Isolation, Detection and Molecular Characterization of Staphylococcus aureus from Postoperative Infections

Post operative infections that occur after surgical procedures can cause a lot of complications like sepsis, organ failure or even death. These are the third most commonly reported healthcare associated infection. The most common cause of wound infection regardless of procedure performed remains gram-positive cocci which comprise more than 50% of all infections. Specifically, Staphylococcus aureus and coagulase-negative staphylococci are the most frequent organisms isolated from a wound infection. There has been an increasing incidence of MRSA strains reported in hospitals across the globe. The main aim of our study is isolation, detection and molecular characterization of Staphylococcus aureus from postoperative infections. Samples were collected from post operative patients with infected wounds. The area around the wound was cleaned. Exudates were collected from the wound with a sterile swab stick. The samples were inoculated on different solid culture mediums and the plates were incubated in the presence of oxygen at 37°C overnight. There were many standard procedures done in which tube coagulase was taken as the main criteria. Antibiotic susceptibility testing was done by Kirby Bauer method following Clinical and Laboratory Standards Institute (CLSI) guidelines using commercially available cefoxitin (30 μg) disc (HiMedia) and the results were compared with Staphylococcus aureus ATCC 25923 and MRSA ATCC 43300 control strains. The MRSA strains were identified and detection of Mec A gene that codes for methicillin resistance is done using PCR technique.

Aislamiento e identificación de bacterias con potencial nosocomial procedentes de ambientes y superficies de una clínica veterinaria Universitaria del Área Metropolitana del Valle de Aburrá, Antioquia-Colombia / Isolation and identification of bacteria with nosocomial potential from environments and surfaces of a veterinary university clinic of Metropolitan area of Aburra Valley Antioquia-Colombia

Introducción: Las infecciones nosocomiales son aquellas adquiridas por los pacientes durante la hospitalización. Son de gran importancia en medicina humana pero aún se desconoce cuál es su papel en medicina veterinaria. Objetivo: Identificar la presencia de bacterias asociadas a infecciones hospitalarias en ambientes y superficies en una clínica veterinaria. Materiales y métodos: Se realizaron dos muestreos, se determinó a través de sedimentación y torunda la presencia de bacterias en el ambiente y las superficies de las 8 unidades de la clínica veterinaria. La presencia de nosocomiales se determinó por el crecimiento y purificación en medios diferenciales, la identificación se hizo por descripción macroscópica de las colonias y tinción de Gram y posteriormente se realizó una caracterización bioquímicamente por medio del API20E y API50 CH/E y un antibiograma en las cepas relacionadas con resistencia a antibióticos. Resultados: Se obtuvo 95 aislados y se logró determinar la presencia de 28 agentes potencialmente nosocomiales, donde se destaca la presencia de Pseudomonas aeruginosa, Proteus sp. y Staphylococcus sp. microorganismos relacionados con infecciones asociadas a hospitales veterinarios. Conclusiones: Se realiza la primera aproximación a este tipo de infecciones en hospitales veterinarios en Antioquia, y se evidencia la circulación en ambiente y superficies de potenciales bacterias nosocomiales en la clínica veterinaria.

Introduction: Care associated infections are of importance in human medicine but few is known in veterinary medicine. Aims: To identify pathogenic bacteria in surfaces of veterinary clinics. Materials and methods: Two samples with cotton hissops were obtained in inert surfaces from 8 veterinary clinics. The presence of pathogenic bacteria was established by growth in agar media, identification of species was performed through colonies morphology and Gram stain and biochemistry identification with API20E and API50 CH/E system and antibiogram. Results: 95 isolates were characterized and within them 28 were pathogenic. The most prevalent were Pseudomonas aeruginosa, Proteus sp. and Staphylococcus sp. Conclusions: This is the first description of pathogenic microorganisms present in veterinary clinics in Antioquia that have potential for clinical consequences for personnel working at this veterinary centers.

Epidemiology and antibiotic resistance of methicillin-resistant Staphylococcus aureus in Jingzhou / 中华临床感染病杂志

Objective To investigate the epidemiology and antibiotic resistance of communityassociated and hospital-associated meticillin-resistant Staphylococcus aureus (CA-MRSA and HA-MRSA) in Jingzhou.Methods A total of 159 MRSA isolates were successively collected from patients in Jingzhou Central Hospital during January 2012 and December 2013.The minimum inhibitory concentrations of 16 antimicrobial agents against 159 MRSA isolates were detected.SCCmec types of the strains were detected by multiplex PCR,and the homology of the strains was analyzed using pulsed field gel electrophoresis (PFGE) and cluster analysis of antibiogram.WHONET 5.6 and SPSS 19.0 were used for data analysis.Results Among 159 MRSA strains,131 were hospital-associated,and 28 were community-associated,which accounted for 82.4％ and 17.6％,respectively.There were significant differences in the age of patients,ward distribution,specimen type,length of stay,length of anti-infection treatment,type of infection and underlying diseases between patients with CA-MRSA or HA-MRSA infections (x2 =19.103,31.372,59.756,71.703,54.153,59.756 and 54.232,all P ＜ 0.01).No vancomycin,linezolid,tigecyeline and nitrofurantoin resistant strains were found,but all strains were resistant to penicillin,cefoxitin and oxacillin.HA-MRSA had higher resistance rates to moxifloxacin,levofloxacin,rifampicin,ciprofloxacin and gentamicin than CA-MRSA (x2 =30.179,27.352,28.523,28.523 and 25.987,all P ＜ 0.01),but its resistance rates to erythromycin and clindamycin were lower (x2 =13.106 and 11.743,both P ＜ 0.01).Among 159 MRSA strains,12 (7.5％) were of SCCmec type Ⅱ,113 (71.1％) were of SCCmec type Ⅲ,26 (16.4％) were of SCCmec type Ⅳ,and 8 were of undifferentiated type.The predominant SCCmec types were type Ⅳ for CA-MRSA (26/28,92.9％) and type Ⅲ for HA-MRSA (113/131,86.3％),respectively.Six PFGE patters were found in 49 HA-MRSA isolates from ICU,and the predominant patters were A1 (24,49.0％),A2 (9,18.4％) and B (9,18.4％).Cluster analysis of antibiogram showed that three groups of HA-MRSA were of high correlations,and they were of PFGE patter A1,A2 and B,respectively.Conclusions HA-MRSA is the predominant MRSA in Jingzhou area,and it is different from CA-MRSA in the age of patients,ward distribution,type of infection and antibiotic resistance.Most HA-MRSA strains are of type SCCmec Ⅲ,and may cause epidemic outbreak in ICU.