{"title":"Quantification of Pseudomonas aeruginosa biofilms using electrochemical methods.","authors":"Lily Riordan, Perrine Lasserre, Damion Corrigan, Katherine Duncan","doi":"10.1099/acmi.0.000906.v4","DOIUrl":"10.1099/acmi.0.000906.v4","url":null,"abstract":"<p><p>Currently, 2.29% of deaths worldwide are caused by antimicrobial resistance (AMR), compared to 1.16% from malaria and 1.55% from human immunodeficiency virus and acquired immunodeficiency syndrome. Furthermore, deaths resulting from AMR are projected to increase to more than 10 million <i>per annum</i> by 2050. Biofilms are common in hospital settings, such as medical implants, and pose a particular problem as they have shown resistance to antibiotics up to 1000-fold higher than planktonic cells because of dormant states and reduced growth rates. This is compounded by the fact that many antibiotics target mechanisms of active metabolism and are therefore less effective. The work presented here aimed to develop a method for biofilm quantification, which could be translated into the clinical setting, as well as used in the screening of antibiofilm agents. This was carried out alongside crystal violet staining, as a published point of reference. This work builds upon work previously presented by Dunphy <i>et al.</i>, in which the authors attempted to quantify the biofilm formation of <i>Pseudomonas aeruginosa</i> strain using hyperspectral imaging. Here, using electrochemical impedance spectroscopy and square wave voltammetry, the biofilm formation of two <i>P. aeruginosa</i> strains was detected within an hour after seeding <i>P. aeruginosa</i> on the sensor. A 40% decrease in impedance modulus was shown when <i>P. aeruginosa</i> biofilm had formed, compared to the media-only control. As such, this work offers a starting point for the development of real-time biofilm sensing technologies, which can be translated into implantable materials.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11829079/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-02-14eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000709.v3
Izabela Moura Duin, Viviane Yumi Baba, Katherine M D'Amico-Willman, Fernanda Neves Paduan, Vanessa Hitomi Sugahara Rodrigues, Jose C Huguet-Tapia, Jeffrey Bryant Jones, Marcelo G Canteri, Rui Pereira Leite Júnior, Maria Isabel Balbi-Peña
{"title":"Genome sequences of pathogenic and non-pathogenic Pantoea ananatis strains in maize (Zea mays L.).","authors":"Izabela Moura Duin, Viviane Yumi Baba, Katherine M D'Amico-Willman, Fernanda Neves Paduan, Vanessa Hitomi Sugahara Rodrigues, Jose C Huguet-Tapia, Jeffrey Bryant Jones, Marcelo G Canteri, Rui Pereira Leite Júnior, Maria Isabel Balbi-Peña","doi":"10.1099/acmi.0.000709.v3","DOIUrl":"10.1099/acmi.0.000709.v3","url":null,"abstract":"<p><p>We performed genome sequencing and comparative analysis of <i>Pantoea ananatis</i> strains isolated from corn leaves expressing typical bacterial leaf streak (BLS) and maize white spot (MWS) symptoms to confirm bacterial identity and to understand the relationship among these strains and <i>P. ananatis</i> strains isolated from different plant hosts in Brazil. In pathogenicity tests, strains 4.2 and 13.3 isolated from symptomatic BLS leaves were non-pathogenic on corn. In contrast, strain B13 isolated from MWS-diseased leaf tissue caused symptoms typical of MWS. Our comparative analysis revealed that all three strains are very genetically similar. The G+C (%) content of strains 4.2 and 13.3 was 53.5%, while the B13 content was 53.7%. Average nucleotide identity (ANI) analysis showed that strains B13 and 13.3, B13 and 4.2, and 4.2 and 13.3 shared ANIs of 99.17%, 99.15% and 99.99%, respectively. Strains 13.3, B13, and 4.2 shared ~99% ANI with <i>P. ananatis</i> type strain LMG 2665. To the best of our knowledge, these are the first genome sequences of <i>P. ananatis</i> strains isolated from corn in Brazil.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11829076/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-02-14eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000889.v5
Immanuella Owusu-Ansa, Manjeera Ramadas, Nikhitha Jacob, Femi E Ayeni
{"title":"Campylobacter fetus subsp. fetus: an unforeseen cause of abortion in regional Australia.","authors":"Immanuella Owusu-Ansa, Manjeera Ramadas, Nikhitha Jacob, Femi E Ayeni","doi":"10.1099/acmi.0.000889.v5","DOIUrl":"10.1099/acmi.0.000889.v5","url":null,"abstract":"<p><p><i>Campylobacter fetus (C. fetus)</i> subsp. <i>fetus,</i> a Gram-negative bacterium, is an established cause of abortion and infertility in cattle, sheep and goats. Human infections have been rarely reported. In contrast to TORCH infections, this <i>Campylobacter</i> species is hardly recognized as a cause of abortion in humans. Since 1947 after the first case report in France, there have been only 11 reported cases of pregnant women worldwide and no published reports in Australia, pregnant or otherwise. The case in this study was compared to the first reported infection of <i>C. fetus</i> in 1947 to raise awareness and educate doctors and midwives, subsequently impacting prenatal and antenatal counselling in these regions. A Venn diagram was constructed to highlight the similarities between this and the index case. The similarities found included the clinical state of the patient post-abortion and the all-important history of exposure to farm animals that suffered recent deaths on the farms of both patients. Some of the differences included the time of onset of symptoms to the time of abortion, the choice of antibiotics by both treating teams and the presentation of sepsis, suggesting the importance of <i>C. fetus</i> subsp. <i>fetus</i> as a perinatal infection.