Sphygmomanometers and thermometers as potential fomites of Staphylococcus haemolyticus: biofilm formation in the presence of antibiotics

BACKGROUND The association between Staphylococcus haemolyticus and severe nosocomial infections is increasing. However, the extent to which fomites contribute to the dissemination of this pathogen through patients and hospital wards remains unknown. OBJECTIVES In the present study, sphygmomanometers and thermometers were evaluated as potential fomites of oxacillin-resistant S. haemolyticus (ORSH). The influence of oxacillin and vancomycin on biofilm formation by ORSH strains isolated from fomites was also investigated. METHODS The presence of ORSH on swabs taken from fomite surfaces in a Brazilian hospital was assessed using standard microbiological procedures. Antibiotic susceptibility profiles were determined by the disk diffusion method, and clonal distribution was assessed in pulsed-field gel electrophoresis (PFGE) assays. Minimum inhibitory concentrations (MICs) of oxacillin and vancomycin were evaluated via the broth microdilution method. Polymerase chain reaction (PCR) assays were performed to detect the mecA and icaAD genes. ORSH strains grown in media containing 1/4 MIC of vancomycin or oxacillin were investigated for slime production and biofilm formation on glass, polystyrene and polyurethane catheter surfaces. FINDINGS ORSH strains comprising five distinct PFGE types were isolated from sphygmomanometers (n = 5) and a thermometer (n = 1) used in intensive care units and surgical wards. ORSH strains isolated from fomites showed susceptibility to only linezolid and vancomycin and were characterised as multi-drug resistant (MDR). Slime production, biofilm formation and the survival of sessile bacteria differed and were independent of the presence of the icaAD and mecA genes, PFGE type and subtype. Vancomycin and oxacillin did not inhibit biofilm formation by vancomycin-susceptible ORSH strains on abiotic surfaces, including on the catheter surface. Enhanced biofilm formation was observed in some situations. Moreover, a sub-lethal dose of vancomycin induced biofilm formation by an ORSH strain on polystyrene. MAIN CONCLUSIONS Sphygmomanometers and thermometers are fomites for the transmission of ORSH. A sub-lethal dose of vancomycin may favor biofilm formation by ORSH on fomites and catheter surfaces.

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23

Abstract The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p < 0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence.

Caracterización clínica y epidemiológica de pacientes con bacteriemia en la Unidad de Cuidados Intensivos de Medicina Interna y Cirugía. Hospital Roosevelt-Guatemala / Clinical and epidemiological characterization of patients with bacteremia in the Intensive Care Unit of Internal Medicine and Surgery. Roosevelt Hospital-Guatemala

Antecedentes: La bacteriemia constituye un problema de salud prioritario debido al obstáculo que impone al proceso curativo de los pacientes, involucrando al personal y a los sistemas de salud. Objetivo: Caracterizar clínica y epidemiológicamente pacientes con bacteriemia. Materiales y Métodos: Se realizó una revisión retrospectiva de pacientes con hemocultivos positivo del año 2013, en el Intensivo médico-quirúrgico, del Hospital Roosevelt, con instrumento estandarizado, que incluyó: datos demográficos, morbilidades, comorbilidades, registro de morbilidad y mortalidad. Se calcularon intervalos de confianza al 95% y odds ratio (OR). Resultados: De 47 expedientes y 87 hemocultivos, 55% fueron femeninos, con predominio de edad de 30-49 años, en su mayoría, amas de casa. El 49%, presentó una o más condiciones médicas asociadas. La mayoría de casos de bacteriemia fueron asociados a cuidados de salud, de origen secundario. El principal foco infeccioso fue respiratorio. Los principales microorganismos aislados fueron A. baumannii, K. pneumoniae y S. haemolyticus. Los procedimientos invasivos más frecuentes fueron uso de catéter venoso central y periférico. La tasa de letalidad al día 14 fue del 30%. Conclusiones: Se observó predominio de bacteriemias secundarias, asociadas a los cuidados de la salud, cuyos principales microorganismos aislados coinciden con literatura internacional. La mayor mortalidad fue observada en el sexo femenino.(AU)

Background: Bacteremia known as a major public health problem, because of the limitation it causes to the healing process among patients, involving both health care workers, and health system.Objectives: Characterize the clinical and epidemiological profile among patients with bacteremia.Materials and methods: A retrospective review was made, including positive blood culture patients, admitted to the medical and surgical Intensive Care Unit during 2013, with a standardized instrument which included: demographical data, morbidities and co-morbidities, including a morbidity and morta-lity. The statistics included 95% confidence intervals and odds ratio (OR).Results: Of 47 clinical files, 87 blood cultures, 55% were females. The mostly affected age group was the one within 30-49 years, mainly housewives. 49% presented one or more than one associated con-dition. Most cases of bacteremia were secondary, nosocomial and health care associated. The main origin was the respiratory tract. Main microorganisms isolated were A. baumannii, K. pneumoniae and S. haemolyticus. The most frequent invasive dispositive was central and peripheral venous catheteri-zation. The mortality rate at day 14 was 30%.Conclusions: A predominance of secondary bacteremia, health care associated was observed, who-se main isolated microorganisms agree with international literature. The highest mortality rate was observed in the female sex (AU)

