Conventional Broth Culture Research Articles

Candidemia in patients with prolonged fever in Kashan, Iran.

Background and Purpose: Candida species are considered a common cause of fungal blood stream infections, which are associated with considerable mortality and morbidity rates, especially in the admitted and immunocompromised patients. Despite the increase in new and available antifungal agents, the emergence of resistant strains is growing. Regarding this, the aim of the present study was to assess the fungal epide­miology of candidemia and the antifungal susceptibility patterns against five current antifungal agents among the patients with prolonged fever, who were admitted to Beheshti Educational Hospital, Kashan, Iran.Materials and Methods:This cross-sectional study was conducted on 253 hospitalized patients with prolonged fever despite receiving broad-spectrum antibiotic therapy. Blood samples were collected aseptically, and then cultured using an automated blood culture system and conventional broth culture bottle. Candida isolates were identified at species level using morphological and physiological properties and produced color on the CHROMagar Candida. Furthermore, the antifungal susceptibility testing was performed using (CLSI M27-A3 and CLSI M27-S4) broth microdilution methods.Results:The most positive cultures were detected by the automated blood culture system. C. albicans (%50) was the most prevalent species, followed by C. glabrata (%40), and C. parapsilosis, (%10) respectively .The mortality rate was high (%60) and most patients with candidemia were admitted to the Intensive Care Unit and Neonatal Intensive Care Unit. All isolates were susceptible to amphotericin B, while the highest resistance belonged to caspofungin.Conclusion:In this study, high resistance was reported, especially for caspofungin, which can be regarded as the emergence of caspofungin-resistant strains. Regarding this, the establishment of a surveillance and prevention program for the reduction of the emergence of resistant species is necessary.

A comparison of lysis centrifugation, pour plate, and conventional blood culture methods in the diagnosis of septicaemic melioidosis.

AIMS: To determine whether quantitative blood culture methods could improve the diagnosis of septicaemic melioidosis. METHODS: A comparison of conventional broth based blood cultures, a pour plate method, and a...

Quantitation of bacteria in blood of typhoid fever patients and relationship between counts and clinical features, transmissibility, and antibiotic resistance.

Salmonella typhi was isolated from 369 and Salmonella paratyphi A was isolated from 6 of 515 Vietnamese patients with suspected enteric fever. Compared with conventional broth culture of blood, direct plating of the buffy coat had a diagnostic sensitivity of 99.5% (95% confidence interval [CI], 97.1 to 100%). Blood bacterial counts were estimated by the pour plate method. The median S. typhi count in blood was 1 CFU/ml (range, <0.3 to 387 CFU/ml), of which a mean of 63% (95% CI, 58 to 67%) were intracellular. The mean number of bacteria per infected leukocyte was 1.3 (interquartile range [IQR], 0.7 to 2.4) CFU/cell (n = 81). Children (< 15 years old; n = 115) had higher median blood bacterial counts than adults (n = 262): 1.5 (range, <0.3 to 387) versus 0.6 (range, <0.3 to 17.7) CFU/ml (P = 0.008), and patients who excreted S. typhi in feces had higher bacteremias than those who did not: a median of 3 (range, <0.3 to 32) versus 1 (range, <0.3 to 68) CFU/ml (P = 0.02). Blood bacterial counts declined with increasing duration of illness (P = 0.002) and were higher in infections caused by multidrug-resistant S. typhi (1.3 [range, <0.3 to 387] CFU/ml; n = 313) than in infections caused by antibiotic-sensitive S. typhi (0.5 [range, <0.3 to 32] CFU/ml; n = 62) (P = 0.006). In a multivariate analysis this proved to be an independent association, suggesting a relationship between antibiotic resistance and virulence in S. typhi.

Blood cultures from Bangladeshi children with septicaemia: an evaluation of conventional, lysis-direct plating and lysis-centrifugation methods

The use of a laboratory-made lysis-direct plating and lysis-centrifugation (LDP/LC) device for blood cultivation has been compared with the conventional broth culture method in respect of speed and sensitivity in detecting organism(s) and cost effectiveness. 400 blood cultures yielded 95 clinically significant isolates. Both methods recovered 73 organisms (76.8%); 20 (21%) were detected by LDP/LC methods only, and 2 (2.1%) were isolated by the conventional method only. All the 93 isolates (97.8%) recovered by LDP/LC were isolated within 48 h, whereas the broth culture method took 7 d to isolate a total of 75 organisms (78.9%). The LDP/LC method, with our laboratory-made device, costs one-fourth of the cost of the conventional broth culture system.

