Coagulase Test Research Articles

Isolation and Characterization of Microbial Contamination from Computer Accessories used in Different Department of Hazara University and Diagnostic Laboratories of District Mansehra, Pakistan

samples were collected from computer accessories used in Hazara University and different diagnostic laboratories of Mansehra, examined for the total bacterial count and maximum growths were observed. Samples were analyzed for further identification of micro-organisms such as E.coli, Klebsiella, Staph. aureus and Staph. epidermidis. These organisms were detected in the percentage of 46.66 of E. coli, 20% of Klebsiella, 16.66% of S. aureus & 16.66% of S. Epidermidis and identified on selective media, i.e. EMB agar and Mannitol salt agar. Furthermore, biochemical tests, including IMVIC Test, Catalase Test and Coagulase Tests were performed to confirm the presence of micro-organisms and their susceptibility also checked against different standard antibiotics and their zone of inhibitions were measured and noticed. E.coli showed maximum resistance of 97.36% against Erythromycin, Klebsiella showed against Amoxil + Clavolunic acid about 83.83%, Staph aureus showed against Erythromycin about 64.64% and Staph. epidermidis resistance was 90.9% against Erythromycin and Gentamycin. E.coli and Klebsiella showed maximum sensitivity for Meropenem 67.22% and 72.72% respectively while Staph. aureus and Staph. epidermidis maximum sensitivity for Vancomycin about 82.82% and 72.72% respectively. These results indicate that the computer accessories might act as environmental vehicles for the transmission of potentially pathogenic bacteria in our surroundings and also indicate the need for increasing awareness among computer users on cleaning of such surfaces or disinfection and adequate hand-washing hygiene.

Detection of Subclinical Mastitis in Dairy Cows using California Mastitis Test and Udder Pathogen

Subclinical mastitis is an infection of the udder devoid of clinical symptoms, bacteria are one of the causes behind this disease. In the present study, we investigated subclinical mastitis in dairy cows using the California mastitis test (CMT) and udder pathogens from KUNAK (Kawasan Usaha Peternak Sapi Perah) Cibungbulang, Bogor, West Java, Indonesia. We randomly collected 102 milk samples from dairy farms in different stalls. We found that 87 out of the 102 (86 %) milk samples were positive for CMT test with level+1, level+2, and level+3 were 22 %, 45 %, and 33 % respectively. We also identified three different major bacterial groups: staphylococcus, streptococcus, and enterobacteria based on gram staining, oxidase test, and coagulase test. It can be concluded that the case of bovine subclinical mastitis in Kunak Bogor was very high and caused by various bacteria which infected cows.

English

A swab of mobile phone and hands of health care workers (HCWs) were examined to determine the prevalence of Staphylococcus aureus (SA), different antibiotic resistant pattern were determined in a cross-sectional study design. The objective of this study was to isolate S. aureus from samples of mobile phone and hands of HCWs from Hawassa Referral Hospital and to determine their antibiotic resistant patterns. A cross-sectional study design was carried on 152 mobile phones and hands of HCWs from different rooms of Hawassa Referral Hospital and screened for the presence of S. aureus. Gram staining, oxidase, catalase, DNase, haemolysis and coagulase tests were employed for bacterial identification. 97.4% of the samples were contaminated with different microorganisms. However, the contamination level of S. aureus in mobile phone and hands of HCW’s were 53.9 and 55.5%, respectively. A total of 82 S. aureus isolates from mobile phone and 84 S. aureus were obtained from hands of HCWs during this study. The levels of contamination with S. aureus were slightly higher in hands of HCWs. About 65.9 and 47.6% strains were resistant to Ampicillin (AP) (10 μg) and Penicillin G (PG) (10 μg), respectively. About 26.8, 31.7, 15.9, 40.2, 26.6, 22.0, 14.6, 40.2 and 31.7% strains were resistant to Amoxicillin (Ax) (30 μg), Ciprofloxacin (CIP) (5 μg), Ceftriaxone (CRO) (30 μg), Oxacillin (Ox) (1 μg), Chloramphenicol (CAF) (10 μg), Doxycycline (DOX) (30 μg), Gentamycin (10 μg), Vancomycin (V) (30 μg) and Tetracycline TTC (30 μg), respectively. The resistant level of S. aureus to CIP, CRO, CAF, DOX and Ax were low as compared to AP, PG, V and Ox. S. aureus is normally resident in different habitat; therefore, the S. aureus present in the mobile phone and hands of HCW’s may have resulted from contamination of hands of HCWs, showing the need to improve personal hygiene conditions in the hospital, specially OR and ICU. The training of healthcare workers on strict infection control procedure, hand hygiene, mobile phone cleaning habit and environmental disinfection are standards to control pathogen transmission. Key words: Antibiotics, S. aureus, mobile phone, cell phone, health care workers (HCWs).

