Detecção de Staphylococcus aureus e Staphylococcus aureus resistentes à meticilina em profissionais da saúde lotados no Instituto Lauro de Souza Lima, Bauru-SP / Detection of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in health care workers packed the Instituto Lauro de Souza Lima, Bauru-SP

O Staphylococcus aureus (S. aureus) é um patógeno comumente isolado de amostras biológicas humanas. É encontrado com freqüência na pele e fossas nasais de indivíduos saudáveis, podendo provocar desde simples infecções ate graves enfermidades. Cerca de 40% da população adulta saudável é portadora nasal de S. aureus e esta taxa pode ser ainda maior em ambientes hospitalares, especialmente entre os pacientes internados e equipe médica. O surgimento da resistência à meticilina, uma penicilina sintética, pelo S. aureus e sua disseminação tornaram as medidas de controle epidemiológico ainda mais importantes no que diz respeito à prevenção de infecções hospitalares e, mais recentemente, comunitárias. Profissionais da área de saúde que são portadores nasais de S. aureus e Staphylococcus aureus resistentes a meticilina (MRSA) são considerados importantes fontes de disseminação do patógeno e estão intimamente envolvidos na epidemiologia dos mesmos. Investigação constante e adoção de medidas de controle na admissão dos pacientes em áreas de alta endemicidade para MRSA, tais com CTIs e centros de dermatologia, são consideradas estratégias efetivas em termos de custo-benefício contra as ionfecções hospitalares, bem como o estudo da prevalência de MRSA em profissionais de saúde que atuam nos referidos lugares. O objetivo do estudo foi verificar a colonização por S. aureus e MRSA nas fossas nasais de profissionais das equipes médicas de enfermagem e dos laborat´rios em um hospital de dermatologia de nível terciário - Instituto Lauro de Souza Lima - Bauru/SP...

Application of PCR based - RFLP for species identification of ocular isolates of methicillin resistant staphylococci (MRS).

Background & objectives: Early detection of methicillin resistant staphylococci (MRS) from clinical specimens enables institution of appropriate antimicrobial therapy. Limited information is available on speciation of MRS. This study was undertaken to compare results of conventional and molecular methods in detection of methicillin resistance (MR) and application of PCR-restriction fragment length polymorphism (RFLP) and DNA sequencing for speciation of ocular isolates of MRS. Methods: A total of 110 consecutive ocular staphylococcal isolates were screened for MR. MRS was speciated by PCR-RFLP of gap gene and results were confirmed by DNA sequencing. All isolates were processed within 48 h of isolation. A single colony of bacterium, stocked as stab cultures in Hyer’s and Johnson agar, was stored at 40C and sub-cultured at every 15 days interval. Results: Seventy (63.6%) of 110 isolates were identified as MRS and 40 (36.4%) were MSS by conventional and molecular method (100% correlation). Of the 70 MRS, 18 (25.7%) were Staphylococcus aureus, remaining 52 (74.3%) were CNS by conventional and molecular method (100% correlation). PCR-RFLP of gap gene identified 18 (25.71%) MRS as S. aureus, 11 (15.71%) S. epidermidis, 27 (38.57%) S. haemolyticus, 6 (8.57%) S. cohnii subsp. urealyticum, 6 (8.57%) S. equorum, 1 (1.42%) S. xylosus and 1 (1.42%) S. hominis. Interpretation & conclusions: Overall rate of isolation MRS was 63.6 per cent and were predominantly isolated from conjunctival swab (23.6%) and donor corneal scleral rim (23.6%) of non hospitalized patients indicating their community origin. Detection of MR by mecA gene was easier and less time consuming compared to conventional methods. Speciation of MRS was possible by gap gene PCR - RFLP and the predominant MRS in our study was S. haemolyticus.

Emergence of methicilllin resistant Staphylococcus aureus (MRSA) associated with wound infections.

In a hospital setting antimicrobial resistant organisms especially Methicillin resistant Staphylococcus aureus (MRSA) has emerged as an important variable influencing patients' outcome and overall resource utilisation. The present study was undertaken to find out the proportion of MRSA and other organisms and their antimicrobial resistance pattern in admitted cases with postoperative wound infections. A total of 50 wound swabs were collected irrespective of age and sex of the patients from National Institute of Traumatology and Orthopaedics Rehabilitation (NITOR). The laboratory work was performed in the department of microbiology of National Institute of Cardiovascular Diseases (NICVD). Isolation, identification and susceptibility testing was done according to the guideline of the National Committee for Clinical Laboratory Standards (NCCLS, 1998). Out of the 50 samples 34 yielded growths of which 15 had growth of single organism and 19 had mixed growth of 2 to 3 organisms. Four different types of organisms were identified. Highest percentage was Escherichia coli 55.9%, followed by Pseudomonas sp. 52.9%, Proteus sp. 38.2%, and Staphylococcus aureus 17.6%. Of the 6 isolates of S aureus 5 (83.3%) were MRSA. Therefore it can be concluded that MRSA is existing in the hospital premises of NITOR, which can endanger the life of many. This study emphasises that susceptibility testing of all clinical isolates is essential to reduce the morbidity, mortality and longer duration of hospital stay. In addition proper management of the cases can decrease the spread of multiple drug resistant organisms in the community.

