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PubMed1990

Susceptibility to ciprofloxacin of nosocomial gram-negative bacteria and staphylococci isolated in the UK.

At the end of 1989 the Division of Hospital Infection of the Central Public Health Laboratory completed five years of continuous surveillance of ciprofloxacin susceptibility amongst strains of Staphylococcus aureus and Pseudomonas aeruginosa. The strains studied were referred from many different UK laboratories for epidemiological or other typing. Between 1987 and 1989, referred cultures of coagulase-negative staphylococci, Klebsiella spp. and Enterobacter spp. were also examined. In total, 25,728 cultures from 254 different laboratories were included in the study, and S. aureus was the most common species amongst the survey material. Resistance to non-quinolone antimicrobials was common amongst the isolates. Over the study period there has been a gradual decline in the percentage of cultures received that were fully susceptible to ciprofloxacin and an increase in the number of laboratories referring strains with resistance or reduced sensitivity. Full susceptibility of S. aureus to ciprofloxacin has declined from 99.6% of 8981 cultures isolated in the two years before launch to 92.8% of 1968 cultures isolated during 1989. Amongst the coagulase-negative staphylococci there has been a similar decline in susceptibility from 99.4% of 658 cultures examined in 1987 to 92.6% of 433 cultures studied in 1989. There was also a decrease in susceptibility of P. aeruginosa isolates to ciprofloxacin from 98.6% of 2579 cultures isolated in 1985 and 1986 to 86.3% of 1152 cultures examined during 1989. Most of this decrease was attributable to the appearance of strains of intermediate susceptibility to ciprofloxacin (MICs 2 or 4 mg/l). Virtually no resistance to ciprofloxacin was observed amongst isolates of Klebsiella spp. and Enterobacter spp. referred between 1987 and 1989. The emergence of ciprofloxacin resistance, and by implication cross resistance to many of the other fluoroquinolones, is a worrying development and suggests that caution should be exerted in the use of these compounds for the treatment of infections due to staphylococci and P. aeruginosa.

Ciprofloxacin↗
PubMed2003

Prevalence and mechanisms of low- and high-level mupirocin resistance in staphylococci isolated from a Korean hospital.

Mupirocin has been used against Gram-positive pathogenic bacteria, and is a specific inhibitor of bacterial isoleucyl-tRNA synthetase. In this work, we have determined the prevalence of mupirocin resistance among staphylococci isolated from a Korean hospital, and have investigated the characteristics of the resistance. In Staphylococcus aureus, the prevalence of high-level mupirocin resistance was 5% (16 of 319), whereas low-level mupirocin resistance was not detected. In coagulase-negative staphylococci (CoNS) the rates of high- and low-level mupirocin resistance were 16.7% (34 of 204) and 10.3% (21 of 204), respectively. The high-level resistant strains contained the ileS-2 gene, which encodes a novel staphylococcal isoleucyl-tRNA synthetase. In contrast, all of the low-level mupirocin-resistant CoNS contained the mutation V588F, which is located near the conserved motif KMSKS, within the chromosomal staphylococcal isoleucyl-tRNA synthetase gene (ileS). In conclusion, this work describes the recent, but rapid, emergence of two different types of mupirocin-resistant staphylococci in Korea, and the sequence and mutant characterization of the isoleucyl-tRNA synthetase of CoNS.

Cross Infection↗
PubMed2006

Diversity and evolution of blaZ from Staphylococcus aureus and coagulase-negative staphylococci.

OBJECTIVES: To elucidate the diversity and evolutionary history of plasmid- and chromosomally-located blaZ, to detect indications of frequent exchange of blaZ between human and bovine staphylococci and to estimate the frequency of transfer of blaZ between coagulase-negative staphylococci (CoNS) and Staphylococcus aureus of bovine origin. METHODS: blaZ was detected in 143 strains of penicillin-resistant S. aureus and CoNS from five Danish cattle herds (n = 25/23), random CoNS isolates from Denmark (n = 37), a collection of S. aureus from six different countries (n = 52), humans in Denmark (n = 3) and beta-lactamase control strains (n = 3). The sequence was determined in 105 strains and compared to published sequences by pairwise and multiple alignments. Maximum likelihood analysis was performed including bootstrap analysis. Parsimony, neighbour joining and consensus comparisons were performed for recombination. The localization of blaZ was determined by Southern blotting in 108 isolates. RESULTS: All penicillin-resistant strains carried blaZ and showed a similar organization of blaR1 and blaZ. The blaZ gene was localized to a plasmid in only 16 of the resistant strains. Sixty-nine sequences representing 105 isolates and sequences retrieved from public databases were compared. A phylogenetic tree showed that blaZ exists in three evolutionary lines: one group was of plasmid origin, one group was of chromosomal origin and one intermediate group. Sixty-nine sequence types were demonstrated. They translated into 11 BlaZ protein types. The major types all contained strains of both human and bovine origin, and more than one Staphylococcus species, demonstrating a shared gene pool. In a comparison of S. aureus and CoNS obtained from five Danish cattle herds, the same type of blaZ was only detected in one case. CONCLUSIONS: Results indicated a separate evolution for plasmid- and chromosomally-encoded blaZ. Although a common gene pool seems to exist among staphylococci, exchange of blaZ between strains and species is judged to be an extremely rare event.

