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In vitro Activity of Ampicillin Against β-Lactamase Producing Enterobacterial Species
A.O. Shakak,H.A. Saeed
Current Research in Bacteriology , 2010,
Abstract: This study was undertaken to determine the in vitro activity of ampicillin against β-lactamase producing enterobacterial species. The study was conducted during the period December 2006-August 2009. Two hundred patients were investigated. Clinical specimens collected were 38.5% ear swabs, 36.5% wound swabs and 25% urine specimens. Cultivation of these specimens on enriched and/or differential media yielded 189 bacterial isolates, of which 96 were enterobacterial species. Among the enterobacterial isolates 62.5% were β-lactamase producers as indicated by β-lactamase acidometric method. Ampicillin activity against β-lactamase producers was determined by modified Kirby-Bauer Disc Diffusion technique. The technique was judged and approved by the National Committee for Clinical Laboratory Standards (NCCLS). The results showed that positive β-Lactamase isolates were E. coli 21.6%, K. pneumoniae 15.5%, P. mirabilis 13.7% and P. vulgaris 0.9%. The result indicated that only 8.6% of the β-lactamase producers were sensitive to ampicillin while 91.4% were resistant. It has been concluded that further studies are needed to validate the usefulness of ampicillin in treatment of enterobacterial infections in Sudanese patients.
Occurrence of Extended Spectrum Beta Lactamase Producings Resistant Escherichia coli and Klebsiella pneumoniae in Clinical Isolates and Associated Risk Factors
I.R. Iroha,G.O. Ezeifeka,E.S. Amadi,C.R. Umezurike
Research Journal of Biological Sciences , 2012,
Abstract: A total of 420 clinical isolates of Escherichia coli (235) and Klebsiella pneumoniae (185) were collected from 2 tertiary hospitals in Enugu to determine the presence of extended spectrum -lactamase enzymes and its associated risk factors. These isolates were obtained from different sources namely, urinary tract catheters (106), intensive care unit (bacteremia) (52), umbilical catheter (41), abdominal surgery site (91), antibiotic exposure (wound) (57) and arterial catheter (73). They were characterized using standard microbiological techniques. Production of ESBL was determined using the Double Disc Synergy Test (DDST) method and susceptibility of ESBL positive isolates to Gram negative antibiotic discs was carried out using disc diffusion technique. The result of this study showed that out of 420 clinical isolates of bacteria tested for ESBL enzyme production, 105 (44.6%) isolates of Escherichia coli comprising of 62 (41.3%) from University of Nigeria Teaching Hospital Enugu (UNTH) and 43 (57.8%) from Enugu State University teaching hospital Enugu (ESUTH) expresses ESBL enzymes. Also, 62 (33.5%) clinical isolates of K. pneumoniae comprising of 24 (20%) from UNTH and 38 (61.2%) from ESUTH yielded ESBL enzymes. The highest occurrence of ESBL enzyme were from umbilical catheter 39 (36.7%) where, 28 (26.4%) were from E. coli and 11 (10.3%) from K. pneumoniae, while the least were from the antibiotic exposure patients (bacteremia) 20 (35.0%), where 15 (26.3%) were from E. coli and 5 (8.7%) from K. pneumoniae. The susceptibility pattern of ESBL positive strains showed that they were multi-drug resistant except in ESUTH were these organisms were sensitive to ceftriaxone and ofloxacin (57.1%). The study suggests, the routine check for clinical isolates of ESBL production with particular emphasis on patients attending the ICU and those in invasive treatment is recommended.
