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Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens causing hemorrhagic colitis and hemolytic uremic syndrome (HUS) in children and the elderly. Stool samples were collected from 180 children hospitalized in five pediatric centers in Poland in 2018–2022. Direct stx1/stx2 gene detection by PCR in feces and E. coli isolates was performed. Antibiotic susceptibility was tested according to EUCAST v.12. Randomly selected isolates were serotyped with O157 antiserum and genotyped by pulsed-field gel electrophoresis (PFGE). A total of 44 E. coli isolates were confirmed as STEC by PCR. Among them, 84.4% were positive for stx2, and equally 6,8% for only stx1 and both stx1 and stx2 genes. The stx1 gene was also found in one Citrobacter freundii isolate. E. coli serotype O157 was present in 97.6% of the isolates. STEC infections most often occurred between June-October with a peak in July and August (51%). The highest, 77.8% of STEC isolates were found in the 1–5 years old group. No extended-spectrum β-lactamases (ESBL) were found. Resistance only to amoxicillin/clavulanic acid (24.4%), piperacillin/tazobactam (3%), cefotaxime (6%), gentamicin (6%), ciprofloxacin (3%), azithromycin (3%), trimethoprim/sulfamethoxazole (24,2%) was detected. PFGE analysis showed 18 PFGE types with no clonal distribution. Eight isolates with A, B, and C PFGE types showed genetic relatedness in the type with no detection of transmission way of distribution. STEC strains pose a serious threat to human health, therefore demographic and epidemiological characteristics are crucial for their surveillance.

Anaerobic bacteraemia is not frequent (1.2–13.7%), but is associated with a high mortality rate of 16–27%. Anaerobic infections including bacteraemia nearly always arise from contamination by endogenous bacteria into contiguous or other sites like gastrointestinal tracts, genito-urinary tracts, abscesses etc. Factors leading to anaerobic bacteraemia are mainly surgical procedures, crush injuries, the presence of foreign bodies, tissue necrosis, tumours, diabetes. The most common infectious anaerobic agents are Gram-negative bacilli belonging to the Bacteroides/Parabacteroides, which under normal conditions constitute the natural human microflora. An important factor in the virulency of B. fragilis is the ability to form abscesses; a limited infection may progress to bacteraemia and then systemic inflammatory response syndrome and sepsis. Anaerobic bacteraemia mainly affects adults, with elderly patients over 65 years with underlying diseases. The importance of anaerobic bacteria in neonatal bacteraemia and sepsis is a relatively new phenomenon. In contrast the prevalence of anaerobes in bloodstream infections in children is extremely rare with children between 2 and 6 years of age having the least risk ranging 0–0.5% overall. The incidence of recovery of anaerobes in neonatal bacteraemia varies between 1.8% and 12.5%. The majority of cases reported in the literature were due to Bacteroides spp. (41%) other cultured anaerobes belonged to Clostridium spp. (32%), Peptostreptococcus spp. (20%).

