Microorganisms

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12 pages, 1252 KiB

Open AccessArticle

Clostridioides difficile Infections in Children: What Is the Optimal Laboratory Diagnostic Method?

by Mohammed Suleiman, Patrick Tang, Omar Imam, Princess Morales, Diyna Altrmanini, Jill C. Roberts and Andrés Pérez-López

Microorganisms 2024, 12(9), 1785; https://doi.org/10.3390/microorganisms12091785 - 28 Aug 2024

Cited by 1 | Viewed by 977

Abstract

The diagnosis of Clostridioides difficile infection (CDI) in the pediatric population is complicated by the high prevalence of asymptomatic colonization, particularly in infants. Many laboratory diagnostic methods are available, but there continues to be controversy over the optimal laboratory testing approach to diagnose [...] Read more.

The diagnosis of Clostridioides difficile infection (CDI) in the pediatric population is complicated by the high prevalence of asymptomatic colonization, particularly in infants. Many laboratory diagnostic methods are available, but there continues to be controversy over the optimal laboratory testing approach to diagnose CDI in children. We evaluated commonly used C. difficile diagnostic commercial tests in our pediatric hospital population at Sidra Medicine in Doha, Qatar. Between June and December 2023, 374 consecutive stool samples from pediatric patients aged 0–18 years old were tested using: Techlab C. diff Quik Chek Complete, Cepheid GeneXpert C. difficile, QIAstat-Dx Gastrointestinal Panel, and culture using CHROMagar C. difficile. The results of these tests as standalone methods or in four different testing algorithms were compared to a composite reference method on the basis of turnaround time, ease of use, cost, and performance characteristics including specificity, sensitivity, negative predictive value, and positive predictive value. Our study showed variability in test performance of the different available assays in diagnosing CDI. In our population, a testing algorithm starting with Cepheid GeneXpert C. difficile PCR assay or QIAstat-Dx Gastrointestinal panel as a screening test followed by toxin immunoassay for positive samples using the Techlab C. diff Quik Chek Complete kit showed the best performance (100% specificity and 100% positive predictive value) when combined with clinical review of the patient to assess risk factors for CDI, clinical presentation, and alternative causes of diarrhea. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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Figure 1
Sensitivity vs. Specificity comparison for all methods & algorithms in 2–18 years old. CAC, CHROMagar C. difficile; CDQ, C. diff Quik Chek Complete kit immunoassay; GDH, Glutamate dehydrogenase; QGP, QIAstat-Dx Gastrointestinal Panel 2 PCR test; XCD, Xpert C. difficile PCR test. Algorithm 1, CDQ arbitrated by XCD; Algorithm 2, CDQ arbitrated by QIAstat-Dx Multiplex PCR; Algorithm 3, XCD followed by toxin A/B from the CDQ kit; Algorithm 4, QGP followed by toxin A/B from the CDQ kit. Full article ">Figure 2
Sensitivity vs. Specificity comparison for all methods & algorithms in <2 years old. CAC, CHROMagar C. difficile; CDQ, C. diff Quik Chek Complete kit immunoassay; GDH, Glutamate dehydrogenase; QGP, QIAstat-Dx Gastrointestinal Panel 2 PCR test; XCD, Xpert C. difficile PCR test. Algorithm 2, CDQ arbitrated by QIAstat-Dx Multiplex PCR. Full article ">Figure 3
PPV vs. NPV comparison for all methods & algorithms in 2–18 years old. CAC, CHROMagar C. difficile; CDQ, C. diff Quik Chek Complete kit immunoassay; GDH, Glutamate dehydrogenase; NPV, Negative predictive value; PPV, Positive predictive value; QGP, QIAstat-Dx Gastrointestinal Panel 2 PCR test; XCD, Xpert C. difficile PCR test. Algorithm 1, CDQ arbitrated by XCD; Algorithm 2, CDQ arbitrated by QIAstat-Dx Multiplex PCR; Algorithm 3, XCD followed by toxin A/B from the CDQ kit; Algorithm 4, QGP followed by toxin A/B from the CDQ kit. Full article ">Figure 4
PPV vs. NPV comparison for all methods & algorithms in <2 years old. CAC, CHROMagar C. difficile; CDQ, C. diff Quik Chek Complete kit immunoassay; GDH, Glutamate dehydrogenase; NPV, Negative predictive value; PPV, Positive predictive value; QGP, QIAstat-Dx Gastrointestinal Panel 2 PCR test; XCD, Xpert C. difficile PCR test. Algorithm 2, CDQ arbitrated by QIAstat-Dx Multiplex PCR; Algorithm 3, XCD followed by toxin A/B from the CDQ kit; Algorithm 4, QGP followed by toxin A/B from the CDQ kit. Full article ">

