Semiquantitative Culture Research Articles

Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns

This prospective study evaluated semiquantitative and qualitative catheter-culture methods for diagnosis of catheter-related infection (CRI) in newborns. Catheter tips from newborns admitted to the Neonatal Unit of the University Hospital of the Botucatu Medical School, UNESP were included in the study. Catheter cultures were performed with both semiquantitative and qualitative techniques. For CRI diagnosis, microorganisms isolated from catheter cultures and from peripheral blood cultures were identified and submitted to agent susceptibility test. The gold standard was the certain CRI diagnosis when same microorganism (specie and profile of susceptibility to agents) was isolated from both catheter tips and peripheral blood culture. A total of 85 catheters from 63 newborns were included in the study. The semiquantitative culture method, despite presenting lower sensitivity (90%), showed higher specificity (71%) when compared to 100% of sensitivity and 60% of specificity in the qualitative method. The identification of the microorganisms obtained from the catheter cultures showed a prevalence of coagulase-negative staphylococci (CNS) species. The specie Staphylococcus epidermidis (77.5%) was the prevalent in the catheters with positive semiquantitative cultures. Among 11 episodes with CRI diagnosis, 8 (72.7%) were associated with CNS species, of which 6 were S. epidermidis. Two episodes of CRI by S. aureus and one by Candida parapsilosis were also detected. The semiquantitative catheter-culture method showed advantages for CRI diagnosis in newborns when compared to the conservative qualitative method.

Evaluation of the Repertoire of the TonB‐Dependent Receptors ofHaemophilus ducreyifor Their Role in Virulence in Humans

Haemophilus ducreyi contains 3 TonB-dependent receptors: the hemoglobin receptor HgbA, which is required for virulence in humans; the heme receptor TdhA; and an uncharacterized conserved hypothetical protein TdX (HD0646). A double tdX/tdhA mutant (FX527) was constructed on the background of a human-passaged variant of strain 35000 (35000HP). Six volunteers were infected with 35000HP at 3 sites on one arm and with FX527 at 3 sites on the other. The pustule formation rate was 55.6% (95% confidence interval [CI], 35.7%-75.4%) at 18 parent-strain sites and 44.4% (95% CI, 15.0%-73.9%) at 18 mutant-strain sites (P = .51). Similar amounts of 35000HP and FX527 were recovered from pustules in semiquantitative culture. Thus, TdX and TdhA are not necessary for virulence, whereas HgbA is both necessary and sufficient for virulence in humans. The data suggest that hemoglobin is the sole source of heme/iron used by H. ducreyi in vivo and has implications for the potential of HgbA as a vaccine.

Cohort Study of the Pathogenesis and Molecular Epidemiology of Catheter-Related Bloodstream Infection in Neonates With Peripherally Inserted Central Venous Catheters

To better define the pathogenesis of catheter-related bloodstream infection (BSI) in neonates with peripherally inserted central venous catheters (PICCs) to guide the development of more effective strategies for prevention. Prospective nested cohort study. Level III neonatal intensive care unit in a community hospital. During a randomized trial to assess the safety and efficacy of a prophylactic vancomycin-heparin catheter-lock solution for the prevention of catheter-related BSI in neonates with PICCs, we performed cultures of peripheral and catheter-drawn blood samples, and quantitative cultures of catheter hub samples if BSI was suspected clinically. We performed semiquantitative cultures of the catheter tip and the catheter hub and the skin at the insertion site when the catheter was removed. Molecular subtyping by pulsed-field electrophoresis was used to determine the probable pathogenesis of all BSIs due to coagulase-negative staphylococci (CoNS); for BSIs caused by other microorganisms, epidemiologic concordance was based on speciation and antibiograms. Catheter-related BSI was considered extraluminally acquired if concordance was demonstrable solely between isolates recovered from the catheter tip and the blood, independent of concordance with isolates recovered from the insertion site. Catheter-related BSI was considered intraluminally acquired if concordance was demonstrated only between isolates recovered from the catheter hub and the blood. The source of the infection was considered indeterminate if both concordance patterns were present. Nosocomial BSI was identified in 23 of the 82 neonates in the cohort. Fifteen of these infections, 14 of which were caused by CoNS, were considered definite or probable catheter-related BSIs. Catheter-related BSI was intraluminally acquired in 10 (67%) of 15 patients, extraluminally acquired in 3 (20%), and indeterminate in 2 (13%). Most catheter-related BSIs in neonates with PICCs are caused by CoNS and derive from intraluminal contamination. Strategies for prevention of catheter-related BSI directed at this predominant mechanism of infection are most likely to be effective.

Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns

This prospective study evaluated semiquantitative and qualitative catheter-culture methods for diagnosis of catheter-related infection (CRI) in newborns. Catheter tips from newborns admitted to the Neonatal Unit of the University Hospital of the Botucatu Medical School, UNESP were included in the study. Catheter cultures were performed with both semiquantitative and qualitative techniques. For CRI diagnosis, microorganisms isolated from catheter cultures and from peripheral blood cultures were identified and submitted to agent susceptibility test. The gold standard was the certain CRI diagnosis when same microorganism (specie and profile of susceptibility to agents) was isolated from both catheter tips and peripheral blood culture. A total of 85 catheters from 63 newborns were included in the study. The semiquantitative culture method, despite presenting lower sensitivity (90%), showed higher specificity (71%) when compared to 100% of sensitivity and 60% of specificity in the qualitative method. The identification of the microorganisms obtained from the catheter cultures showed a prevalence of coagulase-negative staphylococci (CNS) species. The specie Staphylococcus epidermidis (77.5%) was the prevalent in the catheters with positive semiquantitative cultures. Among 11 episodes with CRI diagnosis, 8 (72.7%) were associated with CNS species, of which 6 were S. epidermidis. Two episodes of CRI by S. aureus and one by Candida parapsilosis were also detected. The semiquantitative catheter-culture method showed advantages for CRI diagnosis in newborns when compared to the conservative qualitative method.

Host–microbe interplay in persistent Staphylococcus aureus nasal carriage in HIV patients

It has been shown that persistent Staphylococcus aureus nasal carriage results in increased bacterial dispersal and a higher risk of infection compared to non-or-intermittent S. aureus carriage. Although many studies investigated S. aureus nasal carriage in HIV patients, none compared persistent carriage to non-persistent carriage nor were studies performed in the HAART era. We investigated the host–microbe interplay of persistent S. aureus nasal carriage in HIV-infected patients by studying host determinants of persistent carriage as well as the genetic structure of S. aureus strains isolated. We compared this genetic structure with the previously determined population structure of S. aureus isolates obtained from healthy individuals. Between February 2004 and June 2005 all HIV patients visiting the outpatient department of Erasmus MC (Rotterdam, The Netherlands) were asked to participate in this study. Participants were interviewed and screened for persistent S. aureus carriage using two semi-quantitative nasal swab cultures. For 443 patients two cultures were available, 131 (29.6%) were persistent carriers, which is significantly higher as compared to healthy individuals from the same geographic region (17.6%; P < 0.0001). Male sex (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.32–3.73), current smoking (OR, 0.58; 95% CI, 0.38–0.90), Pneumocystis jiroveci pneumonia (PCP) prophylaxis (OR, 0.39; 95% CI, 0.16–0.97) and antiretroviral therapy (OR, 0.61; 95% CI, 0.38–0.98) were independent determinants of persistent carriage. Only two strains were mecA positive (1.2%) and no PVL positive strains were detected. The population structure of S. aureus strains isolated from HIV patients appeared to be strongly overlapping with that of S. aureus isolates from healthy individuals.