Alleles↗
PubMedDate not supplied

Septicemia due to coagulase-negative staphylococci in a neonatal intensive care unit: clinical and bacteriological features and contaminated parenteral fluids as a source of sepsis.

During the years 1979 to 1981 we experienced an increasing incidence of septicemia due to coagulase-negative staphylococci in the neonatal intensive care unit (NICU). A detailed analysis was performed for the 1981 NICU population. More than 90% of cases occurred in premature infants of low birth weight (less than 2500 g). All septicemic infants were receiving intravenous therapy and total parenteral nutrition (TPN) solutions had been administered to nearly 80% just before or during the septic episode. A case-control study performed for the 1981 NICU population, which included 26 proved cases of coagulase-negative staphylococcal septicemia and 26 matched controls, did not uncover any differences in underlying diseases or modes of treatment between cases and controls. However, the infusion of contaminated TPN fluids was identified as a significant risk factor. Random bacteriological checks of TPN fluids revealed that nearly 20% of these solutions were contaminated, mainly with coagulase-negative staphylococci. The incidence of staphylococcal septicemia in infants who had received contaminated TPN fluids was 10-fold higher than in infants who had received sterile solutions (P less than 0.0005). The majority of coagulase-negative staphylococci isolated from the blood cultures from the NICU were multiply resistant to antibiotics although all isolates were susceptible to cephalothin. Treatment, consisting of removal or replacement of the intravenous devices and the administration of cephalothin and fresh plasma, was universally successful.

Humans↗
PubMed1983

Effect of low intraphagolysosomal pH on antimicrobial activity of antibiotics against ingested staphylococci.

The ability of aminoglycoside antibiotics and rifampicin to kill Staphylococcus aureus that had been ingested by blood polymorphonuclear leukocytes (PMNs) in vitro was investigated. Gentamicin and streptomycin failed to kill intracellular staphylococci, possibly because they could not penetrate PMNs or were inactivated by the low intraphagolysosomal pH. Rifampicin accumulated within the leukocytes in a form that killed staphylococci in a cell-free medium, but the bactericidal activity of intracellular rifampicin against ingested staphylococci was much less than that in a cell-free system. Investigations with granules isolated from PMNs, at various pH-values, revealed that the impairment of rifampicin activity was a result of limitation of the staphylococcal growth rate by a low pH. These observations indicate that the inhibition of intraphagocytic bacterial growth by the low intraphagolysosomal pH and other phagolysosomal bacteristatic factors determines the antimicrobial activity of accumulated antibiotics.

Animals↗
PubMed1986

A simplified system for the identification of staphylococci by multipoint inoculation of test media.

Most hospital bacteriologists have divided staphylococci into two groups: Staphylococcus aureus and the coagulase-negative staphylococci of which the novobiocin-resistant varieties are termed S. saprophyticus. The identification of S. aureus has been easy but that of the other staphylococci has provided some difficulties and most currently available methods are expensive or time consuming. Multipoint inoculation of a set of test media provides a convenient way of identifying large numbers of staphylococcal isolates. In tests with 118 isolates, mainly clinical but including some environmental isolates and some from the National Collection of Type Cultures, there was 90.7% agreement between identifications by the API-Staph system and by the multipoint system. The remaining 9.3% of strains was identified by the multipoint system but could not be identified by use of the data supplied in the API-Staph kit.

Bacteriological Techniques↗
PubMed1988

Trimethoprim resistance determinants encoding a dihydrofolate reductase in clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci.

