All posts by Anna Białecka

MICROBIAL HAZARDS IN POST-FLOOD SOILS – AN OVERVIEW


Karolina Furtak
14 May 2026

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Abstract: Becoming increasingly common across Poland and Europe. However, to date, microbiological studies have primarily focused on water intakes and the presence of indicator bacteria (i.e., fecal bacteria) in flood sediments. Data on soil microbial loads are lacking.
This short review synthesizes the available evidence on pathogen detection in soils after flooding and identifies gaps. Some researchers have reported a high diversity of bacterial, viral, and protozoan pathogens in river water and have shown that selected bacteria, such as Escherichia coli or Salmonella spp., may persist in post-flood soils for up to 44 days. The lack of systematic soil-focused research limits accurate risk assessment and may pose a significant threat to public health and food safety. Research priorities and mitigation strategies relevant to climate change–driven flood risk are proposed.

Autor: Anna Białecka
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ANTIMICROBIAL RESISTANCE IN KLEBSIELLA PNEUMONIAE: MECHANISMS, EPIDEMIOLOGY, AND EMERGING THREATS


Dorota Ochońska and Monika Brzychczy–Włoch
19 August 2026

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Abstract: Currently, one of the most serious threats to public health is the rapid spread of multidrug–resistant (MDR) and highly virulent Klebsiella pneumoniae (hvKp). In these strains, various antibiotic resistance genes (ARGs) are frequently detected, including several novel ones first identified in this bacterial species, such as carbapenemases of the KPC, NDM–1, and OXA–48 types. The widespread prevalence of environmental ARGs, which can be transferred between microbiota, particularly among clinical pathogens and human commensals, has significantly contributed to the emergence of antimicrobial resistance (AMR) in K. pneumoniae. Resistance is caused by mechanisms such as drug inactivation, increased efflux, or altered binding to target sites. Moreover, this resistance is further enhanced by the production of various beta-lactamases, mainly extended–spectrum beta-lactamases (ESBLs), or by biofilm formation. Particularly concerning in K. pneumoniae, the main species representing the carbapenemase–producing Enterobacterales (CPE) group, is the emergence of plasmid–mediated resistance to carbapenems and polymyxins, which are considered “last–resort drugs” for treating infections caused by these pathogenic microorganisms. The growing resistance of K. pneumoniae to antibiotics and other antimicrobial agents remains one of the most important problems in epidemiological surveillance, microbiological diagnostics, and the global treatment of infections. The high mortality rate among infected patients and the difficulty in treating infections caused by MDR K. pneumoniae have led to this bacterium being classified as one of the most common and dangerous human pathogens in both Polish and global healthcare. This article characterizes the factors determining antibiotic resistance in K. pneumoniae, both in terms of biochemical mechanisms and molecular features. In addition, the current epidemiological situation regarding the spread of invasive, resistant K. pneumoniae isolates in Europe and Poland is described, and treatment regimens for infections caused by these high–alert pathogens are presented.

Autor: Anna Białecka
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TRYPSIN-ACTIVATED PARASPORAL PROTEINS FROM NATIVE BACILLUS THURINGIENSIS ISOLATES REDUCE STAPHYLOCOCCUS AUREUS VIRULENCE AND BIOFILM FORMATION IN VITRO


Talat A. El-kersh, Nada F. Almebairik, Hazem K. Ghneim, Abdullah A. Alyousef, Yazeed A. Al-Sheikh and Mourad A. M. Aboul-Soud
19 August 2026