Prevalence of Methicillin-resistant Staphylococci Isolates from Horses and Horse-related Personnel in Korea

Methicillin-resistant staphylococci (MRS) are emerging as important pathogens in humans and animals worldwide. The aim of this study was to investigate the prevalence of MRS in the racehorse population and in horserelated personnel in Korea. A total of 195 horses and 18 humans (eight veterinarians, three veterinary hospital staff, and seven horse-handlers) from racehorse farms in Korea were included in the study. The samples were collected from nasal cavities using bacterial transport medium and were cultivated on tryptic soy agar with 5% sheep blood for 3 days at 37oC to confirm the presence of Staphylococcus spp. Presumptive Staphylococcus spp. isolates were identified by 16S ribosomal RNA gene analysis. The coagulase test and oxacillin susceptibility tests were performed using the tube dilution and disk diffusion methods, respectively. The presence of the mecA gene was determined using a polymerase chain reaction assay. Of the 195 horses, 29 (15.6%) yielded 29 MRS isolates. Twelve (66.7%) of the 18 horse-related personnel yielded 12 MRS isolates. All of the MRS isolates from horses or horse-related personnel were identified as methicillin-resistant coagulase-negative staphylococci (MRCNS). The result of this study suggest that the prevalence of MRS increased with the duration of antibiotic use (p = 0.002). This study also provides evidence for the zoonotic transmission of MRCNS between horses and humans, although further investigations are needed.

Diversity of healthcare-associated MRSA genotypes in Kuwait hospitals

MRSA strains A total of 205 nonrepeat MRSA isolates were obtained from patients in 13 Public hospitals in Kuwait between 1 January and 31 December 2010. Isolates were obtained from skin and soft tissues (N=78), Nose (N=56), Respiratory tract (N=27), Groin (N=11), Blood (N=10), Axilla (N=6), Vaginal swab (N=5) and miscellaneous samples (N=12). Isolation and identification of isolates were based on standard bacteriological protocols, Gram stain, positive catalase, Dnase and tube coagulase tests.

Antimicrobial susceptibility pattern of nasal Staphylococcus aureus among Dessie Referral Hospital health care workers, Dessie, Northeast Ethiopia

Staphylococcus aureus is a major pathogen in skin and soft tissue infections. Methicillin-resistant S. aureus (MRSA) is prevalent in most of the countries in which it is sought. MRSA is one of the important pathogens implicated in hospital-acquired infections. The main objectives of this study were to determine the antimicrobial susceptibility pattern of S. aureus isolates, the prevalence of MRSA, and the nasal carriage rate in healthy hospital staff members. A total of 118 health care workers (HCWs) were enrolled using a cross-sectional study design. Nasal swabs were collected and cultured on mannitol salt agar (MSA). The slide coagulase test was performed. Susceptibility testing was carried out on Mueller-Hinton agar using the modified Kirby-Bauer disk diffusion method with 10 antibiotics. Of the 118 HCWs, 34 had S. aureus and 15 had MRSA, with overall positivity rates of 28.8% and 12.7%, respectively. None of the S. aureus isolates were sensitive to penicillin. MRSA isolates were resistant to commonly available antibiotics. Only two (13.3%) of the nasal isolates were vancomycin-resistant. A high rate of nasal carriage and multidrug-resistant S. aureus was found in this study, indicating the need for standard infection control to prevent transmission in our health care setting.

