Bertil Kaijser

A large Escherichia coli O157 outbreak in Sweden associated with locally produced lettuce.

In 2005 a large outbreak of verotoxin-producing Escherichia coli (VTEC) occurred in Sweden. Cases were interviewed and cohort and case-control studies were conducted. Microbiological investigations were performed using polymerase chain reaction (PCR) to detect the Shiga-like toxin (Stx) genes followed by cultivation and pulsed-field gel electrophoresis. A total of 135 cases were recorded, including 11 cases of hemolytic uremic syndrome. The epidemiological investigations implicated lettuce as the most likely source of the outbreak, with an OR of 13.0 (CI 2.94-57.5) in the case-control study. The lettuce was irrigated by water from a small stream, and water samples were positive for Stx 2 by PCR. The identical VTEC O157 Stx 2 positive strain was isolated from the cases and in cattle at a farm upstream from the irrigation point. An active surveillance and reporting system was crucial and cooperation between all involved parties was essential for quickly identifying the cause of this outbreak. Handling of fresh greens from farm to table must be improved to minimize the risk of contamination.

Enterohemorrhagic Escherichia coli (EHEC)

Enterohaemorrhagic Escherichia coli has since the last 2 decades been known to cause severe and bloody diarrhoea as well as haemorrhagic colitis (HC) and haemorrhagic uraemic syndrome (HUS) especially among children. The importance of screening for EHEC among children and older patients with severe symptoms is apparent. Production of the verocytotoxins VT1 and VT2 are the main features of EHEC, and the VT types and mode of action during human infection is described. There are, however, other features adding to the pathogenicity. In this review we deal with the importance of properties such as fimbriae and adhesins as well as systems to meet the bacterial need for iron during infection. These factors are probably important for the establishment of EHEC in the gut and add to the bacterial virulence. It has now become evident that VT producing E. coli, irrespective of serogroup, might be human pathogens. We conclude that knowledge of the different possible virulence factors adds to the possibility of separating more virulent from less virulent isolates.

Invasive disease caused by Haemophilus influenzae in Sweden 1997–2009; evidence of increasing incidence and clinical burden of non‐type b strains

Introduction of a conjugated vaccine against encapsulated Haemophilus influenzae type b (Hib) has led to a dramatic reduction of invasive Hib disease. However, an increasing incidence of invasive disease by H. influenzae non-type b has recently been reported. Non-type b strains have been suggested to be opportunists in an invasive context, but information on clinical consequences and related medical conditions is scarce. In this retrospective study, all H. influenzae isolates (n = 410) from blood and cerebrospinal fluid in three metropolitan Swedish regions between 1997 and 2009 from a population of approximately 3 million individuals were identified. All available isolates were serotyped by PCR (n = 250). We observed a statistically significant increase in the incidence of invasive H. influenzae disease, ascribed to non-typeable H. influenzae (NTHi) and encapsulated strains type f (Hif) in mainly individuals >60 years of age. The medical reports from a subset of 136 cases of invasive Haemophilus disease revealed that 48% of invasive NTHi cases and 59% of invasive Hif cases, respectively, met the criteria of severe sepsis or septic shock according to the ACCP/SCCM classification of sepsis grading. One-fifth of invasive NTHi cases and more than one-third of invasive Hif cases were admitted to intensive care units. Only 37% of patients with invasive non-type b disease had evidence of immunocompromise, of which conditions related to impaired humoral immunity was the most common. The clinical burden of invasive non-type b H. influenzae disease, measured as days of hospitalization/100 000 individuals at risk and year, increased significantly throughout the study period.

Inhibited growth of common enteropathogenic bacteria in lactic-fermented cereal gruels.

A natural lactic fermentation of mixtures of water and whole flour of either maize or high-tannin sorghum was obtained either before or after cooking to a weaning gruel: The preparations had a final pH of about 3.8 (range 3.67 to 4.00) and a ratio of lactic acid to acetic acid of 9∶1 (w/w). The growth of added (about 107 c.f.u./g gruel) Gram-negative intestinal pathogenic bacteria, enterotoxigenicEscherichia coli, Campylobacter jejuni, Shigella flexneri andSalmonella typhimurium, was strongly inhibited in the sour gruels, and the effect could primarily be explained by the low pH caused by the formation of lactic and acetic acids during the fermentation process. Of the added Gram-positive bacteria,Bacillus cereus andStaphylococcus aureus showed similar inhibited growth up to 7h after inoculation in the sour gruels. The strain ofStaphylococcus, however, showed only a continued reduction in growth in the fermented gruel samples, which had a viable lactic bacteria culture indicating the presence of a bacteriocin. This implies that a low pH (< 4.0) alone is not sufficient to sustain the inhibition of the growth ofStaphylococcus aureus. The survival studies were carried out at optimal temperatures for each respective enteropathogen.

Campylobacter upsaliensis, C. sputorum sputorum and C. concisus as Common Causes of Diarrhoea in Swedish Children

It has recently been reported that Campylobacter sp. other than Campylobacter jejuni/coli are likely to be the cause of gastroenteritis in humans. Examples are C. upsaliensis, C. jejuni doylei, C. concisus, C. lari and C. mucosalis (1–4).

Campylobacter jejuni/coli.

