Comparision of Three Laboratory Tests for Detection of AmpC β Lactamases in Klebsiella Species and E. Coli

Location, Location, Location: Establishing Design Principles for New Antibacterials from Ferric Siderophore Transport Systems

This review strives to assemble a set of molecular design principles that enables the delivery of antibiotic warheads to Gram-negative bacterial targets (ESKAPE pathogens) using iron-chelating siderophores, known as the Trojan Horse strategy for antibiotic development. Principles are derived along two main lines. First, archetypical siderophores and their conjugates are used as case studies for native iron transport. They enable the consideration of the correspondence of iron transport and antibacterial target location. The second line of study charts the rationale behind the clinical antibiotic cefiderocol. It illustrates the potential versatility for the design of new Trojan Horse-based antibiotics. Themes such as matching the warhead to a location where the siderophore delivers its cargo (i.e., periplasm vs. cytoplasm), whether or not a cleavable linker is required, and the relevance of cheaters to the effectiveness and selectivity of new conjugates will be explored. The effort to articulate rules has identified gaps in the current understanding of iron transport pathways and suggests directions for new investigations.

Beta-lactam Resistance Profile among Klebsiella pneumoniae Clinical Isolates from Alexandria, Egypt

Klebsiella pneumoniae is a major drug-resistant human pathogen accountable for a wide range of infections. In this cross-sectional study, we aimed to determine the phenotypic and genotypic features of β-lactamase-producing K. pneumoniae clinical isolates from Alexandria, Egypt. A total of 50 nonduplicated clinical isolates of K. pneumoniae were obtained from various specimens. They were identified biochemically and by biotyping using mass spectrometry. For molecular characterization, plasmid profile analysis was performed. Screening for extended spectrum β-lactamases (ESBLs), carbapenemases and AmpC production was carried out phenotypically and genotypically. Correlation analysis was performed to assess the relationship between phenotype, genotype and resistance patterns among the studied isolates. The dendrogram demonstrated 38 distinct plasmid profiles among 62% of our isolates. According to antimicrobial susceptibility testing, 90% of isolates were multi/extensive-drug resistant. Nineteen out of 50 (38%) were resistant to cefoxitin, while only 10 (20%) were resistant to imipenem. All isolates were susceptible to colistin. Phenotypically, ESBL producers (78%) were the most common, followed by carbapenemase producers (24%). Genotypically, the most common ESBL gene was blaSHV (90%), followed by blaCTX-Mu (74%), while the most common carbapenemase genes were blaNDM (56%) and blaOXA-48 (54%). No blaKPC or blaIMP were detected. Plasmid-mediated AmpC resistance was confirmed in only two out of 19 cefoxitin-resistant isolates. Both the blaNDM and blaOXA.48 genes were significantly positive correlated (rho = 0.56, p = 0.004). Absence of blaKPC among carbapenem resistant K. pneumoniae isolates in Alexandria, Egypt. AmpC production is not the main factor behind the resistance to cefoxitin among our isolates.

Metallo-β-lactamase and AmpC genes in Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa isolates from abattoir and poultry origin in Nigeria

Background

Gram-negative bacteria (GNB) including Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae represent the most relevant reservoir of resistance genes such as metallo-β-lactamase (MBL) and AmpC genes that give them the undue advantage to resist antimicrobial onslaught. This study aimed to investigate the occurrence of MBL (bla_IMP-1, bla_IMP-2, bla_VIM-1, bla_VIM-2) and AmpC (bla_FOX, bla_DHA, bla_CMY, bla_ACC) resistance genes in aforementioned GNB collected from abattoir and poultry sources in Nigeria.

Results

In total, 370 isolates were collected from abattoir tables (n = 130), anal region of cows (n = 120), and the cloacae of poultry birds (n = 120). The test isolates showed high rate of resistance to cephalosporins and carbapenems. The MBLs were phenotypically detected in 22 E. coli, 22 P. aeruginosa, and 18 K. pneumoniae isolates using combined disc test (CDT). However, only 11 E. coli, 24 P. aeruginosa, and 18 Klebsiella pneumoniae isolates were phenotypically confirmed to be AmpC producers using cefoxitin-cloxacillin double disk synergy test (CC-DDST). MBL encoding genes (particularly the bla_IMP-1 genes and bla_IMP-2 genes) were detected by polymerase chain reaction (PCR) in 12 (54.6%) E. coli, 15 (83.3%) K. pneumoniae, and 16 (72.7%) P. aeruginosa isolates. AmpC genes (particularly the bla_CMY genes and bla_FOX genes) were found in a total of 5 (29.4%) E. coli isolates, 5 (27.8%) isolates of K. pneumoniae, and 10 (41.7%) isolates of P. aeruginosa.

