External quality assessment schemes in bacteriology support public health in Germany-results from 2006 to 2023.

External Quality Assessment schemes (EQAS) are mandatory to ensure quality standards in diagnostic methods and achieve laboratory accreditation. As host institution for two German culture-based bacteriology EQAS (RV-A and RV-B), we investigated the obtained data of 590 up to 720 surveys per year in RV-A and 2,151 up to 2,929 in RV-B from 2006 to 2023. As educational instruments, they function to review applied methodology and are valuable to check for systemic- or method-dependent failures in microbiology diagnostics or guidelines. Especially, containment of multi-resistant bacteria in times of rising antibiotic resistance is one major point to assure public health. The correct identification and reporting of these strains is therefore of high importance to achieve this goal. Moreover, correct antimicrobial susceptibility testing (AST) per se is important for selecting appropriate therapy, to restrict broad-spectrum antibiotics and minimize resistance development. The reports of participating laboratories displayed a high level of correct identification results in both schemes with mostly consistent failure rates around 2.2% (RV-A) and 3.9% (RV-B) on average. In contrast, results in AST revealed increasing failure rates upon modification of AST requirements concerning adherence to standards and subsequent bacterial species-specific evaluation. Stratification on these periods revealed in RV-A a moderate increase from 1.3% to 4.5%, while in RV-B failure rates reached 14% coming from 4.3% on average. Although not mandatory, subsequent AST evaluation and consistent reporting are areas of improvement to benefit public health.

Maximally stable extremal regions-based algorithm for automatic interpretation of disc-diffusion antibiotic sensitivity test.

Antibiotic resistance causes a major threat to patients suffering from infectious diseases. Accurate and timely assessment of Antibiotic Susceptibility Test (AST) is of great importance to ensure adequate treatment for patients and for epidemiological monitoring. Disc Diffusion Test (DDT) is a standard and widely used method for AST. Manual interpretation of DDT results is a tedious task and susceptible to human errors. Computer vision-based automated interpretation of DDT results will speed up the process and reduces the manpower requirement. This would assist the physician to initiate the antibiotic treatment for the patients on time and results in saving the patient's life. The crucial step in automatic interpretation of DDT result is to measure and present the diameter of zone of inhibition without manual intervention. The existing methods require manual interventions at various stages during inhibition zone diameter measurement for some typical cases. This issue is addressed in the present work through maximally stable extremal regions (MSER) based algorithm. Dataset consisting of 60 agar plate images that includes different agar medium, images having different resolution and visual quality is used to validate the proposed method. Experimental results demonstrated that there is a strong correlation between standard method and the proposed method.

Micro-flow cell washing technique combined with single-cell Raman spectroscopy for rapid and automatic antimicrobial susceptibility test of pathogen in urine.

Facing the rapid spread of antimicrobial resistance, methods based on single-cell Raman spectroscopy have proven their advances in reducing the turn-around time (TAT) of antimicrobial susceptibility tests (AST). However, the Raman-based methods are still hindered by the prolonged centrifugal cell washing procedure, which may require complex labor operation and induce high mechanical stress, resulting in a pretreatment time of over 1 h as well as a high cell-loss probability. In this study, we developed a micro-flow cell washing device and corresponding Raman-compatible washing chips, which were able to automatically remove the impurities in the samples, retain the bacterial cell and perform Raman spectra acquisition in situ. Results of washing the 5- and 10-µm polymethyl methacrylate (PMMA) microspheres showed that the novel technique achieved a successful removal of 99 % impurity and an 80 % particle retention rate after 6 to 10 cycles of washing. The micro-flow cell washing technique could complete the pretreatment for urine samples in a 96-well plate within 10 min, only taking 15 % of the handling time required by centrifugation. The AST profiles of urine sample spiked with E. coli 25922, E. faecalis 29212, and S. aureus 29213 obtained by the proposed Raman-based approach were found to be 100 % consistent with the results from broth micro-dilution while reducing the TAT to 3 h from several days which is required by the latter. Our study has demonstrated the micro-flow cell washing technique is a reliable, fast and compatible approach to replace centrifuge washing for sample pretreatment of Raman-AST and could be readily applied in clinical scenarios.

