Post-surgical mediastinitis due to carbapenem-resistantEnterobacteriaceae: Clinical, epidemiological and survivalcharacteristics

Invasive infections due to carbapenem-resistant Enterobacteriaceae (CRE),including polymyxin-resistant(PR-CRE) strains, are being increasingly reported. However, there is a lack of clinical data for several life threatening infections. Here we describe a cohort of patients with post-surgical mediastinitis due to CRE,including PR-CRE. This study was a retrospective cohort design at a single cardiology centre. Patients with mediastinitis due to CRE were identified and were investigated for clinically relevant variables. Infecting isolates were studied using molecular techniques. Patients infected with polymyxin-susceptible CRE(PS-CRE) strains were compared with those infected with PR-CRE strains. In total, 33 patients with CRE mediastinitis were studied, including 15 patients (45%) with PR-CRE. The majority (61%) were previously colonised. All infecting isolates carriedblaKPC genes. Baseline characteristics of patients with PR-CRE mediastinitis were comparable with those with PS-CRE mediastinitis. Of the patients studied, 70% received atleast one agent considered active in vitro and most patients received at least three concomitant antibiotics. Carbapenem plus polymyxin B was the most common antibiotic combination (73%). Over 90% of patients underwent surgical debridement. Overall, in-hospital mortality was 33% and tended to be higherin patients infected with PR-CRE (17% vs. 53%; P = 0.06). In conclusion, mediastinitis due to CRE, includingPR-CRE, can become a significant challenge in centres with CRE and a high cardiac surgery volume. Despite complex antibiotic treatments and aggressive surgical procedures, these patients have a highmortality, particularly those infected with PR-CRE...

A space–time model for carbapenemase-producing Klebsiellapneumoniae (KPC) cluster quantification in a high-complexityhospital

A retrospective space–time permutation model with non-Euclidean distance criteria was appliedwithin a high-complexity hospital setting to quantitatively explore cluster patterns of 273 patientsinfected with or colonized by carbapenemase-producing Klebsiella pneumoniae during 4 years.Results were compared to standard nosocomial active-surveillance methods. Two clusters wereidentified in the period, suggesting that space–time strategies for cluster quantification withinconfined environments may be useful.

Assessing the diversity of the virulence potential of Escherichia coli isolated from bacteremia in São Paulo, Brazil

Most of the knowledge of the virulence determinants of extraintestinal pathogenic Escherichia coli (ExPEC) comes from studies with human strains causing urinary tract infections and neonatal meningitis and animal strains causing avian colibacillosis. In this research, we analyzed the phylogenetic background, the presence of 20 ExPEC virulence factors, and the intrinsic virulence potential of 74 E. coli strains isolated in São Paulo, Brazil, from 74 hospitalized patients (43 males and 31 females) with unknown-source bacteremia. Unlike other places in the world, the bacteremic strains originated equally from phylogroups B2 (35%) and D (30%). A great variability in the profiles of virulence factors was noted in this survey. Nevertheless, 61% of the strains were classified as ExPEC, meaning that they possessed intrinsic virulent potential. Accordingly, these strains presented high virulence factor scores (average of 8.7), and were positively associated with 12 of 17 virulence factors detected. On the contrary, the non-ExPEC strains, isolated from 39% of the patients, presented a generally low virulence capacity (medium virulence factor score of 3.1), and were positively associated with only the colicin cvaC gene. These results show the importance of discriminating E. coli isolates that possess characteristics of true pathogens from those that may be merely opportunistic in order to better understand the virulence mechanisms involved in extraintestinal E. coli infections. Such knowledge is essential for epidemiological purposes as well as for development of control measures aimed to minimize the incidence of these life-threatening and costly infections.

Evaluation of the in vitro Activity of Two Fourth-Generation Cephalosporins Against Bacterial Samples Isolated From Patients in Several Brazilian Hospitals.

Cefpirome and cefepime are two fourth-generation cephalosporins recently introduced in Brazil. They have a very similar range of in vitro antimicrobial activity, but some differences have been noticed. The goal of this study was to compare the in vitro activity of cefpirome and cefepime against bacterial samples isolated in Brazilian hospitals. We studied 931 samples taken from hospitalized patients between April and June, 1998. The minimum inhibitory concentration (MIC) was determined by the Etest method. The potency of cefpirome was similar to that of cefepime, except against enterococci and coagulase-negative staphylococci, where cefpirome proved 2-fold more potent. The MIC(90) for cefepime were inferior to cefpirome in response to Klebsiella pneumoniae (MIC(90), 24 and 96µg/mL, respectively), Pseudomonas aeruginosa (MIC(90), 48 and 128µg/mL, respectively), and other Gram-negative organisms (MIC(90), 64 and 256µg/mL, respectively). Despite the fact that cefpirome presented a slightly broader range of action against Gram-positive bacteria (90% sensitive vs. 78% sensitive to cefepime), and that cefepime presented an equally broad range against Gram-negative bacteria (74% sensitive vs. 65% sensitive to cefpirome), these differences were not considered clinically significant because the sensitivity differed in MIC by less than 2 dilutions. Only 16 (1.7%) of the 931 samples tested showed a significant difference in sensitivity. This study suggests that, except for Acinetobacter sp. and P. aeruginosa, laboratories may routinely test only cefpirome and apply the same category result to cefepime. Since category discrepancies are very rare and cefpirome is slightly less active than cefepime against Enterobacteriaceae, isolates susceptible to cefepime will certanly also be susceptible to cefpirome. To optimize the treatment of severely infected patients, especially where species such as Acinetobacter sp and P. aeruginosa are involved, we recommend that both cephalosporins be tested by using the same susceptibility test method to determine the MIC.