Historical background Campylobacter bacteria have, under other names, been known since the beginning of the century. In 1918 Smith reported on infectious abortion in cattle in relation to appearance of a bacterium denominated Spirilla (Smith 19 18). He and Taylor also called the bacterium Vibrio fetus (Smith & Taylor 19 19). Some years later Jones et al. ( 193 1) described enterocolitis in calves caused by a bacterium called Vibrio jejuni. In the 40’s Doylereported enterocolitis in swine (Doyle 1944). He named the infecting bacteria Vibrio coli. One of the first reports on human infections caused by Campylobacter was published 1946 by Levy (1946). The name “related Vibrios” was introduced by King in the end of the 50’s (King 1957). She found bacteria in blood cultures from patients with enterocolitis. It was not until 1963 that the genus Campylobacter (the name means curved rod) was introduced by Sebald & Veron (1963). They based their differentiation of this genus from Vibrio on the guanine/cytosine ratio on DNA. The fairly uncommon conditions for optimal growth of the bacteria, microaerophilic atmosphere and 42 “C, has apparently contributed to the late recognition of Campylobacter as a common cause of diarrhea. In 1972, it was possible for Dekeyser et al. to isolate Campylobacter jejuni from stools from two patients with enterocolitis by using a Millipore filter technique in combination with selective medium (Dekeyser et al. 1972). The same technique was utilized by Butzler et al. ( 1973) showing a high frequency of Campylobacter in children, as well as adults with acute enterocolitis. However, it was not until 1977 when Skirrow published his simple culture technique clearly showing the relation between Campylobacter and enterocolitis in humans, that the research activity on Campylobacter infections exploded (Skirrow 1977). In a few years reports from different geographical areas showed that Campylobacter jejuni/coli is one of the most common causes of human diarrhea in all parts of the world.

Complement activation and hematologic, hemodynamic, and respiratory reactions early after soft-tissue injury.

The effect of soft-tissue trauma was studied in dogs. Following injuries to the hind leg an aggregation of thrombocytes in blood and trapping in the lung was noted. Injury was initially followed by leukopenia and later by leukocytosis. Early hemolysis of red cells was observed. The injury was accompanied by complement activation. Its possible relation to hemolysis, leukopenia, thrombocytopenia, and increased insufflation pressure is discussed.

Flies and water as reservoirs for bacterial enteropathogens in urban and rural areas in and around Lahore, Pakistan

The study was conducted to isolate and characterize campylobacter, enterotoxigenic Escherichia coli-labile toxin (ETEC-LT), shigella and salmonella in flies and water. The material for the study, flies (n = 300) and water samples (n = 148), was collected from different localities in and around Lahore, Pakistan. Cultivation of the samples was performed on conventional standard media. Membrane filtration technique was used for water prior to culture. Determination of ETEC-LT was done by GM1 ELISA. Results of our study showed that flies and water were reservoirs for all the four pathogens, campylobacter, ETEC-LT, shigella and salmonella. Flies from the village were carrying fewer enteropathogens, while water from the village was found to be more contaminated as compared to the city. Campylobacter and ETEC-LT were the most frequently isolated pathogens in both flies and water. Thus the incidence of diarrhoeal disease in children of developing countries may be decreased by providing plenty of safe drinking water, improving excreta disposal, toilet facilities and giving education in personal hygiene.

Genetic Profiling of Enterohemorrhagic Escherichia coli Strains in Relation to Clonality and Clinical Signs of Infection

ABSTRACT Sixty-seven human strains of enterohemorrhagic Escherichia coli (EHEC) (from patients with more or less severe symptoms) were serogrouped and arranged according to pulsed-field gel electrophoresis (PFGE) patterns. We used PCR to investigate the strains according to known or putative virulence factors, and associations with disease were studied. All EHEC strains with the same PFGE pattern belonged to the same serogroup. On the contrary, two serogroups (O157 and O8) included strains with different PFGE patterns. We found several different combinations of chromosomal and plasmid-borne determinants, encoding the putative virulence factors, among the strains. As judged from clinical symptoms, there was no marked difference in pathogenicity among the strains and their combinations of virulence traits. All strains of O157 had the genes coding for verocytotoxin (VT) 2, intimin (eaeA), E. coli hemolysin (E-hly), and secreted serine protease (espP). Among EHEC non-O157 strains, the genes coding for VT1 and VT2 were equally dispersed. EaeA positivity was just as common among VT1- as VT2-positive strains. Among the plasmid-borne determinants, E-hly and espP were the most common and E-hly might be a pathogenicity marker among EHEC non-O157 strains. The conclusion is that PFGE is a very useful tool in epidemiological studies. The EHEC plasmids are heterogeneous in their gene composition, with the four plasmid-borne determinants found in many combinations. There was no reliable correlation between chromosomal and plasmid-borne virulence factors and human disease.

EHEC outbreak among staff at a children's hospital--use of PCR for verocytotoxin detection and PFGE for epidemiological investigation.

This is the first report of a major foodborne outbreak of enterohaemorrhagic Escherichia coli (EHEC) in Sweden. It occurred among the nursing staff at a childrens hospital with approximately 1600 employees. Contaminated lettuce was the most likely source of infection. Nine persons were culture-positive for Escherichia coli (E. coli) O157 and verocytotoxin-positive by PCR and a further two were verocytotoxin-positive by PCR only. All 11 EHEC-positive individuals had attended a party for approximately 250 staff members, which was held at the hospital. In a questionnaire 37 persons stated that they had symptoms consistent with EHEC infection during the weeks after the party. There was no evidence of secondary transmission from staff to patients. The value of PCR as a sensitive and fast method for diagnosis is discussed in this paper. Pulsed-field gel electrophoresis (PFGE) was used to ascertain that staff members were infected by the same clone, and that two patients with E. coli O157 infection were not.