A retrospective study of uropathogen and its antibiotic resistance among children with urinary tract infection from a single center in China.

Urinary tract infection (UTI) is a well-known bacterial infection posing serious health problem in children. A retrospective study was conducted to explore the uropathogen and its antibiotic resistance in children with UTI. Data of urine culture and antimicrobial susceptibility test was collected. Consequently, 840 children were included. The overall culture-positive UTI was 458 (54.52 %) with Escherichia coli 166 (36.24 %), followed by Enterococcus faecalis 59 (12.88 %), Enterococcus faecium 70 (15.28 %) and others. They were highly resistant to the most commonly used antibiotics. In 694 children with complicated UTI, there were 8 children with fungal infection. Multiple drug resistance (MDR) was recorded in 315 (80.98 %). The overall proportion of Extended Spectrum ß-Lactamase (ESßL) production was 25 (6.43 %). In 146 children with simple UTI, MDR were also detected in 47 (77.05 %). There were 6 (9.84 %) positive for ESßL production. Our study found that complicated UTI was relatively common. Escherichia coli was the most prevalent isolate, followed by Enterococcus faecium and Enterococcus faecalis. These organisms were highly resistant to the most commonly used antibiotics. Relatively high prevalence of MDR and low ESßL-producing organisms were observed.

Care practices of contact lens solutions and microbial contamination among wearers in Ghana.

PURPOSE: This study sought to assess contact lens solutions care practices, and their microbial contamination among contact lens wearers in Ghana and to profile their antibiotic susceptibility pattern. METHODS: The study employed a biphasic approach which involved a cross-sectional design that investigated participants' habits related to care for the solutions with a two-part questionnaire and a microbiological analysis of samples of contact lens care solutions of the participants for microbial contamination. A snowball sampling method provided access to 32 different contact lens wearers in four care facilities in Ghana. In most cases, the participants had no pre-existing familial relationship with each other or with the care facilities. RESULTS: Out of 32 samples of contact lens solutions, 30 were tested for microbial contamination. A total of 23 (76.67 %) samples of contact lens solution were found to be contaminated with Enterobacter sp. (34.80 %), Pseudomonas sp. (21.70 %), Bacilli sp. (21.70 %), Klebsiella sp. (17.20 %), and Escherichia coli (4.60 %). The duration of solution storage in the open bottle and nonadherence to manufacturer instructions for solution storage showed a statistically significant association with microbial contamination (p ≤ 0.05). CONCLUSION: Contact lens care solutions have been found to harbour multiple antibiotic-resistant bacteria that are potentially pathogenic to the corneal surface. The contamination is associated with some unhealthy solution-care practices among wearers.

Case report: Omphalitis caused by Trueperella pyogenes infection in a Korean indigenous calf.

Omphalitis, commonly caused by opportunistic bacteria has been significantly associated with morbidity and mortality in neonatal calves. Trueperella pyogenes is a commensal and opportunistic pathogen that can cause suppurative infection in farm animals. Our case involved a 10-day-old female Korean indigenous calf that presented with umbilical enlargement accompanied by a greenish-yellow purulent discharge and right forelimb lameness. The calf was diagnosed with failure of passive transfer at 24 h of age. Physical examination found hypothermia (38.1°C), tachycardia (110 beats/min), tachypnea (47 cycles/min), and open mouth breathing. Ultrasonography revealed hyperechoic pus in the 9th and 10th right intercostals, for which a liver abscess due to omphalophlebitis was suspected. After 3 days, the calf died. T. pyogenes was detected in the umbilical cord, lung, liver, kidney, intestine, mesenteric lymph node, urinary bladder, and bladder ligament. All genes related to the virulent factors (i.e., plo, cbpA, fimA, fimC, fimG, nanH, and nanP) were also identified, with plo and fimA being associated with pathogenicity. A final diagnosis of omphalitis was established based on the identification of virulent T. pyogenes and umbilical cord dilatation on ultrasonography. Antimicrobial susceptibility tests showed that the isolated T. pyogenes was susceptible to amoxicillin, ceftiofur, florfenicol, enrofloxacin, ofloxacin, and ciprofloxacin, suggesting the suitability of these antibiotics for treating T. pyogenes-induced omphalitis. Hence, accurate and rapid diagnosis of the involved bacteria and antimicrobial susceptibility patterns can help guide therapeutic decisions. Our case provides useful information that could aid large animal clinicians in the diagnosis and treatment of T. pyogenes-induced omphalitis.

