The importance of prevalence and pre-test probability on the microbiological diagnosis of SARS-CoV-2: the case of Spain in 2020.

OBJECTIVE: The aim of this work was to estimate the conditioned probability for the diagnosis of SARS-CoV-2 infection with reverse transcription polymerase chain reaction (RT-PCR), viral antigen rapid diagnostic tests (Ag-RDT), and antibody detection tests depending on the prevalence in the specific healthcare settings in Spain in 2020, and on the pre-test probability (PTP) according to the clinical situation, age and unknown or close contacts of the patient. METHODS: Performance parameters of tests were obtained from literature. Prevalence data and PTP were obtained from Spanish sources and a survey, respectively. The post-test probability is the positive predictive value (PPV) when test is positive. For negative result, we also calculated the probability of having the infection (false negatives). RESULTS: For both RT-PCR and viral Ag-RDT, the lowest PPV values were for the population screenings. This strategy proved to be useful in ruling out infection but generates a high number of false positives. At individual level, both tools provided high PPV (≥ 97%) when the PTP values are over 35%. In seroprevalence studies, though the specificity of IgG alone tests is high, under low seroprevalence, false positives cannot be avoided. Total antibodies tests are useful for diagnosis of COVID-19 in those doubtful cases with RT-PCR or Ag-RDT tests being repeatedly negative. CONCLUSIONS: The interpretating of results depends not only on the accuracy of the test, but also on the prevalence of the infection in different settings, and the PTP associated to the patient before performing the test.

[The prevalence and pharmacological cost of Parkinson's disease in Spain]. / Prevalencia y coste farmacológico de la enfermedad de Parkinson en España.

INTRODUCTION: Parkinson's disease is the second most frequent neurodegenerative disease. AIM: To analyze the dispensation of antiparkinsonian agents in Spain and to estimate the Parkinson's disease prevalence. MATERIALS AND METHODS: Dispensation of antiparkinsonian agents were studied in Spain during two years (October 1998 to September 2000). Results were expressed in defined daily dosages per 1,000 inhabitants per day (DID). Levodopa's DID was used to estimate the prevalence of the disease. The cost per 1,000 inhabitants per day (CID) and the daily treatment cost was also valued. RESULTS: The most frequently used drugs are levodopa, biperiden and selegiline. The total cost reached values of 116,346,589.30 euros during the study period. The CID was 4,14 euros. It was very high the daily treatment cost of pramipexol and entacapone. The prevalence of Parkinson's disease is considered in 1.7 per 1,000 inhabitants in Spain. There is an important geographical variability; regions as Castilla-Leon, Galicia and La Rioja have a higher prevalence than Andalucia or Murcia. The number of patients in Spain can be considered in 69,571 people. CONCLUSION: There are some differences between the autonomous communities in the antiparkinsonian drugs' utilization.

Characterization and distribution in normal and tumoral human tissues of breast cancer-associated antigen defined by monoclonal antibody 7B10.

Monoclonal antibody 7B10, raised against the human breast cancer cell line T47D, identifies an antigen found in human breast carcinomas and in normal breast. Western blot and immunoprecipitation studies detected a Mr 76,000 antigen in cytosol, cell membrane, and cell culture supernatants of T47D cells. 7B10 binding to T47D cell extracts was affected by proteolytic digestion with protease type VI, trypsin, and subtilisin while it was not altered by neuraminidase digestion. Adsorption of breast cancer cell line extracts with concanavalin A reduced 7B10 immunoreactivity more than 70%. These results suggest that the antigen is a glycoprotein and that the epitope does not contain sialic acid. 7B10 was reactive with neither human milk fat globule membrane, nor skimmed milk, nor the milk-derived HBL 100 cell line. Conversely binding was detected in more than 50% of normal breast epithelial cells in culture. 7B10 immunostaining was positive on frozen sections of normal breast and nonmalignant mastopathies in 30 to 90% cells. In frozen sections of other normal tissues, 7B10 immunoreactivity was detected only in colon, apocrine glands of skin, parotid ducts, and luteal phase endometrium, confirming previous data on paraffin sections. Strong, homogeneous immunostaining was observed on frozen sections of intraductal and invasive lobular breast carcinomas (100% of cases), while more heterogeneous staining was found on invasive ductal carcinomas. Colon and rectal carcinomas, one carcinoma of the esophagus, and some cells in serous ovarian carcinomas also showed 7B10 reactivity. Immunoblotting of the 7B10-immunoreactive fraction isolated by Sepharose CL-6B chromatography of a breast carcinoma tissue sample extract identified the Mr 76,000 antigen, which was also detected in several breast cancer specimens, in colon adenocarcinomas, and in serous ovarian carcinoma fresh tumor extracts. The Mr 76,000 glycoprotein described here represents a breast cancer-associated antigen previously undescribed, mainly expressed in normal breast and breast tumors.

