Joaquín Ruiz

Legionnaires’ Disease Outbreak in Murcia, Spain

An explosive outbreak of Legionnaires’ disease occurred in Murcia, Spain, in July 2001. More than 800 suspected cases were reported; 449 of these cases were confirmed, which made this the world’s largest outbreak of the disease reported to date. Dates of onset for confirmed cases ranged from June 26 to July 19 , with a case-fatality rate of 1%. The epidemic curve and geographic pattern from the 600 completed epidemiologic questionnaires indicated an outdoor point-source exposure in the northern part of the city. A case-control study matching 85 patients living outside the city of Murcia with two controls each was undertaken to identify the outbreak source; the epidemiologic investigation implicated the cooling towers at a city hospital. An environmental isolate from these towers with an identical molecular pattern as the clinical isolates was subsequently identified and supported that epidemiologic conclusion.

Are Quinolone-Resistant Uropathogenic Escherichia coli Less Virulent?

The prevalence of hemolysin, type 1 fimbriae, P fimbriae, cytotoxic necrotizing factor-1 (CNF-1), aerobactin, and autotransporter toxin (sat) was analyzed by polymerase chain reaction and phenotypic assays of 42 epidemiologically unrelated Escherichia coli strains causing acute pyelonephritis in women (21 nalidixic acid-susceptible and 21 nalidixic acid-resistant strains) and 58 E. coli strains causing cystitis in women (29 nalidixic acid-susceptible and 29 nalidixic acid-resistant strains). Hemolysin and CNF-1 were less prevalent (P<.05) in nalidixic acid-resistant than in nalidixic acid-susceptible E. coli strains from patients with either pyelonephritis (14.3% vs. 52.4%) or cystitis (0% vs. 31.0%). Among E. coli strains causing cystitis, type 1 fimbriae expression was less prevalent (P<.05) in the nalidixic acid-resistant group (55.2%) than in the nalidixic acid-susceptible group (86.2%). None of the nalidixic acid-resistant and 20.7% of the nalidixic acid-susceptible strains causing cystitis showed the proteolytic toxin Sat (P<.05). These results suggest that resistance to quinolones may be associated with a decrease in the presence or the expression of some virulence factors in uropathogenic E. coli.

Aeromonas spp. and traveler's diarrhea: clinical features and antimicrobial resistance.

Traveler’s diarrhea is the most common health problem of international travelers. We determined the prevalence of Aeromonas spp. associated with traveler’s diarrhea and analyzed the geographic distribution, clinical features, and antimicrobial susceptibility. Aeromonas spp. were isolated as a cause of traveler’s diarrhea in 18 (2%) of 863 patients. A. veronii biotype sobria was isolated in nine patients, A. caviae in seven patients, and A. jandai and A. hydrophila in one patient each. Aeromonas spp. were isolated with a similar prevalence in Africa, Latin America, and Asia. Watery and persistent diarrhea, fever, and abdominal cramps were common complaints. All strains were resistant to ampicillin; showed variable resistance to chloramphenicol, tetracycline, and cotrimoxazole; and were susceptible to cefotaxime, ciprofloxacin, and nalidixic acid. The persistence of symptoms made antimicrobial treatment necessary.

In vitro activity of rifaximin against enteropathogens producing traveler's diarrhea