Membranome-based identification of amino acid substitution in Haemophilus influenzae multidrug efflux pump HmrM for reduced chloramphenicol susceptibility.

A decreased chloramphenicol susceptibility in Haemophilus influenzae is commonly caused by the activity of chloramphenicol acetyltransferases (CATs). However, the involvement of membrane proteins in chloramphenicol susceptibility in H. influenzae remains unclear. In this study, chloramphenicol susceptibility testing, whole-genome sequencing, and analyses of membrane-related genes were performed in 51 H. influenzae isolates. Functional complementation assays and structure-based protein analyses were conducted to assess the effect of proteins with sequence substitutions on the minimum inhibitory concentration (MIC) of chloramphenicol in CAT-negative H. influenzae isolates. Six isolates were resistant to chloramphenicol and positive for type A-2 CATs. Of these isolates, A3256 had a similar level of CAT activity but a higher chloramphenicol MIC relative to the other resistant isolates; it also had 163 specific variations in 58 membrane genes. Regarding the CAT-negative isolates, logistic regression and receiver operator characteristic curve analyses revealed that 48T > G (Asn16Lys), 85 C > T (Leu29Phe), and 88 C > A (Leu30Ile) in HI_0898 (emrA), and 86T > G (Phe29Cys) and 141T > A (Ser47Arg) in HI_1177 (artM) were associated with enhanced chloramphenicol susceptibility, whereas 997G > A (Val333Ile) in HI_1612 (hmrM) was associated with reduced chloramphenicol susceptibility. Furthermore, the chloramphenicol MIC was lower in the CAT-negative isolates with EmrA-Leu29Phe/Leu30Ile or ArtM-Ser47Arg substitution and higher in those with HmrM-Val333Ile substitution, relative to their counterparts. The Val333Ile substitution was associated with enhanced HmrM protein stability and flexibility and increased chloramphenicol MICs in CAT-negative H. influenzae isolates. In conclusion, the substitution in H. influenzae multidrug efflux pump HmrM associated with reduced chloramphenicol susceptibility was characterised.

Unexpected decrease in necrotizing enterocolitis morbidity during the COVID-19 pandemic-A single-centre retrospective study.

