Prevalence of Methicillin-Resistant Staphylococci on a Farm: Staff can Harbour MRS When Animals do Not

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic similarity between staphylococcus sp isolated from human and hospital settings, and susceptibility to different antimicrobials

Foram coletadas 143 amostras de mãos de humanos e camas hospitalares, através de swabs no caldo BHI, em um hospital escola da cidade de Ribeirão Preto/SP. As amostras coletadas foram incubadas a 37ºC por 24 horas e após este período as culturas foram semeadas em placas de Petri contendo agar Staphylococcus Médium 110. As colônias típicas do gênero Staphylococcus foram colhidas e estocados a 4ºC até o momento de elaboração das provas de catalase, manitol, hemólise, DNAse e coagulase. As cepas isoladas foram analisadas através da técnica de RAPD-PCR para verificar o grau de similaridade. A sensibilidade das cepas isoladas foi testada frente a 10 diferentes antibióticos. Das 92 cepas de Staphylococcus sp isoladas, 67 (72,8%) foram identificados como Staphylococcus coagulase-negativas e 25 (27,2%) como Staphylococcus coagulase-positivas. A análise de similaridade mostrou uma grande heterogeneidade entre as cepas, entretanto foram isoladas algumas cepas com 100% de similaridade. Resistência a oxacilina foi encontrada em 39 (42%) cepas. Duas cepas de estafilococos coagulase-negativos mostraram-se resistentes a vancomicina. Onze cepas (12%) de estafilococos foram consideradas multirresistentes. Medidas de desinfecção das mãos de pessoal e dos leitos hospitalares e a racionalização do uso indiscriminado de antibióticos podem contribuir para a queda da transmissão de patógenos e diminuição da pressão de seleção, e conseqüentemente diminuindo a freqüência e letalidade das infecções nosocomiais.

Detection of mixed microbial biofilms on central venous catheters removed from Intensive care Unit Patients

Cateteres venosos centrais inseridos em pacientes internados em unidade de terapia intensiva foram avaliados por métodos microbiológicos (cultura semi-quantitativa) e microscopia eletrônica de varredura a fim de detectar adesão microbiana e correlacionar com a cultura de sangue. Durante o período de estudo, foram avaliados 59 pacientes com cateter venoso central. A idade dos pacientes, sexo, sítio de inserção e tempo de permanência do cateter foram anotados. O cateter era de poliuretano não tunelizado e de único lúmen. O sangue para cultura foi coletado no momento da remoção do cateter. de 63 pontas de cateteres, 30 (47,6%) foram colonizadas e a infecção encontrada em 5 (23,8%) cateteres. A infecção foi mais prevalente em 26 pacientes (41,3%) com cateteres inseridos em veia subclávia do que nos 3 (3,2%) inseridos em veia jugular. A infecção foi observada com mais freqüência em cateteres com tempo de permanência maior do que sete dias. Os microrganismos isolados incluíram 32 estafilococos coagulase-negativa (29,7%), 61 bactérias Gram-negativas (52,9%), 9 estafilcocos coagulase-positiva (8,3%) e 3 leveduras (2,7%). Como agentes causais de infecções em unidade de terapia intensiva foram isolados E. aerogenes, P. aeruginosa, A. baumannii. Os antimicrobianos com maior atividade in vitro contra as bactérias Gram-negativas foram o imipenem e contra as Gram-positivas vancomicina, cefepime, penicilina, rifampicina e tetraciclina. As análises por microscopia eletrônica de varredura revelaram biofilmes sobre a superfície de todos os cateteres examinados.

Stpahylococcus aureus biofilms on central venous haemodialysis catheters

As infecções devido a biofilmes bacterianos são comuns em pacientes sob tratamento em hemodiálise. Neste estudo, 16 pacientes (7 homens, 9 mulheres, de 22 a 81 anos, média 50 anos de idade), com um total de 25 cateteres de hemodiálise (3 de triplo-lúmen e 22 de duplo-lúmen) de poliuretano inseridos em veia subclávia foram estudados. Os cateteres permaneceram no local de 3 a 91 dias (média de 47 dias). Os cateteres foram removidos devido ao: mau funcionamento (44%), suspeita de infecção relacionada ao cateter (20%), viabilidade de um acesso permanente (16%), remoção acidental (12%), sinais e sintomas de infecção no local da inserção do cateter (4%) e contaminação exógena (4%). Culturas positivas de ponta foram observadas em sete cateteres (28%), concomitantemente com três culturas positivas de sangue. Das culturas de sangue foram identificados Staphylococcus aureus (12%) e de uma das conexões foi isolado S. aureus. Biofilmes foram observados sobre todas as pontas de cateteres. Os S. aureus isolados do sangue e cateter (ponta e conexão) eram resistentes a pencilina e sensíveis a azitromicina, ciprofloxacina, clindamicina, cloranfenicol, gentamicina, oxacilina, rifampicina, sulfametoxazole, tetraciclina e vancomicina. As cepas de S. aureus isoladas de sangue, ponta de cateter e conexão foram consideradas idênticas devido à coincidência do perfil de sensibilidade. E similaridade genética, avaliada por meio de ribotipagem.

