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Examination of the glycocalyx of four species of Staphylococcus by transmission electron microscopy and image analysis.

The coagulase-negative staphylococci have become important pathogens in human infections involving foreign bodies. The bacterial glycocalyx is a major mediator of attachment of these organisms to medical devices, but the glycocalyx is sometimes difficult to demonstrate. A combination of the techniques of transmission electron microscopy (TEM) and image analysis enabled investigators to reveal the glycocalyx which was previously indiscernible. Eight strains of coagulase-negative staphylococci, including Staphylococcus epidermidis, S. hominis, S. lugdunensis, and S. schleiferi subspecies schleiferi, were grown, treated with anti-staphylococcal serum to stabilize the glycocalyx, and examined by TEM. Image analysis of negatives was then used to enhance the visual images which showed far more glycocalyx than previously seen by TEM alone.

Bacterial Capsules↗

Differentiation between bacterial species and sub-species by pyrolysis mass spectrometry of extracted DNA.

Whole cell samples from cultures of Staphylococcus aureus, S. hominis, S. epidermidis and Streptococcus pyogenes were analysed by pyrolysis mass spectrometry and the results were compared with Py-MS-derived analyses of samples of DNA extracted from the same organisms. Py-MS analysis differentiated the four organisms in both circumstances. These results challenge previous assumptions that Py-MS is restricted to detecting phenotypic differences, although the basis for the differentiation of the DNA extracts has yet to be determined.

DNA, Bacterial↗

Pulsed-field gel electrophoresis of the genomic restriction fragments of coagulase-negative staphylococci.

The genomes of 47 coagulase-negative staphylococcal strains assigned to different species were analysed by pulsed-field electrophoresis. The strains were clustered on the basis of their similarity in the SmaI restriction patterns into various groups, each group consisting of the type strain and the strains whose SmaI restriction patterns were similar to that of the type of strain. The SmaI restriction groups seem to correspond to the following species: Staphylococcus warneri, S. hominis, S. xylosus, S. lugdunensis, S. kloosii, S. haemolyticus, S. lentus, S. cohnii, S. equorum, S. chromogenes, S. saprophyticus, S. simulans, S. carnosus, S. capitis and S. auricularis. The species S. sciuri, S. caseolyticus, S. gallinarum, S. epidermidis and S. schleiferi were represented only by their type strains and showed no similarity in their SmaI restriction patterns neither to each other nor to all the other species investigated here. Thus, the classification of coagulase-negative staphylococcal strains into the above species seems to be confirmed also by genome restriction analysis carried out by pulsed-field gel electrophoresis.

DNA Restriction Enzymes↗

Variation in the expression of cell envelope proteins of coagulase-negative staphylococci cultured under iron-restricted conditions in human peritoneal dialysate.

Strains of coagulase-negative staphylococci (CNS), including Staphylococcus epidermidis, S. hominis, S. warnerii, S. simulans, S. capitis, S. haemolyticus and S. saprophyticus, were isolated from patients with continuous-ambulatory-peritoneal-dialysis-related peritonitis. The cell wall and cytoplasmic membrane protein profiles of CNS strains cultured in either nutrient broth (NB) or pooled human peritoneal dialysate (HPD) were compared. Some interspecies variation in both the wall and membrane protein profiles was noted. However, the cell wall protein profiles of HPD-grown CNS strains differed markedly from those cultured in NB. Growth in HPD resulted in a marked reduction in the total number of cell-wall-associated proteins but up to three antigenically related proteins in the 40-56 kDa range, depending on the species, predominated. Growth in HPD also resulted in the induction of two iron-repressible cytoplasmic membrane proteins (IRMPs) of 32 and 36 kDa in S. epidermidis. Other CNS strains only appeared to express a single IRMP, which varied in molecular mass from 32 to 36 kDa. Whilst the IRMP in these CNS strains showed considerable antigenic homology with the 32 kDa IRMP, the S. warneri IRMP showed cross-reactivity with both the 32 and 36 kDa IRMPs of S. epidermidis. Immunoblotting experiments revealed that whilst the CNS cell wall proteins were poorly immunogenic, the IRMPs were the immunodominant CNS protein antigens, reacting strongly with antibodies present in HPD. This finding provides evidence to suggest that the IRMPs are expressed in vivo during infection.

Antibodies, Bacterial↗

Intravenous rifampicin in neonates with persistent staphylococcal bacteraemia.