Conclusions

Our study showed the circulation of MBL and AmpC genes in GNB from abattoir and poultry origin in Nigeria. Adoption of regular control policies is necessary to reduce the spread of these species as soon as possible, especially in poultry and slaughterhouses.

Prevalence of plasmid-mediated AmpC beta-lactamases in Enterobacteria isolated from urban and rural folks in Uganda

Background: AmpC beta-lactamase-producing bacteria are associated with increased resistance to third-generation cephalosporins. Here, we describe plasmid-mediated AmpC beta-lactamase-producing enterobacteria isolated from urban and rural dwellers in Uganda. Methods: Stool and urine from 1,448 individuals attending outpatient clinics in Kampala and two rural districts in central Uganda were processed for isolation of Escherichia coli and Klebsiella. Following antibiotic susceptibility testing, cefoxitin resistant isolates, and amoxicillin/clavulanate resistant but cefoxitin susceptible isolates, were tested for AmpC beta-lactamase production using the cefoxitin-cloxacillin double-disc synergy test. Carriage of plasmid-mediated AmpC beta-lactamase-encoding genes (pAmpC) and extended spectrum beta-lactamase (ESBL) encoding genes was determined by PCR. Results: Nine hundred and thirty E. coli and 55 Klebsiella were recovered from the cultured samples, yielding 985 isolates investigated (one per participant). One hundred and twenty-nine isolates (13.1%, 129/985) were AmpC beta-lactamase producers, of which 111 were molecularly characterized for pAmpC and ESBL gene carriage. pAmpC genes were detected in 60% (67/111) of the AmpC beta-lactamase producers; pAmpC genes were also detected in 18 AmpC beta-lactamase non-producers and in 13 isolates with reduced susceptibility to third-generation cephalosporins, yielding a total of 98 isolates that carried pAmpC genes. Overall, the prevalence of pAmpC genes in cefoxitin resistant and/or amoxicillin/clavulanate resistant E. coli and Klebsiella was 59% (93/157) and 26.1% (5/23), respectively. The overall prevalence of pAmpC-positive enterobacteria was 10% (98/985); 16.4% (45/274) in Kampala, 6.2% (25/406) Kayunga, and 9.2% (28/305) Mpigi. Ciprofloxacin use was associated with carriage of pAmpC-positive bacteria while residing in a rural district was associated with protection from carriage of pAmpC-positive bacteria. Conclusion: pAmpC beta-lactamase producing enterobacteria are prevalent in urban and rural dwellers in Uganda; therefore, cefoxitn should be considered during routine susceptibility testing in this setting.

Geographical Distribution of β-Lactam Resistance among Klebsiella spp. from Selected Health Facilities in Ghana

β-Lactam-resistant Klebsiella isolates continue to cause multidrug resistance infections worldwide. This study aimed to describe the geographical distribution of extended spectrum β-lactamase (ESBL), AmpC β-lactamase (AmpC), and carbapenemase production among 139 Klebsiella isolates recovered from patients at major referral health facilities in Ghana. The phenotypic methods of combined disc diffusion test, modified three-dimensional test, modified Hodge test (MHT), and combined disc test were performed for each isolate to detect ESBL, AmpC, carbapenemase, and metallo-β-lactamase (MBL) producers, respectively. Except for MBL, all other β-lactam resistance mechanisms were highest in the healthcare facilities situated in the northern belt of Ghana. Significant regional difference of ESBL producers was observed between the northern and middle belts as well as the northern and southern belts. Genotypic detection with polymerase chain reaction (PCR) revealed the presence of bla TEM 36/139 (25.9%), bla SHV 40/139 (28.8%), bla CTX-M 37/139 (26.6%), bla OXA-48 3/139 (2.16%), and bla NDM 1/139 (0.72%) genotypes. In conclusion, there were variations in β-lactam resistance among Klebsiella spp. from health facilities situated in the northern, middle, and southern belts of Ghana. The study provides preliminary evidence that emphasizes the need to direct more attention to antimicrobial resistance control, especially in the northern belt of Ghana. Findings from this study may be critical for creating and fine-tuning effective antimicrobial resistance control strategies and for informing accurate antibiotic prescription by practitioners.

Phenotypic Characterization and Antibiotic Resistance Patterns of Extended-Spectrum β-Lactamase- and AmpC β-Lactamase-Producing Gram-Negative Bacteria in a Referral Hospital, Saudi Arabia

Background

Emergence of pathogenic bacteria carrying β-lactamase-resistant determinants has become a major health problem in the hospital setting. The study aimed to determine antibiotic-resistant patterns and frequency of extended-spectrum β-lactamase- (ESBL-) producing Gram-negative bacteria (GNB) and AmpC β-lactamase-producing GNB.