Beta-lactamase Escherichia coli and Staphylococcus aureus isolated from chickens in Nigeria  [PDF]
Sunday Akidarju Mamza,Godwin Onyemaechi Egwu,Gideon Dauda Mshelia
Veterinaria Italiana , 2010,
Abstract: The occurrence of beta-lactamase-producing Escherichia coli and Staphylococcus aureus in chickens was investigated. Specimens (n = 1 300) were collected from 400 chickens and were streaked on MacConkey agar plates. From each plate, presumptive growths of organisms were picked and streaked on eosin methylene blue and Baird-Parker agars, respectively. Typical colonies of E. coli and S. aureus with similar morphologies were identified by biochemical tests. Isolates were tested for beta-lactamase production and antimicrobial susceptibilities. Results indicated that 805 E. coli isolates from which 89 (11%) were beta-lactamase-positive and 660 S. aureus from which 58 (8.8%) were beta-lactamase-positive. Both isolates showed a high level of resistance to all twelve antibiotics screened. The increased prevalence of antibiotic resistance amongst bacterial organisms is undoubtedly correlated with the discovery and characterisation of multiple, transferrable resistance determinants, such as beta-lactamases, corresponding to their respective phenotypes. The implications of this for humans when handling and/or consuming chickens and chicken products contaminated with strains of such isolates, is a risk of transferrable multi-drug resistance and a failure of treatment. The results of our study indicated that beta-lactamase-producing E. coli and S. aureus are prevalent in chickens in Nigeria.
Enzymatic analysis of the effect of naturally occurring Leu138Pro mutation identified in SHV β-lactamase on hydrolysis of penicillin and ampicillin
Nabin Rayamajhi, Jeong Joo, Seung Cha, Subarna Pokherl, Min Shin, Young Yoo, Han Yoo
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-29
Abstract: Kinetic analysis of the mutant proteins showed that Km value of the purified L138P mutant was comparatively higher than SHV-1, SHV-33 and SHV-33(L138P) enzyme for penicillin and ampicillin. Docking simulation of the SHV-1 and SHV-(L138P) enzymes also confirmed that β-lactamases preferred penicillin to ampicillin and the SHV-1 had a higher binding affinity for antibiotics compared to the SHV-(L138P) and other mutants.Our result demonstrated that L138P has a reduced role in penicillin and ampicillin hydrolyzing properties of SHV β-lactamases. These naturally occurring mutations rendering reduced function of the existing protein could trigger the emergence or acquisition of more effective alternative mechanisms for β-lactam hydrolysis.Antimicrobial resistance based on hydrolysis of the antibiotic by β-lactamases is currently a worldwide problem. It is one of the single most prevalent mechanisms responsible for resistance to β-lactams in clinical isolates of the Enterobacteriaceae [1-3]. Among the four classes (A to D) of β-lactamases, plasmid mediated class A and C β-lactamases have been of high clinical concern in hospital as well as community acquired infections [1,4]. Promiscuous plasmids carrying β-lactamase encoding genes are described to spread drug resistance among different groups of microbes under local selection pressure imposed by the commonly used antibiotics [1,5,3]. One of the most common plasmid mediated β-lactamase enzymes is closely related to TEM and SHV penicillinase [6,3]. Recently CTX-M and AmpC type β-lactamase are being widely reported from Enterobacteriaceae that are associated with nosocomial and community acquired infections [1,7].Use of extended-spectrum β-lactam antibiotics has led to the occurrence of variants of these β-lactamases carrying amino acid substitutions that alter the enzyme's substrate specificity [1,6,8,9]. SHV-1 is an important plasmid mediated β-lactamase found in the chromosome of most strains of Klebsiella pneumonia. Its h
Prevalence of extended-spectrum beta lactamase positive and multidrug resistance pattern of Escherichia coli and Klebsiella pneumoniae isolates, Semnan, Iran
Ali Jazayeri Moghadas
Iranian Journal of Microbiology , 2009,