The molecular and biochemical basis of resistance to high concentrations (MIC greater than or equal to 1000 mg/L) of trimethoprim (Tpr(H] was examined in Australian isolates of Staphylococcus aureus and coagulase-negative staphylococci. The Tpr(H) determinant (dfr A) was located within a 2.75-Kb Bg/II fragment on the S. aureus aminoglycoside-resistance plasmids pSK1 and pSK16 as judged by comparative restriction mapping with two naturally-occurring variants, pSK9 and pSK14, which did not encode trimethoprim resistance. This was confirmed in DNA-DNA hybridisation experiments in which a 0.9-Kb sequence of pSK1 DNA was used as a specific probe for the Tpr(H) gene. Plasmid DNA from three strains of coagulase-negative staphylococci, and the chromosomal material of one other isolate, were found to share homology with the probe DNA. Dihydrofolate reductases produced by these strains were virtually identical to the type S1 enzyme encoded by the S. aureus plasmid pSK1. Interspecies transfer may have been responsible for the conservation of Tpr(H) gene sequences among staphylococci.

Chromosome Mapping↗
PubMed1981

Interactions between dermatophyte fungi and staphylococci or Brevibacterium in vitro.

Interactions between dermatophyte fungi and staphylococci or brevibacteria on a new skin-based culture medium are described. Penicillin production by the fungus selects penicillin resistant S. aureus or B. epidermidis. Fungi are inhibited by brevibacteria but not by the staphylococci. "Keratolysis" by fungi may contribute to the growth nutrients of staphylococci.

Arthrodermataceae↗
PubMed1998

Coagulase-negative staphylococci isolated from various skin lesions.

We isolated 162 coagulase-negative staphylococci (48: from infection, 114: from colonization) from various skin diseases between January, 1995, and January, 1998. From eighteen infected cysts, 10 Staphylococcus epidermidis strains, 3 S. capitis strains, 2 S. hominis strains, 2 S. auricularis strains, and one S. saprophyticus strain were individually detected. Similarly, from ten folliculitis lesions, 6 S. epidermidis strains, 2 S. capitis strains, and 2 S. hominis strains, and from five furuncle lesions, 3 S. lugdunensis strains, one S. epidermidis strains, and one S. hominis strain were detected, respectively. Four abscesses with mild inflammatory signs were localized on the scalp; S. epidermidis strains alone were detected from them. From two felons, one S. lugdunensis strain and one S. haemolyticus strain were detected, respectively. Staphylococcus epidermidis and S. lugdunensis strains seems to be more frequently associated with skin suppurative lesions than other strains. Staphylococcus hominis strains and S. capitis strains were suggested to be potential pathogens in the initiation of suppuration in various purulent skin lesions. Among the 28 S. epidermidis strains, 13 (46.4%) were methicillin-resistant (oxacillin, minimum inhibitory concentration > or = 4 micrograms/ml). Twelve (29.3%) out of the other 41 coagulase-negative staphylococci were methicillin-resistant. Coagulase-positive and -negative staphylococci showed no differences in susceptibility tests against various antistaphylococcal agents.

Anti-Bacterial Agents↗
PubMed2006

The human anionic antimicrobial peptide dermcidin induces proteolytic defence mechanisms in staphylococci.

Antimicrobial peptides (AMPs) represent a key component of innate host defence against bacterial pathogens. Bacterial resistance mechanisms usually depend on the characteristic positive charge of AMPs. However, several human cell types also produce anionic AMPs, mechanisms of resistance to which are poorly understood. Here we demonstrate that the skin commensal and leading nosocomial pathogen Staphylococcus epidermidis senses and efficiently inactivates the anionic AMP dermcidin. Dermcidin induced differential expression of global regulatory systems, leading to increased expression of proteases with the capacity to degrade dermcidin, particularly S. epidermidis SepA. A similar induction of extracellular proteolytic activity was found in Staphylococcus aureus, suggesting a common regulatory mechanism in staphylococci. Notably, human cationic AMPs also led to the activation of global regulators, but inactivation of dermcidin by SepA was much more effective than of the tested cationic peptides. The ability to react to the unusual, anionic dermcidin with effective countermeasures likely contributes to the extraordinary success of staphylococci as colonizers and infective agents on human epithelia. Our study indicates that staphylococci can react to human AMPs by specific mechanisms of resistance and establishes a crucial role for staphylococcal proteases in the interaction with human innate host defence.

