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PubMed2006

Phenotypic and technological diversity of lactic acid bacteria and staphylococci isolated from traditionally fermented sausages in southern Greece.

The physicochemical and microbiological characteristics of spontaneously fermented sausages made by two medium-sized enterprises (MSE) located in southern Greece have been studied. A total of 300 lactic acid bacteria and 300 staphylococcal strains have been isolated and identified by their physiological characteristics. Lactobacillus plantarum strains were found to dominate the lactic acid bacteria microbiota in most of the cases with L. sakei strains prevailing in some of them and L. rhamnosus strains occasionally accompanying the dominant lactic acid bacteria microbiota. On the other hand, S. saprophyticus strains were found to dominate the staphylococcal microbiota in all spontaneously fermented sausages with of S. simulans, S. xylosus, S. gallinarum and S. cohnii cohnii strains being sporadically present. Following the identification, an evaluation of their technological properties, namely proteolytic and lipolytic capacities as well as production of biogenic amines and antimicrobial compounds, took place. None of the lactic acid bacteria and staphylococci was found to possess lipolytic activity whereas a total of 6 lactic acid bacteria and 51 staphylococci strains were found to be able to hydrolyse either the sarcoplasic, myofibrillar or both protein fractions. Furthermore, only one L. sakei strain and 185 staphylococci strains were found to possess decarboxylase activity against lysine, tyrosine, ornithine or histidine. Finally none of the staphylococcal microbiota and 3 lactic acid bacteria strains were found to be able to produce antimicrobial compounds of proteinaceous nature against Listeria monocytogenes.

Animals↗
PubMed2006

Protease and esterase activity of staphylococci.

The aim of this work was to characterize protease and esterase activities of staphylococci in order to establish if they could contribute to the release of amino acids and short-chain fatty acids during ripening of fermented sausages. Eighteen Staphylococcus strains belonging to the species Staphylococcus xylosus (5), S. saprophyticus (3), S. equorum (4), S. carnosus (4) and S. simulans (2), previously isolated from different types of Southern Italian fermented sausages, were screened for proteinase, aminopeptidase and esterase activities. Most of the staphylococci strains lacked detectable levels of proteinase activity against casein-fluorescein isothiocynate. In the active strains, this activity was extracellular or cell-envelope associated. The studied staphylococci strains also showed low levels of aminopeptidase activities, which preferentially hydrolysed substrates containing L-methionine, L-leucine and L-phenylalanine as N-terminal residue. In contrast, all staphylococcal strains possessed significant activity against short-chain fatty acid esters. The maximum esterase activities were detected in whole-cell suspensions and cell-free extracts and to a lesser extent in the extracellular medium. The substrates preferentially hydrolysed were rho-nitrophenyl (rho-NP) butyrate and rho-NP caprylate and, secondly, rho-NP palmitate. The extracellular extracts of most of the strains were only active against rho-NP butyrate except for those of S. equorum (SI3, SI4) and S. simulans (Ssm12, Ssm21), which also hydrolysed rho-NP caprylate and rho-NP palmitate. The cell-free extracts and whole cells were mainly active against rho-NP butyrate and rho-NP caprylate, showing activity levels from 1760 U/mg of proteins to 54 U/mg of proteins and from 12,200 U/mg of proteins to 133 U/mg of proteins respectively. These activities were especially high in the strains that belonged to S. xylosus and S. equorum species. The diversity of the studied metabolic properties and, especially, the esterase activities in different staphylococcal species and even strains of the same species emphasize the relevance of these in vitro characterization studies for a rational selection of new starter cultures.

Aminopeptidases↗
PubMed2004

[Accuracy of four agar diffusion methods and the Vitek 2 automated system for the detection of the methicillin resistance in coagulase negative staphylococci].

