Luiz Carlos Duarte Formiga

Cell surface components and adhesionin Corynebacterium diphtheriae

Main primary approaches and new developments in the study of the molecular basis of the adhesive process of Corynebacterium diphtheriae are reviewed along with a discussion of the potential importance of hemagglutinins, exposed sugar residues, hydrophobins and trans-sialidase enzymes as adhesins of strains of the sucrose fermenting and non-fermenting biotypes.

Cell Surface Hydrophobicity of Sucrose Fermenting and Nonfermenting Corynebacterium diphtheriae Strains Evaluated by Different Methods

Abstract.Corynebacterium diphtheriae strains expressed variation in hydrophobic characteristics dependent on the method used. Results of single assays are not a reliable representation of C. diphtheriae hydrophobicity. All 12 strains adhered to polystyrene surfaces; three showed spontaneous aggregation (SA) in Trypticase Soy Broth (TSB) medium, and eight exhibited autoagglutination in phosphate-buffered saline (PBS; AA-positive). The salt aggregation test (SAT) values ≤0.002 or ≥1.6 represented breakpoints for groups of strains with differing hydrophobicity. C. diphtheriae strains showed affinity towards n-hexadecane. Percentages of adhesion varied from 31% to 63% and were not directly related to morphological n-hexadecane adhesion patterns. Diffuse and localized adhesion patterns were noted predominantly among sucrose-positive and sucrose-negative strains, respectively. Strains of the sucrose-negative biotype expressed a higher degree of hydrophobicity. The choice of the growth medium influenced the hydrophobicity, not the hemagglutinating activity (HA) of C. diphtheriae. Heating bacterial suspensions at 121°C decreased both HA and hydrophobicity of three strains. However, hydrophobins and hemagglutinins were trypsin and detergent resistant. The treatment of microorganisms with Clostridium perfringens neuraminidase increased the hydrophobicity but not the HA titers of strains tested. Hemagglutinins were partially responsible for hydrophobicity. Hydrophilic AA-negative strains adhered strongly to glass but expressed weak HA. Sialylglycoconjugates functioned as hydrophilins on C. diphtheriae surfaces.

Nondiphtherial Corynebacterium species isolated from clinical specimens of patients in a university hospital, Rio de Janeiro, Brazil

Over a five-year period, 163 strains of Corynebacterium sp. were recovered from different clinical specimens of patients from a Brazilian University hospital. Genitourinary tract and intravenous sites specimens were the most frequent sources of corynebacteria (46.62%). Corynebacterium amycolatum (29.55%), Corynebacterium minutissimum (20.45%) and Corynebacterium pseudodiphtheriticum (13.63%) were the predominant species found in genitourinary tract. C. minutissimum (24.14%) and Corynebacterium propinquum (17.24%) in surgical and/or other skin wounds and abscesses; Corynebacterium xerosis (25%), C. amycolatum (21.87%) and C. pseudodiphtheriticum (18.75%) in intravenous sites; C. pseudodiphtheriticum (33.33%) and C. propinquum (33.33%) in lower respiratory tract. Microorganisms were all susceptible to vancomycin and most of the species was predominantly resistant to b-lactams. Antimicrobial susceptibility patterns of corynebacteria were not predictable. Multiple antibiotic resistance observed in C. jeikeium was also found among C. xerosis, C. minutissimum, C. afermentans, C. propinquum, C. amycolatum and C. pseudodiphtheriticum strains. Data suggest awareness of clinicians and microbiologists to nosocomial infections especially due to antimicrobial multiresistant strains of Corynebacterium sp.

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.