ESBL Detection: Comparison of a Commercially Available Chromogenic Test for Third Generation Cephalosporine Resistance and Automated Susceptibility Testing in Enterobactericeae

Innovative approaches in phenotypic beta-lactamase detection for personalised infection management

Beta-lactamase-producing Enterobacteriaceae present a significant therapeutic challenge. Current developments in phenotypic diagnostics focus primarily on rapid minimum inhibitory concentration (MIC) determination. There is a requirement for rapid phenotypic diagnostics to improve antimicrobial susceptibility tests (AST) and aid prescribing decisions. Phenotypic AST are limited in their ability to characterise beta-lactamase-producing Enterobacteriaceae in detail. Despite advances in rapid AST, gaps and opportunities remain for developing additional diagnostic approaches that facilitate personalised antimicrobial prescribing. In this perspective, we highlight the state-of-the-art in beta-lactamase detection, identify gaps in current practice, and discuss barriers for innovation within this field.

Rapid and automated screening of carbapenemase- and ESBL-producing Gram-negative bacteria from rectal swabs using chromogenic agar media and the ScanStation device

The ScanSation 100 device (Interscience, France) is an incubator allowing real-time detection of bacterial colony growth by frequently imaging agar plates over time, counting CFU, and detecting colony color. This study evaluated its performance for the early detection of carbapenemase-producing bacteria (CPB) and extended-spectrum β-Lactamase-producing bacteria (ESBL-PB) from rectal swabs inoculated on CHROMagar mSuperCARBA and ESBL media, respectively. Rectal screening ESwabs collected from patients admitted to Grenoble University Hospital between January and June 2021 were analyzed. After inoculation, chromogenic media were incubated for 24 h in the automaton, with image acquisition every 30 min. ScanStation results were compared to visual observations of the plates after 24 h of incubation. In total, 501 rectal swabs were tested. ScanStation showed 100% positive percent agreement (PPA) for the detection of CPB and ESBL-PB, whereas the PPA of color categorization ranged between 45% and 100%. Negative percent agreement (NPA) ranged between 70% and 98%. Negative predictive values (NPVs) were 100% for both bacterial groups, whereas positive predictive values (PPVs) were 70.3% for CPB and 81.0% for ESBL-PB. Importantly, real-time screening allowed detection of the first suspected colony within 10-14 h of growth, on average, whereas visual observation is usually only performed once a day after 18-24 h of incubation. Our study demonstrates the potential use of early images to accelerate the detection of CPB and ESBL-PB and implement effective and timely infection control measures. IMPORTANCE The ScanStation 100 device is an incubator able to follow the real-time growth of bacterial colonies on agar plates through digital imaging, allowing users to sort plates according to the presence or absence of colonies, and to distinguish their color using four numeric color filters. Real-time screening shows that first colony detection is possible much earlier (after 10-14 h of growth, on average), whereas visual observation is usually performed only once a day after 18-24 h of incubation. The ScanStation device, combined with chromogenic agar media, is an efficient automated screening method to accelerate the detection of Gram-negative multidrug-resistant bacteria in laboratories that do not have access to larger laboratory automation systems. Our study shows that setting the image acquisition to one or two early images may allow for the detection of positive samples that were inoculated in the morning, by the end of the working day.

EVALUATION OF PHENOTYPIC AND MOLECULAR TECHNIQUE IN THE DETECTION OF EXTENDED SPECTRUM BETA-LACTAMASE (ESBL)-PRODUCING GRAM NEGATIVE BACILLI IN OGUN STATE, NIGERIA

Background

Molecular diagnosis though faster and more sensitive than phenotypic techniques, is more expensive. Resource limited settings are thus limited to using more of phenotypic rather than molecular methods in the routine detection of Extended Spectrum beta lactamases (ESBL).

Aim

This study aimed to evaluate the performance of double disc synergy test (DSST) and Epsilometer (E) test with Polymerase Chain Reaction (PCR) and to detect the risk factors associated with ESBL producing organisms among in-patients at Babcock University Teaching Hospital, Ilishan-Remo, Nigeria.

