Kingella Species Research Articles

Phylogenomic analysis of the understudied Neisseriaceae species reveals a poly- and paraphyletic Kingella genus.

Taxonomic classification and phylogenetic analysis of the Neisseriaceae family have focused on the pathogens Neisseria meningitidis and Neisseria gonorrhoeae. Less is known about the relationships of commensal Neisseria species and other Neisseriaceae genera, raising the possibility that the phylogeny of this family may not agree with current taxonomy. In this study, we used available nucleotide sequences and a phylogenetic approach to assess the Kingella genus and its relatives. We found that this genus is both paraphyletic and polyphyletic. Kingella potus is more closely related to Neisseria bacilliformis than to other Kingella species. The Alysiella and Simonsiella genera form a distinct clade within the Kingella genus that is closely related to the pathogens K. kingae and K. negevensis. We find a phylogenetic relationship between Conchiformibius, Alysiella, Simonsiella, and Kingella, which we name the CASK clade. Finally, we define the gene sets that differentiate each genus of the CASK clade from one another and from the rest of the Neisseriaceae family. IMPORTANCE Understanding the evolutionary relationships between the species in the Neisseriaceae family has been a persistent challenge in bacterial systematics due to high recombination rates in these species. Previous studies of this family have focused on Neisseria meningitidis and N. gonorrhoeae. However, previously understudied Neisseriaceae species are gaining new attention, with Kingella kingae now recognized as a common human pathogen and with Alysiella and Simonsiella being unique in the bacterial world as multicellular organisms. A better understanding of the genomic evolution of the Neisseriaceae can lead to the identification of specific genes and traits that underlie the remarkable diversity of this family.

Acquisition, co-option, and duplication of the rtx toxin system and the emergence of virulence in Kingella

The bacterial genus Kingella includes two pathogenic species, namely Kingella kingae and Kingella negevensis, as well as strictly commensal species. Both K. kingae and K. negevensis secrete a toxin called RtxA that is absent in the commensal species. Here we present a phylogenomic study of the genus Kingella, including new genomic sequences for 88 clinical isolates, genotyping of another 131 global isolates, and analysis of 52 available genomes. The phylogenetic evidence supports that the toxin-encoding operon rtxCA was acquired by a common ancestor of the pathogenic Kingella species, and that a preexisting type-I secretion system was co-opted for toxin export. Subsequent genomic reorganization distributed the toxin machinery across two loci, with 30-35% of K. kingae strains containing two copies of the rtxA toxin gene. The rtxA duplication is largely clonal and is associated with invasive disease. Assays with isogenic strains show that a single copy of rtxA is associated with reduced cytotoxicity in vitro. Thus, our study identifies key steps in the evolutionary transition from commensal to pathogen, including horizontal gene transfer, co-option of an existing secretion system, and gene duplication.

Kingella pumchi sp. nov., an organism isolated from human vertebral puncture tissue.

A Gram-negative, non-motile rod and strictly aerobic bacterium, designated as 18B16333T, was isolated from vertebral puncture tissue of a patient at Peking union medical college hospital in China. Growth occurred in NaCl concentrations of 0-1% (w/v) (optimum growth at 0% NaCl), at temperatures of 25-40°C (optimum growth at 37°C) and at pH 6.0-9.0 (optimum growth at pH 8.0). Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were the predominant polar lipids, and the major fatty acids were C16:0, C18:1 ω7c/C18:1 ω6c and C16:1 ω7c/C16:1 ω6c. Phylogenetic analysis based on 16S rRNA gene sequence comparisons indicated that strain 18B16333T was most closely related to Kingella potus CCUG 49773T (97.3%, 16S rRNA gene sequence identity) and Neisseria bacilliformis CCUG 50858T (96.8%). The ANI values between strain 18B16333T and the type strains K. potus CCUG 49773T, N. bacilliformis CCUG 50858T, Kingella kingae CCUG 352T and Neisseria gonorrhoeae CCUG 26876T were 77.3%, 79.1%, 72.1% and 75.4%, respectively. The dDDH values between strain 18B16333T and the four reference strains mentioned above were 24.8%, 26.9%, 24.2% and 20.7%. Further core gene analysis distinctively clustered strain 18B16333T with four Kingella species but not with Neisseria species. Based on the phenotypic, chemotaxonomic, and phylogenetic properties, strain 18B16333T represents a novel species of the genus Kingella, for which the name Kingella pumchi sp. nov. is proposed. The type strain is Kingella pumchi 18B16333T (= CICC 24913T = CCUG 75125T).