Determinación de los estafilococos meticilina resistentes para el uso racioanl de vancomicina / Determination of methycillin-resistant staphylococci and rational use of vancomycin

Se realió un estudio de 100 cepas de estafilococos procedentes de hemocultivos y cultivos de secreciones, utilizando los procedimientos y criterios del Comité Nacional de Estánderes para el Laboratorio Clínico (NCCLS, National Committee for Clinical Laboratory Standars, 55 cepas estudiadas fueron de S. aureus y 45 cepas de Staphylococcus coagulasanegativos, de ellas 47 por ciento fueron de S. epidermidis. Se encontró resistencia a la oxacilina en el 60 por ciento de las cepas de S. aureus y en 57 por ciento de S. epidermidis. La resistencia intrínseca real a meticilina, representada por la oxacilina, fue de 58 por ciento para S. aureus., 19 por ciednrto para S. epidermidis y 8 por ciento para los otros estafilococos coagulasanegativos. Se concluye que los estafilococos meticilina-resistentes están en aumento costante edn el Hospital Rebagliati y qaue los Stahylococos coagulasanegativos, que eran considerados no patógenos, en la actualidad son un importante agente de infección nosocomial por lo que es necesario ahora la valoración de la resistencia verdadera de los estafilococos para orientar la terapéutica y el uso racional de vancomicina

Epidemiological typing of methicillin-resistant Staphylococcus aureus outbreak isolates by pulsed-field gel electrophoresis and antibiogram

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens. In April 1997, there were five MRSA-infected patients among 16 patients in the Neonatal Intensive Care Unit (NICU), Seoul National University Hospital, which is a tertiary-care hospital with 1,500 beds. The infections had spread from twin patients with MRSA who had transferred from Hospital C. MRSA was isolated from the axilla of 15 (94%) of the 16 patients, including the two patients with obvious infections. Three (19%) of 16 doctors and nine (30%) of 30 nurses had MRSA colonization of the anterior nares. Six different PFGE patterns (A through F) were identified in the 53 isolates of MRSA tested. Twelve of 13 isolates from infected sites of five patients showed pattern F. Three MRSA strains obtained from hospital C showed closely or possibly related pattern F. MRSA of type F was isolated from three of 16 patients' axilla, and one of 3 doctors' and three of 30 nurses' nasal swabs. The antibiogram code for 12 of 13 MRSA isolates from five infected patients was 66,754. PFGE patterns of these isolates were either F, F1, F2 or Fa. Only one of three strains isolated from clinical specimens of patients in Hospital C showed the antibiogram code 66754, although they were all PFGE types F1 and Fa. In conclusion, the presumptive sources of the outbreak of MRSA infection in NICU were the twin patients transferred from hospital C. Antibiogram correlated reasonably well to the PFGE type. An effective notification system is needed when a MRSA-infected patient is transferred to another hospital to control the spread of the infection.

Why do antimicrobial agents become ineffectual?

Antibiotic resistance has evolved over the past 50 years from a merely microbiological curiosity to a serious medical problem in hospitals all over the world. Resistance has been reported in almost all species of gram-positive and -negative bacteria to various classes of antibiotics including recently developed ones. Bacteria acquire resistance by reducing permeability and intracellular accumulation, by alteration of targets of antibiotic action, and by enzymatic modification of antibiotics. Inappropriate use of an antibiotic selects resistant strains much more frequently. Once resistant bacteria has emerged, the resistance can be transferred to other bacteria by various mechanisms, resulting in multiresistant strains. MRSA is one of the typical multiresistant nosocomial pathogens. A study of the PFGE pattern of endonuclease-digested chromosomal DNA showed that MRSA of a few clones were disseminated among newborns in the NICU of a Japanese hospital. In this regard, it is important to choose appropriate antibiotics and then after some time, to change to other classes to reduce the selection of resistant strains. Since the development of epoch-making new antibiotics is not expected in the near future, it has become very important to use existing antibiotics prudently based on mechanisms of antibiotic action and bacterial resistance. Control of nosocomial infection is also very important to reduce further spread of resistant bacteria.

Acquisition of methicillin resistance and progression of multiantibiotic resistance in methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) produces specific penicillin-binding protein, PBP2', which shows remarkably low affinities to most beta-lactam antibiotics except those such as penicillin G and ampicillin. The region surrounding mecA has been called additional DNA or mec and is thought to be of extraspecies origin. From the study of mec, we found that mec is a novel mobile genetic element and designated as staphylococcal cassette chromosome mec (SCCmec). There are three types of SCCmec. In the past decades, MRSA has become resistant to many antibiotics, such as carbapenems, new quinolones, and minocycline etc. It seems to be a characteristic of MRSA to acquire multi-resistance by accumulating multiple resistance genes around the mecA gene inside SCCmec.

Estudio molecular de 6 episodios de infección intrahospitalaria causados por staphylococcus aureus meticilino-resistente / Molecular study of 6 episodes of intrahospitalary infection due to methicillin resistant staphylococcus aureus

A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach-plasmids identification, restriction lengght polymorphism DNA analysis and random amplified polymorphic DNA for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotipic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied