scholarly journals Beta-lactamases and detection of beta-lactam resistance in Enterobacter spp.

1997 ◽  
Vol 41 (1) ◽  
pp. 35-39 ◽  
Author(s):  
J D Pitout ◽  
E S Moland ◽  
C C Sanders ◽  
K S Thomson ◽  
S R Fitzsimmons
Keyword(s):  
Disk Diffusion ◽  
Broth Microdilution ◽  
Beta Lactam ◽  
Disk Diffusion Test ◽  
Beta Lactamases ◽  
Beta Lactam Antibiotics ◽  
Resistant Strains ◽  
Group 2 ◽  
Susceptibility Tests ◽  
Group 1

Enterobacter spp. are becoming increasingly frequent nosocomial pathogens, and beta-lactam-resistant strains are on the increase, especially among isolates recovered from intensive care units. Therefore, a study was designed to characterize the beta-lactamases produced by 80 isolates of E. cloacae, E. aerogenes, E. taylorae, E. gergoviae, E. sakazakii, E. asburiae, and E. agglomerans by induction studies, spectrophotometric hydrolysis assays, and isoelectric focusing. The ability of broth microdilution and disk diffusion susceptibility tests to detect resistance to 16 beta-lactam antibiotics among these species was also assessed. All species except E. agglomerans, E. gergoviae, and some isolates of E. sakazakii were found to produce a Bush group 1 cephalosporinase that was expressed inducibly or constitutively at high levels. In addition, some strains also produced a Bush group 2 beta-lactamase. In comparisons of broth microdilution and disk diffusion tests, disk diffusion tests failed to detect resistance in 1 of 25 isolates resistant to aztreonam and 2 of 30 isolates resistant to ceftazidime. These results indicate that species of Enterobacter can possess a variety of beta-lactamases that are responsible for beta-lactam resistance in this genus and that the disk diffusion test may occasionally miss resistance in some strains.

scholarly journals Cross-Reactivity of Drug-Dependent Antibodies in Patients with Immune Thrombocytopenia Induced By Beta-Lactam Antibiotics

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2350-2350
Author(s):  
Matthew John Slaught ◽  
Daniel W. Bougie ◽  
Richard H. Aster
Keyword(s):  
Bacterial Infections ◽  
Immune Thrombocytopenia ◽  
Conflicts Of Interest ◽  
Cross Reactivity ◽  
Beta Lactam ◽  
Cross Reactions ◽  
Beta Lactam Antibiotics ◽  
Wide Range ◽  
Group 2 ◽  
Group 1

More than 50 beta lactam (BL) antibiotics are now in active use for treatment of a wide range of bacterial infections. BL antibiotics are among the most common drugs capable of inducing antibodies (DDAbs) that cause drug-induced immune thrombocytopenia (DITP). Most DDAbs are highly specific for the sensitizing drug but beta lactams all have a common core structure and many similarities among side groups that are added to augment potency and modify specificity, raising the possibility that a DDAb specific for one BL may cross-react with another. We studied DDAbs from 33 patients with DITP induced by 9 commonly used BL drugs to determine whether patterns of cross-reactivity exist that might influence the choice of an alternative antibiotic in a patient with BL-induced DITP. DDAbs were demonstrated in a flow cytometric assay considered to be "positive" when immunoglobulins in patient serum but not normal serum react with normal platelets in the presence, but not in the absence of drug (Blood 2018;131:1486). DDAbs detected in the 33 patients were specific for 9 different BL drugs that were divided into two groups, "penicillins" (Group 1) and cephalosporins (Group 2) on the basis of structural similarities (Figure 1). In Group 1 were 19 DDAbs specific for amoxicillin (2), nafcillin (4) and piperacillin (13). Structurally similar ampicillin and penicillin were also tested with these abs. In Group 2 were 14 DDAbs specific for cefadroxil (1), cefepime (2), ceftazidime (2), ceftizoxime (1), ceftriaxone (7) and cephalexin 1). Cross-reactions identified within these groups of DDAbs are shown in Tables 1 and 2. Cross-reactions, many quite strong (S) were observed among DDAbs specific for drugs in both structural groups (Tables 1 and 2). Particularly noteworthy were cross-reactions of the 19 Group 1 DDAbs with ampicillin (6) and penicillin (6) (Table 1) and of the 14 Group 2 DDAbs with cefepime (6), ceftizoxazole (6) and ceftriaxone (3) (Table 2). The findings show that platelet-specific DDAbs induced by beta lactam antibiotics, in contrast with those induced by medications like quinine, sulfamethoxazole and vancomycin, commonly cross-react with other antibiotics of this class. In patients with immune thrombocytopenia induced by a beta lactam antibiotic, it may be prudent to avoid switching to another beta lactam or, if this is necessary, to monitor platelet counts carefully. Disclosures No relevant conflicts of interest to declare.

