Pediatric Blood Culture Bottles Research Articles

Pitfalls of a Multiplex PCR Panel for Identification of Bloodstream Pathogens.

We evaluated the diagnostic performance of the FilmArray Blood Culture Identification Panel (BCID; bioMerieux) for the detection of bloodstream pathogens. From May to August 2022, up to 67 samples from positive blood cultures previously processed with BACTEC FX (BD) were collected and submitted to the BCID panel. BCID panel results were compared with traditional culture results. We tested 67 positive blood culture samples; 13 samples were from pediatric bottles of BACTEC Peds Plus/F media (BD). The overall sensitivity of the BCID panel was 89.9% (62/69; 95% CI, 80.2 - 95.3%). For blood-stream pathogens targeted by the BCID panel, sensitivity was 98.4% (62/63; 95% CI, 90.7 - > 99.9%). Interestingly, Proteus species were additionally detected in 6 samples from pediatric blood culture bottles. BCID demonstrated high clinical sensitivity for target pathogens, but positive findings for unexpected multiple targets or Proteus species require cautious interpretation to avoid false positives.

P167 Fungemia in neonatal ICU of a pediatric hospital in NE India

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PM ObjectivesTo determine the prevalence of fungemia in a neonatal intensive care unit (NICU) during a period of 4 years and 4 months (January 2018 to April 2022) and to identify the causative fungal pathogens and analyze the associated risk factors.MethodsA retrospective study was conducted by collecting records of neonatal fungemia occurring in 17 bedded NICU of Mother's Care Children Hospital and Research Centre, Imphal. Cases were identified by searching of computerized microbiology blood culture database. Blood cultures were carried out using automated BacT/ALERT(Biomerieux). Whenever flagged positive, immediate gram staining and subculture were carried in Blood agar, SDA, and MacConkey agar. The isolates were identified by their morphology, germ tube test, and biochemical test in VITEK-2 (Biomeriux) system. Antifungal susceptibility testing too was carried out in VITEK-2.ResultsA total of 2621 blood samples in pediatric blood culture bottles were received from NICU during this period of 4 years and 4 months. 21 samples showed growth of yeast cells. The isolates include Candida parapsilosis (10), C. albicans (7), Wickerhaemomyces anomalas (3), and C. krusei (1). Low birth weight, premature rupture of membrane, antibiotic therapy, and prolonged hospital stay were main risk factors. Majority of the neonates recovered with antifungal treatment.Conclusion Candida parapsilosis was isolated with highest frequency. Fungemia is more common in low birth weight babies.

Preterm Infant with Respiratory Distress, Hypotonia, and Hypoglycemia.

Preterm Infant with Respiratory Distress, Hypotonia, and Hypoglycemia.

Performance and Impact on Initial Antibiotic Choice of Direct Identification of Pathogens from Pediatric Blood Culture Bottles Using an In-House MALDI-TOF MS Protocol.

ABSTRACTThe performance and early therapeutic impact of direct identification by matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI-TOF; DIMT) on pediatric blood culture bottles using in-house-developed methods to obtain microbial pellets for spectrometric analysis have seldom been studied. During a 2-year period (June 2018 to May 2020), DIMT was performed on broths from positive pediatric blood culture bottles using an in-house-developed method. Organism identifications with a score of ≥1.6 were notified to treating clinicians. Therapeutic modifications that occurred after the communication of DIMT were reviewed through the electronic medical records. DIMT was performed on 530 pediatric positive blood culture bottles. Among 505 monomicrobial bottles, identifications from 298 (97.7%) deemed as bloodstream infections (BSI) and 189 (94.5%) as contaminations had DIMT notified to clinicians. All identifications were correct except for one Streptococcus mitis incorrectly reported as Streptococcus pneumoniae. Therapy modifications resulting from DIMT occurred in 27 (8.3%) patients with BSI. Deescalation from effective or ineffective broad-spectrum regimens occurred mainly in Enterococcus faecalis bacteremia, whereas appropriate escalation from an ineffective regimen with narrower spectrum occurred mainly in bacteremia caused by AmpC-β-lactamase-producing Enterobacterales. Escalation therapy was instituted significantly faster than deescalation therapy (median time, 0.75 versus 10.5 h [P = 0.01]). DIMT also enabled clinicians to confirm contamination in nearly one-half of patients with contaminated blood cultures. Our DIMT method applied to positive pediatric blood culture bottles demonstrated reliable performance for the rapid identification of pathogens. Our DIMT approach allowed therapeutic optimization in BSI, especially involving microorganisms with intrinsic antibiotic resistance, and was helpful in the early identification of likely contaminants.IMPORTANCE We demonstrate the performance and early impact on the antimicrobial management of bloodstream infections of an inexpensive, in-house preparation method for direct identification of bloodstream pathogens in pediatric blood culture bottles by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry.

