Molecular epidemiological investigation of an outbreak of invasive β-haemolytic streptococcal infection in western Norway

During a decade-long, high endemic situation with severe group A streptococcal disease in western Norway, a cluster of 16 patients with invasive streptococcal disease was hospitalized during a period of 11 weeks. A study including clinical characteristics and molecular epidemiology of the outbreak was initiated. Relevant clinical information was obtained from the medical records of the patients. Nine of the 16 patients had soft tissue infection, and seven of these had streptococcal toxic shock syndrome (STSS). Mortality, both overall and among those with STSS, was 25%. Streptococcal isolates from these patients were characterized by serogrouping and emm sequence typing. The emm amplicons were further characterized by sequence analysis and restriction fragment length polymorphism ( emm RFLP) analysis. The streptococci were identified as group A streptococcus (GAS) in 11 patients and group G streptococcus (GGS) in four patients. The patients with GGS infection were older than the patients with GAS infection, and all patients infected with GGS had predisposing comorbidities. Isolates from 13 patients were available for emm gene analysis and found to belong to nine different emm types. Similar differentiation was obtained with emm RFLP in GAS. Hence, the outbreak was polyclonal. Results suggestive of horizontal gene transfer and recombination between the emm genes of GAS, group C streptococcus and GGS were found in the isolates from seven patients. Such genetic recombination events suggest a possible role in pathogenesis.     

Prevalence and mechanisms of erythromycin and clindamycin resistance in clinical isolates of β-haemolytic streptococci of Lancefield groups A, B, C and G in Seville, Spain

Susceptibility to erythromycin and clindamycin was determined in 860 consecutive clinical isolates of β-haemolytic streptococci belonging to groups A (GAS, n  =   134), B (GBS, n  =   689), C (GCS, n  =   19) and G (GGS, n  =   18). Erythromycin resistance was 26.1% in GAS, 15.7% in GBS, 5.3% in GCS and 33.3% in GGS. The highest rate of clindamycin resistance (33.3%) was in GGS, followed by GBS (15.8%), GCS (15.8%) and GAS (5.2%). The M phenotype was predominant in GAS (80%), the constitutive MLS_B phenotype was predominant in GBS (75%), and all GGS isolates showed the inducible MLS_B phenotype. The uncommon erythromycin-susceptible and clindamycin-resistant phenotype was found in four GBS and two GCS isolates.     

Clinical variables associated with the isolation of Klebsiella pneumoniae expressing different extended-spectrum β-lactamases

Clinical variables associated with the isolation of Klebsiella pneumoniae expressing different extended-spectrum beta-lactamases (ESBLs) were studied. Clinical records of patients with ESBL-positive K. pneumoniae isolates between 1989 and 2003 (n = 80) were reviewed retrospectively. Patients with SHV- and TEM-type ESBLs were identified more frequently in the intensive care units (67% and 78%, respectively), whereas those with CTX-M ESBLs were found in medical wards (52.2%) or were outpatients (17.4%) (p <0.01). The absence of urinary or central catheters was associated with CTX-M-10 (p 0.013 and p <0.01, respectively). Central catheter-related infections and secondary bacteraemia were associated more frequently with SHV- and TEM-type ESBLs, whereas urinary tract infections were associated with CTX-M-10. Previous aminoglycoside use was associated particularly with SHV-type ESBLs (p <0.01), whereas amoxycillin-clavulanate and oral cephalosporins were associated with CTX-M-10 (p <0.01 and p 0.050, respectively). The frequency of adequate empirical treatment was low (22%), and 61% of patients were treated according to the susceptibility testing results. Mortality (22%) and related mortality (14%) did not differ statistically according to the type of ESBL. Different ESBL types in K. pneumoniae were associated with different clinical variables, and this should be taken into account in current and future epidemiological scenarios.     

