Biochemical properties of group G streptococci isolated from cats and man.

The biochemical characteristics of group G streptococci isolated from cats were markedly similar to the characteristics of group G streptococci from man. Both cat and human isolates of group G streptococci were also very similar in biochemical characteristics to group A streptococci so that to identify the source of group G streptococci by biochemical reactions is not a reliable procedure. The group G streptococci found in many cats could be pathogenic to man, since their physiological and biological characteristics are very similar to those of group A streptococci.

Behavior of Vibrio cholerae in hot foods.

Four food types held hot at 45 to 60 degrees C were deliberately contaminated with O1 and non-O1 Vibrio cholerae strains. These organisms were assayed for survival and recovery from the foods within 1 h of the time the food was kept hot. The results showed no growth of V. cholerae non-O1 on thiosulfate-citrate bile-sucrose agar plates after 24 h of incubation at 37 degrees C for food held hot at 50 to 60 degrees C. Growth was low for V. cholerae O1 and was not achieved in some instances in which foods were held at either 55 or 60 degrees C after 40 or 60 min of from the time the food was kept hot. Both organisms, however, were recovered equally from all food types held at all temperatures after 48 h of incubation. When incubated for an additional 24 h, the organisms grew to unusually small-sized colonies, measuring 0.1 to 0.3 mm in diameter, on the same agar plates that were negative for growth after an initial 24 h of incubation. It was concluded that V. cholerae survived the period of time held at hot temperatures. Although the organisms were not recovered from some foods when held at some of the temperatures and times after 24 h of incubation, they remained viable. An incubation period of 48 h at 37 degrees C was found to be appropriate for the recovery of V. cholerae from hot foods.

Effects ofFlavobacterium lutescens growth on populations ofEscherichia coli andStreptococcus faecalis in water following thermal loading.

Flavobacterium lutescens has been observed to constitute a major segment of the aerobic, heterotrophic bacterial populations in nonpolluted aquatic systems. It is present in lesser numbers in the presence of municipal sewage and higher concentrations of organic wastes. In laboratory tests, in water from nonpolluted systems, this species became the predominant bacterial type following thermal addition. When temperature was increased in water from polluted sources,F. lutescens became a major component of the bacterial populations. In the laboratory, the numbers ofEscherichia coli andStreptococcus faecalis were observed to decrease in proportion to the increase inF. lutescens after thermal addition. Similar results were observed when water from three aquatic systems of differing nutrient content was tested. A greater amount of organic material present in the water reduced the predominance ofF. lutescens. These results indicate that, without use of chemical additives, this method may be useful for restoration of natural aquatic bacterial populations and reduction of undesirable microbial populations in water supplies.

Membrane filter-fluorescent-antibody method for detection and enumeration of bacteria in water.

A technique which employs nonfluorescing membrane filters and specific fluoresceinisothiocynate-labeled antiserum has been successfully used in the identification and enumeration of known species of Escherichia coli which have been added to natural populations of bacteria found in water. The quantitative results compared favorably with those of standard tests. The use of a dissecting microscope with an external lighting arrangement provided a simple requirement for equipment. This method may be useful in monitoring specific bacterial types from waters which were being monitored for specific pollution.

The occurrence of nicotinamide adenine dinucleotide glycohydrolase and the serum opacity reaction in groups B, C, F and G streptococci.

The frequency of the serum opacity reaction (SOR) and nicotinamide adenine dinucleotide glycohydrolase (NADase) production in non-A groups of beta-haemolytic streptococci isolated from humans and animals was surveyed. The SOR was positive with five of eighteen group B isolates (28%), four of fifteen group C (27%), two of five group F (40%), and thirty-seven of sixty-eight group G (54%) isolates. NADase activity, in addition to SOR, was found in three of eighteen group B isolates (17%), three of fifteen group C (20%), forty of sixty-eight group G (59%), and none of the group F isolates. The SOR was produced by forty-eight (45%) and NADase was produced by fifty-one (48%) of the one hundred and six isolates of non-group A beta-haemolytic streptococci. Twenty-five percent of the isolates were both NADase and SOR positive.

Multiplication in human blood and deoxyribonuclease production by group G streptococci isolated from animals and humans.

An M protein or an M protein-like substance was found to be present in a large proportion of group G streptococci isolated from animals and humans. Forty-seven percent of the isolates from cat throats and 38% of the isolates from the vagina of cats were able to multiply in human blood. Only 14% of the human isolates of group G isolated from various anatomical sites and sources were able to multiply in fresh human blood. Deoxyribonuclease was produced by 81% of cat vagina isolates, by 80% of cat throat isolates and by only 27% of the group G isolates from humans. Thirty-five percent of the cat isolates but only 5% of the human isolates were able to both grow in blood and produce DNase.

Serological analysis of morphologically and biochemically similar Streptomyces species.

Descriptions of morphological and biochemical characteristics of Streptomyces species have resulted in groups of isolates which appear to be identical or very closely related. Serological analysis has been used to confirm this relationship in some cases and to demonstrate differences in others.

A selective-differential medium for detection of Streptococcus agalactiae.

A practical culture medium which allows direct plating of milk samples for detection and differentiation of Streptococcus agalactiae within 48 hours is described. Most other micro-organisms likely to be present in these samples are inhibited. Although some strains of Staphylococcus species and ofStreptococcus faecalis are able to grow, they may be differentiated on the basis of reaction in the medium surrounding the colonies.

Clinical significance of coagulase-negative staphylococci.

Although coagulase-negative staphylococci (C-NS) have been implicated in certain human infections, they are generally regarded as contaminants, and their clinical significance is questioned. To assess their role as pathogens, we studied 205 isolates of C-NS from wounds and body fluids (blood, urine, pleural and peritoneal fluids, etc.). Patient's charts were reviewed, and, by using strict criteria, a determination was made regarding the clinical significance of these isolates. The organisms were then identified to determine whether certain species of C-NS were associated with specific infections. S epidermidis sensu stricto accounted for 81% of the C-NS isolated. The frequencies of other species were: S. haemolyticus (6%), S. hominis (5%), S. capitis (4%), S. warneri (3%), and others (1%). Only two isolates were novobiocin resistant; neither was identified as S. saprophyticus. By using our criteria, 22% of the C-NS were considered to be clinically significant, and the majority of these (93%) was S. epidermidis. The most common source of the clinically relevant C-NS isolates was wounds. These data suggest that identification of C-NS species other than S. epidermidis may be of limited value in predicting clinical significance.