Detection of methicillin resistant staphylococcus aureus with reduced susceptibility to vancomycin

Background: As there is no molecular-based assays available for the detection of hVISA and VISA. However, increasing amounts of data support a number of methods for the screening and confirmation of heterogeneous vancomycin intermediate S. aureus [hVISA] and vancomycin intermediate S. aureus [VISA] infection. The vancomycin MIC result alone is unable to accurately distinguish hVISA from VSSA isolates, and the use of MIC testing alone will fail to detect h VISA strains that are relatively common among isolates of Staphylococcus aureus [S. aureus] with broth MICs of 2g per ml. of Staphlococcus aureus [S. aureus] with broth MICs of 2 g per ml

Objective: The aim of the present work was to detect the efficacy of phenotypic and automated methods for detection of MRSA with reduced susceptibility to vancomycin. It aimed also, to determine the best MIC concentration in vancomycin screening agar for detection of VISA among MRSA isolates

Methods: one hundred MRSA isolated were obtained from 100 patients from different departments of Ain Shams University Hospitals during the period from October 2015 to the end of April 2016. They were isolated from different clinical specimens; sputum, wound swabs, blood, pus, urine, and body fluid that were referred to central microbiology laboratory for routine culture and sensitivity. Detection of S. aureus with reduced susceptibility to vancomycin was done by vancomycin screening agar with different concentrations 2,4,6 ug/ml with and without casein, MIC broth microdilution method for vancomycin according to CLSI

Results: Out of 100 MRSA isolates, vancomycin screening agar 2 ug/ml with casein showed highest detection rate for VISA isolates [48%] among other screening agars. Vancomycin screening agar 6 ug/ml without casein gave the lowest detection rate [29%]. So, adding casein to vancomycin screening agar did not increase detection of VISA in any of vancomycin screening agar except for that with 2 ug/ml vancomycin. Vancomycin screening agar 2 ug/ml with casein gave the best sensitivity among all vancomycin screening agar tested. VITEK 2 system failed to detect any isolates with reduced susceptivility to vancomycin. They were sensitive to linezolid [100%] followed by tigecyclin [99%] then Quinupristin-dalfopristin [91%]. However, most of the isolates were resistant to tetracycline [85%] followed by gentamicin [80%] then ciprofloxacin [63%]

Conclusion: BHI agar with 2 ug/ml vancomycin and 16 g/l casein is a reliable, easy to perform, and inexpensive method to screen large number of S. aureus isolates for detection of reduced susceptibility to vancomycin on a daily basis. Applying quadruplicate technique in vancomycin screening agar may increase the yield for detection of VISA isolates. Although vancomycin screening agar 6 ug/ml is recommended by CLSI as a screening method for detection of VISA, yet it did not perform well and underestimated VISA isolates. VITEK 2 system is not an appropriate method for detection of S. aureus with reduced susceptibility to vancomycin [VISA]. MRSA isolates with reduced susceptibility to vancomycin can be treated effectively with Linezolid

Rapid identification and antimicrobial susceptibility profiling of , anaerobic bacteria in clinical specimens

Objective: The aim of the current study was to evaluate the ability of API 20A, and Microscan Rapid-Anaerobe identification system to identify a spectrum of clinically significant anaerobic isolates against the gold standard conventional method. Also to determine the antimicrobial susceptibility of anaerobic isolates using different methods. Materials and Methods: Anaerobes were isolated from the different clinical specimens and all isolates were initially identified by conventional tests. Identification of isolates were made also by using the API 20A and Microscan systems. Antimicrobial susceptibility of all isolates were determined by disc diffusion and broth-disk method and compared to MIC determined by broth dilution method. Results: A total of 51 isolates were recovered from clinical specimens. API 20A and Microscan correctly identified 70.6% and 82.4% of strains to species level respectively. Eight strains were misidentified by API 20A and 9 were misidentified by Microscan. E. fragilis group isolates were the most encountered clinically significant isolates among the gram-negative anaerobes. Penicillin and ampicillin had poor activity against B. fragilis group, Prevotella spp. Eubacterium spp. and Veillonella spp. Members of the B. fragilis group were more resistant to cefoxitin, than other anaerobes [66.6%]. Resistance to clindamycin varied among the species range from 11.1% to 50%. Chloramphenicol was effective against all isolates. Fusobacterium spp. were highly susceptible to penicillin and 33.3 % of Fusobacterium isolates were resistant iu metronidazole. Clostridium perfhngens isolates were susceptible to all agents tested. Clostridium species other than C. perfringens were more resistant than C. perfringens, with 75% of the isolates resistant to penicillin, 12.5% resistant to clindamycin, and 18.7% resistant to metronidazole. Disk diffusion method has correlated well with MIC values but give poor correlation most tested C. perfringens. The overall correlation of the broth-disk results with MIC values was 97.6% in all tests. Conclusions: It was concluded that Microscan RAID was easier to perform and interpret and has the potential to provide rapid identification of anaerobes with an automated reader but more expensive than API, Both system give reliable rapid identification of anaerobes. Our study indicate that there continue to be changes in susceptibility of anaerobes over time and the antimicrobial resistance patterns should be monitored regularly in order to guide empirical therapy. Attention should be paid to standardize broth-disk method as an easy, rapid and most practical to be applicable to routine use for clinical laboratories?