Evaluation of lysis filtration as an adjunct to conventional blood culture.

A lysis filtration system was used in conjunction with conventional broth culture for 1112 blood cultures. The system, which entailed collection of 5 ml of blood into bottles containing 50 ml isotonic phosphate buffer, Tween 20, and Rhozyme with subsequent filtration using a 0.45 micron Millipore field monitor, was simple and economical to use. Positive results were obtained earlier than those obtained with conventional broth cultures, and almost twice as many fungi and yeasts were isolated. Some fastidious organisms such as Haemophilus influenzae and Streptococcus pneumoniae however, were not recovered from the lysis system, and contaminants in lysis cultures were three times as common as in conventional culture. The number of positive cultures was also adversely influenced by incubation of the blood lysis mixture overnight before filtration. We conclude that this lysis filtration system is useful as an adjunct to conventional broth culture in selected patients in cases in which filtration can be carried out soon after collection.

Conjugal transferability of multiple resistance in Shigella strains.

Shigella strains isolated in Japan between 1971 and 1979 were surveyed for drug resistance and distribution of R plasmids. Of 2,510 strains, 89.3% were resistant to either one or various combinations of four drugs, tetracycline, chloramphenicol, streptomycin, and sulfanilamide. About 66% of the Shigella isolates were quadruply resistant. The frequency of isolation of R plasmids from quadruply resistant Shigella strains was the highest when compared with other strains resistant to various combinations of the four drugs. The conjugal transferability of 204 quadruply resistant strains isolated between 1977 and 1979 was tested by various mixed-culture methods. Among the total strains examined, 70.6% carried transferable resistance when tested by the conventional broth culture method, 90.2% transferred their resistance when, in addition the replica-plating method was used and 97.5% could transfer their resistance when the membrane filter method was also used. Although the remaining five strains could not transfer their resistance by any of the mixed culture methods, the drug resistance of four of the five strains was mobilized by the concomitant presence of F-tet or T-kan plasmid. These results indicate that almost all of the quadruple resistance in Shigella isolates was mediated by plasmid.

A Semiquantitative Culture Technic for Identifying Infection Due to Steel Needles Used for Intravenous Therapy

Using steel intravneous needles obtained from patients with hematologic malignancies, the authors evaluated the efficacy of a semiquantitative method for culturing vascular cannulas on solid medium, comparing it with conventional broth culture. Of 148 needles studied, 140 (95%) were negative on semiquantitative culture (less than 15 colonies on the plate) although 38 produced growth in broth or on the plate; none of these needles caused septicemia. Eight needles were positive on semiquantitative culture (greater than or equal to 15 colonies), and two of these caused septicemia (P = .002). Positive semiquantitative cultures were associated with local inflammation (P = .02). Semiquantitative culturing was equal to the broth method in sensitivity (100%) in the diagnosis of needle-related septicemia; specificity (96% vs. 92%) and the predictive value of a positive needle culture (25% vs. 14%) were both enhanced with the semiquantitative method. The semiquantitative technic differentiates infection from contamination and offers other major advantages compared with the broth method, and is recommended for culturing steel needles as well as plastic catheters.

A semiquantitative culture method for identification of catheter-related infection in the burn patient

A semiquantitative (SQ) method for culturing vascular catheters on solid media has been evaluated with 50 high-risk catheters from 6 patients with extensive second- and third-degree burns. The technique reliably differentiates catheter-related infection from contamination; a positive SQ culture (> 15 colonies) denotes local infection and a concentration exceeding 10 5 organisms per gram in the catheter wound, and with venous suppuration, within the vein. In this study, 16 of the 50 catheters (32%) were SQ culture-positive including all 5 catheters causative of septicemia ( P = 0.003). Confluent growth on the SQ plate was demonstrated in all three instances of suppurative phlebitis. The specificity and the predictive value of a positive catheter culture in diagnosis of catheter-related septicemia were substantially enhanced when compared with the conventional broth culture in this study in burn patients was associated with related septicemia at least 31% of the time. With the SQ technique, microbiologic identification and susceptibility testing of clinically significant isolates are accelerated. Knowledge of a positive SQ catheter culture in a burn patient with persistent sepsis can provide added impetus for diagnostic venotomy and definitive surgical therapy of suppurative phlebitis.