Characterization and distribution in human tissues of a glycoproteic antigen defined by monoclonal antibody 1BE12 raised against the human breast cancer cell line T47D.

Spleen cells from inbred Biozzi mice, immunized against the human breast cancer cell line T47D, were fused with murine myeloma SP2O cells to generate monoclonal antibodies. One of these, 1BE12, of IgM isotype, reacted with five of six human breast tumor cell lines, while no binding was detectable with normal lymphocytes, RBC, or fibroblasts. The antigen recognized by monoclonal antibody 1BE12 was localized on the surface of T47D and MCF7 cells and was detected in cell-free supernatants of cultures. The antigen was found also on the surface of milk secretory cells. Immunohistochemical staining of frozen and paraffin-embedded sections of human tissues showed apical polarized reactivity in normal breast glands, while in all breast cancers staining was either cytoplasmic or membranous and heterogeneously distributed. Immunostaining was also observed in some other normal epithelia, including salivary gland, gastroduodenal mucosa, exocrine pancreas, and cervix. The antigen was not detectable in secretory endometrium, whereas proliferative endometrium was strongly stained. Colon carcinoma, and cancers of the bladder and endometrium were strongly reactive. No staining was detected in melanoma, lymphoma, mesothelioma, non-small cell lung carcinoma, and thyroid, renal, and ovarian carcinomas. Lectin absorption of MCF7 membrane extracts reduced 1BE12 binding. A large reduction in 1BE12 reactivity was observed after digestion of T47D and MCF7 membrane extracts with proteases. Treatment with sodium periodate resulted in complete loss of antigenicity, while neuraminidase treatment did not affect 1BE12 binding. These findings suggest that the 1BE12 epitope is expressed on the carbohydrate moiety of a glycoprotein and does not contain sialic acid. Immunoblotting of the perchloric acid-soluble fraction of MCF7 membrane extracts after electrophoresis in 1% agarose detected the antigen as a high molecular weight species (Mr greater than 900,000). The antigen was purified by perchloric acid extraction of MCF7 membrane preparations followed by affinity chromatography on 1BE12 antibody coupled to Sepharose-4B and gel exclusion fast protein liquid chromatography. No reactivity of the purified material was found with monoclonal antibodies directed against human milk fat globule membrane-associated mucins HMFG1 and DF3.

Crystallization and preliminary crystallographic analysis of a tetrameric isolectin from Vicia villosa, specific for the Tn antigen.

Isolectin B4 isolated from Vicia villosa seeds is specific for the Tn antigen, a carcinoma-associated molecular marker. Crystals of the isolectin grown in the presence of carbohydrate are tetragonal, space group P4(1) (or P4(3), with a = 91.3 A, c = 151.7 A and one tetramer in the asymmetric unit. The crystals diffract X-rays to 2.8 A resolution and are suitable for high-resolution structural analysis.

[Dispensation and cost of antimicrobials in Spain (1998-2000)]. / Dispensación y coste de antimicrobianos en España (1998-2000).

The aim of this study was to analyze the dispensation of anti-infectives for systemic use, excluding immune sera and immunoglobulins and vaccines, made in all of Spain's pharmaceutical offices in a two-year period and to analyze their pharmacological cost. A retrospective pharmacoepidemiological study was made of dispensations in Spain's pharmaceutical offices for medicines belonging to the J01, J02, J04 and J05 subgroups. The dispensations were quantified as defined daily doses per 1,000 inhabitants per day (DID). The economic cost of the dispensing was expressed in absolute terms and as CID (cost per 1,000 inhabitants per day). The total DID of anti-infective drugs was 32.11 (30.70 for antibacterials, 0.53 antimycotics, 0.73 for antimicrobacterials and 0.16 for antivirals). In the J01 subgroup the most frequently used were penicillins, macrolides, cephalosporins and quinolones. And the most frequently used drugs were amoxicillin, amoxicillin and clavulanic acid, clarithromycin, cefuroxime axetil and ciprofloxacin. The total cost was 1,403,462,770 euros, and the CID was 47.18 euros.

