We performed an open, prospective, randomized clinical trial in 51 patients receiving mechanical ventilation for more than 72 h, in order to evaluate the impact of using either invasive (protected specimen brush [PSB] and bronchoalveolar lavage [BAL] via fiberoptic bronchoscopy) or noninvasive (quantitative endotracheal aspirates [QEA]) diagnostic methods on the morbidity and mortality of ventilator-associated pneumonia (VAP). Patients were randomly assigned to two groups: Group A patients (n = 24) underwent QEA, PSB, and BAL; Group B patients (n = 27) underwent only QEA cultures. Empiric antibiotic treatment was given according to the attending physician and was modified according to the results of cultures and sensitivity in Group A using PSB and BAL results and in Group B based upon QEA cultures. Bacteriologic cultures were done quantitatively for EA, PSB, and BAL. Thresholds of > or = 10(5), > or = 10(3), and > or = 10(4) CFU/ml were used for QEA, PSB, and BAL, respectively. Microbial cultures from Group A patients were positive in 16 (67%) BAL samples, 14 (58%) PSB samples, and 16 (67%) QEA samples. In Group B patients, QEA microbial cultures yielded positive results in 20 of 27 (74%) samples. In Group A, there was total agreement between culture results of the three techniques on 17 (71%) occasions. In five (21%) cases, QEA coincided with either BAL or PBS. In only two (8%) cases, QEA cultures did not coincide with either PSB or BAL. No cases of positive BAL or PSB cultures had negative QEA cultures. Initial antibiotic treatment was modified in 10 (42%) patients from Group A and in four (16%) patients from Group B (p < 0.05). The observed crude mortality rate was 11 of 24 (46%) in Group A, and 7 of 27 (26%) in Group B, whereas the adjusted mortality rates (observed crude minus predicted at admission) for Groups A and B were 29 and 10%, respectively. There were no statistically significant differences when comparing crude and adjusted mortality rates of Groups A and B. There were no differences in mortality between both groups when comparing pneumonia, considering together Pseudomonas aeruginosa and Acinetobacter spp. (Group A, 33% versus Group B, 27%). There were no differences between Groups A and B with regard to ICU stay duration and total duration of mechanical ventilation. In this pilot study, the impact of bronchoscopy was to lead to more frequent antibiotic changes with no change in mortality. Further studies with larger population samples are warranted to confirm these findings.
Of 342 patients with community-acquired pneumonia, 100 were diagnosed etiologically. In these patients, disease epidemiology, prognostic factors, and influence of antibiotic treatment were analyzed prospectively. Fifty-two patients were treated with a broad-spectrum antibiotic (ceftriaxone), and 48 received a medium-spectrum antibiotic (cefuroxime); some patients in each group also received erythromycin. Streptococcus pneumoniae was the most frequently isolated microorganism (43%), followed by Chlamydia pneumoniae (21%), Haemophilus influenzae (19%), and Mycoplasma pneumoniae (11%). Factors significantly associated with increased mortality were initially critical or poor clinical condition, involvement of two or more lobules, and complications. Prior administration of antibiotics was predictive of penicillin and erythromycin resistance in Streptococcus pneumoniae, but had no effect on the course of the disease. Eight patients died, 89 were cured, and three had recurrences; there was no significant difference in outcome between treatment groups, regardless of whether patients also received erythromycin. Increased knowledge of epidemiological, predictive, and prognostic factors can significantly improve early diagnosis of community-acquired pneumonia and facilitate the choice of appropriate antibiotic treatment, thereby helping to reduce morbidity and mortality.
A comparative study was carried out to evaluate the performances of different culture media for the recovery of Salmonella spp. from 1,000 routine samples of human stools. By direct plating we tested Salmonella-Shigella agar (SS), Hektoen enteric agar (HE), bismuth sulfite agar (BS), novobiocin-brilliant green-glycerol-lactose agar (NBGL) and SM-ID medium (SM), and after selenite enrichment, we tested all of the media except HE. C 8-esterase and oxidase tests were used for the screening of Salmonella spp. on SS and HE. The total number of Salmonella isolates from direct culture was 74, with respective sensitivities and positive predictive values (PPVs) of 78.4 and 61%, 64.9 and 18.7%, 36.5 and 34.2%, 55.4 and 20.7%, and 39.2 and 43.9% for NBGL, SS, HE, BS, and SMID, respectively. After enrichment, the total number of Salmonella isolates was 88. The respective sensitivities and PPVs obtained were 90.9 and 62.5%, 92 and 17%, 90.9 and 32% and 93.2 and 71.3% for NBGL, SS, BS, and SM, respectively. According to our results, NBGL in direct plating was the medium with the highest sensitivity with respect to the sensitivities of the other media, with significant statistical differences (P < 0.05). Likewise, the PPV for NBGL was also the highest (61%). After enrichment in selenite broth, the sensitivities of the four media tested were similar, with the best PPV obtained with SM (71.3%); this was followed by NBGL (62.5%). When C 8-esterase was used on SS or HE, the PPVs improved from less than 40% to about 100%.
The relative performance of five plating media [Rambach agar; salmonella-shigella (SS) agar, novobiocin-brilliant green-glycerol-lactose (NBGL), modified semisolid Rappaport-Vassiliadis medium (MSRV), and Salmonella Detection and Identification-2 (SM2)] and selenite broth (SB) subcultured in SS agar in the recovery of Salmonella spp. from 500 human stool specimens was evaluated. On Rambach agar and SS agar, the C8-esterase test was also used for selection of suspicious colonies. Eighty-one samples were positive for salmonellae on at least one of the six media. Sensitivities and specificities of MSRV, SB, NBGL, SS, Rambach agar, and SM2 were 95.1 and 98.1%, 87.6 and 99.8%, 79 and 91.9%, 69.1 and 99.3%, 56.8 and 96.9%, and 54.3 and 92.4%, respectively. There were statistically significant differences between MSRV and NBGL, Rambach agar, SS agar, and SM2 (p < 0.005), between SB and SS agar, Rambach agar, and SM2 (p < 0.05), and between NBGL and SM2 and Rambach agar (p < 0.005). The greatest number of isolates was recovered with MSRV, whose performance surpassed that of enrichment in selenite broth, probably because the subcultures were not repeated on MSRV. This hypothesis is now under investigation. The specificity of each of the five solid media was greater than 90%.
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