Isolation and Characterization of Kingella bonacorsii sp. nov., A Novel Kingella Species Detected in a Stable Periodontitis Subject.

Members of the genus Kingella are mostly commensals of the oral cavity, but some of them are involved in invasive infections, especially in young children. This study provides new knowledge on the diversity of this genus by describing a novel species of Kingella isolated from a dental plaque sample from a 51-year-old man with a history of periodontitis. Morphological and chemotaxonomic characteristic were investigated using different growth conditions, pH and temperature. Cellular fatty acid methyl ester (FAME) analysis was performed by gas chromatography/mass spectrometry (GC/MS). Phylogenetic analysis based on 16S rRNA, orthologous average nucleotide identity (OrthoANI) and digital DNA–DNA hybridization (dDDH) relatedness were also performed. Strain Marseille-Q4569T was found to be a facultative aerobic, nonmotile and non-spore-forming rod-shaped bacterium that grows at 28–41.5 °C (optimum 37 °C), pH 5.5–8.5 (optimum pH 7.5) and 5–15 g/L of NaCl. The major fatty acids were Hexadecanoic acid (32.7%), 11-Octadecenoic acid (26.1 %) and 9-Hexadecenoic acid (21.3 %). Despite high 16S rRNA gene sequence similarity (98.72%) between strain Marseille-Q4569T and Kingella oralis strain UB-38T, the degree of OrthoANI was at the limit of the cutoff (95.83%), and the degree of dDDH was lower (63.6%) than thresholds used to delineate prokaryotic species. Therefore, it is proposed that strain Marseille-Q4569T represents a novel species of the genus Kingella, for which the name Kingella bonacorsii sp. nov. is proposed (=CSUR Q4569).

Abdominal Positron Emission Tomography Combined With Magnetic Resonance Imaging in Chronic Granulomatous Disease

Abdominal Positron Emission Tomography Combined With Magnetic Resonance Imaging in Chronic Granulomatous Disease

Osteoarticular Infection in Three Young Thoroughbred Horses Caused by a Novel Gram Negative Cocco-Bacillus

We describe three cases of osteoarticular infection (OAI) in young thoroughbred horses in which the causative organism was identified by MALDI-TOF as Kingella species. The pattern of OAI resembled that reported with Kingella infection in humans. Analysis by 16S rRNA PCR enabled construction of a phylogenetic tree that placed the isolates closer to Simonsiella and Alysiella species, rather than Kingella species. Average nucleotide identity (ANI) comparison between the new isolate and Kingella kingae and Alysiella crassa however revealed low probability that the new isolate belonged to either of these species. This preliminary analysis suggests the organism isolated is a previously unrecognised species.

Respiratory carriage of the novel Kingella negevensis species by young children.

Kingella negevensis, a novel Kingella species implicated in a pediatric joint infection, has been recently characterized but its epidemiology remains largely unknown. The pharyngeal carriage of K. negevensis was studied by re-examining the results of a previous longitudinal study conducted in a cohort of healthy Israeli children from whom upper respiratory tract specimens were sequentially cultured between the ages of 2 and 36 months. Isolates were identified as K. negevensis by a species-specific nucleic amplification assay and genotyped by pulsed-field gel electrophoresis. β-lactamase production was determined by the nitrocephin test. Kingella negevensis was detected in 26 of 4,472 (0.58%) oropharyngeal cultures obtained from 24 of 716 children (3.35%) and was not isolated from any of 4,472 nasopharyngeal specimens. Following the first 6 months of life during which none of the children was colonized, the prevalence of carriage gradually increased reaching a peak of 1.09% at 24 months of age and decreased thereafter. Kingella negevensis strains showed genomic heterogeneity, and two clones represented 22 of 26 (84.62%) isolates. Twelve of the 26 (46.15%) isolates, belonging to two distinct clones, produced β-lactamase. Kingella negevensis shows remarkable similarities with K. kingae in terms of colonization site, age-related patterns of acquisition and carriage, and clonal distribution of β-lactamase production. Additional research is needed to investigate potential colonization sites of K. negevensis outside the respiratory tract, explore the mechanisms of pharyngeal colonization by the organism, and determine its role as an invasive human pathogen.