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Urinary tract infections (UTIs) remain the most common infections diagnosed in outpatients and hospitalized patients. This study was designed to determine the patterns of antibiotic resistance and the prevalence of uropathogens causing UTIs in pediatric patients hospitalized between 1 January 2020 and 31 December 2022 at Teaching Hospital in Warsaw. The most frequent species isolated from urine samples were E. coli (64.5%), Klebsiella spp. (11.6%), and Enterococcus spp. (6.1%). UTIs caused by Enterobacter spp., Enterococcus spp., and Klebsiella spp. were significantly more common in children younger than three months of age than in children older than three months (p < 0.001). Trimethoprim and trimethoprim–sulfamethoxazole were the least active compounds against Enterobacterales with the resistance of E. coli, Klebsiella spp., P. mirabilis, and Enterobacter spp. in the range of 26.7/25.2%, 48.4/40.4%, 51.1/40.4%, and 15.8/13.2% respectively. Ampicillin was also found to have resistance rates for E. coli of 54.9% and P. mirabilis of 44.7%. Cefalexin and cefuroxime were highly active towards Enterobacterales except for Klebsiella spp., in which the resistance level reached 40%. Regarding third- and fourth- generation cephalosporins, resistance in E. coli and P. mirabilis was observed in approximately 2–10% of the isolates, but in Klebsiella spp. and Enterobacter spp. ranged over 30%. The resistance of Enterobacterales to carbapenems, nitrofurantoin, and fosfomycin was below 1%. The quinolones resistance was very high for Klebsiella spp. (31.1%) and P. mirabilis (29.8%) and three times lower for E. coli (11.9%), P. aeruginosa (9.3%), Enterobacter spp. (2.6%), and E. faecalis (4.6%). Resistance to multiple antibiotic classes was identified in 396 Enterobacterales strains, 394 of which were multi-drug resistant (MDR) and 2 were extensive drug-resistant (XDR). In the case of E. coli, 30% of isolates were MDR, with the proportion of strains having this exact resistance pattern similar in all of the analyzed years; no E. coli XDR strains were isolated. The number of Klebsiella spp. MDR strains was much higher in 2022 (60%) than in 2021 (47.5%). In the analyzed time, only one strain of K. pneumonia XDR, producing New Delhi metallo-β-lactamase, was isolated. Monitoring infection trends is essential to improve control and limit the rise of bacterial resistance. [ABSTRACT FROM AUTHOR]

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Copyright of Epidemiological Review / Przegląd Epidemiologiczny is the property of National Institute of Public Health - National Institute of Hygiene and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Staphylococcus aureus is bacteria that colonises the skin of about 30-40% of healthy humans. Methicillin-resistant S. aureus has been the most important cause of healthcare-associated infections worldwide and it is still the most commonly identified antimicrobial-resistant pathogen in hospitals all over the world. MRSA percentage in Poland, according to EARS-Net data is estimated on about 25%. To reduce the spread of MRSA, strategies targeting healthcare sectors should be applied. Important role in these proceeding should have microbiological screening of MRSA strain with application of molecular methods such as: PCR and real- time PCR. [ABSTRACT FROM AUTHOR]

Background: After the introduction of rotavirus vaccines into immunization schedules, noroviruses account for the majority of acute gastrointestinal infections. The aim of the study was to assess the clinical presentation in immunocompromised and immunocompetent children with hospital- and community-acquired norovirus gastroenteritis., Material and Methods: We retrospectively reviewed clinical records of children with noroviral gastroenteritis, hospitalized in the Pediatric Hospital, Medical University of Warsaw, between 2015 and 2018. Acute gastrointestinal tract symptoms and confirmed etiology of noroviral infection were inclusion criteria. The analysis was performed in the subgroups of immunocompetent and immunocompromised patients, during community-acquired and nosocomial infections., Results: A total of 57 children with median age 1.5 year (IQR: 0.7-4.0) were recruited. The majority of patients were immunocompetent (87.7%), and nosocomial infections were predominant (56.1%). Gastrointestinal symptoms included nausea, vomiting and diarrhoea (in approximately 85%), while systemic manifestations such as fever and malaise where observed in only ¼. Routine laboratory tests were normal in most of the patients. An analysis in the subgroups revealed statistically significant differences in blood pH and serum electrolyte levels - acidosis and electrolyte disturbances were statistically significantly more common in immunocompromised vs immunocompetent patients (p<0.05)., Conclusions: More frequently the clinical presentation includes gastrointestinal symptoms with no differences between immunocompromised and immunocompetent hosts. The median laboratory values were normal in generally healthy children; disturbances were observed only in children with immunodeficiencies. Therefore, prophylactic measures are of particular importance in the latter group, which is especially sensitive to severe and nosocomial infections., (© National Institute of Public Health – National Institute of Hygiene.)

