Rapid presumptive identification of vibrios by immobilization in distilled water

Characterization of bacteria in ballast water using MALDI-TOF mass spectrometry

To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time.

Feasibility of same-day identification of members of the family Vibrionaceae by the API 20E system

Sixty isolates, comprising nine species of the family Vibrionaceae, were tested with the API 20E 5-h same-day procedure (Analytab Products, Plainview, N.Y.). Included were 27 Aeromonas hydrophila isolates, 10 Aeromonas sobria isolates, 7 Aeromonas caviae isolates, 3 Plesiomonas shigelloides isolates, 3 Vibrio alginolyticus isolates, 3 Vibrio cholerae isolates, 1 Vibrio fluvialis isolate, 5 Vibrio parahaemolyticus isolates, and 1 Vibrio vulnificus isolate. The 5-h profile numbers were specific for the five Vibrio species and the Plesiomonas isolates. The three Aeromonas species shared seven 5-h profile numbers. Of the 63 5-h profile numbers generated by testing each isolate twice, 22 were identical to those found in the overnight analytical profile index. Of these, 20 were correct identifications, and two were incorrect. The remaining 41 5-h profile numbers were not found in the overnight analytical profile index. Because the 5-h analytical profile index does not contain any oxidase-positive organisms, the oxidase value was subtracted from the 63 5-h profile numbers to determine whether misidentifications could occur if the oxidase test was either not performed or not performed correctly. Only five of these factored profile numbers resulted in a possible misidentification. It is feasible, within limitations, to use the 5-h API 20E same-day procedure to identify the more commonly occurring members of the Vibrionaceae. The manufacturer should develop a data base for this purpose.

Comparison of API 20E, API rapid E, and API rapid NFT for identification of members of the family Vibrionaceae

Sixty isolates, from nine species of the family Vibrionaceae, were tested by the API 20E, API Rapid E, and API Rapid NFT systems. Results were compared with those obtained with standard biochemicals. Included were 7 Aeromonas caviae isolates, 27 Aeromonas hydrophilia isolates, 10 Aeromonas sobria isolates, 3 Plesiomonas shigelloides isolates, 3 Vibrio alginolyticus isolates, 3 Vibrio cholerae isolates, 1 Vibrio fluvialis isolate, 5 Vibrio parahaemolyticus isolates, and 1 Vibrio vulnificus isolate. The API 20E correctly identified all the isolates within 24 h. The API Rapid E correctly identified only 77%, misidentified 8%, and failed to identify 2% of the isolates in 4 h. The remaining 13% of the isolates gave a low selectivity identification, with one of the choices being correct. The API Rapid NFT correctly identified 87%, misidentified 5%, gave a low selectivity identification for 8% of the isolates, and in some instances, required up to 48 h of incubation. The API 20E is a valid system for use in the identification of the more commonly occurring members of the family Vibrionaceae and the most accurate and efficient of the three systems tested.

Growth of non-Campylobacter, oxidase-positive bacteria on selective Campylobacter agar

A total of 67 oxidase-positive, gram-negative bacteria were tested for growth on selective Campylobacter agar (Blaser formulation, BBL Microbiology Systems, Cockeysville, Md.) at 42 degrees C under microaerophilic conditions. Although the growth of most of these bacteria was prevented, all strains of Achromobacter xylosoxidans, Pseudomonas aeruginosa, Pseudomonas putrefaciens, Pseudomonas alcaligenes, and Pseudomonas pseudoalcaligenes grew as well as Campylobacter fetus subsp. jejuni.

Dark-field microscopy of human feces for presumptive diagnosis of Campylobacter fetus subsp. jejuni enteritis

To determine the value of direct dark-field microscopy for diagnosing enteritis due to Campylobacter fetus subsp. jejuni, we examined 1,377 human fecal specimens for bacteria with typical Campylobacter darting motility, leukocytes, and erythrocytes. Eighty-four specimens (6.1%) grew C.fetus subsp. jejuni. Of the 48 specimens showing Campylobacter motility, 30 (62%) grew C. fetus subsp. jejuni. The sensitivity, specificity, and predictive value of observing Campylobacter motility were 36%, 99%, and 62%, respectively. The predictive value of detecting Campylobacter motility was improved if the specimens were diarrheal (23 of 31, 74%), leukocytes were present (25 of 33, 76%), erythrocytes were present (22 of 27, 81%), or if all of the above findings were present (18 of 20, 90%). The sensitivity of detecting Campylobacter darting motility was highest if specimens were examined within 2 h of arrival in the laboratory (15 of 30, 50%) as opposed to after 2 h (15 of 53, 28%; P less than 0.01). Prompt dark-field microscopic examination of diarrheal stool specimens is valuable for the presumptive diagnosis of Campylobacter enteritis.