Impact of climate change on foodborne infections and intoxications

Background

Temperature, precipitation, and humidity are important factors that can influence the spread, reproduction, and survival of pathogens. Climate change affects these factors, resulting in higher air and water temperatures, increased precipitation, or water scarcity. Climate change may thus have an increasing impact on many infectious diseases.

Methods

The present review considers those foodborne pathogens and toxins in animal and plant foods that are most relevant in Germany, on the basis of a selective literature review: the bacterial pathogens of the genera Salmonella, Campylobacter and Vibrio, parasites of the genera Cryptosporidium and Giardia, and marine biotoxins.

Results

As climate change continues to progress, all infections and intoxications discussed here can be expected to increase in Germany.

Conclusions

The expected increase in foodborne infections and intoxications presents a growing public health risk in Germany.

Choline fermentation by Desulfovibrio desulfuricans

Baker, F. D. (Western Reserve University, Cleveland, Ohio), H. R. Papiska, and L. Leon Campbell. Choline fermentation by Desulfovibrio desulfuricans. J. Bacteriol. 84:973-978. 1962-Hayward and Stadtman pointed out that the organism they described as Vibrio cholinicus is closely related to Desulfovibrio desulfuricans. We have established that some strains of D. desulfuricans carry out the same fermentation of choline as does V. cholinicus. We have also shown that V. cholinicus carries out the sulfate-linked fermentation of lactate identical with that of D. desulfuricans. Both organisms have identical reduced cytochrome spectra, with peaks at 417 to 420, 525, and 553 mmu. V. cholinicus also contains the green pigment desulfoviridin, characteristic of D. desulfuricans, which in alkaline solution gives a red fluorescence at 365 mmu. Immunological data from cross-agglutination and absorption tests show that the two organisms have similar antigenic properties. Morphological, cultural, and biochemical studies have also demonstrated that V. cholinicus is indistinguishable from D. desulfuricans. Therefore, V. cholinicus should be regarded taxonomically as a strain of D. desulfuricans.

Nutrition of Vibrio fetus

Smibert, Robert M. (Virginia Polytechnic Institute, Blacksburg, Va.). Nutrition of Vibrio fetus. J. Bacteriol. 85:394-398. 1963.-A chemically defined medium has been developed for the cultivation of both catalase-positive H(2)S-negative and catalase-positive H(2)S-positive strains of Vibrio fetus. A total of 87 strains of V. fetus, representing bovine, ovine, porcine, human, and chicken isolates, were grown in both semisolid and liquid defined media. The medium was also used to isolate V. fetus from the stomach contents of aborted bovine fetuses. The strains investigated did not require purines or pyrimidines. They required nicotinic acid, and were stimulated by other B vitamins. There was considerable variation in the amino acid requirements of V. fetus. Some strains required only one amino acid, and others required many more. The final complete medium contained 18 amino acids and supported growth of all 87 strains. There was no significant correlation between amino acid requirements and source of isolation or biochemical characteristics of V. fetus.

The detection of cholera vibrios in Calcutta waters: the River Hooghly and canals

1. Before undertaking a bacteriological survey of the waters of the Hooghly River and the associated canals a detailed epidemiological study over the past 20 years of cholera, as it affected the individual administrative wards of Calcutta, was undertaken. Sampling points were selected in accordance with the results of this study. Samples of water from the various points were collected at intervals extending from December 1958 to August 1959 in 2½–5 l. amounts. The whole sample in each case was filtered through special filter pads. The pads were first cultured in an enrichment medium from which plate cultures were subsequently made for colony isolation, serological and biochemical examination.

2. The sampling points on the canals were all adjacent to areas where the local endemicity was judged to be high; other points were by bathing ghats, etc. A total of eighty-nine samples covering all the sampling points were examined and Vibrio cholerae were isolated from twelve of these samples, eight of which came from twenty-six samples collected from two sampling points on the Chetla and Circular Canals, respectively.

3. The positive isolations were spread fairly evenly over the whole period of the study which covered both epidemic and non-epidemic periods including the monsoon. Although the incidence of cholera in Calcutta may fall to a low level during non-epidemic periods cases continue to occur throughout the year and the relationship of the maintenance of the infection in the city to the continuous potential infectivity of the open natural waters of Calcutta is discussed.

