Detection Of Microbial Growth Research Articles

The effect of taurolidine on the time-to-positivity of blood cultures

Taurolidine containing lock solutions (TL) are a promising method for the prevention of central line associated bloodstream infections. Per accident, the TL may not always be aspirated from the central venous catheter (CVC) before blood cultures are obtained. The TL could, unintentionally, end up in a blood culture vial, possibly altering the results. The aim of this study was to investigate the effect of the TLs on the detection of microbial growth in blood culture vials. Different lock solutions (taurolidine-citrate-heparin (TCHL), taurolidine, heparin, citrate or NaCl) were added to BD BACTECTM blood culture vials (Plus Aerobic/F, Lytic/10 Anaerobic/F or Peds Plus/F) before spiking with Staphylococcus aureus (ATCC 29213 or a clinical strain) or Escherichia coli (ATCC 25922 or a clinical strain) in the presence and absence of blood. Subsequently, blood culture vials were incubated in the BD BACTEC FX instrument with Time-to-positivity (TTP) as primary outcome. In addition, the effect of the TCHL on a variety of other micro-organisms was tested. In the presence of taurolidine, the TTP was considerably delayed or vials even remained negative as compared to vials containing heparin, citrate or NaCl. This effect was dose-dependent. The delayed TTP was much less pronounced in the presence of blood, but still notable. This study stresses the clinical importance of discarding TLs from the CVC before obtaining a blood culture.

Bacterial Profile and their Antimicrobial Susceptibility Pattern in Pediatric Septicemia patients from Tertiary Care Hospital.

Background:
 Blood stream infection is a life-threatening infection, leading to increased morbidity and mortality in pediatric population. Antimicrobial drug resistance is a major therapeutic challenge and may result in treatment failure. Thus, this study aimed to assess the bacterial profile causing septicemia and their antimicrobial resistance pattern among pediatric population.
 Methods: 
 This reterospective study was conducted in pathology department of Hameed Latif Hospital, Lahore, over a period of two years, from 1st January 2021 to 31 December 2022. Blood samples were aseptically collected and were transferred into Bact/Alert blood culture bottle. After the detection of microbial growth by Bact/Alert 3D system, bacterial isolates were identified by standard microbiological procedures. Antimicrobial sensitivity pattern was determined by Modified Kirby-Bauer disc diffusion method on Mueller Hinton agar. Data was entered and analyzed by using Microsoft Excel 2010.
 Results:
 In our study, out of 1306 blood culture samples, 217(16.6%) were positive for bacterial growth. Among positive cases, Gram negative organisms were predominant isolates 181(83.4%), while Gram positive organisms were isolated in 36(16.6%) samples. Most common bacterial isolates were S. typhi (24%), A.baumanii (19%), P.aeruginosa (9%), while S.aureus and MRSA were 8% each. Highly resistant class of drugs for Gram-positive bacteria were found to be Aminopenicillin (69.1%) and Macrolides (68.6%), while Gram-negative organisms showed maximum resistance against Tetracycline (72.9%), Fluoroquinolones (62.1%) and Cephalosporins (61%).
 Conclusion:
 Bacterial isolates clinically suspected cases of septicemia were high. Majority of bacterial isolates showed maximum drug resistance against different classes of antibiotics. To prevent antibiotic resistance, strict regulation of antibiotic utilization and infection control programs should be implemented.

Trend of Antimicrobial Resistance Among Salmonella Typhi Isolated from Pediatric Population Presenting at a Tertiary Care Hospital in Lahore