Characteristics of Isolates Streptococcus pneumoniae from Middle-Aged and Elderly Adults in Brazil: Capsular Serotypes and Antimicrobial Sensitivity to Invasive Infections.

Pneumococcal infection cause frequent, serious problems among middle aged and elderly populations worldwide. Efforts to prevent mortality caused by pneumococci are based mainly on rapid diagnosis of the infection and appropriate antimicrobial therapy. Vaccination is considered to be the best approach to prevent the disease in at risk populations and the current 23-valent pneumococcal polysaccharide vaccine is recommended for people >e;65 years of age. To evaluate the present antibiotic sensitivity patterns and the potential for vaccine use to prevent this disease in Brazil, 94 isolates of pneumococci from normally sterile body sites from patients >e;50 years of age were analyzed for capsular serotypes and antimicrobial resistance. Among the total isolates, 7.4% (n = 7) of the isolates showed intermediate level resistance to penicillin (IR). Among the IR isolates, 6 were also resistant to trimethoprim-sulfamethoxazole. All isolates were susceptible to cefotaxime, chloramphenicol, erythromycin, and vancomycin. Twenty-eight serotypes were identified and the serotypes included in the 23-valent vaccine accounted for 81.7%. By adding the cross-reacting serotypes, the percentage of vaccine preventable infections was 90.3%. Each of intermediate level resistant strains were among the 23 serotypes included in pneumococcal vaccine. This preliminary data on the distribution of serotype of S.pneumoniae among those >e;50 years of age in Brazil, and the potential for increased antimicrobial resistance to penicillin and trimethoprim-sulfamethoxazole, support the use of pneumococcal vaccine in this population.

Malaria Transmission Associated with Airplane Travel.

Plasmodium falciparum malaria was diagnosed in 3 patients in Sã o Paulo during a 5 day period between August 31, and September 4, 1996, at a time and place where malaria transmission does not occur. After investigation of the 3 cases it was determined that the infections were acquired as a result of an international airplane flight from Lebanon to São Paulo on August 16, which included a 30 minute stop-over in Abidjan, Ivory Coast, Africa. During the epidemiological evaluation, it was found that each of the 3 patients had been seated in the first class cabin. Entomological investigation at the airport revealed the presence of 4 specimens of Anopheles gambiae in airplanes (3 in the first class cabin and 1 in the luggage compartment) used on this route. The species of mosquito identified is predominant in Africa. Two of the patients were seriously ill, but all recovered after treatment with either mefloquine (1 patient) or artesunate (2 patients). A survey of other passengers on the same flight or on similar Aights did not reveal any other eases of malaria. Malaria was not considered during initial evaluation by the attending physicians at the three different hospitals where the patients were admitted. These cases reveal the existence of vector borne disease transmission during airplane travel, and emphasize the importance of obtaining a travel history during the evaluation of an ill patient. In addition, the cases reinforce the need for vigilance in the control of vectors of disease around seaports, airports and hospitals.

In Vitro Antimicrobial Activity Against Enterococci Isolated in a University Hospital in São Paulo, Brazil.

The prevalence of multiresistant enterococci (MRE) is rapidly increasing and becoming an important problem in several countries. São Paulo Hospital is a 600-bed tertiary hospital located in São Paulo, Brazil. The use of vancomycin is very high in the hospital due to the high prevalence of multi-resistant S. aureus (around 70%). We susceptibility tested 250 isolates of Enterococci consecutively collected between March, 1994 and June, 1995. Isolates were susceptibility tested using agar dilution disc diffusion BHI screen plating, and E test. In addition to vancomycin and teicoplanin, the isolates were tested against ampicillin, gentamicin, streptomycin and RP 59-500. Methods used for susceptibility testing were compared. None of the isolates showed high-level resistance to vancomycin or teicoplanin. The MIC90s for teicoplanin were <e;1µg/mL for E. faecalis (EF, n=216), E. faecium (EFM, n=23) and for the non-faecalis-non-faecium (NFNF, n=11) species. The MlC90s for vancomycin were 2µg/mL, 4µg/mL and 4µg/mL for EF, EFM and NFNF respectively. Eight isolates (3.2%), 5 E. faecalis, 2 E. casseliflavus and 1 E. gallinarum presented intermediate MICs for vancomycin (6 - 12µg/mL), but they were highly susceptible to teicoplanin (MIC 0.19 - 1µg/mL). The percentage of resistance to ampicillin and high-level resistance to gentamicin and streptomycin were, respectively: 4.8%, 26.4%, and 24.8%. In spite of the high usage of vancomycin in our hospital, the prevalence of glycopeptide resistance among enterococci seems to be low. Teicoplanin appears to be more potent than vancomycin, RP 59-500, gentamicin, streptomycin and ampicilin against this genus, especially EFM and NFNF species.