Serratia marcescens meningitis.

A case of Serratia marcescens meningitis in a 66-year-old man is reported. The infection occurred 4 weeks after apparently successful otic surgery, and a nidus of infection in the middle ear was established at autopsy. This is the second case of S. marcescens meningitis following ear surgery reported in the English-language literature.     

A generalized transducing bacteriophage for Serratia marcescens.

Using Serratia marcescens 2170 harbouring plasmid pTroy11 (encoding for LamB), and lambda (lambda:: Tn5) we constructed a collection of 25 auxotrophic mutations induced by Tn5 insertions. These mutants permitted the use an easy screening method for generalized transducing bacteriophages. Out of twelve bacteriophages isolated from natural sources only one (phage 3M) was able to transduce all Tn5 insertions tested. The preliminary characterization of bacteriophage 3M indicates that it belongs to the Myoviridae family.     

Cross-infection with Serratia marcescens

Cross-infection in a urological unit due to Serratia marcescens is reported. The bacteriology of the organism and its mode of spread are described. It is suggested that Serratia marcescens may be a more virulent organism than is generally believed, especially in situations in which there is an excess of mucus.     

Identification of capsular antigens in Serratia marcescens.

Previous studies with 31 strains of Serratia marcescens, including 28 reference O-serotype strains, have indicated that 19 of them have an acidic polysaccharide which copurifies with lipopolysaccharide during phenol-water extraction. Polysaccharide in crude extracts from 18 of the 19 strains was precipitated with Cetavlon (hexadecyltrimethyl ammonium bromide), and capsules were demonstrated around these 18 strains by Indian ink exclusion zones. Capsule-antibody binding by the Quellung reaction suggested that the acidic polysaccharide formed the capsule around the bacterial cells. Anticapsular (anti-K) antibody was detected in reference O antisera which had been prepared against boiled whole cells. Cross-titration and absorption studies revealed 14 different K antigens among these strains.     

Nosocomial outbreak of nitrate-negative Serratia marcescens infections.

Bacteremia due to multiply-antibiotic-resistant Serratia marcescens occurred within 1 week in four patients who were in adjacent beds in an intensive care unit. The strains were serotyped as O14:H12 and were nitrate negative. This unusual biochemical marker was useful in the investigation of the outbreak.     

Pulmonary infection with Serratia marcescens

A case of pulmonary infection, presenting with fever and productive cough (pseudohaemoptysis) was diagnosed as having infection with Serratia marcescens on performing culture and sensitivity tests. The organism was confirmed upto species level using the standard biochemical tests.     

Combined serotyping and biotyping of Serratia marcescens.

The API (Analytab Products, Inc., New York, N.Y.) biotypes of 117 clinical isolates of Serratia marcescens were determined and fell into 13 different patterns. The O and H antigens were determined by tube agglutination, and 27 serotypes were identified. The biotype and serotype appeared to vary indepently. Serotyping and biotyping combined divided these isolates into 56 different types. There was a problem interpreting the end points for inositol fermentation and urease production, which could affect reproducibility of API biotypes. Biotyping is a simple way of screening for possible nosocomial outbreaks of S. marcescens.     

Rapid identification of Serratia marcescens by coagglutination.

All 20 O serotypes of Serratia marcescens produce a common, soluble antigen. Crude antigen was obtained by ammonium sulfate precipitation of spent growth medium, antiserum was produced in rabbits, and a coagglutination test for rapid identification of S. marcescens was developed. A total of 701 clinical isolates of gram-negative bacilli were examined, and a 100% correlation between biochemical identification of S. marcescens and identification by coagglutination was found.     

Co-transduction mapping in Serratia marcescens

The linkage of 34 auxotrophic markers in strain HY of Serratia marcescens was studied by means of transductions with phages x and y. The markers could be ordered into 18 loci of different auxotrophies by transduction crosses with phage x (markers in trans-position) 17 of which showed to be linked to at least one of the other loci. A linear map of this section of the genome was constructed. It corresponds well to the map of 8 loci derived from transductive crosses (markers in cis-position) with phage y. Since a virion can transduce about 5 loci at the same time the map represents only a small section of the Serratia genome. No similarity to any part of the maps of Escherichia or Salmonella can be detected. It is discussed why most auxotrophic mutations which were induced by nitrosoguanidine map in this small genomic region.     

Differentiation of Serratia marcescens and Serratia liquefaciens by tests for lipase and phospholipase production.

The production of lipase and phospolipase by certain members of the Enterobacteriaceae was examined by thin-layer chromatography of resting-cell suspensions incubated with triolein or lecithin. Most strains of Serratia marcescens produced both enzymes while most strains of Serratia liquefaciens exhibited strong lipase but only a minor phospholipase activity. Enterobacter spp. (25 strains), Klebsiella pneumoniae (20 strains), Escherichia coli (15 strains), Citrobacter freundii (7 strains) and Proteus spp. (20 strains) lacked both types of enzymic activity except for the following: three strains of Enterobacter cloacae, two of Proteus mirabilis and three of Proteus vulgaris possessed slight lipase activity; about one-half of the Enterobacter aerogenes and Enterobacter hafniae strains examined produced slight phospholipase activity. It is suggested that tests for lipase and phospholipase should be used in conjunction with those for DNAase production and sugar fermentation for the differentiation of S. marcescens and S. liquefaciens.     