<p><strong>Background and Objective:</strong> Typhoid fever caused by Salmonella typhi (S. typhi) is an important cause of morbidity and mortality worldwide. The emergence of resistance against the first and second line of drugs has limited the range of drug choices for its treatment. Therefore, the present study was designed to assess the status of drug resistance in S. typhi isolated from the blood samples of pediatric patients reporting at a leading tertiary care hospital in Lahore.</p>
 <p><strong>Methods:</strong> This descriptive study was conducted at the Pathology Department of Allama Iqbal Medical College, Lahore, Pakistan, over a period of 2 years. A total of 1,306 blood samples were aseptically collected from the pediatric population of Jinnah Hospital, Lahore, Pakistan, after obtaining informed assent from the parents/guardians. The samples were transferred into a Bact/Alert blood culture bottle. After the detection of microbial growth by the Bact/Alert 3-D system, bacterial isolates were identified by standard microbiological procedures. VITEK 2 compact automated identification and antimicrobial susceptibility testing instrument (bioMerieux) was used for the antimicrobial sensitivity testing. Data were entered and analyzed by using Statistical Package for the Social Sciences version 21.0.</p>
 <p><strong>Results:</strong> A total of 235 out of 1,306 (17.9%) blood culture samples yielded bacterial growth, among which 62.5% (n = 147) were S. typhi. Among 147 S. typhi isolates, 70.6% were multidrug resistant, while 63% were extensively drug resistant (XDR). Maximum resistance against first-line drugs observed was for ampicillin (79.4) and co-trimoxazole (67.2).</p>
 <p><strong>Conclusion: </strong>The emergence and spread of XDR S. typhi with a high level of resistance are quite alarming, leaving limited treatment options for the pediatric population. Moreover, increasing resistance to antibiotics demonstrates the quick waning of the efficacy of available first and second-line drugs in the treatment of typhoid fever.</p>

A two-centre validation study of sterility test of corneal storage media with elimination of interfering antimicrobials in compliance with the European Pharmacopoeia.

The purpose of this study was to validate the sterility test of corneal culture and deswelling/transport media using a device for removal of antimicrobials before incubation in BACTEC™ automated system in two Italian Eye Banks. Corneal culture medium, TISSUE-C, and deswelling/transport medium, CARRY-C, were inoculated with 10-100cfu of six European Pharmacopoeia (EP) reference strains and either treated with medical device RESEP for removal of antimicrobials (RESEP+ group) or left untreated (RESEP- group) before injection into the BACTEC Plus bottles. The same steps were repeated in the absence of inocula with tryptone soy broth samples as negative controls, and the inocula were also directly injected in the BACTEC™ bottles as growth controls. All the samples were incubated in BACTEC™ automated system for7days, and the time to detection of microbial growth was recorded automatically. At both the Eye Banks, in the RESEP+ groups, microbial growth was detected in 100% of samples. In the RESEP- group, the method sensitivity ranged from 66.7 ± 21.1 to 88.9 ± 6.4% for TISSUE-C samples while for CARRY-C samples the method sensitivity ranged from 94.5 ± 5.1 to 100%. The method specificity corresponded to 100% for all the groups at both Eye Banks. This two-centre validation study showed that the use of RESEP increased the sensitivity of sterility test using BACTEC™ automated system up to 100% and, consequently, allowed validation of the method for sterility testing of corneal storage and deswelling/transport media according to the EP requirements. The test could not be validated without the use of RESEP.

FDA 2014 survey of eye area cosmetics for microbiological safety

In the United States, cosmetic products are regulated postmarket; therefore, surveillance programmes are one of FDA's most important tools for monitoring microbiological safety of cosmetics. 'Traditional' preservatives, such as parabens and formaldehyde releasers, are perceived unfavourably by some consumers, resulting in cosmetic manufacturers increasingly using 'nontraditional' preservatives. FDA conducted an analytical survey of eye area cosmetics that claimed to be free of traditional preservatives and determined microbiological loads in tested products. This study explores the association of microbial loads with the physical and chemical characteristics of the cosmetic products, and points to the limits of preservative activity in cosmetics.

Method for sterility testing of corneal storage and transport media after removal of interfering antimicrobials: prospective validation study in compliance with the European Pharmacopoeia

ObjectiveThis study aimed at validating the method for sterility testing of the corneal culture medium, TISSUE-C, and the transport/deswelling medium, CARRY-C, according to the method suitability test, as defined by...