Background: The impact of the coronavirus disease 2019 (COVID-19) pandemic on neonatal necrotizing enterocolitis (NEC) is not well characterised. This cross-sectional study evaluated the potential effects of pandemic-related measures on NEC morbidity in premature infants in a neonatal ward during the COVID-19 pandemic. Methods: This was a retrospective study conducted in a tertiary neonatal ward in eastern and central China over 6 consecutive years (2017, 2018, 2019, 2020, 2021 and 2022). The medical records of 189 premature infants with stage II or III NEC were reviewed for clinical manifestations and aetiologies. The data were analysed and compared between the prepandemic period (2017, 2018, and 2019) and the pandemic period (2020, 2021 and 2022). Results: A total of 9,903 infants with gestational age (GA) < 37 weeks were enrolled, including 5,382 in the prepandemic period and 4,521 in the pandemic period. A reduction in stage II or III NEC morbidity was observed in infants with GA < 37 weeks, with an average annual morbidity of 2.29% (123/5,382) (95% CI, 1.89%-2.68%) in the prepandemic period and 1.46% (66/4,521) (95% CI, 1.11%-1.81%) in the pandemic period. NEC morbidity showed resurgent characteristics in 2021. When prepandemic coinfections were excluded, most cases of NEC with bloodstream infections in the prepandemic period were attributable to Gram-negative bacteria (27/32, 84.38%), mainly Klebsiella pneumoniae, while in the pandemic period they were attributable to Gram-positive bacteria (10/18, 55.56%), mainly Staphylococcus aureus. Antimicrobial susceptibility testing revealed that Klebsiella pneumoniae was 100% sensitive to meropenem, imipenem, ciprofloxacin and levofloxacin and 100% resistant to ampicillin. Staphylococcus capitis was 100% sensitive to vancomycin, linezolid, tetracycline, cotrimoxazole and cefoxitin and 100% resistant to penicillin and benzathine. Conclusions: COVID-19 pandemic-related interventions can reduce the morbidity of NEC and change the pathogen spectrum in patients with bloodstream infections. We need to understand the exact factors leading to these changes.

Comparison of available methods to evaluate cefiderocol susceptibility in Acinetobacter spp.

Recently, considerable uncertainty has arisen concerning the appropriate susceptibility testing for cefiderocol in gram-negative bacilli, particularly in the context of its application to Acinetobacter spp. The optimal method for assessing the susceptibility levels of Acinetobacter spp. to cefiderocol remains a subject of debate due to substantial disparities observed in the values obtained through various testing procedures. This study employed four minimum inhibitory concentration (MIC) methodologies and the disk diffusion to assess the susceptibility of twenty-seven carbapenem resistant (CR)-Acinetobacter strains to cefiderocol. The results from our study reveal significant variations in the minimum inhibitory concentration (MIC) values obtained with the different methods and in the level of agreement in interpretation categories between the different MIC methods and the disk diffusion test. Among the MIC methods, there was relatively more consistency in reporting the interpretation categories. For European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, the categorical agreement (CA) for MIC methods ranged between 66.7 and 81.5%. On the other hand, the essential agreement (EA) values were as low as 18.5-29.6%. The CA between MIC methods and disk diffusion was 81.5%. These results emphasize the need for a reliable, accurate, and clinically validated methodology to effectively assess the susceptibility of Acinetobacter spp. to cefiderocol. The wide variability observed in our study highlights the importance of standardizing the susceptibility testing process for cefiderocol to ensure consistent and reliable results for clinical decision-making.

Prevalence of Helicobacter pylori resistance to certain antibiotics at An-Najah University Hospital: a cross-sectional study.

Antibiotic resistance among bacteria is recognized as the primary factor contributing to the failure of treatment. In this research, our objective was to examine the prevalence of antibiotic resistance in H. pylori bacteria in Palestine. We enlisted 91 individuals suffering from dyspepsia, comprising 49 females and 42 males. These participants underwent esophagogastroduodenoscopy procedures with gastric biopsies. These biopsies were subsequently subjected to microbiological assessments and tested for their susceptibility to various antimicrobial drugs. Among the 91 patients, 38 (41.7%) exhibited the presence of H. pylori. Notably, Ciprofloxacin displayed the highest efficacy against H. pylori, followed by Levofloxacin, Moxifloxacin, and Amoxicillin, with resistance rates of 0%, 0%, 2.6%, and 18.4%, respectively. On the contrary, Metronidazole and Clarithromycin demonstrated the lowest effectiveness, with resistance percentages of 100% and 47.4%, respectively. The outcomes of this investigation emphasize that H. pylori strains within the Palestinian patient group exhibit substantial resistance to conventional first-line antibiotics like clarithromycin and metronidazole. However, alternative agents such as fluoroquinolones and amoxicillin remain efficacious choices. Consequently, we recommend favoring quinolone-based treatment regimens for H. pylori infections and adopting a more judicious approach to antibiotic usage among the Palestinian population.

