Healthcare-associated blood stream infections: An evaluation of blood culture as indicator

Background: A nosocomial infection or healthcare-associated illness that develops in patients after they are admitted to the hospital but was not present or incubating at the time of admission is referred to as a hospital acquired infection. In patients with severe viral and fungal infections today, it is one of the most prevalent and life-threatening consequences. Blood culture is one of the most important diagnostic tools for the diagnosis of hospital acquired infections. It can also help in providing a clinical as well as an etiological diagnosis. Aims and Objectives: The aim of the study is early detection of blood stream infections along with its antibiotic susceptibility pattern. Materials and Methods: All samples were obtained and processed using conventional microbiological techniques, and an antibiotic sensitivity test was carried out in accordance with CLSI recommendations. Results: Total 160 samples were processed, out of which 54 (34%) samples were positive. Out of 54 positive blood sample, maximum samples were from NICU (28) 52%, followed by causality (10) 18%, PICU (4) 7%, HDU (2) 3%, intensive careunit (4) 7%, surgery (6) 11%, and overall males contributed to higher positivity rate. Total nine different organisms were isolated, out of which Gram negative bacilli were comprised 40 (74%), Gram positive cocci 8 (14%) and Candida were 6 (11%). Among Gram-negative bacilli of most common species were Klebsiella pneumonia (30%), Acinetobacter baumanii (18%), Pseudomonas aeruginosa (11%), Burkhoderia cepacia (11%), and Serratia fonticola (3%). The most prevalent isolated species of gram-positive cocci were Staphylococcus aureus (11%), Coagulase negative S. aureus (3%), and Enterococcus faecalis (3%). Conclusion: This study on blood culture gives insight to magnitude of hospital acquired infections in our set up. Again result of antibiotic susceptibility tests gives overview of drug resistance problem at our set up. This may help in antibiotic stewardship program.

Comparison of diagnostic accuracy of bactec culture, gene-xpert and histopathology in the diagnosis of genital tuberculosis in women with infertility

Background: Female genital tuberculosis (FGTB) is often a silent disease sparing no age group but majority of patients are in the reproductive age. In infertility patient’s incidence of FGTB varies from 3-16% in India but the actual incidence of genital tuberculosis may be under reported due to asymptomatic presentation and paucity of investigations.Methods: Prospective case control study was conducted from June 2018 to May 2019 in LLRM Medical College Meerut. A total 100 Endometrial samples were collected during diagnostic laparoscopy from all suspected case of genital TB, presented with either primary or secondary infertility and samples sent for histopathology, Gene-xpert and Bactec culture.Results: Out of 100 samples Bactec culture was positive in 2 samples, Gene-xpert positive in 3 samples. On histopathology out of 100 cases, non-specific endometritis was found in 1 case, tubercular-endometritis in 1 case, proliferative enometrium (anovulatory) in 40 cases and secretory endometrium found in 58 cases.Conclusions: Female genital TB poses a diagnostic dilemma because of its varied presentation and lack of sensitive and specific method of diagnosis. Culture though remains the gold standard of diagnosis of female genital TB, gene-xpert, histopathology, Bactec culture or laparoscopy can be used for starting treatment. Endometrial biopsy on histopathology shows not only Tubercular endometritis but also gives hormone response on endometrium, local factors of endometrium concerning non-specific and specific infections and anovulatory cycles.

Bronchoscopic Analysis in Sputum Smear Negative Pulmonary Tuberculosis Patients A Hospital based Study

Introduction: India has the highest burden of TB cases inthe world, majority of them are pulmonary tuberculosis.The method of choice for diagnosis of PTB is microscopicexamination of AFB by sputum smear. However, 30 to 50%of patients with pulmonary tuberculosis can have negativesputum report or may not produce sputum. Flexible fibreopticbronchoscopy can provide excellent material for diagnosis forpatients with suspected sputum smear negative pulmonarytuberculosis. Study aimed to evaluate the role of fiberoptic bronchoscopy in sputum smear negative pulmonorytuberculosis.Material and methods: Forty suspected cases of pulmonaryTB with clinical and radiological evidence of tb and sputumsmear negative on 2 occasions were selected for thisprospective nonrandomised observational study. Detailedexamination of the bronchial tree was done and specimensincluding bronchial aspirate and lavage was collected andsend for investigations. Post bronchoscopy sputum (PBS) wasalso collected and sent for smear microscopy.Results: In our study of 40 patients, tuberculosis wasconfirmed in 13 (32.50%) by smear examination of AFB inBroncho alveolar fluid and by post bronchoscopy sputumsmear examination in 3/40 (7.5%) cases. A definitive diagnosisof tuberculosis was possible in 23 (57.5%) of the 40 patientsby AFB culture by BACTEC MGIT960.Conclusion: Fibreoptic bronchoscopy with post bronchoscopysputum,BAL and BAL AFB culture is a useful tool fordiagnosis and can thereby prompt treatment of sputum smearnegative pulmonary tuberculosis patients.