IDENTITY OF THE PINK-PIGMENTED METHANOL-OXIDIZING BACTERIA AS VIBRIO EXTORQUENS

Stocks, Peter K. (Louisiana State University, Baton Rouge), and C. S. McCleskey. Identity of the pink-pigmented methanol-oxidizing bacteria as Vibrio extorquens. J. Bacteriol. 88:1065-1070. 1964.-Pink-pigmented bacteria isolated from enrichment cultures of methane oxidizers were found to possess similar morphological, cultural, and physiological characteristics. All the strains utilized methanol, formate, oxalate, succinate, glycerol, and benzene as sole carbon sources; methanol, formate, and glycerol afforded best growth. Most strains utilized fructose and ribose; other carbohydrates tested were not available as carbon and energy sources. There was strain variation in the use of hexane, heptane, n-propanol, n-butanol, acetate, and propionate. Methane, ethane, n-propane, and n-butane were not utilized. Our isolates, and Pseudomonas methanica of Harrington and Kallio (not the methane-dependent P. methanica of Dworkin and Foster), Pseudomonas AM1 of Peele and Quayle, Pseudomonas PRL-W4 of Kaneda and Roxburgh, and Protaminobacter ruber den Dooren de Jong are nearly identical with Vibrio extorquens (Bassalik) Bhat and Barker, and should be considered the same species.

GASEOUS ENVIRONMENT AND GROWTH OF MICROAEROPHILIC VIBRIOS

Fletcher, R. D. (University of Connecticut, Storrs), and W. N. Plastridge. Gaseous environment and growth of microaerophilic vibrios. J. Bacteriol. 87:352-355. 1964.-Strains of microaerophilic vibrios from cattle, chickens, man, and sheep were placed in four groups on the basis of catalase and H(2)S production and glycine tolerance. By these tests group I was + - -, group II was + - +, group III was + + +, and group IV was - + +. On yeast extract-agar, the optimal oxygen level was 2.5% for group I, and 5.0% for the other three groups; the optimal carbon dioxide level was 10% for all four groups; the group I strains from man and sheep and the group II strains differed from the group I strains from cattle, by tolerating higher levels of both oxygen and carbon dioxide. On a chemically defined medium, the optimal oxygen level was 1.0%, and the optimal carbon dioxide level was 10% for groups I and II; the group II strains were more sensitive to high levels of carbon dioxide than were group I strains from cattle.

CHEMICALLY DEFINED MEDIUM FOR SOME MICROAEROPHILIC VIBRIOS

Fletcher, R. D. (University of Connecticut, Storrs) and W. N. Plastridge. Chemically defined medium for some microaerophilic vibrios. J. Bacteriol. 85:992-995. 1963.-The medium described supported growth of 22 of 26 catalase-positive, H(2)S-negative vibrios (Vibrio fetus). The strains used were isolated from cattle, chickens, man, sheep, and swine; 10 failed to grow in thiol medium plus 1% glycine (group I), and 16 were glycine-tolerant (group II). Growth on the defined medium was compared with growth on yeast extract agar, blood agar, and thiol agar. Four of the group I strains failed to grow on the defined medium, and growth of seven of the group II strains equaled or exceeded growth obtained on the compared media. Use of synthetic media for determining growth requirements and for possible classification of vibrios is discussed.

MORPHOLOGICAL CHANGES IN GRAM-NEGATIVE BACILLI EXPOSED TO CEPHALOTHIN

Chang, Te-Wen (Tufts University School of Medicine, Boston, Mass.), and Louis Weinstein. Morphological changes in gram-negative bacilli exposed to cephalothin. J. Bacteriol. 88:1790-1797. 1964.-Exposure of gram-negative bacteria to cephalothin (7-[thiophene-2-acetamido]-cephalosporanic acid) revealed the formation of long filaments and large bodies, which were capable of reverting to normal cells when removed from contact with the drug. The degree of morphological change was found to be related to the concentration of antibiotic in which the organisms were suspended. The large bodies were altered by contact with solutions of varying osmolarity. Different species showed variation in the ability to develop large bodies. A relationship between antibiotic sensitivity and the capacity to resist morphological alteration was observed. Though most sensitive gram-negative bacilli were strikingly changed by exposure to cephalothin, naturally resistant ones were unaffected. Organisms made drug-resistant in vitro underwent changes in cellular form which were qualitatively the same but less intense than those which developed in parent strains originally sensitive to cephalothin.

