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PubMed1969

Some properties of the beta-lactamase genes in Staphylococcus epidermidis.

Eighty-three per cent of 200 different freshly isolated cultures of Staphylococcus epidermidis produced beta lactamase. Growth in the presence of acridine orange or ethidium bromide or growth at 44 C resulted in a high frequency of loss of the beta lactamase genes in some strains of S. epidermidis. The relationship between beta-lactamase production and resistance to mercuric, cadmium and arsenate ions differed from that observed in Staphylococcus aureus. It is postulated that the genes for beta lactamase in certain strains of S. epidermidis are on a plasmid.

Acridines↗

PubMed1971

Nuclease production and lysostaphin susceptibility of Staphylococcus aureus and other catalase-positive cocci.

Some strains of Staphylococcus epidermidis and Micrococcus sp. produce nucleases. However, thermal stability was shown to be unique to the nucleases of S. aureus. In addition, two micromethods for susceptibility testing to lysostaphin were more precise and convenient than anaerobic glucose fermentation in distinguishing between the genera Staphylococcus and Micrococcus.

Anti-Bacterial Agents↗

PubMed1973

Significance of Staphylococcus epidermidis in the clinical laboratory.

Susceptibility to 11 antibiotics was determined for 63 cultures of Staphylococcus aureus and 63 cultures of Staphylococcus epidermidis obtained at random from the clinical laboratory. The incidence of resistance to nine of these antibiotics was greater for S. epidermidis than for S. aureus. Studies of the minimal inhibitory concentration of these cultures to clindamycin showed that 61 cultures of S. aureus were susceptible whereas only 46 cultures of S. epidermidis were susceptible to this antibiotic. Although cultures of S. aureus were more active in the production of seven virulence factors, some cultures of S. epidermidis produced virulence factors. By successive cultivation in increasing concentrations of clindamycin, resistant variants were obtained for 10 cultures of S. aureus and 3 cultures of S. epidermidis. The presence of subinhibitory concentrations of clindamycin inhibited the production of some virulence factors by the resistant variants. In view of the greater resistance of S. epidermidis to antibiotics and its ability to produce virulence factors, its isolation in the clinical laboratory should not be regarded lightly.

Anti-Bacterial Agents↗

PubMed1975

Distribution and persistence of Staphylococcus and Micrococcus species and other aerobic bacteria on human skin.

The districution of Staphylococcus and Micrococcus species and associated coryneform bacteria, Acinetobacter, Klebsiella, Enterobacter, Bacillus, and Streptomyces on skin was determined during October 1971 from samples collected on persons living in North Carolina and New Jersey. Persistence of these organisms on skin was estimated in temporal studies conducted during the period from June 1971 to June 1972 on persons living in North Carolina. Staphylococci and coryneforms were the most predominant and persistent bacteria isolated from the nares and axillae. Staphylococci, coryneforms, micrococci, and Bacillus were the most predominant and persistent bacteria isolated from the head, legs, and arms. Acinetobacters were most frequently isolated during the warmer months of the years. Staphylococcus aureus and S. epidermidis were the most predominant and persistent staphylococci isolated from the nares, whereas S. epidermidis and S. hominis were the most predominant and persistent staphylocicci isolated from the axillae, head, legs, and arms. S. capitis was often isolated from the head and arms and S. haemolyticus was often isolated from the head, legs, and arms. S. simulans, S. xylosus, S. cohnii, S. saprophyticus, S. warneri, and an unclassified coagulase-positive species were only occasionally isolated from skin. Micrococcus luteus was the most predominant and persistent Micrococcus isolated from skin and preferred regions of the head, legs, and arms. M. varians was the second most frequent Micrococcus isolated. M. lylae, M. sedentarius, M. roseus, M. kristinae, and M. nishinomiyaensis were only occasionally isolated from skin. M. lylae was most frequently isolated during the colder months of the years.

Acinetobacter↗

PubMed2026

First UK use of bacteriophage therapy with DAIR for chronic Staphylococcus aureus prosthetic joint infection.