Comparison of Microorganism Detection and Time to Positivity in Pediatric and Standard Media from Three Major Commercial Continuously Monitored Blood Culture Systems.

New blood culture instrumentation and medium formulations have led to improved time to positivity (TTP) for positive blood cultures. Data regarding the necessity of pediatric blood culture bottles with contemporary blood culture systems are sparse. We compared performance of three commercial blood culture systems, evaluating impact of blood volumes in standard and pediatric blood culture media across systems. Simulated blood cultures with packed red blood cells (PRBCs) and three Gram-positive, four Gram-negative, and one anaerobic organism (final concentrations ranging from 0.5 to 19 CFU/ml blood) on the Virtuo, VersaTrek, and Bactec FX instruments were evaluated with FAN Plus, Redox, and Bactec Plus media, respectively. For each medium/instrument/organism combination, 1-, 3-, 5-, and 10-ml blood volumes were evaluated in triplicate. Detection rate was not affected by blood volume. Aerobic organisms that demonstrated variable rates of detection were Kingella kingae, Haemophilus influenzae, and Neisseria meningitidis. Bacteroides fragilis was detected in 83%, 100%, and 100% of Virtuo, VersaTrek, and Bactec anaerobic bottles, respectively. The average TTP of standard medium for aerobic organisms detected on Virtuo was decreased compared to those for VersaTrek (-2.3 h) and Bactec (-4.9 h). Compared to standard medium, detection rate and TTP were unchanged on Virtuo, while TTP was reduced with pediatric medium for 2/8 organisms tested on Bactec and 7/8 organisms on VersaTrek, illustrating the potential benefit of pediatric medium on VersaTrek or Bactec when low blood volumes (<5 ml) are collected. These results demonstrate that TTP is decreased on the Virtuo compared to VersaTrek and Bactec for many microorganisms associated with bloodstream infection (BSI) but may have species-specific limitations.

Lack of Detection of Haemophilus influenzae Using Adult Blood Culture Bottles Inoculated at Low Volumes.

Based on guidelines from the Infectious Diseases Society of America and the American Society for Microbiology, many pediatric hospitals are implementing weight-based collection guidelines for blood cultures. To simplify the process of culture collection, there has been interest in validating the use of adult blood culture bottles with low volumes, which may allow for a "one size fits all" bottle. This study examined 9 clinically relevant organisms (Staphylococcus aureus, Streptococcus pneumonia, Streptococcus agalactiae, Enterococcus faecium, Escherichia coli, Haemophilus influenzae, Pseudomonas aeruginosa, Candida glabrata, and Candida albicans) utilizing the BD BacTec system at various inoculation volumes and dilutions to assess performance, based on time to positivity, of adult blood culture bottles compared with pediatric blood culture bottles. There was a lack of detection of H. influenzae using adult blood culture bottles inoculated at low volumes, whereas pediatric bottles detected H. influenzae regardless of dilution-volume combinations tested. Exclusive use of adult blood culture bottles may not detect H. influenzae bacteremia in the setting of low-volume inoculum.

Specific PCR and Quantitative Real-Time PCR in Ocular Samples from Acute and Delayed-Onset Postoperative Endophthalmitis