AIM OF THE STUDY: Technical difficulties may occur in the detection of methicillin resistance in coagulase negative staphylococci. Phenotypic methods, such as disk diffusion testing, sometimes fail to detect methicillin resistance because of its poor expression. Four of these methods were compared with the VITEK 2 system. MATERIALS AND METHODS: The accuracy of the VITEK 2 system and the agar diffusion methods according to the current CASFM and NCCLS guidelines were assessed for methicillin susceptibility testing of 70 coagulase negative staphylococci isolates harboring the mecA gene for which the detection of the methicillin resistance was particularly difficult: the CASFM recommendations applied in 1998 failed to categorize them as methicillin-resistant. RESULTS: Among the different methods currently suggested by the CASFM, those using a heavy inoculum and a hypersaline medium give better results, but they remain however less efficient than the NCCLS recommendations testing (sensitivity: 71-86% vs. 94-94% respectively). The VITEK 2 was more efficient (sensitivity: 91%) than the disk diffusion methods recommended by the CASFM and slightly less efficient than the method recommended by the NCCLS. CONCLUSION: The VITEK 2 automated system, compared with the disk diffusion methods, showed adequate accuracy for detection of oxacillin resistance in coagulase negative staphylococci.

Coagulase↗
PubMed2002

[Staphylococci as uropathogens-frequency of isolation in hospitalized patients and sensitivity to antimicrobial agents].

For a period of 24 months (1997-1999) were isolated 266 clinically significant staphylococcal strains, S. aureus, 36 (13.5%) and 230 (86.5%) coagulase negative staphylococci (CNS) from urines of hospitalised patients (over 14 years) with UTI. The most frequently isolated strains from CNS was S. haemolyicus, 110 (47.8) strains, followed by S. saprophyticus 47 (20.4%) strains and S. epidermidis 18 (7.8%). The susceptibility of the isolates to 13 antimicrobial agents was determined by agar dilution method (NCCLS). From the isolated 36 strains S. aureus, 24 were sensitive and 12 were resistant to methicillin. From 230 CNS, 105 strains showed sensitivity and 125 strains resistance to methicillin. All staphylococci were sensitive to vancomycin and most of them (over 95%) to amikacin and rifampin. It was established a considerable difference between the sensitivity of methicillin-sensitive and methicillin-resistant staphylococci. The established resistance accompanied with high rate percentage methicillin resistance requires careful consideration to antimicrobial therapy of staphylococcal urinary tract infections (UTI).

Adolescent↗
PubMed2000

Spread of coagulase-negative staphylococci during cardiac operations in a modern operating room.

BACKGROUND: Coagulase-negative staphylococci cause 33% to 62.5% of wound infections after cardiac operations. The aim of this study was to investigate the sources of coagulase-negative staphylococci in the sternal wound. METHODS: Twenty operations performed in zonal ventilated operating rooms were investigated prospectively. Cultures were taken from all persons present in the room, the sternal wound, and the air. Isolates macroscopically judged to be coagulase-negative staphylococci were metabolically classified, and similar isolates were investigated by pulsed-field gel electrophoresis. RESULTS: Bacterial counts in the operating room air were very low. Wound contamination was found in 13 of 20 operations. Six wound isolates could be traced, three to the patients' sternal skin, one to the patient's groin, one to the surgeon's nose, and one to the surgeon's arm and forehead and the assistant's nose. Three operating field air cultures could be traced to the scrubbed theatre staff. The single case of superficial sternal wound infection was caused by Staphylococcus aureus, which was not isolated from the wound at operation. CONCLUSIONS: In an ultraclean environment, bacteria in the sternal wound originated from the patients' own skin and from the surgical team.

Adult↗
PubMed1989

Surface colonization with coagulase-negative staphylococci in premature neonates.

To follow the emergence of surface colonization with coagulase-negative staphylococci in neonates, we sampled four surface sites (axilla, ear, nasopharynx, and rectum) in 18 premature infants during the first 4 weeks of life. Swabs were obtained on the first day of life, twice weekly for 2 weeks, and weekly thereafter. Isolates were characterized by species, biotype, antibiotic susceptibility patterns, and slime production. Over 4 weeks the percentage of infants with Staphylococcus epidermidis as the only surface coagulase-negative staphylococci rose from 11% to 100%. Predominance of a single S. epidermidis biotype increased from none to 89%. Multiple antibiotic resistance rose from 32% to 82% of isolates, and the prevalence of slime production increased from 68% to 95%. This microbiologic pattern was established by the end of the first week of life and persisted throughout the month of study. In three infants, S. epidermidis sepsis developed with organisms identical to their predominant surface isolate. We conclude that species, multiple antibiotic resistance, and slime production appear to confer a selective advantage for the surface colonization of premature newborn infants in the intensive care nursery environment. Infants so colonized may be at greater risk for subsequent infection with these strains of coagulase-negative staphylococci.