Real-time optical monitoring of microbial growth using optimal combination of light-emitting diodes

We developed a real-time optical monitoring system consisting of a monochrome complementary metal-oxide semiconductor (CMOS) camera and two light-emitting diodes (LEDs) with a constant temperature incubator for the rapid detection of microbial growth on solid media. As a target organism, we used Alicyclobacillus acidocaldarius, which is an acid- ophilic thermophilic endospore-forming bacterium able to survive in pas- teurization processes and grow in acidic drink products such as apple juice. This bacterium was cultured on agar medium with a redox dye applied to improve detection sensitivity. On the basis of spectroscopic properties of the colony, medium, and LEDs, an optimal combination of two LED illuminations was selected to maximize the contrast between the colony and medium areas. We measured A. acidocaldarius and Escherichia coli at two different dilution levels using these two LEDs. From the results of time-course changes in the number of detected pixels in the detection images, a similar growth rate was estimated amongst the same species of microbes, regardless of the dilution level. This system has the ability to detect a colony of approximately 26 μm in diameter in a detection image, and it can be interpreted that the size corresponds to less than 20 μm diameter in visual inspection. © 2012 Society of Photo-Optical

Volatile organic compound analysis by ion molecule reaction mass spectrometry for Gram-positive bacteria differentiation

Approximately 50 % of all clinically proven infections in critically ill patients are caused by Gram-positive bacteria. The timely and appropriate treatment of these infections is vital in order to avoid negative outcomes. Hence, fast and reliable methods are needed for the early detection and identification of microorganisms. Recently, direct mass spectrometry-based analysis of volatile organic compounds emitted by microorganisms has been employed to study Gram-negative bacteria. Here, we report a feasibility study of ion molecule reaction mass spectrometry (IMR-MS) for in vitro growth detection and species differentiation of selected Gram-positive bacteria that are frequently isolated in blood culture samples, namely, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, and Staphylococcus epidermidis. Ion molecule reaction mass spectrometry was used to analyze the headspace above cultures containing Gram-positive bacteria incubated at 37 °C starting with 10(2) colony-forming units (CFU)/ml. Measurements to determine the presence of volatile organic compounds were performed 4, 8, and 24 h after incubation, respectively. The detection of microbial growth was accomplished already after 8 h in cultures containing E. faecalis. After 24 h of incubation, characteristic mass spectra were obtained for all species. Processing these mass spectra by hierarchic clustering and principal component analysis (PCA) enabled us to differentiate between bacterial species. IMR-MS in conjunction with a cumulative end-point model provides the means for rapid growth detection and differentiation of Gram-positive bacteria on the species level, typically within an analysis time of less than 3 min per sample.

Validation of the BacT/ALERT(R) 3D System for Rapid Sterility Testing of Biopharmaceutical Samples

The BacT/ALERT® 3D system was validated to determine the sterility of different types of biopharmaceutical samples such as water for injection, unprocessed bulk, and finished bulk. The installation, operation, and performance qualification were completed and verified under good manufacturing practices. During the installation and operation validation stages, the functionality and security of the system and software were completed and verified. For the performance qualification, 11 microorganisms were evaluated, six compendial (Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Aspergillus niger, Clostridium sporogenes), one representing the number one microbial species in sterile product recalls (Burkholderia cepacia), and four environmental isolates (Kocuria rhizophila, Staphylococcus haemolyticus, Methylobacterium radiotolerans, and Penicillium spp.). Nine of the microorganisms were spiked into three different types of biopharmaceutical samples by three different analysts on different days to ascertain the equivalence, ruggedness, sensitivity, time of detection, and repeatability. In all samples, the BacT/ALERT® exhibited equivalent or better detection than the standard test. With the exception of M. radiotolerans, all 11 microorganisms were detected within 2.5 days using the BacT/ALERT® system and the standard test. The detection times for M. radiotolerans in the three sample types averaged 5.77 days. The minimum detectable level of cells for all the microorganisms tested was found to be within 1 to 2 CFU. The system optimized sterility testing by the simultaneous on-line, non-destructive incubation and detection of microbial growth.

