Acid-fast bacteria as causative agents of skin and soft tissue infections: case presentations and literature review

Acid-fast bacteria can be implicated in skin and soft tissue infections. Diagnostic identification can be challenging or not feasible by routine laboratory techniques, especially if there is no access to the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) technology. Here, we present two cases of skin and soft tissue infections caused by two different acid-fast bacteria, Nocardia brasiliensis and Mycobacterium marinum. They both grew on Löwenstein–Jensen medium, Sabouraud agar medium and blood agar medium. Both bacteria appeared acid-fast by Ziehl–Neelsen stain and Gram-positive by Gram stain. The identification was performed by MALDI-TOF MS and gene analysis. N. brasiliensis and nontuberculous mycobacterium M. marinum represent rare pathogens that cause severe skin and soft tissue infections. Failure to identify the causative agent and subsequent inappropriate or inadequate treatment may lead to severe complications or even disseminated disease, especially in immunocompromised individuals

Epidemiological markers of pseudomonas aeruginosa

A total of 70 P. aeruginosa strains were isolated during a one year period at the University Hospital of Patras Medical School and typed by various methods. Antimicrobial susceptibility testing distinguished between susceptible and multi-resistant strains revealing a high level (18,5%) of resistance. Serotyping by International Antigenic Typing system (IATS) antisera was succesfull. A specific Ο serotype was detected in all tested strains. Non typable or polyagluttinating strains were not observed. The predominant serotype was 0:12 followed by 0:6, 0:3, 0:11 and 0:7. The majority of multiresistant strains belonged to 0:12 serotype. Strains of identical serotype were not further differentiated by lipopolysaccharide and whole cell protein electrophoretic profile. Plasmid profiles coupled with restriction endonuclease analysis revealed a common pattern in all tested strains. A common plasmid of 23kb size was present in all isolates examined, propably being a cryptic plasmid. Our results suggest that all typing systems for P. aeruginosa have merits and limitations and serotyping by IATS antisera remain the most reproducible and simple method. The combination of serotyping and a molecular biology method is the most succesfull typing system.Στο Πανεπιστημιακό Μικροβιολογικό Εργαστήριο του Γενικού Νοσοκομείου Πατρών απομονώθηκαν στη διάρκεια ενός έτους 70 στελέχη P. aeruginosa τα οποία τυποποιήθηκαν με καθιερωμένες και μη μεθόδους. Το αντιβιόγραμμα διεχώρισε αδρά σε ευαίσθητα και πολυανθεκτικά στελέχη αποκαλύπτοντας υψηλό ποσοστό πολυανθεκτικών στελεχών (18,5%). Η χρήση αντιορών του συστήματος IATS κατέταξε όλα τα στελέχη σε συγκεκριμένο ορότυπο χωρίς να παρατηρηθούν πολυσυγκολλώμενα ή μη τυποποιούμενα στελέχη. Τα πολυανθεκτικά στελέχη ανήκαν κατά πλειοψηφία στον ορότυπο 12. Επικρατούντες ορότυποι στο σύνολο των στελεχών ήσαν κατά σειρά συχνότητος 12, 6, 3, 11 και 7. Η ηλεκτροφόρηση λιποπολυσακχαριτών και ολικών πρωτεϊνών με αποδιατακτικούς παράγοντες (SDS-PAGE) δεν συνέβαλε στην ομαδοποίηση στελεχών του ιδίου οροτύπου λόγω ποικιλίας και πολυπλοκότητας της ηλεκτροφορητικής εικόνας. Η ηλεκτροφόρηση πλασμιδίων πριν και μετά την επίδραση με EcoR1, έδειξε κοινή ηλεκτροφορητική εικόνα σε όλα τα στελέχη, ένα πλασμίδιο 23kb που μεταφέρει πιθανότατα χαρακτήρα μη εκφραζόμενο στο φαινότυπο. Η χρήση αντιορών του συστήματος IATS παραμένει η απλούστερη, αποδοτικότερη και πλέον αναπαραγώγιμη μέθοδος τυποποιήσεως της P. aeruginosa, σε συνδυασμό με μεθόδους μοριακής βιολογίας

Pseudomonas aeruginosa Slime Glycolipoprotein Is a Potent Stimulant of Tumor Necrosis Factor Alpha Gene Expression and Activation of Transcription Activators Nuclear Factor κB and Activator Protein 1 in Human Monocytes

Pseudomonas aeruginosa, an opportunistic pathogen, causes infections associated with a high incidence of morbidity and mortality in immunocompromised hosts. Production of tumor necrosis factor alpha (TNF-α), primarily by cells of monocytic lineage, is a crucial event in the course of these infections. During in vivo infections with P. aeruginosa, both lipopolysaccharide (LPS) and extracellular slime glycolipoprotein (GLP) produced by mucoid and nonmucoid strains are released. In the present study, we sought to explore the relative contributions of these two bacterial products to TNF-α production by human monocytes. To this end, fresh human monocytes and THP-1 human monocytic cells were stimulated with P. aeruginosa LPS or GLP. GLP was found to be a more potent stimulus for TNF-α production (threefold higher) by human monocytes than LPS. Moreover, its effect was comparable to that of viable bacteria. Quantitative mRNA analysis revealed predominantly transcriptional regulation. Electrophoretic mobility shift assays and transfection assays demonstrated activation of NF-κB and activator protein 1 (AP-1). NF-κB activation by GLP was rapid and followed the same time course as that by viable bacteria, suggesting that bacteria could directly activate NF-κB through GLP. Moreover P. aeruginosa GLP induced the formation of AP-1 complex with delayed kinetics compared with NF-κB but much more efficiently than the homologous LPS. These results identify GLP as the most important stimulant for TNF-α production by human monocytes. Activation of NF-κB and AP-1 by P. aeruginosa GLP may be involved not only in TNF-α induction but also in many of the inflammatory responses triggered in the course of infection with P. aeruginosa

