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Defective phagocytosis confined to Staphylococcus aureus in a female infant with recurrent infections.

Defective chemotaxis and phagocytosis of Staphylococcus aureus was identified in a female infant with marked hepatosplenomegaly and recurrent infections. Neutrophil mobilization from the marrow and marginal pool; random mobility; phagocytosis of yeast particles, latex beads and carbon particles; phagocytosis and intracellular killing capacity of Streptococcus pyogenes and E. coli; and NBT dye reduction were normal. Infiltration of neutrophils was depressed in the skin window test. The complement system and cellular immunity were intact. The patient also had a persistent EB virus infection. Defective phagocytosis limited to Staphylococcus aureus seems to be caused by an intrinsic cellular defect, such as congenital defect in neutrophil receptors for Staphylococcus aureus.

Bacterial Infections↗

Necrotizing fasciitis caused by Staphylococcus aureus.

Two patients with rapidly progressive necrotizing fasciitis of a lower extremity due to Staphylococcus aureus as a single pathogen are described. In both patients the portal of entry was attributed to needle puncture (intra-articular injection and intravenous catheter, respectively), followed by bacteremia. Necrotizing fasciitis occurred in a site remote from the needle puncture, suggesting metastatic infection. One patient developed toxic shock syndrome and the other a sunburn-like rash and erythematous mucosae with strawberry tongue. One patient died, and the other required above-knee amputation due to secondary infectious complications. Staphylococcus aureus may mimic the presentation of invasive group A streptococcal infections. A history of needle puncture should alert the physician to the possibility of Staphylococcus aureus infection.

Aged↗

Clonal heterogeneity, distribution, and pathogenicity of methicillin-resistant Staphylococcus aureus.

Four thousand eighty-eight Staphylococcus aureus isolates obtained from patients hospitalised in a university clinic and four community hospitals over a period of one year were screened for methicillin resistance. A resistance rate of 5% was detected among initial isolates. Distribution of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus showed an increased prevalence of MRSA in clinically significant specimens such as blood, central venous catheter tips, bronchial secretions, and wound secretions. Typing of 110 MRSA strains (initial isolates) by macrorestriction analysis of chromosomal DNA revealed 26 different genotypes that could be divided into five epidemic and 21 sporadic strains. More than 50% of all isolates belonged to one type that was confirmed to be closely related to the "southern-German" epidemic strain. Production of virulence factors such as enterotoxin A-D and toxic shock syndrome-toxin 1 among MRSA strains (initial isolates) occurred in ten of 26 different MRSA types. A strong correlation between genotype and toxin production was demonstrated.

Clone Cells↗

Clinical and epidemiological findings in mechanically-ventilated patients with methicillin-resistant Staphylococcus aureus pneumonia.

Over the 5-year period from 1990 to 1994, a prospective cohort study was conducted to define the clinical and epidemiological characteristics of ventilator-associated methicillin-resistant Staphylococcus aureus (MRSA) pneumonia acquired during a large-scale outbreak of MRSA infection. Of 2411 mechanically ventilated patients, 347 (14.4%) acquired MRSA, 220 (63.4%) had MRSA positive respiratory tract samples and 41 (18.6%) developed ventilator-associated MRSA pneumonia. The overall attack rate for ventilator-associated MRSA pneumonia was 1.56 episodes/1000 ventilator days, but annual attack rates varied according to the trend of the outbreak (range 4.9-0.2). In comparison with methicillin-sensitive Staphylococcus aureus (MSSA), which was implicated in 98 episodes of ventilator-associated pneumonia, MRSA caused exclusively late-onset ventilator-associated pneumonia, while MSSA caused both early-onset [55 of 98 (56.1%) episodes] and late-onset [43 of 98 (43.8%) episodes] ventilator-associated pneumonia. Logistic regression analysis of all patients with Staphylococcus aureus pneumonia revealed intubation for more than 3 days (odds ratio (OR),1.11; confidence interval (CI):1.03-1.18) and prior bronchoscopy (OR,5.8; CI,1.85-18.19) to be independent variables associated with MRSA pneumonia. The results indicate that MRSA ventilator-associated pneumonia is a frequent complication in intensive care patients, manifesting itself as late-onset pneumonia in patients who have been intubated for prolonged periods and/or have often undergoing previous bronchoscopy.

