We present the first report of community-acquired human infections with marine mammal–associated Brucella spp. and describe the identification of these strains in two patients with neurobrucellosis and intracerebral granulomas. The identification of these isolates as marine mammal strains was based on omp2a sequence and amplification of the region flanking bp26 .

Yersinia pestis, the infamous plague-causing pathogen, appears to have emerged in relatively recent history. Evidence of this fact comes from several studies that document a lack of nucleotide diversity in the Y. pestis genome. In contrast, we report that variable-number tandem repeat (VNTR) sequences are common in the Y. pestis genome and occur frequently in gene coding regions. Larger tandem repeat arrays, most useful for phylogenetic analysis, are present at an average of 2.18 arrays per 10 kbp and are distributed evenly throughout the genome and the two virulence plasmids, pCD1 and pMT1. We examined allelic diversity at 42 chromosomal VNTR loci in 24 selected isolates (12 globally distributed and 12 from Siskiyou County, Calif.). Vast differences in diversity were observed among the 42 VNTR loci, ranging from 2 to 11 alleles. We found that the maximum copy number of repeats in an array was highly correlated with diversity (R ‫؍‬ 0.86). VNTR-based phylogenetic analysis of the 24 strains successfully grouped isolates from biovar orientalis and most of the antiqua and mediaevalis strains. Hence, multiple-locus VNTR analysis (MLVA) appears capable of both distinguishing closely related strains and successfully classifying more distant relationships. Harnessing the power of MLVA to establish standardized databases will enable researchers to better understand plague ecology and evolution around the world.

Francisella tularensis, the etiological agent of tularemia, is found throughout the Northern hemisphere. After analyzing the F. tularensis genomic sequence for potential variable-number tandem repeats (VNTRs), we developed a multilocus VNTR analysis (MLVA) typing system for this pathogen. Variation was detected at six VNTR loci in a set of 56 isolates from California, Oklahoma, Arizona, and Oregon and the F. tularensis live vaccine strain. PCR assays revealed diversity at these loci with total allele numbers ranging from 2 to 20, and Nei's diversity index values ranging from 0.36 to 0.93. Cluster analysis identified two genetically distinct groups consistent with the current biovar classification system of F. tularensis. These findings suggest that these VNTR markers are useful for identifying F. tularensis isolates at this taxonomic level. In this study, biovar B isolates were less diverse than those in biovar A, possibly reflecting the history of tularemia in North America. Seven isolates from a recent epizootic in Maricopa County, Ariz., were identical at all VNTR marker loci. Their identity, even at a hypervariable VNTR locus, indicates a common source of infection. This demonstrates the applicability of MLVA for rapid characterization and identification of outbreak isolates. Future construction of reference databases will allow faster outbreak tracking as well as providing a foundation for deciphering global genetic relationships.

We reviewed laboratory, clinical, and epidemiologic data on 35 patients from whom organisms belonging to the genus Roseomonas, a pink-pigmented gram-negative coccobacillus, were isolated over a 22-year period (1972-1994). Roseomonas strains were most commonly isolated from middle-aged women with one of several underlying conditions, including cancer and diabetes. Roseomonas was most commonly isolated from the blood, in association with clinical signs of sepsis. Approximately 60% of all isolates were judged to be of possible clinical significance, either as primary or secondary pathogens; 75% of all strains were recovered in pure culture. Roseomonas gilardii was the most frequently isolated species and was significantly associated with septicemia and underlying immunocompromised conditions; the species of 29% of all Roseomonas isolates could not be unequivocally identified with presently available differential tests. Genomospecies 5, currently an unnamed taxon within the genus Roseomonas, was primarily recovered as a commensal from young adults attending a sexually transmitted diseases clinic. The findings suggest that although this genus appears to have an overall low pathogenic potential for humans, Roseomonas species-in particular, R. gilardii-may be significant pathogens in persons with underlying medical complications.

Burkholderia gladioli has only recently been reported to be a human pathogen. Four cases of B. gladioli infection (including bacteremia, pneumonia, and cervical adenitis) in two adults and two young children are reported. Three of these four patients were severely immunocompromised. Commercial systems were frequently unable to identify this bacterium correctly. Antimicrobial susceptibility patterns indicated that B. gladioli strains were susceptible to the quinolones, aminoglycosides, and imipenem. In vitro laboratory investigations demonstrated that B. gladioli strains were susceptible to complement-mediated lysis of pooled human serum, thus implying that healthy individuals should be immune to infection. These four cases together with three previously reported cases suggest that B. gladioli primarily causes disease in severely immunocompromised individuals. The lack of mortality associated with infection, coupled with susceptibility to serum and lack of recognizable virulence-associated factors, suggests that this species has a low pathogenic potential.

We retrospectively analyzed epidemiologic information associated with 22 cultures of Neisseria elongata subsp. nitroreducens (formerly CDC group M-6) submitted to the Microbial Diseases Laboratory, California Department of Health Services, Berkeley, over a 16-year period. The most common illnesses noted with this bacterium were endocarditis, bacteremia, and osteomyelitis. Risk factors associated with N. elongata subsp. nitroreducens infections included dental manipulations and/or a previous history of endocarditis, valve damage, or rheumatic heart disease. The genus Neisseria is presently composed of 10 distinct species, only two of which are primary pathogens of humans (4). The preeminent pathogen of this group is N. gonorrhoeae, one of the leading causes of sexually transmitted disease in the United States and responsible for thousands of cases of acute urethritis in males and endocervical infections in females on an annual basis. The other major pathogen of this genus is N. meningitidis, a common cause of meningitis and invasive disease in children under 2 years of age, in military recruits, and in persons with severe deficiencies in the latter components (C5 to C9) of the complement pathway. The other eight neisserial species have only sporadically been associated with human illness and are generally regarded as saprophytic microorganisms under most circumstances.

Ninety-two strains of Yersinia pestis recovered over a 21-year period were evaluated for susceptibility to traditional and newer antimicrobial agents. In vitro resistance was noted only against rifampin and imipenem (ϳ20% of strains). The most active compounds (MIC at which 90% of the isolates tested are inhibited) against Y. pestis were cefixime, ceftriaxone, trimethoprim-sulfamethoxazole, and trovafloxacin.

Twenty-two strains of Edwardsiella representing the three currently recognized species were evaluated for surface characteristics and ultrastructural morphology. All isolates tested possessed a high surface cell charge as detected by DEAE-cellulose chromatography; surface hydrophobicity was variable and strain but not species dependent. Two major types of adhesins detected by hemagglutination assays were identified: one was inhibited by D-mannose (mannose-sensitive hemagglutinin) and found on all three species, and a second was not inhibited by D-mannose (mannose-resistant hemagglutinin) and was principally associated with Edwardsiella tarda. The results of physiologic and ultrastructural studies suggest that both hemagglutinins are afimbrial adhesin proteins. The results of these studies suggest that there are a number of distinct surface and ultrastructural properties associated with each of the three Edwardsiella species.