BACKGROUND: Chronic Staphylococcus aureus prosthetic joint infection (PJI) remains difficult to manage when surgical revision and long-term antibiotics are not feasible. Bacteriophage therapy is emerging as a potential adjunct, though experience in orthopedic infections, particularly in the United Kingdom, is limited. CASE SUMMARY: We report the first UK case of intra-articular bacteriophage therapy administered alongside debridement, antibiotics, and implant retention (DAIR) for chronic methicillin-sensitive Staphylococcus aureus knee PJI. An 81-year-old man with multiple comorbidities developed persistent infection following revision knee arthroplasty, with recurrent sinus formation despite multiple surgical washouts and prolonged suppressive antibiotics. Major revision surgery and amputation were not viable options. Following a multidisciplinary review through the UK Clinical Phage Network, targeted phage therapy was pursued as salvage treatment. Phage susceptibility testing identified an active lytic phage (ISP). The patient underwent open DAIR with intra-articular phage administration, adjunctive local antibiotics, short-course intravenous antimicrobials, and subsequent oral suppressive therapy. Two further intra-articular phage doses were administered postoperatively. Initial sinus closure occurred, but recurrence developed within 4 weeks. At 18 months, symptoms were partially improved with better mobility and reduced inflammation, though one sinus tract persisted. No significant adverse effects were observed. Whole-genome sequencing of pretreatment isolates demonstrated a predominantly ST5 S. aureus genotype with conserved biofilm-associated virulence genes and limited antimicrobial resistance in addition to clonal diversification consistent with chronic biofilm infection. CONCLUSION: This case demonstrates the feasibility and safety of intra-articular phage therapy during DAIR in a UK setting but highlights biological, logistical, and pharmacological factors that may limit efficacy in advanced chronic PJI.

Staphylococcus aureus↗

PubMed2006

Comparative antibody-mediated phagocytosis of Staphylococcus epidermidis cells grown in a biofilm or in the planktonic state.

Staphylococcus epidermidis is an important cause of nosocomial infections. Virulence is attributable to elaboration of biofilms on medical surfaces that protect the organisms from immune system clearance. Even though leukocytes can penetrate biofilms, they fail to phagocytose and kill bacteria. The properties that make biofilm bacteria resistant to the immune system are not well characterized. In order to better understand the mechanisms of resistance of bacteria in biofilms to the immune system, we evaluated antibody penetration throughout the biofilm and antibody-mediated phagocytic killing of planktonic versus biofilm cells of S. epidermidis by using a rabbit antibody to poly-N-acetylglucosamine (PNAG). These antibodies are opsonic and protect against infection with planktonic cells of PNAG-positive Staphylococcus aureus and S. epidermidis. Antibody to PNAG readily penetrated the biofilm and bound to the same areas in the biofilm as did wheat germ agglutinin, a lectin known to bind to components of staphylococcal biofilms. However, biofilm cells were more resistant to opsonic killing than their planktonic counterparts in spite of producing more PNAG per cell than planktonic cells. Biofilm extracts inhibited opsonic killing mediated by antibody to PNAG, suggesting that the PNAG antigen within the biofilm matrix prevents antibody binding close to the bacterial cell surface, which is needed for efficient opsonic killing. Increased resistance of biofilm cells to opsonic killing mediated by an otherwise protective antibody was due not to a biofilm-specific phenotype but rather to high levels of antigen within the biofilm that prevented bacterial opsonization by the antibody.

Animals↗

PubMed2006

The yjeQ gene is required for virulence of Staphylococcus aureus.

Gene products required for in vivo growth and survival of Staphylococcus aureus and other pathogens represent new targets for antimicrobial chemotherapy. In this study we created a Staphylococcus aureus yjeQ deletion strain and tested its virulence using a mouse kidney abscess infection model. The yjeQ deletion strain was compromised for growth in vitro and severely attenuated for virulence. We concluded that yjeQ is an attractive and novel new drug target.

Abscess↗

PubMed2006

Isolation and characterization of biofilm formation-defective mutants of Staphylococcus aureus.

Staphylococcus aureus produces biofilm and this mode of colonization facilitates infections that are often difficult to treat and engender high morbidity and mortality. We have exploited bacteriophage Mu transposition methods to create an insertional mutant library in a highly biofilm-forming S. aureus clinical isolate. Our screen identified 38 insertions in 23 distinct genes together with one intergenic region that significantly reduced biofilm formation. Nineteen insertions were mapped in loci not previously known to affect biofilm in this organism. These include insertions in codY, srrA, mgrA, and fmtA, a putative DEAD-box helicase, two members of the zinc-metallo-beta lactamase/beta-CASP family, and a hypothetical protein with a GGDEF motif. Fifteen insertions occurred in the icaADBC operon, which produces intercellular adhesion antigen (PIA) and is important for biofilm formation in many strains of S. aureus and Staphylococcus epidermidis. Obtaining a high proportion of independent Em-Mu disruptions in icaADBC demonstrated both the importance of PIA for biofilm formation in this clinical strain and the strong validation of the screening procedure that concomitantly uncovered additional mutants. All non-ica mutants were further analyzed by immunoblotting and biochemical fractionation for perturbation of PIA and wall teichoic acid. PIA levels were diminished in the majority of non-ica insertional mutants. Three mutant strains were chosen and were functionally complemented for restored biofilm formation by transformation with plasmids carrying the cloned wild-type gene under the control of a xylose-inducible promoter. This is a comprehensive collection of biofilm-defective mutants that underscores the multifactorial genetic program underlying the establishment of biofilm in this insidious pathogen.

