Evaluation of the BacT/Alert microbial detection system with FAN aerobic and FAN anaerobic bottles for culturing normally sterile body fluids other than blood

Blood culture bottles for culturing cerebrospinal fluid in cases of bacterial meningitis caused by Enterococcus faecalis: A case report

Pathogen identification is essential for the treatment of bacterial meningitis. However, cerebrospinal fluid (CSF) culture tests are often negative when antimicrobial agents are administered before CSF is collected. Therefore, it is necessary to improve the culturing process for such samples. Here, we report a case of bacterial meningitis where the causative bacteria were detected by inoculating that patient's CSF samples into blood culture bottles. A 52-year-old man developed a fever and headache after undergoing transnasal transsphenoidal surgery for a nonfunctioning pituitary neuroendocrine tumor. He was suspected of having a wound infection, for which he was treated with cefozopran and vancomycin. A CSF test was also performed, owing to persistent fever, and bacterial meningitis was suspected. Although conventional CSF culture tests were negative, CSF cultures using blood culture bottles detected Enterococcus faecalis. The antimicrobial agents were therefore changed to ampicillin and gentamicin, after which the patient's meningitis improved. The blood culture bottles used contained adsorbed polymer beads with antimicrobial neutralizing properties, which likely contributed to the isolation of the bacteria. In addition to conventional cultures, ones done in blood culture bottles may be useful for diagnosing bacterial meningitis via CSF samples-particularly in cases where antimicrobial agents have already been administered.

How to Handle CT-Guided Abscess Drainages in Microbiological Analyses? Sterile Vials vs. Blood Culture Bottles for Transport and Processing

The aim of this investigation was to compare microbiological analyses of 100 computed tomography-guided drainages from infectious foci (thoracic, abdominal, musculoskeletal), transported and analyzed by two widely established techniques, that are (i) sterile vials or (ii) inoculated blood culture bottles. The mean number of detected microorganisms from blood culture (aerobic/anaerobic) or conventional method (sterile vial, solid and broth media) per specimen were comparable with 1.29 and 1.41, respectively (p = 1.0). The conventional method showed a trend towards shorter time-to-result (median 28.62 h) in comparison to blood culture incubation (median 43.55 h) (p = 0.0722). Of note, detection of anaerobes (13% vs. 36%) and the number of detected microorganisms in polymicrobial infections (2.76 vs. 3.26) differed significantly with an advantage towards conventional techniques (p = 0.0015; p = 0.035), especially in abdominal aspirations. Despite substantially overlapping results from both techniques, the conventional approach includes some benefits which justify its role as standard approach.

Effective and Rapid Microbial Identification in Pediatric Osteoarticular Infections Using Blood Culture Bottles

BACKGROUND

The detection and identification of pathogenic microorganisms are essential for the treatment of osteoarticular infection. However, obtaining a sufficient amount of specimen from pediatric patients is often difficult. Herein, we aimed to demonstrate the effectiveness of the blood culture bottle (BCB) system in pediatric osteoarticular infections. We hypothesized that our BCB culture method is superior to the conventional swab and tissue culture methods in terms of required specimen size, incubation time, and microbial identification rate.

METHODS

We analyzed the prospectively collected data of pediatric patients who underwent surgical treatment for osteoarticular infections between August 2016 and October 2019. Four needles were dipped in the infected fluid or tissue during the surgical procedure as soon as the infected area was exposed and were used to inoculate 2 aerobic pediatric BCBs and 2 anaerobic general BCBs. We also collected 2 conventional swab samples and 2 tissue samples from the identical area. The microbial identification rate and the time required for identification were compared between BCB, swab, and tissue cultures.

RESULTS

Forty patients constituted the study group; 13 patients had osteomyelitis, 17 patients had septic arthritis, and 10 patients had both. Of these 40 patients, the microbial identification rate was higher with BCB cultures (27 [68%]) than with swab cultures (18 [45%]; p = 0.004) or tissue cultures (15 [38%]; p < 0.001). Nine samples (9 patients [23%]) were only positive in the BCB culture. Positive microbial growth was not detected with conventional culture methods when microorganisms did not grow on the BCB culture. Compared with swab culture (4.3 ± 1.1 days; p < 0.001) or tissue culture (4.4 ± 1.1 days; p < 0.001), the BCB culture reduced the time required for microbial identification (3.5 ± 0.9 days).

CONCLUSIONS

In pediatric osteoarticular infections, the BCB culture system improved the microbial identification rate, reduced the time to identification, and permitted a smaller-volume specimen, compared with traditional culture systems.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Synovial fluid culture: agar plates vs. blood culture bottles for microbiological identification

OBJECTIVES

Bacteriological diagnosis of septic arthritis (SA) is complicated. Agar plates are the main culture method and yields 40-60% of positive bacterial detection. Addition of bottled culture broth (Bactec®) as a method for detecting synovial microorganisms is common. The advantages of this method and the combination of both have not been thoroughly investigated. This study evaluates an added value of the Bactec culture broth as a single method or as combined with the agar-plate culture.

