Comparison of biofilm production and virulence genes distribution among human and canine isolates of Staphylococcus aureus.

Background: Staphylococcus aureus is an important human and animal pathogen that can cause a wide range of infections due to numerous virulence factors. Aims: The aim of this study was to compare biofilm formation ability with different virulence factors such as bacterial motility, genes encoding biofilm associated proteins, and Panton-Valentine leukocidin (PVL) among human and canine isolates of S. aureus. Methods: A total of 60 human (30 methicillin sensitive S. aureus (MSSA) and 30 methicillin resistant S. aureus (MRSA)) and 17 canine (all MSSA) isolates of S. aureus were tested for the capability of biofilm production, motility assay, and presence of genes encoding virulence factors: ica (encoding intercellular adhesion), bap (encoding biofilm-associated protein), fnbA (encoding fibronectin-binding protein A), cna (encoding collagen-binding protein), and pvl (encoding PVL). Results: Animal isolates of S. aureus performed better biofilm production than the human strains (P=0.042), as well as human MSSA compared to the MRSA isolates (P=0.013). Our results showed that cna, fnbA, and ica genes (67.5%, 66.2%, and 42.9%, respectively) were more prevalent than bap and pvl genes (0%, and 7.8%, respectively). The ica gene was significantly more prevalent in human isolates compared to animal isolates (n=31/60 vs. n=2/17, P=0.008), whereas the cna gene was more frequent in animal isolates than in human ones (n=15/17 vs. n=37/60, P=0.0201). Significant correlations were found between the biofilm formation of animal isolates, and the presence of fnbA (P=0.029) and ica genes (P=0.001). Conclusion: This study showed a correlation between biofilm production and the presence of certain biofilm-related genes in animal isolates, as well as stronger biofilm production among MSSA human and animal isolates.

The emergence of multi-drug-resistant bacteria causing healthcare-associated infections in COVID-19 patients: a retrospective multi-centre study.

INTRODUCTION: We evaluated the prevalence, aetiologies and antibiotic resistance patterns of bacterial infections in hospitalized patients with laboratory-confirmed SARS-CoV-2. We also investigated comorbidities, risk factors and the mortality rate in COVID-19 patients with bacterial infections. METHODS: This retrospective observational study evaluated medical records of 7249 randomly selected patients with COVID-19 admitted to three clinical centres between 1st January 2021 and 16th February 2022. A total of 6478 COVID-19 patients met the eligibility criteria for analysis. RESULTS: The mean age of the patients with SARS-CoV-2 and bacterial infections was 68.6 ± 15.5 years (range: 24-94 years). The majority of patients (68.7%) were older than 65 years. The prevalence of bacterial infections among hospitalized COVID-19 patients was 12.9%, most of them being hospital-acquired (11.5%). Bloodstream (37.7%) and respiratory tract infections (25.6%) were the most common bacterial infections. Klebsiella pneumoniae and Acinetobacter baumannii caused 25.2% and 23.6% of all bacterial infections, respectively. Carbapenem-resistance in Enterobacterales, A. baumannii and Pseudomonas aeruginosa were 71.3%, 93.8% and 69.1%, respectively. Age >60 years and infections caused by ≥3 pathogens were significantly more prevalent among deceased patients compared with survivors (P<0.05). Furthermore, 95% of patients who were intubated developed ventilator-associated pneumonia. The overall in-hospital mortality rate of patients with SARS-CoV-2 and bacterial infections was 51.6%, while 91.7% of patients who required invasive mechanical ventilation died. CONCLUSIONS: Our results reveal a striking association between healthcare-associated bacterial infections as an important complication of COVID-19 and fatal outcomes.

Clinical and molecular characteristics of OXA-72-producing Acinetobacter baumannii ST636 outbreak at a neonatal intensive care unit in Serbia.

AIM: To describe an Acinetobacter baumannii outbreak among preterm neonates in a neonatal intensive care unit (NICU) in Serbia. METHODS: A case-control study was conducted in the NICU at the Institute of Neonatology, Belgrade, Serbia. The case definition of A. baumannii bloodstream infection (BSI) was blood culture confirmation of systemic infection. Isolation, identification and susceptibility testing were performed using conventional methods. Molecular characterization of isolates included resistance gene detection, pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Outcomes and clinical and demographic data were obtained from patients' medical records. An infection prevention team was formed and infection control interventions were implemented. FINDINGS: During the outbreak period (May-July 2018), there were 13 cases of A. baumannii BSI among 82 hospitalized neonates. All A. baumannii strains were carbapenem resistant and susceptible to colistin. Molecular characterization of the isolates revealed that they harboured blaOXA66 and blaOXA72 beta-lactamases and belonged to sequence type 636, while the PFGE pattern indicated clonal spread. Lower gestational age, lower Apgar score, vaginal delivery and mechanical ventilation were risk factors for A. baumannii infection. Four patients died, eight patients were treated successfully with colistin, and one patient with sepsis and meningitis on dual ampicillin-sulbactam and colistin therapy recovered with sequelae. The outbreak was eventually controlled by reinforcement of the infection control measures based on a multi-tiered interventional approach. CONCLUSION: This is the first description of an outbreak of BSI among preterm neonates caused by A. baumannii blaOXA66/blaOXA72/ST636 in Serbia.

