Coagulase Test Research Articles

Three-Way Comparison of BBL CHROMagar MRSA II, MRSA Select , and Spectra MRSA for Detection of Methicillin-Resistant Staphylococcus aureus Isolates in Nasal Surveillance Cultures

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired and life-threatening infections. Active surveillance programs for MRSA utilize either molecular or culture-based methods. A prospective study was performed to compare the performance of selective and differential chromogenic media, BBL CHROMagar MRSA II (CMRSA II; BD Diagnostics, Sparks, MD), MRSASelect (Bio-Rad Laboratories, Redmond, WA), and Spectra MRSA (Remel, Lenexa, KS), for the detection of MRSA in nasal swab specimens. A total of 515 compliant remnant nasal swab specimens were sequentially used to inoculate BBL Trypticase soy agar with 5% sheep blood (TSA II) and each chromogenic medium. After 24 h of incubation, colony color reactions and morphology on chromogenic media were compared to suspicious colonies on nonselective TSA II. MRSA on TSA II was confirmed by Gram staining, a coagulase test, and a cefoxitin disk test. The overall prevalence of MRSA and methicillin-susceptible S. aureus (MSSA) on TSA II was 12.4% (64/515) and 9.7% (50/515), respectively. When each chromogenic medium was compared to the standard culture method, the sensitivity and specificity, respectively, were as follows: CMRSA II, 87.7% and 98.6%; MRSASelect, 89.0% and 93.4%; and Spectra MRSA, 83.6% and 92.1%. The positive predictive values were highest for CMRSA II (91.4%), followed by MRSASelect (69.1%) and Spectra MRSA (63.5%). False-positive results on chromogenic media were mainly due to color interpretation. The negative predictive values for all three media were greater than 97%. In conclusion, CMRSA II gave the best overall results for detecting MRSA from nasal specimens.

Comparison of the Staphylococcus QuickFISH BC Test with the Tube Coagulase Test Performed on Positive Blood Cultures for Evaluation and Application in a Clinical Routine Setting

Many studies demonstrate that delayed proper therapy in bloodstream infections caused by Staphylococcus aureus increases the mortality rate, emphasizing the need to shorten the turnaround time for positive blood cultures. Different techniques are currently available, from phenotypic methods to more complex tests such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), real-time PCR (RT-PCR), and fluorescence in situ hybridization using peptide nucleic acid probes (PNA FISH). This study evaluated the performance of the Staphylococcus QuickFISH BC test (QFT), a novel FISH methodology, compared with the direct tube coagulase test (DTCT) on blood cultures exhibiting Gram-positive cocci in clusters. A total of 173 blood cultures collected from 128 different patients were analyzed using the DTCT, evaluated after both 4 and 24 h, and the QFT. A total of 179 isolates were identified using the Vitek2 system. Thirty-five out of 35 Staphylococcus aureus were correctly identified by the QFT (sensitivity = 100%), with a specificity of 100% (no green fluorescence was detected for strains different from S. aureus). The DTCT was positive after 4 h for 28 out of the 35 samples (sensitivity = 80%) and after 24 h for 31 out of the 35 samples (sensitivity = 88.57%). Among the remaining 144 isolates, one was then identified as Corynebacterium striatum and two as Micrococcus luteus. QFT identified 139 out of the 141 coagulase-negative staphylococci (CoNS) (sensitivity = 98.58%), showing again a specificity of 100% (no fluorescent red signals were detected for strains different from CoNS). We also discuss also the implementation process of this methodology in our setting, with particular emphasis on the workflow and the cost-effectiveness.

The evaluation of staphylococci strains isolated from nasal and bone cultures in patients with chronic osteomyelitis

