Nontyphoidal Salmonella serotypes are diverse in their host range and vary in their pathogenic capability. They can cause huge economic losses due to human and animal infections worldwide. Biofilms are essential to the survival of microorganisms in their natural habitat, either the environment or the human body. This study aimed to investigate the ability of nontyphoidal Salmonella strains isolated from contaminated food of animal origin to produce biofilm in different incubation conditions such as nutrient media and incubation temperatures. Bacterial strains analyzed in this study were recovered from the food samples of animal origin in the Public Institution Veterinary Institute of the Republic of Srpska "Dr. Vaso Butozan" between 2017 and 2018 year. Biofilm production was determined by crystal violet assay in a microtiter plate in Trypticase-Soy (TSB) and Brainheart Infusion (BHI) broths during overnight incubation at 4 ℃, 25 ℃, and 37 ℃. A total of 30 Salmonella isolates were detected in 730 samples (4.1%), mainly from chicken meat (27 isolates). S. Infantis (14 isolates) and S. Enteritidis (12 isolates) were the two most common serotypes. As expected, none of the isolates were strong biofilm producers at all three incubation temperatures in both broths. Although the refrigeration temperature was the most unfavorable for biofilm creation, there were no significant statistical differences between tested incubation temperatures in BHI broth (p ≥ 0.05). In TSB broth, a significant statistical difference was found between isolates incubated at all three temperatures (p < 0.001, p < 0.001, p < 0.001). The lowest temperature was the least suitable for the formation of biofilm, whereas ambient temperature was the most favorable for biofilm production. When we compared the biofilm production in TSB and BHI broths, we observed that TSB was the better broth for efficient biofilm production only at 25 ℃ and 37 ℃ (p <0.001, p=0.049).  The temperature and medium composition are important for biofilm production. Salmonella's ability to form biofilms at ambient and refrigeration temperatures is significant in the poultry, catering, and household industries, allowing for long-term bacterial persistence.

The human cytomegalovirus (CMV) is a ubiquitous pathogen and an important factor contributing to morbidity and mortality in patients with hematologic malignancies. Serological demonstration of prior exposure to CMV is essential in this population. A number of factors including gender and age may influence CMV seropositivity in patients with B-cell neoplasms as they do in healthy individuals. Herein, we have investigated CMV serostatus in non-transplanted patients with lymphoid B-cell malignancies. Significance of gender, age, and the underlying type of lymphoid cancer in connection to seroprevalence were examined. Blood samples of seventy adult patients were screened for CMV IgG and IgM antibodies by means of an enzyme linked immunosorbent assay (ELISA). Group comparisons were performed using pertinent statistical tests and data were analyzed using IBM SPSS 20.0 statistical software. The overall CMV seroprevalence was 88.6%. The acquisition of CMV was greater in females (p=0.266) and older patients (p=0.07) than male and younger individuals. The largest seroprevalence was evidenced in patients >60 years (95.2%). Age was ostensibly co-incremental with the degree of CMV exposure (p=0.054). The extent of CMV seropositivity and the particular type of B-cell malignancy were not related (p=0.339). CMV seroprevalence in patients with lymphoid B-cell neoplasms is higher in females and older individuals, without predilection for a particular type of underlying neoplasm.

Carbapenem-resistant Acinetobacter baumannii (CRAB) is endemic in Serbia. CRAB initially emerged around the 2000s, and since then, carbapenemases have played a crucial role in its appearance. Oxacillinases (OXAs) are the most prevalent carbapenemases detected in CRAB isolates collected from patients admitted to Serbian hospitals. Among acquired OXA enzymes, OXA-23 and OXA-24 are the most commonly found. NDM-1-producing CRAB was also detected. The predominant OXA-23 and OXA-24 producers are associated with multilocus sequence typing (MLST) Pasteur scheme sequence type (ST) 2 and ST492 clonal strains of the international clone (IC) II. Isolated CRABs are typically multidrug-resistant (MDR) strains which complicates the treatment options. This review aims to go through the molecular epidemiology of CRAB clinical isolates in Serbia, as one of the most important aspects for implementing infection control measures and adjusted antimicrobial treatment strategies in hospital settings that could confine clonal CRAB spread.