European multi-centre study to establish MIC and zone diameter epidemiological cut-off values for Bacillusanthracis.

OBJECTIVES: Bacillus anthracis clinical breakpoints, representing a systematic approach to guide clinicians in selecting the most appropriate antimicrobial treatments, are not part of the guidance from the European Committee on Antimicrobial Susceptibility Testing (EUCAST). This is because defined distributions of MIC values and of epidemiological cut-off values (ECOFFs) have been lacking. In this study, a Europe-wide network of laboratories in collaboration with EUCAST, aimed at establishing standardized antimicrobial susceptibility testing methods, wild-type MIC distributions, and ECOFFs for ten therapeutically relevant antimicrobials. METHODS: About 335 B. anthracis isolates were tested by broth microdilution and disc diffusion methodologies. MIC and inhibition zone diameters were curated according to EUCAST SOP 10.2 and the results were submitted to EUCAST for ECOFFs and clinical breakpoint determination. RESULTS: Broth microdilution and disc diffusion data distributions revealed putative wild-type distributions for the tested agents. For each antimicrobial agent, ECOFFs were defined. Three highly resistant strains with MIC values of 32 mg/L benzylpenicillin were found. MIC values slightly above the defined ECOFFs were observed in a few isolates, indicating the presence of resistance mechanisms to doxycycline, tetracycline, and amoxicillin. DISCUSSION: B. anthracis antimicrobial susceptibility testing results were used by EUCAST to determine ECOFFs for ten antimicrobial agents. The MIC distributions were used in the process of determining clinical breakpoints. The ECOFFs can be used for the sensitive detection of isolates with resistance mechanisms, and for monitoring resistance development. Genetic changes causing phenotypic shifts in isolates displaying slightly elevated MICs remain to be investigated.

Short-term culture for rapid identification by mass spectrometry and automated antimicrobial susceptibility testing from positive bottles.

BACKGROUND: Early and appropriate antibiotic treatment improves the clinical outcome of patients with sepsis. There is an urgent need for rapid identification (ID) and antimicrobial susceptibility testing (AST) of bacteria that cause bloodstream infection (BSI). Rapid ID and AST can be achieved by short-term incubation on solid medium of positive blood cultures using MALDI-TOF mass spectrometry (MS) and the BD M50 system. The purpose of this study is to evaluate the performance of rapid method compared to traditional method. METHODS: A total of 124 mono-microbial samples were collected. Positive blood culture samples were short-term incubated on blood agar plates and chocolate agar plates for 5 ∼ 7 h, and the rapid ID and AST were achieved through Zybio EXS2000 MS and BD M50 System, respectively. RESULTS: Compared with the traditional 24 h culture for ID, this rapid method can shorten the cultivation time to 5 ∼ 7 h. Accurate organism ID was achieved in 90.6% of Gram-positive bacteria (GP), 98.5% of Gram-negative bacteria (GN), and 100% of fungi. The AST resulted in the 98.5% essential agreement (EA) and 97.1% category agreements (CA) in NMIC-413, 99.4% EA and 98.9% CA in PMIC-92, 100% both EA and CA in SMIC-2. Besides, this method can be used for 67.2% (264/393) of culture bottles during routine work. The mean turn-around time (TAT) for obtaining final results by conventional method is approximately 72.6 ± 10.5 h, which is nearly 24 h longer than the rapid method. CONCLUSIONS: The newly described method is expected to provide faster and reliable ID and AST results, making it an important tool for rapid management of blood cultures (BCs). In addition, this rapid method can be used to process most positive blood cultures, enabling patients to receive rapid and effective treatment.

Antibacterial activity of pigment extracted from bacteria isolated from soil samples.