Diversity of healthcare-associated MRSA genotypes in Kuwait hospitals

MRSA strains A total of 205 nonrepeat MRSA isolates were obtained from patients in 13 Public hospitals in Kuwait between 1 January and 31 December 2010. Isolates were obtained from skin and soft tissues (N=78), Nose (N=56), Respiratory tract (N=27), Groin (N=11), Blood (N=10), Axilla (N=6), Vaginal swab (N=5) and miscellaneous samples (N=12). Isolation and identification of isolates were based on standard bacteriological protocols, Gram stain, positive catalase, Dnase and tube coagulase tests.

Antibacterial Activity of New Oxazolidin-2-One Analogues in Methicillin-Resistant Staphylococcus aureus Strains

Staphylococcus aureus is one of the most common causes of nosocomial infections. The purpose of this study was the synthesis and in vitro evaluation of antimicrobial activity of 10 new 3-oxazolidin-2-one analogues on 12 methicillin resistant S. aureus (MRSA) clinical isolates. S. aureus confirmation was achieved via catalase and coagulase test. Molecular characterization of MRSA was performed by amplification of the mecA gene. Antimicrobial susceptibility was evaluated via the Kirby-Bauer disc diffusion susceptibility test protocol, using commonly applied antibiotics and the oxazolidinone analogues. Only (R)-5-((S)-1-dibenzylaminoethyl)-1,3-oxazolidin-2-one (7a) exhibited antibacterial activity at 6.6 μg. These results, allow us to infer that molecules such as 7a can be potentially used to treat infections caused by MRSA strains.

Molecular Characterization of Methicillin-Susceptible And Methicillin- Resistant Staphylococcus aureus in Food Handlers in Bosnia and Herzegovina

Objectives: To determine the prevalence and genetic background of methicillin-sensitive (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) obtained from healthy food handlers admitted to the Cantonal Public Health Institute of Zenica, Bosnia and Herzegovina, during 2007-2009. Methods: S. aureus were isolated and identified using standard microbiological methods including coagulase and catalase tests. Antibiotic susceptibility testing by disc diffusion method was performed according to the CLSI guidelines. Methicillin resistance was confirmed by the presence of the mecA gene by PCR. The genetic characterization was performed using spa-typing and BURP algorithm. Results: A total of 189 non-duplicated S. aureus isolates were collected from 13 690 nasal swabs (1.4%), of which three were MRSA (1.6%). Among 173 MSSA analyzed, 66 spa types were clustered into nine spa-CCs, four no founders, and singletons. The MSSA spa-CC015 associated with MLST CC45 was predominant, having 41 (24%) strains. All three MRSA were associated with MLST 152 (spa-CC 355/595) which was not found in MSSA isolates. MRSA-related background had 60% MSSA isolates. There were 127 (71%) MSSA and one MRSA sensitive to all antibiotic tested (the beta-lactam compounds excepted); multi-drug resistance was found in 13 (7.3%) of MSSA. Conclusion: Very low prevalence of S. aureus, as well as MRSA was noted. MSSA were more heterogeneous than MRSA. Although the number of MSSA with a genetic background common to MRSA clones was high, the prevalence of MRSA was low, and MLST CC152 of MRSA was not found among MSSA isolates suggesting that MRSA did not arise from predominant MSSA clones.

The Detection of Encoding Gene of Toxic Shock Syndrome Toxin-1 S. aureus Isolate from the Milk of Cows and Goats by Polymerase Chain Reaction

Abstract Staphylococcus aureus is the main bacterium found in cow's and goat's milk. The bacteria can produce toxin called toxic shock syndrome toxin-1 (TSST-1) that can infect humans and animals causing several serious diseases. The objective of this study was to detect the existence of encoding gene of TSST-1 S. aureus isolate from cow's and goat's milk. The research is initiated by re-identification stage of S. aureus conventionally continued by identification based on the molecular method of polymerase chain reaction (PCR). A number of 10 S. aureus isolates from cow's and goat's milk cultured in aerobics continued by Gram stain, catalase, coagulase, MSA, VJA and VP tests. The identification of S. aureus based on the molecular approach conducted by 16S rRNA gene amplification continued with amplification of TSST-1 encoding gene as the target gene. The PCR product of TSST-1 encoding gene then sequenced to ensure whether the DNA fragment amplified is the TSST-1 encoding gene or not. The result of the research indicates that re-identification of S. aureus conventionally generating positive reaction of S. aureus species. Molecular identification of 16S rRNA gene amplification gives a good result by producing DNA fragment of 745 bp size and meets the target gene. The detection result of encoding gene TSST-1 gives negative result marked by DNA fragment which the size does not match the target gene. The allignment result of sequence isolate SA.1 indicates that the sequence is not tst gene but the gene which coded glutamate sinthetase belongs to S. aureus, whereas sequence of isolate KI.8 is 50S rRNA gene belongs toS. saprophyticus.