scholarly journals Evaluation of the presence of AmpC (FOX) beta-lactamase gene in clinical strains of Escherichia coli isolated from hospitalized patients in Tabriz, Iran

2021 ◽  
Vol 38 (3) ◽  
pp. 301-304
Author(s):  
Zahra SADEGHI DEYLAMDEH ◽  
Abolfazl JAFARI SALES
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Hospitalized Patients ◽  
Disk Diffusion ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
Clinical Strains ◽  
Beta Lactam Antibiotics ◽  
Lactamase Gene

Beta-lactamases are the most common cause of bacterial resistance to beta-lactam antibiotics. AmpC-type beta-lactamases hydrolyze cephalosporins, penicillins, and cephamycins. Therefore, the study aims was to determine antibiotic resistance and to investigate the presence of AmpC beta-lactamase gene in clinical strains of Escherichia coli isolated from hospitalized patients in Tabriz. In this cross-sectional descriptive study, 289 E. coli specimens were collected from clinical specimens. Disk diffusion method and combined disk method were used to determine the phenotype of extended spectrum β-Lactamase producing (ESBLs) strains. Then PCR was used to evaluate the presence of AmpC (FOX) beta-lactamase gene in the strains confirmed in phenotypic tests. Antibiotic resistance was also determined using disk diffusion by the Kibry-Bauer method. A total of 121 isolates were identified as generators of beta-lactamase genes. 72 (59.5 %) isolates producing ESBL and 49 (40.5 %) isolates were identified as AmpC generators. In the PCR test, 31 isolates contained the FOX gene. The highest resistance was related to the antibiotics amoxicillin (76.12%), ceftazidime (70.24%) and nalidixic acid (65.05%). The results indicate an increase in the prevalence of beta-lactamase genes and increased resistance to beta-lactam antibiotics, which can be the result of improper use of antibiotics and not using antibiotic susceptibility tests before starting treatment. Also, using phenotypic and molecular diagnostic methods such as PCR together can be very useful.

scholarly journals Conjugative Plasmids Disseminating CTX-M-15 among Human, Animals and the Environment in Mwanza Tanzania: A Need to Intensify One Health Approach

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 836
Author(s):  
Caroline A. Minja ◽  
Gabriel Shirima ◽  
Stephen E. Mshana
Keyword(s):  
One Health ◽  
Animal Origin ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
Extended Spectrum Beta Lactamase ◽  
Beta Lactam Antibiotics ◽  
Extended Spectrum ◽  
Plasmid Replicon ◽  
Susceptibility Tests

Background: Globally, blaCTX-M-15 beta-lactamases are the most popular extended spectrum beta-lactamase alleles that are widely distributed due its mobilisation by mobile genetic elements in several compartments. We aimed to determine the conjugation frequencies and replicon types associated with plasmids carrying blaCTX-M-15 gene from Extended Spectrum Beta-lactamase producing isolates in order to understand the dissemination of resistance genes in different compartments. Material and methods: A total of 51 archived isolates carrying blaCTX-M-15 beta-lactamases were used as donors in this study. Antibiotic susceptibility tests were performed as previously described for both donors and transconjugants. Conjugation experiment was performed by a modified protocol of the plate mating experiment, and plasmid replicon types were screened among donor and transconjugant isolates by multiplex Polymerase Chain Reaction in a set of three primer panels. Results: The conjugation efficiency of plasmids carrying blaCTX-M-15 was 88.2% (45/51) with conjugation frequencies in the order of 10−1 to 10−9 and a 100% transfer efficiency observed among E. coli of animal origin. Majority of donors (n = 21) and transconjugants (n = 14) plasmids were typed as either Inc FIA or Inc FIB. Resistance to non-beta-lactam antibiotics was transferrable in 34/45 (75.6%) of events. Ciprofloxacin, tetracycline and sulphamethoxazole-trimethoprim resistance was co-transferred in 29/34 (85.3%) such events. Gentamicin resistance was transferred in 17/34 (50%) of events. Conclusions: Majority of plasmids carrying blaCTX-M-15 were conjugatively transferred by IncF plasmids along with non-beta lactam resistance. There is a need for more research on plasmids to understand how plasmids especially multi replicon plasmids interact and the effect of such interaction on conjugation. One Health approach is to be intensified to address antimicrobial resistance which is a public health threat.