Methodology

Hospital-based cross-sectional study in which bacterial isolates of 165 in-patients were collected fromMarch 2018 to September 2019. The isolates were evaluated for ESBL production by the use of DDST, Etest and PCR. The performance evaluation was done. Questionnaire was used to assess the risk factors associated with ESBL, IBM SPSS Version 23 was used to analyze the data.

Results

The participants' isolates yielded 50/165 (30.3%) that were ESBL positive by DDST, 47/165 (28.9%) by E-test and 48/165(29.1%) by PCR. Sensitivity and specificity of DSST was 100% and 98.3% while that of E-test was 98% and 100% respectively. Age, antibiotics intake without prescription, being on ventilator, urethral catheterization and nasogastric tubes were all significantly associated with presence of ESBL (p value <0.05).

Conclusion

Phenotypic tests remain reliable for the routine detection of ESBL in the absence of molecular methods. Rational use of instrumentation and antibiotics is advocated based on the risk factors detected from this study.

Extended-spectrum β-lactamases: an update on their characteristics, epidemiology and detection

Extended-spectrum β-lactamase (ESBL)-producing Gram-negative pathogens are a major cause of resistance to expanded-spectrum β-lactam antibiotics. Since their discovery in the early 1980s, they have spread worldwide and an are now endemic in Enterobacterales isolated from both hospital-associated and community-acquired infections. As a result, they are a global public health concern. In the past, TEM- and SHV-type ESBLs were the predominant families of ESBLs. Today CTX-M-type enzymes are the most commonly found ESBL type with the CTX-M-15 variant dominating worldwide, followed in prevalence by CTX-M-14, and CTX-M-27 is emerging in certain parts of the world. The genes encoding ESBLs are often found on plasmids and harboured within transposons or insertion sequences, which has enabled their spread. In addition, the population of ESBL-producing Escherichia coli is dominated globally by a highly virulent and successful clone belonging to ST131. Today, there are many diagnostic tools available to the clinical microbiology laboratory and include both phenotypic and genotypic tests to detect β-lactamases. Unfortunately, when ESBLs are not identified in a timely manner, appropriate antimicrobial therapy is frequently delayed, resulting in poor clinical outcomes. Several analyses of clinical trials have shown mixed results with regards to whether a carbapenem must be used to treat serious infections caused by ESBLs or whether some of the older β-lactam-β-lactamase combinations such as piperacillin/tazobactam are appropriate. Some of the newer combinations such as ceftazidime/avibactam have demonstrated efficacy in patients. ESBL-producing Gram-negative pathogens will continue to be major contributor to antimicrobial resistance worldwide. It is essential that we remain vigilant about identifying them both in patient isolates and through surveillance studies.

Paper-based analytical devices for colorimetric detection of S. aureus and E. coli and their antibiotic resistant strains in milk

Animal derived milk which is an important part of human diet due to its high nutritional value not only supports humans but also presents a growth environment for pathogenic bacteria. Milk may become contaminated with bacteria through udder infections or through contact within the dairy farm environment. Infections are treated with antibiotics, with β-lactams most commonly used in veterinary medicine. However, their frequent use leads to the emergence of β-lactam resistant bacterial strains, which causes difficulties in the treatment of infections in both humans and animals. Detection of pathogens as well as their antibiotic sensitivity is a pre-requisite for successful treatment and this is generally achieved with laboratory-based techniques such as growth inhibition assays, enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCRs), which are unavailable in resource-limited settings. Here, we investigated paper-based analytical devices (μPADs) for the presumptive detection of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and their antibiotic resistant bacterial strains in milk samples. The μPADs were fabricated on filter paper using wax printing, and then impregnated with chromogenic substrates, which reacted with bacterial enzymes to form coloured products. Limits of detection of S. aureus and E. coli and their antibiotic resistant strains in milk samples were found to be 106 cfu mL-1. Enrichment of milk samples in a selective medium for 12 h enabled detection as low as 10 cfu mL-1. The paper devices tested on a set of 640 milk samples collected from dairy animals in Pakistan demonstrated more than 90% sensitivity and 100% selectivity compared to PCR, showing promise to provide inexpensive and portable diagnostic solutions for the detection of pathogenic bacteria in resource-limited settings.