Amino acid sequence and three-dimensional structure of the Tn-specific isolectin B4 from Vicia villosa.

The partial amino acid sequence of the tetrameric isolectin B4 from Vicia villosa seeds has been determined by peptide analysis, and its three-dimensional structure solved by molecular replacement techniques and refined at 2.9 A resolution to a crystallographic R-factor of 21%. Each subunit displays the thirteen-stranded beta-barrel topology characteristic of legume lectins. The amino acid residues involved in metal- and sugar-binding are similar to those of other GalNAc-specific lectins, indicating that residues outside the carbohydrate-binding pocket modulate the affinity for the Tn glycopeptide. Isolectin B4 displays an unusual quaternary structure, probably due to protein glycosylation.

Analysis of the fine specificity of Tn-binding proteins using synthetic glycopeptide epitopes and a biosensor based on surface plasmon resonance spectroscopy.

Using synthetic Tn (GalNAc-O-Ser/Thr) glycopeptide models and a biosensor based on surface plasmon resonance spectroscopy we have determined that isolectin B4 from Vicia villosa (VVLB4) binds to one Tn determinant whereas the anti-Tn monoclonal antibodies 83D4 and MLS128 require at least two Tn residues for recognition. When an unglycosylated amino acid is introduced between the Tn residues, both antibodies do not bind. MLS128 affinity was higher on a glycopeptide with three consecutive Tn residues. These results indicate that Tn residues organized in clusters are essential for the binding of these antibodies and indicate a different Tn recognition pattern for VVLB4.

Neutralization epitopes on HIV pseudotyped with HTLV-I: conservation of carbohydrate epitopes.

One mechanism for expanding the cellular tropism of human immunodeficiency virus (HIV) in vitro is through formation of phenotypically mixed particles (pseudotypes) with human T lymphotropic virus type I (HTLV-I). In this study we found that pseudotypes allow penetration of HIV particles into CD4-negative cells, previously nonsusceptible to HIV infection. The infection of CD4-negative cells with pseudotypes could be blocked with anti-HTLV-I serum but failed to be significantly inhibited with anti-HIV serum or a V3-neutralizing anti-gp120 monoclonal antibody. This may represent a possibility for pseudotypes to escape neutralization by the immune system in vivo. Previous reports have suggested that carbohydrate structures may be conserved neutralization epitopes on retroviruses. In this study, the neutralizing capacity of lectins and anti-carbohydrate monoclonal antibodies was found to block infection by cell-free pseudotypes in CD4-negative cells. We suggest that although viral cofactors might expand the tropism of HIV in vivo, HIV and HTLV-I seem to induce common carbohydrate neutralization epitopes.

Molecular detection of cancer cells in bone marrow and peripheral blood of patients with operable breast cancer. Comparison of CK19, MUC1 and CEA using RT-PCR.

We have compared three different RT-PCR procedures to measure cytokeratin 19 (CK19), carcinoembryonic antigen (CEA) and mucin MUC1 gene expression in order to determine their diagnostic value in detecting tumour cells in bone marrow aspirates of patients with operable breast cancer. In an experimental model, the best sensitivity was observed for CK19 and MUC1 RT-PCR assays, although only the CEA and CK19 assays showed good specificity. The study of 42 patients showed that a 'CK19 positive/CEA positive' RT-PCR assay in bone marrow correlated positively with a positive axillary lymph node status (N(0) versus N(1-3), P<0.05). Both assays were also positive in 17% of node negative patients. RT-PCR assays were more sensitive in bone marrow than in peripheral blood. Our results suggest that CK19 and CEA RT-PCR assays are powerful methods for detecting disseminated breast cancer cells. A larger study with long-term follow-up is required in order to clarify their clinical usefulness.

Development of an immuno-lectin-enzymatic assay for the detection of serum cancer-associated glycoproteins bearing Tn determinant.