Study of blood cultures by BACTEC method in pediatric patients of Chhattisgarh, India

Background: 356 children aged' between 2 to 4 years admitted at PICU were selected for study B.D BACTEC 9050 system was used for incubation bottle' were incubated until microbial growth was detected, BACTEC 9050 is an automated blood culture system which responds to concentration of' Co2 produced by metabolism microorganism or consumption of O2, needed for growth of microorganism.Methods: The antibiotic used were Amoxicin 250 mcg, penicillin 100 unit linezoid 50 Mcg, vancomycin 50 mcg, ampicillin 100 mcg, Azithromycin 100 Mcg, pipericillin/ Tozabactum, 100/50mcg, ceforazone/ salbactum 50/30 mcg, cefoxitin 50 mcg, cefepime 50 mcg, Amikacin 50 mcg, Imipenen 30 mcg, ceftazidime- clavulanic acid..Results: The observed organized were 90 (25.2%) CoNS, 72 (20.2%) Entrobacter, 70 (19.6%) Klebesiella' spp, 40(11.1%) Enterococcus, 22(6.1%) S, auresis, 22 (6.1%) E coli,' 20(5.6%) citrobacters, 20(5.6%) Acinitobacter. This blood culture study' by BACTEC 9050 in pediatric patients in few minutes.Conclusions: BACTEC-9050 method was helpful to treat especially in children because most of diseases in children are idiopathic and life threatening.

Evaluation of GeneXpert MTB/RIF and BACTEC-MGIT 960 for the detection of tuberculosis among pneumoconiosis-associated tuberculosis patients / 中华劳动卫生职业病杂志

Objective@#To evaluate the performence of GeneXpert MTB/RIF and BACTEC-MGIT 960 on detecting Mycobacterium tuberculosis and rifampicin resistance for pneumoconiosis-associated tuberculosis patients.@*Methods@#The recruited 133 suspected active pneumoconiosis-associated tuberculosis hospitalized cases, morning sputum samples were collected to do modified L-J culture, conventional proportion method drug susceptibility test, GeneXpert MTB/RIF and BACTEC-MGIT 960. Analyze the sensitivity and specificity of the 133 sputum from patients, the positive rates of patients with tuberculosis in GeneXpert MTB/RIF test, BACTEC-MGIT 960 and modified L-J culture were 37.59%, 34.59% and 30.08% respectively. There was no significant difference among the three tests respectively (P>0.05) . According to the modified L-J culture, the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting tuberculosis were 92.5% and 95.0% respectively, and specificity in rifampicin resistance were 86.0% and 91.4% respectively. There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960 (P>0.05) . According to conventional proportion method drug susceptibility test, the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting rifampicin resistance were 90.0% and 100%, and specificity were 92.6% and 96.4%. There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960 (P>0.05) .@*Conclusion@#The GeneXpert MTB/RIF has good performence of detecting tuberculosis and rifampicin resistance. It has good application value among pneumoconiosis-associated tuberculosis patients.

