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Viral infections are known to modulate the upper respiratory tract microbiome, but few studies have addressed differences in the nasopharyngeal microbiome following SARS-CoV-2 infection. Using nasopharyngeal swab medical waste samples from 79 confirmed SARS-CoV-2 positive and 20 SARS-CoV-2 negative patients, we assessed microbiome composition with metagenomic sequencing. COVID-19 status and breathing assistive device use was associated with differences in beta diversity, principal component analyses, community composition and abundance of several species. Serratia more frequently appeared in COVID-19 patient samples compared to negative patient samples, and Serratia, Streptococcus, Enterobacter, Veillonella, Prevotella, and Rothia appeared more frequently in samples of those who used breathing assistive devices. Smoking and age were associated with differences in alpha diversity. Cross-sectional differences in the microbiome were apparent with SARS-CoV-2 infection, but longitudinal studies are needed to understand the dynamics of viral and breathing treatment modulation of microbes.

Fluorescent antibody (FA) reagents for Salmonella produced by Difco, Sylvana, and Clinical Sciences, Inc., were evaluated for physicochemical and performance characteristics. The Difco panvalent (A through 064) and the Difco polyvalent (A through S) were similar in physicochemical characteristics. They had less than 60% gamma globulin with 3% albumin and had fluorescein to protein (F/P) ratios of less than 10. The Sylvana conjugate had 81% gamma globulin with less than 1% albumin. Its F/P was 33.9. The Clinical Sciences reagent contained 75% unlabeled albumin as packaged in the Fluoro-kit. Analysis of the original conjugate showed 86.5% gamma globulin with only 0.5% albumin. The (F/P) was 32.8. The performance characteristics were determined by using a variety of Enterobacteriaceae and food and feed samples. All conjugates stained the homologous Salmonella strains. The majority of cross-reactions were limited primarily to the Arizona, Citrobacter , and Escherichia coli groups. The Difco panvalent was more reactive with heterologous organisms. It stained 89% of the Arizona compared with 42% stained by the Difco polyvalent (A through S) and 39% stained by the Sylvana and Clinical Sciences reagents. We found 90% agreement between FA and culture when the Difco polyvalent was used to examine food and feed samples and 94% agreement when the Clinical Sciences Fluoro-kit was used on another group of samples.

Precoated cellulose thin-layer chromatograms were used to detect the production of guanosine 5′-phosphate from guanosine and p -nitrophenylphosphate by whole-cell preparations. One-hundred per cent of Serratia (163 strains) and 84% of E. liquefaciens (15 of 18 strains) produced the nucleotide. All other Enterobacter (23 strains), Klebsiella (10 strains), and E. coli (10 strains) were negative for the production of this nucleotide. The entire test procedure could be carried out in 4 hr. It is proposed that E. liquefaciens is more closely related to Serratia than Enterobacter and that reclassification of these organisms should be investigated.

Two aerobic, gramnegative, red-pigmented, rod-shaped bacteria were compared morphologically and physiologically with Serratia species, which they resembled superficially. The pigment produced by the marine isolates was shown to be similar to prodigiosin, the red pigment of S. marcescens . The isolates had a single polar flagellum, were oxidative, and did not produce acetoin from glucose or reduce nitrates, which made them distinct from both S. marcescens and S. marinorubra . The latter conformed well to the descriptions of S. marcescens in Bergey's Manual . The marine isolates displayed an absolute growth requirement for sea water or its equivalent. The growth requirement for sea water was replaced by sea-water levels of sodium, potassium, and magnesium chloride. Pigment was produced only when this salt mixture was further supplemented with calcium chloride. Neither sea water nor a high salt level was required for growth or prodigiosin synthesis by the Serratia species examined.