Oxygen uptake by Serratia marcescens

Oxygen uptake was studied in cell suspensions of Serratia marcescens BIZIO supplied with various types of substrates. Of the polyols provided as substrates glycerol was the best stimulant of oxygen uptake followed by D-mannitol and sorbitol. D-xylitol and meso-inositol stimulated oxygen uptake only after a long lag. The hexose sugars as well as their phosphorylated derivatives were better than the pentoses as stimulants of oxygen uptake. Ammonium accelerated oxygen uptake in the presence of fructose, glucose or mannitol. Oxygen uptake in the presence of either glucose-l-phosphate or glucose-6-phosphate was independent of NADP⁺, indicating a non-enzymic system.     

Comparison of two methods for bacteriocin typing of Serratia marcescens.

Two methods of bacteriocin susceptibility typing for Serratia marcescens were compared. A total of 80 epidemiologically unrelated isolates from patients in a single hospital were typed by the cross-streaking method and the mitomycin C-induced (spotting) method. The cross-streaking method was found to be more discriminatory than the spotting method. Using the cross-streaking method, it was possible to differentiate 50 bacteriocin groups out of the 80 isolates, whereas only 31 groups could be obtained with the spotting method. The reproducibility and percentage typability of the cross-streaking method (82.5 and 93.75%, respectively) were found to be as good as, if not better than, those of the spotting method (78.75 and 90.0%, respectively). Other factors, such as lower economic cost, technical simplicity, and the relative ease in the scoring of results, indicate a preference for the cross-streaking method. The findings of this study support the choice of the cross-streaking method for the bacteriocin typing of S. marcescens in epidemiological studies.     

O-serotyping Providencia alcalifaciens.

The O-serotyping scheme for Providencia was tested on Providencia alcalifaciens isolates collected mostly from two hospitals. The specificites of the somatic (O) antigens of P. alcalifaciens were found to be different from those of Providencia stuartii, and separation of the Providencia typing scheme to allow separate typing of each species led to more efficient typing. All but 4 of 86 isolates were typable. Eighteen serotypes occurred among 53 typable isolates obtained from a pediatric hospital, and 11 occurred among 19 isolates from a general hospital. Thirty-two percent of the isolates from the pediatric hospital belonged to serotype O3, the most frequently isolated and most widely distributed type. The use of the serotyping scheme for P. alcalifaciens is advocated for further studies to examine strains of the species for enteropathogenic types.     

Bacteriocin typing of Serratia marcescens. A simplified system.

The authors describe a simplified system for the detection of bacteriocin production by Serratia marcescens with the use of six indicator strains, which include Escherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Enterobacter aerogenes (two strains), and Serratia rubidaea grown on arabinose minimal medium plates. Of the 64 possible bacteriocin types, 11 were observed; 66% of the isolates tested were found to be one of three types. Occasionally more than one bacteriocin type was observed in an individual specimen; however, serotyping or antibiograms, or both, also indicated this was a different strain. The marcescin types were stable markers. With the use of this technic, different endemic strains of Serratia were shown to predominate in various areas of the hospital. In addition, when urinary tract isolates were compared with respiratory tract isolates, significant differences were found in the predominate types. The typing of these isolates by bacteriocin production was supported by serotype and antibiotype findings. The results suggest that this simple system may be a useful tool in a general hospital.     

Immunophysical characterization of human isolates of Serratia marcescens.

The immunophysical characteristics of 29 Serratia marcescens strains isolated from hospitalized patients in three different cities were studied. Their outer membrane antigens were compared by solid-phase radioimmunoassay inhibition, and their proteinase K-treated, whole-cell lysates were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis. The strains had a limited number of unique outer membrane lipopolysaccharide (LPS) and capsular polysaccharide (K) antigens. By solid-phase radioimmunoassay inhibition, these strains could be divided into four distinct LPS and five K antigenic groups. By SDS-PAGE, the LPS groups could be further divided into three distinct SDS-PAGE core polysaccharide profiles and five distinct O-side-chain polysaccharide profiles. Immunoblot analysis with rabbit antiserum confirmed the limited heterogeneity of these isolates. Of the strains tested, no PAGE profile was unique to blood or nonblood isolates or to organisms collected from a given hospital. Variability of O and core PAGE profiles was not a function of organism growth cycle. Five representative Serratia strains were tested by SDS-PAGE and immunoblot analysis and in a bactericidal assay with normal human serum. We found that (i) the normal human serum had antibodies to the LPS of each of the strains, (ii) the anti-LPS antibody measured by immunoblot did not correlate with the level of bactericidal activity in the normal human serum, (iii) three of four sepsis isolates were serum sensitive, (iv) two Serratia strains serum sensitive in log-phase growth became serum resistant in late stationary-phase growth and under limiting nutrient conditions, and (v) no LPS PAGE profile distinguished serum-sensitive from serum-resistant strains.