F.P. Pimenta

Potential pathogenic role of aggregative-adhering Corynebacterium diphtheriae of different clonal groups in endocarditis.

Invasive diseases caused by Corynebacterium diphtheriae have been described increasingly. Several reports indicate the destructive feature of endocarditis attributable to nontoxigenic strains. However, few reports have dealt with the pathogenicity of invasive strains. The present investigation demonstrates a phenotypic trait that may be used to identify potentially invasive strains. The study also draws attention to clinical and microbiological aspects observed in 5 cases of endocarditis due to C. diphtheriae that occurred outside Europe. Four cases occurred in female school-age children (7-14 years) treated at different hospitals in Rio de Janeiro, Brazil. All patients developed other complications including septicemia, renal failure and/or arthritis. Surgical treatment was performed on 2 patients for valve replacement. Lethality was observed in 40% of the cases. Microorganisms isolated from 5 blood samples and identified as C. diphtheriae subsp mitis (N = 4) and C. diphtheriae subsp gravis (N = 1) displayed an aggregative adherence pattern to HEp-2 cells and identical one-dimensional SDS-PAGE protein profiles. Aggregative-adhering invasive strains of C. diphtheriae showed 5 distinct RAPD profiles. Despite the clonal diversity, all 5 C. diphtheriae invasive isolates seemed to display special bacterial adhesive properties that may favor blood-barrier disruption and systemic dissemination of bacteria. In conclusion, blood isolates from patients with endocarditis exhibited a unique adhering pattern, suggesting a pathogenic role of aggregative-adhering C. diphtheriae of different clones in endocarditis. Accordingly, the aggregative-adherence pattern may be used as an indication of some invasive potential of C. diphtheriae strains.

First detection of Corynebacterium ulcerans producing a diphtheria-like toxin in a case of human with pulmonary infection in the Rio de Janeiro metropolitan area, Brazil

The frequency and severity of human infections associated with Corynebacterium ulcerans appear to be increasing in different countries. Here, we describe the first C. ulcerans strain producing a diphtheria-like toxin isolated from an elderly woman with a fatal pulmonary infection and a history of leg skin ulcers in the Rio de Janeiro metropolitan area.

Periodontal disease as reservoir for multi‐resistant and hydrolytic enterobacterial species

Aims:  This investigation aimed to isolate enteric rods from subgingival sites of patients presenting chronic periodontitis lesions, and to assess antimicrobial resistance and expression of hydrolytic enzymes.

A multiplex PCR assay for simultaneous detection of Corynebacterium diphtheriae and differentiation between non-toxigenic and toxigenic isolates

The importance of identifying Corynebacterium diphtheriae can be appreciated since diphtheria remains endemic in many countries, alongside the risk of epidemic outbreaks and the existence of a large number of non-immunized people worldwide (Galazka & Robertson, 1995; Damasco et al., 2005). The features of infections caused by C. diphtheriae have changed over the decades, and are most clearly emphasized by the emergence of non-toxigenic strains causing atypical diseases, such as endocarditis, septic arthritis or infection in unusual anatomical sites (Mattos-Guaraldi & Formiga, 1998; Efstratiou & George, 1999; Reacher et al., 2000; Mattos-Guaraldi et al., 2003). Rapid and reliable methods are needed for identifying a C. diphtheriae infection, thus aiding in appropriate and timely patient management, and improved monitoring of cases.

Corynebacterium pseudodiphtheriticum isolated from relevant clinical sites of infection: a human pathogen overlooked in emerging countries

Aims:  To examine the occurrence of and to determine the antimicrobial susceptibility of Corynebacterium pseudodiphtheriticum among patients with bacterial infections at a teaching hospital.

A PCR for dtxR gene: application to diagnosis of non-toxigenic and toxigenic Corynebacterium diphtheriae.

The significant rise in the percentage of adults susceptible to diphtheria and the emergence of non-toxigenic Corynebacterium diphtheriae strains as the causative agent of endocarditis and other systemic infections emphasize the need for alternative laboratory diagnostic procedures. In this study, for the first time, the value of a species-specific PCR assay that targets the dtxR gene is documented as a procedure for differentiating C. diphtheriae from Corynebacterium-like colonies. The results of the PCR-dtxR were all positive for 91 C. diphtheriae (54 non-toxigenic and 37 toxigenic) strains. PCR-dtxR completely correlated with the standard biochemical and commercial identification for all C. diphtheriae strains tested. Conversely, the PCR-dtxR results were negative in 100% of the 111 non-diphtherial Gram-positive rod strains obtained during identification procedures in a hospital laboratory. Thus, the PCR-dtxR assay emerged as viable, cost-effective screening method for C. diphtheriae laboratory identification.

Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 microg/ml) to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 microg/ml) and azithromycin (MIC90 0.064 microg/ml) were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 microg/ml) to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74%) showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

DNase test as a novel approach for the routine screening of Corynebacterium diphtheriae

Aims:  To examine the value of the DNase test as an alternative procedure for differentiating Corynebacterium diphtheriae from Corynebacterium‐like colonies.

DIPHTHERIA IN A VACCINATED ADULT IN RIO DE JANEIRO, BRAZIL

Um caso de difteria ocorreu, em 1999, em mulher de 32 anos de idade. A paciente iniciou episodio de dor de garganta imediatamente apos participacao em reuniao com profissionais europeus durante cinco dias consecutivos, no Rio de Janeiro. Ela declarou ter sido submetida ao esquema completo de imunizacao contra difteria (DTP-triplice bacteriana) na infância e a doses de reforco (dT-dupla adulto) ha dois anos. O diagnostico clinico da doenca so foi firmado apos o laboratorio de microbiologia ter confirmado a capacidade de producao de toxina pela amostra isolada de Corynebacterium diphtheriae var. gravis, biotipo nao fermentador de sacarose comumente encontrado em diversos paises europeus e responsavel pela atual epidemia na regiao correspondente a antiga Uniao Sovietica. Na era da vacinacao antidifterica, individuos adultos de nossa comunidade podem apresentar-se potencialmente susceptiveis a difteria.

Prevalence of IgG diphtheria antitoxin in blood donors in Rio de Janeiro

The lack of information on the immunity of adults in Brazil against diphtheria prompted us to analyse sera from 234 blood donors aged 18-61 years (30.3% females and 69.7% males). IgG diphtheria antitoxin levels determined by means of an ELISA, validated by toxin neutralization test in Vero cells, showed that 30.7% (95% CI 25.0-37.1) of the population was fully protected (>or=1 IU/ml). The highest percentage of subjects fully protected was in the 31-40 years age group. Most of the subjects with uncertain or no protection (<1 IU/ml) were found in the 18-30 years age group (43.8%, OR 2.18, P=0.01). Antitoxin levels were not influenced by the increase in age. Males were more protected than females (80.5%, OR 0.44, P=0.01). The prevalence of 30% of individuals fully protected against diphtheria in blood donors in Rio de Janeiro supports the fact that immunity to diphtheria among healthy Brazilian adults is inadequate. To avoid diphtheria epidemics in the future the immunity among adults should be raised in the coming years.