Rapid identification of virulent pathogens is essential to strengthen the therapeutic strategy of acute endophthalmitis. This study sought to compare the contribution of a combination of polymerase chain reaction (PCR)-based tests to culture methods, in patients with postoperative endophthalmitis. Prospective multicenter study diagnostic evaluation. Setting: university referral centers. 153 consecutive patients presenting with acute or delayed-onset postoperative endophthalmitis, between 2008 and 2015. There were a total of 284 aqueous humor (AH) and/or vitreous fluid (VF) samples. Outcomes and measurements: microbiological tests of intraocular samples included bacterial culturing of pediatric blood culture bottles; 16SrDNA amplification and sequencing (panbacterial PCR) for detection and identification of all bacterial species; real-time PCR (qPCR) assays targeting the femA or lytA gene for detection of Staphylococcus aureus (S. aureus) or Streptococcus pneumoniae (S. pneumoniae), respectively; and a qPCR assay targeting the tuf gene for detection and quantification of Staphylococcus epidermidis (S. epidermidis). At the time of admission, the rate of detection of microorganisms by PCR-based tests was not significantly different than that by culturing (38% versus 30% in AH samples [n= 69]; 66% versus 63% in VF samples [n= 82], respectively). In contrast, after 1 intravitreal injection (IVI) of antibiotics, the identification rate by PCR-based tests was higher than that in VF by culturing (62% vs 48%, respectively; n= 94; P= 0.05). Bacteria were identified in 70% of patients, with a predominance of Gram-positive bacteria (93%). Specific qPCR tests targeting S. aureus and S. pneumoniae did not provide additional diagnoses but provided earlier results. The S. epidermidis load in vitreous at the time of patients' admission was higher in cases of final visual acuity (VA) of <20/40 (127,118 ± 125,848 DNA copies/mL) in patients with a VA of ≥20/40 (40350,000 ± 46,912 DNA copies/mL; P= 0.09). No significant changes in S. epidermidis load was found after one IVI. Patients with acute or delayed-onset endophthalmitis should benefit from microbiological identification in vitreous samples by combined analysis using bacterial cultures in pediatric blood culture bottles and panbacterial PCR. The last test was more effective than cultures in vitreous samples collected after an IVI of antibiotics. The qPCR tests targeting S. aureus and S. pneumoniae gave earlier results than culture and panbacterial PCR but did not provide additional diagnoses. As for S. epidermidis infections, determination of bacterial load using the qPCR test targeting the tuf gene could help evaluation of the visual prognosis of patients. Its role in the follow-up of patients after antibiotic treatment needs further investigation.

2019 J. Leonard Goldner Award Winner: A Novel Intraoperative Technique Seeding Morselized Bone Tissue into Pediatric Blood Culture Bottles Improves Microbiological Diagnosis in Patients with Foot and Ankle Osteomyelitis

Category:Basic Sciences/Biologics, DiabetesIntroduction/Purpose:Bone infection in the foot is a challenging pathology that frequently leads to amputation and major disability. Agent identification and antimicrobial susceptibility-guided therapy is the key for a successful treatment. Standard culture methods for bone tissue have demonstrated poor sensitivity. It has been reported that synovial fluid culture sensitivity is enhanced when seeded into pediatric blood culture bottles (PBCB), however, its performance for bone infection has yet to be determined. The aim of this study was to evaluate a novel method to obtain and process infected bone tissue using PBCB and comparing it with the standard technique.Methods:Patients admitted at a single university hospital with foot osteomyelitis between 2008 and 2017 were recruited prospectively. The diagnosis was made by clinical, laboratory and imaging findings. A representative sample of infected bone tissue was obtained for each patient and simultaneously processed using the standard technique for solid tissue cultures (SCM) and a morselized bone sample that was seeded into a PBCB (BacT/ALERT® PF). Culture sensitivity and number of agents detected for each technique were compared using the McNemar and the Mann Whitney tests respectively.Results:Over the period studied, 107 patients fitted the inclusion criteria. Of these, 63 patients had a diabetic-related infection. The causative agent was identified in 60.7% using the SCM and in 97.2% using PBCB (p < 0.001). We detected a mean of 1.05 bacteria species using SCM and 1.67 using PBCB (p<0.01). PBCB retrieved 1 bacterial species in 50.5% of the samples and 2 or more bacterial species in 46.7%. The SCM detected 1 bacterial species in 29% of the samples and 2 or more bacterial species in 31.7%.Conclusion:In this cohort, culture technique using morselized bone tissue seeded in PBCB identified the causative agent in a significantly larger percentage than SCM. Additionally, this method identified a larger number of agents. These findings demonstrate that this novel, simple and reproducible technique for culturing bone tissue samples allows a better microbiological diagnosis, without additional intraoperative risks, compared with standard methods.