Rapid culture-based detection of living mycobacteria using microchannel electrical impedance spectroscopy (m-EIS)

BACKGROUND: Multiple techniques exist for detecting Mycobacteria, each having its own advantages and drawbacks. Among them, automated culture-based systems like the BACTEC-MGIT™ are popular because they are inexpensive, reliable and highly accurate. However, they have a relatively long "time-to-detection" (TTD). Hence, a method that retains the reliability and low-cost of the MGIT system, while reducing TTD would be highly desirable. METHODS: Living bacterial cells possess a membrane potential, on account of which they store charge when subjected to an AC-field. This charge storage (bulk capacitance) can be estimated using impedance measurements at multiple frequencies. An increase in the number of living cells during culture is reflected in an increase in bulk capacitance, and this forms the basis of our detection. M. bovis BCG and M. smegmatis suspensions with differing initial loads are cultured in MGIT media supplemented with OADC and Middlebrook 7H9 media respectively, electrical "scans" taken at regular intervals and the bulk capacitance estimated from the scans. Bulk capacitance estimates at later time-points are statistically compared to the suspension's baseline value. A statistically significant increase is assumed to indicate the presence of proliferating mycobacteria. RESULTS: Our TTDs were 60 and 36 h for M. bovis BCG and 20 and 9 h for M. smegmatis with initial loads of 1000 CFU/ml and 100,000 CFU/ml respectively. The corresponding TTDs for the commercial BACTEC MGIT 960 system were 131 and 84.6 h for M. bovis BCG and 41.7 and 12 h for M smegmatis, respectively. CONCLUSION: Our culture-based detection method using multi-frequency impedance measurements is capable of detecting mycobacteria faster than current commercial systems.

Effectiveness of Tuberculosis Smear Microscopy in Laboratory Diagnosis of Mycobacterium tuberculosis in Resource Constrained Settings.

Aim: To determine the correlation of accuracy of direct smear microscopy compared with BACTEC MGIT 960. Design: The study prospectively compare direct smear microscopy with BACTEC MGIT 960 using the reference standard, Lowenstein Jensen culture. Place and Duration: The study was conducted in Zankli Medical Centre, Abuja, between November 2004 and July 2005. Methodology: 340 suspected patients for Mycobacterium tuberculosis referred from direct observation therapy clinics located in six different government owned health facilities were referred to our facility. These patients; male (192) and female (148) were between the age of 10 and 64 years old. Three sputa samples were collected over two consecutive days and direct smear microscopy and culture were performed on these samples. Results: When compared with the reference standard, BACTEC MGIT 960 has a sensitivity and specificity of 100.0% and 56.4% respectively, and a negative predictive value of 100.0%; indicating the proportion of AFB negative participants were actually not infected with M. tuberculosis when tested with BACTEC MGIT 960. The sensitivity of direct microscopy was significantly lower than BACTEC MGIT 960 (84.9% versus 100%, p<0.001) and the specificity was significantly higher (96.6% versus 56.4%, p<0.001). Conclusions: For the purpose of effectiveness of tuberculosis program in developing countries, direct smear microscopy may still be relevant in the diagnosis of Mycobacterium tuberculosis.

Bacterial Isolates and their Antibiotic Sensitivity Pattern in Clinically Suspected Cases of Fever of Unknown Origin.

The present study was conducted on 100 suspected cases of fever of unknown origin to identify the prevalence of predominant bacterial microorganisms and their drug sensitivity pattern. The blood samples were subjected to conventional blood culture and BACTEC 9050 culture system. Out of 100 suspected cases, culture positivity was seen in 46% cases with 80.43% pathogenic bacterial isolates comprising of 54.05% gram positive and 45.94% gram negative isolates. Predominant gram positive isolates were coagulase negative Staphylococcus 35% followed by 30% Staphylococcus aureus with sensitivity to vancomycin (100%) and resistance to ampicillin, cloxacillin & cefalexin. Gram negative isolates were Salmonella typhi (29.41%) followed by E coli (17.64%) showing sensitivity to piperacillin/tazobactum and cefoperazone/sulbactum (90%) each and resistance to amoxicillin. BACTEC 9050 was observed to be sensitive(100%) as compared to conventional blood culture(67.56%) for cultural isolation of pathogenic organisms in clinical specimens.