Objectives: In this study, it was aimed to determine the prevalence of nasal carriage of S. aureus in chronic osteomyelitis, assessed trends in methicillin resistance with time, and evaluated the bone and nasal cultures in staphylococcal chronic osteomyelitis. Materials and methods: Bone and nasal cultures were performed intra-operative and pre-operatively from 43 patients with chronic osteomyelitis. Inoculation was performed on 5% sheep blood and eosine-methylen-blue agar. The samples were incubated at 37°C for 24 hours. Catalase and coagulase tests were performed on Gram positive coccus strains. Antimicrobial susceptibilities of all S. aureus strains were evaluated by disc diffusion method according to CLSI for oxacillin and other antibiotics. Results: In this study pre-operative nasal cultures and intra-operative bone cultures obtained between May 2005 and September 2006 were evaluated retrospectively. Of the 43 nasal cultures, 31 (72%) yielded staphylococcal strain, of these 18 (58%) were S. aureus. Of the 18 S. aureus strains, 13 (72.2%) have methicilline resistance. On the other hand, of the 43 bone cultures, 29 (67.4%) yielded staphylococci strain, of these 23 (79.3%) were S. aureus. Of the 23 S. aureus strains, 52.1% have methicilline resistance. Overall the similarity rate of staphylococcal strains was 38% (11/29), while considering the status of strains resistant to antibiotics; this ratio was 24% (7/29). Conclusions: Nasal S. aureus carriage rate (58%) in patients with chronic osteomyelitis was higher than the community and the other patient groups. However, the surveillance cultures can give knowledge about the causative pathogen of 25% of the culture negative cases.

Skin flora: Differences between people affected by Albinism and those with normally pigmented skin in Northern Tanzania – cross sectional study

BackgroundSkin flora varies from one site of the body to another. Individual’s health, age and gender determine the type and the density of skin flora.MethodsA 1 cm2 of the skin on the sternum was rubbed with sterile cotton swab socked in 0.9% normal saline and plated on blood agar. This was cultured at 35°C. The bacteria were identified by culturing on MacConkey agar, coagulase test, catalase test and gram staining. Swabs were obtained from 66 individuals affected by albinism and 31 individuals with normal skin pigmentation. Those with normal skin were either relatives or staying with the individuals affected by albinism who were recruited for the study.ResultsThe mean age of the 97 recruited individuals was 30.6 (SD ± 14.9) years. The mean of the colony forming units was 1580.5 per cm2. Those affected by albinism had a significantly higher mean colony forming units (1680 CFU per cm2) as compared with 453.5 CFU per cm2 in those with normally pigmented skin (p = 0.023). The skin type and the severity of sun- damaged skin was significantly associated with a higher number of colony forming units (p = 0.038).ConclusionIndividuals affected by albinism have a higher number of colony forming units which is associated with sun- damaged skin.

Antibiotic-resistance Staphylococcus aureus isolated from cow’s milk in Hawassa area, South Ethiopia

Quarter milk samples from cows were examined to determine the prevalence ofStaphylococcus aureus (SA) and different antibiotic resistant pattern were determined in a cross-sectional study design. The aim of this study was to isolate Staphylococcus aureusfrom samples of cow’s milk obtained from Hawassa area and to determine their antibiotic susceptibility patterns. A total of 160 milk (CCP1 to CCP5) samples were collected and screened for the presence of S. aureus. Gram staining, oxidase, catalase, DNase, haemolysis and coagulase tests were employed for bacterial identification. All the samples were contaminated with S. aureus. A total of 78 S. aureus isolates were obtained during this study. The levels of contamination with S. aureus were higher in milk obtained from CCP1, CCP2, CCP3, CCP4 and CCP5 at Hawassa area farms (18.0, 25.6, 27.0, 21.8 and 7.7%) respectively. A large percentage of the S. aureus isolates (25.6 and 27.0%) were from CCP2 and CCP3. All strains were resistant to penicillin G (PG), ampicillin (AP), amoxicillin-clavulanic acid (AC), ciprofloxacin (CIP), erythromycin (E), Ceftriaxone (CRO), trimethoprime-salfamethoxazole (TMP-SMZ) oxacilin (Ox) and vancomycin (V), 67.9, 70.9, 30.9, 0, 32.1, 23.1, 7.7, 60.3 and 38.5% respectively. The proportion of isolates resistant to CIP, TMP-SMZ, CRO, AC, E and V were low compared to AP, PG and Ox. S. aureus is normally resident in humans; therefore, the S. aureuspresent in the cow’s milk may have resulted from transmission between the two species, emphasizing the need to improve sanitary conditions in the milking environment. Key words: Penicillin G (PG), ampicillin (AP), amoxicillin-clavulanic acid (AC), ciprofloxacin (CIP), erythromycin (E), ceftriaxone (CRO), trimethoprime-salfamethoxazole (TMP-SMZ), oxacilin (Ox), vancomycin (V).

