Rapid bacteriuria screening in a urological setting: clinical use.

The clinical use of a commercially available semiautomated bacteriuria screening device was evaluated in a urological setting. The 1,300 consecutive urine specimens processed by the device were contrasted with results of standard semiquantitative culture. A small number (2 per cent) were screened unsuccessfully owing to a clogged filter. With greater than 10(5) colony-forming units per ml. the sensitivity of the device was 91 per cent but it was only 81 per cent with bacteriuria levels greater than 10(4) colony-forming units per ml. More importantly, the predictive value of a negative test was 99 per cent with more than 10(5) colony-forming units per ml. and 96 per cent with more than 10(4) colony-forming units per ml. This capability promotes safe urological instrumentation and timely patient care.

Value of the L-pyrrolidonyl-beta-naphthylamide hydrolysis test for identification of select gram-positive cocci.

A 4 hr test for hydrolysis of L-pyrrolidonyl-beta-naphthylamide (PYR) was evaluated for its use in identifying group A beta-hemolytic streptococci, group D enterococci, and Staphylococcus haemolyticus. All of the group A streptococci and the enterococci tested were positive in the PYR test, whereas all of the nongroup A, B, or D beta-hemolytic streptococci, all of the viridans, and all of the Streptococcus pneumoniae isolates tested were PYR negative. Two strains of Aerococcus species were PYR positive and could not be differentiated from enterococci in this test. All strains of S. haemolyticus, a single strain of S. intermedius and two of seven strains of S. warneri were PYR positive whereas all other staphylococci tested were PYR negative. The PYR test is suitable for routine, presumptive identification of group A streptococci, group D enterococci and S. haemolyticus in the clinical laboratory.

Use of the API 20E, Oxi/Ferm, and Minitek systems to identify nonfermentative and oxidase-positive fermentative bacteria: seven years of experience.

The API 20E (API) system, the Oxi/Ferm (OXF) system, and the Minitek (MIN) system were used over a seven-year period to identify clinical isolates of nonfermentative bacteria (NFB) and oxidase-positive fermentative bacteria (OPFB). A total of 742 NFB and OPFB were tested with the API system, 988 with the OXF system, and 918 with the MIN system. The organisms represented 34 recognized species, nine alpha-numeric designates, and three species of unnamed NFB. Results were compared to those obtained with conventional test methods, which were considered correct in all instances. The accuracy of identification of NFB and OPFB was 61% with API, 80% with OXF, and 72% with MIN. Identification was more favorable for all systems with the oxidase-negative bacteria than with the oxidase-positive bacteria. API successfully identified 84% of the oxidase-negative organisms compared to 48% of the oxidase-positive organisms, OXF identified 93% compared to 75%, and MIN identified 96% compared to 61%. Failure of identification was usually a result of failure of the generated codes to appear in the compendia, rather than of misidentification, especially for the oxidase-positive organisms. The OXF system required the greatest number of supplemental tests for identification with a ratio of .65 (supplemental tests per isolate) and the API the least (.20). The API system generated the most codes with a ratio of .46 and the OXF system the fewest codes (.16).

Identification of pathogenic Neisseria species with the RapID NH system.

The RapID NH system (Innovative Diagnostics Systems, Inc., Decatur, Ga.) is a 4-h test used in the identification of Neisseria and Haemophilus species. The system was evaluated for accuracy and reliability and compared with conventional (cystine proteose peptone agar; Prepared Media Laboratory, Tualatin, Ore.) carbohydrate degradation tests with Neisseria gonorrhoeae and N. meningitidis, as well as a variety of Neisseria, Branhamella, and Moraxella species. The RapID NH system correctly identified all N. gonorrhoeae, N. meningitidis, and N. lactamica isolates, but the level of accuracy varied considerably for the remaining organisms. One strain of N. subflava was misidentified as a pathogenic Neisseria strain. The RapID NH tests were concluded in 4 h, whereas the cystine proteose peptone agar tests required up to 48 h for results to be useful. The RapID NH system is an accurate, reliable, and useful method for the identification of pathogenic Neisseria species. It has been proven that it shortens identification time and specimen turnaround time by at least 24 h.