BACTERIOLOGY OF SPOILAGE OF FISH MUSCLE. 3. CHARACTERIZATION OF SPOILERS

A total of 807 bacterial isolates from fresh and spoiling fillets of English sole (Parophrys vetulus) stored at 5 C were classified as to genus and tested for various biochemical activities, including the ability to spoil sterile muscle press juice at 5 C. Production of off-odor, volatile reducing substances, and trimethylamine was used to estimate spoilage. It was found that (i) spoilers could be distinguished from nonspoilers on the basis of the juice spoilage test, (ii) differentiation between spoilers and nonspoilers could not be achieved by means of the usual biochemical tests, (iii) no micrococci, flavobacteria, and "coryneforms" were spoilers, (iv) certain specific subgroups of the genus Pseudomonas consisted exclusively of spoilers whereas others were inactive, (v) the genus Achromobacter likewise consisted of spoilers and nonspoilers, and (vi) "coliforms" could produce spoilage. It was concluded that a method is now available to determine directly and unequivocally the role played in spoilage by various bacterial groups and that it is no longer necessary to rely on indirect evidence.

PREPARATION OF SPHEROPLASTS FROM VIBRIO COMMA

Chatterjee, B. R. (Baylor University College of Medicine, Houston, Texas), and Robert P. Williams. Preparation of spheroplasts from Vibrio comma. J. Bacteriol. 85:838-841. 1963.-Spheroplasts were prepared from several strains of Vibrio comma by lysozyme treatment combined with freezing and thawing of the organisms. The optimal concentration of lysozyme was 50 mug/ml, although some spheroplasts formed at a concentration of 10 mug/ml. Higher concentrations (200 mug/ml) caused lysis of cells along with spheroplast formation. Treatment was carried out in broth cultures containing 15% sucrose, and if the osmotic tension was lowered the spheroplasts lysed. Some motile, spherical cells were present in every preparation. Addition of 3% glycine to broth cultures resulted in rapid transformation of the vibrios into large, spherical bodies. However, these were actively motile, and were not sensitive to a lower osmotic tension. Therefore, they could not be considered as spheroplasts.

REISOLATION AND EMENDATION OF DESCRIPTION OF VIBRIO MARINUS (RUSSELL) FORD

Colwell, Rita R. (Georgetown University, Washington, D.C.), and Richard Y. Morita. Reisolation and emendation of description of Vibrio marinus (Russell) Ford. J. Bacteriol. 88:831-837. 1964.-Sixteen fresh isolates from the marine environment were subjected to taxonomic analysis. From the taxonomic data, both quantitative and qualitative, these strains appear to form a species-group closely related to the Vibrio marinus isolated by Russell from the gulf of Naples in 1891. The V. marinus species description is extended. As a peculiarly marine species, the organisms are distinguished by features of inorganic salt requirement and psychrophilism, as well as by an ability to form acid from glucose anaerobically and a marked curvature of the cells.

THE FINE STRUCTURE AND MODE OF ATTACHMENT OF THE SHEATHED FLAGELLUM OF VIBRIO METCHNIKOVII

The sheathed flagellum of Vibrio metchnikovii was chosen for a study of the attachment of the flagellum to the bacterial cell. Normal and autolysed organisms and isolated flagella were studied by electron microscopy using the techniques of thin sectioning and negative staining. The sheath of the flagellum has the same layered structure as the cell wall of the bacterium, and in favourable thin sections it appears that the sheath is a continuation of the cell wall. After autolysis the sheath is usually absent and the core of the flagellum has a diameter of 120 A. Electron micrographs of autolysed bacteria negatively stained with potassium phosphotungstate show that the core ends in a basal disc just inside the plasma membrane. The basal disc is about 350 A in diameter and is thus considerably smaller than the "basal granules" described previously by other workers.

LYSIS OF BACTERIAL PROTOPLASTS AND SPHEROPLASTS BY STAPHYLOCOCCAL ALPHA-TOXIN AND STREPTOLYSIN S

Bernheimer, Alan W. (New York University School of Medicine, New York, N.Y.), and Lois L. Schwartz. Lysis of bacterial protoplasts and spheroplasts by staphylococcal alpha-toxin and streptolysin S. J. Bacteriol. 89:1387-1392. 1965.-Protoplasts of Bacillus megaterium, Sarcina lutea, and Streptococcus pyogenes, and spheroplasts of Escherichia coli were lysed by staphylococcal alpha-toxin, whereas spheroplasts of Vibrio metschnikovii and V. comma were not. In the spectrum of its lytic action, streptolysin S qualitatively resembled staphylococcal alpha-toxin except for failure to lyse S. pyogenes protoplasts. In contrast to the two foregoing agents, streptolysin O did not lyse protoplasts and spheroplasts. The observations are interpreted in relation to similarities and differences in lipid composition of bacterial and mammalian cell membranes.