7 pages, 696 KiB

Open AccessCommunication

Evaluation of Direct Antimicrobial Susceptibility Testing of Gram-Negative Bacilli and Staphylococcus aureus from Positive Pediatric Blood Culture Bottles Using BD Phoenix M50

by Princess Morales, Patrick Tang, Elaine Mariano, Arun Gopalan, Nisha Aji, Andrés Pérez-López and Mohammed Suleiman

Microorganisms 2024, 12(8), 1704; https://doi.org/10.3390/microorganisms12081704 - 18 Aug 2024

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Abstract

Bloodstream infections (BSIs) are life-threatening infections for which a timely initiation of appropriate antimicrobial therapy is critical. Antibiotic susceptibility testing (AST) directly performed on positive blood culture broths can help initiate targeted antibiotic therapy sooner than the standard AST performed on colonies isolated [...] Read more.

Bloodstream infections (BSIs) are life-threatening infections for which a timely initiation of appropriate antimicrobial therapy is critical. Antibiotic susceptibility testing (AST) directly performed on positive blood culture broths can help initiate targeted antibiotic therapy sooner than the standard AST performed on colonies isolated on solid media after overnight incubation. Faster antimicrobial susceptibility testing (AST) results can improve clinical outcomes, and reduce broad-spectrum antimicrobial consumption and healthcare-associated costs in sepsis. In this study, we evaluated the accuracy of a direct AST inoculation method on the BD Phoenix M50 system using serum separator tubes to harvest bacteria from positive pediatric blood culture bottles. Direct AST was performed on 132 monomicrobial pediatric blood culture bottles that were positive for Enterobacterales (65; 49.2%), Staphylococcus aureus (46; 34.8%), and non-fermenting Gram-negative bacilli (21; 16%). Overall, the categorical and essential agreements between the direct method and standard method were 99.6% and 99.8%, respectively. Very major, major, and minor error rates were 0.1%, 0.09%, and 0.20% respectively. Direct AST performed on pediatric blood culture bottles using BD Phoenix M50 can quickly provide accurate susceptibility information to guide antimicrobial therapy in patients with BSI. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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15 pages, 2093 KiB

Open AccessArticle

Streptococcus thermophilus iHA318 Improves Dry Eye Symptoms by Mitigating Ocular Surface Damage in a Mouse Model

by Yu-Wei Chang, Yen-Ling Sun, Evelyn Chu, Yi-Yun Hung, Wei-Chieh Liao, Su-Min Tsai, Tsung-Han Lu, Pin-Chao Huang, Chin-Hsiu Yu, Shao-Yu Lee, Han-Hsin Chang and David Pei-Cheng Lin

Microorganisms 2024, 12(7), 1306; https://doi.org/10.3390/microorganisms12071306 - 27 Jun 2024

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Abstract

Dry eye is a complicated ocular surface disease that causes discomfort, visual disturbance, and frequently observed ocular surface damage. Emerging hypotheses suggest probiotics may help relieve dry eye symptoms by modulating inflammation and oxidative stress. This study aimed to investigate the therapeutic effects [...] Read more.