Background: Diarrhea-associated hemolytic uremic syndrome (HUS D+) caused by verotoxigenic E. coli strains (VTEC) is a major cause of acute kidney injury in children between 1 and 5 years of age. Because of the short presence of VTEC in the gastrointestinal tract as well as difficulties with the detection of the verotoxigenic strain, identification of HUS etiology might be challenging., Objectives: The aim of the study was to assess the clinical and diagnostic value of serological tests for specific antibodies against verotoxigenic strains of E. coli in patients with HUS., Material and Methods: Eight children aged 8 months - 7.1 years (mean 40 ± 29 months) with symptoms of acute kidney injury, hemolytic anemia and thrombocytopenia observed after hemorrhagic diarrhea were included to the study. VTEC presence was detected in a stool culture with subsequent analysis of the ability to produce verotoxin and the presence of VT1 and VT2 as well as intimin and enterohemolysin genes. In addition, the presence of specific IgA, IgM and IgG antibodies against E. coli serogroups O26, O103, O104, O111, O121, O145 and O157 was measured using ELISA., Results: In 3 subjects, VTEC O26, O157 and O104 serogroups were cultured in the stool and the specific IgA, IgM and IgG antibodies were detected. In 4 subjects, no VTEC strains were cultured, however, high titers of IgA, IgM and IgG antibodies against E. coli O26, O157 and O111 were detected. In a single patient, the negative results of bacteriological and serological analyses excluded VTEC etiology of HUS., Conclusions: A serological analysis of VTEC can confirm the result of stool culture for verotoxigenic E. coli strains and help to find the cause of HUS in case of negative results of a stool culture.

Introduction: Number of infection caused by Clostridium difficile in hospitalized children is increasing. Even though children unlike adults seldom develop complications after being ill, cases of persistent diarrhoea triggered by this pathogen and mortality from this origin have been reported. At present the important problem constitute differentiation between the colonization and infection limiting the proper diagnosis of C. difficile infections (CDI) in this age group. The aim of this study was to evaluate the presence of lactoferrin in faeces as the inflammatory marker confirming C. difficile infections in children., Methods: Seventy seven samples of faeces where examined. Among them in 55 toxin A/B or C. difficile toxinogenic strain and in 15 nontoxinogenic C. difficile had been detected, 7 were collected from healthy children. Stool samples were tested with the use of method routinely applied in laboratory: automatic VIDAS C. difficile Toxin A&B test (bioMerieux, France), culture and GDH test. Lactoferrin in stool has been identified with ELISA IBD-SCAN test (Techlab, Blacksburg, VA). The CRP protein was detected with VITROS 5600., Results: Among 55 children with CDI lactoferrin was detected in 45,5% (25/55) of them. In 30 (54,5%) CDI patients the inflammatory biomarker was not identified. In 15 persons with nontoxinogenic strain cultured, one child had lactoferrin present. CDI was detected most frequently (51%) in 6-11 years old children. The increase of CDI cases was observed in period 2013-2014. Neither differences in frequency of raised CRP level in examined groups of children nor correlation between presence of lactoferrin and CRP was observed., Conclusions: Lactoferrin an intestinal inflammatory biomarker may be a useful tool in distinguishing between C. difficile infection and colonization. More studies including clinical observations are needed.

The presence of antibodies to Rickettsia conorii, R. helvetica, R. felis, R. slovaca, R. sibirica, and R. massiliae in sera of 129 forest workers from northeastern and southern Poland was assayed by indirect immunofluorescence. Previous environmental studies revealed presence of spotted fever group (SFG) rickettsiae in ticks collected from these areas. Additionally, the workers were examinated for the presence of antibodies specific to other tick-borne bacteria: Anaplasma phagocytophilum, Bartonella spp., and B. burgdorferi. The results of the studies have shown the presence of specific SFG rickettsiae antibodies in 14.7% of tested forest workers, among them 78.9% had species-specific antibodies to R. massiliae. Contrary to previous detection R. helvetica and R. slovaca in ticks collected in the environment of the examined area, no species-specific antibodies to these species were detected in studied workers. Antibodies to B. burgdorferi (44%) were found in forest workers more often than antibodies to other tested pathogens. B. burgdorferi was also the main component of coinfections. The most frequent confirmed serologically coinfections were simultaneous infections with B. burgdorferi and Bartonella spp. found in 10% of tested individuals. So far, SFG rickettsiae infections have not been diagnosed in Poland; however, the presence of the bacteria in ticks and presence of specific antibodies in humans exposed to arthropods show the need for monitoring the situation. The list of tick-borne pathogens is increasing, but knowledge about the possibility of humans acquiring multipathogens infections after tick bite still needs evaluation.

