Yersinia enterocolitica surveillance in Belgium (1979-1989).
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Biomedical subjects
Publications and source records attributed to G Wauters.
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The gene encoding the heat-stable enterotoxin (yst) was cloned from the chromosome of Yersinia enterocolitica W1024 (serotype O:9), and the nucleotide sequence was determined. The yst gene encodes a 71-amino-acid polypeptide. The C-terminal 30 amino acids of the predicted protein exactly correspond to the amino acid sequence of the toxin extracted from culture supernatants (T. Takao, N. Tominaga, and Y. Shimonishi, Biochem. Biophys. Res. Commun. 125:845-851, 1984). The N-terminal 18 amino acids have the properties of a signal sequence. The central 22 residues are removed during or after the secretion process. This organization in three domains (Pre, Pro, and mature Yst) resembles that of the enterotoxin STa of Escherichia coli. The degree of conservation between the E. coli and Y. enterocolitica toxins is much lower in the Pre and the Pro domains than in the mature proteins. The mature toxin of Y. enterocolitica is much larger than that of E. coli, but the active domain appears to be highly conserved. The yst gene of Y. enterocolitica introduced in E. coli K-12 directed the secretion of an active toxin. The cloned yst gene was used as an epidemiological probe among a collection of 174 strains representative of all Yersinia species except Yersinia pestis and numerous Y. enterocolitica subgroups. In Y. enterocolitica, there was a clear-cut difference between pathogenic and nonpathogenic strains: 89 of 89 pathogenic and none of 51 nonpathogenic strains contained yst-homologous DNA, suggesting that Yst is involved in pathogenesis. Among the other Yersinia species, only four strains of Yersinia kristensenii had DNA homologous to yst.
Rabbit polyclonal antisera were raised against the pYV-encoded outer membrane protein P1 of five Yersinia enterocolitica strains belonging to serogroups O:3, O:5,27, O:8, and O:9. Analysis of these strains with the sera showed that P1 presented at least six different antigenic factors. Two of the serum specimens were chosen to test the P1 agglutinability of 797 strains isolated from various sources. This technique appeared to be more reliable than autoagglutination and Ca2+ dependency to monitor the presence of the pYV plasmid. Hence, we propose this P1-mediated agglutination as a new and easy virulence test.
Potential sources of Legionella spp. in a university hospital were investigated over 3 years in order to gain better understanding of the ecology and transmission of this organism to hospitalized patients. The survey highlighted the contamination of the hot water system with high concentrations of legionellas (up to 10(6) cfu 1(-1]. Legionella pneumophila serogroup 6 was predominant followed by L. pneumophila serogroup 10. Serogroup 1 and other species (L. longbeachae, L. micdadei) were rarely isolated. Serogroup 6 was also the predominant cause of nosocomial legionellosis in 15 sporadic cases in immunocompromised patients from 1981 to 1987. In light of this problem, several control measures were tried consecutively. A disinfection cycle with 6 ppm free chlorine failed to eradicate legionellas because of difficulties with the plumbing system. Raising the temperature in hot water tanks to 80 degrees C was effective locally, but mixer tanks where cold and hot water (60-65 degrees C) are mingled in order to achieve 45 degrees C became the principal reservoirs. Disconnecting the mixer tanks, maintaining a temperature of 60 degrees C in the heating tanks and accelerating the flow rate in the hot water system proved to be the most useful measures.
During the last week of May 1986, a 1-week prospective study on antibiotic utilization in surgical patients was held in 104 (42%) of the 247 Belgian acute care hospitals. All surgical patients with a post-operative stay of at least 3 days were studied, involving 3112 patients. Each patient was observed for 7 days, starting from the day before surgery. Antibiotics were administered to 71.9% of all patients; 21.9% received therapeutic antibiotics and 52.9% prophylactic antibiotics; 2.9% received both. Of the 1285 patients undergoing a surgical procedure with no indication for antimicrobial prophylaxis, 50.7% nevertheless received prophylaxis; 92.8% of patients with a generally recognized indication for prophylaxis received antibiotic prophylaxis. Less than one fifth (17.1%) of all prophylactic courses were stopped on the day of the intervention whilst 26.3% were continued up to the fifth post-operative day or beyond. The most frequently prescribed drugs for this indication included first and second generation cephalosporins and nitroimidazoles. The number of different generic drugs utilized per hospital ranged from 1 to 18 (mean: 7.7).