UNLABELLED: Addition of intravenous rifampin is reported to be useful in prompt clearance of persistent coagulase negative staphylococcal (CONS) bacteraemia in high-risk neonates. Four neonates (mean birthweight 823 g, mean gestation 25 wk) with persistent CONS bacteraemia for > 7-10 d (mean 11) were treated with i.v. rifampicin (10 mg/kg/12 h x 10 d) while continuing vancomycin (15 mg/kg/24 h). Their age at time of infection ranged from 2 to 11 d. The mean (range) vancomycin peak and trough concentrations were 29 (25-35) and 6 (4-10) microg/ml, respectively. The blood isolates were Staphylococcus epidermidis, S. hominis, and S. haemolyticus. Addition of rifampicin was associated with prompt clearance of bacteraemia within 48 h (n = 3) and 5 d (n - 1). Rifampicin-related adverse effects such as abnormal liver function tests and thrombocytopenia did not occur. CONCLUSION: Addition of i.v. rifampicin to vancomycin may optimize the outcome of persistent CONS bacteraemia and the risk of bacterial resistance related to prolonged exposure to vancomycin.

Bacteremia↗

In vivo study of an antimicrobial surgical drape system.

We performed a double-blind clinical study to determine the efficacy of nonwoven laparotomy drapes in which 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride, an antimicrobial agent, was chemically bonded to the absorbent reinforcement surrounding the fenestration. The reinforcement portion of the surgical drape that contained the fenestration was segmented into four identical-appearing sections, two on each side of the fenestration. One segment on each side was antimicrobial. The locations of the treated segments were randomly varied. At the end of each operation, test strips were removed. Bacteria were harvested from each segment by mechanical agitation. Bacterial CFU were counted. There were 110 surgical cases in the study, including clean, clean contaminated, and contaminated procedures. Data analysis divided the cases into two distinct groups. Group 1 was composed of 59 cases in which less than 30 total CFU was recovered from the four test samples. The average duration of surgery for this group was 1.8 h. Group 2 was composed of 51 cases in which bacterial recovery was in excess of 30 CFU per procedure (range, 30 to 25,000 bacterial CFU). The average duration of surgery was 3.3 h. Bacterial reduction in the treated strips was 84%. The most common organisms identified on the laparotomy drapes were Staphylococcus epidermidis, S. hominis, and Micrococcus luteus. This study demonstrated that the reinforcement of a laparotomy drape is a reservoir for potential pathogens. It demonstrated that an organosilicon quaternary ammonium antimicrobial agent covalently bonded to the reinforcement reduced the number of potential pathogens surrounding the surgical incision by 84%, independent of the size of the bacterial challenge.

Anti-Infective Agents, Local↗

Bacteriologic studies of skin, tissue fluid, lymph, and lymph nodes in patients with filarial lymphedema.

Filarial lymphedema is complicated by frequent episodes of dermatolymphangioadenitis (DLA). It is not certain whether DLA is of filarial or bacterial etiology. The frequency of episodic DLA does not depend on the presence or absence of microfilariae. Antibiotic therapy is effective in prevention and treatment of DLA. These observations point to the bacterial rather than filarial etiology of DLA. Skin and lymph node biopsies, tissue fluid, lymph, and blood from patients with chronic filarial lymphedema, and during acute episodes of DLA, were cultured for detection of bacteria. A high prevalence of bacterial isolates from the tissue fluid (64%), lymph (75%), and inguinal lymph nodes (66%) of limbs with filarial lymphedema was found. Bacillus cereus, Staphylococcus epidermidis, S. hominis, S. capitis, S. xylosus, and Micrococcus spp. were the most common isolates. Bacteria were also isolated from the blood of patients with recent episodes of DLA, with strains of the same phenotype and antibiotic sensitivity in all specimens from patients with DLA. Bacterial strains of the same phenotype and antibiotic sensitivity were documented on the toe web surface and in tissue fluid (25%), lymph (26%), or lymph nodes (41%). Increasing prevalence of bacterial isolates in tissue fluid, lymph, and lymph nodes was observed in advanced stages of lymphedema. Bacilli and cocci were sensitive to gentamicin, tetracyline, rifampicin, vancomycin, kanamycin and cotrimoxazole, and least sensitive to penicillin. Blood cultures of patients in the periods between DLA attacks were negative. In healthy controls without edema and episodes of DLA, tissue fluid did not contain bacteria. In lymph, only single colonies of Micrococcus and Acinetobacter were cultured in 12% of the cases. Impaired lymph drainage and lack of elimination of penetrating bacteria may be responsible for progression of lymphedema and recurrent attacks of DLA.