The purpose of this study was to evaluate antibacterial activity of pigment extracted from bacteria, isolated from soil samples. During the study, 20 soil samples were collected from different areas (forest, agriculture fields, river sides and dumping sites) of Kathmandu and Lalitpur districts which were processed for isolation of pigment producing bacteria by spread plate technique. The pigmented bacterial isolates were identified and enriched in nutrient broth. Then, pigment was extracted in 95% methanol as solvent, which was further characterized using UV-Vis Spectrophotometric and TLC analysis. The obtained crude pigment extract was processed to carry out the antimicrobial susceptibility assay using agar well diffusion method. Out of 13 total pigmented bacteria isolates, four different colored pigmented bacterial isolates (S4O, S11Y, S14P and S17G) which produced efficient pigment on nutrient agar were chosen and they were further processed. Among these isolates, S4O was identified as Staphylococcus aureus, S11Y was identified as Micrococcus luteus, S14P was identified as Micrococcus roseus and S17G was identified as Pseudomonas aeruginosa respectively. On characterization using UV-Vis Spectrophotometric and TLC analysis, the pigment extracted from isolates S4O, S11Y and S14P were found to be Carotenoids and from isolate S17G was found to be Pyocyanin in nature. The maximum antibacterial activity was shown against Staphylococcus aureus from all the four pigments extracts. The green color pigment extract from isolate S17G was found to be most effective against all the Gram-positive and Gram-negative test bacteria. This study suggests that these pigment extracts from pigmented bacteria may have beneficial antibacterial roles that can be exploited in controlling unwanted bacterial growth.

Interactions between Aeromonas caviae and Yersinia enterocolitica isolated from a case of diarrhea: evaluation of antimicrobial susceptibility and immune response of infected macrophages.

Aeromonas species cause a wide spectrum of human diseases, primarily gastroenteritis, septicemia, and wound infections. Several studies have shown that about 40% of these cases involve mixed or polymicrobial infections between Aeromonas spp. and bacteria from other genera. However, the immune response of macrophages in front of the bacteria present in the mixed infections, as well as their impact on antimicrobial therapy, have not been investigated. This study evaluated the cell damage and immune response of the mouse macrophage BALB/c cell line (J774A.1) after performing a single and a mixed infection with a strain of Aeromonas caviae and Yersinia enterocolitica, both recovered from the same fecal sample from a patient with diarrhea. Macrophage cell damage was measured by the release of lactate dehydrogenase (LDH) while the immune response was evaluated studying the expression by RT-qPCR of six relevant immune-related genes. Additionally, the antimicrobial susceptibility pattern of the single and mixed strains in front of seventeen antibiotics was evaluated to determine the potential impact on the infection treatment. Macrophages infected with the mixture of the two strains showed a higher cell damage in comparison with the single infections and the immune-related genes, i.e., cytokines and chemokines genes (TNF-α, CCL20), and apoptotic and pyroptotic genes (TP53 and IL-1ß) were overexpressed. After infection with the mixed cultures, an increase in the antimicrobial resistance was observed for ciprofloxacin, trimethoprim, chloramphenicol, gentamicin and ertapenem. This study increased the knowledge about the synergetic effect of the bacteria involved in mixed infection and on their potential impact on the treatment and evolution of the infection.

Prevalence of multi-drug resistant bacteria in intensive care units at Tripoli University Hospital, Tripoli, Libya.

