Acta Microbiol. Hell., Volume 69, Issue 4 (December 2024) – 5 articles

Biofilms are bacterial communities on surfaces within an extracellular matrix. Targeting biofilm-specific bacteria is crucial, and natural compounds with reported antibiofilm activity have garnered significant interest. The study evaluated the antibacterial and antibiofilm activity of E. senegalensis leaf extract against multidrug-resistant (MDR) Gram-negative bacteria, including S. Typhimurium, S. Typhi, S. Enteritidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The leaf extract was prepared using aqueous and ethanol solvents, and qualitative phytochemical screening revealed the presence of various bioactive compounds such as tannins, saponins, cardiac glycosides, flavonoids, terpenoids, alkaloids, anthraquinone, reducing sugar, and ketones. A Kirby–Bauer disc diffusion assay was performed to test the susceptibility of antibiotics, and the antibacterial efficacy of the aqueous and ethanol extracts of E. senegalensis was determined using the cup-plate method, while the antibiofilm activities were determined using the crystal violet titer-plate method. The aqueous and ethanol extracts of E. senegalensis revealed the presence of tannins, saponins, cardiac glycosides, flavonoids, terpenoids, alkaloids, anthraquinone, reducing sugar, and ketones. The study found that the Gram-negative bacteria isolates that were MDR were S. Typhimurium, S. Enteritidis, and P. aeruginosa, while K. pneumoniae was resistant to beta-lactam and fluoroquinolones, and S. typhi was sensitive to all antibiotics tested. Statistically, susceptibility to antibiotics had an inverse, weak, and significant relationship with biofilm production (r = −0.453, −0.106, −0.124, −0.106, −0.018, n = 10, p < 0.05). The aqueous extract showed good biofilm inhibition against K. pneumoniae and P. aeruginosa, and poor biofilm inhibition against S. Enteritidis, while S. Typhimurium and S. Typhi exhibited no biofilm inhibition. The ethanol extract did not demonstrate any antibiofilm activity against the tested Gram-negative pathogens. The study suggests that the Gram-negative bacteria’s capacity to form biofilms is negatively associated with their antibiotic resistance phenotypes, and the aqueous extract of E. senegalensis exhibited moderate antibiofilm activity against K. pneumoniae, P. aeruginosa, and S. Enteritidis. Full article

Tuberculosis has had a long-standing prevalence in Greece over the last century, going hand in hand with the country’s overall socioeconomic situation. The current study explores aspects of tuberculosis in Greece since the interwar period and up to the present. Apparently, ignorance of the nature of the disease coupled with false medical perceptions sealed the fate of patients while unwittingly influencing public opinion and making societies hostile toward patients. Such paradigms are of great and timeless value for the cohesion and functioning of societies, not excluding modern ones. Although the present-day situation in Greece is utterly different from that in the previous century, considering the limited number of cases and minimal impact of the disease, new challenges have emerged, such as the under-reporting of cases, the emergence of multidrug-resistant tuberculosis, latent tuberculosis or the management of large refugee flows in the Eastern Mediterranean involving citizens from countries with a high prevalence of the disease. On the other hand, the study of tuberculosis is nowadays more urgent than ever, given the global concerns regarding the future of the disease in the midst of the COVID-19 pandemic, which has put enormous pressure on national health systems. Full article

The United States Centers for Disease Control and Prevention (CDC) has categorized Clostridioides difficile infection (CDI) as a significant concern in extended-care facilities, hospitals, and outpatient clinics. However, little is known about CDI in low- and middle-income countries. This study determined CDI prevalence and impact in outpatient adults presenting with diarrhea in Nigeria. Toxigenic culture and PCR were used to detect and validate C. difficile. Prior antibiotic use, medical history, and demographic data were also obtained. Descriptive and inferential statistics were used for data analysis. The patient demographics were 35.48% (22/62) for the 18–24 years age group and 32.26% (20/62) for both the 25–30 years age group and the 31+ years group, with an average age of 29.7 years. Forty-eight percent of the patients (30/62) tested positive for CDI, and the prevalence increased with age. Most patients (86.67%, 52/60) reported moderate/severe cases of diarrhea and 67.7% had no knowledge of antibiotics. The results showed that 62.30% of the cases were hospitalized with the duration of diarrhea being significantly associated (r = 0.98, p ˂ 0.001) with the length of hospitalization. These results suggest that C. difficile is common among diarrhea patients in this population and that Nigerian hospitals’ infection prevention and control measures must include this pathogen. Full article