Evaluation of Coagulase-Positive Staphylococcus Aureus Contamination in Lighvan Cheese on Retail Stores

Background: Staphylococcus aureus is a Gram-positive, non-sporulated, lack of capsule, immovable, aerobic and anaerobic and able to tolerate high levels of salt (up to 15 percent). Therefore, foods containing salt provides an ideal environment for bacterial growth. It is also one of the most important bacterial born of spoilable food products, especially in dairy products. Lighvan traditional cheese is consumed in many regions of Iran, especially consumption of these cheeses is very high in Tehran which in the manufacture of such cheeses, the unpasteurized and raw milk is used and the sanitary conditions during processing and subsequent storage are low. So, considering the importance of this issue in the release of poisoning, the coagulase-positive Staphylococcus aureus contamination in Lighvan cheese on Retail Stores was evaluated. Materials and Methods: In order to perform this study, 22 samples of traditional Lighvan cheese were collected randomly from Tehran stores and according to Iran national standards and by using of bird-parker, Cook Meat cultures and coagulase test were evaluated. Results: Total of 22 samples, 14 samples (63/6) were contaminated by S. aureus over standard and 5 (22/7) were contaminated with Staphylococcus aureus coagulase positive. Conclusion: This study demonstrated that sanitary conditions should be observed during the production and Use of pasteurized milk in cheese production.

Prevalence and Antibiotic Susceptibility Pattern of Methicillin Resistant Staphylococcus aureus in Tertiary Care Hospitals

Aims: Methicillin resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in hospitals with hospital based outbreaks world-wide. The present study was carried out to estimate the prevalence of MRSA isolates in clinical specimens and to investigate the sensitivity pattern of resistant isolates against various antibiotics used for treating hospitalized patients. Study Design: The percentage of MRSA was defined as the number of S. aureus isolates resistant to methicillin divided by the total number of S. aureus isolates for which methicillin susceptibility test results were reported. Place and Duration of the Study: The study was conducted during January 2012 to December 2012 at Asian Hospital (tertiary care hospital), Faridabad, Delhi. Methodology: A total of 107 isolates of S. aureus were identified by standard laboratory procedures including catalase test, slide and tube coagulase tests, βhaemolysis on blood agar and growth on mannitol salt agar. Subsequently, antibiotic sensitivity pattern of S. aureus were determined by automated antibiotic susceptibility testing system Vitek 2 compact identification and susceptibility testing (ID/AST) system by using AST-GP-67 card. Result: 23 isolates (21.4%) were identified as MRSA and the remaining 84 (78.6%) were Original Research Article British Biotechnology Journal, 4(3): 228-235, 2014 229 methicillin sensitive S. aureus (MSSA). All MRSA isolates were found to be resistant to penicillin, oxacillin, ciprofloxacin and levofloxacin. The antibiotic resistance pattern of these isolates were high against trimethoprim-sulfamethoxazole (91.3%), erythromycin (47.8%), gentamicin (43.5%), moxifloxacin (42.9%), and less resistance rate was observed against tetracycline (30.4%) rifampicin (13.6%) and clindamycin (4.8%). However, all isolates of Staphylococcus were sensitive to vancomycin, linezolid, nitrofurantoin, quinpristin/daflopristin. Conclusion: Findings presented in this study indicated a high level of resistance to widely used therapeutic agents. An appropriate knowledge on the current antibiotic susceptibility pattern of MRSA is essential for appropriate therapeutic scenario.

Evaluation of direct tube coagulase test in diagnosing staphylococcal bacteremia.

