The water quality of these rivers, which contain microflora, seems to be seriously affected by reclaimed water. In this study, we collected water samples on July 17, 2018 and examined the behavior of antibiotic-resistant fecal coliforms in the stream of a sewage treatment plant in Tokyo. Extended-spectrum β-lactamase (ESBL)-producing fecal coliforms with encoding genes were found;the CTX-M-1, CTX-M-9, TEM, and SHV groups were found to have survived in the final effluent to the river after sterilization with sodium hypochlorite.

Characterization of Multidrug Resistant Escherichia coli Isolates Recovered from Humans and Chickens, Trinidad and Tobago

To characterize extended-spectrum beta-lactamase (ESBL) and extra-intestinal pathogenic Escherichia coli (ExPEC) associated virulence genes in E. coli isolates from chickens and humans in Trinidad and Tobago. This cross sectional study was conducted over a three-month period. A total of 471 E. coli isolates;160 from humans treated at a regional tertiary hospital and 311 from chicken caecal samples from “pluck shops” in Trinidad & Tobago were identified using both conventional and molecular microbiological methods. Phenotypic confirmation of ESBL producing E. coli isolates from humans was by Microscan system (Siemens, USA) while the double disk diffusion method was used for the chicken isolates. Polymerase chain reaction (PCR) analysis was used to determine the ESBL and ExPEC-associated virulence genes in representative human isolates and all chicken isolates. From the 311 chicken E. coli isolates, 49.2% (153/311) produced ESBL, while 56.3% (90/160) from humans were ESBL positive. All human and chicken ESBL isolates were 100% susceptible to carbapenems and aminoglycosides antimicrobials. PCR detected 21.1% blaCTX-M, 13.3% blaTEM and 7.8% blaSHV genes among E coli isolates from humans compared to 0.6% blaCTX-M and 48.6% blaTEM genes in chickens. PCR analysis revealed diverse virulence profiles among the isolates. There was a high occurrence rate of ExPEC-asso- ciated virulence genes in E. coli isolates from both humans and chickens. However, the CTX-M-1 genes were most predominant in humans while TEM occurred in chic- ken isolates. The diverse ESBL and virulence associated gene profiles encountered in E. coli isolates from humans and chickens on the surface depicts no similarity or relationships despite occurrence in both cohort groups. Therefore E. coli strains from chickens and humans require further investigation to determine their clonal relatedness or transmission in the country.

Genomic insights into the ESBL and MCR-l-producing ST648 Escherichia coli with multi-drug resistance

Polymyxin acts as an ultimate line of refuge against the severe infections by multidrug-resistant Gram- negative pathogens. This conventional idea is challenged dramatically by the recent discovery of mobile colistin resistance gene （mcr-1） is prevalent in food animals and human beings worldwide. More importantly, the mcr-1 gene was found to be co-localized with other antibiotic resistance genes, raising the possibility that super-bugs with pan-drug resistance are emerging. However, little is reported on the genomes of the mcr-l-positive bacterial host reservoirs. Here we report genome sequencing of three human isolates of the mcr-l-positive Escherichia coli （E15004, E15015 and E15017） and define general features through analyses of bacterial comparative genomics. Fur- ther genomic mining together with sequence typing allowed us to elucidate that the MCR-l-carrying E. coli E15017 belongs to the sequence type ST648 and copro- duces extended-spectrum β-1actamase （ESBL）. Given the fact that ST648 has been known to associate New Delhi metallo-β-1actamase 1 or ESBL, with either our results highlighted the possibility of ST648 as an epidemic clone with multidrug resistances.

A novel LEN-derived β-lactamase from Klebsiela pneumoniae

β-lactam antibacterial agents are the most commonly used antibiotics in clinic. The production of β-lactamases is the important mechanism for resistance to β-lactam antibiotics in Gram-negative bacteria. As a result of the generous use of β-lactam antibiotics, mutations of β-lactamases gene in bacteria are frequently developed to oppose against attack from antibiotics, novel β-lactamases were found one after another, among them SHV-28, CTX-M-11 and CTX-M-22 β-lactamases were first found by Chinese researchers.

CTX-M-14, CTX-M-24 and resistance in Escherichia coli and Klebsiella pneumoniae clinical isolates

Extended-spectrum β-lactamases （ESBLs） are the main cause of resistance to the third and forth-generation cephalosporins in Enterobacteriaceae, which are mediated by plasmids and can hydrolyze oxyiminoaminothiazolyl cephalosporins and monobactams. Most of ESBLs are mutants of the classical TEM and SHV types, with one or more amino-acid substitution（s） in the active site.

Antimicrobial susceptibility of Gram-negative bacteria causing intra-abdominal infections in China： SMART China 2011

Background The Study for Monitoring Antimicrobial Resistance Trends program monitors the activity of antibiotics against aerobic and facultative Gram-negative bacilli （GNBs） from intra-abdominal infections （IAIs） in patients worldwide.Methods In 2011,1 929 aerobic and facultative GNBs from 21 hospitals in 16 cities in China were collected.All isolates were tested using a panel of 12 antimicrobial agents,and susceptibility was determined following the Clinical Laboratory Standards Institute guidelines.Results Among the Gram-negative pathogens causing IAIs,Escherichia coli （47.3％） was the most commonly isolated,followed by Klebsiella pneumoniae （17.2％）,Pseudomonas aeruginosa （10.1％）,and Acinetobacter baumannii （8.3％）.Enterobacteriaceae comprised 78.8％ （1521/1929） of the total isolates.Among the antimicrobial agents tested,ertapenem and imipenem were the most active agents against Enterobacteriaceae,with susceptibility rates of 95.1％ and 94.4％,followed by amikacin （93.9％） and piperacillin/tazobactam （87.7％）.Susceptibility rates of ceftriaxone,cefotaxime,ceftazidime,and cefepime against Enterobacteriaceae were 38.3％,38.3％,61.1％,and 50.8％,respectively.The leastactive agent against Enterobacteriaceae was ampicillin/sulbactam （25.9％）.The extended-spectrum β-lactamase （ESBL） rates among E.coli,K.pneumoniae,Klebsiella oxytoca,and Proteus mirabilis were 68.8％,38.1％,41.2％,and 57.7％,respectively.Conclusions Enterobacteriaceae were the major pathogens causing IAIs,and the most active agents against the study isolates （including those producing ESBLs） were ertapenem,imipenem,and amikacin.Including the carbapenems,most agents exhibited reduced susceptibility against ESBL-positive and multidrug-resistant isolates.