Trends in macrolide resistance of respiratory tract pathogens in the paediatric population in Serbia from 2004 to 2009.

We report the first study of macrolide resistance in respiratory tract pathogens in a Serbian paediatric population. It included 5293 Streptococcus pneumoniae, 4297 Streptococcus pyogenes, 2568 Moraxella catarrhalis and 1998 Haemophilus influenzae isolates derived from the respiratory tract and 110 invasive isolates from children aged up to 18 years during 2004-2009. Over the 6-year period, a significant increase (P < 0·01) in macrolide resistance was found in both S. pneumoniae and S. pyogenes that reached 45% and 19%, respectively, in 2009. In the same period, consumption of macrolides increased continually from 2·46 to 5·8 defined daily dose/1000 inhabitants per day. The increase in macrolide resistance in S. pyogenes correlated with consumption of total macrolide and long-acting macrolides (r = 0·879, P = 0·05 and r = 0·922, P = 0·026, respectively). A similar trend was observed in pneumoccoci, although it did not reach statistical significance. The growing problem of macrolide resistance in pneumococci and S. pyogenes in Serbia requires further vigilant surveillance.

Typing of macrolide resistant group A streptococci by random amplified polymorphic DNA analysis.

OBJECTIVE: Several studies of group A streptococci (GAS) have revealed that a small number of dominant resistant clones might be responsible for the spread of Streptococcus (S.) pyogenes resistance to macrolides. We aimed to determine the genetic diversity of macrolide resistant group A streptococci (MRGAS), isolated from patients with pharyngitis in Serbia. MATERIALS AND METHODS: The clonal relationships among 76 MRGAS isolates collected during 2008 were studied using two molecular typing methods: emm typing and random amplified polymorphic DNA (RAPD) analysis. Isolates that share the same emm type and RAPD pattern were considered to belong to the same clone. RESULTS: Out of 7 distinct emm types identified, the 3 most frequently occurring overall were emm12, emm75 and emm77 (> 90% of isolates). Although as many as 26 different RAPD patterns were found among the isolates studied, two clones with emm12 and emm77 accounted 32 out of 76 (42%) isolates. CONCLUSIONS: The results indicate a polyclonal spread of erythromycin-resistant Streptococcus pyogenes in our country. Furthermore, predominance of two clones, particularly among emm12 and emm77 strains indicates that erythromycin-resistant GAS of the same clonal origin are widely distributed in Serbia.

[Child obesity: assessment and follow-up]. / Procena i pracenje gojaznosti u decjoj populaciji

The aim of the study of 1083 children (aged 7-11) was to determine a minimum of somatometric parameters sufficient for a realistic assessment and follow-up of obesity in this population. In other words, we wanted to make the most rational choice of parameters necessary for correct application of the "statistical" definition of obesity. To estimate obesity in children, we used parameters such as body height, body weight, skinfold thickness measured at five points as well as the indices - relative body weight and body mass index. We then examined which of the indices that have been used had a greater correlation with the sum of skinfold thicknesses. Research results have shown that in order to estimate child obesity for epidemiological purposes, it is sufficient to determine only body height, body weight and body mass index. These parameters are also sufficient for the purpose of planning and realization of programs for the prevention of obesity.

[Nutrition and physical activity of obese and properly nourished children]. / Ishrana i fizicka aktivnost gojazne i normalno uhranjene dece.

The aim of the study which included 2297 children (aged 5-18), was to determine the role of nutrition and physical activity in the occurrence of obesity in this population. Nutritional status of children was estimated by body mass index. In order to examine nutrition we used a quantitative questionnaire, and physical activity was examined by a specially designed questionnaire (made according to the WHO recommendations). The obtained results showed that abundant nutrition and insufficient physical activity played a significant role in the occurrence of child obesity.

[Comparative study of nutritional status of school-age children fed at home and in schools]. / Uporedna studija uhranjenosti dece skolskog uzrasta u uslovima porodicne i drustvene ishrane.

Comparative study of the nutritional status of schoolchildren fed at home and in schools is a part of a broader study conducted in primary schools in Belgrade which comprised 1083 children, aged 7-11. The aim of investigation was to determine whether the nutritional status of children fed at home was different from the nutritional status of those fed in schools, and to determine the reasons of possible differences. The investigation concerned 756 children. The nutritional status of children was assessed by anthropometric measures (BH,BW,AC,AMC,ST,RBW,BMI)% of fat), haemoglobin concentration in the serum and the value of blood pressure. The quality of nutrition in each child was assessed by a questionnaire and his/her daily energy expenditure calculated on the basis of individual daily physical activities. Other date have also been taken into consideration (economical status of a family, education in nutrition and in general, etc.). Results show that nutrition in schools is not adjusted to RDA and that children fed in schools are worse nourished, in lesser percent obese and have lower level of BP than the coevals fed only at home. The differences are visible and statistically significant among the oldest in this age group. They are the result of differences in the individual whole day nutrition and several other factors which have been taken into account.