Rapid tests: preliminar identification from blood culture

In the period 1 April to 30 June 2011, we compared the rapid test identification of 250 positive blood cultures with the identification by MALDI-TOF mass spectrometer (Bruker). After Gram staining and an important step in HB&L liquid culture (Alifax), rapid tests were performed according to the morphological characteristics of the sample. Pneumococcus urinary antigen test and tube coagulase test showed a concordance of 100%, the concordance rates for Pyr test and oxidase test were 91% and 89% respectively. Overall, the percentage of agreement of the rapid tests on 250 samples was found to be of 99.2%. The data obtained show that, even with their increased bacterial concentration due to the enrichment step in HB&L liquid culture, it is possible to obtain preliminary identification directly from positive blood culture with simple rapid tests.

First report of a left ventricular assist device infection caused by Staphylococcus schleiferi subspecies coagulans: a coagulase-positive organism

Staphylococcus schleiferi subspecies coagulans is often misclassified as S. aureus given the production of a pseudocoagulase turning the tube coagulase test positive. It is therefore infrequently reported in the literature. We describe the first case of S. schleiferi subspecies coagulans left ventricular assist device infection in a patient awaiting heart transplantation.

Changes in Antibiotic Susceptibility Pattern of Atypical Staphylococcus Aureus Strains Isolated from Cows of the same Herd in 2008-2010

Abstract The isolates of Staphylococcus aureus strains were examined phenotypically by cultural features, tube coagulase test and clumping factor (CF), and genotypically by conventional PCR. The strains had positive reaction in CF test, but were negative in tube coagulase test. The analysed strains from the same cows in each year expressed also nuc and coa genes. About 25% of the strains were examined by the disc diffusion method for their sensitivity to antibiotics. During three years, the strains were highly susceptible in vitro to amoxicillin with clavulanic acid, oxacillin, bacitracin, and cefoperazone (more than 90%), and highly resistant to tetracycline, neomycin, and streptomycin. Forty randomly chosen strains, and eight strains from the same cows in each year were analysed for minimal inhibitory concentration of penicillin G using microdilution method. An increasing resistance to the penicillin was noted. Moreover, eight strains, the same in each year, were also examined for β-lactamase production and methicillin resistance. No β-lactamase producers and no methicillin resistant strains were found using phenotypic and genotypic methods. In conclusion, it can be stated that antimicrobial susceptibility can change from one year to another.

New Technique use to differentiate between Pseudo and true coagulase Activity of Staphylococcus aureus isolated from Different infected Sites in Patients from Baghdad Hospitals

A total of 300 strains of Staphylococci isolated from various pathological sites of infection from different hospitals; these specimens derived from cases ofhuman infections were tested for staphylocoagulase activity.
 Test systems employing normal citrated rabbit plasma and the same substrate supplemented with inhibitors of thrombin and proteolytic enzymes (but notinfluencing the staphylocoagulase activity) were used for testing suspensions of bacteria and cell-free culture supernatants. A total of 200 strains clotted normal rabbit plasma; however addition of Trasylol and heparine resulted in positive results in 100 strains, whereas plasma supplemented with Trasylol and hirudin was coagulated definitely by only 70 strains.It is postulated that proteolytic enzymes of staphylococci interfere with staphylocoagulase-induced clotting and may simulate coagulase-positve activity of staphylococci.To avoid such false results, attest system for detection of sse shtaphylocoagulaould include proteolytic enzyme inhibitors The purpose of this investigation was to verify this hypothesis by testing a collection of staphylococci strains from different sources of infections against rabbit plasma in atypical coagulase test versus the same supplemented with specific inhibitors of proteases and thrombin depending on the sever sites of infections.

Multicenter Evaluation of the LightCycler MRSA Advanced Test, the Xpert MRSA Assay, and MRSASelect Directly Plated Culture with Simulated Workflow Comparison for the Detection of Methicillin-Resistant Staphylococcus aureus in Nasal Swabs