Characterization of mannitol-fermenting methicillin-resistant staphylococci isolated from pigs in Nigeria

This study was conducted to determine the species distribution, antimicrobial resistance pheno- and genotypes and virulence traits of mannitol-positive methicillin-resistant staphylococci (MRS) isolated from pigs in Nsukka agricultural zone, Nigeria. Twenty mannitol-positive methicillin-resistant coagulase-negative staphylococcal (MRCoNS) strains harboring the mecA gene were detected among the 64 Staphylococcus isolates from 291 pigs. A total of 4 species were identified among the MRCoNS isolates, namely, Staphylococcus sciuri (10 strains), Staphylococcus lentus (6 strains), Staphylococcus cohnii (3 strains) and Staphylococcus haemolyticus (one strain). All MRCoNS isolates were multidrug-resistant. In addition to β-lactams, the strains were resistant to fusidic acid (85%), tetracycline (75%), streptomycin (65%), ciprofloxacin (65%), and trimethoprim/sulphamethoxazole (60%). In addition to the mecA and blaZ genes, other antimicrobial resistance genes detected were tet(K), tet(M), tet(L), erm(B), erm(C), aacA-aphD, aphA3, str, dfrK, dfrG, cat_pC221, and cat_pC223. Thirteen isolates were found to be ciprofloxacin-resistant, and all harbored a Ser84Leu mutation within the QRDR of the GyrA protein, with 3 isolates showing 2 extra substitutions, Ser98Ile and Arg100Lys (one strain) and Glu88Asp and Asp96Thr (2 strains). A phylogenetic tree of the QRDR nucleotide sequences in the gyrA gene revealed a high nucleotide diversity, with several major clusters not associated with the bacterial species. Our study highlights the possibility of transfer of mecA ...

Conduta em infecções relacionadas a cateter venoso central em um hospital de referência / Care conduct for central venous catheter-related infectionsat an excellence hospital

Objetivos: avaliar a adesão às recomendações para diagnóstico de sepse relacionada a cateter (SRC), verificando a realização simultânea cultura de ponta de cateter (CPC) e hemocultura de sangue periférico (HP), em um hospital de referência. Métodos: trata-se de estudo transversal, realizado no Hospital das Cínicas da Universidade Federal de Minas Gerais, no período de janeiro de 2007 a outubro de 2009. Os dados foram coletados por profissionais especializados da Comissão de Controle de Infecção Hospitalar. Os critérios de base basearam-se nos critérios de notificação do National Healthcare Safety Network e diretrizes da Infectious Diseases Society of America (IDSA). Os dados foram digitados e analisados pelo Statistical Package for the Social Sciences (SPSS) versão 14.0. Resultados: de 683 CPC com crescimento de microrganismos, apenas 220 (32,2%) apresentaram isolamento de microrganismo em HP concomitante. Desses 220 casos, 74,1% apresentaram crescimento do mesmo microrganismo, com mesmo perfil fenotípico, em ambas as amostras. Nos casos de HP com resultado negativo e casos em que a HP não foi realizada, antimicrobianos foram prescritos em 25,7 e 31,5% dos casos, respectivamente, embora não tenha havido critérios para definição de SRC. Conclusão: apenas da recomendação de realização de CPC pareada com HP, este estudo reflete a prática de realização de CPC isolada e pode estar relacionada ao uso inapropriado de antimicrobianos, aumentando custos da assistência e favorecendo a seleção de resistência bacteriana. O diagnóstico e tratamento da SRC devem ser melhorados e os profissionais devem ser conscientizados das práticas adequadas de manejo de cateter venoso central...

Objectives: This study aims to assess compliance with recommendations for the diagnosis of catheter-related bloodstream infection (CRBSI) at an excellence hospital by verifying simultaneous performance of catheter tip culture (CTC) and peripheral blood culture (PBC). Methods: This is a cross-sectional study conducted at UFMG University Hospital from January 2007 through October 2009. Data were collected by specialized professionals of the Hospital Infection Control Committee. The notification criteria followed those prescribed by the National Healthcare Safety Network and the Infectious Diseases Society of America (IDSA). Database and statistical analysis was performed using SPSS (Statistical Package for the Social Sciences) version 14.0. Results: Concurrent peripheral blood culture was performed for only 220 (32.2%) of the 683 CTC samples presenting microorganism growth. This points to low compliance with the existing guidelines. Out of the 220 positive CTC paired with PBC results, 74.1% presented the same microorganism, with the same phenotypic profile in both samples. As for negative PBC results and no blood culture testing, antibiotics were prescribed in 25.7 and 31.5% of the cases respectively, despite the inexistence of criteria to determine CRBSI. Conclusions: Despite recommendations for pairing CTC and PBC results, this study points to the common practice of performing isolated CTC tests. This may lead to inappropriate use of antimicrobials, increasing health care costs and selection of resistant bacteria. CRBSI diagnosis and treatment should be improved, and professionals should be aware of adequate practices and management of central venous catheter...