Inasmuch as all living things usually require a high content of water either internally or externally, or both, it is remarkable that microorganisms, especially spore forms, can sometimes withstand an extreme desiccating environment. Any success achieved by chemical or physical means in modifying viability, that is in hastening or preventing death of the desiccated cell, has implications in many different fields. The various techniques exploited during the last 45 years in the preservation of bacteria by drying have been reviewed in an interesting and very useful manner by Fry (1954). Although he commends Naylor and Smith (1946) on the logical development of their stabilizing medium for the freezedrying of Serratia marcescens, he points out that its general applicability would have to be tested with more sensitive organisms. The present study of preservation by drying is also limited to S. marcescens but a considerable variety of new substances has been tried besides the Naylor-Smith components. Some of our results should find application in the preservation of other organisms freeze-dried under similar conditions. Experiments with sensitive strains of yeast and bacteria will be reported in a later paper.

Irradiation of aerosols of either Escherichia coli or Serratia marcescens with simulated solar (xenon) radiation caused a significant decrease in viability. When sodium fluorescein was employed to determine the physical loss of organisms from the aerosol, an additional adverse effect upon survival was noted. The decay curves indicated that at least two mechanisms of inactivation were operative, one due to aerosolization, the other to irradiation. After collection from aerosols, both species of microorganisms grew better on blood agar base than on Casitone agar, but this finding did not appear to be related to the effect of irradiation.

Dilution cultures of 30 samples of ground black pepper yielded an average of 39,000 colonies of fungi per g, with a range of 1,700 to 310,000 per g. Total numbers of colonies of bacteria from 11 samples averaged 194,000,000 per g, with a range from 8,300,000 to 704,000,000 per g. A variety of fungi grew from nearly all surface-disinfected whole peppercorns that were cultured. Thirteen samples of ground red pepper from the United States yielded an average of 1,600 colonies of storage fungi per g and an equal number of other fungi; five samples from India yielded an average of 78,900 colonies of storage fungi per g and 169,400 colonies of other fungi per g. Among the fungi from both black and red pepper were Aspergillus flavus and A. ochraceus , some isolates of which, when grown for 8 to 10 days on moist autoclaved corn and fed to white rats or to 2-day-old Pekin ducklings, were rapidly lethal to them. Aflatoxin B 1 was isolated from one of the samples of corn on which A. flavus from black pepper was grown. Among the bacteria isolated from ground black pepper were Escherichia coli, E. freudii, Serratia sp., Klebsiella sp., Bacillus sp., Staphylococcus sp., and Streptococcus sp. No cultures of Shigella or Salmonella were found.

The effect of different seawaters on survival and growth of biotin-, isoleucine-, and uracil-requiring mutants of the marine bacterium, Serratia marinorubra , has been investigated. Samples of seawater were collected from coastal waters, the California Current, and central North Pacific waters at depths of 1, 25, 50, 100, 250, and 500 m. The growth or survival of the test bacterium in basal medium prepared in these seawater samples was determined. The control water was synthetic or charcoal-treated natural seawater. In several experiments, the metabolite required by the bacterium was added to the basal medium 24 hr after inoculation, and the growth response was determined. Depending on the source, the seawater samples were both stimulating and inhibitory. Surface waters were more inhibitory than those taken at depth, where, in some cases, bacterial growth occurred. Seawater inhibition was related more to station depth than to the location of the station. The most toxic effects were found against the uracil-requiring mutant; the least, against the isoleucine-requiring mutant. The results of these studies and some laboratory experiments indicate that seawater toxicity is not primarily associated with the physical and biological properties of a particular water mass and that the same factor(s) may be responsible for the rapid death of bacteria in all waters.