Dry eye is a complicated ocular surface disease that causes discomfort, visual disturbance, and frequently observed ocular surface damage. Emerging hypotheses suggest probiotics may help relieve dry eye symptoms by modulating inflammation and oxidative stress. This study aimed to investigate the therapeutic effects of Streptococcus thermophilus iHA318 probiotics on dry eye using in vitro assays and an in vivo murine model of ultraviolet B (UVB) radiation-induced dry eye. In vitro analyses revealed that S. thermophilus iHA318^® exhibited antioxidant activity and anti-inflammatory effects by inhibiting reactive oxygen species production and suppressing inflammatory cytokines. For the in vivo study, female ICR mice were assigned to normal control, UVB-induced dry eye, and UVB+iHA318 treatment groups. UVB exposure significantly decreased tear volume and tear film breakup time (TBUT) compared to normal controls. Supplementation with S. thermophilus iHA318^® via oral gavage markedly improved tear production and TBUT on day 7 post-UVB exposure. Ocular surface photography demonstrated improved gradings of corneal opacity, smoothness, and lissamine green staining in the iHA318 group versus the UVB group. Topographical analysis further revealed improvement in the UVB-induced corneal irregularities by iHA318 treatment. Collectively, these results indicate that S. thermophilus iHA318 exerts a protective effect against dry eye symptoms by mitigating oxidative stress and inflammation, thereby preserving tear film stability and ocular surface integrity. This probiotic strain represents a promising therapeutic approach for managing dry eye syndrome. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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Figure 1
Morphological and functional characterization of S. thermophilus strains. (A) Microscopic images of S. thermophilus BCRC 14017 (left) and iHA318 (right) strains at 1000× magnification. Black arrows indicate BCRC 14017 strain, while red arrows point to iHA318 strain. Scale bar: 10 μm. (B) Sialic acid production by S. thermophilus strains BCRC14017, ST002, and iHA318. (C) Hyaluronic acid production by S. thermophilus strains BCRC14017, ST002, and iHA318. Data in (B,C) are presented as mean ± SEM. **** indicates a p-value < 0.0001. Full article ">Figure 2
Protective effects of S. thermophilus iHA318 on human retinal pigment epithelial cells (ARPE-19) and macrophages (RAW 264.7). (A) Cell viability of ARPE-19 cells under osmotic stress induced by NaCl exposure, with or without iHA318 treatment. (B) Intracellular reactive oxygen species (ROS) production in ARPE-19 cells with or without iHA318 treatment. (C) Cell viability of RAW 264.7 macrophages exposed to oxidant AAPH, with or without iHA318 treatment. (D) Nitric oxide (NO) production by RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS), with or without iHA318 treatment. Data are presented as mean ± SEM. **** indicates a p-value < 0.0001. Full article ">Figure 3
Effects of oral administration of S. thermophilus iHA318 on tear volume and tear film stability in a mouse model of dry eye disease. (A) Graphical illustration of the 11-day experimental timeline showing the periods of UVB exposure (days 1–7), oral gavage treatment administration (days −2 to 7), and evaluation time points for tear volume, tear film break-up time (TBUT), and ocular surface parameters. Blue triangles indicate tear volume and TBUT test days, while red triangles represent ocular surface photography days. (B) Tear volume measurements in mice from the blank, damage, low-dose iHA318, high-dose iHA318, and artificial tear groups on days 0, 4, and 7. (C) TBUT measurements in mice from the blank, damage, low-dose iHA318, high-dose iHA318, and artificial tear groups on days 0, 4, and 7. Data are presented as mean ± SEM. ns indicates no significant difference, * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001. Full article ">Figure 4
Effects of S. thermophilus iHA318 on corneal opacity in a mouse model of dry eye disease. (A) Representative images of corneal opacity in mice from the blank, damage, low-dose, high-dose, and artificial tear (AFT) groups on day 8. (B) Quantification of corneal opacity scores in mice from the blank, damage, low-dose iHA318, high-dose iHA318, and AFT groups on day 8. The opacity scores were determined by two observers who were blinded to the independent experiment (n = 5). Data are presented as mean ± SEM. ns indicates no significant difference; * indicates p < 0.05, and *** indicates p < 0.001. Full article ">Figure 5
Effects of S. thermophilus iHA318 on corneal smoothness in a mouse model of dry eye disease. (A) Representative images of corneal smoothness in mice from the blank, damaged, low-dose iHA318, high-dose iHA318, and artificial tear (AFT) groups on day 8. (B) Quantification of corneal smoothness scores in mice from the blank, damage, low-dose, high-dose, and AFT groups on day 8. The smoothness scores were determined by two observers who were blinded to the independent experiment (n = 5). Data are presented as mean ± SEM. ns indicates no significant difference; * indicates p < 0.05, and **** indicates p < 0.0001. Full article ">Figure 6
Effects of S. thermophilus iHA318 on corneal topography in a mouse model of dry eye disease. (A) Representative images of corneal topography assessment in mice from the blank, damage, low-dose iHA318, high-dose iHA318, and AFT groups on day 8. (B) Quantification of corneal topography scores in mice from the blank, damage, low-dose iHA318, high-dose iHA318, and AFT groups on day 8. The topography scores were determined by two observers who were blinded to the independent experiment (n = 5). Data are presented as mean ± SEM. ns indicates no significant difference; * indicates p < 0.05, and **** indicates p < 0.0001. Full article ">Figure 7
Lissamine green staining evaluation of S. thermophilus iHA318 in a dry eye mouse model. (A) Representative images of lissamine green staining on the ocular surface under different treatment conditions on day 8: blank, damage, low-dose iHA318, high-dose iHA318, and AFT. The upper row shows the original images, while the lower row shows the images with enhanced color temperature to better visualize the staining patterns. (B) Quantification of lissamine green staining scores by two blinded observers based on the independent experiments (n = 5). Data are presented as mean ± SEM. ns indicates no significant difference. * indicates p < 0.05. Full article ">