Clinical outcomes of urinary tract infection caused by extended spectrum beta-lactamase producing Enterobacteriaceae: a retrospective observational study comparing patients with and without systemic inflammatory response syndrome

Aim

In severe urinary tract infection (UTI), susceptible antibiotics should be given. With the recent increase of multidrug‐resistant bacteria, especially extended spectrum beta‐lactamase producing Enterobacteriaceae (ESBL‐E), broad‐spectrum antibiotics, such as carbapenems, are used more frequently, which could lead to a further increase of multidrug‐resistant bacteria. We aimed to analyze the relationship between initial empirical antibiotic appropriateness and clinical outcomes in UTI, especially in patients with systemic inflammatory response syndrome (SIRS) and ESBL‐E.

Methods

A retrospective observational study from 2012 to 2017.

Results

Among urine culture‐positive cases with ≥10⁵ colony‐forming units/mL (n = 1,880), true UTI cases were extracted (n = 844) and divided into the SIRS group (n = 336 [ESBL‐E12.8% (43/336)]) and non‐SIRS group (n = 508 [ESBL‐E12.6% (64/508)]). In the SIRS ESBL‐E group, the initial antibiotics were susceptible in 55.8% (24/43), among which 91.7% (22/24) improved and 8.3% (2/24) deteriorated or died. The initial antibiotics were resistant in 44.2% (19/43), among which 47.4% (9/19) improved with the initial antibiotics, 47.4% (9/19) improved after escalating antibiotics, and 5.3% (1/19) deteriorated or died. In the SIRS group, 14 cases had true bacteremia with ESBL‐E. Seven cases were initiated with inappropriate antibiotics; four cases showed improvement before or without antibiotic change and three cases improved after antibiotic escalation.

Conclusion

Initiation of narrow‐spectrum antibiotics in septic UTI with ESBL‐E might not deteriorate the clinical outcome if promptly escalated on clinical deterioration or with ESBL‐E culture results. Further investigation is warranted to guide judicious use of initial antibiotics.

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and urinary tract infections in pregnant/postpartum women: A systematic review and meta-analysis

BACKGROUND

Urinary tract infections (UTI) and asymptomatic bacteriuria (AB) during pregnancy can result in considerable maternal and foetal adverse outcomes. Production of extended-spectrum beta-lactamase (ESBL) is a major antibiotic resistance mechanism by Enterobacteriaceae.

OBJECTIVES

To determine the global prevalence of ESBL-producing (ESBL-P) Enterobacteriaceae in symptomatic UTI/AB among pregnant/postpartum females.

DATA SOURCES

A systematic review of the PubMed, Embase, Scopus, WOS (Web of Science), ProQuest and the grey literature was conducted.

STUDY SELECTION AND DATA EXTRACTION

Studies that reported the frequency of ESBL-P Enterobacteriaceae in pregnant/postpartum women with UTI and/or AB were eligible. First, the titles and abstracts of the retrieved articles were reviewed. Then, the full texts of the remained articles were reviewed.

SYNTHESIS

In order to estimate the pooled prevalence and the 95% confidence interval (95% CI), meta-analysis was performed using the random-effects model.

RESULTS

Twenty-three studies (six from Africa, two from North America, one from South America, 12 from Asia and two European studies) that reported data on 20 033 Enterobacteriaceae strains were included. The pooled prevalence of ESBL-P Enterobacteriaceae was 25% (95% CI 18%, 32%); I2  = 98.8%. The estimated prevalence (95% CI) rates were 45% (22, 67%) in Africa, 33% (22, 44%) in India, 15% (6, 24%) in other Asian countries, 5% (2, 8%) in Europe, 4% (1, 11%) in South America and 3% (1, 5%) in North America (P < .001). This estimate was 21% (95% CI 11, 31%) in patients with symptomatic UTI and it was 28% (95% CI 15, 41%) in patients with AB (P = .40).

CONCLUSIONS

The prevalence of ESBL-P Enterobacteriaceae among pregnant women with UTI/AB was significant and geographic region was a major source for heterogeneity. The findings could be taken into account by healthcare providers and programmers in the management and antibiotic selection of UTI/AB during pregnancy, especially in high prevalence areas.