Streptococcus pneumoniae is the most common causative agent of community-acquired pneumonia, which may progress to invasive pneumococcal infections when the pathogen penetrates the pleura or bloodstream, leading to sepsis. This study aimed to determine the distribution of serotypes among patients with pneumonia and analyze the invasive serotypes’ re-sistance to antibiotics. A retrospective research study was conducted at the Department of Microbiological Diagnostics at the Institute for Pulmonary Diseases of Vojvodina in Sremska Kamenica from January 2015 to December 2020. Isolates were obtained from the blood and pleural fluid of pneumonia patients. Antimicrobial susceptibility was determined using the disc diffu-sion method and gradient tests. Serotype determination was performed by the National Reference Laboratory for Strepto-cocci (NRL) using the Quellung reaction and capsular polysaccharide antisera. During the study period, 66 isolates were collected from an equal number of patients. Of all the patients, 46 (69.7%) were male, and 20 (30.30%) were female. Among these, 33 (50%) were adults, and 33 (50%) were elderly. Pleural fluid yielded 40 (60.6%) isolates, while blood samples provided 26 (39.4%) isolates. There were 21 (31.8%) isolates from the summer period and 45 (68.1%) from the winter period. The isolates exhibited high resistance to co-trimoxazole (39.4%), penicillin (33.3%), erythromycin (28.78%), and clindamycin (25.8%), while they remained fully sensitive to vancomycin, teicoplanin, and linezolid. A total of 11 distinct serotypes were detected: 1, 3, 4, 7F, 9N, 10A, 14, 15A, 19A, 19F, and 23B. Invasive serotypes displayed substantial resistance to co-trimoxazole, penicillin, erythromycin, clindamycin, levofloxa-cin, and moxifloxacin. The highest resistance was observed in serotypes 19F, 15A, and 14..

In the post-COVID-19 era, there has been a notable surge in the development of mRNA vaccines. These vaccines are not only targeting various pathogens beyond SARS-CoV-2 but also hold promise in treating cancer and genetic disorders. These type of vaccines are revolutionizing vaccinology through their inherent possibility for rapid pandemic response, high efficacy, minimal side effects, and cost-effectiveness. Achieving these benefits hinges on seamlessly integrating mRNA production steps, from plasmid DNA (pDNA) design and antigen cloning, in vitro transcription to lipid nanoparticle formulation. A critical initial step in mRNA vaccine production is pDNA cloning vector design. The vector should be carefully constructed considering a copy number of plasmid, vector backbone with a promoter, the origin of replication, multiple cloning sites, polyadenylation signal, and markers for selection. However, despite careful design, challenges like poly-A tail deletion may arise, prompting the exploration of stable large-size and low-copy vectors, as well as linear and bacteriophage vectors. Additionally, for large-scale production and regulatory compliance, vector systems must be scalable and well-documented. This overview aims to elaborate upon the intricacies in pDNA cloning vector design. The focus is on achieving accurate insert sequence, especially those encoding the complex antigens and gene expression, highlighting the critical role of pDNA design in ensuring vaccine effectiveness. Although commercial vectors and automated synthesis facilitate gene construction, challenges still exist. This emphasizes that a multifaceted approach, combining molecular biology techniques, computational tools, and collaboration with experts in microbiology, molecular biology, and vaccine development, is required for successful mRNA vaccine development.