Blood Stream Infections (BSIs) are one of the most common nosocomial infections encountered in a hospital. It occurs 2 to 7 times more often in ICU patients than in ward patients and is associated with high rates of mortality and morbidity. Staphylococci is the most commonly encountered blood culture isolates for which, rapid and reliable methods for detection are warranted. To study the efficiency of direct tube coagulase test (DTC) in comparison with slide/tube coagulase test for early detection of Staphylococcal bacteraemia. This was a prospective study conducted in a tertiary care hospital, between January 2009 to December 2009. Two sets of blood cultures were obtained from each patient with a suspicion of Staphylococcal bacteremia. Both, direct tube coagulase test and conventional biochemical tests were done on the samples, to identify the species. Cohen's kappa coefficient of agreement was used to detect the differences between the two modes of detection. Ninety four samples (out of 460) yielded the growth of Gram positive cocci in clusters. The commonest isolates were Staphylococcus aureus (42.5%), Staphylococcus epidermidis (36.2%), Staphylococcus haemolyticus (8.6%), Staphylococcus cohnii (4.3%). Cohen's kappa coefficient which implies the extent of agreement of the results between the Direct Tube Coagulase test and conventional methods, was 95.6% along with sensitivity of 95.5% and specificity of 100%. Direct Tube Coagulase test (DTC) can be used for early detection of Staphylococcal bacteremia. It shows an almost perfect agreement with conventional coagulase test.

A systemic review of antimicrobial resistance pattern of methicillin-resistant Staphylococcus aureus

Antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) continues to be a problem for clinicians worldwide. It poses a serious therapeutic problem, leading to prolonged hospital stay and increased health-care costs. Current therapeutic options for MRSA are limited few expensive drugs. This study is a systematic review of published studies on MRSA and evaluates their antibiotic resistance pattern, and major finding as related to the objective of the study. Antimicrobial resistance of MRSA is based on CSLI guidelines-either disc diffusion or MIC methods. MRSA detection is either by classical methods for determining MICs (disc diffusion, Etest, or broth dilution), or screening techniques with solid culture medium containing oxacillin/cefoxitin and methods that detect the mecA gene or its protein product (PBP20 protein); S. aureus isolation should be based on standard bacteriological procedures: Tube/slide coagulase test or specific test like Pastorex or StaphID. A total of 33 studies were identified investigating the antimicrobial resistance of MRSA; of which 19 were included in the review. The majority of studies reported high levels of MRSA resistance against different antimicrobials. However, low levels of vancomycin resistance have been reported. Therefore, the knowledge of antimicrobial resistance of MRSA becomes necessary in the selection of appropriate empirical treatment of these infections. In addition, by employing a variety of prevention strategies, marked progress can be achieved in the control of drug-resistant pathogens, which can translate into more effective antimicrobial therapy.

Anesthesiologist's hand hygiene and disinfection of reusable rubber tourniquet with alcohol swabs before intravascular cannulation.

Anesthesiologist's hand hygiene and disinfection of reusable rubber tourniquet with alcohol swabs before intravascular cannulation.

Prevalence of Community-Acquired Methicillin-Resistant Staphylococcus aureus Nasal Colonization Among Children.

Invasive infections from community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are increasingly being encountered in healthy children. Nasal colonization of MRSA is associated with increased risk for acquiring invasive disease. The objective of this study was to determine prevalence and risk factors for CA-MRSA nasal colonization among a healthy paediatric population and to determine antibiotic susceptibilities of S. aureus isolates. Using a cross-sectional study design, children aged 1mnth-17y attending well-child clinic at an academic hospital and a local public school in Mangalore, India were screened for S. aureus colonization via nasal swabs. A questionnaire was administered and data on risk factors for nasal colonization was collected. Samples were obtained from the anterior nares and cultured quantitatively. S. aureus isolates were confirmed by growth on selective media and coagulase testing. Disk diffusion antibiotic susceptibility tests were performed according to Clinical and Laboratory Standard Institute guidelines. Of the 500 children included in the study, S. aureus was isolated from the anterior nares in 126 (25%) children; four (3%) isolates were classified as CA-MRSA. Factors associated with S. aureus nasal colonization were children <6 y old (p=0.030) and members of joint families (p=0.044). Resistance to many classes of antibiotics were noted among S. aureus isolates including trimethoprim-sulfamethoxazole (39%), ciprofloxacin (16%), erythromycin (19%) and clindamycin (5%). Inducible clindamycin resistance (positive D test) was detected in 11 of the erythromycin-resistant strains not already classified as resistant to clindamycin. No resistance to vancomycin was observed. Children in India have a high rate of nasal colonization of S. aureus. Nasal colonization of community-associated methicillin-resistant S. aureus exists but is still low among healthy children. The high rate of resistance to many classes of antibiotics among S. aureus strains is of great concern warranting continued surveillance and antimicrobial stewardship.