Biofilms↗

PubMed1974

Biological properties of the encapsulated Staphylococcus aureus M.

Strain M, classified as a Staphylococcus aureus, behaves like the other rare encapsulated staphylococcal strains. It was clumping-factor negative, grew in diffuse-type colonies in serum-soft agar, and produced rapidly fatal disease in mice. Strain M was highly resistant to phagocytosis by human or mouse leukocytes and required both specific antibody and heat-labile serum factor(s) for efficient ingestion by human polymorphonuclear leukocytes. Electron micrographs confirmed the presence of a large capsule. Agglutination studies, active or passive mouse protection experiments, and opsonic studies revealed that strain M represents a new, immunologically distinct strain of encapsulated staphylococcus. Strain M differs from other known encapsulated staphylococci in several other respects: its cellular and colonial morphology is atypical; its LD(50) in the mouse peritoneal model is 100 times less than that of other mouse lethal strains; it is poorly opsonized by normal human serum; and, finally, it possesses an unusually large capsule as seen in electron micrographs.

Agglutination Tests↗

PubMed1975

Phagocytosis and intracellular killing of Staphylococcus aureus by normal mouse peritoneal macrophages.

Although Staphylococcus aureus is incapable of intracellular multiplication in cultured mouse peritoneal macrophages, it is killed at a much slower rate than the avirulent Staphylococcus epidermidis. In addition to the presence of capsular material which inhibits phagocytosis of specific strains of S. aureus, the data show that a number of cellular and environmental factors affect the functional capacities of mononuclear phagocytic cells. The data obtained by varying the initial level of infection indicate that the number of ingested bacteria may subsequently alter the kinetics of intracellular killing. In vitro maturation of macrophages in culture was also found to exert a pronounced effect on the kinetics of bacterial death.

Animals↗

PubMed1976

Synergistic effect on mortality in mice with murine cytomegalovirus and Pseudomonas aeruginosa, Staphylococcus aureus, or Candida albicans infections.

A synergistic effect on mortality was demonstrated in a combined infection of mice with murine cytomegalovirus (MCMV) and Pseudomonas aeruginosa, Staphylococcus aureus, or Candida albicans. Mice infected intraperitoneally with a 0 to 20% lethal dose inoculum of MCMV 3 days prior to the intravenous injection of a 0 to 20% lethal dose inoculum of either the bacteria or fungus demonstrated a striking enhancement of mortality. MCMV-infected mice given Pseudomonas or Staphylococcus exhibited a 90 to 100% mortality within 24 to 48 h, whereas 80% of viral-infected animals injected with Candida died in 5 days. Injection of the bacteria or fungus at various times during the MCMV infection resulted in enhanced mortality on days 0,1,2, and 3 of the viral infection. Greatest synergism was observed on day 3, with a progressive decline in death rates thereafter. Immunization with MCMV abrogated the synergistic effect on mortality in all three combined infections. Immunization with Pseudomonas reduced mortality in the combined MCMV-Pseudomonas infection. These results indicate that mice exhibit a markedly enhanced susceptibility to bacterial and fungal infections during the course of the MCMV infection and suggest that the enhancement may be related to viral-induced alterations in host resistance.

Animals↗

PubMed1982

Morphological examination of the glycocalyces of Staphylococcus aureus strains Wiley and Smith.

The glycocalyces of gram-positive bacteria have only been studied to a limited extent, with most studies being directed at the elucidation of capsules. With modern methods of electron microscopy, it has been shown that an extensive, diffuse polyanionic matrix surrounds Staphylococcus aureus cells of the Smith and Wiley strains, both in vivo and in modified staphylococcus 110 media. This slime layer was extracapsular in the case of the Smith strain, yet appeared to be the only layer peripheral to the teichoic acid in the Wiley strain. It is proposed that these glycocalyces serve a protective function and that their production is induced not only by excess nutrients in the growth medium but also by metabolic stress.

Culture Media↗

PubMed1983

Production, purification, and properties of a bacteriocin from Staphylococcus aureus isolated from saliva.