The activity of a new semisynthetic penicillin, α-carboxyl-3-thienylmethyl penicillin (BRL-2288) was determined against 535 clinical isolates of gram-negative bacilli, by using the tube dilution technique. Nearly 80% of isolates of Proteus spp. were inhibited by 3.12 μg or less of this antibiotic per ml. BRL-2288 was as active as ampicillin against Escherichia coli. It was slightly more active than carbenicillin or 6-( d -α-sulfoaminophenylacetamido)-penicillanic acid against Pseudomonas sp., with over half of the isolates being inhibited by 50 μg or less of BRL-2288 per ml. Isolates of Klebsiella sp. were routinely resistant to this antibiotic. The drug was bactericidal against most sensitive organisms. BRL-2288 was less active against large inocula. A strain of Pseudomonas sp. which developed resistance to carbenicillin also developed resistance to BRL-2288 simultaneously.

Bacteria have been shown to be present in fresh normal tomatoes. The frequency of their presence differed widely between different fields. Bacterial populations within the tomatoes showed a distinct gradient, being largest in the connective tissue at the stem end and decreasing through the central core towards the peripheral and distal tissue. Application of Serratia to the sepals of young tomato fruits often resulted in their recovery from within tissue of the mature fruit. These findings lend support to the theory that the bacteria enter the fruit through the connective tissue at the stem end.

Studies were undertaken for the differentiation of members of the Klebsiella-Enterobacter ( Aerobacter )- Serratia division by biochemical tests and antibiotic susceptibility. A total of 67 cultures were tested. Strain identification was readily accomplished with the use of motility tests and arabinose fermentation. In addition, a practical schema, based on sensitivity pattern, proved valuable in the classification of the different strains. Most (if not all) Klebsiella strains were susceptible to cephalothin, and all were sensitive to colistin. Enterobacter strains were resistant to cephalothin but susceptible to colistin. In contrast to those other members of the group, all Serratia strains were resistant to both cephalothin and colistin. The combination of a limited number of biochemical reactions and single-disc sensitivity tests appears to be a logical approach for the tentative identification of Klebsiella-Enterobacter ( Aerobacter )- Serratia strains.

Mycobacterium tuberculosis strain Erdman, M. bovis (BCG), and M. phlei showed a 1- to 2-log drop in viability after exposure to ultraviolet light compared to a 5-log drop over the same period for Staphylococcus albus, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis , and Serratia marcescens. L. monocytogenes showed an initial resistance to ultraviolet inactivation, but later the inactivation rate increased sharply. The significance of these findings with regard to the use of S. marcescens as a test organism for determining the bactericidal efficiency of ultraviolet lamps used to sterilize equipment contaminated with tubercle bacilli is discussed.

The activity of three α-(substituted-ureido) penicillins was evaluated in vitro against 599 clinical isolates of gram-negative bacilli, by use of the broth-dilution technique. At a concentration of 12.5 μg or less/ml, BL-P1597 inhibited 90% of isolates of Pseudomonas sp., 56% of Enterobacter sp., 67% of indole-positive Proteus spp., 72% of Escherichia coli , and 85% of Proteus mirabilis. BL-P1654 had similar activity, whereas BL-P1532 was much less active. At a concentration of 25 μg or less/ml, BL-P1597 also inhibited nearly 60% of isolates of Klebsiella sp. and nearly 40% of Serratia sp. BL-P1597 and BL-P1654 were as active as ampicillin and carbenicillin against E. coli and P. mirabilis. They were less active than carbenicillin against indole-positive Proteus spp. Both drugs were substantially more active than carbenicillin against Pseudomonas sp. A strain of Pseudomonas sp. which developed resistance to carbenicillin also developed resistance to the α-(substituted-ureido) penicillins simultaneously.

A polyvalent OH conjugate for Salmonella O groups A through I, K, L, and O was prepared and tested against pure cultures of salmonellae, nonsalmonellae, and a variety of food, fecal, and environmental specimens. Examination of pure cultures revealed that the conjugate gave negligible staining with representative strains of Shigella, Proteus, Providence, Serratia , and Pseudomonas . However, it stained 12% of the Escherichia coli and Citrobacter freundii strains and 36% of the Arizona strains. Over 1,200 specimens of various types were examined by both fluorescent-antibody (FA) and cultural procedures. Results indicate that, when used with discretion, FA screening can be a useful tool for rapid presumptive indication of the presence of salmonellae. The need for careful selection of strains used for preparing antisera and the importance of adequate evaluation of Salmonella FA reagents are discussed.