Prevalência e susceptibilidade antimicrobiana de Staphylococcusspp. em quadros de saúde e doença periodontal

The aim of this study was determine the prevalence and antimicrobial susceptibility of Staphylococcus spp. from patients with periodontal disease and periodontally healthy, correlate them with factors to host, local environment and traits of the diseases. To this, thirty adults from 19 to 55 years old were selected. They had not periodontal treatment and no antibiotic or antimicrobial was administered during three previous months. From these individuals, sites periodontally healthy, with chronic gingivitis and/or periodontitis were analyzed. Eighteen subgingival dental biofilm samples were collected through sterile paper points being six from each tooth randomly selected, representing conditions mentioned. They were transported to Oral Microbiology laboratory, plated onto Mannitol Salt Agar (MSA) and incubated at 370C in air for 48 h. Staphylococcus spp. were identified by colonial morphology, Gram stain, catalase reaction, susceptibility to bacitracin and coagulase activity. After identification, strains were submitted to the antibiotic susceptibility test with 12 antimicrobials, based on Kirby-Bauer technique. To establish the relation between coagulase-negative Staphylococcus (CSN) presence and their infection levels and host factors, local environment and traits of diseases were used Chi-square, Mann-Whitney and Kruskal-Wallis tests to a confidence level of 95%. 86,7% subjects harbored CSN in 11,7% periodontal sites. These prevalence were 12,1% in healthy sites, 11,7% in chronic gingivitis, 13,5% in slight chronic periodontitis, 6,75% in moderate chronic periodontitis and in sites with advance chronic periodontitis was not isolated CSN, without difference among them (p = 0,672). There was no significant difference to presence and infection levels of CSN as related to host factors, local environm ent and traits of the diseases. Amongst the 74 samples of CSN isolated, the biggest resistance was observed to penicillin (55,4%), erythromycin (32,4%), tetracycline (12,16%) and clindamycin (9,4%). 5,3% of the isolates were resistant to oxacilin and methicillin. No resistance was observed to ciprofloxacin, rifampicin and vancomycin. It was concluded that staphylococci are found in low numbers in healthy or sick periodontal sites in a similar ratio. However, a trend was observed to a reduction in staphylococci occurrence toward more advanced stages of the disease. This low prevalence was not related to any variables analyzed. Susceptibility profile to antibiotics demonstrates a raised resistance to penicillin and a low one to methicillin. To erythromycin, tetracycline and clindamycin was observed a significant resistance

The role of virulence factors in the outcome of staphylococcal peritonitis in CAPD patients

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA): molecular background, virulence, and relevance for public health

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Risk factors for recovery of Imipenem-or ceftazidime-resistant Pseudomonas aeruginosa among patients admitted to a teaching hospital in Brazil

background. The prevalence of resistance to imipenem and ceftazidime among Pseudomonas aeruginosa isolates is increasing worldwide.objective. Risk factors for nosocomial recovery ( defined as the finding of culture- positive isolates after hospital admission) of imipenemresistant P. aeruginosa ( IRPA) and ceftazidime- resistant P. aeruginosa ( CRPA) were determined.design. Two separate case- control studies were conducted. Control subjects were matched to case patients ( ratio, 2: 1) on the basis of admission to the same ward at the same time as the case patient. Variables investigated included demographic characteristics, comorbid conditions, and the classes of antimicrobials used.setting. The study was conducted in a 400- bed general teaching hospital in Campinas, Brazil that has 14,500 admissions per year. Case patients and control subjects were selected from persons who were admitted to the hospital during 1992 - 2002.results. IRPA and CRPA isolates were obtained from 108 and 55 patients, respectively. Statistically significant risk factors for acquisition of IRPA were previous admission to another hospital ( odds ratio [ OR], 4.21 [ 95% confidence interval {CI}, 1.40- 12.66];), hemodialysis Pp. 01 ( OR, 7.79 [ 95% CI, 1.59- 38.16];), and therapy with imipenem ( OR, 18.51 [ 95% CI, 6.30- 54.43];), amikacin ( OR, 3.22 Pp. 01 P !.001 [ 95% CI, 1.40- 7.41];), and/ or vancomycin ( OR, 2.48 [ 95% CI, 1.08- 5.64];). Risk factors for recovery of CRPA were Pp. 005 Pp. 03 previous admission to another hospital ( OR, 18.69 [ 95% CI, 2.00- 174.28];) and amikacin use ( OR, 3.69 [ 95% CI, 1.32- 10.35]; Pp. 01). Pp. 01conclusion. Our study suggests a definite role for several classes of antimicrobials as risk factors for recovery of IRPA but not for recovery of CRPA. Limiting the use of only imipenem and ceftazidime may not be a wise strategy to contain the spread of resistant P. aeruginosa strains.