Neutrophil gelatinase-associated lipocalin (NGAL) is a protein secreted by activated neutrophils and certain tissues. The aim of this study was to investigate the prognostic role of urinary neutrophil gelatinase-associated lipocalin (uNGAL) in hospitalized COVID-19 patients with regard to mortality. The prospective observational cohort study involved 86 hospitalized adult COVID-19 patients. Patients’ urine samples were collected upon admission and 48–72 h after admission. General anamnesis and clinical status information were obtained from medical records. Within 24 h of sample collection, urine aliquots were centrifuged, the supernatant was separated, and samples were frozen at −80 °C until uNGAL concentration measurement, which was performed within two years of sample collection. The patients were categorized into groups based on disease outcome (survived/deceased). Data analysis was performed to identify predictive factors and diagnostic indicators for the unfavorable outcome group using logistic regression and ROC curve methods. Logistic regression associated age, cardiomyopathy, invasive mechanical ventilation, and uNGAL concentration (follow-up sampling) with mortality. ROC analysis identified uNGAL concentration (follow-up sampling) as an indicator of mortality, with a cut-off value of >23.8 ng/mL. This study concludes that there is an association between disease outcome and uNGAL concentration in COVID-19 patients. However, understanding the dynamics of uNGAL concentration during COVID-19 remains limited, which is crucial for its effective clinical application. Full article

Newcastle disease, which affects poultry and is endemic in many nations across the world, is caused by Avian Paramyxovirus-1 (APMV-1). This experimental study was conducted from January to June 2021 at the National Veterinary Institute (NVI) to evaluate the virus viability and antibody titer of Newcastle disease vaccines (Hichner’s B1, Lasota, and ThermostableI2) stored at different temperature storage conditions. Chickens (12 treatment groups and 1 control group) were vaccinated and challenged with the virulent ND virus (0.5 × 10^6.5 embryonic lethal dose fifty (ELD₅₀)). The immune responses (antibody titers) of chickens were evaluated using hemagglutination (HA) and hemagglutination inhibition (HI) assays. The Newcastle disease vaccines (Hachiner’s B1 (ND-HB1), ND-Lasota, and ND-Thermostable I2) stored at +4 °C HI-induced antibody titers of 151 (±103.3), 136 (±53.4), and 145 (±91) on day 14, respectively, whereas on day 21, they increased to 160 (±82) for ND-HB1 and 144 (±74.5) for ND-Lasota. ND-Thermostable I2 showed a decrement to 133 (±44.8). All three vaccines stored at different temperature storage conditions (+4, +23, and +30 °C) used in this experiment induced antibody titers greater than 128 on day 28 post-vaccination, except the Newcastle disease vaccine Thermostable I2 stored at +30 °C. The vaccines collected from private veterinary drugstores (customer vaccines Hachiner’s B1 and ND-Thermostable I2) used in this experiment induced very low antibody titers, less than 128 antibody titers, from days 14 to 21. Statistically significant induced mean antibody titers were observed for chickens that received vaccines stored at different temperature storage conditions for 72 h (p < 0.05), except for the ND-HB1 mean HI-induced antibody titer at days 7 and 28. Further, vaccine protection was confirmed by inoculation of both the vaccinated (treatment groups) and control groups by the virulent ND virus, where the control group started dying three days post-challenge but all chicks that received the vaccines survived. Overall, this study showed the impact of temperature storage conditions on the antibody titer and their effect on the titer of the viable virus in the vaccine, and thereby its protective capacity, warranting appropriate cold chain management of the vaccines along the value chain. Full article