Detection of Mycobacterium in fine-needle aspiration biopsy specimens from children with tuberculous lymphadenitis / 中华微生物学和免疫学杂志

Objective To improve the diagnosis of tuberculosis ( TB) by analyzing Mycobacterium infection in fine-needle aspiration biopsy specimens from children with tuberculous lymphadenitis .Methods Fine-needle aspiration biopsy was performed on 269 children with tuberculous lymphadenitis diagnosed by Shanghai Public Health Clinical Center from January 2011 to September 2013 .The needle aspiration biopsy specimens were processed for acid-fast bacillus (AFB) smear test, mycobacterial culture and Mycobacterium identification ( p-nitrobenzoic acid inhibition test ) .Results Cytological diagnosis of tuberculous lymphade-nitis was made for 269 patients.The positive results by AFB smear test were detected in 63.19% of 269 specimens (n=170) and 40.15%(n=108) specimens were positive in mycobacterial culture .The differ-ence between the two tests were significant (P<0.01).The positive rate of Mycobacterium detected by using BACTEC MGIT 960 automated system and L?wenstein-Jensen culture method were 38 .66% ( n=104 ) and 28.99%(n=78), respectively, showing the significant difference between two tests (P<0.05).AFB smear test in combination with mycobacterial culture could precisely diagnose 70.63% of tuberculous lym-phadenitis in children.Of the 108 clinical isolates, 105 strains (97.2%) were Mycobacterium tuberculosis complex and the rest were non-tuberculous Mycobacterium strains (2.8%).Conclusion The positive rate by AFB smear test was significantly increased in fine needle aspiration biopsy specimens after a series of treatments including sample digestion , centrifugation and precipitation , but the positive rate of mycobacterial culture was reduced .Diagnostic accuracy could be significantly improved by using BACTEC MGIT 960 sys-tem.Mycobacterium tuberculosis complex was the predominant pathogenic bacterium in children with tubercu-lous lymphadenitis .

Prevalence of Bacterial Contamination when using a Diversion Pouch during Blood Collection: A Single Center Study in Malaysia

Background: The implementation of diversion pouches is to minimise the risk of bacterial contamination as the initial blood flow is prevented from entering primary bag collections as it is diverted into a pouch. This study was carried out to determine the prevalence of bacterial contamination in the diversion pouches used  during blood collections in the Transfusion Department of Hospital Seberang Jaya, Penang, Malaysia. Methods: BD Bactec™ Fx instrument detection system was performed on 702 samples of 20 mL of  diverting blood in diversion pouch. The  inocullum  volume was 10 mL for both aerobic and anaerobic bottles cultures and incubated for 5 days in  the BD Bactec™ Fx instrument. Positive sample was flagged by BD Bactec™ Fx instrument and  subculture  to identify the species of organism. Results: The results  showed that of 702 samples, 12 (1.7%) were contaminated. The bacterial species identified were coagulase negative Staphylococcus, Staphylococcus aureus and Gram positive Bacilli. Conclusion: The results  strongly suggest that the usage of diversion pouch is of significant importance in reducing bacterial contamination during blood collection.

Diagnostic appraisal of simultaneous application of two nested PCRs targeting MPB64 gene and IS6110 region for rapid detection of M. tuberculosis genome in culture proven clinical specimens.

Background: Early diagnosis of tuberculosis is critical for its effective management and prevention. Several gene amplifi cation methods are used in the detection of tubercle bacilli from clinical specimens. MPB64 gene and IS6110 region have been identifi ed as potential gene targets for the specifi c detection of Mycobacterium tuberculosis from direct clinical specimens. Objective: The present study was conducted to evaluate the diagnostic utility of simultaneous application of two nested polymerase chain reaction (nPCRs) targeting MPB64 and IS6110 region for the detection of M. tuberculosis genome. Materials and Methods: A total of 100 and 354 clinical specimens from the control group and clinically suspected tuberculosis patients, respectively, were included in the study. nPCRs targeting MPB64 and IS6110 region were performed. Results and Conclusion: All of the 100 clinical specimens from the control group were negative for both nPCRs. Out of the 354 clinical specimens, 339 were positive for both culture and nPCRs, 10 and 5 were positive for culture, and nPCR targeting IS6110 and MPB64 regions, respectively. To conclude, nPCRs targeting MPB64 and IS6110 region are reliable and specifi c targets when applied simultaneously on clinical specimens to attain 100% sensitivity for the detection of M. tuberculosis genome.