Shiga toxin-producing E. coli O157 and non-O157 are important emergance pathogens that can cause diarrhea and hemorrhagic colitis with life-threatening complications, such as hemolytic uremic syndrome (HUS). A few cases of EHEC infections are documented per year in Poland. Among them only one patient with EHEC O157 infection developed HUS. We characterized the first VTEC non-O157 strain isolated from child with HUS in Poland. The VTEC O111 strain produced Stx2 which was cytotoxic for Vero cell. Using DNA microarray analysis we have found set of virulence genes in VTEC O111 strain as: stx2A, stx2B, ehly, eae, tir tccP espA, espJ, cif nleA, nleB, lpfA, iha, efa1, cba. The strain was fenotypic resistant to streptomycin, tetracyclin and sulphonamides (strA, tetA, sul2 genes were detected).

Bartonella infections including cat scratch disease (CSD) is a group of infectious diseases which are diagnosed sporadically. Because of this fact the number of CSD cases in Poland is underestimated and their incidence is markedly lower in comparison to other European countries. The aim of our report is to present various diagnostic methods and possibilities on the basis of two cases with symptoms of CSD. The efficiency of specific Bartonella antibiotic therapy is also discussed.

Bartonella spp. bacteria are significant human pathogens and the agents of bacterial zoonosis acquired from an animal companion. The aim of the study was to determine the seroprevalence of two of the most common Bartonella species B. henselae and B. quintana in various human populations. The studied groups included: alcoholics, intravenous drug users, veterinarians, cats' owners. Blood samples were collected and cultured on chocolate agar plates and in mouse fibroblasts L-929 cell line culture. The levels of Bartonella henselae IgM and IgG antibodies were determined by indirect immunofluorescence assay. Specific B. henselae IgG were detected in 48.3% of homeless alcoholics, in 45.0% veterinarians and in 53.3% cats' owners. The differences in the prevalence of B. henselae antibodies between the studied groups and a control group were statistically supported. No homeless intravenous drug users had specific B. henselae and B. quintana antibodies. High titers of B. quintana IgG antibodies were detected in two homeless alcoholics. Bartonella spp. was cultured on chocolate blood agar plates from blood samples from 2 alcoholics. The isolates were identified as B. henselae by PCR amplification of the riboflavin synthase gene (ribC). The results prove that B. henselae and B. quintana, emerging human pathogens, are present and widely distributed in Poland in such specific risk groups as: alcoholics, veterinarians and cats' owners.