Predictive factors of outcome following staphylococcal peritonitis in continuous ambulatory peritoneal dialysis

Background and aims: Staphylococcus epidermidis and other coagulase-negative staphylococci (CoNS) are the most common agents of continuous ambulatory peritoneal dialysis (CAPD) peritonitis. Episodes caused by Staphylococcus aureus evolve with a high method failure rate while CoNS peritonitis is generally benign. The purpose of this study was to compare episodes of peritonitis caused by CoNS species and S. aureus to evaluate the microbiological and host factors that affect outcome. Material and methods: Microbiological and clinical data were retrospectively studied from 86 new episodes of peritonitis caused by staphylococci species between January 1996 and December 2000 in a university dialysis center. The influence of microbiological and host factors (age, sex, diabetes, use of vancomycin, exchange system and treatment time on CAPD) was analyzed by logistic regression model. The clinical outcome was classified into two results (resolution and non-resolution). Results: the odds of peritonitis resolution were not influenced by host factors. Oxacillin susceptibility was present in 30 of 35 S. aureus lineages and 22 of 51 CoNS (p = 0.001). There were 32 of 52 (61.5%) episodes caused by oxacillin-susceptible and 20 of 34 (58.8%) by oxacillin-resistant lineages resolved (p = 0.9713). of the 35 cases caused by S. aureus, 17 (48.6%) resolved and among 51 CoNS episodes 40 (78.4%) resolved. Resolution odds were 7.1 times higher for S. epidermidis than S. aureus (p = 0.0278), while other CoNS had 7.6 times higher odds resolution than S. epidermidis cases (p = 0.052). Episodes caused by S. haemolyticus had similar resolution odds to S. epidermidis (p = 0.859). Conclusions: S. aureus etiology is an independent factor associated with peritonitis non-resolution in CAPD, while S. epidermidis and S. haemolyticus have a lower resolution rate than other CoNS. Possibly the aggressive nature of these agents, particularly S. aureus, can be explained by their recognized pathogenic factors, more than antibiotic resistance.

Comparison of teicoplanin disk diffusion and broth microdilution methods against clinical isolates of Staphylococcus aureus and S. epidermidis

The CLSI M100-S19 document has recommended the disuse of vancomycin disks for staphylococci and informed that studies on the action of teicoplanin in disk-diffusion testing should be performed. We describe the comparison of two methods, disk diffusion and broth microdilution, for determining teicoplanin susceptibility in clinical isolates of staphylococci. Overall results showed an aggregation rate of 96.8%; Staphylococcus aureus showed total agreement while S. epidermidis showed 93.8% of agreement. According to these local results, disk diffusion can still be employed to teicoplanin susceptibility determination for staphylococci in our institution.

Identification and antimicrobial susceptibility of Staphylococcus from home-treated peritoneal dialysis patients

Staphylococcus aureus is the main agent of infections during peritoneal dialysis (PD). The presence of S. aureus in the nasal cavity has been extensively studied and suggested as a risk factor of dialysis-related infections, whereas coagulase-negative Staphylococcus (CNS) species are frequently considered part of the normal human microbiota. The aim of this study was to identify Staphylococcus in the nasal cavity, pericatheter skin and peritoneal effluent from PD patients, as well as to evaluate the antimicrobial activity evolution in vitro. Thirty-two chronic PD patients were observed during 12 months and had nasal and pericatheter skin samples collected for culture. When peritonitis was detected, samples were also collected from the peritoneal effluent for culture. The activity of several antimicrobial drugs (penicillin G, oxacillin, cephalothin, ofloxacin, netilmicin and vancomycin) against different Staphylococcus species was measured by using the agar drug diffusion assay (Kirby-Bauer method). Staphylococcus was separated into S. aureus, S. epidermidis and other CNS species in order to determine the in vitro resistance level. S. epidermidis resistance to oxacillin progressively increased during the study period (p < 0.05). Resistance to ofloxacin was inexpressive, whereas resistance to netilmicin and vancomycin was not detected. of the oxacillin-resistant species (n = 74), 83% were S. epidermidis, 13% other CNS and 4% S. aureus (p < 0.05). Regarding multidrug resistant strains (n = 45), 82% were S. epidermidis, 13% other CNS, and 5% S. aureus (p < 0.05). This study shows the relevance of resistance to oxacillin and CNS multi-drug resistance, particularly concerning S. epidermidis, in PD patients.