Virulence, Speciation and Antibiotic Susceptibility of Ocular Coagualase Negative Staphylococci (CoNS).

Coagulase negative Staphylococci (CoNS) are common inhabitants of human skin and mucous membranes. With the emergence of these organisms as prominent pathogens in patients with ocular infections, investigation has intensified in an effort to identify important virulence factors and to inform new approaches to treatment and prevention. To isolate CoNS from ocular specimens; to study the possible virulence factors; speciation of coagulase negative staphylococci (CoNS) which were isolated from ocular complications; antibiotic susceptibility testing of ocular CoNS. The specimens were collected from the target patients who attended the Microbiology Laboratory of a tertiary care eye hospital in Coimbatore, Tamilnadu state, India. The isolates were subjected to tube and slide coagulase tests for the identification of CoNS. All the isolates were subjected to screening for lipase and protease activities. Screening for other virulence factors viz., slime production on Congo red agar medium and haemagglutination assay with use of 96-well microtitre plates. These isolates were identified upto species level by performing biochemical tests such as phosphatase test, arginine test, maltose and trehalose fermentation tests and novobiocin sensitivity test. The isolates were subjected to antibiotic susceptibility studies, based on the revised standards of Clinical and Laboratory Standards Institutes (CLSI). During the one year of study, among the total 260 individuals who were screened, 100 isolates of CoNS were obtained. Lipolytic activity was seen in all the isolates, whereas 38 isolates showed a positive result for protease. A total of 63 isolates showed slime production. Of 100 isolates, 30 isolates were analyzed for haemagglutination, where 4 isolates showed the capacity to agglutinate the erythrocytes. The results of the biochemical analysis revealed that of the 100 isolates of CoNS, 43% were Staphylococcus epidermidis. The other isolates were identified as S. xylosus (n=8), S. captis (n=16), S. haemolyticus (n=10), S. saccharolyticus (n=2), S. hominis (n=5), S. saprophyticus (n=6) and S. intermedius (n=1). On the other hand, 9 isolates were not identified. In the antibiotic susceptibility analysis, it was found that most of the isolates were sensitive to vancomycin, amikacin and linczolid and resistant to cefatoxime, oxacillin, bacitracin and nalidixic acid. S. epidermidis was found to be predominant in causing the ocular complications. Slime production, heamagglutination, protease and lipase activities could be the putative virulence factors of CoNS. Antibiotic susceptibility patterns of CoNS against antibacterial agents revealed maximum resistance to beta lactam groups, and the resistance was found to be higher to oxacillin, and lowest to vancomycin.

Isolation and identification of some aerobic bacterial flora from female genitalia in Goats in Babylon city

The aerobic bacterial flora of the reproductive tracts were investigated using seventeen goats slaughtered at Al-Hilla Medhatiea slaughterhouse. Samples were collected aseptically from the vagina, cervix, uterine body, right and left uterine horns and right and left oviducts and for bacteriological examination. Standard microbiological techniques were used for isolation and identification of bacterial species. From a total of 119 specimens collected for bacteriological examination from cervix, uterine body, right and left uterine horns, right and left oviducts and vagina (17 each). Bacterial species identified were Staphylococcus aureus (30.25%) is the highest percentage which were positive for coagulase test, Escherichia coli(26.89%), Staphylococcus epidermidis and Streptococcus Spp. (10.93%) , Proteus mirabilis. (8.4%),the pseudomonas aeruginosa (6.72%),and finally Listeria monocytogenes (5.88%), from the positive results, were isolated from all the anatomical sites examined. In a nutshell, Staphylococcus aureus were dominant in this environment, followed by Escherichia coli.