Background and Purpose: The aim of this study was to assess the correlation between morphological markers of carotid atherosclerosis, such as intima-media thickness (IMT) and the cross-sectional plaque area with markers of inflammation and C. pneumoniae infection., Material and Methods: The study involved a group of 128 persons (63 females, 49.2%), including 54 atherothrombotic stroke patients. The IMT and cross-sectional plaque area of common and internal carotid arteries were measured by ultrasonography. We assessed the C-reactive protein (CRP) and fibrinogen blood level, white blood cell (WBC) count, levels of IgA and IgG antibodies against C. pneumoniae , additionally the presence of C. pneumoniae DNA in WBCs was detected by PCR. We also considered the following risk factors: hypertension, diabetes, obesity and smoking., Results: The multiple regression analysis showed the strongest and independent correlations of WBC with the IMT (r=0.32; p=0.0003) and plaque area (r=0.24; p=0.008) increase. Also other factors, such as smoking (r=0.19; p=0.026), hypertension (r=0.18; p=0.023) and CRP concentration (r=0.17; p=0.036) showed a significant correlation with carotid IMT. C. pneumoniae -specific IgG antibodies level showed a significant correlation with IMT only in the linear regression analysis, but not in the multiple regression analysis. C. pneumoniae DNA presence results did not reveal a significant correlation with either IMT or the carotid plaque area., Conclusion: Inflammatory markers, especially the WBC count and CRP level, showed an independent and stronger correlation with carotid atherosclerosis than markers of C. pneumoniae infection.

Presence of specific IgM, IgG and IgA antibodies against Chlamydia pneumoniae was evaluated in children aged 1 week to 36 months to investigate the role of C. pneumoniae in respiratory infections and other diseases. Serum samples were obtained from 150 hospitalized children, including 123 children presenting the clinical symptoms of various respiratory tract infections, two children with acute diarrhoea, two children with meningitis, 14 children with urinary tract infection, and 9 children with non-infectious diseases. Levels of specific C. pneumoniae IgM, IgG and IgA serum antibodies were measured by enzyme-linked immunoassay (ELISA). C. pneumoniae IgM antibodies were detected in 16 (13.0 %) of 123 children with respiratory tract infections. Specific IgG antibodies were found in sera of 11 children under 12 months old. Among 27 children without symptoms of a respiratory tract disease, specific C. pneumoniae IgM were found in two (7.4%) children, including one child with meningitis and another child with urinary tract infection. Specific IgA antibodies were not found in any tested child. All cases of C. pneumoniae infections were identified within two calendar years out of eight that were analyzed, i.e. in 1997 and 2000. The incidence of C. pneumoniae infections varied seasonally, with most children infected in autumn. C. pneumoniae IgM antibodies were detected more often in girls (17.9%) then in boys (7.2%). C. pneumoniae infections occur among small children in central Poland. The results of this study indicate that C. pneumoniae may play a role in the etiology of respiratory tract infections in infants and young children.

Despite the growing number of scientific reports showing different markers of infection caused by Chlamydia pneumoniae in patients with advanced atherosclerosis, there is still no clear confirmation of a pathogenetic link between this infection and atherogenesis. The aim of the present study was to investigate the presence C. pneumoniae DNA in peripheral blood mononuclear cells and carotid endarterectomy samples obtained from patients with advanced atherosclerosis according to the presence specific antibodies against C. pneumoniae in serum. The levels of IgG, IgM and IgA antibodies to C. pneumoniae were determined by enzyme immunoassay (EIA) in sera of 36 patients with advanced atherosclerosis undergoing carotid endarterectomy. The presence of C. pneumoniae DNA in the carotid samples and in peripheral blood mononuclear cells was investigated by a nested polymerase chain reaction (PCR). We have not confirm the presence of C. pneumoniae DNA either in the carotid endarterectomy samples or in peripheral blood mononuclear cells, both in patients having the specific antibodies against C. pneumoniae and in seronegative patients. In the studied group of patients with advanced carotid atherosclerosis there was no correlation between the presence of specific antibodies against C. pneumoniae and the presence of C. pneumoniae DNA in endarterectomy samples and peripheral blood mononuclear cells.

To investigate the role of B. henselae in patients with symptoms suggesting neuroborreliosis, serum and cerebrospinal fluid samples were tested with serological and PCR methods. Among 17 examined patients, in 12 cases Borrelia burgdorferi infections were detected, in 1 case Bartonella henselae infection was ascertained, and in two patients mixed B. burgdorferi and B. henselae infections were found. These results indicate that mixed infections should be taken into consideration in establishing diagnosis of neurological disorders. Further study of this conclusion is needed.