Recently, new beta-lactam antibiotics, such as imipenem/cilastatin (IMP) with an unusually broad antibacterial spectrum and especially an adequate P. aeruginosa activity, have introduced the possibility of using prospective agent as empiric management of febrile granulocytopenic patients. We randomized 83 febrile neutropenic cancer patients for a prospective evaluation of two regimens: IMP versus piperacillin plus amikacin (PA). Both patients groups were similarly distributed with regard to age, sex, primary diagnosis and degree of granulocytopenia. More than 20% of the 74 evaluable patients had bacteraemia. The overall response rate for clinically or microbiologically documented infections was 90% in the IMP regimen versus 76% in the PA regimen, but statistical difference was not achieved. All bacteraemias in the IMP group but only 60% in the PA group were cured, however statistical difference was not achieved. IMP had to be discontinued in only one patient and the most common side effects were nausea and vomiting; no seizures were noted. Nephro- and ototoxicity, skin rash and bleeding have been the major side effects requiring drug discontinuation in 6 patients treated by PA. In conclusion, these data suggest that IMP used alone is safe and as effective as the combination of P plus A for the management of febrile granulocytopenic patients with haematologic malignancies. Further studies on a larger number of patients are needed to confirm these findings.
Analysis of the electrophoretic profiles of the outer membrane proteins could be used to differentiate Campylobacter jejuni (16 strains) from Campylobacter coli (10 strains). This observation was confirmed by the study of DNA homology obtained by a quantitative filter hybridization method. The hippurate hydrolysis test gave a poor correlation with the results of differentiation obtained by DNA homology studies and outer membrane protein profile.
A new enrichment medium for the recovery of pathogenic Yersinia enterocolitica serogroup O:3 from naturally infected meat products based on three selective agents, Irgasan, ticarcillin, and potassium chlorate (ITC), was compared with several other one- or two-step enrichments. Y. enterocolitica serogroup O:3 was recovered from 96.5% of 29 pork tongues, 24% of 50 ground pork samples, 16% of 25 masseter muscle samples, and 61% of tonsils. ITC was by far the most sensitive method for the recovery of Y. enterocolitica O:3, especially from ground meat and masseter muscles, while cold and two-step enrichments yielded better results for nonpathogenic strains. Plating of ITC enrichments onto SS-deoxycholate-calcium agar gave overall better results than plating onto cefsulodin-Irgasan-novobiocin agar for serogroup O:3.
The intensive care units (ICU) constitute one of the sectors of the hospital with the highest incidence of infections. Part of the patients admitted to the ICU are carrier of an, often serious, infection which justified their admission. But more important are of infections contracted in the course of hospitalization. These are particularly frequent because of the principal factors which govern the emergence of nosocomial infections are present in the ICU in a very evident way. The frequency of infections which are essentially of the nosocomial type, compels the microbiology laboratory to adapt certain attitudes in the performance as well as in the interpretation of bacteriological analyses. The following points have to be dressed: the "colonisation" of various sites by potentially pathogenic bacteria should obviously be interpreted correctly; a systemic supervision sampling has become current in the ICU; the organization of the laboratory must allow a correlation of the results obtained from different samples; the laboratory must be accustomed to the bacterial ecology of the hospital and more specifically to this of the ICU; as the risk of nosocomial infections in the ICU is quite high, hospital hygiene and supervision of hospital strains are directly involved.
To determine the risk factors for Yersinia enterocolitica (YE) infection in Belgium, which is the country with the highest incidence of this infection, 40 persons with YE infections due to serotype O:3 (n = 36) or O:9 (n = 4) were compared with matched controls. Most patients had acute gastroenteritis; 1 had a liver abscess. 20% were admitted to hospital; the mean duration of hospital stay was 9 days. YE infection was strongly associated with eating raw pork in the 2 weeks before onset (odds ratio = 12, p = 0.00002), a factor that accounted for 58% of the YE infections studied. 14 (18%) of 79 families surveyed at a well-baby clinic fed their children raw pork from a median age of 18 months. Specific control measures to reduce contamination and consumption of raw pork may reduce the incidence of YE infections.
A total of 38 strains of Corynebacterium Group D2 isolated from clinical specimens in Belgian laboratories were characterized by pronounced urease activity, inability to acidify sugars and to reduce nitrates and multiresistance to antibiotics. Two strains were involved in clinical diseases. The organisms were found to have a more opportunistic than pathogenic behaviour.
A national one-day prevalence survey of nosocomial infections was carried out in March 1984 in 106 Belgian acute-care hospitals involving 8723 patients of whom 6130 had undergone surgery. Three infections were studied: surgical wound infection, bacteraemia and urinary-tract infection. One or more of these three infections was recorded in 9.3% of all patients and in 11.8% of surgical patients. Prevalences increased with increasing duration of hospital stay and with higher ages, but the association of HAI with age was no longer significant after correction for duration of hospital stay. Prevalences varied considerably in different specialties. After adjustment for age and duration of stay, there was no association between perioperative antibiotic prophylaxis and the prevalence of the infections studied, but bias due to selection of higher risk patients in the antibiotic group was probable. Larger hospitals had a higher overall prevalence, but populations differed according to the size of the hospital. Bacteraemia was strongly associated with the presence of an intravenous catheter, and urinary-tract infection with a urinary catheter.
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