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11829075/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-02-14eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000858.v3
Nazmul Hasan Muzahid, Aarthi Ramesh, Tan Hock Siew, Md Zobaer Hasan, Kumaran Narayanan, Sadequr Rahman
{"title":"Comparison of the virulence of community- and hospital- isolated Acinetobacter baumannii in HeLa cell line and insect model, Galleria mellonella.","authors":"Nazmul Hasan Muzahid, Aarthi Ramesh, Tan Hock Siew, Md Zobaer Hasan, Kumaran Narayanan, Sadequr Rahman","doi":"10.1099/acmi.0.000858.v3","DOIUrl":"10.1099/acmi.0.000858.v3","url":null,"abstract":"<p><p><i>Acinetobacter baumannii</i> is an important nosocomial pathogen causing high infections and morbidity among affected individuals, and most studies focus on nosocomial strains. However, <i>A. baumannii</i> can also be isolated from healthy community individuals. This study compared the pathogenicity of hospital and community <i>A. baumannii</i> isolates using <i>Galleria mellonella</i> and human cell cultures. The insect model, <i>G. mellonella</i>, and <i>in vitro</i> HeLa cell line were used with ten <i>A. baumannii</i> isolates (six community and four hospital isolates from Segamat, Malaysia). <i>G. mellonella</i> killing assays and HeLa cell adherence, invasion and cytotoxicity assays were performed to investigate the virulence and invasion potential of the isolates. Out of the ten isolates investigated, three community and two hospital isolates were found to be highly virulent in the <i>G. mellonella</i> infection model, killing 100% of larvae within 96 h. These strains were also found to be invasive and have significant cytotoxicity in HeLa cells. Our study revealed that community- and hospital-isolated <i>A. baumannii</i> could be equally virulent judged by both model systems. Undoubtedly, besides hospital settings, the presence of highly virulent <i>A. baumannii</i> in community reservoirs poses a significant public health risk and requires additional investigation.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11829074/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-02-13eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000884.v3
Melanie R Kridler, Amanda Howe, Jimaree A Legins, Christina Guerrero, Ryan P Bartelme, Bridget Taylor, Paul Carini
{"title":"High-quality PacBio draft genome sequences of 17 free-living Bradyrhizobium and four related Nitrobacteraceae strains isolated from arid soils in the Santa Catalina Mountains of Southern Arizona.","authors":"Melanie R Kridler, Amanda Howe, Jimaree A Legins, Christina Guerrero, Ryan P Bartelme, Bridget Taylor, Paul Carini","doi":"10.1099/acmi.0.000884.v3","DOIUrl":"10.1099/acmi.0.000884.v3","url":null,"abstract":"<p><p>Non-symbiotic <i>Bradyrhizobium</i> are among the most abundant and ubiquitous microbes in bulk soils globally. Despite this, most available genomic resources for <i>Bradyrhizobium</i> are derived from plant-associated strains. We present high-quality draft genomes for 17 <i>Bradyrhizobium</i> and four <i>Nitrobacteraceae</i> cultures isolated from bulk semiarid soils in Arizona, USA. The genome sizes range from 5.99 to 10.4 Mbp. Phylogenomic analysis of the 21 genomes indicates they fall into four clades. Two of the clades are nested within the <i>Bradyrhizobium</i> genus. The other two clades were associated with <i>Nitrobacteraceae</i> outgroups basal to <i>Bradyrhizobium</i>. All genomes lack genes coding for molybdenum or vanadium nitrogenases, and <i>nod</i> genes that code for proteins involved in nodulation, suggesting these isolates are free-living, non-symbiotic and do not fix dinitrogen gas. These genomes offer new resources for investigating free-living <i>Bradyrhizobium</i> lineages.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11825986/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-02-13eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000900.v3
Michael J Dillon, James Edwards, Alexandra Hughes, Holly N Stephenson