A novel intraoperative technique seeding morselized bone tissue into pediatric blood culture bottles improves microbiological diagnosis in patients with foot and ankle osteomyelitis

BackgroundOsteomyelitis, particularly cases involving the foot and ankle, is a challenging situation that frequently leads to amputations and major sequelae. Targeted antibiotics treating an identified pathogen are key to a successful outcome; however, traditional culture methods for bone tissue have poor sensitivity. This study prospectively compared a novel method for obtaining and processing infected bone tissue with the standard technique. Methods107 patients presenting with a diagnosis of osteomyelitis of the foot and ankle between 2008 and 2017 were prospectively included. Diagnosis was done according to clinical, laboratory and imaging findings. We obtained paired samples of bone tissue from all patients; they were processed through a usual culture method (UCM), but they were also morselized and seeded into pediatric blood culture bottles (PBCBs). We compared the culture yield and the number of agents detected using both the McNemar and the Mann–Whitney tests, respectively. ResultsWe studied 107 patients (63 with diabetic foot infection and 44 with nondiabetic osteomyelitis). The causative agent was identified in 60.7% of cases using the UCM and in 97.2% of cases using PBCBs (p < 0.001). We detected a mean of 1.05 ± 1.03 bacteria using the UCM and 1.67 ± 0.92 bacteria using PBCBs (p < 0.01). ConclusionCultures using morselized bone seeded in PBCBs identified the causative agent in a significantly larger percentage than the UCM. Additionally, this method identified a larger number of pathogen agents. A better agent identification method has advantages such as identifying more specific antibiotic treatment in these cases.

Diagnostic value of pediatric blood culture bottles for acute postoperative endophthalmitis

OBJECTIVE:To report our experience using conventional culture methods (CM) and pediatric blood culture bottles (PBCBs) for vitreous sample culture of acute postoperative endophthalmitis.METHODS:A retrospective study was conducted at the Department of Ophthalmology, Hospital das Clinicas, HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, BR, from January 2010 to December 2015, and it included 54 patients with clinically suspected acute postoperative endophthalmitis. Vitreous samples were obtained by vitreous tap or vitrectomy. Samples from January 2010 to December 2011 were cultivated in CM, whereas samples from January 2012 to December 2015 were inoculated in PBCBs. The measured outcome was the yield of positive cultures.RESULTS:Twenty cases were included in the CM group, and 34 cases were included in the PBCB group. The yield of positive cultures in PBCBs (64.7%) was significantly higher than that in conventional CM (35%, p=0.034). Staphylococcus epidermidis and Streptococcus viridans were the two most commonly found agents.CONCLUSION:PBCBs can be used successfully in clinically suspected endophthalmitis. The method showed a higher yield of positive cultures than the conventional method. This technique appears to have several advantages over the traditional method: it saves time, as only one medium needs to be inoculated; transportation to a laboratory is easier than in the traditional method, and there is no need to maintain a supply of fresh agar media. The use of PBCBs may be recommended as the primary method for microbiological diagnosis and is especially suitable for office settings and remote clinics.

Rapid Time to Positivity of Cerebrospinal Fluid Culture with Coagulase-Negative Staphylococcus Is More Likely to Reflect a True Infection Than Contamination

Cerebrospinal fluid (CSF) culture is the gold standard for diagnosing postoperative central nervous system infection. The time to positivity (TTP) of an automated continuous blood culture system may indicate the original concentration of the organism. Coagulase-negative Staphylococcus (CoNS), the common organism recovered in CSF, poses difficulty in differentiating infection from contamination. This study investigated the TTP of CSF culture with CoNS and its relationship to clinical parameters and prognosis. Adult neurosurgical patients with CoNS who recovered via the use of CSF culture in BacT/ALERT Pediatric FAN blood culture bottles and were admitted from September 2013 to July 2015 were enrolled. The demographics, clinical and microbiological data, and treatment were reviewed, and the TTP of each culture was retrieved. Thirty-nine adult patients with CoNS recovered from CSF culture were included. The TTP ranged from 7.68 to 57.36 hours. A univariate logistic regression analysis indicated patients with rapid TTP (<21.5 hours) compared with those with longer TTP were more likely to be female, show an effective response to antibiotic therapy within 7 days, have clean-contaminated surgical incisions, and show CSF leak. A multivariate logistic regression analysis indicated that being female, an effective antibiotic therapy within 7 days, and clean-contaminated surgical incisions were independent predictors of rapid TTP. Targeted antibiotic therapy was more likely to be beneficial to patients with a rapid TTP within 7days, which suggested that CoNS with a rapid TTP represents the pathogen of central nervous system infection rather than contamination in neurosurgical patients.