A modified multilocus sequence typing protocol to genotype Kingella kingae from oropharyngeal swabs without bacterial isolation

BackgroundOutbreaks of Kingella kingae infection are an emerging public health concern among daycare attendees carrying epidemic clones in the oropharynx. However, genotyping of such epidemic clones from affected cases is limited by the low performance of current methods to detect K. kingae from blood samples and lack of specimens available from infected sites. We aimed at developing a modified multilocus sequence typing (MLST) method to genotype K. kingae strains from oropharyngeal samples without prior culture. We designed in silico MLST primers specific for K. kingae by aligning whole nucleotide sequences of abcZ, adk, aroE, cpn60, recA, and gdh/zwf genes from closely related species belonging to the Kingella and Neisseria genera. We tested our modified MLST protocol on all Kingella species and N. meningitidis, as well as 11 oropharyngeal samples from young children with sporadic (n = 10) or epidemic (n = 1) K. kingae infection.ResultsWe detected K. kingae-specific amplicons in the 11 oropharyngeal samples, corresponding to sequence-type 6 (ST-6) in 6 children including the epidemic cases, ST-25 in 2 children, and 3 possible novel STs (ST-67, ST-68, and ST-69). No amplicon was obtained from other Kingella species and N. meningitidis.ConclusionsWe herein developed a specific MLST protocol that enables genotyping of K. kingae by MLST directly from oropharyngeal samples. This discriminatory tool, with which we identified the first K. kingae outbreak caused by ST-6 in Europe, may be used in further epidemiological investigations.

Isolation and characterization of Kingella negevensis sp. nov., a novel Kingella species detected in a healthy paediatric population.

We herein report the isolation and characterization of 21 Gram-stain-negative strains cultivated from the oropharynx of healthy children in Israel and Switzerland. Initially described as small colony variants of Kingella kingae, phenotypic analysis, biochemical analysis, phylogenetic analysis based on sequencing of the partial 16S rRNA gene and five housekeeping genes (abcZ, adk, G6PD, groEL and recA), and whole genome sequencing and comparison between members of the genera Kingella and Neisseria provided evidence for assigning them to the genus Kingella. Cellular fatty acids included important amounts of C12 : 0, C14 : 0, C16 : 0 and C16 : 1n7. Digital DNA-DNA hybridization between the isolates Sch538T and K. kingae ATCC 23330T revealed relatedness of 19.9 %. Comparative analysis of 16S rRNA gene sequences available in GenBank allowed matches to strains isolated in the USA, suggesting a wider geographical distribution. A novel species named Kingella negevensis sp. nov. is proposed, as most strains have been isolated in the Negev, a desert region of southern Israel. The type strain is Sch538T (=CCUG 69806T=CSUR P957).

Prognosis and outcome of exogenous bacterial osteomyelitis: A prospective cohort study

Background and Objectives: Exogenous osteomyelitis frequently follows traumatic or surgical inoculation of bacteria into bone and surrounding tissue. It is usually associated with open fractures, surgical implants, orthopaedic fixation devices and vascular insufficiencies such as diabetes mellitus, peripheral vascular diseases and presence of foreign bodies. The aim of this study was to identify the pathogenic bacteria causing osteomyelitis and to evaluate the prognosis and outcome of patients with exogenous osteomyelitis. Materials and Methods: Patients admitted with clinical and radiological features of exogenous osteomyelitis were selected for the study from June 2005 to October 2006. Bone curettings or aspirated materials from the sinus tract were collected. The specimens were cultured on appropriate media for bacterial culture. The patients who consented were followed up for 6 months to record their progress and outcome. Those followed up included both culture positives and negatives. Results: Out of 125 cases of osteomyelitis, 75 (60%) were positive by culture, 59 (78.7%) were monomicrobial infections and 16 (21.3%) were polymicrobial infections. Staphylococcus aureu s, 56 (60.8%) in number, was the predominant organism isolated followed by Escherichia coli, eight (8.7%); Klebsiella pneumoniae, seven (7%); Pseudomonas aeruginosa, five (5.4%); β-haemolytic streptococci, four (4.4%); Proteus mirabilis, three (3.2%); Enterococcus faecalis, two (2.2%); Acinetobacter baumannii, two (2.2%); Corynebacterium jeikeium, one (1.1%); Staphylococcus epidermidis, one (1.1%); Proteus vulgaris, one (1.1%); Kingella species one (1.1%) and Arcanobacterium species, one (1.1%). Out of the coagulase-positive staphylococci, 29 (51.8%) were Methicillin-resistant S. aureus. Of the 61 cases that were followed up, 44 cases were culture positive. The total cure rate was 60.2%. Conclusion: Appropriate antibiotic therapy after culture and sensitivity has a major role in treating exogenous osteomyelitis in the presence of fracture and instability of bone. In spite of appropriate surgical correction, the major risk factors that led to recurrence of infections and amputations were overcrowding in wards, extensive tissue injury, poor economic status of patients, non-availability of drugs in the hospital pharmacy, poor compliance of patients and drug toxicity.