Phenotypic characterization and ERIC-PCR Typing of MDR acinetobacter species in Egypt

Introduction: identification and typing of microorganisms are vitally important in efforts to monitor the spread of virulent or epidemic pathogens. Acinetobacter infection has been increased in hospitals and communities worldwide, and its resistance to virtually all antimicrobial agents has rapidly increased in recent years. Owing to that the aim of the present study was to characterize Acinitobacter species and evaluate their antimicrobial susceptibility profiles. Also, our study aimed to determine the value of using ERIC-PCR for speciation of multidrug resistance [MDR] Acinitobacter

Materials and methods: seventy six Acinitobacter species were isolated and identified in the study. Both automated and conventional methods were used to identify Acinitobacter species and to detect the antimicrobial susceptibility pattern of the isolates. These isolates were then analyzed genotypically via enterobacterial repetitive consensus [ERIC]-PCR

Results: acinitobacter baumannii was the predominant Acinitobacter species. In our study 77.6% of Acinitobacter isolates were MDR. 8.5% of the MDR isolates were resistant to all tested antimicrobial agents. The prevalence of resistance to ceftriaxon, cefotaxime, pipracillin, ticarcilline/clveolinic acid and aztreonam were high [85.6, 77.5, 86.9, 78.9 and 93.3%, respectively] in the present study. We detected a significant amount [52.6%, 40 of 76] of imipenem-resistant isolates. This study determined that good discrimination between groups of MDR Acinetobacter species. Was achieved with ERIC -PCR

Conclusion: ERIC-PCR was found to be a rapid, simple, and discriminatory method in investigation of MDR Acinitobacter and seems to be well suited for epidemiological studies of Acinitobacter species

Isolation and antimicrobial susceptibility of aerobic and anaerobic bacteria of periodontitis in Egyptian diabetic patients

Background: diabetes has been associated with periodontal disease for many years. Diabetes is recognized as an important risk factor for more severe and progressive periodontitis, infection or lesions resulting in the destruction of tissues and supporting bone that form the attachment around the tooth

Aim: the aim of this study was to detect and identify bacteria of periodontal infection among diabetic patients, L% determine the antimicrobial susceptibility pattern of isolated aerobic and anaerobic bacteria to commonly used antibacterial agents and to evaluate the antibacterial activity of one natural products such as meswak chewing sticks [Salvadora persica] on periodontal isolates

Methods: the study includes 41 diabetic patients suffering from periodontitis. Specimens were examined for aerobic and anaerobic bacterial infections. Isolated bacteria were identified by conventional biochemical tests. Antimicrobial susceptibility was tested for all isolates by agar plate disc diffusion method. Antibacterial activity o f meswak was tested by both cup plate method and micro dilution assay

Result: result revealed that the main etiological agent of periodontitis was alpha-haemolytic streptococci, coagulase negative staphylococci [CNS], Klebseilla spp., Prevotella melaninogenica and Fusobactrium nucleatum. The aqueous extract of S. persica shows good antimicrobial activity using microdilution assay and has week activity by cups plate method. The resistances of all periodontal pathogen were relatively low against Amoxicillin /Clavulanic acid, Piperacillin/Tazobactam, Ertapenem and Chloramephenicol

Conclusion: periodontitis were often polymicrobial and could be associated with potentially pathogenic organisms. Antimicrobial agents such as amoxicillin-clavulanate or piperacillin-tazobactam and ertapenem could be used for empirical treatment of mixed infections particularly those associated with anaerobic organisms

invivo and invitro evaluation of the effectiveness of different denture cleansing methods on microorganisms and surface roughness of acrylic resin

Objectives: the aim of this study was to evaluate the effect of different denture cleansing methods on microorganisms and surface roughness of acrylic resin both invivo and invitro

Material and methods: one hundred and eleven discs were used. Thirty six discs were chosen for the roughness evaluation and a further seventy five for the microbiological test. For the invivo evaluation, thirty six patients who were wearing their dentures for more than one year were selected. Three types of cleansers were evaluated; electric toothbrush as a mechanical method, effervescent tablets as a chemical immersion and propolis as a natural immersion, and water was used as control. In vitro cleansing of discs simulated one year of cleansing. Surface roughness was measured with profilometer, invivo and invitro microorganisms count were evaluated before and after cleansing. Correlation between roughness and microorganisms count was done

Results: the three types of cleansers showed significant effect on roughness and on microorganisms invivo and invitro. There was highly significant difference after cleansing between the 4 groups regarding roughness [F= 41.51, P= 0.000], invivo bacterial count [F= 19.487, P= 0.000] and fungal count [F= 6.666, P= 0.001]

Conclusion: the effect of propolis and effervescent tablets on microorganisms was comparable and they were more effective than the brush method. However, Propolis was found with a powerful antimicrobial effect against most oral microorganisms, and can be used on prescription as a denture soak with equivalent or higher effect as a cleanser especially with its advantage as a promising natural product