A pilot safety and tolerability study of a non-hormonal vaginal contraceptive ring

To report preliminary data on the Ovaprene® device, a medical grade silicone ring that releases ferrous gluconate, ascorbic acid, and glycine in spermiostatic concentrations (Poly-Med Inc, Clemson University), designed for over the counter non-hormonal contraception. An open label short term pilot tolerability study in 20 paid volunteers. Women using another contraceptive method were eligible if they met the other inclusion criteria. Women were instructed in proper insertion of the ring at the completion of their menses, with removal at the onset of their subsequent menses or 29 days, whichever was shorter. PAP, vaginal cultures, colposcopy and post-coital testing were performed at daily to weekly follow-up. To date, 10 women have enrolled and 5 completed one cycle use (total observations approximately 100). All rings were inserted properly and retained in place including post-coitus (range 1–29 days). Patient questionnaire revealed no pain, bleeding or discharge. Male partners detected the device (2 partners of the 10 women). Wet mounts were normal. Semi-quantitative cultures showed no significant changes in genital flora. Vaginal pH was ≤4.5 except post-coitus (range 1–4 hours) was 4.5–6.5. All epithelium was intact. Random ferrous gluconate vaginal fluid concentrations during normal usage averaged 1438 ± 1028.93 μg/g. Post-coital test revealed sperm (motile/total, mean ct/10hpf) vaginal pool 2/>20; cervical mucous 0/0. One patient had odor for 24 hours after intercourse resolving spontaneously. All participants were willing to use and recommend the product during sexual intercourse in the future, as reported on the follow-up acceptability questionnaire. The Ovaprene® device is well tolerated and acceptable to sexually active women. Preliminary post-coital test demonstrates theoretical contraceptive efficacy. Additional data will be presented.

Correlation between early clinical response after catheter removal and diagnosis of catheter-related bloodstream infection

We conducted a retrospective post hoc analysis of prospectively collected data of cancer patients with central venous catheters (CVCs) who developed bacteremia with positive quantitative blood cultures (QBCs) drawn simultaneously through peripheral vein and CVC and which grew the same microorganisms from both blood cultures. We investigated whether clinical response of bacteremia, within 24, 48, or 72 h post-CVC removal, could be diagnostic of catheter-related bloodstream infection (CRBSI) when compared with microbiologic methods. Clinical response to antimicrobial therapy within 24 h of CVC removal in a patient with bacteremia was found to be highly suggestive of CRBSI, a finding that correlated well with semiquantitative catheter cultures and differential QBCs. However, response to antimicrobial therapy at ≥48 h after CVC removal was less likely to be diagnostic of CRBSI and could reflect a response to antimicrobial therapy irrespective of the source of the bloodstream infections.

A Randomized and Prospective Study of 3 Procedures for the Diagnosis of Catheter-Related Bloodstream Infection without Catheter Withdrawal

Suspicion of catheter-related bloodstream infection (CR-BSI) leads frequently to unnecessary catheter withdrawals, and many catheter-tip cultures yield negative results. The objective of this study was to compare the yield of 3 microbiological procedures to assess CR-BSI without catheter withdrawal. The study was prospectively performed in a group of patients without neutropenia or blood disorders who were admitted to the intensive care unit during a 37-month period with sepsis suspected on clinical grounds and who had central venous catheters inserted for >48 h. The microbiological procedures compared were semiquantitative cultures from hub and skin (superficial), differential quantitative blood cultures, and differential time to positivity between cultures of blood obtained from catheter hubs and peripheral blood. Of the 204 episodes of suspected CR-BSI included in the study, 28 were confirmed to be CR-BSI. We obtained the following results for sensitivity, specificity, positive and negative predictive values, and accuracy: superficial cultures, 78.6%, 92.0%, 61.1%, 96.4%, and 90.2%, respectively; differential quantitative blood cultures, 71.4%, 97.7%, 83.3%, 95.6%, and 94.1%, respectively; and differential time to positivity, 96.4%, 90.3%, 61.4%, 99.4%, and 91.2%, respectively. CR-BSI can be assessed without catheter withdrawal in patients without neutropenia or blood disorders who have catheters inserted for a short time and are hospitalized in the intensive care unit. Convenience, use of resources, and expertise should determine the technique of choice in different medical contexts. Because of ease of performance, low cost, and wide availability, we recommend combining semiquantitative superficial cultures and peripheral vein blood cultures to screen for CR-BSI, leaving differential quantitative blood cultures as a confirmatory and more specific technique.