Urea-hydrolyzing Vibrio parahaemolyticus associated with acute gastroenteritis.

A case of gastroenteritis caused by a urea-hydrolyzing strain of Vibrio parahaemolyticus is presented. Urea-hydrolyzing strains of Vibrio parahaemolyticus have rarely been reported and have not been described previously as a cause of gastroenteritis in the United States. With the exception of urea hydrolysis and the methyl red test, the isolate had all the characteristics of V. parahaemolyticus. The need to screen suspicious non-lactose-fermenting colonies from stool specimens with the oxidase test is emphasized.

Isolation and cultivation of Haemophilus ducreyi.

A useful method for isolating and recognizing Haemophilus ducreyi from chancres and buboes of male patients is presented. A total of 41 clinical isolates of H. ducreyi were recovered from 33 patients over an 8-year period, and the experience with the 15 most recent isolates is presented in detail. Chocolate agar supplemented with 1% Iso VitaleX and 5% sheep blood agar were prepared, using Trypticase soy and Mueller-Hinton Agar bases, and incubation conditions included ambient, capneic, and anaerobic environments. Mueller-Hinton agar was clearly superior over Trypticase soy agar for isolation of H. ducreyi, although there was little difference between 5% sheep blood and supplemented chocolate agar. Growth in ambient air and under anaerobiasis was poor or lacking, whereas growth in 5 to 7% CO2 was good to luxuriant. Heat-inactivated and fresh (unheated)human blood clot tubes also were used for selective isolation. Although the rates of isolation from the two types of clot tube were not significantly different, unheated clot tubes were superior to heated clot tubes because of reduced level of contaminants. Gram stain characteristics taken from blood clot tubes and solid media, cellular and colonial morphology of the bacilli, and lack of oxidase, catalase, and biochemical activity except nitrate reductase were determinant factors. The results of this study demonstrated that successful isolation of H. ducreyi can be achieved with a minimal amount of resources and expertise.

Evaluation of the rapid penicillinase paper strip test for detection of beta-lactamase.

The penicillin-starch paper strip method was compared with the acidometric and iodometric methods for assaying beta-lactamase production, using fresh isolates of clinically important bacteria. Results obtained by the three methods were compared for rapidity, accuracy, and stability of reagents. Of the 210 isolates tested by the paper strip method, 301 isolates tested by the acidometric method, and 117 isolates tested by the iodometric method, all were in perfect agreement with the disk diffusion susceptibility test except one strain each of Haemophilus influenzae, Staphylococcus aureus, and Staphylococcus epidermidis. The H. influenzae isolate was penicillin resistant and failed to give a positive test for beta-lactamase in all three tests. The staphylococci (intermediate and resistant in susceptibility, respectively) failed to give a positive test for beta-lactamase with the iodometric method. The results of the paper strip method, in which 3,241 strains representing nine species of bacteria were used, correlated completely with disk susceptibility tests except for 2 and 69 strains, respectively, of penicillin-resistant, beta-lactamase-negative H. influenzae and H. parainfluenzae. The results of this study indicate that the paper strip method is accurate, simple to perform, extremely economical, and uses materials that are stable when stored frozen. It is eminently suitable for routine laboratory use.

Characteristics of human isolates of unidentified fluorescence pseudomonads capable of growth at 42 degrees C.

