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An enteroaggregative Verotoxin (Vtx)-producing Escherichia coli strain of serotype O104:H4 has recently been associated with an outbreak of haemolytic-uremic syndrome and bloody diarrhoea in humans mainly in Germany, but also in 14 other European countries, USA and Canada. This O104:H4 E. coli strain has often been described as an enterohaemorrhagic E. coli (EHEC), i.e. a Vtx-producing E. coli with attaching and effacing properties. Although both EHEC and the German O104:H4 E. coli strains indeed produce Vtx, they nevertheless differ in several other virulence traits, as well as in epidemiological characteristics. For instance, the primary sources and vehicles of typical EHEC infections in humans are ruminants, whereas no animal reservoir has been identified for enteroaggregative E. coli (EAggEC). The present article is introduced by a brief overview of the main characteristics of Vtx-producing E. coli and EAggEC. Thereafter, the O104:H4 E. coli outbreak is compared to typical EHEC outbreaks and the virulence factors and host specificity of EHEC and EAggEC are discussed. Finally, a renewed nomenclature of Vtx-producing E. coli is proposed to avoid more confusion in communication during future outbreaks and to replace the acronym EHEC that only refers to a clinical condition.

In September-October 2007, a mixed-serotype outbreak of verocytotoxin-producing Escherichia coli (VTEC) O145:H28 and O26:H11 occurred in the province of Antwerp, Belgium. Five girls aged between 2 and 11 years developed hemolytic uremic syndrome, and seven other coexposed persons with bloody diarrhea were identified. Laboratory confirmation of O145:H28 infection was obtained for three hemolytic uremic syndrome patients, one of whom was coinfected with O26:H11. The epidemiological and laboratory investigations revealed ice cream as the most likely source of the outbreak. The ice cream was produced at a local dairy farm using pasteurized milk. VTEC of both serotypes with indistinguishable pulsed-field gel electrophoresis patterns were isolated from patients, ice cream, and environmental samples. Quantitative analysis of the ice cream indicated concentrations of 2.4 and 0.03 CFU/g for VTEC O145 and O26, respectively. Virulence typing revealed that the repertoire of virulence genes carried by the O145:H28 outbreak strain was comparable to that of O157 VTEC and more exhaustive as compared to the O26:H11 outbreak strain and nonrelated clinical strains belonging to these serotypes. Taken together, these data suggest that O145:H28 played the most important role in this outbreak.

Objectives: To collect recent data on the susceptibility of anaerobes and to compare them with results from previous studies., Methods: Four hundred and forty-three anaerobic clinical isolates from various body sites were prospectively collected from October 2003 to February 2005 in nine Belgian hospitals. MICs were determined for nine anti-anaerobic and three recently developed antibiotics., Results: Most gram-negative bacilli except Fusobacterium spp. were resistant to penicillin. Piperacillin/tazobactam, metronidazole, chloramphenicol, meropenem and amoxicillin/clavulanic acid were very active against all groups, but only 86% of Bacteroides fragilis group strains were susceptible to the latter. Cefoxitin, cefotetan and clindamycin were less active. In particular, only 62%, 52% and 48% of B. fragilis group strains were susceptible, respectively. Clindamycin shows a continuing decrease in activity, as 83% were still susceptible in 1987 and 66% in 1993-94. Anti-anaerobic activity of the new antibiotics is interesting, with MIC50 and MIC90 of 1 and >32 mg/L for moxifloxacin, 2 and 4 mg/L for linezolid and 0.5 and 8 mg/L for tigecycline., Conclusions: The susceptibility of anaerobic bacteria remains stable in Belgium, except for clindamycin, which shows a continuous decrease in activity. However, for each of the tested antibiotics, at least a few resistant organisms were detected. Consequently, for severe infections involving anaerobic bacteria, it could be advisable to perform microbiological testing instead of relying on known susceptibility profiles. Periodically monitoring background susceptibility remains necessary to guide empirical therapy.

