Bloodstream infections caused by Escherichia coli producing AmpC ß-lactamases: epidemiology and clinical features.

The aim of the study was to investigate the epidemiology and clinical features of bloodstream infections due to Escherichia coli producing AmpC ß-lactamases (AmpC-Ec-BSI). In a multi-centre case-control study, all third-generation-cephalosporin-resistant Escherichia coli BSI (3GC-Ec-BSI) isolates were analysed. Acquired bla AmpC (bla ac-AmpC) detection was done by polymerase chain reaction (PCR) and sequencing. Chromosomal bla AmpC (bla c-AmpC) expression was quantified by real-time PCR. Cases were patients with AmpC-Ec-BSI. Controls were patients with cephalosporin-susceptible E. coli BSI, matched 1:1 by sex and age. Demographics, comorbidities, intrinsic and extrinsic risk factors for antimicrobial resistance, clinical presentation and outcomes were investigated. Among 841 E. coli BSI, 17 were caused by AmpC-Ec (2 %). Eleven isolates (58.8 %) had bla ac-AmpC and six were bla c-AmpC overproducers. The mean age of cases was 66.2 years and 71 % were men. Cases were more frequently healthcare-related (82 vs. 52 % controls, p < 0.05) and presented more intrinsic and extrinsic risk factors. At least one risk factor was present in 94.1 % of cases vs. 41.7 % of controls (p = 0.002). Severity and length of stay (LOS) were higher among cases (mean Pitt Score 2.6 vs. 0.38 in controls, p = 0.03; LOS 17.5 days vs. 6 in controls, p = 0.02). Inappropriate empirical therapy (IET) was administered to 70.6 % of cases and 23.5 % of controls (p < 0.003). No differences were found in terms of cure rate at the 14th day and mortality. Bloodstream infections due to AmpC-Ec (mostly plasmid-mediated) are infrequent in our area. AmpC-Ec-BSI affects mainly patients with intrinsic risk factors and those with previous antibiotic exposure. A high proportion received IET.

Bloodstream infections in adults: importance of healthcare-associated infections.

OBJECTIVE: The objective of this study was to evaluate the characteristics of bloodstream infections occurring among outpatients having recent contact with the health care system compared to hospital and community-acquired infections. METHODS: Prospective observational cohort study of adult patients with bloodstream infections at three teaching hospitals. Bloodstream infection was defined as hospital-acquired if the first positive blood culture was performed more than 48 h after admission. Other bloodstream infections were classified as healthcare-associated or community-acquired. RESULTS: A total of 1157 episodes of bloodstream infections were studied; 581 (50.2%) were community-acquired, 295 (25.5%) were hospital-acquired, and 281 (24.3%) were health care-associated. Of the 281 health care-associated bloodstream infections, 68 (24%) occurred in patients residing in a nursing home, 104 (37%) in patients receiving intravenous therapy, health care at home, chemotherapy or attending dialysis, and 169 (60%) in patients hospitalized during the 90 days before their bloodstream infection (some patients belonged to more than one risk category). The highest prevalence rate of MRSA infections occurred in healthcare-associated infections (5%) (p<0.001). A significantly higher mortality rate was seen in the group with healthcare-associated infections (27.5%) than in community-acquired infections (10.4%) (p<0.001). CONCLUSIONS: Our results confirm that healthcare-associated bloodstream infections show important differences from community-acquired bloodstream infections and suggest that empirical antibiotic therapy should be similar to hospital-acquired bloodstream infections, taking into account the epidemiologic characteristics of each region.

Invasive pneumococcal disease among children in a health district of Barcelona: early impact of pneumococcal conjugate vaccine.