Age Factors↗
PubMed1987

A model for the three-dimensional structure of peptidoglycan in staphylococci.

Although the monomeric units of peptidoglycan in Staphylococcus aureus and other staphylococci are well known, the complete structure of the peptidoglycan has not been elucidated. The peptidoglycan monomeric unit may be divided into three parts: (1) glycan chain piece, consisting of N-acetylglucosaminyl-N-acetylmuramic acid; (2) connecting peptide extending from L-alanine to the alpha-amino group of L-lysine; (3) peptide chain piece, consisting of D-alanine, the remainder of L-lysine not included in the connecting peptide, and pentaglycine (S. aureus) or mixed glycine and serine residues (other staphylococci) attached to the epsilon amino group of lysine. The deformation of cross wall into hemisphere in the course of cell division, the distensibility of peptidoglycan, and the appearance of circular (? spiral) lines in the cross wall and on the surface of the newly-formed hemisphere are clues to the structure of peptidoglycan. In the proposed model, cross wall is formed as a linear spiral with 20 turns extending in a plane from periphery to center of the cell. During cell division, the cross wall is bisected. The cross wall spiral becomes a spiral forming the peripheral wall of a new hemisphere. The width of the spiral on the cell surface is maintained by rigid glycan chains and by covalent bonds linking turns of the spiral. The length of the spiral is about 30 times the diameter of the cell. Flexible polypeptide sheets consisting of parallel polypeptide chains run along the length of the spiral. Individual polypeptides contain an average of ten peptide chain pieces. The glycan chain is a helix with two disaccharide residues per turn; consequently consecutive connecting peptides project in opposite directions and are perpendicular both to the glycan chain and to the peptide chain. In cross wall, hydrogen bonding between polypeptide chains enables the polypeptide sheet to transmit changes in tension. The deformation of cross wall into peripheral wall requires doubling of the external surface area of the peptidoglycan. A change in the angle of the glycan chain with respect to the peptide chain results in an increase of the distance between peptide chains, causing the doubling of surface area. Implications of the model include explanations for the initiation of cell division and for the existence of osmotically growth-dependent staphylococci.

Cell Division↗
PubMed2000

Screening method for detecting staphylococci with reduced susceptibility to teicoplanin.

The incidence of infections caused by staphylococci with decreased susceptibility to teicoplanin (MIC>/=8 microg/ml) is increasing, but the disk diffusion test has difficulty detecting this low level of resistance. In addition, detection is complicated because of the heterogeneous phenotypes for teicoplanin. In this study, we evaluated an agar screening method to detect staphylococci with decreased susceptibility to teicoplanin or heterogeneous resistance. First, to investigate the inoculum density and teicoplanin concentration of screening agar, we used 10(5) and 10(6) CFU/ml and Mueller-Hinton agars supplemented with 6 and 8 microg of teicoplanin/ml to test 39 genetically distinct staphylococcal strains (15 strains with teicoplanin MICs>/=8 microg/ml and 24 strains with teicoplanin MICs</=4 microg/ml). On the basis of the results obtained, a final inoculum of 10(6) CFU/spot and a teicoplanin concentration of 8 microg/ml were selected. By this screening method, all strains having teicoplanin MICs>/=8 microg/ml or showing heteroresistance could be detected. These findings indicate that the method can be used as a reliable screening method for detecting staphylococci with reduced susceptibility to teicoplanin.

Anti-Bacterial Agents↗
PubMed1999

Identification and characterization of quaternary ammonium compound resistant staphylococci from the food industry.

The distribution of known genes conferring resistance to quaternary ammonium compounds (QACs) among different species of staphylococci isolated from the food industry was investigated. Twenty-four isolates hosting one of the genes qacA/qacB, smr, qacG or qacH, were subjected to species identification. Species determination was performed by biochemical analyses (API STAPH), comparative 16S rDNA sequence analysis and tDNA intergenic spacer length polymorphism analysis. Good correlation was obtained between the different methods. The isolates belonged to six different species of coagulase-negative Staphylococcus. The most commonly found species were Staphylococcus epidermidis and Staphylococcus saprophyticus. The results also indicated the possible spread of specific isolates of staphylococci which may reflect the dominance of certain strains in environments were QACs are used on a regular basis. The isolates were further characterized by the resistance phenotype to antimicrobial agents including antibiotics and disinfectants. Resistance to ampicillin, penicillin G and dyes was prevalent in strains harbouring the qacA or qacB genes, features also common among clinical staphylococci containing qacA/qacB. One QAC resistant strain harbouring the smr gene showed resistance to ampicillin, penicillin, tetracycline, erythromycin and trimethoprim. No enterotoxin production was detected among the QAC resistant strains.