Rapid detection of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) followed by appropriate infection control procedures reduces MRSA infection and transmission. We compared the performance and workflow of two Food and Drug Administration-approved nucleic acid amplification assays, the LightCycler MRSA Advanced Test and the Xpert MRSA test, with those of directly plated culture (MRSASelect) using 1202 nasal swabs collected at three U.S. sites. The sensitivity of the LightCycler test (95.2%; 95% CI, 89.1% to 98.4%) and Xpert assay (99%; 95% CI, 94.8% to 100%) did not differ compared with that of culture; the specificity of the two assays was identical (95.5%; 95% CI, 94.1% to 96.7%) compared with culture. However, sequencing performed on 71 samples with discordant results among the three methods confirmed the presence of MRSA in 40% of samples that were positive by both molecular methods but negative by culture. Workflow analysis from all sites including batch runs revealed average hands-on sample preparation times of 1.40, 2.35, and 1.44 minutes per sample for the LightCycler, Xpert, and MRSASelect methods, respectively. Discrete event simulation analysis of workflow efficiencies revealed that the LightCycler test used less hands-on time for the assay when greater than eight batched samples were run. The high sensitivity and specificity, low hands-on time, and efficiency gains using batching capabilities make the LightCycler test suitable for rapid batch screening of MRSA colonization.

Evaluation of chromogenic meticillin-resistant Staphylococcus aureus media: sensitivity versus turnaround time

Chromogenic media offer the potential for improved detection of meticillin-resistant Staphylococcus aureus (MRSA). Incubation times in a clinical setting vary, generally between 16 and 48h. To investigate the effects of incubation time on the performance of commercial chromogenic MRSA media. We initially compared the early recovery of MRSA isolates from routine screening swabs following 16-23h to that after 22-24h of incubation using ChromID MRSA (bioMérieux). We also compared ChromID MRSA, ChromID MRSA V2 (bioMérieux), Brilliance MRSA 2 Agar (Oxoid) and Colorex MRSA (E&O Laboratories Ltd) as selective media for 6035 MRSA screening swabs. Only 303 of 623 (48.6%) MRSA isolates detected by this medium after 48h were recovered after 16-23h compared with 726 of 1018 (71.3%) isolates after 22-24h. Following implementation of the 22-24h incubation period, 50 (4.4%) isolates exhibiting a positive chromogenic reaction gave conflicting coagulase latex and DNase results. In 88% of these cases, DNase gave the correct result of non-MRSA. ChromID MRSA demonstrated the highest sensitivity overall at 93.2%, followed by Colorex MRSA Agar (87.1%), ChromID V2 (83.7%) and Brilliance Agar (78.2%). All media exhibited specificities of >99.7%. Early detection of MRSA using ChromID MRSA is best achieved after incubation for 22-24h. Latex agglutination coagulase tests alone should not be relied upon for identification of MRSA isolates from this medium. Although ChromID MRSA was deemed the superior medium in terms of MRSA recovery, the disadvantages of increased turnaround time (48 vs 24h) must be considered.

Research Article: Prevalence of MRSA on meat products in central Kentucky

Abstract. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from 10 (18.5%) of 54 meat samples collected in central Kentucky. Meat specimens were collected from six local markets in the central Kentucky region. MRSA found in meat samples may be a possible source for community-associated infections of MRSA. There were nine samples obtained from each location (18 pork, 18 beef, and 18 processed meats). The specimens were placed on ice for transport to the lab where they were individually processed using an aseptic technique. Meat samples were streaked for isolation on mannitol salt agar plates (MSA) and placed in 7% salt enrichment broth upon arrival in the laboratory. MSA isolates that fermented mannitol were tested for the presence of Staphylococcus aureus (S. aureus) with the coagulase and d-trehalose fermentation test. S. aureus isolates were placed on the oxacillin agar screen test (Mueller Hinton Agar with 6 μg/mL oxacillin and 4 % NaCl) to determine if MRSA was present. The positive spe...

Identification and determination of coagulase-negative Staphylococci species and antimicrobial susceptibility pattern of isolates from clinical specimens