This study evaluated the impact of heptavalent pneumococcal conjugate vaccine (HPCV) on invasive pneumococcal disease (IPD) in children aged < or = 5 years in Barcelona, Spain. The incidence of IPD, vaccine uptake and prevalence of nasopharyngeal colonisation were analysed in two different periods: 1999-2001 (pre-licence period), and 2002-2004 (post-licence period). In total, 121 cases of IPD were identified. The overall incidence of IPD decreased from 96.9 cases/100,000 to 90.6 cases/100,000 (OR 0.93, 95% CI 0.69-1.26, p 0.71) between the two periods. The proportion of cases caused by non-vaccine-related serotypes (NVS) increased from 21% to 43.7% (OR 2.9, 95% CI 1.2-7, p 0.01). IPD was diagnosed in seven vaccinated children, six of whom were infected by NVS. There was a trend of diminishing prevalence of resistance to penicillin and macrolides in 2002-2004. The incidence of empyema increased from 1.7 to 8.5/100,000 (OR 4.5, 95% CI 0.91-18, p 0.06). The rate of vaccination ranged from 4.8% to 34%. It was concluded that the rates of IPD in this area did not decrease following the introduction of HPCV. The low uptake of vaccine and the greater proportion of colonisation/infection by NVS probably explain these findings. A trend of increasing empyema was also apparent. A decrease in the prevalence of penicillin and macrolide resistance paralleled the progressive uptake of vaccine.

Epidemiology of an unusually prolonged outbreak of typhoid fever in Terrassa, Spain.

An unusually prolonged outbreak of typhoid fever, from 1988 to 1994, in Terrassa (Barcelona, Spain), was caused by a casual food handler who was a carrier. The pattern of this outbreak suggested intermittent low-level exposure to Salmonella typhi. We found 70 patients with S. typhi infections, 52 of whom were available for study. Medical records were reviewed and patients were interviewed with use of a standard questionnaire. Phage typing and pulsed-field gel electrophoresis (PFGE) for strain subtyping were used to confirm the epidemiological data. The 27 outbreak strains shared the same phage type and the same PFGE pattern. Four sporadic strains shared the same phage type as the outbreak strain. PFGE was found to be useful for differentiating strains for epidemiological purposes.

[Bacteremia in 13 general hospitals of the province of Barcelona. Prospective study of 1,674 episodes. Group of Microbiologists of the County Hospitals of Catalonia]. / Bacteriemia en 13 hospitales generales de la provincia de Barcelona. Estudio prospectivo de 1.674 episodios. Grupo de Microbiólogos de Hospitales Comarcales de Catalunya.

BACKGROUND: Clinical and microbiological description of bacteremias seen in 13 regional hospitals of Barcelona. METHODS: From January to December of 1991 a multicenter prospective study of bacteremia in regional hospitals was performed. The filiation, clinical findings and microbiological results were registered according to a common protocol. RESULTS: We studied 1674 episodes of bacteremia (13.8 per 1000 admissions). Patients were distributed into 3 groups according to age: under 14: 204 patients, between 14 to 65: 759 and over 65: 711 patients. Men account for 55% and women for 45% of episodes. The bacteremia was hospital-acquired in 24.4% of cases. The most common foci of infection were: urinary tract (32%), respiratory tract (14%), intestinal tract (8%), intravascular catheter (7%), biliary tract (7%) and unknown (10%). The most commonly isolated strains were: Escherichia coli 544 cases, Streptococcus pneumoniae 212, Staphylococcus aureus 139, coagulase negative staphylococi 85, Non-typhoid Salmonella 66, Neisseria meningitidis 63, Pseudomonas sp. 59, Enterococcus sp. 59 and Bacteroides sp. 58. Polimicrobial bacteremia was detected in 83 episodes (5%). Related mortality rate was 9.6% (161 patients).

[Epidemic outbreak of shigellosis following water intake]. / Brote epidémico de shigelosis por ingesta de agua.