8 pages, 1584 KiB

Open AccessCommunication

Use of PCR Cycle Threshold and Clinical Interventions to Aid in the Management of Pediatric Clostridioides difficile Patients

by Mohammed Suleiman, Patrick Tang, Omar Imam, Princess Morales, Diyna Altrmanini, Kelli L. Barr, Jill C. Roberts and Andrés Pérez-López

Microorganisms 2024, 12(6), 1181; https://doi.org/10.3390/microorganisms12061181 - 11 Jun 2024

Viewed by 978

Abstract

Better diagnostic tools are needed to improve the diagnosis of Clostridioides difficile infections (CDI) and reduce the overtreatment of colonized children. In this study, we evaluated two polymerase chain reaction (PCR) assays (Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx) [...] Read more.

Better diagnostic tools are needed to improve the diagnosis of Clostridioides difficile infections (CDI) and reduce the overtreatment of colonized children. In this study, we evaluated two polymerase chain reaction (PCR) assays (Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx) as a standalone method in combination with the PCR cycle threshold (Ct) value in positive samples to predict the presence of free toxins. We also evaluated the clinical impact of reporting toxin production results and provided comments alongside the PCR results in our pediatric population. PCR-positive stool samples from pediatric patients (aged 2 to 18 years old) were included in our study and tested for the presence of toxins A and B using the C. difficile Quik Chek Complete kit. For the clinical intervention, the CDI treatment rates 6 months pre- and post-intervention were compared. The use of PCR Ct value showed excellent sensitivity (100%) at a Ct value cutoff of 26.1 and 27.2 using the Cepheid GeneXpert C. difficile and the Gastroenteritis PCR Panel by QIAstat-Dx, respectively, while the toxin test showed inferior sensitivity of 64% in the PCR-positive samples. In addition, CDI treatment rates were decreased by 23% post-intervention. The results of our study suggest that nucleic acid amplification test (NAAT) assays supplemented by the use of PCR Ct value for positive samples can be used as standalone tests to differentiate CDI from colonization. Furthermore, the reporting of toxin production along with the PCR results can help reduce the unnecessary treatment of colonized children. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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13 pages, 245 KiB

Open AccessArticle

Nocardiosis in Solid Organ Transplant Recipients: 10-Year Single Center Experience and Review of Literature

by Julia Bini Viotti, Jacques Simkins, John M. Reynolds, Gaetano Ciancio, Giselle Guerra, Lilian Abbo and Shweta Anjan

Microorganisms 2024, 12(6), 1156; https://doi.org/10.3390/microorganisms12061156 - 6 Jun 2024

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Abstract

Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim–sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may [...] Read more.

Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim–sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may have a role in preventing early infections. This is a single-center retrospective cohort study of nocardiosis in adult SOTRs at a large transplant center between January 2012 and June 2022, with comprehensive review of literature. Out of 6179 consecutive cases, 13 (0.2%) were diagnosed with nocardiosis. The patients were predominantly male (76.9%) and kidney transplant recipients (62%). Infection was diagnosed at median of 8.8 months (range, 3.7–98) after transplant. Patients were followed for a median of 457 days (range 8–3367). Overall mortality within one year after diagnosis was 46% (6/13), of which 17% (1/6) of deaths was attributable to Nocardia infection. No recurrence was reported. Nocardia infections were noted in a small proportion of our SOTRs and carried significant morbidity and mortality. TMP-SMX prophylaxis may be protective in some cases given low incidence of cases. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

6 pages, 189 KiB

Open AccessCommunication

Antibiotic Resistance Profiles in Eye Infections: A Local Concern with a Retrospective Focus on a Large Hospital in Northern Italy

by Lorenzo Drago, Vincenzo Minasi, Andrea Lembo, Angela Uslenghi, Sofia Benedetti, Matteo Covi, Paolo Nucci and Loredana Deflorio

Microorganisms 2024, 12(5), 984; https://doi.org/10.3390/microorganisms12050984 - 14 May 2024

Cited by 1 | Viewed by 1297

Abstract

The emergence of antibiotic resistance poses a significant threat to public health worldwide, affecting various medical fields, including ophthalmology. Eye infections, ranging from conjunctivitis to more severe conditions like keratitis, are commonly treated with antibiotics. However, the misuse and overuse of these drugs [...] Read more.

The emergence of antibiotic resistance poses a significant threat to public health worldwide, affecting various medical fields, including ophthalmology. Eye infections, ranging from conjunctivitis to more severe conditions like keratitis, are commonly treated with antibiotics. However, the misuse and overuse of these drugs have led to the development of resistant strains of bacteria, allowing traditional treatments ineffective. This paper aims to examine the current situation of antibiotic resistance in eye infections globally, with a specific focus on a large group of hospitals located in Milan (Italy) with considerable experience in cataract and cornea surgery as well as in retinopathy. The results of the study show the prevalence of Gram-positives in the tested samples and a low resistance of fluoroquinolones and glycopeptides. The results also highlight the need to implement sample collection methods for ocular infections, as the quantity of positive samples is rather low compared to the total number of samples. In conclusion, the study, although with limited data, shows that resistance to aminoglycosides and cephalosporins is a situation to be monitored. These data also show the critical need to improve and guide the biological sample collection modalities in order to make the diagnosis more reliable. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

17 pages, 937 KiB

Open AccessArticle

Prospective Longitudinal Study of Dynamics of Human Papillomavirus 6 and 11 Infection in Anogenital Hairs and Eyebrows of Male Patients with Anogenital Warts and Age-Matched Controls

by Vesna Tlaker, Lea Hošnjak, Mateja Kolenc, Tomaž Mark Zorec, Boštjan Luzar, Marko Potočnik, Jovan Miljković, Katja Seme and Mario Poljak

Microorganisms 2024, 12(3), 466; https://doi.org/10.3390/microorganisms12030466 - 25 Feb 2024

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Abstract

To better understand the natural history of anogenital warts (AGWs) and the dynamics of HPV6/11 infection in regional hairs, 32 newly diagnosed male patients with AGWs and 32 age-matched healthy controls were closely followed. During enrollment and six follow-up visits (every 2.6 months), [...] Read more.