Five strains of an unidentified fluorescent Pseudomonas sp. which were capable of growth at 42 degrees C were isolated over a 3-year period and were examined and compared with chosen strains of Pseudomonas aeruginosa, P. fluorescens, and P. putida. The strains were examined in a range of biochemical and carbon substrate alkalinization tests. The outstanding properties of the unidentified fluorescent Pseudomonas sp. included monopolar arrangement of flagella, gelatin liquefaction, litmus milk peptonization, and growth on cetrimide and Salmonella-Shigella agars. All strains failed to produce pyocyanin, 2-ketogluconate, and nitrogen gas, failed to acidify mannitol and xylose, and failed to alkalinize acetamide and allantoin. Similarities to P. fluorescens and P. putida were reflected in their resistance to carbenicillin and susceptibility to kanamycin and tetracycline.

Characteristics and biotypes of Pasteurella multocida isolated from humans.

Fifty-two isolates of Pasteurella (48 strains of Pasteurella multocida and 4 strains of atypical Pasteurella) were identified by conventional and commercial test systems. All strains fermented glucose, sucrose, and fructose in purple broth base (Difco Laboratories) with bromocresol purple as indicator, although the atypical Pasteurella produced fermentation reactions that were barely perceptible. Eleven different biotypes were identified by fermentation reactions in maltose, mannitol, xylose, sorbitol, and trehalose media. There was a correlation of biotypes to cat bites, with 61% of cat bite isolates falling into biotype A and B. A correlation of biotype and dog bite isolates was not seen. The choice of medium used for fermentation tests was critical as evidenced by the inability of the organisms to grow in a second commercially purchased preparation of purple broth base. The reliability of commercial test systems in identifying Pasteurella was 81% for Oxi/Ferm (Roche Diagnostics, Div. Hoffmann-La Roche, Inc., Nutley, N.J.), 68% for API (Analytab Products, Plainview, N.Y.), and 11% for Minitek (BBL Microbiology Systems, Cockeysville, MD.).

Cultural and biochemical characteristics of clinical isolates of unusual colistin-resistant pseudomonads.

Biochemical characteristics and antibiotic susceptibilities of 12 strains of colistin-resistant pseudomonads isolated from clinical specimens are reported. The isolates were short, oxidase-positive, nonfluorescing, gram-negative rods that failed to grow on salmonella-shigella or cetrimide agars, to decarboxylate amino acids, and to reduce nitrates. Most strains peptonized litmus milk and grew at 42 degrees C. Glucose, lactose, maltose, xylose, and fructose were slowly oxidized, whereas sucrose was not. Two homogeneous species were found and tentatively listed as Pseudomonas sp. 1 and Pseudomonas sp. 2, and these were differentiated by gelatin and starch hydrolysis, oxidation of mannitol, and alkalinization of allantoin. The two species were shown to differ from the Center for Disease Control Va group biotype CDC Va-1 in both biochemical characteristics and susceptibility to the aminoglycosides.

Yersinia pseudotuberculosis: use of cold-temperature enrichment for isolation.

The successful isolation of Yersinia pseudotuberculosis from the stool of an asymptomatic family member of a patient with yersinia septicemia is presented. Cold enrichment permitted the isolation after 4 weeks of refrigerator incubatio,.

Growth of nonfermentative bacteria at 42 degrees C.

Growth at 42 degrees C is advocated to differentiate species of the fluorescent pseudomonas group as well as to differentiate other nonfermentative bacteria. Methodologies vary in the performance of the test, resulting in differing and often discrepant results between investigators. During this evaluation, the test was performed by inoculating 3 ml of Trypticase soy broth with a loopful of an overnight broth culture. Growth in the 42 degrees C tube was judged as heavy or slight after 24 and 48 h incubation at 41.5 +/- 0.5 degrees C. Pseudomonas aeruginosa grew abundantly after overnight incubation, whereas 16 of 74 isolates of P. putida (22%) showed slight turbidity in the broth after 24 or 48 h which could not be regarded as an inoculum effect. Trypticase soy agar was used in conjunction with Trypticase soy broth, with the growth again judged as heavy or slight. Growth of P. putida on slants was still seen in some cases (6%) although the number of strains showing growth had declined. Triphenyltetrazolium chloride was added to Trypticase soy broth (0.005%) as a color indicator of growth. Strains of P. putida, although showing visible evidence of growth, gave no color change when compared with the 35 degrees C control. The constancy in test results using nonfermentative bacteria is not only method dependent but also strain dependent. Although the test for growth at 42 degrees C is important as a taxonomic tool when used under controlled conditions, other tests such as acetamide are preferred as a substitute for use in the clinical laboratory.