Adult↗

Simple enzymatic method for rapid identification of a Staphylococcus aureus subspecies aureus biovar.

In order to correctly identify a new biovar of Staphylococcus aureus subsp, aureus, (NBSA) a simple, rapid, and reliable enzymatic assay was developed. The assay was based on the detection of the production of three enzymes: alpha-glucosidase, beta-glucosidase and beta-N-acetyl-glucosaminidase. Of a total of 46 isolates of Staphylococcus aureus subsp. aureus from clinical specimens, the new assay correctly identified 19 as NBSA and 27 as typical Staphylococcus aureus subsp. aureus. Among the 19 NBSA isolates, 15 (79%) showed a clear biochemical profile while only four isolates (21%) showed a less well-defined enzymatic combination, due to a phenotypic alteration caused by subculturing. Since this assay is both simple to perform and inexpensive, it is potentially applicable in the laboratory.

Acetylglucosaminidase↗

Evaluation of a commercial test kit for rapid detection of Staphylococcus aureus in blood cultures.

The presence of Staphylococcus aureus in positive blood cultures could be rapidly confirmed by the use of a commercial test kit (Rapidec Staph; bioMérieux, France) that detects coagulase in the culture broth after 2 h of incubation. This kit detected all 35 Staphylococcus aureus strains from 117 blood cultures with gram-positive cocci growing in clusters. The sensitivity and the specificity of the technique were 100% and 98.8%, respectively. The Rapidec Staph kit appears to be a simple and reliable technique for the rapid detection of Staphylococcus aureus in blood cultures.

Bacteremia↗

A multicentre study: Staphylococcus and Enterococcus susceptibility to antibiotics.

A multicentre study to evaluate the susceptibility of Gram-positive cocci isolated from clinical samples, was performed by six centres working in different areas of Italy. We examined 4,544 strains of Staphylococcus aureus, 4,381 strains of coagulase-negative staphylococci and 2,478 strains of enterococci. The following antibiotics were tested: penicillin G, ampicillin, amoxicillin, piperacillin, imipenem, oxacillin, ofloxacin, pefloxacin, ciprofloxacin, gentamicin, tobramycin, amikacin, netilmicin, rifampicin, clindamycin, tetracycline, cotrimoxazole, erythromycin, chloramphenicol, vancomycin and teicoplanin. Oxacillin-susceptible staphylococci confirmed their susceptibility to many other antimicrobial agents while oxacillin-resistant strains confirmed their multiple and frequent resistance to antibiotics. Resistance to oxacillin, cotrimoxazole and chloramphenicol was more frequent in coagulase-negative staphylococci than in Staphylococcus aureus. Aminoglycosides, rifampicin and quinolones were more active against coagulase-negative staphylococci than against Staphylococcus aureus. Enterococci were susceptible to penicillins and imipenem, and moderately susceptible to ciprofloxacin. Susceptibility of 70-79% was observed with high levels of aminoglycosides. Excellent results against staphylococci and enterococci were observed with vancomycin and teicoplanin.

Anti-Bacterial Agents↗

Activity of cefpirome combined with beta-lactamase inhibitors and affinity for the penicillin-binding proteins of methicillin-resistant Staphylococcus aureus.

The susceptibility of 47 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) to cefpirome, ceftazidime and methicillin was determined with Isosensitest media, with/without 5% NaCl and incubation at 30 degrees, 37 degrees and 44 degrees C for 24 and 48 h. At 24 h the MIC50 of cefpirome was 8 mg/l compared to 64 mg/l ceftazidime; at 48 h this increased to 32 mg/l cefpirome. The addition of 10 mg/l clavulanic acid or sulbactam lowered the MIC of cefpirome (at 48 h) by greater than four-fold in 23% and 11% of the strains, respectively. Cefpirome had primary affinity for penicillin-binding protein (PBP) 1 and 2 in five MRSA and one methicillin-susceptible Staphylococcus aureus. PBP 2a was present in all MRSA and was not saturated by 64 mg/l cefpirome. Clavulanic acid at a concentration of 10 mg/l bound to PBP 2 by greater than 50% in all strains, and when combined with cefpirome, the density of PBP 2a was also reduced but not completely abolished. The data from this study suggests that the mechanism of synergy of a beta-lactamase inhibitor plus a cephalosporin for MRSA may be due to an additive effect against PBPs and not just inhibition of a beta-lactamase. No cefpirome-resistant mutants could be selected from a methicillin-susceptible Staphylococcus aureus, but mutants were selected from an MRSA (expressing homogeneous methicillin resistance) for which MICs of cefpirome were 8 to 32 mg/l.

