Speciation Of Coagulase Negative Staphylococci Research Articles

STUDY OF SPECIES IDENTIFICATION AND ANTIMICROBIAL SUSCEPTIBILITY OF VARIOUS CLINICAL ISOLATES OF COAGULASE – NEGATIVE STAPHYLOCOCCI

BACKGROUND- Interest in CoNS is increasing because of their role as pathogens in certain clinical conditions and their marked resistance to antibiotics. Frequent isolation of CoNS from the blood, other normally sterile body fluids, intravenous catheters and various tissues presents a recurrent interpretative challenge to both the clinician and microbiologist. The ubiquity of these organisms does present problems when one is faced with making a decision as to whether their isolation in clinical laboratory represents true infection or merely contaminant .AIM-The aim of this study was to isolate, identify and speciate coagulase negative staphylocci (CoNS) from clinical specimens, along with to find their resistance to antimicrobial agents with reference to their methicillin resistance .MATERIAL & METHOD - Various clinical specimens like blood, pus, wound swab, ascitic / synovial fluid, urine, cerebro spinal fluid were processed in laboratory following the standard protocol for isolation, identification and speciation of coagulase negative staphylococci. RESULT- Present study found, S. epidermidis to be most prevalent species of coagulase negative staphylocci from clinical isolates with 47.58% strains, followed by S. haemolyticus 26.06%, and S. lugdunensis 8.54%. S. saprophyticus was the most common of CoNS species from urinary tract infection cases. Methicillin resistant CoNS (MRCoNS) were detected by cefoxitin disk diffusion method Out of 234 strains of CoNS, 153 strains (65.38%) were detected as MRCoNS. Most of the MRCoNS were found to be resistant to penicillin (100%), ceftazidime (99.35%), amoxicillin-clavulanic acid (98.69%), cotrimoxazole (92.81%), gentamicin (88.23%).Susceptibility to vancomycin and pristinamycin was 86.93 % and 99.35% respectively while all the MRCoNS isolates were susceptible to linezolid. CONCLUSION - Vancomycin is the mainstay of therapy in MDR MRCoNS infections and should be used judiciously. Looking at the possibility of emergence of resistance to the drug, newer agents like linezolid and pristinamycin might provide a valuable option for the treatment of MRCoNS infections. There is a need to have the knowledge and monitoring of antibiotic sensitivity pattern and formulation of definite antibiotic policy to improve the empirical approaches to the therapy of serious infections caused by CoNS

Speciation of coagulase negative staphylococci (CoNS) isolated from various clinical specimens in a tertiary care hospital of southern Rajasthan

Abstract Background: Coagulase negative staphylococci (CoNS) are a group of staph bacteria, which generally exist as normal flora of human skin and the oral flora found on mucous membranes. CoNS in immunocompromised patients can cause variety of infections like bacteraemia, central nervous system shunt infection, intravascular catheter-related infections, endocarditis, surgical site infections, urinary tract infections, foreign body infection, endophthalmitis, peritonitis and wound, bone and joint infections as well as infections in neonates. These infections are difficult to treat because of the risk factors and the drug resistant nature of the organisms.Objective:To find out species wise distribution of Coagulase negative Staphylococci (CoNS) in various relevant clinical samples in our institute. Materials and Method:A total of 500 CoNS strains were isolated from relevant clinical specimens. CoNS strains were isolated from variety of clinical specimens. Strains were identified as CoNS on the basis of colony morphology, gram stain, catalase test and coagulase test. Conventional methods were used for species identification after confirming isolates as CoNS. Results:The most common source of CoNS isolation was blood (34%), followed by respiratory secretions (24.4%), urine (16.8%), pus (13.4%), swabs (5.4%), bodily fluid (1.4%), and others (4.6%). S.epidermidis was most frequently isolated (30.6%), followed by S.hemolyticus (25.4%), S.hominis (12.6%), S.capitis (12%), S.lugdunensis (11.4%) and S.cohnii (08%). Conclusion : As CoNS have become major cause of nosocomial infections, there is a need for rapid identification and speciation of CoNS with their antibiotic susceptibility for better management of these cases and to prevent emergence of drug resistance.

Speciation and Antibiotic Susceptibility Pattern of Coagulase Negative Staphylococci in a Tertiary Care Hospital of Manipur, India

Introduction: Coagulase Negative Staphylococci (CoNS) are common opportunistic pathogens. They are increasingly being recognised as nosocomial pathogens and are associated with multiple antimicrobial resistance mechanisms particularly methicillin resistance. Therefore, rapid and reliable identification upto the species level is necessary to predict the potential pathogenicity or antibiotic susceptibility of each clinical isolate. Aim: Isolation and speciation of CoNS from various clinical samples, and to determine their antibiotic susceptibility pattern. Materials and Methods: This study was a hospital-based crosssectional study carried out in the Department of Microbiology, Jawaharlal Nehru Institute of Medical Sciences (JNIMS), Imphal, Manipur, India, during the period from September 2017- August 2019. CoNS isolates were identified using conventional microbiological procedures and speciation was done following the scheme of Kloos and Schleifer. Antibiotic susceptibility was determined by using the Kirby Bauer’s disk diffusion method. Detection of methicillin resistance among CoNS was performed using cefoxitin disk (30 µg) diffusion method. Data analysis was done using descriptive statistics. Results: CoNS isolates were identified from different clinical specimens, which included 88 (65.2%) from urine, 37 (27.5%) from blood, 3 (2.2%) from pus, 2 (1.5%) from catheter tip, 2 (1.5%) from wound swab, 1 (0.7%) each from aural swab, sputum and ascitic fluid. Predominant isolates were Staphylococcus epidermidis (40.7%) followed by Staphylococcus haemolyticus (19.3%), Staphylococcus hominis (11.9%), Staphylococcus xylosus (7.4%), Staphylococcus saprophyticus (6.0%), Staphylococcus schleiferi (5.2%), Staphylococcus simulans (4.4%), Staphylococcus warneri (3.0%), Staphylococcus lugdunensis (0.7%), Staphylococcus capitis (0.7%) and Staphylococcus cohnii (0.7%). Most isolates were resistant to penicillin (84.5%) and erythromycin (59.3%), and least to tigecycline (2.2%). No resistance to vancomycin and linezolid was seen. Methicillin sensitive CoNS (MSCoNS) was detected in 79 (58.5%) isolates and methicillin resistant CoNS (MRCoNS) in 56 (41.5%) isolates. Conclusion: This study demonstrated the occurrence of various species of CoNS in our healthcare set up with varying antimicrobial susceptibility pattern. Therefore, there is a need for accurate identification to species level by simple, inexpensive methodology and their antibiogram.