Performance Accuracy of Antibacterial and Antifungal Susceptibility Test Methods: Report From the College of American Pathologists Microbiology Surveys Program (2001–2003)

2006 ◽  
Vol 130 (6) ◽  
pp. 767-778 ◽  
Author(s):  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
Antifungal Susceptibility ◽  
Test Methods ◽  
Disk Diffusion ◽  
Test Accuracy ◽  
Broth Microdilution ◽  
Coagulase Negative Staphylococci ◽  
Disk Diffusion Test ◽  
Gram Negative ◽  
Antibacterial Test ◽  
Susceptibility Tests

Abstract Context.—The College of American Pathologists Microbiology Surveys Program provides external proficiency samples that monitor the performance of nearly 3000 laboratories that perform and report antimicrobial susceptibility tests. Objective.—To summarize results obtained with bacterial and yeast challenge samples (2001 through 2003). Design.—One organism every 4 months was tested by surveys participants against antibacterials/antifungals by routinely used methods. Reports were graded by interpretive category (susceptible, intermediate, resistant) based on an 80% consensus of referees/participants. Results.—The most common antibacterial test methods/ systems were Vitek (38%–43%), MicroScan (39%–43%), and the disk diffusion test (14%–15%), although Etest was most used for fastidious species. YeastOne was the dominant antifungal test (50%–55%). Antifungal results demonstrated continuous, improved accuracy (83%–88%), highest for YeastOne (96%) and broth microdilution (95%) methods. Antibacterial test accuracy was consistently greater than 97% against gram-positive organism challenges and greater than 98% against gram-negative challenges. For gram-negative strains with well-characterized resistance mechanisms, the accuracy by method was disk diffusion greater than broth microdilution greater than automated systems. Major problems identified were (1) Haemophilus influenzae control ranges require re-evaluation, (2) overuse of β-lactamase tests, (3) errors among Enterococcus faecium against penicillins (Vitek 2, MicroScan), (4) false-susceptible results with trimethoprim/sulfamethoxazole against coagulase-negative staphylococci (MicroScan), (5) macrolide false-susceptibility for β-hemolytic streptococcus (MicroScan), (6) flawed reporting for antimicrobials not active at the infection site, (7) use of outdated interpretive criteria, and (8) failure to follow Clinical and Laboratory Standards Institute testing/reporting recommendations. Conclusions.—Susceptibility tests were generally performing satisfactorily as measured by the surveys, but serious errors were identified with some drug/organism combinations that may require action by the Clinical and Laboratory Standards Institute and/or the Food and Drug Administration.

scholarly journals Phenotypic detection of Carbapenamase among Klebsiella pneumoniae isolated from clinical samples using modified Hodged test

2020 ◽  
Vol 13 (3) ◽  
pp. 135-140
Author(s):  
HauwaYakubu ◽  
Mahmud Yerima Iliyasu ◽  
Asma’u Salisu ◽  
Abdulmumin Ibrahim Sulaiman ◽  
Fatima Tahir ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Susceptibility Testing ◽  
University Teaching ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
Beta Lactam Antibiotics ◽  
Microbiological Techniques ◽  
Tract Infections