Bacterial Proteins↗

Interference of Staphylococcus aureus lipase with human granulocyte function.

The influence of purified Staphylococcus aureus lipase on granulocyte function and morphology was studied. The lipase itself was strongly chemotactic; in addition preincubation of granulocytes with low concentrations of lipase enhanced the directed movement, as assayed in the agarose system. Higher concentrations of lipase, in contrast, gave a progressive reduction of granulocyte chemotaxis; at 12 micrograms lipase per ml, cells were almost immobilized. Phagocytic killing of Staphylococcus aureus by granulocytes preincubated with lipase was reduced in a dose-dependent manner. At 12 micrograms lipase per ml almost no staphylococcal killing occurred. This was mainly accounted for by a reduction of bacterial uptake, but some decrease in intragranulocytic killing was also noted. These functional alterations, which can all be ascribed to an interference with membrane functions, were associated with marked changes of the granulocyte surface structure, which was denuded and lacked normal microvilli. The effects of lipase were partly retained after heat inactivation of lipase activity, indicating that the effects of staphylococcal lipase on granulocyte function are not due to enzymatic activity alone. These effects of lipase may be an important virulence factor and contribute to the preferential location of lipase-producing Staphylococcus aureus strains at deep sites of infection.

Chemotaxis, Leukocyte↗

Latex agglutination for rapid identification of methicillin-resistant Staphylococcus aureus recovered from selective media.

The accuracy of combining latex agglutination with selective media for the identification of methicillin-resistant Staphylococcus aureus (MRSA) was determined. Test strains were identified by latex agglutination on blood agar, the heat-stable thermonuclease test and broth microdilution MICs of oxacillin and included 97 MRSA, 56 methicillin-susceptible Staphylococcus aureus, 52 methicillin resistant, and 49 methicillin-susceptible Staphylococcus species. Isolates were grown on trypticase-soy agar with 5% sheep red blood cells (TSAB), Mueller-Hinton agar (MHA), mannitol-salt agar (MSA), and four media designed for the selective growth of MRSA:TSAB with clindamycin and gentamicin, MHA with oxacillin, MSA with oxacillin, and lipovitellin-salt-mannitol agar (LVSM) with 1 microgram oxacillin disks applied. The mean sensitivity, specificity, and positive predictive value for the combination of latex agglutination with selective media for the identification of MRSA was 96%, 99% and 98% respectively.

Culture Media↗

Effect of azlocillin and piperacillin in subinhibitory and inhibitory concentrations on Staphylococcus aureus and Pseudomonas aeruginosa in broth, in serum and in the presence of human polymorphonuclear leukocytes.

The bactericidal activity of azlocillin and piperacillin was tested at concentrations of 1/4 the MIC, the MIC and four-fold the MIC agents a serum-resistant Staphylococcus aureus and a serum-resistant Pseudomonas aeruginosa strain in broth, in serum and in the presence of leukocytes. The antibacterial activity of azlocillin and piperacillin in serum against Staphylococcus aureus was slightly better than in broth (p greater than 0.05); both compounds were distinctly less active against Pseudomonas aeruginosa in serum than in broth (p less than 0.05). Both antibiotics enhanced susceptibility of Pseudomonas aeruginosa to leukocyte killing without serum (p less than 0.05), whereas leukocyte killing of Staphylococcus aureus was hardly improved even at the MIC and four-fold the MIC of both compounds. The antibacterial activity of azlocillin and piperacillin against both bacterial strains was most pronounced in the presence of leukocytes and serum. A marked bactericidal effect was achieved at 1/4 the MIC, the effect not being further significantly enhanced (p greater than 0.05) at the MIC or four-fold the MIC.

