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S Aleksic

Publications and source records attributed to S Aleksic.

At least 19 recordsLinked to original sources
PubMed1996

Prevalence and clinical manifestations of Shiga toxin-producing Escherichia coli infections in Austrian children.

The prevalence and clinical manifestations of infections associated with Shiga toxin-producing Escherichia coli (STEC) among Austrian children were assessed. Stool samples from 280 pediatric patients were analyzed by enzyme immunoassay (EIA) for the presence of free fecal Shiga toxin (Stx) 1 and 2, and by culture on sorbitol MacConkey agar. Specimens testing positive by the EIA were subjected to a cytotoxicity assay, polymerase chain reaction analysis, and a colony hybridization test. Direct culture on MacConkey agar demonstrated the presence of three Escherichia coli O157:H7-positive stools. These were also positive by EIA and by the DNA-based methods. An additional six samples were positive by EIA, and in four of these, non-O157 STEC of serotypes O111H-, O146:H-, and O113:H53 could be isolated. Analysis of stools for a variety of enteric pathogens demonstrated that STEC was the third most common bacterial pathogen. The clinical manifestations of STEC infections were difficult to distinguish from those of infections caused by other enteric pathogens, as most patients presented with watery diarrhea. The median age of children with STEC infections was 27.6 months (range, 7 months to 5.75 years); children with Salmonella or Campylobacter infections were younger on average, while those with Rotavirus infections were older. This study demonstrated that although Escherichia coli O157:H7 could be identified with the same sensitivity by both EIA or agar-based methods, the identification of non-O157 STEC strains was enhanced by the use of EIA followed by colony hybridization. Analysis of overnight cultures from 53 STEC isolates revealed that all strains producing Stx1, Stx2, or Stx2c reacted in the EIA. However, culture supernatants from Stx2e-producing Escherichia coli O101 were negative in the EIA. Despite this disadvantage, the EIA is easy to perform and time efficient and can be recommended as a screening test for non-O157 STEC in children with diarrhea.

Age Factors↗
PubMed1996

Diarrhea in young children associated with Escherichia coli non-O157 organisms that produce Shiga-like toxin.

OBJECTIVE: To assess the clinical manifestations and incidence of infection associated with Shiga-like toxin-producing Escherichia coli (SLTEC). STUDY DESIGN: Children with diarrhea within a defined geographic area during a 12-month period were examined for the presence of SLTEC in their stools by polymerase chain reaction with the use of primers that were complementary to sequences of Shiga-like toxins types I and II and to other virulence factors. RESULTS: There were 13 SLTEC infections among 468 children with diarrhea. Besides Shiga-like toxin sequences, the virulence genes eae and EHEC-hly were found in 10 isolates; these isolates were categorized as enterohemorrhagic E. coli (EHEC). Only 2 of 13 isolates were of the O157 strain. All reported cases occurred in summer (June through September) with the exception of one case in April. The infections were sporadic, and the infected children lived in rural and urban areas. Three infections in children with disabilities were hospital acquired. The majority of children had watery diarrhea, two had bloody diarrhea, and one had mild hemolytic-uremic syndrome. The overall incidence of SLTEC infection was 12.5 hospitalized children per 100,000 children less than 16 years of age. CONCLUSIONS: The most frequent clinical manifestation of SLTEC infection was watery diarrhea indistinguishable from other forms of infectious diarrhea. The shift from the O157 strain toward non-O157 SLTEC strains associated with diarrhea, also observed in German patients with hemolytic-uremic syndrome, points to a change in the epidemiologic features of SLTEC-associated disease. Testing for non-O157 SLTEC should be considered in children with diarrhea without a recognized cause.

Bacterial Toxins↗
PubMed1996

Human infection caused by Salmonellae of subspecies II to VI in Germany, 1977-1992.