We report the development of an immuno-lectin-enzymatic assay (CA83.4) with the purpose of quantifying serum glycoproteins bearing Tn determinant (GalNAc alpha-O-Ser/Thr). An anti-Tn monoclonal antibody (83D4) is bound to the solid phase in order to capture glycoproteins. After the addition of a test sample, we used biotinylated isolectin B4 from Vicia villosa and avidin-peroxydase to act as a detection system. The linear relationship between CA83.4 determinations and the serum dilutions, the reproducibility of the dosage in intra- and inter-assay, and the specificity of the test for the N-acetylgalactosamine residue in a-glycosidic O-linkages, demonstrated the reliability of this trial. Self-recognition of Vicia villosa B4 molecules (K-D: 0.73x10(-6) M determined using biosensor technology) could determine an additional step of signal amplification in this assay. Using 0.25 units/ml of CA83.4 antigen as the cut-off level, higher values were found in 25/49 patients with breast cancer, 8/13 with colorectal carcinoma, 3/11 with lung cancer, but in none of the 49 patients with non-malignant diseases nor in 97 healthy controls. This first report on soluble Tn-glycoprotein detection assays suggests that Tn-glycoproteins are specific serological tumor markers and we believe that they could represent a valuable tool in the diagnosis of cancer.

Immunocytological analysis of the Tn associated antigen 83D4 in serous effusions from patients with cancer: comparison with Tn soluble glycoprotein.

AIMS: To determine whether the monoclonal antibody (MoAb) 83D4, previously shown to be highly specific for carcinoma cells, can be used as an immunocytological marker to discriminate between benign and malignant cells in serous effusions; and to test for a correlation between expression of the antigen reacting with MoAb 83D4 on effusion cells and the amount of soluble 83D4 antigen in effusion fluids. METHODS: Thirty three pleural and 23 peritoneal effusions from 56 cancer patients with metastatic disease were tested for the presence of Tn associated 83D4 antigen by immunocytochemical staining, and for the presence of soluble antigen in supernatants. The patients had undergone various chemotherapy and radiation therapy protocols. RESULTS: As a result of the various types of treatment, the cytological characteristics of the cells were often modified and the antigenic epitopes may have been altered. Positive staining for 83D4 MoAb was obtained in 36 (97%) of the 37 malignant effusions, eight (73%) of 11 suspect effusions, and three (38%) of the eight apparently benign effusions (free of malignant cells). In these latter cases, cytological reassessment showed a few suspect cells in two cases. 83D4 soluble antigen was detected in 30 of 37 malignant effusions (81%), five of 11 suspected infusions (46%), and five of eight apparently benign effusions (63%). CONCLUSIONS: Immunocytochemical staining with anti-83D4 antibody is useful for differentiating reactive or atypical mesothelial cells from epithelial cells, especially in breast cancer effusions.

Monoclonal antibody 83D4 immunoreactivity in human tissues: cellular distribution and microcytophotometric analysis of immunoprecipitates on tissue sections.

Immunocytochemical assays were performed on cell cultures as well as on a wide range of human tissues using a monoclonal antibody, MAb 83D4, produced by a murine hybridoma generated by immunization with a cell suspension from a paraffin block of human breast carcinoma tissue. Frozen breast tissue samples (n = 49) were compared to fixed and paraffin-embedded samples (n = 62). Paraffin sections (n = 194) from a variety of human tissues were compared to breast immunoreactivity. Immunoprecipitates, resulting from positive reactions between 83D4 and Avidin Biotin Peroxidase, were evaluated by computer-assisted microcytophotometry (SAMBA). In some frozen breast samples (n = 27), 83D4 antigen distribution was correlated with tumor cell DNA index, ploidy balance, growth fraction (Ki67), hormone receptor (ER, PR) antigenic sites, NORsAg and oncoprotein pHER-2/neu cell content. MAb 83D4 reacted with 3 breast cancer cells lines (MCF7, T47D and H466B) but not with normal epithelial breast cells in culture. The immunostaining in frozen paraffin sections from breast were similar. Like most normal tissues, normal breast did not react with 83D4. Cellular MAb 83D4 antigen concentration increases with the degree of malignancy but is independent of DNA nuclear content, ER, PR, growth fraction and pHER-2neu in cancers. These results suggested that routine immunohistochemical procedures using MAb 83D4 could facilitate the grading of breast cancer, in particular by allowing detection of microvascular invasions in the breast as well as at a distance and of blood-born micrometastases, especially in bone marrow.

Detection of rare human breast cancer cells. Comparison of an immunomagnetic separation method with immunocytochemistry and RT-PCR.