Antibacterial Activity of Medicinal Aqueous Plant Extracts against Mycobacterium tuberculosis

Tuberculosis (TB) remains a serious health problem in many regions of the world, and the development of resistance to antibiotics by this microbe created the need for new drugs to replace those which have lost effectiveness. This study assesses the medicinal anti-Mycobacterium tuberculosis properties of natural products obtained from plants collected from Eastern Libya. In this study aqueous extracts of nine different plants were assayed for their Mycobacterium tuberculosis inhibitory activity using the BACTEC MGIT960 susceptibility test method. The aqueous extracts of Ceratonia siliqua L, Helichrysum stoechas (L.) Moench and Thymus algeriensis did not show any activity against M.tuberculosis in different concentrations. The aqueous extract of Marrubium vulgare L. from Syria showed high activity against M. tuberculosis. Marrubium alysson L., Marrubium vulgare L., Pistacia lentiscus L, Quercus coccifera L, Thymus capitatus (L.) Hoffm. & Link, showed varying degrees of activity against M. tuberculosis. The results of this study show that aqueous extracts from six different medicinal plants have different effects against M. tuberculosis in vitro.

Direct inoculation on Phoenix panels for identification and antimicrobial susceptibility from positive BACTEC cultures: First study from India.

Purpose: This was a prospective study planned in a super-specialty hospital in Delhi to reduce turnaround times of identification-susceptibility results of positive blood cultures. Materials and Methods: One hundred consecutive single morphology non-duplicate cultures were inoculated on Becton Dickinson Phoenix™ panels by growth recovered directly from liquid BACTEC™ media and after pure growth on solid media. Results: Complete concordance was observed in 72.4% of gram-negative and 45.8% of gram-positive isolates. For gram-negative isolates, categorical agreement (CA) was >83% and essential agreement (EA) was >96% among all antibiotics tested, very major errors (VME) were 0.13%, major errors (ME) 0.54%, and minor errors (MiE) were 3.01%. For gram-positive isolates, VME was 0.73%, 1.10% MiE and no ME. It was observed that average time from receipt of specimen to release of reports was 30:34 h and 32 h for gram-negative and gram-positive isolates if reports of "Direct" panels were to be released. Conclusions: By direct panel inoculation, a decrease of at least 18-20 h in turnaround time was observed compared with the standard method. This helps early change to effective antibiotic therapy and also reduces the expenditure incurred for a patient's hospital stay by average Rs 20,000 ($443) per day.

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 / 대한임상미생물학회지

BACKGROUND: We compared the BACTEC Peds Plus (Becton Dickinson, USA) and BacT/Alert PF (bioMerieux, France) pediatric blood culture bottles in the context of recovery and time to detection (TTD) of bacteria and fungi from pediatric patients. METHODS: 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. RESULTS: A total of 5,018 sets (1 set, 1 BACTEC Peds Plus and 1 BacT/Alert PF) were evaluated. Overall, the recovery proportions for BACTEC Peds Plus and BacT/Alert PF bottles were 57% (134/195) and 69% (112/195), respectively. There was a significant difference between the 0.38% contamination rate in BacT/Alert PF bottles and the 0.16% contamination rate in BACTEC Peds Plus bottles (P=0.035). The average TTD for all microorganisms was significantly decreased for the BACTEC Peds Plus bottles (P=0.021), but was increased for Candida parapsilosis compared to the results for the BacT/Alert PF bottles (P=0.028). CONCLUSION: We conclude that the rate of detection and contamination is higher when BacT/Alert PF bottles are used than when BACTEC Peds Plus bottles are used for pediatric blood culture. The BACTEC Peds Plus bottles detect nearly all enrolled microorganisms significantly faster than do the BacT/Alert PF bottles.

Evaluation of BACTEC MGIT 960 system for recovery of Mycobacterium tuberculosis complex in Pakistan

We evaluated the performance of MGIT 960 system in terms of recover rate, detection time of mycobacteria and contamination rate from various human clinical specimens and compared it with already in use BACTEC 460 TB system and conventional LJ medium. This is the first reported study on MGIT 960 and its comparison with BACTEC 460 system in Pakistan. A total of 260 different clinical specimens received for the culture of mycobacteria were dealt during the six months study period. All the specimens were digested and decontaminated according to the standard N-acetyl-Lcysteine NaOH method. All the processed specimens were inoculated on both the liquid systems and solid medium and incubated for six weeks and eight weeks consecutively. A total of 44 mycobacterial isolates (Mycobacterium tuberculosis, n=43; Mycobacteria other than tuberculosis, n=1) were recovered from 260 clinical specimens. The recovery rate of M. tuberculosis complex was 97.6% on BACTEC MGIT 960 system and 93.0% on BACTEC 460 system and 83.7% on LJ medium. The mean detection time of mycobacteria on BACTEC MGIT 960 system was 11.2 days in smear positive cases, 14.2 days in smear negative cases and 14.8 days in smear positive cases on BACTEC 460 system. Contamination rates were 9.6% and 5.6% and 3.4% for BACTEC MGIT 960, BACTEC 460 system and LJ medium respectively. The non-radiometric, fully automated BACTEC MGIT 960 system has better diagnostic ability as compared with radiometric, semi-automated BACTEC 460 system and LJ medium, so it can be used as a reliable alternative in over burden laboratories.