Benzalkonium Compounds↗
PubMed2003

[In vitro activity of the pristinamycin against the isolated staphylococci in the french hospitals in 1999-2000].

One thousand six hundred and fifty clinically significant, consecutive and non redundant strains of staphylococci, including 863 Staphylococcus aureus and 787 coagulase negative staphylococci (CNS), were isolated between October 1999 and March 2000 in 35 French hospital laboratories. Susceptibilities were determined in each center by a standard diffusion method according to the recommendations of CA-SFM. Strains with vancomycin zone size diameter <17 mm were sent to the central laboratory for MIC determination of vancomycin by agar dilution, as recommended by the CA-CSFM. Frequencies of resistance to oxacillin were 38.6% for S. aureus (MRSA), 54% for the CNS, all species and 62% for S. epidermidis, respectively. The antibiotics tested showed a good activity against strains of S. aureus susceptible to oxacillin, more than 95% of strains being susceptible except for erythromycin (82.6%). Against MRSA, vancomycin and prisitinamycin had the highest rates of susceptible strains, greater than 93% for the later antibiotic. More than 92% of strains of CNS susceptible or resistant to oxacillin were sensitive to pristinamycin. Pristinamycin displayed a good activity whether the strains were constitutively or inducibly resistant to MLS(B). It comes out from this in vitro study that the rate of resistance of staphylococci to pristinamycin remains weak and stable in France. Pristinamycin is a good alternative for oral treatment of staphylococcal infections.

Cross Infection↗
PubMed2000

In vitro activity of selected cephalosporins and erythromycin against staphylococci and pneumococci isolated at 38 North American medical centers participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998.

The SENTRY Antimicrobial Surveillance Program employs a worldwide network of hospitals to monitor the predominant bacterial and fungal pathogens and antimicrobial susceptibility patterns associated with nosocomial and community-acquired bloodstream, respiratory tract, wound, and urinary tract infections. The purpose of this analysis of SENTRY data is to extract information on the current North American susceptibility patterns of pneumococci and oxacillin-susceptible staphylococci from the comprehensive SENTRY program database. Clinical isolates were provided by 30 centers in the United States (grouped into five regions) and eight centers in Canada. Susceptibility testing was performed at a central reference laboratory using broth microdilution methods and interpretive criteria specified by the National Committee for Clinical Laboratory Standards. Of 34 530 North American bacterial isolates tested during 1997 and 1998, 565 (1.6%) were oxacillin-susceptible, coagulase-negative staphylococci (CoNS). Cefazolin, cefepime, and ceftriaxone all had excellent activity against these CoNS (97.3%-99. 3% susceptible), and 90.4% were susceptible to ceftazidime. A total of 4404 isolates (12.8%) were oxacillin-susceptible Staphylococcus aureus. Overall, 98.9% to 99.2% were susceptible to cefazolin, cefepime, and ceftriaxone; ceftazidime did not have acceptable activity against these S. aureus. Streptococcus pneumoniae accounted for 1665 (4.8%) of North American SENTRY isolates. A total of 1212 isolates (72.8%) were fully susceptible to penicillin (MIC </= 0.06 microg/ml), 250 (15%) were penicillin intermediate (MIC 0.12-1 microg/ml), and 203 (12.2%) were penicillin resistant (MIC >/= 2 microg/ml). The rate of penicillin susceptibility was highest in Canada, and lowest in the South Central and South East regions of the United States. Cefepime, cefuroxime, ceftazidime, and erythromycin all demonstrated excellent efficacy (94%-99.8% susceptibility) against fully penicillin-susceptible isolates of S. pneumoniae. Among pneumococci with intermediate penicillin resistance, 88% were susceptible to cefepime, 92% to cefotaxime, and only 14% to ceftazidime. None of the antimicrobial agents in this analysis demonstrated adequate activity against fully penicillin-resistant pneumococci. In summary, the fourth-generation cephalosporin, cefepime, demonstrated consistently excellent efficacy against oxacillin-susceptible staphylococci and most pneumococci, and remains an appropriate choice for empiric therapy of serious infections.