To better understand the natural history of anogenital warts (AGWs) and the dynamics of HPV6/11 infection in regional hairs, 32 newly diagnosed male patients with AGWs and 32 age-matched healthy controls were closely followed. During enrollment and six follow-up visits (every 2.6 months), 43 AGW tissues and 1232 anogenital and eyebrow hair samples were collected. This is the closest longitudinal monitoring of AGW patients to date. Patients were treated according to standards of care. The HPV6/11 prevalence was 19.9% in the patients’ hair samples (HPV6 B1 in 53.1%) and 0% in the controls. The highest HPV6/11 prevalence was found in pubic hairs (29.0%) and the lowest in eyebrows (7.1%). The odds of having HPV6/11-positive hairs increased with smoking, shaving the anogenital region, and age. A close association between HPV6/11 presence in hairs and clinically visible AGWs was observed. The proportion of patients with visible AGWs and HPV6/11-positive hairs declined during follow-up with similar trends. No particular HPV6/11 variant was linked with an increased AGW recurrence, but the sublineage HPV6 B1 showed significantly higher clearance from hairs. Despite treatment, 78.1% and 62.5% of the AGW patients experienced one and two or more post-initial AGW episodes, respectively. The patients with HPV6/11-positive hairs or visible AGWs at a preceding visit demonstrated substantially higher odds of presenting with visible AGWs at a subsequent visit. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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Review

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22 pages, 3802 KiB

Open AccessReview

The Role of Bacteria in Central Nervous System Tumors: Opportunities and Challenges

by Rui Zhang, Xueying Li and Si Zhang

Microorganisms 2024, 12(6), 1053; https://doi.org/10.3390/microorganisms12061053 - 23 May 2024

Cited by 1 | Viewed by 1878

Abstract

Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria [...] Read more.

Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria can penetrate the blood–brain barrier (BBB), targeting the hypoxic microenvironment at the core of tumors, thereby eliminating tumors and activating both the innate and adaptive immune responses, rendering them promising therapeutic agents for CNS tumors. In addition, engineered bacteria and derivatives, such as bacterial membrane proteins and bacterial spores, can also be used as good candidate carriers for targeted drug delivery. Moreover, the intestinal flora can regulate CNS tumor metabolism and influence the immune microenvironment through the “gut–brain axis”. Therefore, bacterial anti-tumor therapy, engineered bacterial targeted drug delivery, and intervention of the intestinal flora provide therapeutic modalities for the treatment of CNS tumors. In this paper, we performed a comprehensive review of the mechanisms and therapeutic practices of bacterial therapy for CNS tumors and discussed potential future research directions in this field. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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Graphical abstract
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Photothermal immunotherapy of brain tumors mediated by attenuated bacteria: (a) bacteria form the Trojan Bacterial System by endocytosis of nanoparticles via the ABC transporter; (b) the Trojan Bacterial System crosses the BBB and targets brain tumors, where bacterial lysis triggers an immune response under exogenous near-infrared light irradiation. Reproduced with permission [<a href="#B11-microorganisms-12-01053" class="html-bibr">11</a>]. Copyright 2022, Springer Nature. Abbreviations: SiNP, silicon nanoparticle; GP, glucose polymer; ICG, indocyanine green; Trojan EC, Trojan Escherichia coli 25922; ABC, ATP-binding cassette; Trojan VNP, Trojan Salmonella typhimurium VNP20009; GBM, glioblastoma; BBB, blood–brain barrier; iDC, immature dendritic cell; mDC, mature dendritic cell; NK cells, natural killer cells. Full article ">Figure 2
Bacterial outer membrane protein-mediated targeted drug delivery. Targeting GRP94 using attenuated Escherichia coli DHα5 outer membrane proteins to target penetration of the BBB as well as access to the interior of brain metastases and carry EMB to induce apoptosis in tumor cells. Reproduced with permission [<a href="#B72-microorganisms-12-01053" class="html-bibr">72</a>]. Copyright 2023, Wiley-VCH. Abbreviations: E. coli, Escherichia coli; GRP94, glucose-regulated protein 94; BBB, blood–brain barrier; Omp@EMB, outer membrane protein-coated Embelin; NC core, nanocapsule core; L1CAM, cell adhesion molecule L1. Full article ">Figure 3
Targeted delivery of chemotherapeutic agents mediated by bacterial outer membrane proteins: (a) Neisseria meningitidis outer membrane protein Opca is combined with MnO2-wrapped MTX to form a bionic nanotherapeutic system; (b) The bionic nanosystem crosses the BBB, targets brain tumors, and uses the catalytic effect of MnO2 to alleviate the hypoxic environment inside the tumor and reverse the tumor’s resistance to MTX. Reproduced with permission [<a href="#B38-microorganisms-12-01053" class="html-bibr">38</a>]. Copyright 2022, Wiley-VCH. Abbreviations: MTX, methotrexate; MnO2, manganese dioxide; Opca, outer membrane invasion protein; EDC/NHS, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide; BBB, blood–brain barrier; H2O2, hydrogen peroxide. Full article ">