Full Length Research Paper Identification and determination of coagulase-negative Staphylococci species and antimicrobial susceptibility pattern of isolates from clinical specimens Ahmad Farajzadeh Sheikh* and Manijeh Mehdinejad Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences (AJUMS), Ahvaz, Iran. *Corresponding author. E-mail: farajzadehah@Gmail.com. Tel: +98-611- 3738154. Fax: +98-611-3332036. Accepted 19 September, 2011 Abstract Coagulase negative Staphylococci (CoNS) are the important agents in nosocomial infection. Recently, resistant of CoNS against antimicrobial agents is increasing. The aim of this study is determination of species of CoNS, and antimicrobial susceptibility pattern of species obtained from clinical specimens. Clinical specimens from different organism were collected. Laboratory tests included: culture, Gram stain, coagulase test, biochemistry tests, and antimicrobial susceptibility pattern were performed by standard methods. 201 Staphylococci were isolated from varying infected organ, of which 134(66.7%) were identified as proven CoNS that distributed among 16 species. The majority of species of CoNS was Staphylococcus epidermidis (19.4%) and the lowestStaphylococcus auricularis ( ,(0.74Staphylococcus caprae (0.74%) and Staphylococcus intermedius (0.74%). Also majority of CoNS related to organ was obtained from urine specimens (51.5%). The antimicrobial susceptibility patterns showed that the most resistant of the CoNS belonged to oxaciline (94.02%) and least resistant belong to vancomycine (20.89%). Among of the CoNS species, S. epidermidis (96.15%) have had higher resistant to oxacillin. S. epidermidis had the highest frequency among the CoNS which were isolated from clinical specimens, and majority of CoNS were isolated from urine specimens, the higher resistant of CoNS belonged to oxaciline and the lowest to vancomycine. Key words: Coagulase negative Staphylococci (CoNS), antimicrobial susceptibility pattern, clinical specimens.

Isolation and Identification of Methicillin-Resistant Staphylococcus aureus from Keys of College Students Using Different Detection Methods

Aims: In this study, the methicillin-resistant Staphylococcus aureus (MRSA) were isolated and identified by using biochemical tests, antibiogram and polymerase chain reaction (PCR) to explore the circulation of MRSA among college students. Study design: Cross-sectional study. Place and Duration of Study: Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia Research Article British Biotechnology Journal, 2(1): 13-25, 2012 14 between June 2010 and December 2010. Methodology: A total of 100 samples were collected from keys of college students. There were 39 isolates (39 %) Gram-positive cocci and Catalase positive. 29 (74.36%) were glucose oxidation and fermentation positive. From the 39 isolates, 16 (43.24%) were shown Mannitol Salt Agar (MSA) tests positive. The deoxyribonuclease (DNase) tests and tube coagulase tests with human and rabbit plasma were carried out to improve the efficiency of the MSA test. Results: 7 (43.75%) DNase positive and 2 (12.5%) tube coagulase positive. Both human and rabbit plasma showed similar sensitivity for the tube coagulase tests in this study. However, both isolates with tube coagulase positive were confirmed as S. aureus but not resistant to oxacillin, methicillin, erythromycin and cefoxitin. 2 (66.67%) of 3 (18.75%) isolates which is tube coagulase negative were resistant to erythromycin and 1 (33.33%) of them was resistant to methicillin. Rare strains of S. aureus can be coagulase negative. PCR assay was used. 1 (33.33%) of the coagulase negative isolate resistant to erythromycin was found to have nuc gene, mecA gene, ermC gene, msrA gene, linA gene, and femA gene. The isolate was confirmed as MRSA. Conclusion: In conclusion, PCR technique is more sensitive and reliable than tube coagulase test or antibiogram for the detection of MRSA. And keys were shown to be an important source of MRSA and other bacteria circulation in the community.

Isolation and Identification of Bacteria in Retailed Smoked Fish, Within Bauchi Metropolis

smoked fish samples were bought from retailers within Bauchi metropolis, from three different locations, for the isolation and identification of bacteria. 16 (53%) of the samples were catfish (Clarias specie) which were dried in the sun before smoking (DSF) and the other 14 (47%) samples were frozen mackerel which had been thawed before smoking (ISF). The dried smoked fish (DSF) samples showed the mean bacteria count of 2.4 x 10 4 cfu/g which was observed to be less than the mean count in iced smoked fish (ISF) samples which is 2.8 x 10 4 cfu/g. The three different locations which includes: Yelwa market, Wunti market and Muda Lawan market showed different aerobic bacteria count. A serial dilution of up to 10 -3 in peptone water was carried out. 1ml of each sample was cultured by pour plating on Nutrient agar and McConkey agar and incubated at 37 o C for 24 hours. The isolates identified were Staphylococcus aureus, Salmonella typhi, Proteus mirabilis, Klebsiella spp, Streptococcus spp and Bacillus cereus. The biochemical tests carried out for the identification for these isolates includes: Catalase test, Coagulase test, Urease test, triple sugar ion test, citrate utilization test and indole formation test. Key Word: smoked fish, bacteria, identification, serial dilution

Antibiotic-resistance Staphylococcus aureus isolated from cow's milk in the Hawassa area, South Ethiopia.