Adaptation, Physiological↗
PubMed1976

Binding of IgA to protein-A-containing staphylococci: relationship to subclasses.

Among 54 human monoclonal IgA proteins, 5 inhibited the binding of labeled human monoclonal IgM (IgM Se and IgM Ba) to protein-A-containing staphylococci, whereas 48 did not have this ability. One protein (IgA Ha) showed discordant findings in the IgM Se and IgM Ba inhibitions assays. Among the 54 IgA proteins, 49 were of the IgA1 and 5 of the IgA2 subclass. All of the 5 IgA2 proteins inhibited the binding of IgM Se and IgM Ba to staphylococci, whereas the 48 proteins that reacted negatively in the two inhibition assays belonged to the IgA1 subclass. These findings show that the ability to react with staphylococci is a property of the IgA2 subclass. IgM proteins may also be divided into two groups based on different reactivities with protein A. It is proposed to call the two IgM subclasses IgM1 and IgM2, where the latter is defined by ability to react with protein A.

Bacterial Proteins↗
PubMed1995

Occurrence of enteric rods, staphylococci and Candida in subgingival samples.

The frequency and percentage of enteric rods, staphylococci and Candida were determined in 973 subgingival samples collected from 535 patients subjected to different periodontal treatment procedures. The analysis was performed with culture technique using selective and nonselective media. One or more organisms were detected in 65.5% of the samples and in 76.7% of the patients. In most samples enteric rods, staphylococci and/or Candida constituted a small amount of the total microbial viable count. Enteric rods exceeded 10% of the total viable count in 30 samples. Staphylococci occurred in more than 10% in only 3 samples. In these 3 samples, enterics constituted more than 10% of the total viable count. Candida was not found to exceed 10% of the total viable count in any of the samples. No statistically significant correlation was found between the presence of any of the target microorganisms and kind of periodontal treatment procedure received, antibiotic administration or sample transport time.

Adolescent↗
PubMed2005

Effects of a topical essential oil-containing formulation on biofilm-forming coagulase-negative staphylococci.

AIMS: To evaluate the antimicrobial effects of Polytoxinol (PT), a topical essential oil-based formulation, against biofilm positive strains of coagulase-negative staphylococci. METHODS AND RESULTS: Using a microtitre plate assay we measured inhibitory effects for PT against a selection of biofilm-forming clinical isolates of coagulase-negative staphylococci. Susceptibility varied considerably (MIC = 0.6-20 000 ppm). For the most tolerant clinical isolate (Staphylococcus warneri) biofilm growth was inhibited by a 32-fold lower PT concentration than planktonic growth. This inhibition of biofilm development, which was not observed with the other test isolates, was related to an inhibition of the initial phase of S. warneri cell adherence to the polystyrene surface. CONCLUSION: The antimicrobial efficacy of PT was verified against clinical isolates of coagulase-negative staphylococci in vitro. PT was able to inhibit biofilm formation in the most tolerant isolate at sub-inhibitory concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: These observations indicate that an ability to prevent biofilm formation, independently of effects on cell viability may contribute to the in vivo topical efficacy of essential oils.

Anti-Infective Agents, Local↗
PubMed1989

Septicaemia with coagulase negative staphylococci in a neonatal intensive care unit. Risk factors for infection, and antimicrobial susceptibility of the bacterial strains.

Septicaemia caused by coagulase negative staphylococci is a problem in the neonatal intensive care units (NICU). The very low birthweight (VLBW) infants are at a special high risk because of their immature host defense. In this study the potential risk factors were compared between the VLBW septicaemia patients and the VLBW infants who had not contracted septicaemia in the NICU. The factor most clearly related with septicaemia was the use of umbilical artery catheters. The strategy against neonatal septicaemia includes restriction of the use of intravascular catheters. Also enhancement of the host defense by immunoglobulin therapy is considered. The coagulase negative staphylococci were multiresistant to antibiotics. The combination of netilmicin and benzylpenicillin covered the bacteria found in septicaemia cases in the NICU, and is now the standard treatment in suspected cases. Coagulase negative staphylococci are treated with vancomycin or netilmicin.

Anti-Bacterial Agents↗
PubMed1977

Classification of coagulase-negative staphylococci in the diagnostic laboratory.