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.

Speciation of coagulase negative staphylococci, isolated from indoor air, using SDS page gel bands of expressed proteins followed by MALDI TOF MS and MALDI TOF-TOF MS-MS analysis of tryptic peptides

A group of coagulase negative staphylococcal strains isolated from indoor air of occupied school rooms were the subject of this study. Conventional MALDI TOF MS profiling of cellular extracts and physiological tests (including API STAPH) provided incomplete identification of the set of strains. After separation of a 100 kDa band using 1D gel electrophoresis, profiling of peptides (released with tryptic digestion) using MALDI TOF MS allowed improved bacterial speciation in addition to determination of the identity of the protein of origin (aconitate hydratase). This was performed by Mascot search, empirical observation and computer-generated cross-correlation analysis of environmental isolates versus reference strains. The species studied included some with sequenced genomes and others with un-sequenced genomes. Peptide sequences were confirmed to originate from aconitate hydratase using MALDI TOF-TOF MS-MS analysis of a diverse set of m/ z values representing variable and conserved sequences. The methodological approach described here might have widespread application in speciation of environmental isolates of diverse origin and in identification of their expressed proteins.

Microbiologic studies of coagulase-negative staphylococci isolated from patients with nosocomial bacteraemias

We studied 50 strains of coagulase-negative staphylococci (CNS) isolated from 50 patients with hospital-acquired bacteraemia, identified by prospective surveillance at the University of Virginia Hospital between March 1981 and September 1982. Using the Staph-Ident System for speciation, we found that 37 strains (74%) were Staphylococcus epidermidis, 7 (14%) Staph. hominis, 3 (6%) Staph. haemolyticus and 3 (6%) Staph. warneri. 33 (66%) of the strains produced slime and a higher proportion of the Staph. epidermidis group (75%) than the non-epidermidis group (46%), did so Minimal inhibitory concentrations (MIC) were determined by a microdilution technique with 20 different antibiotics. There was no difference in geometric mean MICs between slime producers and non-slime producers within either the epidermidis or non-epidermidis group. The most potent antibiotics against Staph. epidermidis (MIC 90 mg 1 −1) were rifampin (0·05), netilmicin (0·05), amikacin (2·9), thienamycin (0·75), teichomycin (0·85), vancomycin (1·0) and nafcillin (0·39). On the other hand strains were resistant to tobramycin (15), moxalactam (50), fosfomycin (64), and clindamycin (64). Overall, eight (16%) of the CNS strains were resistant to methicillin, three of which were Staph. haemolyticus. The non-epidermidis strains were more resistant than the Staph. epidermidis strains to most β-lactam antibiotics. Differences in antibiograms indicate that speciation of CNS may prove useful for clinical and epidemiologic purposes.

Speciation of coagulase-negative staphylococci in the clinical laboratory.

The purpose of this study was to evaluate the efficacy of the API Staph System for the speciation of coagulase-negative staphylococci. Three hundred and seventy-one coagulase-negative clinical isolates were studied; 50% of these could be speciated using the code profiles of the API System. By reference to the Kloos and Schleifer schema, 93% of the isolates could be speciated. The distribution of the various staphylococcal species in clinical specimens was determined. It was concluded that the API Staph System would be a satisfactory method of speciation if the data base could be expanded. Such speciation may at times be helpful in interpreting the significance of coagulase-negative staphylococcal isolates in the clinical laboratory.

Bacterial culture of perfusion blood after open-heart surgery.

The results of routine culture of 595 consecutive specimens of perfusion blood are presented. Ten per cent of the specimens yielded bacteria overall, but it was found that the isolation rate was increased to 17.7% when the prophylactic antibodies being given during the bypass were specifically neutralised. Coagulase-negative staphylococci and diphtheroids formed the majority of organisms isolated, but Gram negative bacilli or "coliform" type were also occasionally found. A comparison of the relative findings in patients receiving prophylactic flucloxacillin or cephradine showed that the isolation rates of coagulase-negative staphylococci and diphtheroids were lower in the group receiving flucloxacillin. The origin of the bacteria isolated from perfusion blood remains uncertain but speciation of coagulase-negative staphylococci from perfusion blood and similar organisms isolated subsequently from catheter tips in the same patients revealed no evidence that the two sources of organisms were linked. Although organisms are easily and commonly found in perfusion blood, the relevance of this phenomenon to post-operative endocarditis is not clear.