Speciation of coagulase negative Staphylococcal isolates from clinically significant specimens and their antibiogram.

Background: Despite their frequency as contaminants, coagulase-negative Staphylococci (CONS) have become important nosocomial pathogens, accounting for 9% of all nosocomial infections. These infections are diffi cult to treat because of the risk factors and the multiple drug resistance nature of these organisms. Materials and Methods: One hundred and two consecutive CONS were isolated from various clinical samples like blood, pus, urine, urine catheter tip and gastric lavage. Most of the blood samples were from patients with risk factors (immunocompromised or on medical devices). After confi rming the isolates as CONS, species-level identifi cation was performed by simple, non-expensive conventional methods and antibiotic sensitivity testing was also carried out. Results: Of 102 CONS isolates, 100 isolates could be identifi ed to the species level. Among the 100 isolates, epidermidis was the most common species isolated, seen in 32%, followed by S. hemolyticus (18%), S. lugdunensis (12%), S. hominis (10%), S. saprophyticus (8%), S. capitis (6%), S. caprae (4%), S. xylosus (4%), S. cohni and S. warneri (3% each). In the present study, 56% of the isolates were methicillin-resistant CONS. Most of the isolates showed resistance to ampicillin and amoxyclav (89% each), followed by ceftriaxone (52%), cotrimoxazole (46%), cefotaxime (32%), gentamicin (25%), amikacin (21%). Conclusion: The increased pathogenic potential and multiple-drug resistance demonstrates the need to adopt simple, reliable and non-expensive methods for identifying and determining the antibiotic sensitivity of CONS.

Phenotypic methods for determination of methicillin resistance in Staphylococcus spp. from health care workers / Métodos fenotípicos para determinação da resistência à meticilina em Staphylococcus spp. de profissionais de saúde

INTRODUCTION: Staphylococcus spp. is an important healthcare-associated pathogen and the identification of methicillin-resistant strains in samples of colonization may provide data to assist in the antimicrobial therapy success. OBJECTIVES: To determine the occurrence of colonization by methicillin-resistant Staphylococcus spp. (MRS), through the detection of the mecA gene and to evaluate different phenotypic methods for the presumptive detection of methicillin resistance in samples of the anterior nasal cavity and hands of the health care personnel of a university hospital in the state of Pernambuco, Brazil. METHODS: We selected the 28 isolates of Staphylococcus spp., which showed an intermediate or resistant phenotypic profile for oxacillin, detected by the Kirby Bauer technique. The methods used were disk-diffusion tests for cefoxitin, minimal inhibitory concentration by E-test for oxacillin, screening for oxacillin resistance and mecA gene detection by polymerase chain reaction (PCR). RESULTS: About the phenotypic methods utilized, only the E-test of oxacillin did not show a statistically significant difference in relation to PCR for the mecA gene detection, considered the gold standard. CONCLUSION: The E-test of oxacillin was the best of the phenotypic methods utilized. It is necessary to correctly detect MRS in healthy individuals, because they can act as carriers and can therefore be a potential source of microorganisms involved in hospital infections.

INTRODUÇÃO: Staphylococcus spp. é um importante patógeno associado aos cuidados em saúde, e a identificação de isolados resistentes à meticilina em amostras de colonização pode fornecer dados para auxiliar no sucesso da terapia antimicrobiana. OBJETIVOS: Determinar a ocorrência de colonização por Staphylococcus spp. resistentes à meticilina (MRS) por meio da detecção do gene mecA e avaliar diferentes métodos fenotípicos para a detecção presuntiva da resistência à meticilina em amostras da cavidade nasal anterior e das mãos de profissionais de saúde de um hospital universitário no Estado de Pernambuco, Brasil. MÉTODOS: Foram selecionados 28 isolados de Staphylococcus spp. que mostraram perfil intermediário ou resistente à oxacilina, detectado pela técnica de Kirby Bauer. Os métodos utilizados foram o teste de disco difusão de cefoxitina, concentração inibitória mínima pelo E-test de oxacilina, screening para avaliação da resistência à oxacilina e reação em cadeia da polimerase (PCR) para detecção do gene mecA. RESULTADOS: Dos métodos fenotípicos utilizados, apenas o E-test de oxacilina não mostrou diferença estatística significante em relação à PCR para a detecção do gene mecA, considerado o método padrão-ouro. CONCLUSÃO: O E-test de oxacilina foi o melhor método fenotípico utilizado. É necessário detectar corretamente o MRS em indivíduos saudáveis, pois eles podem atuar como portadores, sendo uma fonte potencial de microrganismos envolvidos em infecções hospitalares.