Three hundred twenty-nine strains of the tribe Klebsielleae were compared by several biochemical tests and by susceptibility to selected antibiotics. Biochemical tests included urease, amino acid decarboxylase, and hydrogen sulfide production; fermentation of lactose and dextrose; motility; and tests in the IMViC (indole, methyl red, Voges-Proskauer, citrate) series. The isolates were: Klebsiella species, 67.5%; Enterobacter species, 28%, and Serratia species, 4.5%. Minimal inhibitory concentrations of cephaloridine, cephalothin, and a new cephalosporin, cephalexin, and of ampicillin were determined by the agar dilution procedure. Cephalosporins at 20 μg/ml or less inhibited 90% of the Klebsiella strains but only 15% of the Enterobacter strains. Ampicillin inhibited 27% of Enterobacter strains and 17% of Klebsiella strains. Serratia isolates were insensitive to the cephalosporins and ampicillin. The results suggest that precise identification of this group to the generic level can be accomplished readily in the clinical laboratory and that such information is helpful in the preliminary selection of an antibiotic for treatment of clinical infections.

Serratia marcescens strains from three hospitals in the city of New York were tested for antibiotic susceptibility patterns and the presence of transmissible antibiotic resistance factors. There appears to be a pattern characteristic for each hospital with regard to the sensitivity to nalidixic acid, tetracycline, chloramphenicol, and sulfonamides, whereas the resistance to ampicillin, cephalothin, and streptomycin is similar in the strains isolated from all three hospitals. In one hospital, a single type of R factor was found which transfers resistance to streptomycin, kanamycin, ampicillin, and sulfonamides, whereas strains isolated from a second hospital transfer only ampicillin resistance. No R factors could be detected in multiply resistant Serratia strains isolated in a third hospital. The presence of a single type of R factor probably reflects the relative ecological isolation of S. marcescens and could be useful for epidemiological studies of hospital infections with Serratia.

A procedure is described for identifying members of the family Enterobacteriaceae isolated from clinical specimens. The methods are based on primary differentiation of the various groups of bacteria by the use of Kligler Iron Agar and lysine-iron-agar. For identification of Salmonella, Shigella , and Arizona group organisms from stools, Triple Sugar Iron Agar and lysine-iron-agar are employed. The usefulness of this schema for diagnostic bacteriology laboratories is discussed. It is not intended to replace methods used in reference or research laboratories.

Bacteriological analyses were performed on fecal swabs and the aquarium water of 27 individually purchased specimens of the small green pet turtle, Pseudemys scripta elegans . Representatives of Aeromonas, Citrobacter, Enterobacter, Klebsiella, Proteus, Salmonella , and Serratia were isolated. Enterobacter, Klebsiella , and Salmonella were encountered in 20% or more of the specimens, whereas Aeromonas was isolated from 63%. Klebsiella pneumoniae counts ranged from 10 3 to 10 4 per milliliter of aquarium water, whereas Aeromonas routinely exceeded 10 4 per milliliter. Aeromonas cultures from turtles were identical to 7 human isolates in some 29 biochemical tests. On the basis of our findings, we question whether the Salmonella -free certification program alone is sufficient to render these reptiles as safe pets.

