Acta pathologica, microbiologica, et immunologica Scandinavica. Section B, Microbiology最新文献

The diagnostic performance of six methods for bacteriuria testing has been studied in 781 urine specimens obtained in primary health care, using conventional culture as reference method. The cut-off limits for classification of test results into positive and negative have been optimized with respect to diagnostic performance in primary health care. With optimized tests the following diagnostic efficiencies were obtained: Bacterial ATP, 0.94; Bacterial count in sediment, 0.93; Nitrite test, 0.92; Dipslide test, 0.92; White cell count in sediment; 0.87; Goffulocyte esterase test; 0.83. The diagnostic performance was also studied for all combinations of two tests. The highest diagnostic efficiency (0.96) was obtained by combining the ATP and dipslide tests. High diagnostic efficiencies can be obtained by a rapid primary test, using other tests for follow-up testing of specimens with intermediate or uninterpretable primary results. The most promising results were obtained by using ATP as the primary test, with follow-up testing of specimens with 3-25 nmol/l of ATP (12 per cent of the specimens). Follow-up testing by conventional culture resulted in overall diagnostic efficiency of 0.98. By performing the nitrite test on specimens with intermediary ATP-results, 81 per cent of the patients with UTI can be classified without culture. Only patients with intermediary ATP and negative nitrite results (10 per cent of the total number) will have to wait for final diagnosis based on conventional culture. Some alternative strategies to combine available methods are discussed in detail. Major advantages of the ATP test are that the test can be performed while the patients are waiting; it provides a numerical and objective result, and, in contrast to culture, it is not influenced by adhesion of bacteria to somatic cells.

Streptococcus sanguis (serogroups H and W) strains are frequently competent in genetic transformation. In a collection of 18 strains of S. sanguis isolated from blood cultures, 12 strains were spontaneously competent in transformation by streptomycin-resistant DNA, and three strains were induced to competence by the use of culture filtrates containing competence factor (CF). Culture filtrates from spontaneously competent S. sanguis strains only induced competence in transformation of strains of the same species. In addition to the three "constitutional" types of S. sanguis with regard to specificity of transformation previously reported (originally represented by the strain Challis, 13b and NCTC 7863), a possible fourth type, (represented by strain 21452) was found. Further studies are required to ascertain the role of these types. The "constitutional" types are characterized by the range of activity of their CF's. These specificities seem useful in identification of S. sanguis and its separation from S. mitis (mitior). Tests of spontaneously competent strains with culture filtrates from other competent strains showed variable effects on the transformation frequencies in different strains.

Of 46 viridans streptococci isolated from cases of probably true bacteremia, 26 strains or 56% could be grouped serologically in the Lancefield system. Eight strains (17%) were identified as serogroup H (characteristic of Streptococcus sanguis), ten strains (22%) as serogroup W (a new group antigen found in S. sanguis) and eight strains (17%) as serogroup K (related to S. mitis (mitior)). The high number of serogroupable viridans streptococci was specially due to the introduction of serogroup W and indicates the importance of this serogroup in cases of bacteremia. A set of six diagnostic tests (production of hydrogen peroxide, arginine and esculin hydrolysis, polysaccharide production, Voges-Proskauer reaction, mannitol fermentation) was used for speciation of the viridans streptococci; in addition, search for spreading zones around the colonies was included in the diagnostic procedure. Spreading zones were only present in S. sanguis and occurred more frequently in group H strains than group W strains. The 46 viridans streptococci were tested in genetic transformation. The prevalence of spontaneous competence in strains isolated from the blood was high, particularly in S. sanguis serogroup H (88%) and W (50%). For serogroup H, spontaneous competence was found as frequently among invasive strains as among carrier isolates previously studied.

Enterotoxigenic Escherichia coli of human and procine origin were characterized with respect to their O and H antigens, fimbrial antigens, and type of enterotoxin produced. Enterotoxin production was determined by bioassay (infant mice) and enzyme-linked immunoassay (ELISA). The presence of genes coding for the enterotoxins was determined by DNA-DNA hybridization. The number and molecular size of plasmids in the enterotoxigenic strains were determined by gel electrophoresis. Strains with the same serological pattern showed different plasmid profiles and could thereby easily be separated. One strain of porcine origin possessed only one plasmid, but produced both heat-labile enterotoxin and the F4 antigen (formerly K88), which is an unusual combination.