Study of antimicrobial susceptibility of clinically significant microorganisms isolated from selected areas of Dhaka, Bangladesh.

Objective: Pathogenic resistance against antibiotics is substantially mounting in the developing countries including Bangladesh. Present study thus attempted to obtain the baseline information on such resistance among the community people coming to the local dispensaries around the city of Dhaka for treatment. Materials and Methods: A total of 2,700 clinical specimens were examined for the presence of Gram positive and Gram negative pathogens. Antibiotic susceptibility tests of the isolates were carried out. Extended spectrum b- lactamase (ESBL) activity, and the presence of methicillin resistant Staphylococcus aureus (MRSA) and S. epidermidis (MRSE) were also detected. Results: Escherichia coli were most prevalent (45.5%) among 1044 pathogenic bacteria isolated from 2,700 samples. E. coli predominated urine, pus, wound swab, blood, high vaginal swab (HVS) and sputum specimens, and exhibited the highest frequency of ESBL activity (35%). Prevalence of Klebsiella spp. and S. aureus among the clinical specimens were 11.5% and 9.86%, respectively. Most of the Gram negative bacilli were found resistant against ciprofloxacin (5 mg), tetracycline (30 mg) and cotrimoxazole (25 mg). Majority of Pseudomonas spp. were found resistant against most of the commonly used antibiotics. Interestingly, around half of the S. aureus isolates were observed to be methicillin resistant, but not vancomycin resistant. Conclusion: Overall, such a revelation of increased antibiotic resistance demands for restrictive and appropriate antibiotic usage in accordance with the updated antibiotic prescribing policy in Bangladesh.

Comparison of teicoplanin disk diffusion and broth microdilution methods against clinical isolates of Staphylococcus aureus and S. epidermidis

The CLSI M100-S19 document has recommended the disuse of vancomycin disks for staphylococci and informed that studies on the action of teicoplanin in disk-diffusion testing should be performed. We describe the comparison of two methods, disk diffusion and broth microdilution, for determining teicoplanin susceptibility in clinical isolates of staphylococci. Overall results showed an aggregation rate of 96.8 percent; Staphylococcus aureus showed total agreement while S. epidermidis showed 93.8 percent of agreement. According to these local results, disk diffusion can still be employed to teicoplanin susceptibility determination for staphylococci in our institution.

Different effects of airway epithelial cells transfected by elafin on bacterial biofilm / 基础医学与临床

Objective To explore the different effect of elafin incubated by different bacteria on P.aeruginosa(Pa) bioflim. Methods To cultivate the A549 cells in vitro, the pEGFP-N1-elafin eukaryotic expression vectors have been transfected to the cells by LipofectamineTM 2000. Elafin transfected cells incubated by the supernatant of S. epidermidis (S.epidermidis group), Pa (Pa group) and E.coli (E.coli group) respectively for 24 hours,the A549 cells were transfected. Then the levels of elafin were detected by ELISA and Western blot. To establish the Pa biofilm model in vitro,a rapid silver nitrate staining procedure and scanning electronic microscope (SEM)demonstrated bacterial biofilm. After biofilm carriers were put into each group and incubated for 8 hours, we measured the proportion of bacteria biofilm by silver nitrate staining and observed the structure of biofilm by SEM. Results The Pa and E.coli groups(especially Pa) raised the content of elafin in cells and the level of secretion increasing as compared to the normal group, while the S. epidermidis group had no change. Both silver nitrate staining procedure and SEM demonstrated the prestnce of bacterial biofilms. The the proportion of bacteria biofilm and the structure of BF in Pa and E.coli groups were changed, especially in Pa group. Conclusion There was a specificity for bacteria to induce the express of elafin. The inducing effect of Pa was more significant than that of E.coli.