A Molecular Lateral Flow Assay for SARS-CoV-2 Quantitative Detection

Since the onset of the SARS-CoV-2 pandemic, several COVID-19 detection methods, both commercially available and in the lab, have been developed using different biomolecules as analytes and different detection and sampling methods with high analytical performance. Developing novel COVID-19 detection assays is an exciting research field, as rapid accurate diagnosis is a valuable tool to control the current pandemic, and also because the acquired knowledge can be deployed for facing future infectious outbreaks. We here developed a novel gold-nanoparticle-based nucleic acid lateral flow assay for the rapid, visual, and quantitative detection of SARS-CoV-2. Our method was based on the use of a DNA internal standard (competitor) for quantification and involved RT-PCR, the hybridization of biotinylated PCR products to specific oligonucleotide probes, and detection with a dual lateral flow assay using gold nanoparticles conjugated to an anti-biotin antibody as reporters. The developed test allowed for rapid detection by the naked eye and the simultaneous quantification of SARS-CoV-2 in nasopharyngeal swabs with high specificity, detectability, and repeatability. This novel molecular strip test for COVID-19 detection represents a simple, cost-effective, and accurate rapid test that is very promising to be used as a future diagnostic tool

Efficacy of Fosfomycin-Containing Regimens for Treatment of Bacteremia Due to Pan-Drug Resistant Acinetobacter baumannii in Critically Ill Patients: A Case Series Study

Acinetobacter baumannii (AB) has evolved over the last decades as a major problem in carbapenem-resistant gram-negative nosocomial infections, associated with high mortality rates especially in the intensive care unit (ICU). Recent reports highlight the increasing prevalence of resistance to colistin, a last resort therapeutic option for carbapenem-resistant AB. We retrospectively evaluated the characteristics, treatment regimens and outcomes of twenty patients with pan-drug resistant (PDR) AB primary bacteremia hospitalized in the ICU of the University General Hospital of Patras, during a two-year period (October 2020–September 2022). The 28-day mortality reached 50%. Between survivors and non-survivors, no differences were found regarding age, gender, and Charlson comorbidity index (CCI). However, non-survivors had higher APACHE II scores and higher prevalence of septic shock and COVID-19 infection. A significantly higher percentage in the survivor group received Fosfomycin as part of the combination regimen. Inclusion of fosfomycin in the combination therapeutic regimen was associated with significantly better survival as compared to non-fosfomycin-containing regimens. In view of the increasing prevalence of PDR-AB infections in ICUs, its associated high rates of mortality and the lack of effective treatment options, the observed survival benefit with fosfomycin inclusion in the therapeutic regimen merits further validation in larger prospective studies

Laboratory Surveillance of <i>Acinetobacter</i> spp. Bloodstream Infections in a Tertiary University Hospital during a 9-Year Period

Multidrug-resistant Acinetobacter baumannii infections have become a threat for public health worldwide. The aim of the present study was to follow-up resistance patterns of Acinetobacter spp. bloodstream isolates in a Tertiary University Hospital over the last nine years, from 2014 to 2022. Susceptibility patterns were followed for the following antimicrobial agents: amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin, imipenem, meropenem, tigecycline, trimethoprim/sulfamethoxazole, and colistin. Minimal inhibitory concentration (MIC) values to ampicillin/sulbactam, cefepime, ceftazidime, minocycline, piperacillin/tazobactam were evaluated from 2020 to 2023. During the study period, 853 Acinetobacter spp. bloodstream infections (BSIs) were recorded, accounting for 5.36% of all BSIs. A. baumannii was isolated in 795 cases (93.2%), during the study period. Most BSIs were recorded in adult intensive care units (ICU) (46.2%) and medical wards (42%). Among A. baumannii isolates, 4.5% were multidrug-resistant, 84.7% were extensively drug-resistant, and 8.5% were pandrug-resistant. Resistance to carbapenems was over 95%. Resistance to tigecycline increased significantly during the last years of the study (2020–2022); A. baumannii isolates with MIC ≤ 2 μg/mL accounted for 28.5% of all isolates. Resistance to colistin exhibited an increasing pattern up to 42.2% in 2022. Increasing resistance rates and the evolution of pandrug-resistant isolates call for the urgent application of preventive and response actions

Pan-Echinocandin Resistant C. parapsilosis Harboring an F652S Fks1 Alteration in a Patient with Prolonged Echinocandin Therapy

The isolation of a pan-echinocandin-resistant Candida parapsilosis strain (anidulafungin, caspofungin, micafungin and rezafungin EUCAST MICs &gt; 8 mg/L) from urine of a patient following prolonged exposure to echinocandins (38 days of micafungin followed by 16 days of anidulafungin) is described. The isolate harbored the novel alteration F652S in the hotspot 1 region of fks1. Isogenic C. parapsilosis bloodstream isolates collected up to 1.5 months earlier from the same patient were susceptible to echinocandins (anidulafungin, caspofungin and micafungin EUCAST MICs 1&ndash;2, 1 and 1 mg/L, respectively) and contained wild-type FKS1 sequences. This is the first report of pan-echinocandin resistance in C. parapsilosis associated with an aminoacid change in hotspot 1 region of fks1