Revision rates after total joint replacement: cumulative results from worldwide joint register datasets.

In a systematic review, reports from national registers and clinical studies were identified and analysed with respect to revision rates after joint replacement, which were calculated as revisions per 100 observed component years. After primary hip replacement, a mean of 1.29 revisions per 100 observed component years was seen. The results after primary total knee replacement are 1.26 revisions per 100 observed component years, and 1.53 after medial unicompartmental replacement. After total ankle replacement a mean of 3.29 revisions per 100 observed component years was seen. The outcomes of total hip and knee replacement are almost identical. Revision rates of about 6% after five years and 12% after ten years are to be expected.

[Detection of inferior products in arthroplasty and implementation of findings: a retrospective analysis of the Boneloc incident]. / Erfassung von minderwertigen Produkten in der Endoprothetik und Umsetzung der Erkenntnisse: eine retrospektive Analyse am Beispiel des Boneloc-Knochenzements.

AIM: By a retrospective assessment of the Boneloc incident, a bone cement which had an inferior outcome in terms of survival rate, the value of published datasets for the detection of inferior outcomes was evaluated. METHOD: A structured literature review of English and German peer reviewed journals was conducted. The articles were assessed with respect to revision rate and statements about the product. In a standardised methodology, adjusted for number of cases and follow-up period, the revision rate was calculated. Main goal was to assess the agreement of published information from different datasets. RESULTS: In the first 4 years after Boneloc had been brought on the market exclusively experimental studies were published, most of which were in favour of the product. In 1995, clinical studies, migration analyses and register-based articles were published. Most of them reported about inferior results, in the same year Boneloc was taken from the market worldwide. Sample-based clinical follow-up studies were not able to contribute to the decision-making process, they were published with a delay of several years and were underpowered from a statistical point of view. All of them published critical statements--after the product had no longer been available on the market for many years. The average revision rate in sample-based studies exceeded the reference value in the Norwegian Arthroplasty Register 7.35-fold. When the inferior results with Boneloc were published, the product had already disappeared from the national markets in Scandinavian countries' operating registers. The central position of orthopaedic scientific societies in the entire outcome monitoring system in these countries seems to be a key factor for success and rapid reaction to identified problems. CONCLUSION: Arthroplasty registers and migration analyses have the highest value for the rapid and reliable detection of inferior outcomes in comparative analyses of published articles. Experimental studies did not agree with the performance of the product in a retrospective view, the data cannot be transferred from the estimation of future clinical outcome like survival rates. The involvement of scientific societies in the assessment and dissemination of the results is a key factor to realise potential benefit by an advanced quality monitoring project like arthroplasty registers.

Confirming positive results of nucleic acid amplification tests (NAATs) for Chlamydia trachomatis: all NAATs are not created equal.

The Centers for Disease Control and Prevention recommended confirming positive screening tests for Chlamydia trachomatis when positive predictive values are <90%. It is accepted that less sensitive tests (i.e., culture and immunoassays) should not be used to confirm the results of more sensitive nucleic acid amplification tests (NAATs). We show that the same principle applies when NAATs are used for confirmation.

Brevibacterium casei bacteremia and line sepsis in a patient with AIDS.

Brevibacteria are obligately aerobic gram-positive bacilli that are associated with milk products and are also found on human skin. Strains of Brevibacterium casei have been found to correspond to Centers for Disease Control coryneform groups B-1 and B-3 and have been isolated from a variety of human clinical specimens. In this report, we describe a case of B. casei bacteremia and sepsis in a patient with AIDS associated with a contaminated Hickmann catheter and review the microbiology and characteristics of these emerging opportunistic pathogens.

Evaluation of the BactiCard Neisseria for identification of pathogenic Neisseria species and Moraxella catarrhalis.