Intravenous device associated blood stream staphylococcal infection in paediatric patients.

Background & objectives: Intravenous device (IVD) associated nosocomial blood stream infections due to staphylococci are major cause of morbidity and mortality. The present study was carried out to assess the frequency of staphylococcal IVD associated infections in a paediatric ward of a tertiary case hospital. Prevalence of resistance to commonly used antimicrobials in hospital acquired staphylococcal isolates was also tested. Methods: Children admitted in paediatric wards with IVD for more than 48 h were enrolled. Blood, IVD tip at the time of removal, skin swab at the site of insertion of IVD and nasal swab were collected and cultured by standard protocol. All staphylococcal isolates from any source were analyzed for antimicrobial susceptibility by disk diffusion method. Genotyping matching of those staphylococcal isolates was done which were isolated from different sites of the same patient, but were phonotypically similar. Genotype of blood isolate was compared with genotype of isolate from nose/IVD/skin. Results: Staphylococcus aureus was the most frequent blood isolate (8.7%) followed by Candida (2.9%), coagulase negative staphylococci (CoNS 2.6%), Pseudomonas spp. (0.4%), Klebsiella spp. (0.3%) and Escherichia coli (0.1%). Isolation of microorganisms from blood was significantly higher in patients whose skin, IVD and nose were colonized by same microorganism (P<0.001). None of the staphylococcal isolate was found to be resistant to glycopeptides (vancomycin and teicoplanin). High penicillin and oxacillin resistance was present in both S. aureus (penicillin resistance; 76.8%, oxacillin resistance; 66.7%) and CoNS (penicillin resistance; 73.3%, oxacillin resistance; 60.0%). Among CoNS biotypes, S. haemolyticus was commonest blood isolate while S. epidermidis was commonest isolate from Skin/nose. Only 33.3 per cent of S. aureus blood stream infections and most of S. epidermidis and S. haemolyticus blood infections were IVD associated. Interpretation & conclusions: Staphylococci were the major causative agent of nosocomial blood stream infections. All episodes of septicaemia due to S. epidermidis and S. haemolyticus were IVD associated while only 1/3 of S. aureus septicaemia was IVD associated.

Primer informe de staphylococcus haemolyticus con susceptibilidad reducida a vancomicina aislado de un paciente con neuroinfección neonatal en una institución mexicana / Staphylococcus haemolyticus with reduced susceptibility to vancomycin isolated from a patient with neonatal meningitis in a Mexican medical facility

La susceptibilidad reducida a vancomicina ha sido encontrada en estudios previos de aislamientos clínicos de pacientes con evolución médica inadecuada. Presentamos un caso con aislamiento de una cepa de staphylococcus haemolyticus con susceptibilidad reducida a vancomicina obtenida de un paciente recién nacido con neuroinfección a los 17 días de vida con evolución clínica adecuada después de 21 días de tratamiento. Se realizó análisis de susceptibilidad intermedia a 44 cepas de staphylococcus coagulasa negativa mediante las técnicas descritas por Wong (método de disco en agar adicionado con sal de vancomicina en concentración ≥ de 8 μg/ml en el que se demuestra satelitismo alrededor de un disco de aztreonam). La cepa fue susceptible a vancomicina al analizar la sensibilidad por un método automatizado (Sistema MicroScanR, Dade Behring). Este es el primer informe de heteroresistencia en México y una alerta temprana de la posible emergencia de staphylococcus con algún tipo de resistencia a vancomicina.

Reduced susceptibility to vancomycin has been reported among clinical isolates of Staphylococcus in previous studies. The present study describes a heteroresistant Staphylococci strain from the cerebrospinal fluid of a 17 day-old premature male infant with neonatal meningitis. Screening was done for 44 strains of coagulase-negative staphylococci using Wong 's techniques (Disk-agar method with vancomycin-salt agar to demonstrate satellitism around an aztreonam disk). Strains were susceptible to vancomycin as disclosed by an automated antimicrobial susceptibly test (Microscan System Dade Behring). This is the first report of heterogeneous resistance to vancomycin in Mexico and an early warning for the possible emergence of vancomycin resistance among coagulase-negative staphylococcus in our country.