Antibiotic susceptibilities of human isolates of Pasteurella multocida.

Seventeen human strains of Pasteurella multocida, biochemically similar to, if not identical with, isolates of animal origins, were tested for susceptibility to 16 antimicrobial agents utilizing a microtiter broth dilution technique. Ten of these isolates were also tested against 11 antibiotics by disk diffusion. The most active drugs with respect to the median minimal inhibitory concentration (micrograms per milliliter) were tetracycline (0.09), penicillin G (0.78), ampicillin (0.78), carbenicillin (1.56), cephalothin (1.56), and chloramphenicol (1.56). With the exception of tetracycline, the median minimal inhibitory concentration and minimal bactericidal concentration values were equal or differed by no more than a factor of two. The semisynthetic penicillins clindamycin, erythromycin, and aminoglycosides had relatively low activities, suggesting that these agents would be poor choices for the treatment of P. multocida infections.

Biotypes of Haemophilus encountered in clinical laboratories.

The biochemical characteristics of 464 strains of Haemophilus influenzae and 83 strains of Haemophilus parainfluenzae isolated over an 18-month period are described. Of 22 characteristics obtained, only 6 were necessary to biochemically identify and biotype the isolates. The key substrates or tests were urease, ornithine, indole, o-nitrophenyl-beta-D-galactopyranoside, sucrose, and xylose. Five biotypes of H. influenzae and four of H. parainfluenzae were commonly recognized. Some strains were encountered which could not be accommodated in the recognized taxa but which constituted separate biotypes of the two species, H. influenzae biotype I was recovered principally from blood, cerebrospinal fluid, and upper respiratory secretion, and biotypes II and III were recovered from eye and sputum cultures. Biotype I was recovered primarily from children less than 1 year of age, whereas biotypes II and III were from persons 1 to 5 years old and from those over 20 years of age. Multiple isolates recovered from the same patient were almost always of the same biotype. Strains of H. parainfluenzae were isolated primarily from sputum, with others being isolated from body sources such as dental abscesses, gastric aspirates, and peritoneal fluid. An inverse relationship was noticed between hemolysis and mannose fermentation among H. parainfluenzae biotype III strains, whereas the relationship was absent among the other biotypes.

Comparison of the API 20E and Oxi/Ferm systems in identification of nonfermentative and oxidase-positive fermentative bacteria.

The API 20E and Oxi/Ferm systems were tested in parallel to identify nonfermentative bacteria and oxidase-positive fermentative bacteria. Test strains consisted of consecutive clinical isolates, with stock cultures used to supplement those species infrequently recovered. The two microsystems, as well as tubes of triple sugar iron, motility, cetrimide, and oxidative glucose media, were inoculated by each worker for each organism. Identification of each isolate was by the protocol of the manufacturers, with supplemental tests and flagella stains performed when necessary. Concurrent identification was undertaken with a conventional system against which the results of the two systems were compared for accuracy. There was a 95.3% accuracy in identification by the Oxi-Ferm system and 88.9% by the API system. Almost one-fourth of all identification attempts with the API required computer assistance, and most of these were for oxidase positive bacteria. Because of this, and because the API system showed greater accuracy in identification of the oxidase-negative bacteria, it seems best suited for identification of these organisms (P. maltophilia, A. anitratus, and A. lwoffi). The Oxi/Ferm system is technically less cumbersome than the API and is well suited for both groups of organisms.

Use of the Minitek system for biotyping Haemophilus species.

The Minitek system was used for characterization and identification of Haemophilus. The system was simple to use and provided rapid and clear-cut test results.