Azlocillin↗

Methicillin-resistant Staphylococcus aureus in Europe.

In order to obtain pan-European data on methicillin-resistant Staphylococcus aureus (MRSA), 43 laboratories from ten European countries each screened 200 consecutive Staphylococcus aureus isolates for methicillin resistance. Only one isolate per patient was permitted. All participants used a uniform oxacillin-supplemented screening plate. MRSA isolates were sent to Munich for reconfirmation and further susceptibility testing. Phage typing of the MRSA strains was performed in Denmark. Of the 7,333 Staphylococcus aureus strains screened, 936 (12.8%) were methicillin resistant. The proportion of MRSA in the various European countries ranged from < 1% in Scandinavia to > 30% in Spain, France and Italy. Rates of resistance to the non-glycopeptide antibiotics were lowest for rifampin and highest for ciprofloxacin. Sixty percent of the methicillin-resistant strains originated from patients in surgical and medical departments, with wounds being the most common isolation source. MRSA was found more frequently in intensive care patients. Only 13% of the strains were non-typable, and 76% of the isolates belonged to phage group III. For each area phage typing detected one or a few dominating (epidemic) types, but 46% of the strains did not belong to these types; the MRSA population is thus a mixture of epidemic and non-epidemic strains. MRSA seems to be a growing problem, especially in southern Europe, where incidence and rates of antibiotic resistance are alarmingly high.

Anti-Bacterial Agents↗

Use of commercial particle agglutination systems for the rapid identification of methicillin-susceptible and methicillin-resistant Staphylococcus aureus.

The performance of a recently introduced Staphylococcus aureus identification system (Slidex Staph-Kit) was compared with that of currently available systems (Immuno Scan Staphlatex, Staphyloslide, Staphaurex and SeroSTAT II) for the identification of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus. The new system, which detects a capsular antigen common in MRSA, performed with equal or greater sensitivity than the other systems. None of the commercial systems was adversely affected by the methicillin susceptibility of the staphylococci when isolates were recovered from non-selective media. The greatest advantage of the anti-capsular monoclonal reagent was its improved performance on isolates recovered from selective media.

Humans↗

Nasopharyngeal carriage of Staphylococcus aureus and carriage of tetracycline-resistant strains associated with HIV-seropositivity.

The aim of this prospective study was to investigate the relationship between carriage of antibiotic-resistant Staphylococcus aureus and infection with the human immunodeficiency virus (HIV). A total of 554 pernasal swabs was taken during a six-month period from 554 adult patients attending three outpatient clinics and from inpatients from a hospital in Nairobi, Kenya. Overall, 121 swabs (22%) yielded Staphylococcus aureus, there being significantly higher carriage in HIV-positive patients (71/264, 27%) than in HIV-negative patients (50/290, 17%); p = 0.008. Antimicrobial resistance rates were determined for 110 isolates and were high for penicillin (91%) and tetracycline (72%) and low for erythromycin (8%), methicillin (3%), gentamicin (5%) and chloramphenicol (0%). Genetic analysis showed plasmids in the range of 24-42 MDa to be associated with beta-lactamase production and plasmids in the range of 3-5 MDa to be associated with resistance to tetracycline, erythromycin and trimethoprim. All nine erythromycin-resistant strains were from HIV-positive patients (p = 0.02). There was a significant association of tetracycline resistance with HIV seropositivity (p = 0.002). The association of HIV seropositivity with Staphylococcus aureus carriage and carriage of antibiotic-resistant strains against the background of the HIV epidemic are of relevance in individual patient care and raise concern for public health.

Adult↗

Propofol inhibits phagocytosis and killing of Staphylococcus aureus and Escherichia coli by polymorphonuclear leukocytes in vitro.