BackgroundQuarter milk samples from cows were examined to determine the prevalence of Staphylococcus aureus (SA) and different antibiotic resistant pattern were determined in a cross-sectional study design.ObjectiveThe objective of this study was to isolate Staphylococcus aureus from samples of cow’s milk obtained from Hawassa area and to determine their antibiotic susceptibility patterns.MethodA total of 160 milk (CCP1-CCP5) samples were collected and screened for the presence of S. aureus. Gram staining, oxidase, catalase, DNase, haemolysis and coagulase tests were employed for bacterial identification.ResultsAll the samples were contaminated with S. aureus. A total of 78 S. aureus isolates were obtained during this study. The levels of contamination with S. aureus were higher in milk obtained from CCP1, CCP2, CCP3, CCP4 and CCP5 at Hawassa area farms (18.0%, 25.6%, 27.0%, 21.8% and 7.7%) respectively. A large percentage of the S. aureus isolates (25.6% and 27.0%) were from CCP2 and CCP3. All strains were resistant to Penicillin G (PG) (10 μg), Ampicillin (AP) (10 μg), Amoxicillin-Clavulanic acid (AC) (30 μg), Ciprofloxacin (CIP) (5 μg), Erythromycin (E) (15 μg), Ceftriaxone (CRO) (30 μg), Trimethoprime-Sulfamethoxazole (TMP-SMZ) (25 μg) Oxacillin (Ox) (1 μg) and Vancomycin (V) (30 μg), 67.9%, 70.9%, 30.9%, 0%, 32.1%, 23.1%, 7.7%, 60.3% and 38.5% respectively.ConclusionThe proportion of isolates resistant to CIP, TMP-SMZ, CRO, AC, E and V were low compared to AP, PG and Ox. S. aureus is normally resident in humans; therefore, the S. aureus present in the cow’s milk may have resulted from transmission between the two species, emphasizing the need to improve sanitary conditions in the milking environment.

Investigation of susceptibility of Staphylococcus species to some antibacterial drugs by disk diffusion and broth microdilution

The objective of this work was to identify isolated Staphylococcus species and to investigate their sensitivity to some antibacterial drugs. The material used for these investigations were Staphylococcus isolates originating from milk samples. A total of 25 strains of Staphylococcus isolates were examined, including 24 from milk samples from cows with mastitis, and one strain was isolated from a milk sample from a cow following treatment for mastitis. For primary identification, catalase and oxidase tests were used, as well as the free coagulase test. Following the preliminary tests, the isolated strains were identified using commercial systems ID32 STAPH (bioM?rieux, France) and the BBL Crystal Gram-Positive ID Kit (Becton Dickinson, USA) according to the enclosed instructions. The Staphylococcus isolates were examined for sensitivity to the following: oxacillin, penicillin, cefoxitin, gentamicin, erythromycin, chloramphenicol, tetracycline, ciprofloxacin, sulfametoxazol/trimetoprim, and vacomycin using the disk diffusion method and the broth microdilution method as recommended by the Clinical and Laboratory Strandards Institute - CLSI(2003), and the results were interpreted according to CLSI recommendations from 2008 and 2010. Antibiogram disks manufactured by Becton Dickinson (USA) were used, and the broth microdilution method was applied using pure antibiotic substances from different manufacturers: erythromycin, chloramphenicol, cefoxitin, gentamicin, oxacillin, tetracycline (Sigma Aldrich, USA), sulfametoxazol (Fluka, USA), penicillin (Calbiochem, Germany), vancomycin (Abbott laboratories, USA), ciprofloxacin and trimetoprim (Zdravlje A.D., Serbia). All 25 strains were catalase positive and oxidase negative. Of the 25 strains, 19 were coagulase positive and 6 were coagulase negative.With the implementation of the disk diffusion method on 19 strains of S. aureus, 17 were established to be resistant to penicillin (89.5%), and 2 strains to gentamicin (10.5%). The investigation of 3 strains of S. xylosus using the disk diffusion method showed that one strain was resistant to tetracycline (33.3%) and to oxacillin (33.3%), while another strain was found to be resistant to penicillin (33.3%). The third strain of S. xylosus was sensitive to all the examined antibiotics. Two strains of S. simulans and one strain of S. haemolyticus were not found to be resistant to any of the examined antibiotics using the disk diffusion method. The implementation of the broth microdilution method yielded in 13 strains of S. aureus resistance to penicillin (68.4%) with MIC values from 0.5 to 4 ?g/m, in 2 strains to gentamicin (10.5%) with MIC values of 32 ?g/ml, and intermediary sensitivity to chloramphenicol was established in 9 strains of S. aureus (47.4%) with MIC values of 16 ?g/ml and to vancomycin in 1 strain of S. aureus (5.3%) with MIC values of 4 ?g/ml.