Abstract: Background and Objectives: β-lactamase production is the predominant mechanism for resistance to β-lactams in Enterobacteriaceae. The producing isolates are often multidrug resistant and are major hosts for extended spectrum β-lactamases. This study was designed to determine the prevalence of extended-spectrum β-lactamase producing isolates of Escherichia coli and Klebsiella pneumoniae and their antibiotic resistance patterns in Semnan, Iran."nMaterials and Methods: 275 Escherichia coli and 107 K. pneumoniae isolates from clinical specimens were investigated. Combined disk test was used as a screening test for ESBL production. Disk diffusion test was performed for antibiotic susceptibility testing."nResults: The greatest resistance was observed against ampicillin (96.3%) and the least resistance was against ceftazidime (16.5%). Using combined disks as phenotypic confirmatory test, ESBL were detected among 69 (18.1%) of all isolates. Frequency of ESBL production was 17.45% and 19.6% for E. coli and K. pneumoniae respectively."nConclusion: High levels of resistance and ESBL production found in the E. coli and K. pneumoniae in this study make the choice of empirical antibiotic regimens difficult. Antimicrobial susceptibility testing and ESBL production monitoring are recommended in patients
beta-lactamase production Haemophilus spp. and resistance to ampicillin in a general hospital in Porto Alegre city, RS, Brazil (2001-2005)
Ferreira, Jorge A. S.;Castro, Andréa Cauduro de;Rocha, Marion P.;Riboldi, Gustavo;d'Azevedo, Pedro Alves;
Brazilian Journal of Infectious Diseases , 2007, DOI: 10.1590/S1413-86702007000100013
Abstract: in a four-year period (july/2001-june/2005), 410 haemophilus spp. isolates were studied. those were isolated from sputum at hospital nossa senhora da concei??o (nsc) in porto alegre city (rs). b-lactamase enzyme was detected in 113 (27.6%) of isolates through chromogenic cephalosporin method. fifty-eight (51.3%) of them showed sensibility to ampicillin through disc-diffusion method using haemophilus test medium (htm) by nccls criteria. in 297 (72.4%) isolates b-lactamase was not detected by chromogenic cephalosporin method. five (1.7%) of them were resistant and 1 (0.3%) intermediate to ampicillin using disc-diffusion method. the authors emphasized the importance of haemophilus spp. resistance to ampicillin research in clinical laboratories routine and the use of more than one method for this analysis was proposed, due to different resistance mechanisms in haemophilus spp.
Incorporation of phosphatidylcholine into Escherichia coli membrane affects secretion of penicillin b-lactamase

Xueli Cai,Yang Li,Wenjing Xuan,Xinguo Wang,

微生物学报 , 2008,
Abstract: OBJECTIVE: To study the biological function of phosphatidylcholine in bacteria, the borrelial pcs gene was inserted into ptac85 plasmid. Then E. coli Top10 pcs+ was constructed via the transformation of the recombinant plasmid. Phosphatidylcholine (30%) in total phospholipids was achieved when the bacterial cells were incubated in Luria-Bertani (LB) medium supplemented with 1% choline and induced by 0.5 mmol/L isopropy-beta-D-thiogalactoside (IPTG) for 4-8 hours at 37 degrees C. METHODS: Ampicillin inhibitionof E. coli Top10 pcs+ was tested at first, and then beta-lactamase activity in periplasm was examined. Finally Western blot was used to detect the amount of beta-lactamase in both bacterial periplasm and cytoplasm. RESULTS: Antibiotic tests showed that high concentrations of ampicillin inhibited the growth of E. coli Top100 pcs+ with an IC50 of 70-800 microg/mL. Active assays revealed that the beta-lactamase activity in periplasm was only 1/5 of that for the control strain E. coli Top10/p(tac)85. Western blotting confirmed that the low activity of beta-lactamase in E. coli Top10 pcs+ resulted from a lower amount of beta-lactamase in its periplasm. CONCLUSION: Our results demonstrated that the phospatidylcholine incorporated into bacterial membrane retarded secretion of Escherichia coli penicillin beta-lactamase from cytoplasm into periplasm, which suggested that phosphatidylcholine might play a role in the regulation of protein secretion in those bacteria able to synthesize phosphatidylcholine.