Among hospitalized patients worldwide, infections caused by multidrug-resistant (MDR) bacteria are a major cause of morbidity and mortality. This study aimed to isolate MDR bacteria from five intensive care units (ICUs) at Tripoli University Hospital (TUH). A prospective cross-sectional study was conducted over a seven-month period (September 2022 to March 2023) across five ICUs at TUH. A total of 197 swabs were collected from Patients', healthcare workers' and ICUs equipment. Samples collected from patients were nasal swabs, oral cavity swabs, hand swabs, sputum specimens, skin swabs, umbilical venous catheter swabs, and around cannula. Swabs collected from health care workers were nasal swabs, whereas ICUs equipment's samples were from endotracheal tubes, oxygen masks, and neonatal incubators. Identification and antimicrobial susceptibility test was confirmed by using MicroScan auto SCAN 4 (Beckman Coulter). The most frequent strains were Gram negative bacilli 113 (57.4%) with the predominance of Acinetobacter baumannii 50/113 (44%) followed by Klebsiella pneumoniae 44/113 (40%) and Pseudomonas aeruginosa 6/113 (5.3%). The total Gram positive bacterial strains isolated were 84 (42.6%), coagulase negative Staphylococci 55 (66%) with MDRs (89%) were the most common isolates followed by Staphylococcus aureus 15 (17.8%). Different antibiotics were used against these isolates; Gram- negative isolates showed high resistance rates to ceftazidime, gentamicin, amikacin and ertapenem. A. baumannii were the most frequent MDROs (94%), and the highest resistance rates in Gram-positive strains were observed toward ampicillin, oxacillin, ampicillin/sulbactam and Cefoxitin, representing 90% of total MDR Gram-positive isolates. ESBL and MRS were identified in most of strains. The prevalence of antibiotic resistance was high for both Gram negative and Gram positive isolates. This prevalence requires strict infection prevention and control intervention, continuous monitoring, implementation of effective antibiotic stewardship, immediate, concerted and collaborative action to monitor its prevalence and spread in the hospital.

Description of a pathogenic strain of Aeromonas dhakensis isolated from Ancherythroculter nigrocauda in an inland region of China.

Aeromonas dhakensis is reported as an emerging pathogenic species within the genus Aeromonas and is widely distributed in tropical coastal areas. This study provided a detailed description and characterization of a strain of A. dhakensis (202108B1) isolated from diseased Ancherythroculter nigrocauda in an inland region of China. Biochemical tests identified the isolate at the genus level, and the further molecular analysis of concatenated housekeeping gene sequences revealed that the strain belonged to the species A. dhakensis. The isolated A. dhakensis strain was resistant to five antibiotics, namely, penicillin, ampicillin, clindamycin, cephalexin and imipenem, while it was susceptible or showed intermediate resistance to most of the other fifteen tested antibiotics. The isolated strain of A. dhakensis caused acute haemorrhagic septicaemia and tissue damage in artificially infected A. nigrocauda, with a median lethal dose of 7.76×104 CFU/fish. The genome size of strain 202108B1 was 5043286 bp, including one chromosome and four plasmids. This is the first detailed report of the occurrence of infection caused by an A. dhakensis strain causing infection in an aquaculture system in inland China, providing important epidemiological data on this potential pathogenic species.

Rapid Direct Identification of Microbial Pathogens and Antimicrobial Resistance Genes in Positive Blood Cultures Using a Fully Automated Multiplex PCR Assay.

This study assessed the performance of the BioFire Blood Culture Identification 2 (BCID2) panel in identifying microorganisms and antimicrobial resistance (AMR) profiles in positive blood cultures (BCs) and its influence on turnaround time (TAT) compared with conventional culture methods. We obtained 117 positive BCs, of these, 102 (87.2%) were correctly identified using BCID2. The discordance was due to off-panel pathogens detected by culture (n = 13), and additional pathogens identified by BCID2 (n = 2). On-panel pathogen concordance between the conventional culture and BCID2 methods was 98.1% (102/104). The conventional method detected 19 carbapenemase-producing organisms, 14 extended-spectrum beta-lactamase-producing Enterobacterales, 18 methicillin-resistant Staphylococcus spp., and four vancomycin-resistant Enterococcus faecium. BCID2 correctly predicted 53 (96.4%) of 55 phenotypic resistance patterns by detecting AMR genes. The TAT for BCID2 was significantly lower than that for the conventional method. BCID2 rapidly identifies pathogens and AMR genes in positive BCs.

Multicenter comparison of Etest, Vitek2 and BD Phoenix to broth microdilution for beta-lactam susceptibility testing of Streptococcus pneumonia.