Antibacterial Activity for Prunus Mume Sieb et Zucc against 308 Clinical Isolates / 中国中医药信息杂志

Objective To observe antibacterial efficiency of Prunus mume Sieb et Zucc against clinical isolates. Method Antibacterial activity of Prunus mume Sieb et Zucc against 308 strains of clinical isolates were determined by agar dilution method. Results MIC50 of Prunus mume Sieb et Zucc against staphylococcus aureus (112 strains), S.epidermidis (112 strains), and Enterococci (28 strains) were 0.72, 1.44, 0.72 mg/mL, and MIC90 were 1.44, 1.44, 0.72 mg/mL respectively. The MIC90 of Prunus mume Sieb et Zucc to Klebsiella pneumoniae and E. coli were 2.88, 1.44 mg/mL respectively. Conclusion Prunus mume Sieb et Zucc has good antibacterial activity against Gram positive cocci and some Gram negative bacilli.

Molecular Epidemiology and Risk Factors of Staphylococcus epidermidis Isolated from Patients with Acute Leukemia / 병원감염관리

BACKGROUND: The purpose of this study is to define the risk factors of S. epidermidis acquisition and the epidemiology of strain variation in acute leukemia patients. METHODS: The participants were 155 patients of acute leukemia admitted in a University hospital for 11 months. 83 patients are the isolated group who had isolated S. epidermidis from body sites (blood, oral cavity, nares, rectum) and 72 patients are the not isolated group who had not isolated S. epidermidis. Isolates were analysed by CHEF and cluster analysis with dendrogram. Differences In proportions were tested with the Chi-square and Fisher's exact test. RESULTS: Ninety-one S. epidermidis were obtained from blood, oral cavity, nares, and rectum. The major proportion of positive culture was 81.3% from nares. Eight-nine S. epidermidis were isolated from healthcare workers. There were significant development of bacteremia in patients with S. epidermidis from nares. Resistance rate of S. epidermidis was 75.8% to methicillin, 86.3% to erythromycin, 81.l% to gentamicin, 68.9% to ciprofloxacin, 0% on vancomycin. There was significant difference on resistance rate between patients and healthcare workers' group. There was no relation between the strain of patients and those of healthcare workers. Sex age, diagnosis, length of stay, type of chemotherapy, duration of chemotherapy, Type of central venous catheter. duration of central venous catheter, prior antibiotic therapy, number of antibiotics, site of nosocomial infection, neutropenic period were not significantly different between S. epidermidis isolated group and not isolated group. Significant risk factors included duration of central venous catheter. hyper-alimentation, and folliculitis. CONCLUSION: Our result suggests that S. epidermidis in nares can be a risk factor of bacteremia. This research would be helpful for decreasing the S. epidermidis of immunocompromised patients.

Adherence and Biofilm Formation of Staphylococcus epidermidis and Mycobacterium tuberculosis on Spinal Implant / 대한척추외과학회지