유제품과 육제품에서 황색포도상구균 신속검출을 위한 PCR법의 비교검증

본 연구에서는 유제품 및 육제품에서 Staphylococcus aureus를 검출하기 위한 PCR과 배지배양법을 비교검증 하였다. 우유, 분유, 소시지, 소고기 분쇄육에 S. aureus를 인위적으로 접종시킨 후, 축산물 가공기준 및 성분규격에 따라 10% NaCl이 첨가된 tryptic soy broth(TSB)에서 증균배양 하였으며, Baird Parker agar에 선택배양 하였다. PCR은 TSB에서 1 mL를 채취한 후 DNA를 추출하여 시행하였으며, S. aureus의 23s rRNA를 표적으로 하는 primer를 사용하였다. 의심집락에 대해 coagulase test와 colony PCR을 통한 확인시험을 실시하였다. 실험결과 우유와 분유에서는 배지배양법과 PCR간에 통계학적 유의차가 존재하지 않았다. 소시지와 소고기 분쇄육의 경우에는 PCR이 배지법에 비해 더 많은 양성을 검출하여 높은 통계학적 유의차를 보였다(p<0.05). 연구결과를 종합하면, 유제품 및 육제품에서 PCR을 통한 S. aureus의 검출은 기존 배지배지배양법에 비해 시간과 노동력을 절감할 수 있는 효과적인 방법으로 나타났다. The aim of this study was to compare the performance of a standard culture method and polymerase chain reaction (PCR) for the detection of Staphylococcus aureus (S. aureus) in milk and meat products. Milk, dried infant formula, sausage and ground beef that had been artificially inoculated with S. aureus were enriched in tryptic soy broth. After the enrichment, a loopful was inoculated onto Baird-Parker agar with egg-yolk-tellurite. In parallel, 23S rRNA was amplified by PCR from samples of the enriched broth. Suspected S. aureus colonies grown on selective agars were finally confirmed by a coagulase test and colony PCR. No significant statistical differences were observed between the incidence of S. aureus detected by the culture method and the incidence detected by PCR, in milk or dried infant formula. However, in sausage and ground beef, the number of positives detected by PCR was significantly higher than by the culture method (p<0.05). Our findings suggest that PCR could be an effective screening tool for the detection of S. aureus compared to the standard culture method.

Comparison of Hypervariable Region (HVR) of mecA Gene in Staphylococcus aureus Isolated From Nasal Carriers and Clinical Samples

Background:: Methicillin Resistant Staphylococcus aureus (MRSA) is a common major human pathogen that causes hospital-acquired infections. Characterization and typing of the staphylococcal cassette chromosome has led to a better understanding of MRSA infection cycle in hospital. The mecA-associated hypervariable region size classifies MRSA isolates that colonized in nasal carriers. Objectives:: The aim of this study was to compare the genetic background of hypervariable region (HVR) of mecA gene in S. aureus isolated from nasal carriers and clinical samples. Materials and Methods:: A cross sectional study was performed on 261 nasal swabs collected from healthy health care workers (HCW) and 109 clinical samples from Tehran university hospitals. All the S. aureus isolates were identified by biochemical tests (Coagulase, Catalase, Manitol fermentation, and DNase tests). S. aureus isolates were investigated for the variability of HVR of mecA gene by PCR method. Results:: Among 261 collected nasal swabs, 70 (27%) were S. aureus. Of these, 29(41%) isolates were resistant to Oxacillin and 32 (46%) of those had mec-HVR gene. The polymerase chain reaction (PCR) products showed five different patterns of HVR. Also among 109 clinical samples, 52 (48%) of them were S. aureus. Of these, 40 (77%) were resistant to Oxacillin and 45 (87%) of them carried the mec-HVR gene. The PCR products showed 11 different patterns of HVR. Conclusions:: Molecular typing of MRSA isolates by HVR amplification has shown a high diversity among the strains and can be used as a basis for tracking the contaminations and the source of hospital infections from staff to patients and vice versa.