Erratum: Comparison of the BACTEC Peds Plus Pediatric Blood Culture Bottle to the BacT/Alert PF Pediatric Blood Culture Bottle for Culturing Blood from Pediatric Patients

Erratum: Comparison of the BACTEC Peds Plus Pediatric Blood Culture Bottle to the BacT/Alert PF Pediatric Blood Culture Bottle for Culturing Blood from Pediatric Patients

Clinical application of automated blood culture system in traumatic endophthalmitis

Objective To evaluate the clinical application of BacT/ALERT 3D automated blood culture system in traumatic endophthalmitis.Methods A total of 113 vitreous specimens of traumatic endophthalmitis were collected by BacT/ALERT PF pediatric blood culture bottle,detected by BacT/ALERT 3D automated blood culture system and analysed by Vitek-2 compact.We evaluated the positive rate,time to show positive,the types of microorganisms.Results In a total of 113 cultured vitreous specimens,81 cases were positive.Positive rate was 71.7％.Grampositive microorganisms accounted for 62.9％ of the positive culture results.Gramnegative microorganisms accounted for 34.6％ and fungi accounted for 2.5％.The shortest time to show positive was 4h.Conclusion The automated blood culture system has been widely used in blood and body fluid culture.The application of the automated blood culture for endophthalmitis can raise the positive detection rate,reduce the detection time to show positive and increase the types of microorganisms detected. Key words: Endophthalmitis; Microorganisms; Positive rate; Automated blood culture system

Comparison of the BACTEC Peds Plus Pediatric Blood Culture Bottle to the BacT/Alert PF Pediatric Blood Culture Bottle for Culturing Blood from Pediatric Patients

Blood samples were collected for culture from pediatric patients who were hospitalized during 2010 at a university hospital. BACTEC Peds Plus and BacT/Alert PF bottles were placed in the BACTEC FX and BacT/Alert 3D blood culture system, respectively, and tested for 5 days. Bottles flagged by instruments as positive were removed from the instruments and the TTDs were recorded.

Evaluation of blood culture bottles seeded with X–V factors for the detection of Neisseria meningitidis and Haemophilus influenzae

The purpose of this in vitro study was to determine the ability of seeded and not-seeded commercial pediatric blood culture bottles to support the growth of the most frequently responsible microorganisms for bacterial meningitides (Neisseria meningitidis, and Haemophilus influenzae). Tests have been carried out with an automated colorimetric pediatric blood culture system, BacTAlert, Organon Teknika. Bottles were inoculated with X-V factors and serial dilutions of the each bacterium in six times (10(1)-10(6) colony forming unit [CFU]/ml). The bottles, which were supplemented with X-V factors, proved to be effective and time to detection (TTD) was shorter than the un-seeded bottles (p0.05). Time difference between seeded and not-seeded bottles was getting greater at high dilutions of both bacteria. We consider that in presence of a few bacteria, the seeding of bottles with X-V factors is very critical obtaining N. meningitidis, and H. influenzae as the causative agents of meningitidis. The recovery rate of the microorganisms, which were isolated from cerebrospinal fluid by using the X-V factor-seeded blood culture bottles, is therefore higher than with the conventional culture methods.