Extended Spectrum Beta – Lactamase (ESBL) Mediated Resistance to Antibiotics Among Klebsiella Pneumoniae in Enugu Metropolis
Iroha Ifeanyichukwu Romanus,Oji Anthonia Egwu,Afiukwa Tifani Ngozi,Nwuzo Agabus Chidiebube
Macedonian Journal of Medical Sciences , 2009,
Abstract: Aim. The objectives of this study were to determine the prevalence and antibiotic susceptibility patterns of extended – spectrum b - Lactamase (ESBL) producing Klebsiella pneumoniae isolated from three major diagnostic laboratories in Enugu State metropolis, Nigeria. Material and Methods. Clinical isolates of Klebsiella pneumoniae were obtained from urine, sputum and blood samples of patients attended diagnostic laboratories in Enugu metropolis. The isolates were subjected to susceptibility testing using Kirby and Bauer method of determining antimicrobial susceptibility and ESBL production was phenotypically determined using double disc synergy test.Results. A total of 300 clinical isolates of Klebsiella pneumoniae were isolated from three major diagnostic laboratories in Enugu namely Ambulin (100 urine samples), Mendex (100 blood sample) and Edisson (100 sputum samples) within a four month period (January – April 2009). ESBL production was determined among 300 isolates of Klebsiella pneumoniae and 186 (62%) Klebsiella pneumoniae express ESBL. ESBL producing Klebsiella pneumoniae were most frequently isolated from blood 76 (40.0%) followed by urine 66 (30.5%) and sputum 44 (23.6%). Resistance patterns of Klebsiella pneumoniae revealed that 64% were resistance to sparfloxacin, 92.6% to gentamicin, 90.9% to fusidic acid, 82.3% to erythromycin, 79% to trimethoprim, 96.3% to sulphamethoxazole, 88.5% to tetracycline 31.2% to nitrofurantoin, 31.2% to ciprofloxacin, 69% to ceftazidime, 74% to cefotaxime, 79.6% to ceftriaxone and 0% to imipenem.Conclusion. ESBL producing Klebsiella pneumoniae were present in these diagnostic laboratories and were resistant to different classes of antibiotics resulting in limited treatment options. Therefore we suggest that it will be important to perform screening and confirmatory tests for ESBL detection to any organisms resistant to any of the second and third generation cephalosporins in a routine diagnostic laboratory work.
Glucuronidase activity of Escherichia coli isolated from chicken carcasses
Perin, Luana Martins;Yamazi, Anderson Keizo;Moraes, Paula Mendon?a;Cossi, Marcus Vinícius Coutinho;Pinto, Paulo Sérgio de Arruda;Nero, Luís Augusto;
Brazilian Journal of Microbiology , 2010, DOI: 10.1590/S1517-83822010000300036
Abstract: to identify escherichia coli through the production of β-d-glucuronidase (gud), 622 suspect cultures were isolated from chicken carcasses and plated in petrifilmtm ec. of these cultures, only 44 (7.1%) failed to produce gud. this result indicates the usefulness of gud production for estimating e. coli populations in chicken.
Phenotypic detection of extended spectrum ?-lactamase and AmpC ?-lactamase in urinary isolates of Escherichia coli at a tertiary care referral hospital in Northeast India  [PDF]
A Bora,GU Ahmed,NK Hazarika
Journal of College of Medical Sciences-Nepal , 2012, DOI: 10.3126/jcmsn.v8i3.8682
Abstract: Objective Urinary tract infections (UTIs) are the most prevalent infections worldwide, mostly caused by Escherichia coli . Emerging antibiotic resistance due to extended spectrum a-lactamase (ESBL) and AmpC β- lactamase production limit the use of β-lactam antibiotics against the infections caused by E. coli. We detected the production of ESBL and AmpC β-lactamase in urinary isolates of E. coli, recovered from a tertiary care referral hospital in Northeast India. Materials and Methods A total of 140 E. coli urinary isolates were recovered during October 2008 to January 2009. Antibiotic susceptibility testing and ESBL detection were carried out according to Clinical Laboratory and Standards Institute (CLSI) guidelines. Phenotypic detection of AmpC β-lactamase was carried out by AmpC disc method. Results Among the 140 urinary isolates, 112 isolates (80%) were multi-drug resistance (MDR). ESBL was detected in 67.14% (94/140) of E. coli isolates. AmpC β-lactamase was detected in 22.34% of ESBL producing E. coli isolates. Conclusions Routine testing for ESBL and AmpC β-lactamase in E. coli urinary isolates with conventional antibiogram would be useful for strict antibiotic policy implementation in hospitals, to estimate the impact of increased drug resistance and to take steps for reducing their resistance. Journal of College of Medical Sciences-Nepal, 2012, Vol-8, No-3, 22-29 DOI: http://dx.doi.org/10.3126/jcmsn.v8i3.8682
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