Carbapenemases are microbial enzymes that confer resistance to virtually all available beta-lactam antibiotics and the most frequent carbapenemases are the Klebsiella pneumoniae Carbapenamase (KPC). Detection of carbapenemases is a significant infection control strategy as the enzymes are often associated with extensive antimicrobial resistance, therapeutic failures and mortality associated with infectious diseases. A total of 400 clinical samples were collected from different groups of patients in Abubakar Tafawa Balewa University Teaching Hospital, Bauchi, Nigeria and 118 K. pneumoniae were isolated using standard microbiological techniques. The isolates were subjected to antibiotic susceptibility testing by Kirby-Bauer disc diffusion method, then screened for Carbapenamase production using modified Hodge test. The results indicated that the isolates were resistant to Ampicillin (61.9%), Ceftriaxone (50.8%) and Ceftazidime (50.8%), then Ciprofloxacin (54.2%), but predominantly sensitive to Imipenem (66.9%), Eterpenem (60.2%) and Meropenem (65.3%). It was found that 38 (32.2%) of the isolates phenotypically shows the presence of Carbapenamase, with highest frequency of (40.7%) among patients, mainly adult females with cases of Urinary Tract Infections (UTIs) and the least from wound (11.8%).This study revealed that the isolates produced other beta-lactamases than KPC or variants of Carbapenamase that cannot be detected by modified Hodge test, thus shows low resistance to carbapenems. Therefore further studies is needed to genotypically confirm the presence of KPC in these isolates.

scholarly journals Species-Specific Sensitivity of Coagulase-Negative Staphylococci to Single Antibiotics and Their Combinations

2011 ◽  
Vol 60 (2) ◽  
pp. 155-161 ◽  
Author(s):  
GRAŻYNA SZYMAŃSKA ◽  
MAGDALENA SZEMRAJ ◽  
ELIGIA M. SZEWCZYK
Keyword(s):  
University Hospital ◽  
Hospital Environment ◽  
Beta Lactam ◽  
Coagulase Negative Staphylococci ◽  
Methicillin Resistant ◽  
Beta Lactam Antibiotics ◽  
Resistant Strains ◽  
Staphylococcus Hominis ◽  
Species Specific

The activity of beta-lactam antibiotics (oxacillin, cloxacillin, cephalotin), vancomycin, gentamicin and rifampicin applied in vitro individually and in combination against 37 nosocomial methicillin-resistant strains of coagulase-negative staphylococci (CNS) was assessed to demonstrate the heterogeneity of this group of bacteria and estimate the chance of the efficacy of such therapy. The strains belonged to four species: Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus cohnii, Staphylococcus hominis. They originated from a hospital environment and from the skin of medical staff of the intensive care unit of a paediatric ward at a university hospital. All strains were methicillin-resistant, according to CLSI standards, but individual strains differed in MIC(ox) values. Susceptibility to other tested antibiotics was also characteristic for the species. The increased susceptibility to antibiotics in combinations, tested by calculating the fractional inhibitory concentration (FIC) index, concerned 26 out of 37 investigated strains and it was a feature of a particular species. Combinations of vancomycin and cephalotin against S. epidermidis and oxacillin with vancomycin were significant, as well as cephalotin and rifampicin in growth inhibition of multiresistant S. haemolyticus strains.

scholarly journals Variation in erythromycin and clindamycin susceptibilities of Streptococcus pneumoniae by four test methods.

1997 ◽  
Vol 41 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E L Fasola ◽  
S Bajaksouzian ◽  
P C Appelbaum ◽  
M R Jacobs
Keyword(s):  
Streptococcus Pneumoniae ◽  
Susceptibility Testing ◽  
Ambient Air ◽  
Test Methods ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Resistant Strains

Susceptibilities of 124 strains of Streptococcus pneumoniae to erythromycin and clindamycin were determined by the National Committee for the Clinical Laboratory Standards (NCCLS) broth microdilution method, with incubation for 20 to 24 h in ambient air and with modifications of this method by incubation for up to 48 h in air and CO2. Strains were also tested by agar dilution, E-test, and disk diffusion; good correlation was obtained with these methods, with clear separation into bimodal populations of susceptible and resistant stains. The broth microdilution method, however, using incubation in air for 24 h (NCCLS method), misclassified 4 of 92 erythromycin-resistant strains (1 as susceptible and 3 as intermediate) and 25 of 58 clindamycin-resistant strains (all as susceptible). With the exception of one strain with clindamycin, susceptible and resistant strains were correctly classified by the microdilution method with incubation in CO2 for 24 h or in ambient air for 48 h. Disk diffusion, agar dilution, and E-test methods with incubation in 5% CO2 are therefore reliable methods for susceptibility testing of pneumococci against these agents. However, the NCCLS microdilution method, which specifies incubation for 20 to 24 h in ambient air, produced significant very major errors (43%) clindamycin. Modification of the microdilution method by incubation in 5% CO2 or by extension of incubation time in ambient air to 48 h corrected these errors. Disk diffusion, however, was shown to be a simple, convenient, and reliable method for susceptibility testing of pneumococci to erythromycin and clindamycin and is suggested as the method of choice for these agents.

scholarly journals MIC and time-kill studies of antipneumococcal activity of GV 118819X (sanfetrinem) compared with those of other agents.