METHODS

All culture aspirates of SA-suspected patients were analyzed. All cases with a positive result by either method were reviewed for background data and clinical diagnosis.

RESULTS

Out of 5000 synovial fluid samples, a clinical diagnosis of SA was suspected in 1024 cases. Samples processed by both culture methods were extracted during the same event. Bactec® vials were positive for significant bacterial detection in 113/148 cases (76.4%) while agar-plate cultures were positive in only 96/154 (62.3%) representing higher sensitivity of 0.5 vs. 0.42 and a positive predictive value (PPV) of 0.76 vs. 0.62. Bacterial detection by both methods combined was positive in 137/221 (62%) and did not achieve a significant increment.

CONCLUSIONS

The Bactec® method has many advantages in bacteriological identification of synovial infection, including a broader identification spectrum, faster response time, and superior qualities of identification although being more expensive. This method has a better yield in detecting septic arthritis and might be considered a single method for synovial fluid culture in cases suspected for SA.Key Points• The Bactec method had improved detection rates.• Culturing by agar plates and Bactec revealed higher sensitivity and lower specificity.• The use of the blood culture bottles (Bactec system) alone will raise the detection rate of septic arthritis with lower false positive rates and at lower costs.

Performance of the BacT/Alert Virtuo Microbial Detection System for the culture of sterile body fluids: prospective multicentre study

OBJECTIVES

Continuous monitoring blood culture systems are commonly used for sterile body fluid cultures. In this multicentre study, we evaluated the performance of the new-generation BacT/Alert Virtuo system compared to the BacT/Alert 3D and conventional culture for the recovery of microorganisms from sterile body fluids.

METHODS

Peritoneal, cerebrospinal, pericardial, pleural and synovial fluids from adult patients submitted for culture were collected from three different centres. Specimens were inoculated into two bottles of the same bottle type (SA, SN, FA Plus or FN Plus) in equal volumes for simultaneous incubation in the Virtuo and 3D instruments. Each specimen was also Gram stained and seeded to solid media.

RESULTS

A total of 811 specimens were inoculated to 1257 bottle pairs. The Virtuo and 3D showed equivalent recovery of clinically significant microorganisms (127/155, 81.9%, vs. 126/155, 81.3%, respectively). Solid media cultures recovered fewer pathogens than either continuous monitoring system (95/155, 61.3%, p <0.001), including significantly fewer Enterobacteriaceae and enterococci. The Virtuo was significantly faster than the 3D in median time to detection of isolates from the same specimen (12.5 (range, 2.8-101.5) hours vs. 15.5 (range, 4.3-78.5) hours, p <0.001). Direct specimen Gram stain detected the eventual pathogen in 30 (26.1%) of 115 significant positive specimens.

CONCLUSIONS

The BacT/Alert Virtuo system was equivalent to the 3D system in organism recovery from sterile body fluid culture but showed faster detection of growth as a result of design enhancements.

Performance Survey and Comparison Between Rapid Sterility Testing Method and Pharmacopoeia Sterility Test

The sterility test described in pharmacopoeial compendia requires a 14-day incubation period to obtain a valid analytical result. Therefore, the use of alternative methods to evaluate the sterility of pharmaceuticals, such as the BacT/Alert® 3D system, is particularly interesting, because it allows a reduced incubation period and lower associated costs. Considering that the BacT/Alert® 3D system offers several culture media formulations developed for this microbial detection system, the present study was aimed to evaluate and compare the performance of BacT/Alert® 3D with the pharmacopoeial sterility test. There was no significant difference between the ability of the culture media to allow detection of microbial contamination. However, the rapid sterility testing method allowed a more rapid detection of the challenge microorganisms, which indicates that the system is a viable alternative for assessing the sterility of injectable products.

Comparison of BacT/Alert FAN and FAN Plus Bottles with Conventional Medium for Culturing Cerebrospinal Fluid

We compared the BacT/Alert system FAN and FAN Plus media to conventional media for culturing cerebrospinal fluid (CSF) with 2,545 samples. FAN/FAN Plus bottles showed better performance for isolating microorganisms in CSF than conventional media (positive rate, 7.2% [182/2,545] versus 3.1% [80/2,545]). The incremental recovery rate of Cryptococcus neoformans from FAN Plus bottles was higher than that from FAN bottles.