Detection of mecA genes of Methicillin-Resistant Staphylococcus aureus by Polymerase Chain Reaction

Background: Methicillin-Resistant Staphylococcus aureus (MRSA) infections have become a global health problem particularly in hospital setup causing simple skin infections to life-threatening infections. In many developing countries, including India, the situation appears gloomy due to inadequate or poor implementation of policy on infection control, lack of political will, inadequate resources including shortage of skilled manpower, poor motivation of health care workers and researchers. Objective: The present study describes a rapid and accurate PCR for detection of clinically relevant antibiotic resistance gene of Staphylococcus aureus. Materials and Methods: A total of 586 Staphylococcus positive clinical samples were collected under aseptic precautions from patients attending various departments in a tertiary care hospital in south India. Staphylococcus aureus isolates were identified based on cultural characteristics, biochemical reactions and positive tube coagulase test. Methicillin resistance was determined by Kirby-Bauer’s disc diffusion method. The PCR was used for mecA gene detection from MRSA strains. Results: Of the total 586 Staphylococcal aureus isolated, 236 (40.2%) strains were MRSA. Thirty-five MSRA strains were randomly selected for PCR assay. Thirty three MRSA strains (94%) were mecA gene positive and two MRSA strains were mecA negative visualised on 2% agarose gel electrophoresis. Conclusion: The PCR assay was found to be rapid and accurate procedure for the detection of MRSA strains as compared to the conventional methods since the reporting time is less and can help efficiently in infection management.

Detection of resistance to linezolid in Staphylococcus aureus infecting orthopedic patients

In today's medical scenario, the human race is battling the most intelligent enemy who has unending alternatives to combat with the potent elements they have produced against it. To study the resistance to linezolid among Staphylococcus aureus isolated from pus samples of orthopedic patients. Pus samples were collected from dirty wounds of orthopedic patients undergoing long antimicrobial treatment programs. The sampling period was from July 2010 to June 2011. The samples were collected from different orthopedic hospitals of Nagpur (central India) representing a mixed sample of patients. One hundred pus samples were screened for S. aureus, by growth on mannitol salt agar (MSA), Baird-Parker agar (BPA), deoxyribonuclease test, tube coagulase test, and HiStaph latex agglutination test. Fifty-one S. aureus isolates were obtained which were further subjected to antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method (DDM). Minimal inhibitory concentrations (MICs) were determined by an automated system, the VITEK 2 system. Also, Ezy MIC strip method was carried out in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Twelve linezolid-resistant S. aureus (LRSA) isolates were recovered from 51 S. aureus cultures tested for susceptibility to linezolid using the DDM, VITEK 2 system, and Ezy MIC strip method. The emergence of resistance suggests nosocomial spread and abuse of antibiotic.

Identification and Characterization of Staphylococcus Isolates in Fes- Meknes Region in Morocco

Staphylococci are among the most commonly recovered bacteria in the clinical microbiology laboratories. According to the coagulase test, staphylococci are categorized as S. aureus and coagulase negative staphylococci (CoNS). Although S. aureus is more virulent, CoNS may also cause infections, some of which may be lifethreatening. Raising staphylococci multi-drogue resistance has complicated therapeutic protocols especially for S. aureus resistant to meticillin (SARM). In our study we characterized by phenotypic and molecular data, a group of staphylococci collected from hospital laboratories. Comparison between standard laboratories procedures in routine identification and molecular methods showed a good correlation of both. Multiplex-PCR revealed that all species specific 16S RNA positive were coagulase positive and identified to be S. aureus. Besides, all mecA positive isolates were cefoxitin resistant. The prevalence of SARM was found 11.76% while meticillin resistant coagulase negative staphylococcus (MRCoNS) was 84.61%. Although the analyzed staphylococcal isolates sample is small, our study revealed a relatively low prevalence of SARM in this region of Morocco compared to others region of the world. The very high prevalence of MRCoNS isolates is alarming and demonstrating that CoNS are becoming the main source for dissemination of mecA gene.