Comparison of BACTEC Plus Aerobic/F Media and BacT/Alert FA Media to Detect Bacteria in Blood Culture Bottles Containing Peak Therapeutic Levels of Antimicrobials / 대한임상미생물학회지

BACKGROUND: Blood culture bottles with an antimicrobial removal system have been developed for patients treated with antibiotics. This study compared the ability of BACTEC Plus Aerobic/F bottles (Becton Dickinson, USA, BACTEC Plus) and BacT/Alert FA bottles (bio-Merieux Vitek, France) to effectively remove antimicrobials. METHODS: BACTEC Plus and BacT/Alert FA bottles were spiked with 5 mL human blood, peak therapeutic concentrations of 9 antimicrobials and 7 type strains. Three rounds of duplicate testing were completed per antimicrobial/strain combination and growth control without antimicrobials. The time to detection (TTD) and recovery rates for bacteria were compared for both systems. RESULTS: Overall, the BACTEC Plus and BacT/Alert FA recovered 76% (128/168) and 34% (57/168) of strains from test bottles, respectively. BACTEC Plus detected all of gram-positive bacteria except S. pneumoniae with ampicillin and ceftriaxone, but BacT/Alert FA detected 0~50% of gram-positive bacteria except E. faecalis with vancomycin and methicillin-resistant S. aureus with oxacillin. In presence of cefepime, cefotaxime, cefoxitin and ceftriaxone, BACTEC Plus detected 33~100% of gram-negative bacteria, but BacT/ Alert FA did not detect gram-negative bacteria at all. In presence of ciprofloxacin, BacT/Alert FA detected 100% of E. coli and K. pneumoniae compared with 33% of those for BACTEC Plus. Overall, TTD of BACTEC Plus was shorter than that of BacT/Alert FA except in detecting gram-negative bacteria with ciprofloxacin (P<0.05). CONCLUSION: BACTEC Plus Aerobic/F media containing peak therapeutic levels of antimicrobials are more effective and faster detection of bacteria than BacT/Alert FA media.

Effect of Delayed Entry into 2 Different Blood Culture Systems(BacT/Alert 3D and BACTEC 9120) on Culture Positivity / 中华医院感染学杂志

OBJECTIVE To evaluate the effect of delayed entry(0-24 h) into BacT/Alert 3D and BACTEC 9120 and the effect of 2 incubation temperatures(22 ℃ vs 35 ℃) on culture positivity.METHODS We utilized the BacT/Alert system with FA bottles and the BACTEC 9120 system with Plus(Aerobic) bottles.Four clinical bacterial species,Staphylococcus aureus,Escherichia coli,Streptococus pneumoniae,Candida albicans,were used as the test strains.and 5 ml of blood were added to each bottle.Each species was inoculated into the bottles 3 times at an inoculum size of 10 CFU/ml,102 CFU/ml and 108 CFU/ml,respectively.The inoculated bottles were cultured using the respective instruments after they were allowed to stand at room temperature(22 ℃)and 35 ℃ for 0,8,16 and 24 h.Time-to-detection and culture positivity were evaluated.RESULTS The delay in transportation of blood culture bottles stored at room temperature(22 ℃) or 35 ℃ had no effect on the recovery rate for BACTEC 3D at less than 24 h preincubation time and for BacT/Alert 9120 at less than 16h preincubation time.The positivity rate decreased significantly for BacT/Alert 9120 for 24 h of delay.Culture positivity of BacT/Alert 3D was higher than BACTEC 9120 for 24 h of delay.CONCLUSIONS The delayed entry for BacT/Alert 3D should be within 24 h,but the delayed entry for BACTEC 9120 should be within 16 h.