Escherichia coli is by far the leading cause of community-acquired UTIs. Its emerging antimicrobial resistance, along with the existence multidrug-resistant (MDR) strains is one of the most difficult global healthcare challenges. In Europe, including Serbia, E. coli isolates obtained from patients with acute uncomplicated urinary tract infections (UTIs) have increasing antimicrobial resistance, particularly to ciprofloxacin and trimethoprim-sulfamethoxazole. Pivmecillinam, the oral prodrug of the penicillin derivative mecillinam, was introduced in national and international protocols around the globe for UTIs treatment in ambulatory settings after showing high efficiency for uncomplicated low UTIs. During its application in various European countries, mecillinam has shown a satisfactory clinical effect against uropathogenic E. coli. Thus, it is commonly used as the anibiotic of choice for the empirical management of UTIs, mostly due to its low resistance rates and low damaging effects on the gut microbiota as a pro-drug. Research showed that mecillinam exhibits high antimicrobial activity against MDR E. coli strains, such is the case in metallo-β-lactamase (MBL)-producing isolates (both NDM-1 and IMP types) and OXA-48-like-positive strains. Mecillinam is yet to be registered in Serbia, in order to be tested as a potential first-choice antibiotic for UTI caused by E. coli. Thus, we review the current literature data on mecillinam’s antibacterial effect in this particular bacteria.

The “silent pandemic” – a WHO-coined phrase that relates to the rise and spread of antimicrobial resistance is a phenomenon so striking that in spite of living in the most prosperous times, we are threatened to return to the preantibiotic era when even the simplest of interventions and infections were possibly deadly. One of the possible solutions could be the application of natural predators of bacteria – bacteriophage therapy. Discovered over a century ago, phages have been studied extensively and have become irreplaceable tools in laboratory work. The knowledge they helped to generate is still enlarging, and was responsible, at least in part, for creating the whole scientific discipline of Molecular biology. Their application on the other hand has not been as continuous and fruitful. On the contrary, the history of phage therapy is one of rise and fall, enthusiasm and acceptance as well as rebuttal and oblivion, scientific misconceptions and dogmatism, bad corporate investments, politics and ideologies. As today we are equipped with far more knowledge on the biology of phages, bacteria and resistance than early phage enthusiasts, it is justified to attempt phage application once again. Here we elaborate on the early years and very first attempts of phage therapy and the troubles rising from those days as they serve as excellent cornerstones for future endeavors in the field. In parallel, the current state-of-the-art of phage therapy in different parts of the world is also presented.

Viral infections such as Epstein-Barr virus (EBV) and Herpes simplex virus (HSV) represent significant complications in patients with haematological malignancies and increase the frequency of morbidity and mortality. These infections represent one of the main factors of unsuccessful treatment; therefore, regular monitoring of active viral infections is necessary. The work aimed to determine the frequency and dynamics of active EBV and HSV infection in patients with haematological malignancies, monitored at the Institute of Microbiology and Immunology, Faculty of Medicine University of Belgrade over two years. This study included 35 patients treated at Hematology Clinics of the University Clinical Center of Serbia. Patients were monitored during 2020-2021. Ten blood samples were taken from each patient during monitored period. The samples were taken in a time interval between 2 weeks and three months, depending on the arrival of patients at medical controls. The first sample is marked with the first measurement of blood drawn during 2020 for each patient. The second measurement was a second blood sample taken in the previously mentioned time interval, and so on up to the tenth sample marked as the tenth measurement. For the detection of EBV DNA, the “in-house” PCR method was used to detect the EBNA-1 gene. According to the manufacturer’s instructions, the commercial kit Ampli Sens® HSVI, II-FRT was used for HSV DNA detection (InterLabService, Moscow, Russia). The lowest frequency of EBV infection was during the second measurement (8.57%), while the highest was during the eighth and tenth measurements (31.43%). The highest frequency of HSV infection was during the eighth measurement (5.71%), while during the third, fifth and ninth measurements, none of the subjects had positive PCR for HSV DNA. A statistically significant difference was found in the frequency of EBV infection in later measurements compared to earlier measurements (p=0.002). In contrast, this was not the case in the study of HSV frequency infection (p=0.750). This study presents the dynamics of the frequency of active EBV and HSV infection in patients with haematological malignancies in two-year period. The frequency of active EBV infection was significantly higher compared to HSV infection.