One hundred and ninety-eight coagulase-negative staphylococci isolated from urines, blood cultures, and pus samples were classified by means of two identification schemes, and their wall teichoic acids were determined serologically. S. epidermidis, S. saprophyticus, and S. cohnii were identified reliably by the use of five criteria: acid aerobically from sucrose, trehalose, and mannitol, phosphatase production, and sensitivity to novobiocin. Further species, notably S. haemolyticus and S. hominis, could be identified when haemolysis on blood agar plates was included in the criteria group. The investigation shows, that a considerable number of coagulase-negative staphylococci isolated from human specimens belong to species other than S. epidermidis and S. saprophyticus. These staphylococci can cause human infections and should be identified in the diagnostic laboratory. S. epidermidis and S. saprophyticus were found to contain the teichoic acids previously identified in these species. S. cohnii contained the same teichoic acids as S. saprophyticus. No characteristic teichoic acid was demonstrated in the other species, but several strains contained poly C (beta-N-acetylglucosaminylglycerol teichoic acid).

Bacteriological Techniques↗
PubMed1977

On the diagnosis of coagulase-negative staphylococci with emphasis on Staphylococcus saprophyticus.

This study concerns the diagnosis of coagulase-negative staphylococci, with special emphasis on novobiocin-resistant species, vis S. saprophyticus, S. cohnii and S. xylosus. Disc diffusion tests for novobiocin were found useful in the differential diagnosis of coagulase-negative staphylococci isolated from urine specimens, but not from pus and blood cultures. We report on the resistance of S. saprophyticus to nalidixic acid and the use of this characteristic in the diagnosis of coagulase-negative staphylococci known to be novobiocin-sensitive, but which have subsequently acquired resistance to novobiocin. The results of different tests for betalactamase production in S. saprophyticus are presented. "Clover leaf" tests suggested such a production in about half of the strains studied, while no strain produced betalactamase as indicated by tests using chromogenic cephalosporin or benzylpenicillin in capillary tube tests. -The failure of tests for nitrate reduction, glucose consumption and of cultrues of urine on MacConkey's agar in the diagnosis of urinary tract infections caused by S. saprophyticus, is documented. The concept "significant bacteriuria" in the diagnosis of S. saprophyticus infections of the urinary tract above the bladder neck is also considered.

Bacteriological Techniques↗
PubMed1992

Enterotoxin and toxic shock syndrome toxin-one production by staphylococci isolated from mastitis in sheep.

From 160 staphylococci isolated from ovine mastitis, 125 were identified as coagulase-positive staphylococci (CPS) and 35 as coagulase-negative staphylococci (CNS). Of these, 108 (87.8%) S. aureus produced at least one of the staphylococcal enterotoxins (SE) described. However, no CNS was found to be enterotoxigenic. Enterotoxin C (SEC) was the type most frequently produced. TSST-1 was shown to be produced by 91 (74.0%) of S. aureus, almost invariably in combination with SEC. Three CNS strains were also found to produce TSST-1 (two strains of S. xylosus and one strain of S. epidermidis).

Animals↗
PubMed1995

Evaluation of staphylococci isolated from a blood culture system (Colorbact).

During a one-year period, all blood cultures positive for staphylococci from two of the smaller Danish counties with non-university hospitals only were evaluated. The isolates were speciated and coagulase-negative staphylococci (CoNS) were biotyped. Furthermore, antibiogram, phage typing and lectin typing were performed for all isolates. Clinical information was obtained by telephone, and before any bacteriological identification was performed, a preliminary judgment was made as to whether the positive blood culture was of clinical significance. A total of 3,500 blood cultures were evaluated and 426 (12.2%) were positive. One hundred and sixty blood cultures from 137 patients contained staphylococci; 36 of these patients had a pure culture of Staphylococcus aureus. One hundred and twenty-four CoNS were found and identified as S. epidermidis (81), S. hominis (19), S. haemolyticus (8), S. simulans (1), and Micrococcus species (3), and another 12 staphylococcal isolates which could not be identified to species level. A total of 35 patients had mixed cultures, including 6 with S. aureus as one of the isolates and 15 with mixed CoNS. Clinical relevance was estimated in 90% of cases where the later bacterial identification showed S. aureus, whereas clinical relevance was absent in the majority of cases including CoNS. Methicillin and gentamicin resistance was absent among S. aureus, but frequent among CoNS, especially S. epidermidis, where 40% were resistant to methicillin and 30% to gentamicin.

Bacteremia↗