13 pages, 1570 KiB

Open AccessReview

Bacteria Living in Biofilms in Fluids: Could Chemical Antibiofilm Pretreatment of Culture Represent a Paradigm Shift in Diagnostics?

by Lorenzo Drago, Andrea Fidanza, Alessio Giannetti, Alessio Ciuffoletti, Giandomenico Logroscino and Carlo Luca Romanò

Microorganisms 2024, 12(2), 259; https://doi.org/10.3390/microorganisms12020259 - 26 Jan 2024

Cited by 4 | Viewed by 1850 | Correction

Abstract

Biofilms are multicellular aggregates of bacteria immersed in an extracellular matrix that forms on various surfaces, including biological tissues and artificial surfaces. However, more and more reports point out the fact that even biological fluids and semifluid, such as synovial liquid, blood, urine, [...] Read more.

Biofilms are multicellular aggregates of bacteria immersed in an extracellular matrix that forms on various surfaces, including biological tissues and artificial surfaces. However, more and more reports point out the fact that even biological fluids and semifluid, such as synovial liquid, blood, urine, or mucus and feces, harbor “non-attached” biofilm aggregates of bacteria, which represent a significant phenomenon with critical clinical implications that remain to be fully investigated. In particular, biofilm aggregates in biological fluid samples have been shown to play a relevant role in bacterial count and in the overall accuracy of microbiological diagnosis. In line with these observations, the introduction in the clinical setting of fluid sample pretreatment with an antibiofilm chemical compound called dithiothreitol (DTT), which is able to dislodge microorganisms from their intercellular matrix without killing them, would effectively improve the microbiological yield and increase the sensitivity of cultural examination, compared to the current microbiological techniques. While other ongoing research continues to unveil the complexity of biofilm formation in biological fluids and its impact on infection pathogenesis and diagnosis, we here hypothesize that the routine use of a chemical antibiofilm pretreatment of fluid and semi-solid samples may lead to a paradigm shift in the microbiological approach to the diagnosis of biofilm-related infections and should be further investigated and eventually implemented in the clinical setting. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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Figure 1
Bacteria organized in biofilm in synovial fluid. The co-aggregation of numerous bacteria (green dots) can be seen, as outlined by the red line (adapted from Bidossi et al. [<a href="#B25-microorganisms-12-00259" class="html-bibr">25</a>]). Full article ">Figure 2
(A) The arrows in the figure show coaggregation of bacteria; (B) dithiothreitol (DTT) pretreatment breaks the biofilm structure and frees the bacteria in the planktonic state. The arrows indicate free bacteria cells after DTT antibiobilm usage. Full article ">Figure 3
Schematic representation of the potential ability of a chemical antibiofilm pretreatment with dithiothreitol to increase the bacterial count and cultural examination sensitivity of a fluid sample: (A) Two planktonic bacteria (green disks) in a biological fluid sample together with biofilm-embedded bacteria adhered to a surface (*), and a non-attached biofilm aggregate (**). Cultural examination of this sample will provide two to four colony-forming units (green disks in the agar plate on the right), as each biofilm aggregate, if culturable, will be counted as only one colony-forming unit. (B) Dithiothreitol (red squares) added to the biological fluid breaks biofilm aggregates and frees the microorganisms in a planktonic state; (C) this phenomenon leads to a change in the number of planktonic culturable cells and hence of colony-forming units, which, in this example, will now be up to 10 instead of 4, as each individual cell will be able to generate a distinct colony. Full article ">Figure 3 Cont.
Schematic representation of the potential ability of a chemical antibiofilm pretreatment with dithiothreitol to increase the bacterial count and cultural examination sensitivity of a fluid sample: (A) Two planktonic bacteria (green disks) in a biological fluid sample together with biofilm-embedded bacteria adhered to a surface (*), and a non-attached biofilm aggregate (**). Cultural examination of this sample will provide two to four colony-forming units (green disks in the agar plate on the right), as each biofilm aggregate, if culturable, will be counted as only one colony-forming unit. (B) Dithiothreitol (red squares) added to the biological fluid breaks biofilm aggregates and frees the microorganisms in a planktonic state; (C) this phenomenon leads to a change in the number of planktonic culturable cells and hence of colony-forming units, which, in this example, will now be up to 10 instead of 4, as each individual cell will be able to generate a distinct colony. Full article ">