The BactiCard Neisseria (Remel, USA) is a chromogenic enzyme substrate system for identifying Neisseria gonorrhoeae, Neisseria meningitidis, Neisseria lactamica, and Moraxella catarrhalis. The identification system consists of a card with four test circles impregnated with chromogenic substrates for indoxyl butyrate esterase (IB), prolyl aminopeptidase (PRO), gamma-glutamyl aminopeptidase (GLUT), and ss-galactosidase (BGAL). These substrates permit the identification of Moraxella catarrhalis, Neisseria gonorrhoeae, Neisseria meningitidis, and Neisseria lactamica, respectively. After hydration of the circles with buffer, colonies from growth on selective media or a subculture are applied to the four circles. IB and BGAL reactions are read for a blue-green color after 2 and 15 min, respectively. PRO and GLUT reactions are read at 15 min for a red color after addition of a developer reagent. Identifications obtained with the BactiCard Neisseria were compared with those obtained using conventional procedures for 558 isolates in a blinded fashion. The BactiCard Neisseria identified 100% of 254 Neisseria gonorrhoeae, 100% of 125 Neisseria meningitidis, 53 (98.2%) of 54 Neisseria lactamica, and 123 (98.4%) of 125 Moraxella catarrhalis isolates. The BactiCard Neisseria is an accurate and rapid system for identification of these microorganisms in the clinical laboratory.

Citrobacter sedlakii meningitis and brain abscess in a premature infant.

Citrobacter sedlakii was isolated from blood and cerebrospinal fluid cultures of a 5-day-old premature infant with sepsis, meningitis, and brain abscess. This newly described organism was difficult to identify due to discrepancies between the Vitek and API 20E identification systems. To our knowledge, this is the first report of the isolation of C. sedlakii from cerebrospinal fluid.

Immune complex-dissociated p24 antigen in congenital or perinatal HIV infection: role in the diagnosis and assessment of risk of infection in infants.

Immune complex-dissociated (ICD) HIV-1 p24 antigen assay is a rapid technique for assessing the presence of HIV gag or core protein in plasma or serum. In this study, ICD p24 antigen detection in HIV-1 infected mothers and their infants enrolled in the Women and Infants Transmission Study (WITS) was evaluated primarily as a diagnostic assay for HIV-1 detection in young infants and for its association with perinatal transmission. Plasma from 47 infected infants and 160 uninfected infants was examined, along with plasma from 197 of their mothers who had a delivery or close-to-delivery specimen. ICD p24 antigen was detected in plasma of 27.3% of infected infants at birth and in 70% to 81% at 1 to 6 months. The diagnostic specificity at birth was 90% and 98% to 100.0% at 1 to 6 months. The ICD p24 antigen concentration correlated with concurrent quantitative HIV culture results. The risk of transmission from mother to infant was higher if the mother had detectable ICD p24 antigen at or near the time of delivery (p = 0.002), but its presence did not accurately predict transmission (positive predictive value of 36%, negative predictive values of 85%). The relative ease of performing the ICD p24 antigen assay and the low cost compared with that of HIV culture or DNA PCR makes this test a useful adjunct for the diagnosis of perinatal HIV infection and for enhancing understanding of its pathogenesis, particularly where cost and availability limit access to more sensitive assays.

Catalase activity as a predictor of amniotic fluid culture results in preterm labor or premature rupture of membranes.

OBJECTIVE: To evaluate catalase activity as a rapid predictor of microbial invasion of amniotic fluid (AF). METHODS: The study population consisted of 74 patients before 36 weeks' gestation with preterm labor or premature rupture of membranes (PROM). Subjects were excluded if there was evidence of clinical chorioamnionitis or fetal distress at admission. Amniocentesis was done within 24 hours of admission, and the AF was cultured for aerobic and anaerobic bacteria and for Mycoplasma species. All AF samples were Gram stained, and slides were examined by microbiology technologists. Amniotic fluid catalase activity was measured immediately after amniocentesis using a commercially available kit. The sensitivity of the Gram stain and catalase activity were compared using McNemar exact test. RESULTS: Amniotic fluid cultures were positive in 12 of 37 (32%) patients presenting with preterm labor and in 21 of 37 (56%) patients with PROM. Catalase activity was significantly more sensitive than Gram stain in detecting positive AF cultures in cases of PROM (P < .001) and preterm labor (P < .04). CONCLUSION: Catalase activity is a simple, rapid test that is useful in identifying subclinical intra-amniotic infection in patients with preterm labor or PROM.