{"title":"Beyond lectures: leveraging competition, peer discussion and real-world scenarios in a digital card game to enhance learning of microbiology and immunology concepts.","authors":"Michael J Dillon, James Edwards, Alexandra Hughes, Holly N Stephenson","doi":"10.1099/acmi.0.000900.v3","DOIUrl":"10.1099/acmi.0.000900.v3","url":null,"abstract":"<p><p>Teaching the complex interactions between hosts and pathogens is a fundamental yet educationally challenging aspect of life science and healthcare education. The intricate mechanisms of the immune system can pose significant barriers to students' understanding of infectious disease diagnosis and treatment. To address this, we used a web-based digital whiteboard platform to design a card-based competitive game called Micro-Immune Battles, aimed at more actively engaging students with microbiology and immunology to better develop their knowledge and underlying concepts. The game facilitates learning through a series of infectious disease scenarios, providing student teams with 'immune system response cards' that represent various immune elements. Working in teams, learners must construct sequential card cascades that correctly correspond to the specified pathogen in the scenario. This reinforces the temporal progression of immune responses whilst encouraging the application of theoretical knowledge to practical cases. Scoring is determined by the accuracy and speed of card placements, incentivizing rapid yet correct synthesis of knowledge. Points are deducted for incorrect placements, introducing an element of calculated risk-taking and critical reasoning. Analysis showed statistically significant improvements in microbiology and immunology knowledge after playing the game.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11825987/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-01-30eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000832.v4
Alison Pagalilauan, Christina Pavloudi, Santiago Meneses Ospina, Adam Smith, Jimmy H Saw
{"title":"Interaction with refuse piles is associated with co-occurrence of core gut microbiota in workers of the ant Aphaenogaster picea.","authors":"Alison Pagalilauan, Christina Pavloudi, Santiago Meneses Ospina, Adam Smith, Jimmy H Saw","doi":"10.1099/acmi.0.000832.v4","DOIUrl":"10.1099/acmi.0.000832.v4","url":null,"abstract":"<p><p>Comparing the diversity of gut microbiota between and within social insect colonies can illustrate interactions between bacterial community composition and host behaviour. In many eusocial insect species, different workers exhibit different task behaviours. Evidence of compositional differences between core microbiota in different worker types could suggest a microbial association with the division of labour among workers. Here, we present the core microbiota of <i>Aphaenogaster picea</i> ant workers with different task behaviours. The genus <i>Aphaenogaster</i> is abundant worldwide, yet the associated microbiota of this group is unstudied. Bacterial communities from <i>Aphaenogaster picea</i> gut samples in this study consist of 19 phyla, dominated by Proteobacteria, Cyanobacteria and Firmicutes. Analysis of 16S rRNA gene sequences reveals distinct similarity clustering of <i>Aphaenogaster picea</i> gut bacterial communities in workers that have more interactions with the refuse piles. Though gut bacterial communities of nurse and foraging ants are similar in overall composition and structure, the worker groups differ in relative abundances of dominant taxa. Gut bacterial communities from ants that have more interactions with refuse piles are dominated by amplicon sequence variants associated with Entomoplasmataceae. Interaction with faecal matter via refuse piles seems to have the greatest impact on microbial taxa distribution, and this effect appears to be independent of worker type. This is the first report surveying the gut microbiome community composition of <i>Aphaenogaster</i> ants.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11781628/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143070096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-01-29eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000640.v5
Ravinder Kaur, Deepti Rawat, Ashish William, Pradeep Kumar Singh, Neelam S S Kandir, Akanksha Sharma
{"title":"Fungal positivity seen in tertiary care hospital during COVID-19 pandemic.","authors":"Ravinder Kaur, Deepti Rawat, Ashish William, Pradeep Kumar Singh, Neelam S S Kandir, Akanksha Sharma","doi":"10.1099/acmi.0.000640.v5","DOIUrl":"10.1099/acmi.0.000640.v5","url":null,"abstract":"<p><p>Coronavirus disease 2019 (COVID-19) pandemic has been prevailing for more than a year, associated with an increased number of opportunistic invasive fungal infections in patients who have been critically ill or immunocompromised. In this retrospective study, details of various clinical specimens received from suspected patients of fungal infections were studied. Fungal cultures were positive in 64% (51 out of 79) of COVID-19-positive patients and 43% (163 out of 381) of COVID-19-negative patients during the second wave of COVID-19 in 2021. Among COVID-19-infected patients, the most commonly isolated fungi were <i>Candida</i> spp. (63%), followed by <i>Aspergillus</i> spp. (15%) and <i>Mucor</i> spp. (6%). The majority of samples that tested positive in COVID-19-infected patients