Vacuum-assisted Closure for Wound Management

Vacuum-assisted Closure for Wound Management

Fourteen-day safety and acceptability study of the universal placebo gel

Objective This study evaluated the effect of the so-called universal placebo compared to the polystyrene sulfonate (PSS) placebo on genital irritation. Design A single-center, Phase I, randomized, closed-label study was performed to evaluate the genital irritation of microbicide placebo gels. Thirty healthy, sexually abstinent women were randomly assigned to apply 3.5 mL of either the universal placebo or the PSS placebo gel intravaginally twice daily for 14 days. Methods Genital irritation was assessed by signs as seen on pelvic examination and colposcopy and reports of symptoms. Vaginal health was assessed by wet mounts, Gram stains for Nugent score and polymorphonuclear leukocytes, and semiquantitative vaginal cultures. Acceptability was assessed as reported on the follow-up questionnaire. Results The universal placebo was less irritating than the PSS placebo with a lower proportion of women experiencing signs and/or symptoms of genital irritation throughout follow-up (36% compared to 80%, p=.0253). The universal placebo was associated with few and mild genital symptoms, few and minor colposcopic findings and good vaginal health with no clinically significant changes in genital flora. Most participants found the feel of the universal placebo gel neutral or pleasant, and all participants found it odorless. Conclusions The universal placebo appeared safe and acceptable when used twice daily for 14 days. The strategy of creating a de novo inert universal placebo is a successful approach. The universal placebo is appropriate for use as a placebo gel in HIV prevention trials with microbicide candidates.

Predictors of Mortality for Methicillin-Resistant Staphylococcus aureus Health-Care–Associated Pneumonia: Specific Evaluation of Vancomycin Pharmacokinetic Indices

The goal of this investigation was to determine whether vancomycin pharmacokinetic indexes (eg, serum trough concentrations or area under the concentration curve [AUC] values) were associated with mortality for patients with health-care-associated pneumonia (HCAP) attributed to methicillin-resistant Staphylococcus aureus (MRSA). A retrospective, single-center, observational cohort study. Barnes-Jewish Hospital, a 1,200-bed urban teaching facility. Adult patients requiring hospitalization who were identified as having HCAP attributed to MRSA by BAL semi-quantitative cultures. Retrospective data collection from automated hospital, microbiology, and pharmacy databases. One hundred two patients with MRSA HCAP were identified over a 6.5-year period. Thirty-two patients (31.4%) died during their hospitalization. The mean (+/- SD) vancomycin trough concentrations (13.6 +/- 5.9 vs 13.9 +/- 6.7 microg/mL, respectively; p = 0.866) and AUC values (351 +/- 143 vs 354 +/- 109 microg/h/mL, respectively; p = 0.941) did not differ between survivors and nonsurvivors. The stratification of the vancomycin trough concentrations and AUC values yielded no relationship with hospital mortality. We found no evidence that greater vancomycin trough concentrations or AUC values correlated with hospital outcome. Based on these results, aggressive dosing strategies for vancomycin (eg, trough concentrations of > 15 microg/mL) may not offer any advantage over traditional dose targets (range, 5 to 15 microg/mL).