Background: Although the causative pneumococcal serotypes of invasive diseases are already extensively studied, few data are available about the pneumococcal serotypes additionally isolated from broncho-alveolar lavage samples in childhood pneumonia., Study Aim: To identify the causative pneumococcal serotypes in culture proven childhood community acquired pneumonia (CAP) and to calculate the effectiveness of the heptavalent and nonavalent pneumococcal vaccine (7- and 9-valent PnV) in severe pneumococcal pneumonia., Methods: All pneumococcal isolates stored from broncho-alveolar lavage, blood culture and pleural fluid in healthy children with CAP were characterized., Results: Seventy children (median age 2 years 3.5 months) could be included. The most prevalent serotypes were: SGT1 (21.4%), SGT6 (20.0%), SGT19 (12.8%), SGT23 (10.0%), and SGT14 (7.1%). SGT1 was especially prevalent in complicated cases and children >5 years. This first ranking of SGT1 is not reported in invasive pneumococcal disease studies. The overall theoretical coverage of the 7-valent PnV and the 9-valent PnV for pneumococcal pneumonia was 45.7% and 72.8%. The theoretical coverage of both vaccines was equal for non-invasive pneumonia (64%) but the theoretical coverage of the 9-valent PnV for invasive pneumonia was much higher (79% vs. 37.2%). Antibiotic susceptibility to penicillin was 84%, 70% to tetracycline and 61% to erythromycin; however only one strain (MIC = 4 mg/L) was highly resistant to penicillin., Conclusions: Based on this serotyping, the theoretical coverage of the 7-valent PnV for proven pneumococcal pneumonia is good but decreases with age. A 9-valent PnV containing SGT1 could significantly increase the coverage, especially for invasive pneumonia. According to these data, penicillin remains the first choice antibiotic treatment for childhood CAP in Belgium.

Neonatal immaturity of the immune system is currently believed to generally limit the induction of immune responses to vaccine Ags and to skew them toward type 2 responses. We demonstrated here that Bordetella pertussis infection in very young infants (median, 2 mo old) as well as the first administration of whole-cell pertussis vaccine induces B. pertussis Ag-specific IFN-gamma secretion by the PBMC of these infants. IFN-gamma was secreted by both CD4(+) and CD8(+) T lymphocytes, and the levels of Ag-induced IFN-gamma secretion did not correlate with the age of the infants. Appearance of the specific Th-1 cell-mediated immunity was accompanied by a general shift of the cytokine secretion profile of these infants toward a stronger Th1 profile, as evidenced by the response to a polyclonal stimulation. We conclude that the immune system of 2-mo-old infants is developmentally mature enough to develop Th1 responses in vivo upon infection by B. pertussis or vaccination with whole-cell pertussis vaccines.

OBJECTIVE: To evaluate the isolation rate of O157 and non-O157 verocytotoxin-producing Escherichia coli (VTEC) strains, to study the occurrence of additional virulence factors and to correlate these with clinical symptoms. METHODS: Over more than 5 years, 17 296 unduplicated fecal samples submitted for routine culture were screened for VTEC by a single PCR detecting VT1, VT2 and its variants. Verocytotoxin B subunit genotypes of the isolates obtained by testing individual colonies in positive samples were determined by a polymerase chain reaction---restriction fragment length polymorphism (PCR---RFLP) technique, the eaeA gene and the 60-MDa virulence plasmid by PCR, and the hemolytic phenotype by using CaCl2-washed blood agar. RESULTS: Verocytotoxin genes were found in 1.02% of the samples. Non-O157 VTEC strains were isolated in 0.66% and O157 in 0.17%. Overall, VTEC was less frequently isolated than Campylobacter and Salmonella but more frequently than Yersinia and Shigella. All cases except two siblings were epidemiologically unrelated. Cases of hemolytic uremic syndrome (HUS) were only observed in association with serogroup O157, which seems to be more pathogenic than the non-O157 strains. Among non-O157 VTEC strains, eaeA-positive strains are more frequently associated with clinical symptoms than are eaeA-negative strains. Other virulence factors correlate less closely with the presence of symptoms. CONCLUSIONS: VTEC is the third bacterial intestinal pathogen in our study population. All stool samples from patients with diarrhea should be screened for the most frequent serogroup, O157, or, if this is not possible, at least those from patients with bloody diarrhea. Non-O157 VTEC strains, especially if they are eaeA positive, are also associated with diarrhea, more often non-bloody. PCR or the new commercially available immunoassays could be used in selected cases, e.g. in patients suffering from HUS and in cases of outbreaks.