Anti-Bacterial Agents↗
PubMed2002

Validation of Vitek version 7.01 software for testing staphylococci against vancomycin.

We tested 143 isolates of staphylococci with vancomycin by the National Committee for Clinical Laboratory Standards broth microdilution (BMD) reference method and compared the results to those generated using the Vitek automated system (GPS-105 and GPS-107 cards and version 7.01 software). For ten isolates, the vancomycin MICs by BMD were 8 microg/ml. By Vitek, the vancomycin MICs ranged from 2 to 16 microg/ml. Vancomycin MICs of > or =32 microg/ml were reported for two additional isolates by Vitek; however, the MICs decreased to < or =0.5 microg/ml on retesting. By BMD, the vancomycin MICs for both isolates were 1 microg/ml. While the modal vancomycin MIC results by BMD for S. aureus and coagulase-negative staphylococci (CoNS) were both 1 microg/ml, Vitek results showed a mode of < or =0.5 microg/ml for S. aureus, and a mode of 2 microg/ml for CoNS. Vitek did not report vancomycin MICs of 1 or 4 microg/ml for any of the isolates tested. While the sensitivity of detecting staphylococci with reduced susceptibility to vancomycin appears to be improved with Vitek version 7.01 software, when compared to earlier software versions, laboratories may notice an overall shift in MIC data toward higher vancomycin MICs, although for the most part, this does not affect the categorical interpretations of the results.

Anti-Bacterial Agents↗
PubMed1998

Staphylococcus aureus and coagulase-negative staphylococci from blood stream infections: frequency of occurrence, antimicrobial susceptibility, and molecular (mecA) characterization of oxacillin resistance in the SCOPE program.

Staphylococci are major causes of nosocomial blood stream infection. The recently completed SCOPE Surveillance Program found that coagulase-negative staphylococci (CoNS) and Staphylococcus aureus were the first and second most common etiologic agents, respectively, causing nosocomial blood stream infection in the USA. The frequency of oxacillin resistance was 68% among 1553 strains of CoNS and 26% among 787 strains of S. aureus in this study. Extended susceptibility profiles were generated for a subset of 150 S. aureus and 300 CoNS against 16 antimicrobial agents. Oxacillin-susceptible strains of both CoNS and S. aureus were uniformly susceptible to beta-lactam agents with the exception of ampicillin and penicillin. Oxacillin-susceptible S. aureus were also highly susceptible to the fluoroquinolones, aminoglycosides, and trimethoprim/sulfamethoxazole. The oxacillin-susceptible CoNS were less susceptible to these agents, and only glycopeptides were reliably active against oxacillin-resistant strains. PCR detection of the mecA gene was used to scrutinize current NCCLS interpretive breakpoint MICs for determining susceptibility or resistance to oxacillin. We found complete concordance between the presence or absence of mecA and the NCCLS oxacillin interpretive breakpoint categories for S. aureus. In contrast, the NCCLS breakpoints for oxacillin significantly underestimate the degree of true oxacillin resistance among CoNS. Using the presence of mecA as the reference standard, we detected 15.7% false susceptibility to oxacillin using a MIC susceptible breakpoint concentration of < or = 2 micrograms/mL. Lowering the oxacillin MIC breakpoint to < or = 0.25 microgram/mL for CoNS would greatly improve the accuracy of the MIC test performance. We found that both the current oxacillin disk test and the 30-microgram ceftizoxime disk test functioned quite well in predicting those strains of CoNS that contain mecA. These studies have demonstrated both a high level of antimicrobial resistance among nosocomial blood stream isolates of staphylococci as well as significant problems with the current NCCLS breakpoints for oxacillin when testing CoNS.

Anti-Bacterial Agents↗
PubMed2002

[Staphylococci resistant to antibiotic therapy].