Hub colonization of central line catheters in children with cancer

18530 Background: Central venous catheter (CVC) hub sites provide bacterial access to the blood stream through migration along the external and internal surfaces of the catheter. Hub colonization rates vary from 29–38% in the adult literature. While pediatric studies were not found, one study reported the incidence of blood stream infections in neonates to be 30 times higher in catheters with hub colonization compared to catheter hubs that were not colonized. The purpose of this descriptive study was to obtain baseline cultures of CVC hubs to determine the incidence of colonization. Methods: Fifty-one catheter hub cultures were obtained from a convenience sample of 27 children with cancer. The mean age of the patients was 8.2 years (range 0.5–16.2 years); 77% were diagnosed with leukemia and 23% with solid tumors. Cultures were obtained by swabbing the threaded area of the catheter hub after removing the injection cap. A semi-quantitative culture for bacteria and fungus was obtained using standard laboratory procedures by a microbiologist. This study was conducted in a large urban hospital in the Southwest. Results: Fifty-seven percent of the hubs were culture positive. Of those positive cultures, 69%, 24%, 10% and 7% were colonized with 2, 3, 4 and 5 organisms, respectively. The most common organism cultured was coagulase negative staphylococcus. The only significant risk factor for this population was previous central venous catheter infections (p = 0.025). Sixty-nine percent of the lines were tunneled catheters. Central venous catheters were in place on an average of 75.3 days but this was not a factor in the colonization rate. Conclusions: The majority (57%) of the 51 central venous catheter hubs cultured were colonized with at least one organism. This study is the first to evaluate the rate of central venous catheter hub colonization in children with cancer. These findings support the need for more stringent guidelines for central venous catheter care. Further research evaluating the relationship between hub colonization and subsequent blood stream infection is needed. No significant financial relationships to disclose.

High frequencies of antibody responses to CD4 induced epitopes in HIV infected patients started on HAART during acute infection

For many years only two human monoclonal antibodies (HMAbs) recognizing the CD4 induced (CD4i) epitopes of HIV-1 gp120 existed. Although a number of new CD4i HMAbs have been published recently, we have noted that in most attempts to produce HMAbs using EBV transformation a majority of antibodies produced in culture are lost within a few weeks. To determine what kinds of antibodies are made in these cultures we devised a semiquantitative culture to assess the frequency of B cells capable of producing antibodies and a microcompetition assay to determine what kinds of antibodies were made. Our results show that in three patients started on HAART during acute infection the most frequently produced antibodies binding to gp120 were directed against the CD4i epitopes. Our observations suggest that CD4i epitopes are much more immunogenic than had been previously appreciated. It is possible that envelope glycoproteins shed from virions and perhaps complexed with CD4 are responsible for eliciting these antibodies. The preservation of well regulated immune responses in these patients, together with repeated exposure to viral antigens (i.e. env), may explain the presence of larger than usual numbers of env-specific B cells that could be detected in EBV transformed cultures.

Assessment of cleaning and disinfection in S almonella-contaminated poultry layer houses using qualitative and semi-quantitative culture techniques

Salmonella infection of laying flocks in the UK is predominantly a problem of the persistent contamination of layer houses and associated wildlife vectors by Salmonella Enteritidis. Methods for its control and elimination include effective cleaning and disinfection of layer houses between flocks, and it is important to be able to measure the success of such decontamination. A method for the environmental detection and semi-quantitative enumeration of salmonellae was used and compared with a standard qualitative method, in 12 Salmonella-contaminated caged layer houses before and after cleaning and disinfection. The quantitative technique proved to have comparable sensitivity to the standard method, and additionally provided insights into the numerical Salmonella challenge that replacement flocks would encounter. Elimination of S. Enteritidis was not achieved in any of the premises examined although substantial reductions in the prevalence and numbers of salmonellae were demonstrated, whilst in others an increase in contamination was observed after cleaning and disinfection. Particular problems with feeders and wildlife vectors were highlighted. The use of a quantitative method assisted the identification of problem areas, such as those with a high initial bacterial load or those experiencing only a modest reduction in bacterial count following decontamination.

The value of Gram staining of catheter segments for rapid detection of peripheral venous catheter infections

Catheter-related bloodstream infections are common in hospitalized patients. Peripheral venous catheters (PVCs) are the most frequently used vascular access devices with usually low reported infection rates. We conducted a study to find the rate of PVC-related infections using semiquantitative (roll plate) and quantitative catheter culture techniques. We found significant growth in 9.5% of the PVCs by quantitative culture, which was predictive of a BSI in 43% of cases, which seems to be the major limitation of the method. We conclude that Gram stain is a fast and reliable diagnostic tool for rapid detection of PVC infection.