Methodology

A prospective cross-sectional study was conducted during a period from September 2017 to August 2018 at King Abdullah Hospital, Bisha Province, Saudi Arabia. GNB (n = 311) were recovered from patients' clinical specimens including sputum, urine, wound pus, blood, tracheal aspirates and high vaginal swabs, umbilical discharge, eye discharge, and cerebrospinal fluids. Isolates were identified by the Phoenix identification system. Antimicrobial susceptibility was tested by the Kirby–Bauer disk procedure. Phenotypic characterization of ESBLs and AmpC β-lactamases was performed utilizing the double-disk synergy test and inhibitor-based method, respectively. Associations with outcome measures were determined by simple descriptive statistics and a chi-square test.

Results

Out of 311 GNB isolates, the frequency of ESBL and AmpC β-lactamase producers was 84 (27%) and 101 (32.5%), respectively. Klebsiella pneumoniae and Escherichia coli were common ESBL producers. AmpC β-lactamases predominate among Acinetobacter spp. and Pseudomonas aeruginosa. Coproduction of ESBLs and AmpC β-lactamases was found in 36 (11.6%) isolates, with very close relative frequencies among K. pneumoniae, Acinetobacter spp., and P. aeruginosa. β-Lactamase producers were predominantly found in the surgical department (56.5%) and ICUs (44.2%). ESBL producers revealed high resistance for cefuroxime (96.4%), cefotaxime (92.9%), and trimethoprim/sulfamethoxazole (90.5%). The resistance rates were significantly higher among ESBL producers than nonproducers for cephalosporins (p < 0.001), amoxicillin/clavulanate (p < 0.001), piperacillin/tazobactam (p = 0.010), nitrofurantoin (p = 0.027), aztreonam (p < 0.001), ciprofloxacin (p = 0.002), and trimethoprim/sulfamethoxazole (p < 0.001). Significantly higher (p < 0.05) resistance rates were observed among AmpC β-lactamase producers than nonproducers for all tested antibiotics.

Conclusions

This finding showed a high prevalence of ESBL- and AmpC β-lactamase-producing GNB in our hospital. Quality control practice and routine detection of β-lactamase producers before deciding on antibiotic therapy are advocated.

Plasmids carrying DHA-1 β-lactamases

The aim of this review is to provide an update on the plasmids mediating DHA-1 cephalosporinase in Klebsiella pneumoniae. These plasmids have been mainly found in this bacterium but not only. The first was isolated from Salmonella sp. in France in the early 1990s. They are currently reported worldwide. Bla_DHA-1 beta-lactamase gene is usually co-expressed with many other antibiotic resistance genes such as extended-spectrum β-lactamases (bla_CTX-M-, bla _SHV -types), oxacillinases (bla_OXA-1, bla_OXA-30), penicillinases (bla _TEM -type), carbapenemases (bla _OXA48 , bla_KPC-2), aminoglycosides (aacA, aadA, armA), fluoroquinolones (qnrB4, aac6'-1b-cr), and sulfonamide (sul1) resistance genes. Plasmids carrying DHA-1 cephalosporinase have different sizes (22 to 313 kb), belong to diverse groups of incompatibility (R, L/M, FII(k), FIB, A/C2, HI2, HIB), and are self-transferable or not. The multidrug resistance region consists of a mosaic structure composed of resistance genes, insertion sequences, composite transposon, and integrons.

Phenotypic and Molecular Characterization of Plasmid Mediated AmpC among Clinical Isolates of Klebsiella pneumoniae Isolated from Different Hospitals in Tehran

INTRODUCTION

Klebsiella pneumoniae is one of the main opportunistic pathogens which can cause different types of infections. Production of beta-lactamases like AmpC and ESBL mostly lead to beta-lactam resistance in these Gram-Negative bacteria. The aim of this study was the detection of AmpC-producing K. pneumoniae in clinical isolates.

MATERIALS AND METHODS

Three hundred and three isolates of K. pneumoniae were identified. Double disc method including cefoxitin with cefepime and using boronic acid with cloxacillin were performed as two phenotypic methods for detection of AmpC. Amplification of AmpC gene was performed by PCR.

RESULTS

Eight and three isolates showed positive results in double disc method and by using boronic acid with cloxacillin, respectively. Five isolates had specific band for AmpC gene after electrophoresis.

CONCLUSION

Our results were indicated the low prevalence of AmpC-producer-K. pnemoniae in Iran. On the other hand these two tested phenotypic methods showed low sensitivity for detection of AmpC.