Human infections by Salmonella (S.) are usually caused by S. enterica strains belonging to the subspecies I (subsp.). Strains of subsp. II-VI and S. bongori are mostly isolated from animals or environmental specimens, and they are therefore considered as less pathogenic for humans. Out of 90,201 S. isolates examined at the German National Reference Centre for Enteric Pathogens between 1977 to 1992, 89,798 (99.55%) belonged to S. subsp. I, while 403 (0.45%) of strains belonged to S. subsp. II-VI and S. bongori (formerly called subsp. V). 108 strains belonged to subsp. II, 241 isolates to subsp. IIIa and IIIb (formerly called Arizona), 49 to subsp. IV, 4 to S. bongori and one isolate to subsp. VI. 215 of the 403 isolates (53.4%) were from humans, 101 (25.1%) from reptiles, 52 (12.9%) from various warm-blooded animals, 11 (2.7%) from foodstuffs and 12 (3.0%) from environmental specimens. The origin of 12 (3.0%) strains was unknown. According to the clinical diagnosis reported by the laboratories, intestinal disease was associated with 176 (81.9%) out of 215 strains of human origin. 11 (5.1%) strains had been isolated from extraintestinal infections (sepsis, atypical pneumonia, urinary tract and wound infections), and 28 (13.0%) strains from stool specimens of healthy persons. A slightly higher incidence was observed in children of 0-5 years of age (49 cases; 22.8%). Male persons were twice as often affected than females. The seasonal incidence of infections was highest in October and in February. In 53 cases (24.6%), travel to a foreign country was reported.

Biological Specimen Banks↗
PubMed1996

Campylobacter and Salmonella contaminating fresh chicken meat.

1853 packages of fresh chicken breast meat of German, Dutch and French origin were investigated for their contamination with Campylobacter and/or Salmonella. Swabs were taken and cultured from dripwater, meat surface, meat interior and packet bowl. Campylobacter was isolated from 619 meat samples (= 33%), Salmonella from 377 meat packages (= 20%). In 111 of these contaminated chicken samples, both Salmonella and Campylobacter were present. The contamination rate and the species spectrum observed differed depending on the origin of the packages and the time of control.

Animals↗
PubMed1996

Isolation of enterohemorrhagic Escherichia coli O157 strains from patients with hemolytic-uremic syndrome by using immunomagnetic separation, DNA-based methods, and direct culture.

We examined 30 children with classical hemolytic-uremic syndrome (HUS) for the presence of enterohemorrhagic Escherichia coli (EHEC) strains in stool samples and determined the specific immune response to O157 lipopolysaccharide in acute-phase serum samples from these patients. EHEC O157 strains were isolated from stool samples of 18 (60%) of the patients, and non-O157 EHEC strains were isolated from 5 (17%) of the patients. For O157 strain isolation from stools, we introduced a selective enrichment step using O157-specific antibodies attached to paramagnetic particles (immunomagnetic separation [IMS] method). This procedure allowed the detection of O157 strains at 10(2) CFU/g of stool in the presence of 10(7) coliform background flora organisms. By using IMS followed by plating on sorbitol MacConkey (SMAC) agar and cefixime-tellurite SMAC (CT-SMAC) agar, O157 strains were detected in 18 samples, whereas colony hybridization detected a subset of 12 positive samples and direct culture on CT-SMAC or SMAC agar detected only 7. Three of the 18 O157-positive stools were negative by cytotoxicity assay performed with stool filtrates and by direct PCR with DNA extracted from stools. The IMS technique allowed the isolation of O157 strains from 18 of 20 patients with serological evidence for O157 infection. Apart from the increase in sensitivity in O157 detection compared with that of direct culture, the IMS technique also has the advantage of being less labor-intensive and less time-consuming than the molecular methods. IMS can therefore be considered an efficient method for wide-spread use in the detection of O157 strains in clinical microbiology laboratories. However, because a significant number of HUS cases were attributable to non-O157 EHEC serogroups, the use of additional methods besides IMS in the bacteriological diagnosis of HUS is necessary.

Antibodies, Bacterial↗
PubMed1996

Cardiac autonomic nerve function and insulin sensitivity in obese subjects.

OBJECTIVE: To investigate whether obesity influences cardiac autonomic nerve function. DESIGN: Comparing two groups of subjects with different degrees of obesity to normal weight controls. SUBJECTS: 19 healthy controls (mean age 33 y, BMI 21.7 +/- 0.2 kg/m2) and 17 obese non-diabetic subjects (mean age 39 y, BMI 33.7 +/- 1.8 kg/m2). MEASUREMENTS: Insulin sensitivity was calculated by an oral glucose tolerance test. Autonomic nerve function was evaluated by analysing the variation of the heart frequency at rest (coefficient variation of R-R intervals, REST 1), during deep respiration, at a Valsalva maneuver (longest/shortest R-R interval during inspiration hold) and by the Ewing test (ratio between the 30th and 15th R-R interval after reaching up-right position). RESULTS: The obese showed a lower insulin sensitivity than healthy controls (3.09 vs 4.60 mg x l2/mmol x mU x min, P < 0.001). Their variation in heart frequency was reduced (REST 1: 1.95 vs 2.9, P < 0.01, Valsalva: 1.30 vs 1.52 and Ewing test: 1.03 vs 1.14, P < 0.05). However, patients with moderate (BMI 31.7 kg/m2) or severe obesity (39.0 kg/m2) with identical insulin sensitivity had no significant difference in autonomic nerve function. Except for the Ewing test all measured parameters for the evaluation of cardiac autonomic nerve function correlated with the degree of diminished insulin sensitivity (REST 1: r = 0.475, P < 0.001). CONCLUSION: Moderate obesity with significantly decreased insulin sensitivity is associated with impaired cardiac autonomic nerve function.