Other

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1 pages, 173 KiB

Open AccessCorrection

Correction: Drago et al. Bacteria Living in Biofilms in Fluids: Could Chemical Antibiofilm Pretreatment of Culture Represent a Paradigm Shift in Diagnostics? Microorganisms 2024, 12, 259

by Lorenzo Drago, Andrea Fidanza, Alessio Giannetti, Alessio Ciuffoletti, Giandomenico Logroscino and Carlo Luca Romanò

Microorganisms 2024, 12(12), 2577; https://doi.org/10.3390/microorganisms12122577 - 13 Dec 2024

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Abstract

In the original publication [...] Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

6 pages, 655 KiB

Open AccessCase Report

Community-Acquired Solitary Brain Abscesses Caused by Hypervirulent Klebsiella pneumoniae in a Healthy Adult

by Joo-Hee Hwang, Jung Soo Park, Tae Won Bae, Jeong-Hwan Hwang and Jaehyeon Lee

Microorganisms 2024, 12(5), 894; https://doi.org/10.3390/microorganisms12050894 - 29 Apr 2024

Cited by 1 | Viewed by 1262

Abstract

A 42-year-old man was admitted to the emergency room complaining of fever and headache. His cerebrospinal fluid showed a cloudy appearance, and his white blood cell count was elevated at 2460/mm³, with a predominance of neutrophils (81%), and abnormal protein and [...] Read more.

A 42-year-old man was admitted to the emergency room complaining of fever and headache. His cerebrospinal fluid showed a cloudy appearance, and his white blood cell count was elevated at 2460/mm³, with a predominance of neutrophils (81%), and abnormal protein and glucose levels (510.7 mg/dL and 5 mg/dL, respectively). A lobulated lesion with rim enhancement, suggestive of abscess, was detected through magnetic resonance imaging. Klebsiella pneumoniae was detected in nasopharyngeal swab and blood cultures. The capsular serotype of K. pneumoniae was K2 and the sequence type determined by multilocus sequence typing was 23. The hypervirulent phenotype was associated with multiple virulent genes, including rmpA, rmpA2, entB, ybtS, kfu, iucA, iutA, iroB mrkD, allS, peg-344, peg-589, and peg-1631. After six weeks of receiving appropriate antibiotics and exhibiting clinical resolution of the brain abscesses, the patient was discharged. We present the first reported case of a healthy community-dwelling adult with solitary brain abscesses, and no other invasive abscesses, related to hypervirulent K. pneumoniae. Full article

(This article belongs to the Special Issue Advances in Medical Microbiology)

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