Update on the HACEK Group of Fastidious Gram-Negative Bacilli, Part II

The HACEK group of bacteria—Haemophilus parainfluenzae, Aggregatibacter species (Aggregatibacter aphrophilus, Aggregatibacter actinomycetemcomitans, and Aggregatibacter segnis), Cardiobacterium species (Cardiobacterium hominis and Cardiobacterium valvarum), Eikenella corrodens, and Kingella species—are fastidious gram-negative bacilli that are found in the human upper respiratory and genitourinary tracts. The HACEK bacteria are particularly associated with bacteremia and endocarditis, along with a variety of other infectious processes. This article describes the taxonomic status of the HACEK group, the types of infections and clinical specimens that may yield such organisms on culture, the phenotypic characteristics that are useful for species identification, and the susceptibility of these organisms to antimicrobial agents used for the treatment of HACEK group infections. Part I of this article addressed the clinical significance of the HACEK group and specifically addressed Haemophilus, Aggregatibacter, and Cardiobacterium. In Part II of this article, Eikenella, Suttonella, and Kingella are discussed as will the susceptibility patterns for all of these organisms.

Update on the HACEK group of fastidious gram-negative bacilli, Part I

The HACEK group of bacteria—Haemophilus parainfluenzae, Aggregatibacter species (Aggregatibacter aphrophilus, Aggregatibacter actinomycetemcomitans, and Aggregatibacter segnis), Cardiobacterium species (Cardiobacterium hominis and Cardiobacterium valvarum), Eikenella corrodens, and Kingella species—are fastidious gram-negative bacilli that are found in the human upper respiratory and genitourinary tracts. The HACEK bacteria are particularly associated with bacteremia and endocarditis, along with a variety of other infectious processes. This article describes the taxonomic status of the HACEK group, the types of infections and clinical specimens that may yield such organisms on culture, the phenotypic characteristics that are useful for species identification, and the susceptibility of these organisms to antimicrobial agents used for the treatment of HACEK group infections. Part I of this article will addresses the clinical significance of the HACEK group and specifically addresses Haemophilus, Aggregatibacter, and Cardiobacterium.

HACEK Infective Endocarditis: Characteristics and Outcomes from a Large, Multi-National Cohort

The HACEK organisms (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are rare causes of infective endocarditis (IE). The objective of this study is to describe the clinical characteristics and outcomes of patients with HACEK endocarditis (HE) in a large multi-national cohort. Patients hospitalized with definite or possible infective endocarditis by the International Collaboration on Endocarditis Prospective Cohort Study in 64 hospitals from 28 countries were included and characteristics of HE patients compared with IE due to other pathogens. Of 5591 patients enrolled, 77 (1.4%) had HE. HE was associated with a younger age (47 vs. 61 years; p<0.001), a higher prevalence of immunologic/vascular manifestations (32% vs. 20%; p<0.008) and stroke (25% vs. 17% p = 0.05) but a lower prevalence of congestive heart failure (15% vs. 30%; p = 0.004), death in-hospital (4% vs. 18%; p = 0.001) or after 1 year follow-up (6% vs. 20%; p = 0.01) than IE due to other pathogens (n = 5514). On multivariable analysis, stroke was associated with mitral valve vegetations (OR 3.60; CI 1.34–9.65; p<0.01) and younger age (OR 0.62; CI 0.49–0.90; p<0.01). The overall outcome of HE was excellent with the in-hospital mortality (4%) significantly better than for non-HE (18%; p<0.001). Prosthetic valve endocarditis was more common in HE (35%) than non-HE (24%). The outcome of prosthetic valve and native valve HE was excellent whether treated medically or with surgery. Current treatment is very successful for the management of both native valve prosthetic valve HE but further studies are needed to determine why HE has a predilection for younger people and to cause stroke. The small number of patients and observational design limit inferences on treatment strategies. Self selection of study sites limits epidemiological inferences.