1997 ◽  
Vol 41 (1) ◽  
pp. 148-155 ◽  
Author(s):  
S K Spangler ◽  
M R Jacobs ◽  
P C Appelbaum
Keyword(s):  
United States ◽  
The United States ◽  
Broth Microdilution ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Amoxicillin Clavulanate ◽  
Agar Dilution ◽  
Resistant Strains ◽  
Time Kill

Agar dilution MIC methodology was used to test the activities of GV 118819X (sanfetrinem), ampicillin, amoxicillin, amoxicillin-clavulanate, cefpodoxime, loracarbef, levofloxacin, clarithromycin, ceftriaxone, imipenem, and vancomycin against 53 penicillin-susceptible, 84 penicillin-intermediate and 74 penicillin-resistant pneumococci isolated in the United States. GV 118819X was the most active oral beta-lactam, with MIC at which 50% of the isolates were inhibited (MIC50)/MIC90 values of 0.008/0.03, 0.06/0.5, and 0.5/1.0 micrograms/ml against penicillin-susceptible, -intermediate, and -resistant stains, respectively. Amoxicillin and amoxicillin in the presence of clavulanate (2:1) were the second most-active oral beta-lactams, followed by ampicillin and cefpodoxime; loracarbef was not active against penicillin-intermediate and -resistant strains. Clarithromycin was most active against penicillin-susceptible strains but was less active against intermediate and resistant stains. All pneumococcal stains were inhibited by ceftriaxone and imipenem at MICs of < or = 4.0 and < or = 1.0 micrograms/ml, respectively. The activities of levofloxacin and vancomycin were unaffected by penicillin susceptibility. Time-kill studies of three penicillin-susceptible, three penicillin-intermediate, and three penicillin-resistant pneumococci showed that all compounds, at the broth microdilution MIC, yielded 99.9% killing of all strains after 24 h. Kinetic patterns of all oral beta-lactams, ceftriaxone, and vancomycin were similar relative to the MIC, with 90% killing of all strains first observed after 12 h. However, killing by amoxicillin-clavulanate, imipenem, and levofloxacin was slightly faster and that by clarithromycin was slower than that by the above-described drugs. At 2 x the MIC, more strains were killed earlier than was the case at the MIC, but the pattern seen at the MIC prevailed. When MICs and kill kinetics were combined, sanfetrinem was the most active oral antipneumococcal agent in this study.

scholarly journals Ceftaroline resistance in Staphylococcus pseudintermedius gene mecA carriers

2018 ◽  
Vol 38 (12) ◽  
pp. 2233-2236
Author(s):  
Carolina B. Scherer ◽  
Larissa S. Botoni ◽  
Antônio U. Carvalho ◽  
Kelly M. Keller ◽  
Adriane P. Costa-Val
Keyword(s):  
Methicillin Resistance ◽  
Meca Gene ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Staphylococcus Pseudintermedius ◽  
Ceftaroline Fosamil ◽  
Disk Diffusion Test ◽  
Methicillin Resistant ◽  
Resistant Strains ◽  
Current Report

ABSTRACT: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) being a constant concern, ceftaroline fosamil has been recently approved as a new cephalosporin, active against MRSA, for use in humans; only rare cases of resistance have been reported till date. There is no report of resistance to ceftaroline in Staphylococcus pseudintermedius, which is the main bacterium causing dermatitis and otitis in dogs. To evaluate staphylococcal resistance to ceftaroline, 35 isolates of methicillin-resistant S. pseudintermedius (MRSP), carrying the mecA gene, from 26 dogs with folliculitis and nine dogs with external otitis, underwent disk diffusion test with cefoxitin, oxacillin, and ceftaroline. Tests with cefoxitin and oxacillin showed > 90% sensitivity in methicillin resistance detection. In the disk diffusion test, 97.14% (34/35) were resistant to cefoxitin, 94.29% (33/35) to oxacillin, and 31.43% (11/35) to ceftaroline. Of the ceftaroline-resistant strains, 27.27% (3/11) were obtained from the ears of dogs while the rest (8/11) were from the skin. The current report is the first description of MRSP resistance to ceftaroline.

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