Estudo sobre a resistencia aos antimicrobianos em bacterias isoladas de pacientes hospitalizados (Botucatu, 1988-1992)

Since 1988 to 1992, a study about susceptibility to antimicrobial drugs of bacterias isolated from hospitalized patients was performed. The compared susceptibility to important drugs (ampicillin, cephalotin, cefoxitin, ceftaxizime, ceftriaxone, aztreonam, gentamicin, amikacin, pefloxacin, ciprofloxacin, imipenem, oxacillin and vancomycin) was investigated in 1200 strains (300 of each specie) of the prevalent bacterias: E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and S. aureus. Minimal inhibitory concentration (MIC) was determined by agar dilution method, using from 0.05 to 256 mcg of each drug per ml of culture medium (Mueller-Hinton). Ranges of MIC, MIC(50%), MIC(90%) and the proportion of resistant strains were determined and permitted to know the 4 drugs that were found to be more active against bacterias; the CIM(90%) values are: E. coli - aztreonam (0.1 mcg/ml), pefloxacin (0.1), ceftazidime (0.25) and ceftriaxone (0.05); K. pneumoniae-aztreonam (0.25) ceftriaxone (0.25), ceftazidime (0.5) and pefloxacin (2.0); P. aeruginosa-imipenem (4.0), aztreonam (16), ceftazidime (16) and ciprofloxacin (16); S. aureus-vancomycin (1.01, ciprofloxacin (8, 0), amikacin (128) and cephalothin (128 mg/ml). The better 'in vitro' antibacterial activity observed was related to: aztreonam (77-100% of the sensitive strains), ceftazidime (50-99,7%), pefloxacin (73-99,7%), ciprofloxacin (80%), imipenem (93%) and vancomycin (100%).

Ocorrência e determinação do perfil de sensibilidade às drogas das cepas de Staphylococcus aureus isoladas de fossas nasais e orofaringe dos servidores hospitalares

Staphylococcus aureus is a very important hospital and community pathogen. This species is related to supurative disease, systemic and widespread metastatic lesions. The ability of S. aureus to develop resistance to antibiotics, more recently to methicillin, associates this bacteria with epidemic outbreaks of severe nosocomial infection. The source of staphylococcal infection is a patient with a staphylococcal lesion or a career member of the hospital staff. We aimed to detect the frequency of S. aureus isolated from anterior nares and oral cavities among the hospital staff in Bauru - SP, and to determine the antibiotic susceptibility of the isolates. Within 213 of the staff members analyzed. S. aureus was found in 94 (44.13%) of careers, with 47 (50%) of nasal carriers, 23 (24.4%) of oral carriers and 24 (25.5%) of both carriers. The biochemical characteristics analyzed for the species identification were similar to S. aureus ATCC 29213. All strains identified as S. aureus showed varied sensibility to the antimicrobial agents tested. No vancomicin resistant strains and only 8 (8.5%) strains with oxacilin resistance were found.

Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs

Propolis is a natural resinous substance collected by bees from tree exudates and secretions. Its antimicrobial activity has been investigated and inhibitory action on Staphylococcus aureus growth was evaluated The in vitro synergism between ethanolic extract of propolis (EEP) and antimicrobial drugs by two susceptibility tests (Kirby and Bauer and E-Test) on 25 S. aureus strains was evaluated Petri dishes with sub-inhibitory concentrations of EEP were incubated with 13 drugs using Kirby and Bauer method and synergism between EEP and five drugs [choramphenicol (CLO), gentamicin (GEN), netilmicin (NET), tetracycline (TET), and vancomycin (VAN)] was observed. Nine drugs were assayed by the E-test method and five of them exhibited a synergism [CLO, GEN, NET, TET, and clindamycin (CLI)]. The results demonstrated the synergism between EEP and antimicrobial drugs, especially those agents that interfere on bacterial protein synthesis.