&lt;i&gt;Kingella Kingae&lt;/i&gt; a Potentially Emerging Pathogen: A Comprehensive Review

Kingella kingae are a group of fastidious Gram negative bacilli that were first described way back in 1960's as CDC group M-1. Initially placed in moraxella family, Kingella spp have later been classified separately under Neisseriaceae family. Kingella kingae is the most common species responsible for human infections and is characterized along with other fastidious bacteria named as HACEK group. Kingella kingae , K. denitrificans , K indologenes and K oralis are few species of Kingella . Kingella kingae has gradually evolved from a bacterium that normally colonizes oral cavity, upper respiratory tract and genital tract in to a potential pathogen in children and debilitated patients. Recent trends of Kingella kingae infections among adult population should be considered as an alarming signal. The spectrum of infections, indifferent cultural and biochemical characters, antimicrobial susceptibility pattern, complex pathogenicity and genetic polymorphism has attracted a lot of interested among paediatricians, orthopedicians and clinical microbiologists.

&lt;i&gt;Kingella kingae&lt;/i&gt; による右踵骨骨髄炎の 1 症例

Kingella species including K. kingae are non-motile coccobacilli or short straight rods, and their normal habitats appear to be the upper respiratory and oropharyngeal tracts of humans. In recent years, K. kingae strains have been increasingly recognized as common causes of invasive infections in children at the age of less than 4 years. In Japan, however, invasive K. kingae infections including osteomyelitis have rarely been described. We incidentally encountered isolation of a K. kingae strain from intraoperatively obtained specimens from a previously healthy 44-month-old boy. He first consulted a nearby medical facility and a suspected diagnosis of osteomyelitis was made, after which the patient was then transferred to our Nagano Children's hospital. There was evidence of inflammation in his right calcaneus and toe walking was noted. He was treated with surgical drainage. An isolate grown on sheep blood agar with positive oxidase and negative catalase was biochemically characterized with the ID-Test HN20 (Nissui Pharmaceutical Co., Ltd., Tokyo, Japan) kit system together with genetic examinations involving sequencing the 16S rRNA gene, and the infection was finally identified as K. kingae. The patient was successfully treated with cefotiam (CTM) for the first 7 days followed by the administration of trimethoprim-sulfamethoxazole (ST) for an additional 2 months. The K. kingae isolate was confirmed as a sure causative pathogen by observing that the serum showed high agglutinin titers against the isolate. Accumulation of the case reports in Japan with the isolation of this species is essential for clarifying invasive infections due to K. kingae. Our case report is a noteworthy and useful piece of information.

Microbial community succession on developing lesions on human enamel

BackgroundDental caries is one of the most common diseases in the world. However, our understanding of how the microbial community composition changes in vivo as caries develops is lacking.ObjectiveAn in vivo model was used in a longitudinal cohort study to investigate shifts in the microbial community composition associated with the development of enamel caries.DesignWhite spot lesions were generated in vivo on human teeth predetermined to be extracted for orthodontic reasons. The bacterial microbiota on sound enamel and on developing carious lesions were identified using the Human Oral Microbe Identification Microarray (HOMIM), which permits the detection of about 300 of the approximate 600 predominant bacterial species in the oral cavity.ResultsAfter only seven weeks, 75% of targeted teeth developed white spot lesions (8 individuals, 16 teeth). The microbial community composition of the plaque over white spot lesions differed significantly as compared to sound enamel. Twenty-five bacterial taxa, including Streptococcusmutans, Atopobiumparvulum, Dialisterinvisus, and species of Prevotella and Scardovia, were significantly associated with initial enamel lesions. In contrast, 14 bacterial taxa, including species of Fusobacterium, Campylobacter, Kingella, and Capnocytophaga, were significantly associated with sound enamel.ConclusionsThe bacterial community composition associated with the progression of enamel lesions is specific and much more complex than previously believed. This investigation represents one of the first longitudinally-derived studies for caries progression and supports microbial data from previous cross-sectional studies on the development of the disease. Thus, the in vivo experiments of generating lesions on teeth destined for extraction in conjunction with HOMIM analyses represent a valid model to study succession of supragingival microbial communities associated with caries development and to study efficacy of prophylactic and restorative treatments.

