Bloodstream infection by Acinetobacter radioresistens: the first case report in Brazil / Bacteremia por Acinetobacter radioresistens: primeiro relato de caso no Brasil

ABSTRACT This report is the description of the first case in Brazil of community-acquired bloodstream infection caused byAcinetobacter radioresistens. A 73-year-old male patient with Alzheimer's and Parkinson's disease was hospitalized and diagnosed with pneumonia at a general hospital. MacConkey agar pure culture was obtained from blood cultures. Conventional tests identified the isolate as Acinetobacter baumannii complex. However, the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) technique identified it as Acinetobacter radioresistens. The isolate was sensitive to all antibiotics tested by the disk diffusion method, including carbapenem. However, blaoxa-23 gene was detected by the polymerase chain reaction (PCR) assay. Acinetobacter radioresistens can be considered an important agent of opportunistic infections in immunocompromised patients, a potential disseminator of resistance genes.

RESUMEN Este reporte es la descripción del primer caso en Brasil de bacteriemia por Acinetobacter radioresistens adquirida en la comunidad. Paciente masculino de 73 anos de edad, portador de las enfermedades de Alzheimer y de Parkinson, fue atendido en un hospital general y diagnosticado con cuadro de neumonía. Cultivo puro en agar MacConkey fue obtenido de hemocultivos. Pruebas convencionales identificaron el aislado como complejo Acinetobacter baumannii, pero el sistema desorción/ionización láser asistida por matriz-tiempo de vuelo (MALDI-TOF) lo identificó como Acinetobacter radioresistens. El aislado se presentó sensible a todos antibióticosprobados mediante el método de difusión en disco, incluyendo los carbapenemas. Sin embargo, el gen blaoxa-23 fue detectadopor la técnica de reacción en cadena de lapolimerasa (RCP). Acinetobacter radioresistenspuedeser considerado un agente importante de infecciones oportunistas en pacientes inmunocomprometidos, un potencial diseminador de genes de resistencia.

RESUMO Este relato éa descrição do primeiro caso no Brasil de bacteremia adquirida na comunidade causada por Acinetobacter radioresistens. Paciente do sexo masculino, 73 anos de idade, portador da doença de Alzheimer e de Parkinson, foi assistido em um hospital geral e diagnosticado quadro de pneumonia. Cultura pura em ágar MacConkey foi obtida a partir de hemoculturas. Testes convencionais identificaram o isolado como complexo Acinetobacter baumannii, porém o sistema matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) identificou como Acinetobacter radioresistens. O isolado apresentou-se sensível a todos os antibióticos testados por meio da técnica do disco difusão, incluindo os carbapenens. Contudo, foi detectado o gene blaOXA23 pela técnica da reação em cadeia da polimerase (PCR). Acinetobacter radioresistens pode ser considerado um agente importante de infecções oportunistas em pacientes imunocomprometidos, um potencial disseminador de genes de resistência.

Ocorrência de Staphylococcus spp. resistente à meticilina em otite externa canina / Occurrence of methicillin-resistant Staphylococcus spp. in canine external otitis

Objetivo: O presente estudo objetivou traçar o perfil de resistência dos isolados de Staphylococcus spp. resistentes à meticilina (SMR) em cães com otite externa proveniente de atendimentos ambulatoriais ou de internação. Métodos: Isolamento e identificação bacteriológica por meio de provas bioquímicas e testes de susceptibilidade a antibacterianos. Detecção do gene mecA por PCR e determinação da concentração bactericida mínima (CBM) ao gluconato de clorexidina. Resultados: Foram coletadas 140 amostras e, destas, foram isolados 122 Staphylococcus spp. (49,4%). Dos isolados bacterianos, 14 cepas (11,47%) foram SMR (oito coagulase positiva e seis coagulase negativa), apresentando o gene mecA. A concentração bactericida mínima ao gluconato de clorexidina para os Staphylococcus spp. coagulase positiva foi de 500.000 mg/mL (0,5%) e para os coagulase negativa foi de 62.500 mg/mL (0,0625%). Cinco SMR foram positivos para o teste-D. Os SMR foram 100% sensíveis à linezolida, cloranfenicol e rifampicina. Conclusão: Apesar da baixa frequência da multirresistência encontrada, existe a necessidade de monitoramento efetivo em estirpes isoladas de animais domésticos, garantindo o sucesso do tratamento e controle da resistência bacteriana em infecções otológicas caninas.