Unexpected isolation of Bordetella pertussis from a blood culture.

Bordetella pertussis was isolated from a culture of blood from a 31-year-old man with Wegener's granulomatosis. The organism was detected with the BACTEC 9240 system after 6 days of incubation and was confirmed as B. pertussis by the Centers for Disease Control and Prevention. To our knowledge, this is the first published report of the recovery of B. pertussis from blood.

Evaluation of RapiDEC Staph for identification of Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus.

RapiDEC Staph is a test for presumptive identification of the principal human staphylococcal species, Staphylococcus aureus, S. epidermidis, and S. saprophyticus. The test includes control and test cupules for fluorogenic detection of coagulase and chromogenic substrates for alkaline phosphatase and beta-galactosidase. These tests identify S. aureus, S. epidermidis, and S. saprophyticus, respectively. Positive results with both chromogenic substrates provide a presumptive identification of S. xylosus or S. intermedius (S. xylosus-S. intermedius). Test cupules are inoculated with an organism suspension, and reactions are read after a 2-h incubation. RapiDEC-Staph was evaluated with 303 clinical and stock staphylococcal strains. Identifications were compared with those obtained by the tube coagulase test, a latex slide coagulase test (StaphAUREX), another commercial identification system (Staph-TRAC), and additional conventional tests. RapiDEC-Staph correctly identified 100% of 130 S. aureus strains, 70.3% of 74 S. epidermidis strains, and 81.3% of 32 S. saprophyticus strains. Four of five S. xylosus isolates were called S. xylosus-S. intermedius. Unidentified S. epidermidis and S. saprophyticus strains were called "Staphylococcus spp." Among the 62 other coagulase-negative staphylococci, 4 were misidentified as S. epidermidis and 7 were misidentified as S. saprophyticus. While the sensitivity and specificity of the fluorogenic coagulase test for S. aureus were 100%, failure to detect alkaline phosphatase activity in several S. epidermidis isolates resulted in fewer correct identifications by the RapiDEC-Staph test for this species.

In vitro study of amniotic fluid gram stain: effect of centrifugation.

OBJECTIVE: Gram stain of amniotic fluid (AF) is used to detect intraamniotic infection. The purpose of this study was to determine if centrifugation improved the ability of AF Gram stain to detect bacteria. METHODS: AF obtained by amniocentesis from patients with preterm labor (PTL) or preterm premature rupture of membranes (PPROM) was pooled. Individual AF samples as well as the pooled sample had a negative Gram stain for microorganisms or white blood cells (WBCs) and negative cultures. With pure bacterial cultures, a suspension equivalent to a 0.5 McFarland turbidity standard was prepared and then serially diluted in the AF to either 10(6), 10(5), 10(4), or 10(3) colony forming units (cfu)/ml. Each sample was divided into 2 equal portions, with 1 undergoing centrifugation. The Gram stains were interpreted by technologists in the clinical microbiology laboratory in a blinded fashion. Fisher's exact test was used to compare the bacterial detection rate in centrifuged vs. uncentrifuged AF samples at each concentration. RESULTS: Centrifugation of AF significantly improved the ability of the Gram stain to detect bacteria at bacterial concentrations < or =10(4) cfu/ml (P < 0.01). At concentrations > or =10(5) cfu/ml, centrifugation did not improve the ability of the Gram stain to dtect bacteria. CONCLUSIONS: At low bacterial concentrations, centrifugation of AF increases the bacterial detection rate of AF Gram stain.

Asymptomatic Neisseria subflava biovar perflava bacteriuria in a child with obstructive uropathy.

A case of asymptomatic urinary tract infection with Neisseria subflava biovar perflava in a 10-year-old male patient with congenital structural abnormalities of the urinary bladder is presented. The organism was recovered from three catheter urine specimens collected over a seven-month period. A brief review of the role of saprophytic Neisseria species in infectious processes is presented and the likely source of this unusual urinary tract isolate is discussed.