STUDY DESIGN: Bacterial adherence and biofilm formation in implant associated infection may depend on species of microor-ganism, types of strains, the physical or chemical characteristics of the implant surfaces. OBJECTIVES: To evaluate the differences of adherence and biofilm formation between S. epidermidis and M. tuberculosis on smooth surfaced or rough surfaced stainless steel and titanium alloy, respectively. SUMMARY OF LITERATURE REVIEW: In implant associated infections, bacteria in biofilm are resistent to antibiotics or host defence mechanism and removal of implants is usually necessary to eradecate infection. On contrary, spinal instrumentation with complete debridement and antituberculosis chemotherapy is a safe procedure for spinal tuberculosis. MATERIALS AND METHODS: S. epidermidis and M. tuberculosis were cultured with 4 types of rod segments which consisted of smooth and rough surfaced stainless steel and titanium alloy, respectively. After isolation with trypsin treatment and culture on plate media, colony forming units (CFUs) were counted. The feature of adherence and biofilm formation were observed under scanning electron microscopy (SEM). RESULTS: Biofilm forming S. epidermidis showed heavy adhesion and multiplication on surface of all 4 rod segments, 16.5 times more CFUs than biofilm non-forming ones, especially on smooth surfaced stainless steel. On SEM field, there were many aggregated microcolonies with thick amorphous biofilm in biofilm forming S. epidermidis and much less in biofilm non-forming S. epidermidis. M. tuberculosis rarely adhered to metal surfaces. On SEM, there were few tubercle bacilli and scanty biofilm for-mation. CONCLUSIONS: Biofilm may play an important role in adhesion and multiplication of S. epidermidis but adherence and biofilm iformation of M. tuberculosis on implant surface are less likely and it can provide the basis of instrumentation in spinal tubercu-losis.

Adherence of Slime / 대한정형외과학회잡지

There were many studies to investigate the pathogenesis and prevention of infection in artificial joint replacement due to the difficulty in management of infected arthroplasty in spite of using large amounts of antibiotics. Biomaterials play a major role in the development of infection because of the way the body responds to their chemical and physical characteristics. Exopolysaccharide glycocalyx or biofilm(slime) which is produced by organisms adhered to the biomaterials has been detected and regarded as an important factor in pathogenesis. The production of slime on the biomaterials in turn makes the pathogens resistant to the antibiotics and therefore they survive. The objects of this study are to evaluate which materials are more susceptible to the adherence by Staphylococcus epidermidis, to evaluate the amount of antibiotics needed to kill the S. epidermidis adhered to the biomaterials(Polymethymethacrylate, Titanium-6Aluminum-4Vanadium alloy, Ultrahigh molecular weight polyethylene), and to evaluate the timing of administration of the antibiotics(cephradine, gentamicin) and potadine for prevention of postoperative infection. The results are as follows. 1. The materials in order of greatest adherence due to the number of organisms colonized are poly- methylmethacrylate(PMMA), ultrahigh molecular weight polyethylene(UHMWPE), and titanium alloy(Ti-6A1-4V alloy) being the least adherent. 2. With the production of biofilm the S. epidermidis becomes resistant to even that of 4 times the minimum bactericidal concentration(MBC) of antibiotics. 3. For prevention of postoperative infection, the prophylactic administration of cephradine if effective when used within 4 hours after contamination and the gentamicin and potadine are effective when used within 8 hours after the contamination with S. epidermidis.

In vitro activities of eight antibiotics against methicillin-resistant S. aureus and S. epidermidis strains isolated in Korea

Staphylococcus aureus and Staphylococcus epidermidis strains isolated at eight large medical centers in Korea were examined for methicillin resistance and resistance to eight other antibiotics; cefazolin, cefamandole, cefuroxime, cefoxitin, cefotaxime, moxalactam, penicillin G and vancomycin. Methicillin resistance was found in 296 of 1225 strains (24.2%) of S. aureus and 126 of 348 strains (36.2%) of S. epidermidis. Methicillinresistant strains were isolated from all sources with the frequency of isolation ranging from 11% to 60%. From pleural effusion, throat swab and blood, methicillin-resistant strains of S. aureus were more frequently isolated with statistical significance (Chi-squared test, 95% confidence). Almost all of Methicillin-resistant S. aureus (MRSA) and S. epidermidis (MRSE) strains were multiply resistant to one or more tested eight antibiotics. However only 7(2.4%) of 296 MRSA strains and 2(1.6%) of 126 MRSE strains were resistant to vancomycin. Vancomycin was the most effective antibiotic against staphylococcal isolates as well as MRSA and MRSE.