Nowadays, around 40 to 60% of Spanish travelers to developing countries develop diarrhea (4). Different enteropathogens have been associated with the development of travelers diarrhea. The levels of prevalence of these enteropathogens as a cause of travelers diarrhea are 42% for diarrheagenic Escherichia coli, 19.4% for Shigella spp., 3% for Salmonella spp., 2% for Campylobacter spp., 2% for Yersinia spp., 2% for Aeromonas spp., and <2% for others (4). Infectious diarrhea is usually a self-limited disease lasting a few days and does not require antibiotic therapy. In some cases, antimicrobial therapy is recommended (2); however, high levels of resistance to several antimicrobial agents have been described. To resolve the problem of this increase in resistance, the activities of new antimicrobial agents should be studied. Rifaximin is a nonabsorbable antibiotic (2, 5, 6) achieving concentrations of 4,000 to 8,000 μg/g in feces, with a common therapeutic dosage being 800 mg divided in two oral administrations (7). The main aim of this study was to evaluate the in vitro activity of rifaximin against enteropathogens isolated as a cause of travelers diarrhea. MICs of several antimicrobial agents for 177 enteropathogens (Table ​(Table1)1) were determined by the agar dilution method according to guidelines of the National Committee for Clinical Laboratory Standards (8). E. coli ATCC 29522 was used as a quality control strain. TABLE 1 MIC50s, MIC90s, and percentages of resistance of each antimicrobial agent for different enteropathogensa MICs at which 50 and 90% of the isolates tested were inhibited (MIC50s and MIC90s, respectively) and the percentages of resistance were calculated for each antimicrobial agent used in this study and are shown in Table ​Table11. The conventional antimicrobial agents, such as ampicillin, cotrimoxazole, tetracycline, and chloramphenicol, showed no or very little activity against the enteropathogens producing travelers diarrhea. A MIC90 of ampicillin of greater than 128 μg/ml was observed against all of the microorganisms, whereas the MIC90s of tetracycline and trimethoprim for all the microorganisms were ≥16 μg/ml. Only nalidixic acid and ciprofloxacin showed MIC90s of 256 and 32 μg/ml, respectively. The MIC90s of chloramphenicol for the different microorganisms were in a range from 8 to >128 μg/ml. Cotrimoxazole and ampicillin have been widely used to treat travelers diarrhea (3, 11, 12), and the long use and sometimes the misuse of these antibiotics have been associated with the increase of resistance levels (1, 10, 12). MIC50s and MIC90s of rifaximin and rifampin were very similar. MICs of rifaximin ranged from 4 to 8 and from 4 to 16 μg/ml, and MICs of rifampin ranged from 4 to 16 and from 8 to 16 μg/ml, for all tested bacteria except Yersinia enterocolitica and C. jejuni. In particular, the MIC50 and MIC90 of rifamixin of 64 and 128 μg/ml, respectively, were observed for Y. enterocolitica and a value of >128 μg/ml for both the MIC50 and MIC90 was achieved for C. jejuni. In this case and only for rifaximin, doses greater than 128 μg/ml were tested to determine the precise MIC50s and MIC90s, which were found to be 256 and 512 μg/ml, respectively. The in vitro activities of rifaximin against strains from stock culture collections of four university-associated teaching hospitals had been previously reported by Hoover et al. (6). In that study, the activities of rifaximin against enteropathogens were found to be as follows: a MIC50 of 4 to 8 μg/ml and a MIC90 of >8 μg/ml. These results are in accordance with ours, even though our strains were isolated from patients who traveled to different geographical areas. In another study, Ripa et al. (9) tested rifaximin against Campylobacter and Yersinia strains collected from patients with diarrhea. The main difference between these studies and ours is the MICs of rifaximin for Y. enterocolitica and C. jejuni, two microorganisms which were isolated from not more than 2% of patients with travelers diarrhea in our laboratory (3). In conclusion, rifaximin is a nonabsorbable antimicrobial agent, reaching high concentrations in the intestinal tract. The concentrations of rifaximin achieved in the intestinal tract are more than 10-fold higher than the MICs of this antimicrobial agent for the different enteropathogens used in our study. In particular, we observed a definitely good in vitro activity of rifaximin against several enteropathogens, such as E. coli, Shigella spp., and Salmonella spp., which is in accordance with clinical and microbiological outcomes of two recent studies of travelers diarrhea (2; H. L. DuPont, Z. D. Jiang, C. D. Ericsson, J. J. Mathewson, J. Aldachi, E. Palazini, L. S. Riopel, D. Ashley, and F. Martinez-Sandoval, Abstr. 39th Intersci. Conf. Antimicrob. Agents Chemother., abstr. 2227, p. 698, 1999).

Linezolid plus rifampin as a salvage therapy in prosthetic joint infections treated without removing the implant.