PURPOSE: To assess performance of Etest®, Vitek®2 and BD Phoenix™ to determine the susceptibility of Streptococcus pneumoniae strains to penicillin, ampicillin and cefotaxime. METHODS: Sixty unique S. pneumoniae challenge strains were selected to cover a wide range of penicillin, ampicillin and cefotaxime minimal inhibitory concentrations (MICs). Strains were analyzed in four different Belgian laboratories. Etest® benzylpenicillin (BEN), ampicillin/amoxicillin (AMP) and cefotaxime (CTA) (bioMérieux), Vitek®2 AST-ST03 (bioMérieux) and BD Phoenix™ SMIC/ID-11 testing were each performed in two different labs. Results were compared to Sensititre® broth microdilution (BMD) (Thermo Fisher Scientific) results. MIC results were interpreted using EUCAST non-meningitis breakpoints (v 13.0). RESULTS: Essential agreement (EA) was ≥ 90% for all methods compared to BMD, except for Etest® BEN on Oxoid plate (58.3%), Etest® AMP (both on Oxoid (65.8%) and BD BBL plate (84.2%)). Categorical agreement (CA) for penicillin was only ≥ 90% for Vitek®2, for other methods CA ranged between 74 and 84%. CA for AMP was for all methods < 90% (range 75.8-88.3%) and CA for CTA was between 87 and 90% for all methods except for Etest on Oxoid plate (79.2%). CONCLUSIONS: Our study indicates that Vitek®2 and BD Phoenix™ are reliable for providing accurate pneumococcal susceptibility results for BEN, AMP and CTA. Using Etest BEN or AMP on Oxoid plate carries a risk of underestimating the MIC and should be interpreted with caution, especially when the obtained MIC is 1 or 2 doubling dilutions below the S or R clinical breakpoint.

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: insights from a tertiary hospital in Southern Thailand.

Broad-spectrum ampicillin-resistant and third-generation cephalosporin-resistant Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae that have pathological features in humans, have become a global concern. This study aimed to investigate the prevalence, antimicrobial susceptibility, and molecular genetic features of extended-spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumoniae isolates in Southern Thailand. Between January and August 2021, samples (n = 199) were collected from a tertiary care hospital in Southern Thailand. ESBL and AmpC-lactamase genes were identified using multiplex polymerase chain reaction (PCR). The genetic relationship between ESBL-producing E. coli and K. pneumoniae was determined using the enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction. ESBL-producing E. coli and K. pneumoniae isolates were mostly collected from catheter urine samples of infected female patients. The ESBL production prevalence was highest in the medical wards (n = 75, 37.7%), followed by that in surgical wards (n = 64, 32.2%) and operating rooms (n = 19, 9.5%). Antimicrobial susceptibility analysis revealed that all isolates were resistant to ampicillin, cefotaxime, ceftazidime, ceftriaxone, and cefuroxime; 79.4% were resistant to ciprofloxacin; and 64.3% were resistant to trimethoprim-sulfamethoxazole. In ESBL-producing K. pneumoniae and E. coli, blaTEM (n = 57, 72.2%) and blaCTX-M (n = 61, 50.8%) genes were prominent; however, no blaVEB, blaGES, or blaPER were found in any of these isolates. Furthermore, only ESBL-producing K. pneumoniae had co-harbored blaTEM and blaSHV genes at 11.6%. The ERIC-PCR pattern of multidrug-resistant ESBL-producing strains demonstrated that the isolates were clonally related (95%). Notably, the presence of multidrug-resistant and extremely resistant ESBL producers was 83.4% and 16.6%, respectively. This study highlights the presence of blaTEM, blaCTX-M, and co-harbored genes in ESBL-producing bacterial isolates from hospitalized patients, which are associated with considerable resistance to beta-lactamase and third-generation cephalosporins. IMPORTANCE: We advocate for evidence-based guidelines and antimicrobial stewardship programs to encourage rational and appropriate antibiotic use, ultimately reducing the selection pressure for drug-resistant bacteria and lowering the likelihood of ESBL-producing bacterial infections.