Use of in-house PCR for identification of Mycobacterium tuberculosis in BACTEC broth cultures of respiratory specimens

We evaluated the ability of a PCR assay to identify Mycobacterium tuberculosis complex (MTBC) from positive BACTEC® 12B broth cultures. A total of 107 sputum samples were processed and inoculated into Ogawa slants and BACTEC® 12B vials. At a growth index (GI) > 30, 1.0 ml of the 12B broth was removed, stored, and assayed with PCR. Molecular results were compared to those obtained by phenotypic identification methods, including the BACTEC® NAP method. The average times required to perform PCR and NAP were compared. Of the 107 broth cultures evaluated, 90 were NAP positive, while 91 were PCR positive for MTBC. Of particular interest were three contaminated BACTEC® 12B broth cultures yielding microorganisms other than acid-fast bacilli growth with a MTBC that were successfully identified by PCR, resulting in a mean time of 14 days to identify MTBC before NAP identification. These results suggest that PCR could be used as an alternative to the NAP test for the rapid identification of MTBC in BACTEC® 12B cultures, particularly in those that contained both MTBC and nontuberculous mycobacteria.

Evaluation of Combination of BACTEC Mycobacteria Growth Indicator Tube 960 System and Ogawa Media for Mycobacterial Culture / 대한진단검사의학회지

BACKGROUND: The combined use of liquid media and solid media is recommended for mycobacterial culture. We evaluated diagnostic performance of combination of BACTEC Mycobacteria Growth Indicator Tube (MGIT; Becton Dickinson, USA) and 2% Ogawa media (Korean Institute of Tuberculosis, Korea) for recovery of mycobacteria. METHODS: In September 2007, 1,764 specimens from 1,059 patients were cultured with MGIT and Ogawa. Acid fast bacilli (AFB) smear was fluorochrome-stained. The isolates were identified into Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) with PCR using Seeplex TB Detection Kit (Seegene, Korea). Recovery rate, time to detection (TTD), contamination rate, mixed growth rate and species distribution were analyzed. RESULTS: Two hundred thirty-five specimens (13.3%) from 165 patients (15.6%) were positive for mycobacterial culture. Recovery rates of mycobacteria from the group using both media, MGIT only, and Ogawa only were 13.3%, 12.1%, and 7.8%, respectively. While MGIT recovered 98.9% of MTB and 79.7% of NTM, Ogawa recovered 65.9% of MTB and 54.1% of NTM. TTDs of total mycobacteria/MTB/NTM in MGIT and Ogawa were 10.6/11.4/9.7 days and 31/29/33 days, respectively. MGIT TTDs of total mycobacteria/MTB/NTM from AFB-positive specimens were significantly shorter than those of AFB-negative specimens; 8.2/9.5/4.4 days vs 11.6/12.7/10.7 days. Contamination and mixed growth rate of MGIT were 9.6% and 3.7%. Primary culture of Ogawa recovered 1 MTB and 1 NTM among the 170 MGIT-contaminated specimens and 38 mycobacteria among 66 specimens that showed mixed cultures of MGIT. CONCLUSIONS: MGIT warrants sensitive and rapid isolation of mycobacteria. However, the combination of MGIT and Ogawa is more desirable to recover mycobacteria in the case of contaminations or mixed cultures.

Comparision of the conventional diagnostic techniques,BACTEC and PCR.

Two hundred and thirty samples from suspected pulmonary and extra pulmonary cases of tuberculosis were processed for detection of Mycobacterium tuberculosis by ZN smear examination, LJ medium culture, BACTEC radiometric culture and Polymerase Chain Reaction tests. A significant difference was seen in the sensitivities of different tests,ie.73.9% for PCR tests,34.78% for ZN smear examination, 52.17% for LJ culture and 58.69% for BACTEC culture. However,there was no significant difference in specificity of different tests(P> 0.05). PCR test sensitivity in pulmonary and extrapulmonary clinical samples was 74.0% and 78.5% respectively and found to be significantly higher (P<0.05) when compared with those of other tests. The mean detection time for M.tuberculosis was 24.03 days by LJ medium culture, 12.89 days by BACTEC culture and less than one day by PCR test.