Evaluation of the oxi/ferm tube system with selected Gram-negative bacteria.

The Oxi/Ferm test system was evaluated for accuracy and reliability for identification of nonfermentative and oxidase-positive fermentative bacteria by using 375 bacterial strains obtained from stock culture and clinical specimens. The Oxi/Ferm system is a compartmentalized tube containing eight media to provide nine biochemical test results. When combined with the oxidase test, the results corresponding to the positive reactions are totaled and the composite number is located in the coding manual to identify the organisms. The 375 isolates studied were evaluated for accuracy of identification, using both the original and revised code manuals. In comparison with the conventional media used, there was 100% correlation in tests for hydrogen sulfide and indole production, over 96% for nitrogen gas, arginine, and urease, over 92% for xylose and dextrose oxidation, and less than 90% for citrate utilization and dextrose fermentation. There was an overall accuracy in identification of 89.3% using the original manual, with accuracy revised slightly upward to 90.7% using the revised manual. There was 100% accuracy in identification with 44.0% of the strains tested (11 species) using the original manual and with 66.1% (16 species) using the revised manual. Thirteen of the 40 original misidentifications and 14 of 35 revised misidentifications resulted from failure to code and were unidentifiable by Oxi/Ferm. The remainder were incorrectly identified or could not be differentiated from closely related strains. Eleven strains of Alcaligenes odorans were correctly identified using the original code, whereas no code was provided in the revised manual. The Oxi/Ferm system is both simple and rapid and is satisfactory for identification of the more common isolates.

Characterization and identification of gram-negative, nonfermentative bacteria.

The morphological and physiological characteristics of 593 strains of nonfermentative, gram-negative bacteria are described. A battery of 46 tests was used to identify and differentiate strains representing 8 genera and 31 species of named and group-designated bacteria. Seven selected amides and organic salts were closely examined to determine their usefulness, individually or as a battery, in characterizing and identifying the organisms. Of these, allantoin and acetamide showed the most promise in differentiating the more commonly occurring organisms from biochemically similar species. Susceptiblilty patterns to 12 antimicrobics also proved useful in differentiation, especially among atypical strains.

Evaluation of the rapid decarboxylase and dihydrolase test for the differentiation of nonfermentative bacteria.

A rapid medium for the detection of lysine and ornithine decarboxylase and arginine dihydrolase activity of 439 strains of gram-negative, nonfermenting bacteria was evaluated and compared with Moeller decarboxylase medium. Results were obtained in 4 to 24 h using the rapid medium, whereas Moeller medium often required extended (3 to 7 days) incubation. There was 100% agreement in the lysine tests with both media and almost 100% agreement in the ornithine tests. There was 91% agreement in the arginine tests, with the significance of discrepant results discussed. The sensitivity, specificity, and quick results obtained by the rapid test make it a suitable substitute for Moeller medium for the identication of gram-negative, nonfermenting bacteria.

Seroimmunity to poliomyelitis in an American community.

In an effort to determine the immune status of individuals in a natural community, neutralizing antibody titers for the three types of poliovirus were examined in 301 randomly sampled sera collected in 1966 and 308 specimens from 1971. The specimens were part of a larger collection obtained from residents of Tecumseh, Michigan. Approximately 22 sera from each five-year age group between 5-70 years were tested. A somewhat smaller number from younger and older individuals were also studied. Geometric mean titers for the two years of collection were in general quite low and never exceeded 1:42 which was found for type II virus. All GM titers decreased markedly as the age of the subjects increased. The percentage of individuals lacking antibody at the 1:4 level to at least one type of poliovirus ranged between 20-30% until age 49 and then steadily increased to over 60% in the 60-69 and over 70-year groups. A retrospective history of vaccination was obtained from 264 of the 308 persons in the 1971 collection. As expected these showed rather poor correlation with the presence or absence of antibody and were considered to be unsatisfactory as an index of immunity.