MALDI-TOF mass spectrometry proteomic based identification of clinical bacterial isolates.

Background & objectives: Pathogenic bacteria often cause life threatening infections especially in immunocompromised individuals. Therefore, rapid and reliable species identification is essential for a successful treatment and disease management. We evaluated a rapid, proteomic based technique for identification of clinical bacterial isolates by protein profiling using matrix-assisted laser desorption-ionization time - of - flight mass spectrometry (MALDI-TOF MS). Methods: Freshly grown bacterial isolates were selected from culture plates. Ethanol/formic acid extraction procedure was carried out, followed by charging of MALDI target plate with the extract and overlaying with α-cyano-4 hydroxy-cinnamic acid matrix solution. Identification was performed using the MALDI BioTyper 1.1, software for microbial identification (Bruker Daltonik GmbH, Bremen, Germany). Results: A comparative analysis of 82 clinical bacterial isolates using MALDI -TOF MS and conventional techniques was carried out. Amongst the clinical isolates, the accuracy at the species level for clinical isolates was 98.78%. One out of 82 isolates was not in accordance with the conventional assays because MALDI-TOF MS established it as Streptococcus pneumoniae and conventional methods as Streptococcus viridans. Interpretation & conclusions: MALDI - TOF MS was found to be an accurate, rapid, cost-effective and robust system for identification of clinical bacterial isolates. This innovative approach holds promise for earlier therapeutic intervention leading to better patient care.

Deficiencia congénita de complemento: C3 y C4: Comunicación de un caso clínico / Congenital deficiency of the C3 and C4 fractions of complement: a clinical report

Congenital deficiency of C3 fraction of the complement is a very rare condition. Clinically it is expressed as a deficiency of the humoral immunity. We report a case of C3 and C4 deficiency in a 1 year old infant girl. Her parents have a high consanguinity. She presented an acute meningoencephalitis of unknown etiology, and she evolved with severe neurological damage, and recurrent respiratory and urinary bacterial infections, sepsis and osteomielitis, with partial response to antimicrobials. The tests to investigate humoral and cellular immune response (lymphocyte subpopulations, serum immunoglobulins and subtypes of IgG) were normal. The patient had a deficit of C3 and C4, mainly C3, with absence of CH50. Both of her parents had C3 and C4 about 50 percent of normal values, and CH50 slightly under the normal values

La deficiencia congénita del 3er constituyente del Complemento (C3) es extremadamente rara, y se expresa clínicamente como un defecto de la inmunidad humoral. Se comunica un caso de deficiencia C3 y C4 en un lactante de sexo femenino de 1 año de edad, hijo de padres consanguíneos, que presentó un cuadro de meningoencefalitis aguda de etiología no precisada, con secuela neurológica severa e infecciones bacterianas recurrentes, respiratorias y urinarias, septicemia y osteomielitis, con respuesta parcial a antimicrobianos. El estudio de inmunidad humoral y celular (subpoblaciones linfocitarias, inmunoglobulinas séricas y subclases de IgG) fue normal, demostrándose déficit de C3 y C4 con CH50 ausente en la niña y cifras bajas de C3 y C4, cercanas al 50 por ciento del valor normal en ambos padres

Immunogenetics and infectious diseases: special reference to the mayor histocompatibility complex

Many studies have tried to identify genetic markers for infectious diseases, some of them have focused on human leukocyte antigens (HLA). The products of HLA genes interact with surface-specific receptors of T lymphocytes, resulting in activation of the host's immune response. Association of bacterial, viral, parasitic and fungal infections with the host's HLA has been widely investigated. The type and strength of this association differs among distinct populations, as well as among racial and/or ethnic groups. The new molecular methods for the identification of the HLA alleles, and the resulting new nomenclature, have contributed to a better understanding of this system. Unfortunately, this information has not been adequately transmitted to clinicians, which hampers the understanding of the association between the HLA system and diseases. We revised relevant studies on the association of HLA genes with infectious diseases, demonstrating their importance in the pathogenic mechanisms, through increased susceptibility or protection against infections and their complications.

Genes de virulência agr-dependentes em cepas de Staphylococcus aureus resistentes a oxacilina SCCmec tipo IV isoladas no Brasil / Agr-dependent virulence genes in SCCmec IV Oxacillin Resistant Staphylococcus aureus (ORSA) strains isolated in Brasil

O Staphylococcus aureus é um patógeno extremamente versátil tanto em termos de resistência a antimicrobianos quanto em virulência. O S.aureus resistente a oxacilina (ORSA) adquire a resistência a toda a classe de beta-lactâmicos através de um cassete cromossômico (SCCmec) que carrega o gene mecA, mas pode carregar outros genes de resistência. A soma desses genes de resistência e de virulência torna o S. aureus um grave problema para hospitais do mundo inteiro, que nos últimos vem se estendendo também à comunidade. Foram estudados 50 isolados de ORSA, dentre os quais 15 pertencentes ao clone endêmico brasileiro (CEB) e 3 cepas SCCmec tipo IV isoladas entre 1995 e 1999. Adicionalmente, 32 amstras ORSA SCCmec tipo IV isoladas no Hospital de Clínicas de São PAulo...