Higher recovery rate of microorganisms from cerebrospinal fluid samples by the BACTEC culture system in comparison with agar culture

The aim of this study was to assess the diagnostic value of the BACTEC FX blood culture (BC) system as compared to the agar culture (AC) of cerebrospinal fluid samples (CSF), evaluating the recovery rate and the time to detection of microorganisms in a 3.5-year period. From December 2011 to May 2015, 1326 CSF samples (694 patients) were submitted to both AC and BC. Among the 150 positive samples (96 patients), 165 microorganisms were detected: 81 by both the protocols, 77 by BC alone, and 7 by AC alone, demonstrating a higher detection rate of BC (95.8%) than AC (53.3%). Although BC presents some disadvantages, it is able to improve the yield of clinically significant microorganisms, and it could potentially reduce the reporting time as compared to AC. The results obtained highlighted the necessity of a combined approach for the successful detection of central nervous system microbial infections.

Evaluation of growth based rapid microbiological methods for sterility testing of vaccines and other biological products

Most biological products, including vaccines, administered by the parenteral route are required to be tested for sterility at the final container and also at various stages during manufacture. The sterility testing method described in the Code of Federal Regulations (21 CFR 610.12) and the United States Pharmacopoeia (USP, Chapter <71>) is based on the observation of turbidity in liquid culture media due to growth of potential contaminants. We evaluated rapid microbiological methods (RMM) based on detection of growth 1) by adenosine triphosphate (ATP) bioluminescence technology (Rapid Milliflex(®) Detection System [RMDS]), and 2) by CO(2) monitoring technologies (BacT/Alert and the BACTEC systems), as alternate sterility methods. Microorganisms representing Gram negative, Gram positive, aerobic, anaerobic, spore forming, slow growing bacteria, yeast, and fungi were prepared in aliquots of Fluid A or a biological matrix (including inactivated influenza vaccines) to contain approximately 0.1, 1, 10 and 100 colony forming units (CFU) in an inoculum of 10 ml. These preparations were inoculated to the specific media required for the various methods: 1) fluid thioglycollate medium (FTM) and tryptic soy broth (TSB) of the compendial sterility method (both membrane filtration and direct inoculation); 2) tryptic soy agar (TSA), Sabouraud dextrose agar (SDA) and Schaedler blood agar (SBA) of the RMDS; 3) iAST and iNST media of the BacT/Alert system and 4) Standard 10 Aerobic/F and Standard Anaerobic/F media of the BACTEC system. RMDS was significantly more sensitive in detecting various microorganisms at 0.1CFU than the compendial methods (p<0.05), whereas the compendial membrane filtration method was significantly more sensitive than the BACTEC and BacT/Alert methods (p<0.05). RMDS detected all microorganisms significantly faster than the compendial method (p<0.05). BacT/Alert and BACTEC methods detected most microorganisms significantly faster than the compendial method (p<0.05), but took almost the same time to detect the slow growing microorganism P. acnes, compared to the compendial method. RMDS using SBA detected all test microorganisms in the presence of a matrix containing preservative 0.01% thimerosal, whereas the BacT/Alert and BACTEC systems did not consistently detect all the test microorganisms in the presence of 0.01% thimerosal. RMDS was compatible with inactivated influenza vaccines and aluminum phosphate or aluminum hydroxide adjuvants at up to 8 mg/ml without any interference in bioluminescence. RMDS was shown to be acceptable as an alternate sterility method taking 5 days as compared to the 14 days required of the compendial method. Isolation of microorganisms from the RMDS was accomplished by re-incubation of membranes with fresh SBA medium and microbial identification was confirmed using the MicroSEQ Identification System. BacT/Alert and BACTEC systems may be applicable as alternate methods to the compendial direct inoculation sterility method for products that do not contain preservatives or anti-microbial agents.

The additional value of blood culture bottles in the diagnosis of endophthalmitis

PURPOSE

To assess the additional value of blood culture bottles (BCBs) in the diagnosis of endophthalmitis by comparing its culture yield with that of conventional media (CM).

DESIGN

Retrospective consecutive case series.

METHODS

We included patients who were treated between January 2001 and January 2010 for clinically suspected endophthalmitis of any etiology, and had vitreous specimens cultivated in both BCB and CM.

RESULTS

Specimens from 85 eyes from 85 patients were included. The culture yield of BCB was 69%, and that of CM was 72% (difference not significant). Adding the results of BCB improved the yield of CM significantly by 13%, resulting in a combined yield of 81%. The sensitivity of detection of Haemophilus influenzae in BCB seemed lower compared with CM, possibly due to the lack of growth factors in the BCB. There was no difference in yield between specimens obtained by tap or by vitrectomy.

CONCLUSION

In contrast with earlier reports, we did not find BCB superior to CM. The combined use of BCB and CM increased the pathogen detection rate significantly and should therefore be considered as the microbiological method of choice in the work-up of endophthalmitis.