Adolescent↗

[Study on the inhibitory activity, in vitro, of baicalein and baicalin against skin fungi and bacteria].

In this paper, we concentrated in examining, in vitro, the antiseptic activity of the baicalein and baicalin upon the seventeen pathogenic skin fungal and sixteen skin bacterial strains, these two flavonic compounds were known principally as the biosubstances of a traditional Chinese medicinal plant: Scutellaria baicalensis. In agar media, the baicalein possessed potent specific activity against the pathogenic yeasts with MICs of 70-100 micrograms/ml; But in the same condition, no inhibitory effect was observed upon dermatophytes and filamentous imperfect fungi for baicalein, and upon all used strains for baicalin. According to the antibacterial test of baicalein, a high efficacy was achieved against certain causative specie of axillary and foot's odour such as Micrococcus sedentarius, Staphylococcus epidermidis, S. hominis and C. xerosis with a MICs inferior to 250 micrograms/ml. The good inhibitory activity of baicalein could be linked to the group hydroxyl (-OH) in position seven of the molecule.

Anti-Infective Agents, Local↗

[Differentiation of staphylococci from sheep and goat milk samples].

A total of 447 micrococcaceae strains isolated from 88 ewe and 359 goat milk samples from cases of chronic mastitis were differentiated by means of the ATB 32 STAPH-test. Of these strains 389 (= 87%) could be identified. Fourteen strains were sensitive in the bacitracin-resistance-test and therefore classified as Micrococcus spp. In ewe milk following Staphylococcus spp. were found: S. epidermidis, S. aureus, S. lentus, S. xylosus, S. warneri, S. equorum, S. haemolyticus, S. simulans, S. hominis and S. saprophyticus. Staphylococcus spp. identified in goat milk samples were: S. epidermidis, S. aureus, S. caprae, S. lentus, S. simulans, S. capitis, S. lugdunensis, S. xylosus, S. chromogenes, S. hominis, S. arlettae, S. warneri, S. sciuri, and S. saprophyticus. Highest cell counts in the milk of both animals species, and the highest incidence of clinical udder alterations were caused by S. aureus. Increases in milk cell counts as well as pathological udder findings were observed in coagulase-negative staphylococcal infections for novobiocin-sensitive Staphylococcus spp. (S. epidermidis, S. warneri, S. simulans, S. lugdunensis, and S. chromogenes) and several S. lentus strains.

Animals↗

Expression of glycocalyx by coagulase-negative Staphylococcus species isolated from bovine milk.

Two hundred and six strains of coagulase-negative Staphylococcus species were assessed for expression of glycocalyx on serum soft agar, india ink and adherence techniques. The organisms were maintained on trypticase soy agar plates at 4 degrees C for 30 d (120 strains) or stored at -80 degrees C in skim milk for 90 d (60 strains). Additionally, 26 milk samples from cows known to have excreted coagulase-negative staphylococci were used to inoculate serum soft agar directly. Nine of 26 direct culture samples and 43 of 180 strains maintained for an extended period had diffuse-type growth on serum soft agar. The proportion that exhibited an unstained halo by india ink was similar regardless of storage time. Slime production determined by in vitro adherence revealed a higher proportion of positive strains than had been predicted by serum soft agar or india ink techniques. More strains of Staphylococcus chromogenes, Staph. epidermidis, Staph. hominis, Staph. simulans and Staph. warneri expressed glycocalyx than other coagulase-negative Staphylococcus species. These results suggest that most coagulase-negative staphylococci produce slime rather than a capsule. However, evidence for classical encapsulation was demonstrated in several strains by india ink. The finding that Staphylococcus species other than Staph. aureus isolated from bovine milk are capable of glycocalyx production may be of importance in investigations on the relationship between staphylococci and host defence mechanisms.

Animals↗

[Study on etiology of nongonococcal urethritis].

One thousand one hundred and fifty-seven samples from urogenital tract were detected by isolating culture and immunofluorescence. The positive rates of Chlamydia trachomatis (CT), Ureaplasma Urealyticum (UU), Mycoplasma hominis (Mh), Candida (Cd), Staphylococcus aureus were 27.8%, 33.5%, 25.6%, 11.5%, 23% respectively. The rate of mixed infection caused by at least two pathogens was 19.8%. About 90% of the infected patients were from 20 to 40 years old. The related factors of pathogen detection were also studied.