Adult↗
PubMed1995

Nationwide outbreak of human salmonellosis in Germany due to contaminated paprika and paprika-powdered potato chips.

Between April and September 1993, a nationwide outbreak of salmonellosis occurred in Germany which was traced to contaminated paprika and paprika-powdered potato chips. Of the estimated 1000 cases, children below 14 years were principally affected. Levels of 0.04-0.45 organisms per gram were found in the snacks. The infective dose was estimated at 4-45 organisms with an attack rate of 1 in 10,000 exposed persons. The unique feature of the outbreak was the variety of serovars involved. S. saintpaul, S. rubislaw and S. javiana were isolated during the same time period from paprika powder, spice mixtures, snacks and patients. Their clonal identity was confirmed by molecular typing methods. Furthermore, monophasic and non-motile strains of rare salmonella O-groups were isolated from both paprika products and patients. This is the largest documented outbreak due to contaminated spices which proved that even extremely low numbers of salmonellae adapted to the dry state were able to cause illness.

Adolescent↗
PubMed1995

Development of PCR for screening of enteroaggregative Escherichia coli.

In this study, we determined the sequence of the EcoRI-PstI fragment of the plasmid pCVD432, also termed the enteroaggregative Escherichia coli (EAggEC) probe. A primer pair complementary to this probe was designed for PCR amplification of a 630-bp region. Comparison of the analysis of the EAggEC probe sequence with those in database libraries revealed no significant similarity to any known bacterial gene. Pure cultures of E. coli cells, as well as mixed cultures from stool specimens, were investigated with the PCR assay, the EAggEC probe test, and the adherence test. Of 50 E. coli strains which demonstrated aggregative adherence to HEp-2 cells, 43 (86%) were positive with the EAggEC PCR. All 43 of these strains reacted with the EAggEC probe. Six EAggEC strains gave negative results by both molecular techniques. In contrast, only 4 of 418 (0.96%) strains representing other categories of diarrheagenic E. coli demonstrated a positive PCR result. The PCR was also successful in screening for the presence of EAggEC in enriched cultures grown from stool specimens. Compared with cell culture assays and colony hybridization, our findings revealed that the PCR assay was more rapid, simple, and highly sensitive and can therefore be recommended as a screening method for EAggEC in the clinical laboratory.

Adolescent↗
PubMed1994

Virulence factors and phenotypical traits of verotoxigenic strains of Escherichia coli isolated from human patients in Germany.

Fecal isolates of Escherichia coli which were collected from human patients in different parts of Germany between 1985 and 1992 were examined for production of verotoxins (VT). Among 2165 isolates 54 (2.5%) verotoxigenic E. coli (VTEC) were found. The 54 VTEC belonged to 13 different serotypes, 46 (85.2%) of these were enterohemorrhagic E. coli (EHEC) types as O157:H7, O157:H-, O145:H-, O111:[H8] and O26:[H11]. Of the 54 VTEC 50 (92.6%) hybridized with one or both of the DNA probes specific for VT1 and VT2. The 4 VTEC strains which were negative for VT1 and VT2 differed from all other VTEC by many phenotypical trains such as serotype, production of alpha-hemolysin and absence of EHEC-plasmid and "attaching and effacing" (eae)-specific DNA sequences. In contrast, VTEC which were positive for VT1, VT2 or both were frequently positive for eae sequences (92.0%), EHEC-plasmids (90.0%) and for production of enterohemolysin (88.0%). With enterohemolysin as an epidemiological marker more VTEC strains (81.5%) could be identified than with others such as the absence of beta-glucuronidase activity (61.1%) or non-fermentation of sorbitol (48.1%). Case reports were available for 42 of the 54 VTEC strains. The clinical presentation of 42 cases with VTEC ranged from uncomplicated diarrhea to severe diseases as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). However, bloody diarrhea, HC and HUS were more associated with the O157 group than with other VTEC groups.