Objective: The objective of this study is to outline the resistance profile of methicillin-resistant Staphylococcus spp. (MRS) isolates from outpatient and inpatient care dogs diagnosed with otopathy. Methods: Isolation and bacteriological identification through biochemical tests and antibacterial susceptibility testing. Detection of mecA gene by PCR and determination of minimum bactericidal concentration (CBM) to chlorhexidine gluconate. Results: 140 samples were collected and from these 122 was Staphylococcus spp. (49.4%). Of all bacterial isolates 14 (11.47%) were MRS (eight coagulase positive and six coagulase negative) with mecA gene. The minimum bactericidal concentration to chlorhexidine guconate was 500,000 mg/mL (0.5%) for coagulase positive Staphylococcus spp. and 62,500 mg/mL (0.0625%) for coagulase negative. Five MRS were positive for D-test. The MRS were 100% sensitive to linezolide, chloramphenicol and rifampicin. Conclusion: Despite the low frequency of multiressitance found, there is a need for more effective monitoring in strains isolated from domestic animals to guarantee successful treatment and control of bacterial resistance in canine otological infections.

Decreased susceptibility to chlorhexidine and distribution of qacA/B genes among coagulase-negative Staphylococcus clinical samples.

BACKGROUND: Healthcare-associated infection (HAI) is a major public health problem. As a form of prevention and control, preparations of chlorhexidine are used extensively; however, the reduction of susceptibility to chlorhexidine has been reported. The aim of this study was to investigate the susceptibility to chlorhexidine and the distribution of the qacA/B genes in 211 clinical isolates of coagulase-negative Staphylococci (CoNS). METHODS: CoNS were identified by conventional biochemical tests. Antimicrobial susceptibility was tested by disk-diffusion. Minimum inhibitory concentration (MIC) of chlorhexidine was determined by agar dilution test; detection of the qacA/B and mecA genes were evaluated by PCR. RESULTS: The most frequently isolated species were S. epidermidis, S. hominis hominis, S. auricularis, and S. haemolyticus, respectively. The strains presented a multidrug resistance profile of 87%, including methicillin resistance. Reduced susceptibility to chlorhexidine was observed in 31%. The qacA/B genes were detected in samples resistant (32/32) and susceptible (17/32) to chlorhexidine. The vast majority (94%) of the samples with reduced susceptibility to chlorhexidine were multidrug resistant. CONCLUSIONS: Our results show that qacA/B genes are not restricted to strains expressing chlorhexidine resistance. Further studies are needed to understand how the expression of these genes occurs.

Enterotoxin-Encoding Genes in Staphylococcus spp. from Food Handlers in a University Restaurant.

Food handlers carrying enterotoxin-producing Staphylococcus are a potential source of food poisoning. The aim of this study was to analyze genes encoding enterotoxins in coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS) isolated from the anterior nostrils and hands of food handlers at a university restaurant in the city of Natal, Northeast Brazil. Thirty food handlers were screened for the study. The isolates were subjected to Gram staining, a bacitracin sensitivity test, mannitol fermentation, and catalase and coagulase tests. CoNS and CoPS strains were subsequently identified by a Vitek 2 System (BioMerieux, France) and various biochemical tests. Polymerase chain reaction was used to detect genes for enterotoxins A, B, C, D, E, G, H, and I (sea, seb, sec, sed, see, seg, seh, and sei) and a disc-diffusion method was used to determine susceptibility to several classes of antimicrobials. All food handlers presented staphylococci on their hands and/or noses. The study found 58 Staphylococcus spp., of which 20.7% were CoPS and 79.3% were CoNS. S. epidermidis was the most prevalent species. Twenty-nine staphylococci (50%) were positive for one or more enterotoxin genes, and the most prevalent genes were seg and sei, each with a frequency of 29.3%. Indeed, CoNS encoded a high percentage of enterotoxin genes (43.5%). However, S. aureus encoded even more enterotoxin genes (75%). Most isolates showed sensitivity to the antibiotics used for testing, except for penicillin (only 35% sensitive). The results from this study reinforce that coagulase-negative as well as coagulase-positive staphylococci isolated from food handlers are capable of genotypic enterotoxigenicity.

Emergence of methicillin-resistant coagulase-negative staphylococci resistant to linezolid with rRNA gene C2190T and G2603T mutations.