Increasing frequency in antibiotic resistance in Staphylococcus aureus is worrying. In this review, we briefly describe the mechanisms of resistance to antibiotics in staphylococci and we report the current incidence of antibiotic resistance in France. Methicillin-resistance is mostly confined to hospitals. However, spread of multiply resistant strains of staphylococci to the community is a putative threat. Strains with diminished susceptibility to glycopeptides are rare but possibly underestimated because of the in vitro difficulties to detect glycopeptide resistance. A continuous resistance survey is necessary. The problem of multiresistance is different for hospital and community staphylococci. The later strains still remain susceptible to many antibiotics, apart from some exceptions. By contrast, incidence of multiply resistance in hospitals remains high. After a recent decrease, incidence of oxacillin resistance seems to be stabilized. A new and recent feature is the great variety of resistance phenotypes which can be found in methicillin-resistant strains, in particular with gentamicin susceptibility.

Drug Resistance↗
PubMed1998

Bacteriologic evidence of infection caused by coagulase-negative staphylococci in total hip replacement.

Coagulase-negative staphylococci are important agents of infected hip arthroplasties, but sample contamination from the skin flora may confuse the diagnosis. Recovery of multiple identical strains has been regarded as indication of true infection. We have evaluated 29 total hip replacement operations with cultures positive for coagulase-negative staphylococci in a prospective study, 16 with > or = 3 isolates available for strain identity analysis. In 26 episodes, > or = 3 cultures were positive for coagulase-negative staphylococci, but only 19 of them had strong or intermediate clinical evidence of infection. Negative clinical evidence of infection coincided with the absence of a predominating strain according to plasmid profile analysis. A reliable identity analysis may help to rule out infection when multiple cultures are positive in patients who lack clinical evidence of infection.

Coagulase↗
PubMed2000

Rapid detection of methicillin resistance in staphylococci using a slide latex agglutination kit.

The slide latex agglutination test, MRSA-Screen, was compared with the mecA polymerase chain reaction (PCR) and traditional susceptibility test methods for the detection of methicillin resistance in Staphylococcus aureus and coagulase-negative staphylococci. The MRSA-Screen test detected the same number of methicillin-resistant S. aureus as the mecA PCR and the traditional susceptibility tests. It correctly identified all 21 methicillin-susceptible S. aureus as being sensitive. It also produced the same result as the mecA PCR in identifying a methicillin-resistant S. aureus among six isolates classified as borderline resistant by traditional susceptibility tests. The MRSA-Screen test and mecA PCR detected methicillin resistance in 10 and 15 of 17 methicillin-resistant coagulase-negative staphylococci, respectively. From these results, it is concluded that the MRSA-Screen is a very accurate, reliable and rapid method of detecting methicillin resistance in S. aureus and is suitable for use in clinical microbiology laboratories. Further study of its use in detecting methicillin resistance in coagulase-negative staphylococci is required.

Agglutination Tests↗
PubMed1994

Susceptibility to desferrioxamines and other chelators of coagulase-negative staphylococci.

A total of 233 staphylococci and micrococci belonging to 17 species were tested for their susceptibility to desferrioxamines B, G and E, respectively. Using an agar diffusion method on iron poor media, all of the S. epidermidis, 12 out of 22 S. hominis and 5 out of 22 S. capitis strains were susceptible to desferrioxamines. Among the S. capitis strains tested, two of them were susceptible to desferrioxamine E and resistant to desferrioxamines B and G. All other staphylococci and micrococci tested were resistant to desferrioxamines B, G and E. Different susceptibility to 5 mM ethylenediaminedi-(o-phenylacetic acid) as an artificial chelator demonstrated the existence of additional iron-supplying systems in staphylococci and micrococci.

Chelating Agents↗
PubMed1974

Staphylococci in swimming pool water.

During a period of five years 1192 water samples from swimming pools were examined for staphylococci and 338 for coliform organisms only. Eighty-nine different pools were sampled.Numbers of staphylococci, estimated by the membrane filtration technique did not bear any significant relation to either bathing load or concentration of free chlorine.Wide variation in the staphylococcal count was observed when different parts of a pool were sampled on the same occasion.The only practicable standard for pool samples in relation to staphylococci would appear to be that these organisms should be absent from 100 ml. water when the pool has been out of use during at least ten hours before sampling if filtration and chlorination are adequate.

Chlorine↗