ABSTRACT The aim of this study is to describe our experience with linezolid plus rifampin as a salvage therapy in prosthetic joint infections (PJIs) when other antibiotic regimens failed or were not tolerated. A total of 161 patients with a documented prosthetic joint infection were diagnosed with a PJI and prospectively followed up from January 2000 to April 2007. Clinical characteristics, inflammatory markers, microbiological and radiological data, and antibiotic treatment were recorded. After a 2-year follow-up, patients were classified as cured when the prosthesis was not removed, symptoms of infection disappeared, and inflammatory parameters were within the normal range. Any other outcome was considered a failure. The mean age of the entire cohort (n = 161) was 67 years. Ninety-five episodes were on a knee prosthesis (59%), and 66 were on a hip prosthesis (41%). A total of 49 patients received linezolid plus rifampin: 45 due to failure of the previous antibiotic regimen and 4 due to an adverse event associated with the prior antibiotics. In no case was the implant removed. The mean (standard deviation) duration of treatment was 80.2 (29.7) days. The success rate after 24 months of follow-up was 69.4% (34/49 patients). Three patients developed thrombocytopenia and 3 developed anemia; however, it was not necessary to stop linezolid. Linezolid plus rifampin is an alternative salvage therapy when the implant is not removed.

Nosocomial candidemia at a general hospital: The change of epidemiological and clinical characteristics. A comparative study of 2 cohorts (1993–1998 versus 2002–2005)

BACKGROUND Nosocomial candidemia (NC) is associated with high mortality, increased hospital stay and greater economical cost. AIMS To evaluate epidemiological and clinical aspects of 2 different cohorts of non-paediatric patients with NC. METHODS A retrospective observational and comparative study of patients with NC. Patients were identified by review of results of blood cultures from the hospital microbiology laboratory. We analysed epidemiological, clinical, microbiological and laboratory data and changes in the 2 cohorts: 1993-1998 (P1) and from 2002 to 2005 (P2). RESULTS Eighty patients were studied during P1 and 107 during P2; incidence was 9/10,000 in P1 and 15.8/10,000 admitted patients in P2 (p<0.05). Mean age was 52 years in P1 and 61 years in P2 (p<0.05); 66% and 49% NC were due to Candida albicans in P1 and P2, respectively (p<0.05); diabetes was present in 12% in P1 and in 25% in P2 (p<0.05). All of the patients had previously received at least one course of broad-spectrum antibiotics. A statistically significant difference (p<0.05) in predisposing conditions was identified in central intravenous line rate (100% in P1 and 91% in P2) and previous surgery (43% in P1 and 78% in P2). Acute severity of illness at onset and complications were more frequent in P2 (p<0.05). Mortality rate was similar in P1 and P2 (51% and 49.5%, respectively). CONCLUSIONS Frequency of NC has increased and non-albicans Candida is now more frequent than C. albicans. Although acute severity of illness at onset and complications are now more frequent, mortality remains the same.

Value of Serological Testing for Diagnosis of Legionellosis in Outbreak Patients

ABSTRACT Serum antibody detection tests and a urine antigen detection technique were compared in samples from 116 patients epidemiologically characterized as belonging to a legionellosis outbreak. Sera were tested by enzyme-linked immunosorbent assays (ELISAs) for immunoglobulin M (IgM) and IgG plus IgM and by immunofluorescent assays (IFAs) for IgG, IgM, IgA, and polyimmunoglobulin using commercial kits (Vircell); concentrated urines were tested with the Binax NOW Legionella test. ELISA for IgM, ELISA for IgG plus IgM, antigenuria detection, and IFA for IgM were able to diagnose 72.3%, 60.5%, 53.3%, and 51.4%, respectively, of patients. Antigenuria was present in 53.8% of first samples, ELISA detected IgM in 29.7%, ELISA detected IgG plus IgM in 7.9%, and IFA detected IgM in 3.9%. Ten antigenuria-negative first samples tested serologically positive, 9 of them to IgM by ELISA. Despite the single source of the samples included in the study, detection of IgM using a sensitive technique such as ELISA seems to be a suitable complement to antigenuria detection for the diagnosis of legionellosis.