Comparison of monoclonal antibody methods and a ribosomal ribonucleic acid probe test for Neisseria gonorrhoeae culture confirmation.

Recently, a chemiluminescent nucleic acid probe test that specifically detects the ribosomal ribonucleic acid of Neisseria gonorrhoeae has been released for clinical laboratory use (AccuProbe Neisseria gonorrhoeae). In this study, three coagglutination tests (GonoGen I, Meritec GC, and GC Omni), the GonoGen II immunofiltration method and the Micro Trak Neisseria gonorrhoeae fluorescent monoclonal antibody test were compared with AccuProbe for identification of gonococci. Strains tested (n = 376) included 194 Neisseria gonorrhoeae, 82 Neisseria meningitidis, 32 Neisseria lactamica, 32 Neisseria species, 32 Moraxella catarrhalis, 2 Moraxella spp. and 2 Kingella denitrificans. The GonoGen I, Meritec GC and GC Omni coagglutination tests produced clearly positive results for 93.8%, 92.3% and 95.9% of the gonococci, respectively. The GonoGen II unequivocally identified 91.8% and the MicroTrak fluorescent antibody test identified 90.7% with 2+ or greater fluorescence. AccuProbe identified 100% of the gonococci tested. GonoGen I and GonoGen II were 98% specific, Meritec GC was 99% specific and the specificity of the GC Omni, MicroTrak fluorescent antibody and AccuProbe tests was 100%. While antibody-based tests were reliable when results were clearly interpretable, the AccuProbe was the only confirmatory test that was 100% accurate. Serotyping studies indicate that an array of beta-lactamase positive and negative gonococcal serotypes fail to react with the monoclonal antibody-based tests in general and with the fluorescent antibody test in particular.

Negative images of mycobacteria in aspiration biopsy smears from the lymph node of a patient with acquired immunodeficiency syndrome (AIDS): report of a case and a review of the literature.

Negative images of acid-fast bacilli were observed in Diff-Quik-stained smears of lymph node aspirates from a patient with acquired immunodeficiency syndrome (AIDS) and disseminated Mycobacterium avium-intracellulare infection. The significance of this finding in relation to the diagnosis and treatment of this infection is discussed and the literature pertaining to this observation is reviewed.

B.CAT CONFIRM, a rapid test for confirmation of Branhamella catarrhalis.

B.CAT CONFIRM (Scott Laboratories, Inc., Fiskeville, R.I.), a rapid test for detection of tributyrin hydrolysis, was evaluated for its ability to identify strains of Branhamella catarrhalis and to differentiate them from Neisseria species and related species. On initial testing, B.CAT CONFIRM was positive for 65 (96%) of 68 B. catarrhalis strains within 30 min after inoculation. Retesting of the remaining three strains resulted in their correct identification. B.CAT CONFIRM was negative for all Neisseria spp. (130 strains) and for Kingella spp. (3 strains). Two of the three Moraxella spp. were weakly positive in the B.CAT CONFIRM after 60 min, but these reactions were easily distinguishable from the strong reactions of B. catarrhalis strains. This test will be helpful in the clinical laboratory for the rapid identification of B. catarrhalis in clinical specimens.

Identification of Neisseria spp., Haemophilus spp., and other fastidious gram-negative bacteria with the MicroScan Haemophilus-Neisseria identification panel.