Serotype Prevalence of Occult Pneumococcal Bacteremia

The licensure and use of a pneumococcal conjugate vaccine that is immunogenic in children who are younger than 2 years may affect the epidemiology of occult bacteremia. This study was conducted to determine the serotype prevalence of Streptococcus pneumoniae isolates from children with occult bacteremia and to document the proportion that would be covered by the recently licensed heptavalent pneumococcal conjugate vaccine. A cohort of 5901 children who were 2 to 24 months of age and had a temperature of >/=39.0 degrees C evaluated with a blood culture at an urban tertiary care children's hospital emergency department was studied to determine the prevalence of S pneumoniae serotypes. Patients were excluded if their immune system was suppressed, they had a diagnosis of a focal infection, they were evaluated by lumbar puncture, they were admitted to the hospital, or they died during initial evaluation. Blood cultures were inoculated into pediatric blood culture bottles and processed using an automated carbon dioxide monitoring system. All pneumococcal isolates were serotyped on the basis of capsular swelling with type-specific antisera (Quellung reaction). The study population consisted of 5901 patients. The overall rate of occult bacteremia was 1.9% (95% confidence interval [CI]: 1.5-2.3). S pneumoniae accounted for 92 of 111 isolates (82.9%; 95% CI: 74.6-89.4) in children with occult bacteremia. Eight pneumococcal serotypes were represented: 6A (2%), 9V (6%), 19F (6%), 18C (8%), 4 (9%), 6B (13%), 23F (15%), and 14 (42%). Serotypes 14, 6B, and 23F accounted for 69.3% (95% CI: 58.6-78.7) of typed isolates. In the cohort, 97.7% (95% CI: 92-99.7) of isolated serotypes are represented in the newly licensed heptavalent pneumococcal conjugate vaccine. The single isolated serotype that would not have been covered by the currently licensed heptavalent pneumococcal conjugate vaccine was 6A. S pneumoniae accounts for the vast majority of bacterial pathogens in children with occult bacteremia. As indicated by the results of this study, the heptavalent pneumococcal conjugate vaccine may prevent the majority of occult pneumococcal bacteremia episodes. The 2 cases of bacteremia with a serotype that would not have been included in the vaccine both were due to serotype 6A. It has been noted that there is potential nonvaccine serotype and subgroup cross-protection (6A from 6B) afforded to children who are immunized with the heptavalent vaccine. The high potential efficacy of the heptavalent pneumococcal conjugate vaccine for strains that cause occult bacteremia in our population may have a profound effect on the treatment of children with fever without a source. There has been an alarming and rapid emergence of antibiotic-resistant pneumococcal strains. Less pressure to use broad-spectrum antibiotics, which in turn causes further antibiotic resistance, should result. Laboratory testing and hospitalization also should be reduced. The prevalence rates determined by this study may be used as baseline data for comparison of serotype rates of occult pneumococcal bacteremia after widespread use of the heptavalent vaccine.

The Efficacy of Pediatric Blood Culture Sets in the Determination of Burn Bacteremia

A blood culture is an essential laboratory procedure necessary to confirm a septic episode. However, it is important to collect the blood sample at the appropriate time with an acceptable technique. The standard method is to collect at least 5 to 10 ml blood per culture bottle from patients with fevers. However, this volume of blood is an unrealistic amount to take from the frequently febrile pediatric patient. Alternatively, the pediatric blood culture bottle allows the collection of 1 ml blood per bottle to perform the same evaluation. We evaluated the two techniques of blood-culture collection over a 9-month period and compared the results between adult and pediatric blood culture bottles. Seventy-six patients, from November 1988 through February 1989, had blood cultures performed with the adult culture bottles, which produced a total of 1314 samples. A total of 113 patients, from March through July 1989, had blood cultures performed with the pediatric culture bottles, which produced a total of 758 samples. Percent recovery for the adult bottles versus the pediatric bottles was 13.95% versus 22.8% (p less than 0.0001). Since the amount of blood necessary to isolate an infectious agent is critical not only for laboratory identification but also for the volume of blood of pediatric patients, these data clearly establish the efficacy of pediatric blood culture bottles and the utilization of smaller amounts of blood. Not only did this approach significantly enhance organism recovery rate, but it may well be more cost-effective because fewer cultures need to be performed to isolate the infectious organism.

COMPARATIVE TRIAL OF ANTIBIOTIC REMOVAL DEVICE AND CONVENTIONAL BLOOD CULTURE IN PEDIATRIC PATIENTS

In patients with prior antimicrobial therapy recovery of microorganisms present in the blood is often delayed or prevented. Our clinical trial tested the usefulness of the Antibiotic Removal Device (ARD) in a pediatric population. Equal volumes of blood were inoculated in a sequentially randomized fashion into ARD and standard (STD) pediatric blood culture bottles. Each was independently processed and monitored by the early subculture technique. Clinical relevance of all isolates was independently determined by predefined criteria. Of a total of 966 cultures, 61 (6.3%) were positive.Although the ARD system may have been beneficial in the recovery of 3 Haemophilus influenzae strains susceptible to pretreatment antibiotics(*), there was no overall significant increase in bacterial isolation, and the recovery of S.pneumoniae from 6 patients (none on antibiotics) was actually significantly impaired.