BIOCHEMICAL CHARACTERISTICS OF VIBRIO SPUTORUM AND RELATIONSHIP TO VIBRIO BUBULUS AND VIBRIO FETUS

Loesche, Walter J. (Forsyth Dental Center and Harvard School of Dental Medicine, Boston, Mass.), Ronald J. Gibbons, and Sigmund S. Socransky. Biochemical characteristics of Vibrio sputorum and relationship to Vibrio bubulus and Vibrio fetus. J. Bacteriol. 89:1109-1116. 1965.-Twenty-seven strains of Vibrio sputorum were isolated from human gingival debris. All strains reduced nitrate beyond nitrite, and all produced H(2)S. None produced catalase, indole, or acetylmethylcarbinol. Carbohydrates were not fermented, and acid end products or volatile neutral products could not be detected. Motility was observed infrequently, although 14-hr cultures usually had a few cells which displayed darting motility. Shadowed electron microscopic preparations demonstrated that most cells in a given culture were nonflagellated, although some cells with a single terminal or subterminal flagellum were always observed. V. sputorum was demonstrated not to be a strict anaerobe as previously described, but rather a microaerophile. Addition of nitrate to culture media markedly enhanced growth. V. sputorum was found to be closely related to the animal microaerophilic vibrios, V. bubulus and V. fetus. V. sputorum differed from V. fetus by being capable of anaerobic growth, producing H(2)S, and failing to produce catalase or to grow in 10% O(2). Antigens of V. sputorum cross-reacted in low titer with antisera to V. fetus serotypes I, II, III, and V. V. sputorum differed from V. bubulus by being inhibited by 3.5% NaCl and by qualitative differences in growth in the presence of 1% glycine and 10% O(2). These differences do not appear sufficient to recognize two distinct species, and it is proposed that both species be recognized as V. sputorum, which has priority. Strains unable to grow in 3.5% NaCl would be considered V. sputorum var. sputorum, whereas strains capable of growth in 3.5% NaCl would be V. sputorum var. bubulum.

SIALIDASE (NEURAMINIDASE) OF CORYNEBACTERIUM DIPHTHERIAE

Warren, Leonard (National Institute of Arthritis and Metabolic Diseases, Bethesda, Md.) and C. W. Spearing. Sialidase (neuraminidase) of Corynebacterium diphtheriae. J. Bacteriol. 86:950-955. 1963.-The characteristics of a sialidase produced by Corynebacterium diphtheriae were studied. The enzyme was partially purified from preparations of diphtheria toxin on a column of Sephadex G-75. By this means the lethal factor of diphtheria toxin was separated, in part, from the sialidase activity. There appeared to be a close immunological relationship between the sialidases of C. diphtheriae and clostridia, since a preparation of diphtheria antitoxin was as effective an inhibitor of diphtheria sialidase as of the sialidase of three species of clostridia. Conversely, antitoxin to clostridia inhibited diphtheria sialidase. Diphtheria antitoxin was essentially inactive toward influenza virus sialidase, and was completely inactive against purified sialidase of Vibrio cholerae. Removal of sialic acid from the proteins in a preparation of diphtheria antitoxin did not alter the inhibitory activity of the antitoxin against diphtheria sialidase. The enzyme operated optimally at pH 5.5 and did not require calcium ions for activity. The substrate specificity of diphtheria sialidase appears to be the same as that of other previously described sialidases.

CLINICAL EVALUATION OF TYLOSIN AS A TREATMENT OF VIBRIONIC DYSENTERY IN SWINE

A 5 year history of swine dysentery and treatment has been described.In 1964, a severe outbreak diagnosed as Vibrionic dysentery in 166 litters farrowed from January - March caused a death loss of 30.3 per cent of the total number weaned. This outbreak was not checked with an organic arsenic, sodium arsanilate, which had previously been relatively effective.A subsequent farrow of 133 litters (June - August, 1964) was infected and again sodium arsanilate was ineffective. Microscopic examination of smears of representative fecal samples revealed the presence of a heavy concentration of vibrio-like organisms. Two test-barns, housing 140 and 172 pigs respectively, were treated with tylosin-tartrate, using one side of each barn as a control, while the other side was being treated. Subsequently, the control sides were treated. Both levels of tylosin used, 1 gm and 2 gm per U.S. gallon of water, resulted in the disappearance of fluid feces within 48 hours of treatment. Soft, granular feces were still present 6-9 days after the start of treatment at the 1 gm level, while in case of the 2 gm level of tylosin, all feces were normal on the third day after medication started. Microscopic examination of feces collected on the third day of treatment still revealed the presence of some vibrio-like organisms. However, these organisms could not be detected in examination of feces collected between 10 to 25 days after treatment. In this test there was no recurrence of dysentery.