Adult↗
PubMed1994

Prevalence of attaching and effacing Escherichia coli in stool samples from patients and controls.

Enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) have the ability to cause 'attaching and effacing' (AE) lesions; the genes necessary to cause AE in both of these pathogroups have been identified and termed eae. Using colony hybridization, we screened 237 stool samples from patients with diarrhea, and 237 stool samples from age-matched controls for the presence of E. coli carrying eae. Individual colonies harbouring eae could be recovered from 7 (2.9%) of the patient stools, as well as from 6 (2.5%) of the control stools. All these E. coli isolates were positive in the fluorescence actin staining (FAS) test. In addition, all the samples were also probed for Shiga-like toxin (slt) genes and the EPEC adherence factor (EAF) to evaluate whether testing for eae identified all EHEC and class I EPEC. Of the 7 patient samples harbouring E. coli with eae, 4 had E. coli with eae and slt genes, and 2 had E. coli with eae and EAF sequences. In 2 of the 237 patient stools, E. coli which were eae and EAF negative but slt probe positive could be recovered. These 2 E. coli strains were non-reactive in the FAS test. Of the control samples, none of the E. coli strains, including the 6 samples containing eae positive strains, possessed EAF or slt-sequences. In concrete terms, the similar eae incidence found in both E. coli isolates from patients and controls is currently of limited clinical diagnostic value and more importantly, the eae probe could not identify all slt-harbouring E. coli. On the basis of these results, the use of the eae-probe cannot be recommended in preference to the slt probes for the detection of EHEC.

Adhesins, Bacterial↗
PubMed1994

Characterisation of pathogenic Yersinia enterocolitica serogroups by pulsed-field gel electrophoresis of genomic NotI restriction fragments.

Enteropathogenic Yersinia enterocolitica is an important cause of human and animal disease. Phenotypic and genotypic characteristics currently used to identify Y. enterocolitica are not necessarily sufficient to differentiate pathogenic from non-pathogenic strains or to analyse the epidemiology of yersiniae at a molecular level. To improve the characterisation of Yersinia isolates, NotI restriction fragment length polymorphisms (RFLPs) of chromosomal DNA of more than 100 clinical, animal and environmental isolates were analysed in pulsed-field gel electrophoresis. Highly conserved RFLP patterns with fragments ranging from 15 to 400 kb were detected within each of 10 Y. enterocolitica serogroups tested. Determination of RFLP types makes it possible to discriminate between isolates of different Y. enterocolitica serogroups and other Yersinia spp. Moreover, NotI restriction endonuclease analysis allows even subtyping of strains belonging to a unique serogroup-biotype. Identification of NotI fragments hybridising with inv- or ail-homologous sequences was used as an additional discriminating marker. The results indicate that NotI RFLP typing can provide a powerful new tool for the differentiation of clinical Y. enterocolitica isolates.

Animals↗
PubMed1993

Characterization of Yersinia pseudotuberculosis serogroups O9, O10 and O11; subdivision of O1 serogroup into O1a, O1b, and O1c subgroups.

In this study, three new antigens (O9, O10 and O11) of Yersinia pseudotuberculosis are described. The O1 antigen is further subdivided into O1a, O1b and O1c. The methods used to prepare specific antisera for O-antigen identification are also described. Furthermore, the H antigens of these new serogroups are determined and their biochemical characteristics analysed. The antigenic formulae of the known serogroups within the basic antigenic scheme introduced by the authors' laboratories are presented.

Antigenic Variation↗
PubMed1993

Clonal structure and pathogenicity of Shiga-like toxin-producing, sorbitol-fermenting Escherichia coli O157:H-.

We compared a collection of sorbitol-fermenting (SF) Escherichia coli O157:H- strains with SF E. coli O157:H45 and non-SF E. coli O157:H7 and E. coli O157:H- strains by pulsed-field gel electrophoresis. The SF E. coli O157:H- strains had identical or closely related XbaI patterns that differed markedly from those for the other E. coli O157 strains. Plasmid content and the presence of Shiga-like toxin-converting phages were determined for the SF E. coli O157:H- strains, indicating that these strains harbor a single 90-kb plasmid. They are lysogenized by toxin-converting phages and harbor the eae gene. Nonmotile E. coli O157 strains were observed to adhere more efficiently to HEp-2 cells than the motile strains. From their phenotypic and genotypic features, the SF E. coli O157:H- strains may well represent a new clone with non-SF E. coli O157:H7 pathogenic characteristics.

