Corynebacterium nigricans sp. nov.: Proposed Name for a Black-Pigmented Corynebacterium Species Recovered from the Human Female Urogenital Tract

Abstract

Six independent isolates of an unusual black-pigmented Corynebacterium species (strains CN-1, CN-2, CN-3415, W70124, 91-0032, and 92-0360) were recovered from the human female urogenital tract. Four of the six source patients had complications of pregnancy, including spontaneous abortion, preterm labor, and low amniotic fluid volume at the time of the pathogen isolation. One isolate was recovered from a vaginal ulcer. All six strains yielded black-pigmented colonies on sheep blood agar, chocolate agar, and colistin-nalidixic acid agar after 24 to 48 h of incubation at 35°C. The dry, adherent colonies pitted the agar surface. The cells were coccobacillary to rod-shaped, catalase positive, nonmotile, and nonlipophilic. Only five of six isolates were available for characterization. Biochemical and chemotaxonomic studies revealed that the strains belong to the genus Corynebacterium but differ from known corynebacterial species. Comparative 16S rRNA gene sequence analysis showed that the strains are closely related and form a new subline within the genus Corynebacterium. We propose the name Corynebacterium nigricans sp. nov. for this group of coryneforms. The type strain of Corynebacterium nigricans is CN-1. It is deposited in the American Type Culture Collection (assigned strain number ATCC 700975) and in the Institute Pasteur collection (assigned strain number CIP 107346).The female urogenital tract is a natural habitat for a multitude of commensal microbes, including diphtheroids. In many instances, these microbes and their metabolites serve as barriers against colonization by harmful pathogens that may cause different diseases. The reported commensal organisms of the female urogenital tract are species of Lactobacillus, Staphylococcus, Streptococcus, Neisseria, Mycoplasma, Ureaplasma, enteric organisms, Acinetobacter, Capnocytophaga, Enterococcus, Bacteroides, Porphyomonas, Prevotella, Fusobacterium, Mobiluncus, Peptostreptococcus, Propionibacterium, Actinomyces, Bifidobacterium, Candida, and coryneform bacteria (8). Like other resident microbes of the human body, some of the vaginal microbiota also are opportunistic pathogens, which become pathogenic when the host immune status is compromised, suppressed, or under immunologic stress. A number of bacterial species are associated with urogenital-related diseases, and among the Corynebacterium species, C. lipophiloflavum, C. amycolatum, C. glucuronolyticum, C. riegelii, and C. urealyticum have been implicated (4, 6-8). The CDC coryneforms group 4 and C. lipophiloflavum are reported to cause urinary tract infections and bacterial vaginosis, respectively (5, 9).Through the use of nucleic acid-based detection and characterization methods, such as 16S rRNA gene sequence analysis, many new pathogenic organisms are continually being identified, characterized, and linked to diseases of known and unknown etiology. This approach has been successfully applied in our laboratory to identify and characterize a number of fastidious microorganisms (12,(15)(16)(17)). An unusual ...

Identification of Some Charcoal-Black-Pigmented CDC Fermentative Coryneform Group 4 Isolates asRothia dentocariosaand Some asCorynebacterium aurimucosum: Proposal ofRothia dentocariosaemend. Georg and Brown 1967,Corynebacterium aurimucosumemend. Yassin et al. 2002, andCorynebacterium nigricansShukla et al. 2003 pro synon.Corynebacterium aurimucosum

“…Rothia-like FCG4a ATCC BAA-907 was positioned with R. dentocariosa with 100% similarity. Corynebacterium-like FCG4b strain ATCC 700540 (CDC B8037) was positioned in a group with C. aurimucosum, C. nigricans, C. singulare, C. minutissimum, and two sequences from uncultured Corynebacterium-like organisms, strains MTcory1P and MTcory16R, which were similar to those given by Yassin et al (21) and Shukla et al (13). A similarity matrix (Table 3) cariosa.…”

“…A small amount (Յ6%) of tuberculostearic acid (10-CH 3 -C 18:0 ) was detected in 23 Corynebacterium-like FCG4b strains, of which all but one contained Յ3%, while strain G6250 contained 6%. CFA profiles of strains that contained tuberculostearic acid were more closely related to C. minutissimum, C. aurimucosum (21), or C. nigricans (13), whereas strains that did not contain tuberculostearic acid had CFA profiles more closely related to those of C. matruchotii, C. amycolatum, or C. singulare (11).…”

“…This profile was characterized by the presence of major amounts of a-C 15:0 (22 to 43%), i-C 16:0 (7 to 14%), C 16:0 (9 to 23%), a-C 17:0 (11 to 20%), C 18:2 (6 to 11%), and C 18:1T9c (4 to 12%). The remaining 37 strains (Table 1) (Corynebacterium-like FCG4b) produced a CFA profile similar to the profile of C. matruchotii, C. amycolatum, C. minutissimum, C. aurimucosum (21), C. singulare (11), and C. nigricans (13). This profile was characterized by major amounts of C 16:0 (33 to 47%), C 18:1T9c (37 to 54%), and C 18:0 (4 to 12%).…”

An Improved DNA Isolation Method for Metagenomic Analysis of the Microbial Flora of the Human Intestine

“…Enterococcus gallinarum CKY was cultivated in 10 ml of MRS liquid medium at 37°C for 18 h. The other strains, Escherichia coli AE1-2, Staphylococcus pasteuri AE4H, Corynebacterium nigricans AE1-3, and Bacillus subtilis AE4-3, were incubated with shaking in 10 ml of LB liquid medium at 37°C for 16 h. Corynebacterium nigricans were isolated from the stool sample of the father grown on the Schaeffer spore-forming agar medium (Table 2). Although first isolated from the female urogenital tract, which is a natural habitat for a multitude of commensal microbes 14) , C. nigricans may be a commensal organism that resides not only in the female urogenital tract but also in the human intestine, since this species was isolated from the fecal sample of one of the males in the present study. The 16S rDNA sequence of strain AE4H isolated from the samples obtained from the 22-month-old boy and grown on slightly modified HA medium that contained 20% NaCl showed 99% similarity to Staphylococcus pasteuri, which was originally isolated from humans and animals, as well as from food specimens 3) .…”

CorynebacteriumSpecies Isolated from Bone and Joint Infections Identified by 16S rRNA Gene Sequence Analysis

“…Our three isolates did not produce black pigment. On the basis of 16S rDNA sequence analysis, overlapping of positions for C. aurimucosum and C. nigricans strains has been observed (21). Further studies (including DNA-DNA hybridizations and large collections of strains) will have to be done to ensure that this black pigmentation is a constant feature for the characterization of C. nigricans species.…”