The Haemophilus-Neisseria identification (HNID) panel (American MicroScan, Sacramento, Calif.) is a 4-h microdilution format system for identification of Haemophilus and Neisseria spp., Branhamella (Moraxella) catarrhalis, and Gardnerella vaginalis. The HNID panel was evaluated by using 423 clinical isolates and stock strains of these organisms, and HNID identifications were compared with those obtained by conventional methods. In addition, 32 isolates representing six genera not included in the HNID data base were tested to determine whether these organisms would produce unique biotype numbers for possible inclusion in the data base. The HNID panel correctly identified 95.3% of 86 Neisseria gonorrhoeae strains, 96% of 25 G. vaginalis strains, and 100% of 28 Neisseria lactamica strains and 48 B. catarrhalis strains. Only 64.7% of 68 Neisseria meningitidis isolates were identified correctly owing to false-negative or equivocal carbohydrate and/or aminopeptidase reactions. Among the Haemophilus spp., 98.8% of 83 H. influenzae strains, 97.1% of 34 H. parainfluenzae strains, and 80% of 15 H. aphrophilus and H. paraphrophilus strains were correctly identified. Eight strains of Neisseria cinerea, a species not included in the data base, produced profiles identical with those for B. catarrhalis and N. gonorrhoeae. Isolates of other species not included in the data base, including Eikenella corrodens, Kingella spp., and Cardiobacterium hominis, produced unique biochemical reaction patterns on the panel. Modification of interpretative criteria for certain tests, expansion of the data base to include other species, and suggestions for additional confirmatory tests will increase the accuracy and utility of the HNID panel.

Osteomyelitis caused by Rhodococcus equi in a renal transplant recipient.

We report the first case of osteomyelitis due to Rhodococcus equi, which occurred in a renal transplant patient. Infection with this organism is rare and usually causes a distinct clinical syndrome resembling pulmonary tuberculosis. We investigated by time-kill curve analysis various antimicrobial combinations for in vitro efficacy. The literature is briefly reviewed, and aspects of diagnosis and therapy are discussed.

Evaluation of a ten-minute chromogenic substrate test for identification of pathogenic Neisseria species and Branhamella catarrhalis.

A ten-minute chromogenic substrate test was evaluated for its ability to rapidly identify pathogenic Neisseria spp. and Branhamella catarrhalis. Identifications obtained with this system were compared to those obtained using conventional procedures. The test correctly identified 98.9% of 90 Neisseria gonorrhoeae, 98.3% of 60 Neisseria meningitidis, 96.2% of 26 Neisseria lactamica, and 100% of 36 Branhamella catarrhalis strains. Eight Neisseria subflava strains that grew on modified Thayer-Martin agar were prolyl aminopeptidase positive and were misidentified as Neisseria gonorrhoeae. Other strains of saprophytic Neisseria spp. also reacted with the chromogenic substrates. The system was accurate and reliable for identifying the commonly encountered pathogenic species. In light of recent reports describing new species and atypical Neisseria strains, however, careful attention to the salient features of both common and atypical organisms is necessary for proper use of rapid enzymatic identification tests.

Clinical evaluation of the Vitek ANI card for identification of anaerobic bacteria.

An evaluation of the Vitek Anaerobe Identification (ANI) card was performed with 341 bacterial isolates, including 313 clinical isolates and 28 stock strains of anaerobic microorganisms. Identifications obtained with the ANI card were compared with those determined by conventional methods. The card identified 73.2% of 149 anaerobic gram-negative bacilli, 63.6% of 44 Clostridium spp., 65.8% of 38 anaerobic nonsporeforming gram-positive bacilli, and 69.1% of 110 anaerobic cocci, with no further testing required. When genus-level identifications were included, 83.9% of the anaerobic gram-negative bacilli, 70.5% of Clostridium spp., 73.7% of the anaerobic nonsporeforming gram-positive bacilli, and 73.6% of the anaerobic cocci were identified. Nineteen isolates (5.6%) produced identifications of good confidence but marginal separation or questionable biotype, in which the correct identification was listed with one or two other possible choices and extra tests were required and suggested. A total of 28 (8.2%) were not identified and 29 isolates (8.5%) were misidentified by the ANI card. Among the commonly isolated clinically significant anaerobes, the ANI card identified 100% of 55 Bacteroides fragilis and 100% of 8 Clostridium perfringens. Use of supplemental tests and expansion of the data base to include additional strains of organisms that are difficult to separate even with conventional methods may improve the accuracy of the ANI card as a method for identification of anaerobic bacteria in the clinical laboratory.