BACKGROUND: The detection of occult carcinoma cells in patients with breast cancer may aid determination of prognosis and the development of new therapeutic approaches. In this study, we report a new method to detect rare human breast cancer cells, which combines an immunomagnetic separation (IMS) procedure with cytokeratin 19 (CK 19) immunostaining. MATERIALS AND METHODS: Four monoclonal antibodies (MAb) previously characterized against cell surface antigens (1BE12, ED8, 7B10 and 83D4), were evaluated for IMS optimization. Immunoseparated epithelial cells were identified using a MAb against CK 19. We compared the IMS procedure with the immunocytochemistry (ICC) and the RT-PCR for CK 19 on an "in vitro" experimental model. RESULTS: The best results in IMS procedures were obtained using MAbs 1BE12 (directed against Lewis y antigen) and ED8 (directed against MUC 1). In reconstitution experiments, using several ratios of T47D cells mixed with peripheral-blood mononuclear (PBMN) cells, the IMS procedure reliably detects one mammary carcinoma cell in 5 x 10(5) PBMN cells, whereas the ICC detects up to one T47D cell per 10(5) PBMN cells. The best sensitivity was observed with the RT-PCR (up to one T47D cell per 10(6) PBMN cells). We found the same high specificity with the three methods evaluated. CONCLUSIONS: The IMS procedure using MAbs 1BE12 or ED8 associated with CK 19 immunostaining is a specific, sensitive, and feasible method for the detection of rare human breast cancer cells. This method proved to be better than the ICC staining but its sensitivity was lower than that of RT-PCR for CK 19.

Lactate dehydrogenase activity and its isoenzymes in concentric layers of adult bovine and calf lenses.

The activity of lactate dehydrogenase (LDH) and its isoenzyme pattern were studied in four concentric layers of adult bovine and calf lenses. In both groups the specific activity of the total LDH diminished progressively toward the internal nuclear layer; the decrease was greater in the adult lenses. The enzyme activities in the cortical layers of the calf lens were lower than in the adult lens, but in the inner nuclear layers, the opposite was found. All of the 5 LDH isoenzymes were found in each layer. In both groups of animals the LDH1 isoenzyme prevailed, followed by LDH2. No differences were found in the percentage of each isoenzyme in the different lens layers. The differences in the activitie(s) of LDH found may be due to post-translational or post-synthetic modifications which may occur during the aging process.

Production of a monoclonal antibody as immunohistochemical marker on paraffin embedded tissues using a new immunization method.

This report describes a method for the production of murine monoclonal antibodies (MAbs) against cellular antigens preserved during formol fixation and paraffin embedding of human tissues in an attempt to select markers that would be useful in immunopathology. Hybridomas were prepared using spleen cells from mice immunized with cell suspensions obtained from formalin-fixed paraffin block sections of a human breast carcinoma. A monoclonal antibody 83 D4 was selected, which was reactive with paraffin embedded breast carcinoma tissues, but not with normal breast. The reactive antigen has a high molecular weight (400-1000 kD) and was detected on the cell surface of live human breast cancer cell lines and on frozen tissues sections. These results demonstrate that the MAb 83 D4 identifies a native breast tumor associated epitope conserved during tissue fixation and embedding and could be used as an immunohistochemical marker.

Molecular cloning of a monoclonal anti-tumor antibody specific for the Tn antigen and expression of an active single-chain Fv fragment.

We report here the first amino acid sequence of an anti-Tn monoclonal antibody raised against human breast cancer cells and show that a single chain Fv fragment of this IgM retains the Tn-binding specificity as defined by functional assays with asialo-OSM and membrane extracts from MCF-7 cells. Sequence comparisons and molecular modeling of 83D4 indicate that the antibody combining site displays a cavity-like feature primarily defined by the CDR H1 and H2 loops. This pocket could accommodate a single Tn molecule, thus, suggesting a structural explanation for the predominant expression of a particular VH gene segment in a group of antibodies that recognize tumor-associated antigens arising from an aberrant O-glycosylation.

Two monoclonal antibodies identify antigens preferentially expressed on normal human breast cells versus breast cancer cells.