Adolescent↗

Comparison of methods for the identification of coagulase-negative staphylococci.

Coagulase-negative staphylococci (CNS) species identification is still difficult for most clinical laboratories. The scheme proposed by Kloos and Schleifer and modified by Bannerman is the reference method used for the identification of staphylococcal species and subspecies; however, this method is relatively laborious for routine use since it requires the utilization of a large number of biochemical tests. The objective of the present study was to compare four methods, i.e., the reference method, the API Staph system (bioMérieux) and two methods modified from the reference method in our laboratory (simplified method and disk method), in the identification of 100 CNS strains. Compared to the reference method, the simplified method and disk method correctly identified 100 and 99% of the CNS species, respectively, while this rate was 84% for the API Staph system. Inaccurate identification by the API Staph method was observed for Staphylococcus epidermidis (2.2%), S. hominis (25%), S. haemolyticus (37.5%), and S. warneri (47.1%). The simplified method using the simple identification scheme proposed in the present study was found to be efficient for all strains tested, with 100% sensitivity and specificity and proved to be available alternative for the identification of staphylococci, offering, higher reliability and lower cost than the currently available commercial systems. This method would be very useful in clinical microbiology laboratory, especially in places with limited resources.

Bacterial Typing Techniques↗

Species identification of coagulase-negative staphylococci from urinary tract isolates.

A new scheme for identification of coagulase-negative staphylococci was applied to 138 consecutive urinary isolates of coagulase-negative staphylococci. The most common species were Staphylococcus epidermidis (53%), S. hominis (12%), and S. haemolyticus (10%). S. saprophyticus comprised only 5%. The disk method for antibiotic susceptibility for all species grouped together disclosed resistance most commonly to penicillin (35%), tetracycline (33%), methicillin (27%), and sulfonamide (24%). This pattern was also seen specifically with S. epidermidis. Further studies are needed to determine the incidence of species-specific antibiotic resistance and species-specific infection by site. This may be of particular interest in those patients with nosocomial infections due to coagulase-negative staphylococci.

Anti-Bacterial Agents↗

Molecular characterization of methicillin-resistant coagulase-negative staphylococci from a neonatal intensive care unit.

OBJECTIVE: To evaluate clonal dissemination of methicillin-resistant coagulase-negative staphylococci (CNS). SETTING: Neonatal intensive care unit of a 180-bed, university-affiliated general hospital. PATIENTS: Neonates admitted to the neonatal intensive care unit between March 1999 and October 2000, from whom CNS were isolated as a unique pathogen. Patients from other wards from whom epidemiologically unrelated staphylococci strains were obtained served as control-patients. METHODS: Conventional methods were used for phenotypic characterization of CNS. Methicillin resistance was determined by mecA polymerase chain reaction (PCR) amplification. Genotypic characterization was done by random amplification of DNA with degenerated primers (RAPD) and repetitive element sequence-based PCR (rep-PCR). RESULTS: Forty methicillin-resistant CNS isolates obtained from neonates were characterized as Staphylococcus epidermidis (33), S. hominis (5), S. warneri (1), and S. auricularis (1). Both RAPD and rep-PCR indicated the presence of 4 different clones among the 33 S. epidermidis isolates. In turn, the 4 randomly selected, epidemiologically unrelated methicillin-resistant CNS strains obtained from control-patients showed 3 new profiles by RAPD and 2 by rep-PCR, which differed from the corresponding patterns mentioned earlier. Persistence of S. hominis in a neonate could be assessed by both genotypic techniques. CONCLUSIONS: The molecular characterization of the methicillin-resistant CNS studied indicated dissemination of one particular methicillin-resistant CNS clone among the neonates in the ward studied. Although RAPD showed a superior power to discriminate among methicillin-resistant CNS isolates, both RAPD and rep-PCR detected intraspecific and interspecific genomic diversity.

Argentina↗

Topoisomerase sequences of coagulase-negative staphylococcal isolates resistant to ciprofloxacin or trovafloxacin.