Role of bronchoalviolar lavage in pulmonary infections

It was aimed to evaluate the diagnostic utility of bronchoalve Veolar lavage (BAL) from cases of infiltrative diseases of lung admitted at Choithram Hospital & Re­search Centre, Indore (M.P.) during 2003 to 2004. The analysis included gram's staining, semi quantitative bacterial culture, AFB smear and culture, WBC and dif­ferential count and cytology. The gram's staining was found to have 83.6% sensitivity as compared to semi quan­titative culture. Colony count >10,000 / ml was considered as significant and 142 specimens yielded single organism while 56 had poly-microbial infections. Gram­negative bacilli like E.coli, Klebsiella spp. and Pseudomonas aeruginosa formed pyogenic infections. The analysis revealed pyogenic infections in 51%, tuberculosis in 21%, fungal in­fections in 12% and malignancy in 2% cases. Thus, the analysis of BAL specimen is valuable in the diagnosis of infiltrative disorders of lung.

Clinical relevance of Aspergillus isolation from respiratory tract samples in critically ill patients

IntroductionThe diagnosis of invasive pulmonary aspergillosis, according to the criteria as defined by the European Organisation for the Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG), is difficult to establish in critically ill patients. The aim of this study is to address the clinical significance of isolation of Aspergillus spp. from lower respiratory tract samples in critically ill patients on the basis of medical and radiological files using an adapted diagnostic algorithm to discriminate proven and probable invasive pulmonary aspergillosis from Aspergillus colonisation.MethodsUsing a historical cohort (January 1997 to December 2003), all critically ill patients with respiratory tract samples positive for Aspergillus were studied. In comparison to the EORTC/MSG criteria, a different appreciation was given to radiological features and microbiological data, including semiquantitative cultures and direct microscopic examination of broncho-alveolar lavage samples.ResultsOver a 7 year period, 172 patients were identified with a positive culture. Of these, 83 patients were classified as invasive aspergillosis. In 50 of these patients (60%), no high risk predisposing conditions (neutropenia, hematologic cancer and stem cell or bone marrow transplantation) were found. Typical radiological imaging (halo and air-crescent sign) occurred in only 5% of patients. In 26 patients, histological examination either by ante-mortem lung biopsy (n = 10) or necropsy (n = 16) was performed, allowing a rough estimation of the predictive value of the diagnostic algorithm. In all patients with histology, all cases of clinical probable pulmonary aspergillosis were confirmed (n = 17). Conversely, all cases classified as colonisation had negative histology (n = 9).ConclusionA respiratory tract sample positive for Aspergillus spp. in the critically ill should always prompt further diagnostic assessment, even in the absence of the typical hematological and immunological host risk factors. In a minority of patients, the value of the clinical diagnostic algorithm was confirmed by histological findings, supporting its predictive value. The proposed diagnostic algorithm needs prospective validation.

Choice of antibiotic for empirical therapy of acute cystitis in a setting of high antimicrobial resistance

A high prevalence of antimicrobial resistance among urinary isolates in the Garhwal region of Uttaranchal. To identify the most appropriate antibiotic for empirical treatment of community-acquired acute cystitis on the basis of local antimicrobial sensitivity profile. A prospective clinico-microbiological study including all clinically diagnosed patients with community acquired acute cystitis attending a tertiary care teaching hospital over a period of three years. Clean-catch midstream urine specimens, from 524 non-pregnant women with community-acquired acute cystitis, were subjected to semi-quantitative culture and antibiotic susceptibility by the Kirby- Bauer disc diffusion method. A survey was also conducted on 30 randomly selected local practitioners, to know the prevalent prescribing habits in this condition. The difference between the susceptibility rates of E. coli isolates to Nitrofurantoin and the other commonly prescribed antibiotics was analysed by applying the z test for proportion. 354 (67.5%) specimens yielded significant growth of E. coli.> 35% of the urinary E.coli isolates were resistant to the fluoroquinolones, which were found to be the most commonly used empirical antibiotics in acute cystitis. Resistance was minimum against Nitrofurantoin (9.3%, 33) and Amikacin (11.0%,39).> 80% of the fluoroquinolone-resistant strains were found to be sensitive to Nitrofurantoin. The best in vitro susceptibility profile in our study has been shown by Nitrofurantoin and a significantly high proportion of the urinary E. coli isolates have already developed resistance to the currently prescribed empirical antibiotics, viz. the fluoroquinolones. In view of these in vitro susceptibility patterns, a transition in empirical therapy appears imminent.