Bacterial Adhesion↗
PubMed1993

Differentiation of Yersinia enterocolitica serotype O:5,27 strains by phenotypic and molecular techniques.

Restriction endonuclease analyses of virulence plasmid DNA (REAP) and chromosomal DNA and other phenotypic characteristics were used to study the differentiation of Yersinia enterocolitica serotype O:5,27 strains. There was a close correlation between REAP patterns and the geographical distribution of serotype O:5,27. Human isolates produced only one REAP pattern, which was also found with isolates from pigs and dogs.

Animals↗
PubMed1993

[A comparison of BRILA-MUG and lauryl sulfate-MUG bouillon as detection media for total and fecal coliform bacteria in bathing waters in conformity with the Economic Community Guideline 76/160 EWG].

The spectrum of gram-negative rods occurring in surface waters is wide and depending on the season, i.e. the water temperature. The concentration of bacteria is higher in summer than in winter. However, the seasonal difference of the concentration of Enterobacteriaceae is less than that of the Aeromonas spec. and of the non-fermenters. The comparison of yields of total and faecal coliforms determined in samples of surface water by using the brilliant green bile lactose 4-methylumbelliferyl-beta-D-glucuronide (BRI-LA-MUG) broth and the lauryl sulfate-MUG broth, respectively, shows that the BRILA-MUG broth is more sensitive and gives higher yields than the lauryl sulfate-MUG broth. On the other hand, the lauryl sulfate-MUG broth inhibits more the growth of gram-negative rods, especially that of Aeromonas spec. and non-fermenters, whereas the Enterobacteriaceae are less inhibited.

Aeromonas↗
PubMed1992

Molecular detection of sorbitol-fermenting Escherichia coli O157 in patients with hemolytic-uremic syndrome.

Shiga-like toxin-producing Escherichia coli strains of serogroup O157 were identified in 26 of 104 patients with hemolytic-uremic syndrome and in 18 of 668 patients with diarrhea. All strains were identified by colony hybridization with DNA probes complementary to Shiga-like toxin I and Shiga-like toxin II gene sequences and characterized by biochemical tests and serotyping. Seventeen of these 44 patients had E. coli O157 strains which were unusual because they fermented sorbitol within 24 h of incubation and were positive for beta-glucuronidase activity. Culture filtrates of these sorbitol-fermenting strains were highly toxic to Vero cells in culture. Serological tests and DNA analysis performed by restriction endonuclease digestion of B-subunit toxin genes revealed that all 17 isolates produced Shiga-like toxin II. Although by using molecular probes we established a high frequency of sorbitol-fermenting E. coli O157 strains in the patients we examined, further studies on the prevalence of such isolates in other areas of endemic disease are clearly warranted.

Adolescent↗
PubMed1992

[Growth behavior of Enterobacteriaceae in BRILA-MUG-broth and in different modifications of broth].

Both substances, brilliant green and bile, inhibit the growth of gram-positive bacteria in culture media and selectively enrich gram-negative bacteria. Therefore, the brilliant green-lactose-bile broth (BRILA) and the BRLA broth supplemented with tryptophan and methyl-umbelliferyl-beta-D-glucuronide (BRILA-MUG) contain brilliant green as well as bile. Because BRILA-MUG broth as a selective enrichment and differentiating medium of faecal coliform and total coliform bacteria, E. coli and coliforms, respectively, is recommended for testing samples of surface water according to the EC guidelines for bathing waters (no. 76/160 EWG), the question arose of the optimal combination of components in the BRILA-MUG broth. As the described investigations show, the addition of buffer substances did not improve the culture properties of the BRILA-MUG broth. However, the original BRILA broth was improved by supplementing it with buffer substances such as CaCO3 or Na2HPO4. The same effect of culture improvement was obtained by removing brilliant green. This modification of BRILA broth is practically identic with the well-known MacConkey broth. On the other hand, the modification of omitting bile from the original BRILA broth causes a remarkable impairment of the culture properties lowering bacterial counts per ml by 3-5 log. The observations suggest that brilliant green inhibits both, gram-positive bacteria as well as the gram-negative Enterobacteriaceae. Therefore, it is a selective substance of doubtful usefulness.

Anti-Infective Agents, Local↗