Pseudomonas aeruginosa PilY1 Binds Integrin in an RGD- and Calcium-Dependent Manner

PilY1 is a type IV pilus (tfp)-associated protein from the opportunistic pathogen Pseudomonas aeruginosa that shares functional similarity with related proteins in infectious Neisseria and Kingella species. Previous data have shown that PilY1 acts as a calcium-dependent pilus biogenesis factor necessary for twitching motility with a specific calcium binding site located at amino acids 850–859 in the 1,163 residue protein. In addition to motility, PilY1 is also thought to play an important role in the adhesion of P. aeruginosa tfp to host epithelial cells. Here, we show that PilY1 contains an integrin binding arginine-glycine-aspartic acid (RGD) motif located at residues 619–621 in the PilY1 from the PAK strain of P. aeruginosa; this motif is conserved in the PilY1s from the other P. aeruginosa strains of known sequence. We demonstrate that purified PilY1 binds integrin in vitro in an RGD-dependent manner. Furthermore, we identify a second calcium binding site (amino acids 600–608) located ten residues upstream of the RGD. Eliminating calcium binding from this site using a D608A mutation abolished integrin binding; in contrast, a calcium binding mimic (D608K) preserved integrin binding. Finally, we show that the previously established PilY1 calcium binding site at 851–859 also impacts the protein's association with integrin. Taken together, these data indicate that PilY1 binds to integrin in an RGD- and calcium-dependent manner in vitro. As such, P. aeruginosa may employ these interactions to mediate host epithelial cell binding in vivo.

Retropharyngeal Abscess from an Unusual Organism—Kingella Denitrificans—in a Patient on Low-Dose Methotrexate

Retropharyngeal abscess can be a life-threatening emergency with potential for airway compromise. We report a case of retropharyngeal abscess caused by Kingella denitrificans in a 66-year-old Caucasian man taking low-dose methotrexate for psoriatic arthritis. K denitrificans has not been previously reported as a cause of retropharyngeal abscess. K denitrificans, along with other Kingella species, is often found to be part of the normal upper respiratory tract flora. Potentially life-threatening complications of retropharyngeal abscess can occur in immunocompromised patients. Although complications of immunosuppression are thought to be rare with the use of low-dose pulse methotrexate for non-neoplastic conditions, such complications with prolonged use of low-dose pulse methotrexate may be seen.

Gram-negative bacterial endocarditis in adults: state-of-the-heart

Gram-negative endocarditis due to HACEK bacteria (Haemophilus species, Actinobacillus, Cardiobacterium, Eikenella and Kingella species) and non-HACEK organisms is an infrequent occurrence but is associated with significant morbidity and mortality. Traditionally, non-HACEK Gram-negative endocarditis has been associated with injection drug use. However, emerging data from more contemporary cohorts suggest changing epidemiology and risk factors for Gram-negative endocarditis, necessitating an updated review of this subject. Moreover, optimal management, including the need for surgical intervention, and strategies for the prevention of Gram-negative endocarditis need to be revisited.

Cardiobacterium hominis endocarditis: two cases and a review of the literature

Cardiobacterium hominis, a member of the HACEK group (Haemophilus parainfluenzae, Haemophilus aphrophilus, and Haemophilus paraphrophilus, Actinobacillus actinomycetemcomitans, C. hominis, Eikenella corrodens, and Kingella species), is a rare cause of endocarditis. There are 61 reported cases of C. hominis infective endocarditis in the English-language literature, 15 of which involved prosthetic valve endocarditis. There is one reported case of C. hominis after upper endoscopy and none reported after colonoscopy. Presented here are two cases of C. hominis prosthetic valve endocarditis following colonoscopy and a review of the microbiological and clinical features of C. hominis endocarditis. Patients with C. hominis infection have a long duration of symptoms preceding diagnosis (138+/-128 days). The most common symptoms were fever (74%), fatigue/malaise (53%), weight loss/anorexia (40%), night sweats (24%), and arthralgia/myalgia (21%). The most common risk factors were pre-existing cardiac disease (61%), the presence of a prosthetic valve (28%), and history of rheumatic fever (20%). Of the 61 cases reviewed here, the aortic valve was infected in 24 (39%) and the mitral valve in 19 (31%) patients. The average duration of blood culture incubation before growth was detected was 6.3 days (range, 2-21 days). Complications were congestive heart failure (40%), central nervous system (CNS) emboli (21%), arrhythmia (16%), and mycotic aneurysm (9%). C. hominis is almost always susceptible to beta-lactam antibiotics. Ceftriaxone is recommended by the recently published American Heart Association guidelines. The prognosis of C. hominis native valve and prosthetic valve endocarditis is favorable. The cure rate among 60 patients reviewed was 93% (56/60). For prosthetic valve endocarditis, the cure rate was 16/17 (94%). Valve replacement was required in 27 (45%) cases.