Coagulase-negative staphylococcal isolates (n = 188) were screened for susceptibility to oxacillin, ciprofloxacin, and trovafloxacin, a new fluoroquinolone. At an oxacillin concentration of >/=4 microg/ml, 43% were methicillin resistant; of these, 70% were ciprofloxacin resistant (MIC, >/=4 microg/ml). Of the methicillin-resistant, ciprofloxacin-resistant isolates, 46% were susceptible to </=2 microg of trovafloxacin per ml and 32% were susceptible to </=1 microg of trovafloxacin per ml. Sixteen isolates, including twelve that expressed fluoroquinolone resistance, were chosen for detailed analysis. Identification of species by rRNA sequencing revealed a preponderance of Staphylococcus haemolyticus and S. hominis among fluoroquinolone-resistant strains. Segments of genes (gyrA and grlA) encoding DNA gyrase and DNA topoisomerase IV were sequenced. Considerable interspecies variation was noted, mainly involving noncoding nucleotide changes. Intraspecies variation consisted of coding changes associated with fluoroquinolone resistance. As for S. aureus, ciprofloxacin resistance (MIC, >/=8 microg/ml) and increased trovafloxacin MICs (0.25 to 2 microg/ml) could be conferred by the combined presence of single mutations in each gyrA and grlA gene. Trovafloxacin MICs of >/=8 microg/ml also occurred, but these required an additional mutation in grlA.

Anti-Infective Agents↗

Bactericidal activity of teicoplanin in an in-vitro two-compartment kinetic model.

The bactericidal activity of teicoplanin was studied in a model system in which antibiotic concentration is continuously varied. A two-compartment open model was used to reproduce, in vitro serum pharmacokinetics of teicoplanin in humans during 24 h after iv administration. Staphylococcal and streptococcal strains of various species were tested. Teicoplanin showed rapid killing of Staphylococcus epidermidis and Staph. hominis. All strains of Staph. epidermidis were rapidly killed in spite of the high MIC values (4-16 mg/l). The killing effect against Staph. haemolyticus was less rapid and marked than against Staph. epidermidis, with strain to strain variation. A 99.9% kill was achieved for most strains within 22 h, but with other isolates regrowth occurred which was due to the presence of highly resistant cells in the original population. Other staphylococci (Staph. aureus, Staph. saprophyticus) and Streptococcus pyogenes, Str. bovis and Str. salivarius were reduced by 99.9% within 22 h. Bactericidal activity against other streptococci (Str. mutans, Str. agalactiae, Str. faecalis, Str. faecium) was less marked; against Str. sanguis teicoplanin was bacteriostatic.

Anti-Bacterial Agents↗

Detection of cervical immunoglobulin A in normal pregnancy.

The aim of our study was to evaluate a feasible method to quantify the immunoglobulin A concentration in the cervical mucus of women with a normal singleton pregnancy. In 60 immunologic healthy pregnant women cervical mucus samples were taken at a random time in pregnancy using an absorbing cylindrical cotton-swab stick. In this cervical mucus immunoglobulin A concentration was measured by radial immunodiffusion. A vaginal bacterial swab was taken from each woman. Concentration of immunoglobulins in maternal serum was estimated. There was no statistically significant difference of cervical immunoglobulin A concentration between the investigated groups (p = 0.952): 18-24 gestational weeks (gw): 52.8 (6.6-258.4) mg/l; 25-29 gw: 89.3 (4.8-193.8) mg/l; 30-34 gw: 55 (1.4-326) mg/l; 35-40 gw: 59.2 (4-400.9) mg/l. Women with a normal vaginal flora showed a significantly higher cervical immunoglobulin A concentration than those with a pathological colonization: 92.2 (6.6-400.9) mg/l vs. 42.5 (1.4-326) mg/l (p < 0.05). The serum levels of immunoglobulins A, A1, A2, M and G do not correlate to cervical immunoglobulin A levels nor to gestational age. In normal pregnancy, cervical immunoglobulin A concentration does not change with advancing gestational age, but a pathological vaginal colonization seems to be associated with decreased immunoglobulin A levels.

Adolescent↗

The effect of benzoyl peroxide on cutaneous micro-organisms in vitro.

The survival curves of cutaneous micro-organisms in the presence of benzoyl peroxide were investigated. All the curves exhibited a shoulder prior to exponential cell death. Benzoyl peroxide was lethal to the cutaneous organisms tested and they varied in sensitivity increasing as follows: Propionibacterium acnes, Staphylococcus capitis, Staph. epidermidis, Staph. hominis, Prop. avidum, Prop. granulosum and Pityrosporum ovale.

Benzoyl Peroxide↗