were urine (17% from COVID-19-positive and 83% from COVID-19-negative patients), followed by serum (tested for <i>Aspergillus</i> galactomannan). <i>Candida</i> isolation was observed in 27% (21/79) of urine samples and 15% (12/79) of respiratory samples [bronchoalveolar lavage (BAL), tracheal aspirate, and sputum] from COVID-19-positive patients. <i>Rhizopus arrhizus</i> and <i>Rhizopus homothallicus</i> were isolated from nasal and tissue samples in 6% of COVID-19-positive patients. There was an overall increase in fungal co-isolations during the COVID-19 pandemic (64% in COVID-19-positive and 43% in COVID-19-negative patients), which is a matter of great concern. The correlation of clinical symptomatology and laboratory isolation is important for the diagnosis and effective management of these patients.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11777003/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143070148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Peribacillus simplex and Klebsiella pneumoniae responsible for pyonephrosis with secondary psoas abscess: a case report.","authors":"Zakaria Malihy, Tilila Abassor, Yassine Ben Lahlou, Elmostafa Benaissa, Mariama Chadli","doi":"10.1099/acmi.0.000911.v3","DOIUrl":"10.1099/acmi.0.000911.v3","url":null,"abstract":"<p><p>Bacterial urinary tract infections (UTIs) are common, ranging from benign cystitis to complicated pyelonephritis, which can lead to severe complications such as pyonephrosis and sepsis. Pyonephrosis, characterized by the presence of pus in the renal cavities, often requires urgent urological intervention. We report a unique case of pyonephrosis with a psoas abscess caused by <i>Klebsiella pneumoniae</i> and <i>Peribacillus simplex</i> in a 64-year-old diabetic female patient. This is the first case of pyonephrosis caused by <i>P. simplex</i>. The patient presented with acute right lumbar pain, fever and altered consciousness. Imaging revealed severe right hydronephrosis, pyonephrosis and a perirenal phlegmon infiltrating the psoas with abscesses. Surgical drainage and nephrectomy were performed. Microbiological and proteomic analyses identified <i>K. pneumoniae</i> and <i>P. simplex</i>. This case highlights the importance of considering environmental bacteria like <i>P. simplex</i> in severe infections and ensuring rigorous protocols to avoid contamination. Successful management of pyonephrosis relies on prompt surgical drainage and appropriate antibiotic therapy based on culture results.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11729731/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142985956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Access microbiologyPub Date : 2025-01-13eCollection Date: 2025-01-01DOI: 10.1099/acmi.0.000791.v3
Michael Asamoah-Boaheng, David M Goldfarb, Iryna Kayda, Justin Yap, Tracy Kirkham, Mohammad Ehsanul Karim, Paul Demers, Jeffrey M Copp, Brian Grunau
{"title":"Immunogenicity of bivalent versus monovalent mRNA booster vaccination among adult paramedics in Canada who had received three prior mRNA wild-type doses.","authors":"Michael Asamoah-Boaheng, David M Goldfarb, Iryna Kayda, Justin Yap, Tracy Kirkham, Mohammad Ehsanul Karim, Paul Demers, Jeffrey M Copp, Brian Grunau","doi":"10.1099/acmi.0.000791.v3","DOIUrl":"10.1099/acmi.0.000791.v3","url":null,"abstract":"<p><p><b>Introduction.</b> Comparative immunogenicity from different mRNA booster vaccines (directed at WT, BA.1 or BA.4/5 antigens) remains unclear. <b>Methods.</b> We included blood samples from adult paramedics who received three mRNA WT-directed vaccines plus a fourth dose of the following: (1) WT monovalent, (2) Moderna BA.1-WT bivalent or (3) Pfizer BA.4/5 WT bivalent vaccine. The primary outcome was angiotensin-converting enzyme 2 (ACE2) inhibition to BA.4/5 antigen. We used optimal pair matching (using age, sex-at-birth, preceding SARS-CoV-2 infection and fourth vaccine-to-blood collection interval) to create balanced groups to individually compare each vaccine type to each other vaccine (overall, within subgroups defined by SARS-CoV-2 infection and after combining BA.1 and BA.4/5 cases). We compared outcomes with the Wilcoxon matched-pairs signed rank test. <b>Results.</b> Overall, 158 paramedics (mean age 45 years) were included. ACE2 inhibition was higher for BA.1 compared to WT (<i>P</i>=0.002); however, no difference was detected between BA.4/5 vs. WT or BA.1 vs. BA.4/5. Among cases with preceding SARS-CoV-2, there were no detected between-group differences. Among cases without preceding SARS-CoV-2, the only detected difference was BA.1>WT (<i>P</i>=0.003). BA.1 and BA.4/5 cases combined had higher ACE2 inhibition than WT (<i>P</i>=0.003). <b>Conclusion.</b> Omicron-directed vaccines appear to improve Omicron-specific immunogenicity; however, this appears limited to SARS-CoV-2-naive individuals.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11728694/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142980914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}