Angela von Nowakonski

Nested-PCR using MPB64 fragment improves the diagnosis of pleural and meningeal tuberculosis

Fluids in which Mycobacterium tuberculosis are seldom found, such as pleural and cerebrospinal liquids, are good candidates to be studied using PCR techniques. We detail our experience with a PCR assay applied to pleural and cerebrospinal fluids using the primer MPB64. Seventy three specimens were analyzed: 30 pleural fluids (PF), 26 pleural biopsies (PB) and 17 cerebrospinal fluids (CSF). The gold standard for the diagnosis of tuberculous meningitis was the positive culture for M. tuberculosis in CSF. Tuberculous pleural effusion was diagnosed when cultures of PF and/or PB were positive for M. tuberculosis, or the PB histology showed granulomas. Our results, compared to the gold standards employed, showed a sensitivity of 70%, specificity of 88%, positive predictive value of 82% and negative predictive value of 80%. The high specificity of the MPB64 fragment while still retaining a good sensitivity makes it very well suited for pleural and cerebrospinal tuberculosis diagnosis.

Evaluation of the in vitro activity of cefepime compared to other broad-spectrum cephalosporins against clinical isolates from eighteen Brazilian hospitals by using the Etest.

The in vitro activity of cefepime was compared to that of ceftazidime, ceftriaxone, and cefotaxime in a multicenter study involving 10 clinical microbiology laboratories and clinical isolates from 18 Brazilian hospitals from 7 cities (4 states). A total of 982 isolates consecutively collected between December 1995 and March 1996 were susceptibility tested by using Etest and following the NCCLS procedures for agar diffusion tests. The cefepime spectrum was broader than that of the other broad-spectrum cephalosporins against both Gram-negative rods and Gram-positive cocci. Cefepime was particularly more active against Enterobacter sp. (MIC90, 2 micrograms/ml), Serratia sp. (MIC90, 2 micrograms/ml) and oxacillin-susceptible Staphylococcus aureus (MIC90, 3 micrograms/ml). Against Pseudomonas aeruginosa, cefepime (MIC90, 16 micrograms/ml) was slightly more active than ceftazidime (MIC90, 32 micrograms/ml) and 8- to 16-fold more active than ceftriaxone of cefotaxime (MIC90, > 256 micrograms/ml). Our results show that nosocomial bacteria, especially Gram-negative rods, have a high rate of cephalosporin resistance in Brazil. However, part of these resistant bacteria remains susceptible to cefepime. The Etest was shown to be an excellent method for multicenter studies of the in vitro evaluation of new antimicrobial agents.

Molecular epidemiology of a nosocomial outbreak due to Enterobacter cloacae and Enterobacter agglomerans in Campinas, São Paulo, Brazil

A total of 73 isolates (57 Enterobacter cloacae and 16 Enterobacter agglomerans), recovered during an outbreak of bacteremia in the Campinas area, São Paulo, Brazil, were studied. Of these isolates, 61 were from parenteral nutrition solutions, 9 from blood cultures, 2 from a sealed bottle of parenteral nutrition solution, and one was of unknown origin. Of the 57 E. cloacae isolates, 54 were biotype 26, two were biotype 66 and one was non-typable. Of 39 E. cloacae isolates submitted to ribotyping, 87.2% showed the same banding pattern after cleavage with EcoRI and BamHI. No important differences were observed in the antimicrobial susceptibility patterns among E. cloacae isolates exhibiting the same biotype, serotype and ribotype. All E. agglomerans isolates, irrespective of their origin, showed same patterns when cleaved with EcoRI and BamHI. The results of this investigation suggest an intrinsic contamination of parenteral nutrition solutions and incriminate these products as a vehicle of infection in this outbreak.

Low prevalence of vancomycin resistant enterococci colonization in intensive care patients in a Brazilian teaching hospital

Vancomycin-resistant enterococci (VRE) are important pathogens involved in nosocomial infections. Colonization precedes infection and the number of colonized individuals is about 10 times higher than the number of infected patients. We examined VRE colonization in two intensive care units from October 2003 to June 2004. Perirectal swab specimens were obtained from all patients, starting on the 5th day after admission, and then weekly. A total of 249 swabs were obtained from 112 patients. Nine patients had VRE-positive swabs, giving a positive rate of 8.0%. The rate of patients colonized by V-R E. faecalis was 1.8% (n=2), 4.5% by V-R E. gallinarun (n=5) and 1.8% by V-R E. casseliflavus (n=2). No V-R E. faeciun was isolated. None of the patients that had been colonized by VRE were found to be infected by these pathogens. In summary, a low prevalence of colonization by VRE was found in our institution. Only a structured surveillance program, based on active searching, was able to detect this low number of cases.

Listeriosis and AIDS: case report and literature review

Listeriosis is a not uncommon infection in humans, usually associated with immunodeficient states and with newborns. However, relatively few cases have been reported in HIV-infected patients. This scarcity of reported cases has aroused interest in the association of listeriosis and AIDS. In this paper we present a case of meningitis and septicemia caused by Listeria monocytogenes in a female patient with AIDS. A review of recent medical literature indicates that association of listeriosis and AIDS may be more common than it seems. Recent research in host-parasite interaction in listerial infection suggests an important role for tumor necrosis factor (TNF) and for integralin, a bacterial protein, in modulating listerial disease in AIDS patients. Inadequate diagnosis may be in part responsible for the scarcity of reports.

Microbiological characteristics of sepsis in a University hospital

BackgroundMicrobiological characteristics of sepsis and antimicrobial resistance are well studied, although in State University of Campinas, no data has been published yet.MethodsThe main agents related to sepsis and antimicrobial resistance were analyzed. The blood culture records requested from 4,793 hospitalized patients were analyzed. The samples were processed using the Bact/Alert® system for agent identification and antimicrobial susceptibility.ResultsA total of 1,017 patients met the inclusion criteria for a sepsis diagnosis, with 2,309 samples tested (2.27 samples/patient). There were 489 positive samples (21% positive) isolated from 337 patients (33.13%), but more rigorous criteria excluding potential contaminants resulted in analysis being restricted to 266 patients (315 agents). The prevalent microorganisms were coagulase negative Staphylococcus (CNS) (15.87%), Escherichia coli (13.0%), Staphylococcus aureus (11.7%), Klebsiella pneumoniae (9.8%), Enterobacter sp (9.5%), Acinetobacter baumannii (9.2%), Pseudomonas aeruginosa (5.7%) and Candida sp (5.1%). Examining antimicrobial resistance in the agents revealed that 51% of the S. aureus isolates were methicillin-resistant S. aureus (MRSA) and 80% of the CNS isolates were oxacillin-resistant. For A. baumannii, the ideal profile drugs were ampicillin sulbactam and piperacillin/tazobactam, and for P. aeruginosa, they were piperacillin/tazobactam and ceftazidime. Enterobacteria showed on average 32.5% and 35.7% resistance to beta-lactams and ciprofloxacin, respectively. When all Gram-negative bacteria were considered, the resistance to beta-lactams rose to 40.5%, and the resistance to ciprofloxacin rose to 42.3%.ConclusionsEighty percent of the agents identified in blood cultures from patients with sepsis belonged to a group of eight different agents. For empirical treatment, carbapenems and vancomycin unfortunately still remain the best therapeutic choice, except for A. baumannii and P. aeruginosa, for which piperacillin/tazobactan is the best option.