Two enrichment broths and four plating media were compared for efficiency of detection of enteric pathogens from 1,597 stool specimens. Of 170 salmonellae isolated from the composite of all methods, direct streaking yielded but 54%, whereas enrichment in gram-negative broth found 87% and Selenite-F broth 97%. By contrast, gram-negative broth produced 100% of the 17 shigellae, Selenite-F broth but 77%, and direct streaking only 59%. Thus, enrichment methods produced almost twice the number of both pathogens as direct streaking. Comparison of the plating media revealed xylose lysine deoxycholate agar (XLD) and Hektoen enteric agar to be equal in their abilities to find both pathogens. Both were moderately better than Salmonella-Shigella agar and markedly superior to eosin methylene blue agar. XLD fround 83% of salmonellae produced by the composite of four media and 90% of the shigellae. Hektoen enteric agar found 80% of both. Salmonella-Shigella agar detected 74 and 68%, respectively, and eosin methylene blue agar only 42 and 63%. The numbers of false positives accruing to each medium, however, showed Hektoen enteric and Salmonella-Shigella agars to produce more than twice as many false-positive plates as XLD. Similarly, Selenite-F broth resulted in many more false-positives for all plating media than did gram-negative broth. Consequently, the index of validity, which equates successful isolation of pathogens with total pickings, favored XLD and gram-negative broth as the media of choice, with direct streaking the poorest method by all counts.

Numerous selective media, available commercially, act by suppressing “normal” bacterial inhabitants of the intestine while permitting the growth of so-called pathogenic representatives of the family Enterobacteriaceae . This investigation attempts to evaluate the action of Salmonella-Shigella (SS) agar, xylose lysine desoxycholate (XLD) agar, and hektoen enteric (HE) agar. Salmonellae and shigellae, isolated from clinical material, were mixed in various ratios with escherichiae, Klebsiella-Enterobacter-Serratia group bacteria, and members of the tribe Proteeae , also of clinical origin. Several of the mixtures were plated in multiple dilutions on the three media. Stools in preservative were also used for evaluation of the media after the addition of definite numbers of the pathogenic bacteria. Results indicate that SS agar suppresses the shigellae along with the autochthonous members of Enterobacteriaceae . XLD and HE agars readily permit the recovery of shigellae as well as salmonellae. This recovery is not obscured by the higher yield of other species obtained with these media.

Gram-nagative organisms were tested with commercially available reagentimpregnated strips (PATHO-TEC). Of the 291 strains, all were tested by using seven paper tests and their conventional counterparts. Excellent correlation was obtained with the oxidase, phenylalanine-deaminase, and Voges-Proskauer tests. Indole tests made on liquid medium cultures also gave complete correlation, but some false-negative results with indole-positive Proteus strains were obtained when growth from solid medium was tested by the strip method. Paper strip urease tests were positive within 2 hr with all Klebsiella and some Serratia, Herellea , and Citrobacter strains as well as with Proteus strains. Approximately 15% of citrate strip test results differed from those of the conventional tests, and reproducibility was poor on retest. The lysine decarboxylase strip test showed a number of discrepancies and posed problems of interpretation and readability. Paper reagent strip methods are simple and convenient and merit further development to increase the specificity of those which depend on p H change up to that achieved with the Voges-Proskauer, oxidase, phenylalanine, and indole methods.

The R/B Enteric Differential System for identifying enteric bacteria has been evaluated with 451 “unknown” cultures from the stock culture collection of the Center for Disease Control. An average of 89.6% of these cultures were correctly identified by the R/B system, when used as recommended by the manufacturer but without the assistance of serology. This percentage ranged, however, from 47% for Klebsiella to 100% for Serratia and Providencia. Of 11 groups or genera of Enterobacteriaceae tested, only three ( Enterobacter, Serratia , and Providencia ) were identified with 95% or better accuracy. Four groups ( Arizona, Citrobacter, Escherichia , and Salmonella ) attained 90 to 95% accuracy of identification, and three groups ( Edwardsiella, Proteus , and Shigella ) scored between 85 and 90% accuracy. We recommend the R/B system as a screening device which is reasonably successful in grouping bacteria but not as a substitute for more exacting conventional procedures.

Eighty-five strains of Serratia were speciated. The majority were Serratia marcescens and were recovered from a variety of clinical specimens. S. liquefaciens and S. rubidaea were recovered only from sputum.