Staphylococci from samples of human saliva were isolated on staphylococcal-selective agar plates. These strains were tested for the inhibition of the growth of Staphylococcus aureus FDA209P. The frequency of inhibitory strains among all of the staphylococcal isolates was 5.2%. Strain IYS2, which formed the biggest inhibitory zone against the growth of the indicator strain, was used as the producer of bacteriocin. IYS2 was identified to be S. aureus, based on its biological properties. The bacteriocin was purified by sequential procedures, including ammonium sulfate precipitation, fractionation with ethanol, ion-exchange chromatography, and gel filtration. Its molecular weight was determined to be 5,000. The isoelectric point was 10.0. In amino acid composition, lysine, histidine, aspartic acid, valine, and phenylalanine were predominant. The bacteriocin was heat stable but inactivated by proteases or peptidase. The bacteriocin had a bactericidal effect on susceptible cells. An analysis of the inhibitory spectrum among typical oral indigenous bacteria showed that Streptococcus salivarius, Propionibacterium acnes, Corynebacterium parvulum, and Actinomyces israelii were susceptible to the bacteriocin. Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, Actinomyces viscosus, Actinomyces naeslundii, Fusobacterium nucleatum, Bacterionema matruchotii, and Bacteroides melaninogenicus were resistant. The majority of S. aureus tested were susceptible, and all Staphylococcus epidermidis strains tested were resistant.

Amino Acids↗

PubMed1983

Role of granulocytes and monocytes in experimental Staphylococcus epidermidis endocarditis.

The role of granulocytes and monocytes during the induction and course of Staphylococcus epidermidis endocarditis was investigated by the selective depletion of monocytes with the drug VP16-213 and of both granulocytes and monocytes with nitrogen mustard. The induction of endocarditis was influenced only by the depletion of monocytes: the 50% infective dose differed significantly, being 3.4 X 10(5) CFU in control rabbits and 3.4 X 10(4) CFU in the monocyte-depleted rabbits, whereas no significant differences were found between the latter and those depleted of both granulocytes and monocytes. Also, control rabbits injected with 10(6) or 10(7) CFU had a significantly higher incidence of sterile vegetations than did rabbits selectively depleted of granulocytes or monocytes. Compared with baseline values, mean monocyte numbers at the time of bacterial inoculation were significantly increased in control rabbits whose vegetations remained sterile, whereas this effect was not seen in rabbits whose vegetations became infected. The course of the endocarditis appeared to be significantly influenced by both granulocytes and monocytes. Comparison showed that a decrease of the same numbers of these cells per microliter of blood was accompanied for the monocytes by an approximately fourfold higher increase of the number of staphylococci in the vegetations. The correlation between the number of granulocytes and of monocytes on the one hand and the number of staphylococci in the vegetations on the other was not substantially influenced by the duration of the disease or the number of staphylococci injected to induce the endocarditis. The number injected proved to be significantly correlated with the number of staphylococci in the vegetations. In rabbits with numbers of CFU per gram of vegetation exceeding 10(7), blood cultures were usually positive. This finding applied rarely to control rabbits, but generally to drug-treated rabbits. In the latter animals a significant correlation between the number of staphylococci in the vegetations and in the circulation was found. We conclude that only monocytes have a measurable effect on the induction of Staphylococcus epidermidis endocarditis but during its course both granulocytes and monocytes keep the endocardial infection in check.

Animals↗

PubMed1983

Effect of strain of Staphylococcus aureus on synergism with Candida albicans resulting in mouse mortality and morbidity.

Nine Staphylococcus aureus strains isolated from patients with toxic shock syndrome (TSS), two strains from non-disease-associated sources, and four strains from disease (not TSS)-associated sources were characterized for the intraperitoneal dose necessary to kill 50% of exposed animals (LD50) and toxic shock toxin production and studied for synergistic effects on mouse mortality and morbidity when combined with a sublethal dose of Candida albicans and inoculated intraperitoneally. Representative toxic shock toxin-producing strains (free of other enterotoxins) exhibited the following unique set of characteristics when inoculated intraperitoneally into mice and compared with all other strains tested: (i) lowest virulence when inoculated alone into mice as determined by the LD50; (ii) greatest synergistic decrease in LD50 (up to 70,000-fold as compared to up to 200-fold for other strains) when combined with C. albicans and injected intraperitoneally; and (iii) induced a characteristic, dose-independent, temporal death pattern in dually injected animals. When sublethal dual doses were used, animals receiving disease (TSS and not TSS)-associated S. aureus in combination with C. albicans developed symptoms, but some differences in symptomatologies, depending on the strain, were observed. The symptoms included conjunctivitis; gastrointestinal, neurological, and circulatory abnormalities; rash followed by desquamation; and patchy baldness. Although overlap in symptoms between animal treatment groups was observed, certain symptoms (neurological sequeae and petechial hemorrhages) were observed only in animals inoculated with a specific S. aureus strain combined with C. albicans. Animals receiving sublethal dual doses, which included non-disease-associated S. aureus, did not develop symptoms. When Staphylococcus epidermidis was combined with C. albicans and inoculated into mice, no synergistic effects on morbidity or mortality were observed.