The aim of this article were to determinate the mechanism of linezolid resistance in coagulase-negative methicillin-resistant staphylococci from hospitals in the northeast of Brazil. We identified the isolates using VITEK(®) 2 and MALDI-TOF. Susceptibility to antibiotics was measured by the disk-diffusion method and by Etest(®) . Extraction of the whole genome DNA was performed, followed by screening of all the strains for the presence of mecA and cfr genes. The domain V region of 23S rRNA gene was sequenced and then aligned with a linezolid-susceptible reference strain. Pulsed-field gel electrophoresis (PFGE) macro-restriction analysis was performed. Three linezolid-resistant Staphylococcus hominis and two linezolid-resistant Staphylococcus epidermidis strains were analyzed. The isolates showed two point mutations in the V region of the 23S rRNA gene (C2190T and G2603T). We did not detect the cfr gene in any isolate by PCR. The S. hominis showed the same pulsotype, while the S. epidermidis did not present any genetic relation to each other. In conclusion, this study revealed three S. hominis and two S. epidermidis strains with resistance to linezolid due to a double mutation (C2190T and G2603T) in the domain V of the 23S rRNA gene. For the first time, the mutation of C2190T in S. epidermidis is described. This study also revealed the clonal spread of a S. hominis pulsotype between three public hospitals in the city of Natal, Brazil. These findings highlight the importance of continued vigilance of linezolid resistance in staphylococci.

Prevalence and factors associated with wound colonization by Staphylococcus spp. and Staphylococcus aureus in hospitalized patients in inland northeastern Brazil: a cross-sectional study.

BACKGROUND: Infections by Staphylococcus spp. are often associated with wounds, especially in hospitalized patients. Wounds may be the source of bacteria causing cross-contamination, and are a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) infection. The aim of this study was to investigate the prevalence of wound colonization by Staphylococcus spp., especially S. aureus and MRSA, in hospitalized patients, and to identify the factors associated with such colonization. METHODS: This cross-sectional study enrolled patients with wounds who were hospitalized in a remote and underdeveloped inland region of northeastern Brazil with extreme poverty. Samples were collected using sterile swabs with 0.85% saline solution, and coagulase-negative Staphylococcus spp., S. aureus, and MRSA were identified using standard laboratory procedures. Data regarding the sociodemographic characteristics, antibiotic use, and comorbidities of the patients were collected using the medical records and a questionnaire. RESULTS: A total of 125 wounds were analyzed. The patients had a mean age of 63.88 years and a mean 3.84 years of school education. Eighty-one wounds (64.80%) were colonized by Staphylococcus spp. Twenty-five wounds (20%) were colonized by S. aureus, 32% of which were colonized by MRSA. Wound colonization by Staphylococcus spp. was associated with pneumonia or other respiratory disease (p = 0.03). Wound colonization by S. aureus was associated with nasal colonization by S. aureus (p < 0.001), fewer days of prior antibiotic use (p = 0.04), admission to a medical ward (p = 0.02), and age >65 years (p = 0.05). Among patients with wound colonization by MRSA, 37.50% had a history of prior antibiotic use, 75% had two or more comorbidities, 25% had cancer or diabetes, 50% had cardiovascular disease, and 50% died. CONCLUSIONS: Wounds can be the source of Staphylococcus spp. infection, and high proportions of wounds are colonized by S. aureus and MRSA. Nasal colonization by S. aureus may be a source for wound colonization by S. aureus, illustrating the importance of preventing cross-contamination in hospital environments, especially among elderly patients. Wounds should be carefully managed to prevent microbial spread, thereby assisting patient recovery and reducing healthcare costs.

Feature selection strategies for identification of Staphylococcus aureus recovered in blood cultures using FT-IR spectroscopy successive projections algorithm for variable selection: a case study.

Staphylococcus aureus is one of the leading causes of bacteremia, with high levels of accompanying morbidity and mortality. Current gold standard for the detection of S. aureus is very time-consuming, typically taking 24h or longer. We set out to determine whether Fourier-transform infrared spectroscopy (FT-IR) combined with variable selection techniques, such as, genetic algorithm-linear discriminant analysis (GA-LDA) and successive projection algorithm-linear discriminant analysis (SPA-LDA) could be applied to detect this pathogen of bloodstream infection in samples based on the unique spectral "fingerprints" of their biochemical composition. Thirty real blood samples from healthy volunteers were contaminated with five different concentrations (10(7) until 10(3) CFU/mL) of microorganism and it analyzed by IR spectroscopy. The resulting GA-LDA model successfully classified all test samples with respect to their concentration in contaminated blood using only 18 wavenumbers. Discriminant functions revealed that GA-LDA clearly segregated different microorganism concentrations and the variable selected confirmed the chemical entities associated with the microorganism. The current study indicates that IR spectroscopy with feature selection techniques have the potential to provide one rapid approach for whole-organism fingerprint diagnostic microbial directly in blood culture.