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Abstract: Antibiotics are pivotal for treating Staphylococcus aureus infections, but overuse has led to multidrug-resistant (MDR) strains, necessitating alternative strategies. Targeting virulence factors, rather than bacterial survival, offers a promising approach to combat resistance. This study evaluated the in vitro effects of native, non-insecticidal Bacillus thuringiensis (Bt) parasporal crystal proteins (PCPs), in protoxin (PT) and trypsin-activated (AT) forms, on S. aureus virulence gene expression and biofilm formation. Fourteen Bt PCPs were isolated and prepared as PT and AT forms. Their impact was assessed using LacZ promoter fusion assays for hla (alpha-hemolysin), spa (protein A), and RNAIII (a key virulence regulator), supplemented by quantitative β-galactosidase assays. Biofilm formation was quantified and normalized to planktonic growth (Normalized Biofilm Index, NBI) to distinguish specific antibiofilm activity from growth inhibition. AT-PCPs from Bt strains M11, M78, M91, M154t1, and A11 significantly downregulated hla, spa, and RNAIII expression (log₂ fold changes up to –4.88, p < 0.001) and reduced biofilm formation (NBI reduction up to 57%, p < 0.001). AT proteins exhibited no hemolytic activity and had MIC values >100 μg/mL, confirming antivirulence effects at sub-inhibitory concentrations. PCR screening revealed the absence of cyt1 genes in four of five active isolates, supporting Cry-mediated targeting. These in vitro findings suggest that trypsin-activated PCPs can disrupt critical virulence pathways in S. aureus. Trypsin-activated Bt PCPs attenuate virulence and biofilm formation in S. aureus in vitro, highlighting their potential as leads for novel antivirulence strategies. These proteins show potential as candidates for standalone or adjuvant strategies alongside conventional antibiotics in the fight against MDR infections, pending further validation. Further research is needed to elucidate their mechanisms, assess their efficacy in vivo, and evaluate enzymatic activation by host-derived proteases. These in vitro results highlight the potential of Bt-derived PCPs as novel virulence-targeting leads, though further research is needed to identify the active component(s), elucidate mechanisms, and evaluate efficacy in vivo.

Autor: Anna Białecka
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DETECTION OF VIRULENCE GENES AND ABC GENOTYPES IN CANDIDA ALBICANS ISOLATES FROM CANDIDEMIA PATIENTS


Burak Pural, Sevda Ozel Yildiz, Gonca Erkose Genc
19 August 2026

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Abstract: Candidemia is the most common form of invasive fungal infection, and is associated with high mortality rates particularly in intensive care patients. In this study, 50 C. albicans strains isolated from blood samples were genotyped by 25S intron analysis, and the presence of virulence genes was investigated by PCR. Genotyping revealed that 28 isolates (56%) were genotype A, 14 (28%) genotype B, and eight (16%) genotype C. The SAP1 gene was detected in 96% of isolates, SAP2 and SAP4 in 98%, ALS1 and HWP1 in 92%, and PLB1 in 94%. A comprehensive understanding of Candida virulence factors, particularly in C. albicans which is the most prevalent Candida species acting as both a commensal organism and an opportunistic pathogen, is essential for improving diagnostic methods, and guiding the design of novel antifungal agents targeting virulence mechanisms.

Autor: Anna Białecka
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PATHOGENIC BACTERIA VARIATION IN HYDROELECTRIC RESERVOIRS: CASE OF KOSSOU, TAABO AND FAÉ IN CÔTE D’IVOIRE


Gogbé Jean-Luc Tiémoko, Nouho Koffi Ouattara, Bahou Roger Dehe, Ouéméla Venance Allais Ban, Cyr-Kevin Yao Kouamé, Allassane Ouattara
19 August 2026

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Abstract: Recent studies have shown that the Taabo, Kossou, and Faé reservoirs are contaminated by faecal pollutants, which could pose health risks to users due to a potentially high abundance of pathogenic bacteria. Accordingly, a monitoring study was planned to assess variation in pathogen abundance, including Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), in these reservoirs. Water sampling was conducted between February and October of the same year along a linear transect in each reservoir. Pathogenic bacteria were analyzed using culture and polymerase chain reaction (PCR) methods. The primer pairs PA-SS-F/PA-SS-R were used for P. aeruginosa, and 16S rRNA-F/16S rRNA-R were used for S. aureus. Overall, the median concentrations of P. aeruginosa and S. aureus ranged from 0.97 and 2.57 Log CFU/100 mL. The highest concentrations of these bacteria were generally recorded during the rainy periods in June, July, September, and October. Spatially, the highest concentrations were found in the shore areas of the different reservoirs. The results indicated weak correlations between the concentrations of these pathogenic bacteria. To preserve the integrity of these hydroelectric reservoirs, it is advisable to establish safety zones around them and to treat wastewater prior to discharge.

Autor: Anna Białecka
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Current Issue

Current Issue

Advancements of Microbiology
Volume 65 (2026): Issue 2

Publisher

PTM

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