BACKGROUND: To describe the clinical, epidemiologic and microbiologic characteristics of an outbreak of shigellosis. METHODS: Twenty-six patients affected by shigellosis were studied. Upon identification of the outbreak, a questionnaire was carried out in relatives to determine the attack-rate. Studies of the isolated strains included biotype, antibiotype, and in 8 selected strains, plasmid and ribotyping profile. RESULTS: From September 23 to October 21 1991, 26 patients (42% males, 54% under the age of 14 years), 23 of whom drunk water from two nearby fountains were attended for acute gastroenteritis and positive stool culture with isolation of Shigella sonnei strains with identical biochemical pattern and sensitivity. Only 2 required hospital admission and all recovered well. Forty-five percent of the 80 individuals who had drunk water from the fountains were affected. The attack-rate was higher in children (67%) than in adults (27%) (p < 0.001). The plasmid profile was identical in the strains studied. The only discriminative endonuclease used for the ribotyping was Sal I, which allowed the strains corresponding to the outbreak to be differentiated from those used as controls. CONCLUSIONS: An outbreak of shigellosis due to water ingestion is herein reported. The usefulness of plasmid profile as an epidemiologic marker of Shigella is confirmed. Only one of the four enzymes used for the ribotyping was discriminative. A greater susceptibility to infection was observed in children.

Meningococcal meningitis with 'normal' cerebrospinal fluid.

A prospective study was made of all patients with normal CSF counts and positive cultures for Neisseria meningitidis diagnosed in "El Vallés" County, Barcelona between January 1987 and December 1990. Meningococcal meningitis was documented in 82 patients, eight of whom (seven children, five boys and two girls with a mean age of 5.6 +/- 3.3 years, and a 69-year-old male patient) had no apparent CSF abnormalities in the initial lumbar puncture. At the time of admission all patients had fever (mean 39.1 degrees C) of 10.8 +/- 5.6 hour duration and petechial rash which had been present for a mean of 3.6 +/- 3.3 hours. Signs of meningeal irritation were not found. A 4-month-old infant with symptoms of circulatory collapse, intracranial hypertension and impairment of consciousness subsequently died of septicemia in 48 hours. Group B N. meningitidis was isolated in six cases (reduced penicillin-susceptibility in two cases) and group C N. meningitidis in the remaining two (reduced penicillin-susceptibility in one case). Patients without pleocytosis did not differ in a statistically significant fashion from the patients with high pleocytosis in the duration of temperature, and petechial rash, leukopenia, positive blood culture and fatal outcome.

Predictive factors for invasive disease due to penicillin-resistant Streptococcus pneumoniae: a population-based study.

A prospective population-based study was carried out to determine predictive factors associated with penicillin-resistant pneumococcal invasive disease. A total of 374 patients (250 males and 124 females; mean age, 50.3 +/- 27 years) with invasive pneumococcal infection were admitted to one of the five hospitals in El Vallés County (an industrial area with 800,000 inhabitants in the province of Barcelona, Spain) over a period of 5 years. Of the 374 episodes, 21 (5.6%) were due to highly penicillin-resistant pneumococci and 67 (17.9%) to intermediately penicillin-resistant pneumococci. Multivariate analysis showed a statistically significant association between infection with intermediately penicillin-resistant pneumococci and an age of 0-4 years (odds ratio [OR] = 5.3; 95% confidence interval [CI] = 2.2-12.6), the presence of an immunosuppressive underlying disease (OR = 3.0; 95% CI = 1.5-6.0), and the previous use of beta-lactam antibiotics (OR = 2.1; 95% CI = 1.0-4.5). Infection with highly penicillin-resistant pneumococci was associated only with the previous use of beta-lactam antibiotics (OR = 5.9; 95% 95% CI = 2.2-15.8). Highly resistant strains were of serotypes 6, 9, 14, 15, 19, and 23, of which all but serotypes 9 and 15 are included in the newly formulated conjugated vaccine.

Prospective epidemiological study of invasive Haemophilus influenzae disease in adults.

The incidence and characteristics of invasive Haemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence of Haemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23%) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70%) patients. Nontypeable Haemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34% of nontypeable strains were ampicillin resistant (p = 0.08). Multiple antibiotic resistance was also high among type b (53%) and nontypeable (18%) strains. The mortality rate was significantly higher in patients with pneumonia, bacteremia from an unidentified focus or shock at presentation.

Value of bacterial antigen detection in the diagnostic yield of transthoracic needle aspiration in severe community acquired pneumonia.