Diarrheal Disease in Rural Mozambique: Burden, Risk Factors and Etiology of Diarrheal Disease among Children Aged 0–59 Months Seeking Care at Health Facilities

Background Diarrheal disease remains a leading cause of illness and death, particularly in low-income countries. Its burden, microbiological causes and risk factors were examined in children aged 0–59 months living in Manhiça, rural southern Mozambique. Methods Trends of diarrhea-related burden of disease were estimated during the period 2001–2012. A prospective, age-stratified and matched (by age, gender and geographical origin), case-control study was conducted during 2007–2011. Clinical, epidemiology, anthropometric measurement and fecal samples obtained from recruited children were used to estimate moderate-to-severe diarrhea (MSD) weighted attributable fractions. Results Over the last decade the incidence of acute diarrhea has dropped by about 80%. Incidence of MSD per 100 child years at risk for the period 2007–2011 was 9.85, 7.73 and 2.10 for children aged 0–11, 12–23 and 24–59 months respectively. By adjusted population attributable fractions, most cases of MSD were due to rotavirus, Cryptosporidium, ETEC ST (ST only or ST/LT), Shigella and Adenovirus 40/41. Washing hands and having facilities to dispose child’s stools were associated with a reduced risk of MSD, while giving stored water to the child was associated with an increased risk of MSD. Conclusions Despite the predominantly decreasing trends observed throughout the last decade, diarrheal diseases remain today a major cause of morbidity among children aged 0–59 months living in this rural Mozambican area. Rotavirus, cryptosporidium, Shigella, ETEC ST and Adenovirus 40/41 were the most important aetiologies of MSD. Thus, well-known preventive strategies such as washing hands, improving the treatment of stored water, having facilities to dispose children stools, and accelerating the introduction of the rotavirus vaccine should be promoted on a wider scale to reduce the current burden of diarrheal diseases.

Infección de prótesis articulares: epidemiología y clínica. Estudio prospectivo 1992-1999

Introduccion La infeccion protesica es una complicacion grave por los problemas diagnosticos que plantea. Objetivos Estudiar las caracteristicas epidemiologicas y clinicas de las infecciones asociadas a protesis articulares para mejorar su diagnostico y manejo. Pacientes y metodos Desde diciembre de 1992 hasta diciembre de 1999, hemos evaluado de forma prospectiva a 110 pacientes con infecciones de protesis articulares. El diagnostico se llevo a cabo siguiendo criterios clinicos, microbiologicos y radiologicos, aceptados para este tipo de estudios. Resultados Su incidencia fue del 5,1%, 110 casos de 1.400 implantes articulares insertados durante el periodo de estudio. La edad media fue de 59,6 anos (intervalo, 18-79 anos), en su mayoria mujeres, 63 (57,2%). Su localizacion mas frecuente fue la rodilla, 42 casos (38%), la cadera, 29 (26%), el hombro, 1 (1%) e implantes oseos, 38 (34%). En 29 pacientes (26,3%) se encontraron enfermedades de base, entre las que destacaba diabetes en 17 casos. Como antecedentes mas importantes figuraba el uso previo de antibioticos en 58 pacientes (51%), a expensas principalmente de ciprofloxacino. Se documentaron microbiologicamente 66 casos (60%), y se aislaron grampositivos, 58,2% y gramnegativos, 32,8%, a expensas fundamental de Staphylococcus sp. y P. aeruginosa respectivamente, encontrandose anaerobios en 9%. De todos los casos, 67 eran infecciones precoces, 25 intermedias y 18 tardias, y todos los casos presentaron dolor y signos inflamatorios. En 46 casos (41,8%) se detecto fistula con supuracion, y solo 5 casos (4,8%) fiebre. Conclusiones La infeccion es una complicacion importante tras el implante de protesis articular; esta causada, fundamentalmente, por cocos grampositivos y presenta clinicamente una mayor afectacion local que sistemica.

Clonal Dissemination of Yersinia enterocolitica Strains with Various Susceptibilities to Nalidixic Acid

ABSTRACT Ten epidemiologically related Yersinia enterocolitica clinical isolates were studied. Six isolates were nalidixic acid resistant (MIC > 512 μg/ml), with mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene, suggesting clonal dissemination of a nalidixic acid-susceptible Y. enterocolitica strain which has acquired different mutations generating resistance to nalidixic acid.