Campylobacter is one of the most common causes of diarrhoea in humans. Different typing systems have been put forward as aids to improved understanding of the epidemiology and clinical signs of the disease. In the present investigation we have adopted indirect haemagglutination for serotyping of heatstable (Penner) antigens and direct slideagglutination for heatlabile (Lior) antigens. All the strains from the patients (n = 277) seeking medical care for diarrhoea at the East Hospital, Göteborg, Sweden over 21 months were studied. With 19 antisera against heatstable antigens, 79.8% of the domestic strains were typable and 73.8% of the foreign strains. For the heatlabile antigens corresponding figures were 94.2% and 87.2%. There was a great variety of combinations of heatstable and heatlabile antigens on the strains. No marked relation between one antigen or antigen combination and clinical sign of disease was found. We conclude that serotyping is mainly useful for epidemiological studies. A limited number of antisera can be used for typing the majority of strains. If a choice is to be made, typing for heatlabile antigen seems simple and gives somewhat higher typability.

Recently, we reported that conjugal transfer of plasmid pERL1, determining i.a. erythromycin resistance (Emr), into group A streptococci could trigger the expression of anti-phagocytic activity, adhesiveness, opacity factor and capacity to bind immunoglobulin Fc-parts and beta 2-microglobulin. In the present study, ethidium bromide treatment of Emr transconjugants allowed the selection of "cured", erythromycin sensitive (Ems) mutants. This procedure did not affect the expression of the abovementioned characteristics. However, when plasmid pERL1 was again transferred to two such mutants, the "secondary", Emr transconjugants obtained showed lack of each of these properties. Our experiments thus demonstrated a "switch-on" as well as a "switch-off" effect, exerted by the same plasmid, pERL1, on some major pathogenic properties of group A streptococci.

Ninety-seven strains of clinically isolated Corynebacterium strains, probably identical with Corynebacterium JK, are described especially in regard to growth in relation to different lipid substances. The corynebacteria formed a homogeneous group of strict aerobic slow-growing, catalase-positive, urease-and-nitrate-negative typical coryneform rods. Acid was produced from glucose and maltose. Growth was stimulated in the presence of different lipid substances and lipodependence was suggested by satellite growth only around oleic acid drops on otherwise lipid-depleted agar plates. Generally the isolated corynebacteria were resistant to clinically achievable concentrations of penicillins, cephalosporines and aminoglucosides but uniformly sensitive to vancomycin and rifamycin.

A total of 849 gonococcal strains from 659 patients in Copenhagen (Denmark), Helsinki (Finland), Oslo and Trondheim (Norway) and Stockholm (Sweden) were included in the study. Using coagglutination reagents with polyclonal and monoclonal antibodies the strains were serogrouped into the previously described gonococcal serogroups W I, W II and W III. W II strains were dominating in all five towns (60.0%-70.9% of the strains), but W III strains were rarely isolated. W I strains were more frequent among women than among men. With the monoclonal reagents, W I, W II and W III strains could be further subdivided into 12, 29 and two different serovariants (serovars), respectively. One of the W I serovars was dominating (76%-94% of W I strains) in all five towns, and apart from this serovar, only three to five other W I serovars were seen in each town. Of W II strains, on the other hand, a greater variety of serovars were seen: between six in Trondheim and 17 in Oslo, and no one was dominating as among W I strains. Different W II serovar patterns were found in the different towns. Even between the two participating laboratories in each of the towns, Oslo and Helsinki, differences were noted. The epidemiological value of this is discussed. Ten of the 11 beta-lactamase-producing gonococcal strains isolated belonged to unusual serovars. None of the monoclonal coagglutination patterns corresponded to a single polyclonal pattern. There were, however, some relations between the two systems. In earlier studies it was shown that in smaller Swedish towns W I strains dominated. A hyphothesis about protective anti-Protein I antibodies is discussed to explain the differences in distribution of W I and W II strains between smaller and larger towns and between women and men.

A total of 965 strains of Micrococcaceae isolated from 200 patients, personnel, and air in a department of cardiac surgery were classified by means of Baird-Parker's scheme. The majority of strains were identified as Staphylococcus epidermidis (S. epidermidis) biotype 1, but S. epidermidis biotype 4 accounted for c. 25% of isolates from patients post-operatively. Pre-operative isolates were generally sensitive to most antibiotics tested while post-operative strains of coagulase-negative Micrococcaceae from patients and isolates from personnel and air were frequently multiply-resistant. Strains of Staphylococcus aureus (S. aureus) were sensitive or resistant only to penicillin. More patients were colonized with coagulase-negative Micrococcaceae after operation than at admission to the hospital (p less than 0.001), while the frequency of S. aureus carriers was the same before and after operation and equal to the frequency found earlier. The frequency of S. aureus carriers among the personnel, however, was lower than reported earlier (10%). Multiply-resistant strains of S. epidermidis seem to have replaced resistant strains of S. aureus as the predominant hospital saprophyte among Micrococcaceae.