Corynebacterium pseudodiphtheriticum--a skin pathogen

Complete Genome Sequences of Four Macrolide-Resistant Nondiphtheritic Corynebacterium Isolates

This report describes the complete genome sequences of four isolates of the nondiphtheritic Corynebacterium (NDC) species Corynebacterium pseudodiphtheriticum and Corynebacterium propinquum, recovered during investigation of a large diphtheria outbreak in Bangladesh. These data will assist in better delineating the boundary between these related species and understanding their virulence potential.

Exudative pharyngitis and Corynebacterium pseudodiphtheriticum: A case report and review of the literature

Corynebacterium pseudodiphtheriticum is an established member of the normal flora of the respiratory tract. This organism is an emerging cause of respiratory tract infection, as well as infection of the skin and skin structures, urinary tract and other sterile sites. The syndrome of C. pseudodiphtheriticum exudative pharyngitis is a diagnostic challenge of particular relevance in recent times as this organism can be confused with Corynebacterium diphtheriae in the clinical setting and in the laboratory. We report a case of exudative pharyngitis, possibly due to C. pseudodiphtheriticum, in a 14-month old, incompletely vaccinated, human immunodeficiency virus (HIV)-positive infant and review the role of this organism in terms of its microbiological profile and identification, disease spectrum and antimicrobial susceptibility pattern.

Infection and colonization by Corynebacterium pseudodiphtheriticum: a 9-year observational study in a university central hospital

Despite constituting part of the human commensal flora, Corynebacterium pseudodiphtheriticum has been recognized as a potentially infectious agent, most frequently in immunocompromised patients or individuals with other morbidity factors, but significant association to comorbid states remains unproven. This study's purpose was to assess clinical significance, risk factors for infection and antimicrobial susceptibility of C. pseudodiphtheriticum isolates. A retrospective observational study was conducted. Relevance of isolation was determined by clinical, laboratory, and imaging criteria. Forty-nine isolates occurred in 47 episodes. Colonization was assumed in 12% and infection in 78%, of which 51% were nosocomial. Patients with infection were older, with male predominance; both age and gender were statistically significant (p < 0.05) between infection and colonization groups. Although dyslipidemia (58%), arterial hypertension (58%), invasive procedures (56%), and chronic lung disease (50%) were prevalent in the infection group, no comorbidity was a significant risk factor for infection compared with colonization. Charlson comorbidity index showed no statistically difference between groups. Mortality rate was 14% in infection. Respiratory samples were the main isolation product; all tested strains were susceptible to amoxicillin/clavulanate and vancomycin. Resistant strains were observed for clindamycin (77%) and erythromycin (48%). C. pseudodiphtheriticum isolation was associated with infection in most cases. Despite the high prevalence of comorbidities and invasive procedures, no factors other than age and gender were significantly associated with infection. Although C. pseudodiphtheriticum may constitute a contaminant or colonizer in clinical samples, positive cultures in patients with signs and symptoms consistent with infection should not be neglected.

Microbiological investigation and clinical significance of Corynebacterium spp. in respiratory specimens

The purpose of this retrospective study was to evaluate the pathogenic role of Corynebacterium species in lower respiratory tract infections as well as their routine laboratory investigation. From April 2007 to August 2009, 27 clinical isolates were significantly recovered from respiratory specimens of 27 different patients clinically suspected of having lower respiratory tract infections. The average age of patients was 65 years, while 22 (81%) patients presented at least 1 predisposing condition. Of the 27 patients, 15 (56%) were classified as infected according to Centers for Disease Control and Prevention/National Healthcare Safety Network criteria, with 93% of infections being hospital acquired. All isolates were accurately identified to the species level using molecular methods (i.e., 17 Corynebacterium pseudodiphtheriticum, 7 Corynebacterium striatum, and 3 Corynebacterium accolens), whereas phenotypic methods remained frequently unreliable for identifying C. striatum and C. accolens strains. All tested isolates were susceptible to amoxicillin, imipenem, vancomycin, linezolid, and tigecycline, whereas most of them were resistant to erythromycin.

Macrolide, lincosamide, and streptogramin B-constitutive-type resistance in Corynebacterium pseudodiphtheriticum isolated from upper respiratory tract specimens

Corynebacterium pseudodiphtheriticum is commonly found in normal upper respiratory tract flora in humans. In certain conditions it can cause the opportunistic infections, especially in immunocompromised patients. In certain strains of Corynebacterium sp., the macrolide, lincosamide, and streptogramin B (MLSb) resistance mechanism related to the presence of the erm(X) gene was discovered; hence, the need appeared for further investigation to confirm the existence of this gene among C. pseudodiphtheriticum. About 58 strains of C. pseudodiphtheriticum were used in this study. All strains were isolated from the nasal mucous membrane of patients with upper respiratory tract infection symptoms. Among the tested strains 52 were erythromycin resistant, and only 6 were erythromycin sensitive. The tested strains showed a very high percentage (89.7%) of the phenotype MLSb-constitutive resistance mechanism. The MLSb-inducible resistance among the tested strains was not observed. Association of the MLSb mechanism with resistance to chloramphenicol, trimethoprim/sulfamethoxazole and chloramphenicol, and trimethoprim/sulfamethoxazole was observed in 12.1%, 15.5%, and 44.8% tested strains, respectively. Among all isolates with the phenotype MLSb resistance, the presence of the erm(X) gene was confirmed by the polymerase chain reaction method. The results suggest that C. pseudodiphtheriticum with the MLSb-constitutive-type resistance can play a significant role in crossing this mechanism with other Corynebacterium sp., which colonize the nasal and throat mucous membrane.

Cutaneous infection caused by Corynebacterium pseudodiphtheriticum: a microbiological report

We report here a rare case of cutaneous infection due to Corynebacterium pseudodiphtheriticum. The patient presented to the clinical laboratory with a skin ulcer on his left leg. Gram-stained preparation of the purulent secretion revealed the presence of numerous rod-shaped Gram-positive organisms in the absence of any other species. The organism was grown in pure culture on sheep blood agar and was further identified as C. pseudodiphtheriticum using a commercial identification system (API-Coryne, BioMérieux, France). The infection was successfully treated with ciprofloxacin. This case emphasizes the importance of the clinical microbiology laboratory in correctly identifying Gram-positive organisms obtained in pure culture from skin ulcers.

Infections caused by coryneform bacteria in pediatric oncology patients

BACKGROUND

Invasive infections caused by coryneform bacteria are uncommon but have been reported with increasing frequency in recent decades, especially in immunocompromised persons. Because pediatric experience is limited, we examined the epidemiology and clinical characteristics of these infections in children undergoing cancer therapy.

METHODS

Using strict case definitions, 17 coryneform bacterial infections were identified in 16 children during a 13-year period; there were 12 episodes of bacteremia and 5 skin or soft tissue infections.

RESULTS

The median age of children with bloodstream infections was 11.2 years, and that of children with skin or soft tissue infections was 3.5 years. Most were receiving cancer therapy at the time of their infections, were outpatients at the onset of their infections, had central venous catheters, and were not neutropenic. No patient died as a result of infection and most had relatively mild signs and symptoms. All patients responded promptly to antimicrobial therapy and, although 3 infections relapsed, there was only 1 serious complication. The most common species isolated were Corynebacterium striatum, C. amycolatum, and Microbacterium species.

CONCLUSIONS

The epidemiologic and clinical features of coryneform bacterial infections in immunocompromised children differ in several important respects from the previously reported characteristics of these infections in adults.