Bacteremia caused by the novel species Mycobacterium canariasense

Several rapidly growing mycobacteria (RGM) species have been described as etiologic agents of bacteremia in cancer patients with long-term central devices [1–5].We report here a series of cases of bacteremia caused by the novel species of RGM namedM. canariasense that were identified through a retrospective review of all cases in which at least one blood culture was positive for M. canariasense at a tertiary care hospital. Blood cultures performed using Bactec Vial–Aerobic Cultures (Becton–DickinsonMicrobiology Systems, Sparks, MD, USA) were incubated for a maximum of 15 days. Species assignation was done according to phenotypic and genotypic characteristics [6]. The agar disk elution method [7] was used to determine the susceptibility of the isolates to amikacin, tobramycin, imipenem, doxycycline, cefoxitin, and ciprofloxacin, and the E test (AB Biodisk, Solna, Sweden) [1] was used to test susceptibility to clarithromycin. The medical records of all patients from whom M. canariasense was isolated were examined, and clinical and microbiological data were obtained from their medical charts. A clinically significant case of bacteremia was defined when the following criteria were met: (a) presence of clinical symptoms such as fever (oral temperature of >38°C), chills or hypotension of acute onset at the time the blood specimens were taken; and (b) absence of another infectious cause that could explain the clinical symptoms. Definite catheter-related bacteremia was defined using the following criteria outlined previously by Raad et al. [2]: (a) clinical (or autopsy) and microbiological data disclosed no source of bacteremia other than the catheter; and (b) the same Mycobacterium species was recovered from the catheter tip (i.e., >15 cfu/catheter segment was recovered using the roll-plate semiquantitative culture technique). Probable catheter-related bacteremia was diagnosed if only the first criterion was fulfilled, and relapse was diagnosed when the same Mycobacterium species was isolated and clinical symptoms recurred after the end of therapy. To analyze concordance between the clinical classifications made according to the above criteria and the outcome of the clinical evaluation performed by the patient’s doctor (as reflected in the clinical chart), the Kappa index was measured; K>0.75 was considered excellent. The review identified 17 cases in which M. canariasense was isolated from blood between January 2000 and September 2002; in ten of these cases more than one blood culture was positive. Blood specimens were obtained via the indwelling catheters in all cases in which the drawing procedure was specified. Mycobacteria grew after the standard incubation period of 5 days in the blood culture bottles of 11 patients, and they were not isolated from any clinical specimens other than the blood or the catheter tip. All strains showed susceptibility to all antibiotics tested. M. canariasense was considered the etiologic agent of bacteremia in 12 of the 17 cases. The main characteristics of the patients are shown in Table 1. Eleven patients had received chemotherapy previously, eight had received transfusions, six were neutropenic, three had undergone bone marrow transplantation, three had received steroid therapy, and two had received parenteral nutrition. None of the patients had clinical evidence of tissue invasion. All 12 M. I. Campos-Herrero (*) . D. Garcia . P. Suarez Servicio de Microbiologia, Hospital Universitario de Gran Canaria Dr. Negrin, Barranco de la Ballena s/n, 35020 Las Palmas de Gran Canaria, Canary Islands, Spain e-mail: mcamnavl@gobiernodecanarias.org Tel.: +34-928-449518 Fax: +34-928-449292

Rapid Screening of Urine Specimens for Bacteriuria by the Cellenium System

This study evaluated the performance of the Cellenium 160 US urine screening system in comparison to that of the semiquantitative culture method. The performance characteristics of the Cellenium system for all clinically significant uropathogens were 89.5% sensitivity, 94.4% specificity, 97.1% negative predictive value, and 81% positive predictive value.