Current antimicrobial susceptibility testing for beta-lactamase-producing Enterobacteriaceae in clinical settings

The worldwide prevalence of beta-lactamase-producing Enterobacteriaceae (BL-E) is increasing. Bacterial infections involving ESBLs can be more difficult to treat because of antibiotic resistance, as there are fewer effective antibiotics left to be used. Moreover, treatment failure is often observed. Thus, quick and accurate identification of β-lactamases is imperative to minimize it. This review article describes most commonly used phenotypic techniques and molecular methods for the detection of ESBLs, acquired AmpC β-lactamases, and carbapenemases produced by Enterobacteriaceae. Phenotypic detection tests remain useful and relevant in clinical laboratories while molecular diagnostic methods are less affordable, more technically demanding, and not standardized. Molecular methods could be used to speed up results of bacterial antibiotic resistance or to clarify the results of phenotypic β-lactamases confirmation tests.

Correction: ESBL Detection: Comparison of a Commercially Available Chromogenic Test for Third Generation Cephalosporine Resistance and Automated Susceptibility Testing in Enterobactericeae

[This corrects the article DOI: 10.1371/journal.pone.0160203.].

High Heterogeneity of Escherichia coli Sequence Types Harbouring ESBL/AmpC Genes on IncI1 Plasmids in the Colombian Poultry Chain

Background

Escherichia coli producing ESBL/AmpC enzymes are unwanted in animal production chains as they may pose a risk to human and animal health. Molecular characterization of plasmids and strains carrying genes that encode these enzymes is essential to understand their local and global spread.

Objectives

To investigate the diversity of genes, plasmids and strains in ESBL/AmpC-producing E. coli from the Colombian poultry chain isolated within the Colombian Integrated Program for Antimicrobial Resistance Surveillance (Coipars).

Methods

A total of 541 non-clinical E. coli strains from epidemiologically independent samples and randomly isolated between 2008 and 2013 within the Coipars program were tested for antimicrobial susceptibility. Poultry isolates resistant to cefotaxime (MIC ≥ 4 mg/L) were screened for ESBL/AmpC genes including bla_CTX-M, bla_SHV, bla_TEM, bla_CMY and bla_OXA. Plasmid and strain characterization was performed for a selection of the ESBL/AmpC-producing isolates. Plasmids were purified and transformed into E. coli DH10B cells or transferred by conjugation to E. coli W3110. When applicable, PCR Based Replicon Typing (PBRT), plasmid Multi Locus Sequence Typing (pMLST), plasmid Double Locus Sequence Typing (pDLST) and/or plasmid Replicon Sequence Typing (pRST) was performed on resulting transformants and conjugants. Multi Locus Sequence Typing (MLST) was used for strain characterization.

Results

In total, 132 of 541 isolates were resistant to cefotaxime and 122 were found to carry ESBL/AmpC genes. Ninety-two harboured bla_CMY-2 (75%), fourteen bla_SHV-12 (11%), three bla_SHV-5 (2%), five bla_CTX-M-2 (4%), one bla_CTX-M-15 (1%), one bla_CTX-M-8 (1%), four a combination of bla_CMY-2 and bla_SHV-12 (4%) and two a combination of bla_CMY-2 and bla_SHV-5 (2%). A selection of 39 ESBL/AmpC-producing isolates was characterized at the plasmid and strain level. ESBL/AmpC genes from 36 isolates were transferable by transformation or conjugation of which 22 were located on IncI1 plasmids. These IncI1 plasmids harboured predominantly bla_CMY-2 (16/22), and to a lesser extend bla_SHV-12 (5/22) and bla_CTX-M-8 (1/22). Other plasmid families associated with ESBL/AmpC-genes were IncK (4/33), IncHI2 (3/33), IncA/C (2/33), IncΒ/O (1/33) and a non-typeable replicon (1/33). Subtyping of IncI1 and IncHI2 demonstrated IncI1/ST12 was predominantly associated with bla_CMY-2 (12/16) and IncHI2/ST7 with bla_CTX-M-2 (2/3). Finally, 31 different STs were detected among the 39 selected isolates.

Conclusions

Resistance to extended spectrum cephalosporins in E. coli from Colombian poultry is mainly caused by bla_CMY-2 and bla_SHV-12. The high diversity of strain Sequence Types and the dissemination of homogeneous IncI1/ST12 plasmids suggest that spread of the resistance is mainly mediated by horizontal gene transfer.