In order to obtain antibodies with specificity toward normal mammary epithelial antigenic determinants, we immunized BALB/c mice with normal milk cells and screened the hybridomas against an undifferentiated breast cancer cell line H466B, peripheral blood lymphocytes and normal fibroblasts. Two hybridomas were generated, which produced BA6 (IgG1) and CA4 (IgM) monoclonal antibodies (MAbs). These MAbs did not react with 5 breast cancer cell lines. In cryostat sections of normal human breast tissue, BA6 was reactive with 6/6 and CA4 was reactive with 12/13 specimens both showing an apical staining of epithelial cells. Conversely staining of malignant cells in breast cancer biopsies was observed in 4/33 specimens with BA6 and in 4/19 specimens with CA4. Computerized image analysis (SAMBA) of immunostained sections showed homogeneous distribution of staining, with a high percentage of stained cell surfaces in normal breast (mean percentages of positive surfaces : BA6 : 75% and CA4 : 82%) while, in malignant samples, staining was heterogeneous, with a mean percentage of positive surface of 25% for BA6 and 12% for CA4. Both MAbs reacted strongly with human milk fat globule membranes (HMFGM) and skimmed milk. FPLC size exclusion chromatography of skimmed milk showed that CA4 and BA6 reactive materials eluted in distinct peaks in high molecular weight ranges. Electrophoretic separation of HMFGM followed by CA4 staining detected a high molecular weight reactive band (Mr 380-600 kDa). CA4 and BA6 reactivity was reduced by protease treatment of the antigen but was not affected by neuraminidase digestion, by methanol extraction or by Na-metaperiodate oxidation. After perchloric acid treatment of HMFGM, BA6 activity was lost while the CA4 activity was found in the soluble fraction. The results reported suggest that the two MAbs identify two distinct novel epitopes of normal breast cells.

Production and functional characterization of two mouse/human chimeric antibodies with specificity for the tumor-associated Tn-antigen.

In this work, we have constructed two functional mouse/human chimeric antibodies (IgMkappa and IgG1kappa isotypes) by inserting genomic DNA fragments encoding VH and Vkappa variable regions of the murine monoclonal antibody IgMK-83D4 into mammalian expression vectors containing human mu, gamma1, and kappa constant exons, and by transfecting them into the nonsecreting mouse myeloma X-63 cell line. In previous works, we have demonstrated that 83D4 murine mAb reacts with Tn determinant (GalNAcalpha-O-Ser/Thr) expressed in 90% of breast, ovary, and colon carcinomas. Both expressed chimeric antibodies were purified from the transfected cell line supernatant by affinity chromatography, and their reactivities against Tn antigen were confirmed by ELISA on asialo ovine submaxilar mucin and immunofluorescence studies on MCF-7 breast carcinoma cell line. We have demonstrated by gel filtration chromatography, that the principal secreted forms were monomers for IgG1kappa and pentamers for IgMkappa. The binding affinities of these chimeric antibodies against synthetic Tn glycopeptides, were evaluated by surface plasmon resonance showing an affinity constant similar to that of 83D4 native antibody for IgMkappa and a lower affinity constant for IgG1kappa chimeric antibody. On the other hand, the replacement of mouse C regions with human C regions confers both chimeric antibodies the ability to activate human complement. These mouse/human chimeric antibodies should be much less immunogenic and could play an important role in the lysis of tumor cell expressing Tn-antigen. Therefore, these anti-Tn chimeric antibodies could be considered as potential tools for human in vivo studies.

[Evolution of antimicrobial use during the years 1996-2000 in a general hospital. A detailed ICU study]. / Evolución de la utilización de antimicrobianos durante los años 1996-2000 en un hospital general. Estudio pormenorizado de la UCI.

PURPOSE: Antimicrobials are a mayor part of hospital pharmacy budgets and must be considered in resource planning and spending projections. This study describes the profile of antibiotic use at a medium-sized hospital (by examining the ICU separately) and analyses its evolution over the period 1996-2000. METHODS: Descriptive and retrospective study. Pharmacy records were reviewed to identify oral and parenteral antimicrobial agents administered to inpatients. Results were expressed in Daily Defined Doses (DDD) per 100 stays and day. RESULTS: During the five-year study period 176.162 DDD / 100 s-d of antibiotics were consumed in the ICU, whereas in the rest of the hospital usage was much lower (54.540 DDD / 100 s-d). Aminoglycosides, cephalosporins, penicillins, glycopeptides and carbapenems were the most commonly used groups of antimicrobials in the ICU, and penicillins, cephalosporins, trimethoprim/sulfonamide combinations, aminoglycosides and quinolones in the rest of the hospital. CONCLUSIONS: ICUs have some special features which make them different to the rest of inpatient areas. Because of that fact we consider important to study this specific patient-care area separately.