Comparison of the BACTEC blood culture system versus conventional methods for culture of normally sterile body fluids

This study compared the BACTEC blood culture system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md) with conventional culture methods for recovery and time to detection of significant isolates from normally sterile body fluids. A total of 412 specimens were included in the study. Half of the specimens were inoculated directly into the automated blood culture system. The remaining specimens were centrifuged at 3000 rpm for 10 min and were inoculated onto conventional media. Clinically significant microorganisms were isolated from 41 specimens (10%) by both culture systems; however, for 62 specimens (14.9%), growth was detected only with the BACTEC system. No isolates were detected with only conventional culture methods. A significant difference was noted between the blood culture system and routine culture methods for recovery of pathogenic microorganisms that were from sterile body fluids. The most frequently isolated microorganisms recovered only with the blood culture system were gram-positive cocci; gram-negative bacilli were the most frequently isolated microorganisms that were recovered with both culture methods. Streptococcus pneumoniae, Streptococcus viridans, Aeromonas hydrophila, and Brucella were recovered only with the blood culture system. Furthermore, the mean time to detection of significant pathogens was significantly less with the blood culture system than with conventional media. The BACTEC blood culture system was found to improve the yield of clinically significant isolates from normally sterile body fluids with reduced time to detection; it may be advantageous for isolation of fastidious microorganisms, such as Brucella and S pneumoniae, especially from cerebrospinal and synovial fluid specimens.

Evaluation of the Bactec microbial detection system for culturing miscellaneous sterile body fluids

This study sought to evaluate the efficacy of the Bactec blood culture system for culturing sterile body fluids, in comparison with traditional culture methods. A total of 906 specimens were cultured using both conventional media and the Bactec detection system. Differences in numbers of isolates determined by each system were compared. Clinically significant microorganisms were isolated from 15.3% (139) of 906 specimens by both the Bactec system and conventional culture, whereas for 8.8% (80) of the specimens a positive culture was obtained by Bactec only. Of the 80 specimens in which growth was detected only in the Bactec blood culture system, 11.0% were comprised of cerebrospinal fluid, 9.9% peritoneal fluid, 4.9% pleural fluid, 4.5% synovial fluid and 9.1% bone marrow materials. Strains of Brucella melitensis, Neisseria meningitidis, Pseudomonas fluorescens and Rothia dentocariosa were cultured only by the Bactec system. In conclusion, the Bactec blood culture system might be advantageous for isolation of fastidious microorganisms such as Brucella, especially from cerebrospinal and peritoneal fluid specimens.

Comparison of automated culture systems with a CFR/USP-compliant method for sterility testing of cell-therapy products

BACKGROUND

Although widely used, commercially available automated culture methods are not US Food and Drug Administration-approved for sterility testing of cell-therapy products. For cell-therapy products regulated under Section 351 of the Public Health Service Act, sterility testing must be performed by the methods described in 21 CFR 610.12 and USP <71> (CFR/USP method), or by methods demonstrated to be equivalent.

METHODS

Two automated methods, BacT/Alert (BTA; bioMerieux) and Bactec (Becton Dickinson), were compared with the CFR/USP method. Representative mononuclear cell (MNC) products were formulated using six different product media. MNC product aliquots containing 10-50 x 10(6) cells in a 0.5 mL volume were seeded with organisms, and cultured for 14 days in aerobic and anaerobic bottles of each system. Ten different organisms at target concentrations of 10 and 50 colony-forming units (CFU) per bottle were tested.

RESULTS

Positives were detected in a mean (range) of 72% (7-100%) of cultures for CFR/USP, 82% (0-100%) for BTA, and 93% (57-100%) for Bactec. For nine of the 10 organisms tested, overall detection rates for BTA and Bactec were equivalent to or higher than CFR/USP. Of the six product media tested, detection of organisms was impaired only by the medium containing multiple antibiotics: this occurred in all three systems. Both BTA and Bactec had shorter times to detection than the CFR/USP method, with overall means (ranges) of 87 (24-264) h for CFR/USP, 24 (12-54) h for BTA, and 33 (12-80) h for Bactec. Detection occurred consistently within 7 days for both BTA and Bactec, but not for CFR/USP.

DISCUSSION

Both BTA and Bactec are superior to the CFR/USP method for overall detection and time to detection of organisms in MNC products suspended in commonly used media. These data support general use of either BTA or Bactec for sterility testing of a variety of cell-therapy products, and suggest that a 7-day culture period is sufficient to detect clinically relevant organisms. These results confirm the need for bacteriostasis and fungistasis testing of antibiotic-containing products, even when antibiotic-binding substances are used.