Staphylococcus aureus is an extremely successful pathogen for it is both highly resistant to antibiotics in addition to being virulent. Methicillin-resistant Staphylococcus aureus (MRSA) acquires resistance to the beta-Iactam antibiotics through the acquisition of a chromosomal cassette (SCCmec) which carries the mecA gene, and can carry other resistance genes. The presence of these genes in S. aureus makes it a serious problem in hospitaIs worldwide. In spite of usually being restricted to the nosocomial environment, over the last few years MRSA has been spreading throughout the community. Fifty nosocomial MRSA strains were studied, including 15 belonging to the Brazilian endemic clone (BEC), 3 type IV SCCmec strains isolated between 1995-1999, and 32 type N SCCmec isolates from the "Hospital de Clínicas (HC) de São Paulo". The isolates were analyzed as to their susceptibility profile, SCCmec type, virulence and expression profile (toxins and adhesins), agr group classification and functionality, PFGE and MLST profiles. BEC isolates proved to be multiresistant to antibiotics. Type IV SCCmec strains presented a susceptibility profile to a number of drugs of different antimicrobial classes. BEC and type N SCCmec strains did not present significant differences in their virulence profiles. Only the type IV SCCmec strains isolated in 1995-1999 presented a greater virulence profile than those isolated in the HC. Type IV SCCmec strains isolated in Brazil were not highly virulent as described in other countries. Brazilian isolates usually do not possess virulence factors such as the Panton-Valentine leukocidin, exfoliative toxins and enterotoxins. On the other hand, they usually possess alpha-hemolysin and the LukED leukocidin, which is still very poorly studied that have been presented in papers like cause of serious ocular lesions and post-antimicrobial therapy diarrhea. A relation between the agr type and the virulence profile was not established, for virulence profiles were very similar even between isolates belonging to different agr groups.

Doença granulomatosa crônica da infância: novos polimorfismos no gene NCF2 / Chronic granulomatous disease of childhood: new polymorphisms in NCF2 gene

Objetivos: Mutações no gene NCF2 resultam na forma autossônica recessiva da doença granulomatosa crônica da infância. Além de mutações conhecidas, descreveu-se em pacientes com doença granulomatosa crônica da infância duas novas substituições no gene NCF2. O objetivo deste estudo foi investigar se estas substituições constituem polimorfismos do gene NCF2. Métodos: Investigamos a freqüência de duas substituições na seqüência do gene NCF2 em 214 doadores sadios. A primeira é uma transição de C T na posição -23 da região 5' reguladora. A segunda é uma transição de A G na posição -21 da região 3' terminal do íntron 10. Extraímos DNA genômico de células do sangue periférico. O DNA foi amplificado por meio de PCR com primers específicos para o gene NCF2, analisado quanto à presença de polimorfismos conformacionais de cadeias simples, digerido com endonucleases específicas e sequenciado. O cálculo das freqüências genotípicas e alélicas seguiu a lei de Hardy e Weinberg. Resultados: Cem indivíduos foram avaliados quanto à presença da transição C T na posição -23 da região 5' reguladora; sendo 67 porcento homozigotos para o alelo c, 32 porcento heterozigotos, e apenas 1 porcento homozigoto para T. Cento e quatorze indivíduos foram analisados quanto à presença da transição A G na posição -21 da região 3' terminal do íntron 10; dos quais 36 porcento foram homozigotos para A, 43 porcento heterozigotos e 21 porcento homozigotos para G. Conclusão: Considerando as freqüências alélicas, concluímos que essas variantes correspondem a polimorfismos do gene NCF2. Suas possíveis implicações na expressão do gene NCF2 constituem objeto de pesquisa atual em nosso laboratório.

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 percent). Corynebacterium amycolatum (29.55 percent), Corynebacterium minutissimum (20.45 percent) and Corynebacterium pseudodiphtheriticum (13.63 percent) were the predominant species found in genitourinary tract. C. minutissimum (24.14 percent) and Corynebacterium propinquum (17.24 percent) in surgical and/or other skin wounds and abscesses; Corynebacterium xerosis (25 percent), C. amycolatum (21.87 percent) and C. pseudodiphtheriticum (18.75 percent) in intravenous sites; C. pseudodiphtheriticum (33.33 percent) and C. propinquum (33.33 percent) in lower respiratory tract. Microorganisms were all susceptible to vancomycin and most of the species was predominantly resistant to beta-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.