Animals↗

PubMed1983

Detection of anti-teichoic acid immunoglobulin G antibodies in experimental Staphylococcus epidermidis endocarditis.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of rabbit immunoglobulin G (IgG) antibodies to purified cell wall teichoic acids from the Staphylococcus aureus Lafferty strain and three strains of coagulase-negative staphylococci. Significant immunological cross-reactivity occurred only between the teichoic acid of S. aureus and one coagulase-negative preparation. The ELISA was used to determine the serum IgG response to Staphylococcus epidermidis in a rabbit model of aortic valve endocarditis. Blood samples were drawn before inoculation and then every 5 days until death or sacrifice at 32 to 35 days postinoculation. Valve vegetations were culture positive at autopsy in 16 (59%) of the 27 catheterized rabbits. Antibody titers in this culture-positive group and the culture-negative group began to rise as early as day 6. Although both groups demonstrated an antibody response, the culture-positive group attained a significantly higher titer on days 26 and 31. Antibodies also rose in a control group of rabbits without a heart catheter but which were inoculated with bacteria. Again, the antibody titer was significantly less than that for the culture-positive group. This ELISA may be useful for the diagnosis of coagulase-negative staphylococcal infections in humans.

Animals↗

PubMed1984

Chemical and biological characterization of a gonococcal growth inhibitor produced by Staphylococcus haemolyticus isolated from urogenital flora.

The purified antigonococcal substance produced by Staphylococcus haemolyticus no. 7 has shown a broad antigonococcal spectrum and a narrow antibacterial spectrum. The inhibitor produced in vitro was also active in the guinea pig subcutaneous chamber. The inhibitor has shown hemolytic activity; the human, horse, and mouse erythrocytes were the most susceptible. Hemolytic and antigonococcal activities were inhibited in the presence of phosphatidylcholine. The amino acid composition of the antigonococcal substance was characterized by the absence of proline, tyrosine, histidine, cysteine, and tryptophan. The molecular weight was found to be 2,565, and the major isoelectric points were 4.8 and 4.9 in the presence of 8 M urea and 4.6 without urea. The inhibitor has some properties similar to those of the delta toxin of Staphylococcus aureus, although the two substances are different based mainly on their chemical characteristics. Also an antiserum directed against the gonococcal inhibitor did not give a precipitation line with the delta toxin, indicating that the two substances are antigenically unrelated.

Amino Acids↗

PubMed1985

Effect of fibronectin on adherence of Staphylococcus aureus to fibrin thrombi in vitro.

Staphylococcus aureus binds to purified fibronectin in solution and may bind to fibronectin present in wound tissue. When incorporated into a solid fibrin thrombus, however, plasma fibronectin may fail to bind S. aureus, because the S. aureus-binding sites on fibronectin may be occupied by fibrin. Both S. aureus and fibrin bind to the same 27-kilodalton amino-terminal fragment of fibronectin. To determine whether fibronectin incorporated into fibrin still promotes the adherence of S. aureus, we clotted citrated normal plasma and fibronectin-depleted plasma onto petri dishes. We then measured bacterial adherence to these in vitro fibrin thrombi. We found that the adherence of five of seven S. aureus strains decreased significantly (by 26 to 58%) when fibronectin had been depleted from the fibrin thrombi. Adding fibronectin back reversed this decrease in adherence. The reversal was dose dependent; the increase was in proportion to the amount of fibronectin added back to the plasma. Bacteria known not to bind to fibronectin (Escherichia coli and Staphylococcus epidermidis) adhered 100-fold less than S. aureus, and their adherence was unaffected by the absence of fibronectin in the fibrin thrombus. We conclude that fibronectin incorporated into solid fibrin thrombi does mediate the adherence of most S. aureus strains to fibrin thrombi. Fibronectin may be an important molecule that mediates the adherence of S. aureus to fibrin in wounds.

Adhesiveness↗