Polymorphonuclear leukocytes (PMNL) are important components of the immunological defence system which protects the human organism from invading bacteria. Using a fluorescence microscopic method, we examined the influence of propofol and its solvent intralipid on phagocytosis and killing of Staphylococcus aureus and Escherichia coli by PMNL in vitro. Propofol inhibited (P < or = 0.001) phagocytosis of Staphylococcus aureus as well as Escherichia coli. Killing of Staphylococcus aureus (P < or = 0.001) and of Escherichia coli (P < or = 0.01) was suppressed. Intralipid, by itself, impaired phagocytosis of Escherichia coli (P < or = 0.05). Apart from that, intralipid produced no relevant effects. Additional clinical studies regarding the influence of propofol on PMNL function are recommended.

Adult↗

Active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis.

A 26-year-old male was treated for acute hepatitis due to Epstein-Barr virus and infectious mononucleosis in our hospital. At 2 weeks after admission, there was relapse with high fever. A blood culture detected methicillin-resistant Staphylococcus aureus. A two-dimensional echocardiogram revealed severe aortic regurgitation and vegetation on the left coronary cusp of the aortic valve. The diagnosis was active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis. Following preoperative administration of vancomycin, the aortic valve was replaced with a Carbomedics prosthetic valve. The aortic valve was bicuspid, and the right cusp and non-coronary cusp were conjoined. As the focus of infection was localized to the left coronary cusp, the infected tissue was fully removed with resection of all the cusps. Although fever persisted long after the operation, the blood culture became negative for methicillin-resistant Staphylococcus aureus, and repeated echocardiograms including transesophageal echocardiogram showed no prosthetic valve infection. Vancomycin was administered until the C-reactive protein became negative at 45 days after the operation.

Acute-Phase Reaction↗

Long-term infectious complications and their relation to treatment duration in catheter-related Staphylococcus aureus bacteremia.

The optimal duration of treatment for catheter-related Staphylococcus aureus bacteremia is not known. Short courses (< or = 2 weeks) of therapy should be viewed with caution because essential data on late complications, such as osteomyelitis and metastatic abscesses, are lacking. This study represents a retrospective analysis of the data from 49 adult patients hospitalised in the period 1994-1996 (mean age, 57 years; range, 20-90 years; 47% male) and from whom Staphylococcus aureus was cultured concomitantly from peripheral blood and catheter segments. Forty-six venous catheters, two arterial catheters, and one unknown type of catheter were used. Forty-four patients were treated with effective anti-Staphylococcus aureus antibiotics. Twenty patients had a favourable outcome, defined as no complication and no death during 1 year of follow-up, 24 patients had complications, 14 patients died due to attributable mortality, and 5 other patients died of an underlying disease without showing signs or symptoms of a complication. Patients were categorised according to the duration of treatment. There were small differences between a shorter (1-14 days) and a longer (>14 days) course of antibiotics with regard to favourable outcome (41% vs. 33%), complications (48% vs. 53%), attributable death (31% vs. 20%), and death due to underlying disease (41% vs. 33%), respectively. The rates of complications and death were high, but a definite conclusion cannot be drawn because the study was underpowered. More randomised trials are needed, but, until the results of such trials are available, the duration of therapy should not be shortened to less than 14 days.

Adult↗

Antibiotic susceptibility and phage typing of methicillin-resistant and -sensitive Staphylococcus aureus clinical isolates at three periods during 1991-1997.

The aim of the study presented here was to evaluate the antibiotic susceptibility of Staphylococcus aureus over a 7-year period. A total of 2,122 clinical isolates of Staphylococcus aureus were collected from hospitalized patients at 3-year intervals during the period 1991-1997. The prevalence of methicillin-resistant isolates was 41.6%, 38.2% and 36% in 1991, 1994 and 1997, respectively; all of these isolates were sensitive to vancomycin. Over the study period, resistance to pristinamycin and fusidic acid increased slightly and resistance to imipenem, rifampicin and amikacin increased greatly, while resistance to trimethoprim/sulfamethoxazole decreased. For methicillin-sensitive Staphylococcus aureus isolates, significantly increased resistance was observed against amikacin only. Phage typing was conducted using the international set of phages. All of the isolates that were sensitive to group I, group II, or group V phages were sensitive to methicillin. Of the isolates that were sensitive to group III phages, 96% were methicillin resistant, and 70.5% of them were sensitive to phages 75 and 85.

Amikacin↗