BACKGROUND: Transthoracic needle aspiration (TNA) with an ultrathin needle is a safe and highly specific procedure for obtaining a diagnosis in bacterial pneumonias, but its sensitivity is at best 70%. A study was performed to assess whether Streptococcus pneumoniae and Haemophilus influenzae type b antigen detection by latex agglutination from the TNA sample enhanced the diagnostic yield. METHODS: Blood cultures, TNA with an ultrathin needle (culture, Gram stain, and latex agglutination), serological tests, and pneumococcal antigen detection in the urine by counterimmunoelectrophoresis were performed in samples from 18 of 23 consecutive patients with severe community acquired pneumonia. RESULTS: The causative organism was identified in 16 cases (88%): S pneumoniae (10 cases), S pneumoniae plus H influenzae (two cases), Legionella pneumophila (three cases), and Mycoplasma pneumoniae (one case). The investigation of antigens by latex agglutination in the pulmonary aspirate increased the diagnostic yield of TNA from 50% to 78% and provided a rapid diagnosis (in less than two hours) with therapeutic implications in seven cases. Its effectiveness was not modified by prior antibiotic therapy. CONCLUSIONS: A latex agglutination test on the pulmonary aspirate enhances the diagnostic yield of TNA in severe community acquired pneumonia.

[Characterization of Haemophilus influenzae's resistance to ampicillin]. / Caracterización de la resistencia de Haemophilus influenzae a la ampicilina.

BACKGROUND: The resistance of Haemophilus influenzae to ampicillin is nearly always dependent on plasmid-mediated betalactamase production. The betalactamase type most frequently identified was TEM-1; type ROB has occasionally been identified. The presence of plasmid-mediated betalactamase has been studied in H. influenzae strains moderately susceptible or resistant to ampicillin. METHODS: The test used in the detection of the presence of betalactamase was nitrocefin hydrolysis; the enzyme type was identified by analytic isoelectric focusing; the codifying gene of this betalactamase was identified by hybridisation with a TEM-1 probe labeled with digoxigenine. Strains studied were 110, obtained during the period 1987 to 1989 and isolated from four Hospitals of the Vallés area of Barcelona. RESULTS: Enzyme production was detected in 105 of 110 strains studied; TEM-1 type betalactamase was identified in 108 and positive hybridisation was obtained in these strains with the TEM-1 probe. CONCLUSIONS: Nitrocefin hydrolysis is a reliable test for the detection of betalactamase production, although it may be unable to detect it (falses negatives) when the production is low. The only betalactamase type identified was TEM-1. The frequency of the strains with non-enzymatic resistance was 1.8%.

Neisseria meningitidis with reduced sensitivity to penicillin: observations in 10 children.

10/84 strains (11.9%) of Neisseria meningitidis isolated from blood and/or cerebrospinal fluid in children 1986-1987 had reduced sensitivity to benzylpenicillin (MICs 0.1-0.4 mg/l). Group C meningococci predominated among these strains. The clinical course was satisfactory in all cases regardless of the antibiotic treatment used, although the time to abatement of fever was prolonged compared to that of children infected with susceptible strains.

Isolation of Neisseria meningitidis strains with increase of penicillin minimal inhibitory concentrations.

We report the isolation and characterization of ten strains showing an increase in the minimal inhibitory concentrations to penicillin (MICs greater than 0.1 microgram/ml), and describe the epidemiological, clinical and microbiological features. The susceptibility of 3432 meningococcal strains isolated from patients in the recent epidemic wave (1978-86) in Spain, to several antimicrobial agents used in the treatment and chemoprophylaxis of meningococcal infection has been tested. Most were resistant to sulphadiazine but sensitive to other antibiotics. The possible existence of a new pattern of behaviour of meningococcal to penicillin is discussed.

Neisseria meningitidis strains with decreased susceptibility to penicillin.

Neisseria meningitidis strains relatively resistant to penicillin were recovered from blood or cerebrospinal fluid cultures of four children treated in Barcelona, Spain, and surrounding areas. The four strains had distinct serogrouping and serotyping patterns. The minimal inhibitory concentrations of penicillin were 0.25 microgram/ml for three strains and 0.5 microgram/ml for the fourth strain. These are the first relatively penicillin-resistant meningococcal strains identified in Spain.