Use of polarography as a quality-control method for determining diacetyl in citrus and vegetable juices, yoghurt and butter

The determination of diacetyl permits the detection of microbial growth in the processing of citrus fruit before the appearance of other organoleptic, chemical or microbiological changes. It also makes it possible to detect a break in the cold chain during distribution and sale. The study proposed a polarographic method for the determination of diacetyl that allowed routine analysis with the aim of detecting possible contamination in the citrus juice manufacturing chain (orange and orange-carrot). The analytical performance of the method in terms of a linearity from 0 to 960 μg ml-1, a recovery of 97 to 98%, a precision of 3.2 to 4.8%, and a sensitivity of 0.2 ng ml-1 for juices indicated the robustness of the method. The same method was also applied to butter and yoghurt with detection limits of and 0.4 ng g-1.

5162229 Device and method for enhanced recovery and detection of microbial growth in the presence of antimicrobial substances: Thurman C Thorpe, James L DiGuiseppi, Richard C Driscoll, James Turner, Michael J Calandra assigned to Akzo N V

5162229 Device and method for enhanced recovery and detection of microbial growth in the presence of antimicrobial substances: Thurman C Thorpe, James L DiGuiseppi, Richard C Driscoll, James Turner, Michael J Calandra assigned to Akzo N V

Clinical comparison of the recoveries of bloodstream pathogens in Septi-Chek brain heart infusion broth with saponin, Septi-Chek tryptic soy broth, and the isolator lysis-centrifugation system

The recoveries of microorganisms in the Septi-Chek biphasic tryptic soy broth (TSB) and Isolator blood culturing systems were compared with the recovery in Septi-Chek biphasic brain heart infusion broth supplemented with the lytic agent saponin (L-BHIB; Roche Diagnostics, Division of Hoffmann-La Roche Inc.). A total of 5,096 TSB-L-BHIB blood culture sets and 1,778 Isolator-L-BHIB sets were evaluated. There were 435 pathogenic organisms recovered in 413 (8.1%) of the TSB-L-BHIB cultures, with 348 organisms in the TSB bottles and 370 in the L-BHIB bottles (P less than 0.05). Significantly more yeast isolates were recovered in the L-BHIB system (P less than 0.01). Terminal subculture of the L-BHIB system was required to detect 13 clinically significant organisms. Significantly more organisms were recovered in the L-BHIB bottles than with the Isolator system (P less than 0.001), including Torulopsis glabrata, coagulase-negative staphylococci, and Pseudomonas species. The time required for detection of all major groups of organisms was the same in both comparisons. However, detection of microbial growth in the L-BHIB bottles required macroscopic inspection of the attached agar slide unit and the use of terminal subcultures after 7 days of incubation. The primary advantage of the biphasic L-BHIB system when compared with either the biphasic TSB system or the Isolator system was improved recovery of fungi.

Bioluminescence for USP sterility testing of pharmaceutical suspension products

Bioluminescence measurement significantly improved the accuracy, sensitivity, precision, and reliability of the current visual endpoint determination for the USP sterility test and eliminated the day 7 transfer/dilution step required for testing suspension products. Thirteen strains of bacteria and fungi (representing potential contaminants in sterile products), three pharmaceutical suspension products, and four media were used in the experiment. No interference from suspension products was encountered in the detection of microbial growth by the bioluminescence measurement. The poor fungal growth encountered was attributed to insufficient diffusion of oxygen into the medium and was circumvented by use of a large tube size (38 by 200 mm) or by vortexing the medium once during the 2-week incubation period. Bioluminescence measurement would facilitate automated handling of the sterility test endpoint readout operation. The optimum parameters of bioluminescence measurement for application in sterility testing were determined.

Rapid detection of microbial growth in vegetable salads at chill and abuse temperatures

Bacteria, yeasts and moulds were identified as comprising the normal flora of chill stored, non-acidified vegetable salads. The isolates were chiefly Gram negative rods or Gram positive cocci and were mainly psychotrophs with some mesophiles. Pathogenic types were not found amongst the salads screened. In salad packs held at 7°C lactic acid bacteria formed a low proportion of the total population, whereas at 30°C lactic acid bacteria formed the dominant population. These differences between the population types led to the development of tests indicating shelf life or temperature abuse. A rapid test for detecting lactic acid and a technique based on the Gram stain are described as methods providing indication of temperature abuse well before visual spoilage occurred. The Limulus lysate test was shown to be a simple and rapid method for assessing the microbial quality of salads stored at chill and thus would provide a useful indicator of shelf life.