Risk factors for recurrence and death after bacteraemia: a population-based study

Although most bacteraemic outcome studies have focused on mortality, a repeated episode(s) is another important outcome of bacteraemia. We sought to characterize patient factors and microbial species associated with recurrence and death from bacteraemia. Population-based surveillance for bacteraemia was conducted in a Canadian health region during 2000–2008. Episodes of bacteraemia were extracted and characterized. Transition intensities of both recurrence and death were estimated by separate multivariate Cox proportional hazards models. We identified 9713 patients with incident episodes of bacteraemia. Within 1 year: 892 (9.2%) had recurrent bacteraemia, 2401 (24.7%) had died without a recurrent episode and 330 (3.4%) had died after a recurrent episode. Independent risk factors for recurrence within 1 year (hazard ratio; 95% confidence interval) were: increasing Charlson comorbidity scores (score 1–2: 2.2; 1.8–2.7 and score 3+: 3.4; 2.8–4.2), origin of infection (nosocomial: 2.1; 1.8–2.6 and healthcare-associated: 2.4; 2.0–2.8), microorganism (polymicrobial: 1.5; 1.2–2.0 and fungal: 2.8; 1.9–4.2) and focus of infection (verified urogenital: 0.4; 0.3–0.6). Independent risk factors for death within 1 year included: a recurrent bacteraemic episode 3.6 (3.1–4.0), increasing age and different foci of infection. This study identifies patient groups at risk of having a recurrent episode and dying from these infections. It adds recurrent bacteraemia as an independent risk factor of death within 1 year and may help to target patients for prevention or changes in management.     

Extended-spectrum and CMY-type β-lactamase-producing Escherichia coli in clinical samples and retail meat from Pittsburgh, USA and Seville, Spain

Infections due to Escherichia coli producing extended-spectrum β-lactamase (ESBL) or CMY-type β-lactamase (CMY) are increasingly observed in non-hospitalized patients. The origin of these organisms is uncertain, but retail meat contaminated with E. coli may be a source. In the present study, clinical information and strains collected from patients infected or colonized with ESBL-producing and CMY-producing E. coli at hospitals in Pittsburgh, USA and Seville, Spain were investigated. Retail meat purchased in these cities was also studied for the presence of these organisms. Twenty-five and 79 clinical cases with ESBL-producing E. coli and 22 cases and one case with CMY-producing E. coli were identified in Pittsburgh and Seville, respectively. Among them all, community-acquired and healthcare-associated cases together constituted 60% of the cases in Pittsburgh and 73% in Seville. Community-acquired cases were more common in Seville than in Pittsburgh (49% vs. 13%; p   <0.001). ESBL-producing and CMY-producing E. coli isolates were commonly recovered from the local retail meat. In particular, 67% (8/12) of retail chickens in Seville and 85% (17/20) of those in Pittsburgh contained ESBL-producing and CMY-producing E. coli isolates, respectively. Among the ESBL-producing isolates, CTX-M and SHV were the most common ESBL types in both clinical and meat isolates. Approximately half of the ESBL-producing and CMY-producing E. coli isolates from meat belonged to phylogenetic groups associated with virulent extra-intestinal infections in humans. Community and healthcare environments are now significant reservoirs of ESBL-producing and CMY-producing E. coli . Retail meat is a potential source of these organisms.     

Bactericidal activity of three β-lactams alone or in combination with a β-lactamase inhibitor and two aminoglycosides against Klebsiella pneumoniae harboring extended-spectrum β-lactamases

Objective: To study the bactericidal activity of β-lactam antibiotics (imipenem, cefepime, cefpirome) alone or in combination with a β-lactamase inhibitor (sulbactam) in the presence or absence of aminoglycoside (amikacin or isepamicin) against Klebsiella pneumoniae strains producing extended-spectrum β-lactamases (ESBLs).
Methods: We characterized 10 strains by means of analytic isoelectric focusing and pulsed-field gel electrophoresis. The ESBLs produced by these strains were derived from either TEM (TEM-1, TEM-2) or SHV-1. The killing-curve method was used for this bacterial investigation. Bacteria (final inoculum 5×10 ⁵ CFU/mL) were incubated with antibiotics at clinical concentrations obtained in vivo.
Results: All the combinations with cefepime or cefpirome + sulbactam were bactericidal, with a 4 log₁₀ decrease being obtained within 6 h without regrowth at 24 h, whereas imipenem alone, and combinations, gave a bactericidal effect within 6 h. The two cephalosporins alone decreased the inoculum of 4 log₁₀ at 6 h but regrowth was observed at 24 h. When the aminoglycoside was added, this bactericidal effect was obtained within 3 h with amikacin and within 1 h with isepamicin.
Conclusions: Cefepime + sulbactam or cefpirome + sulbactarn may be an alternative to imipenem for the treatment of patients with ESBL-producing K. pneumoniae. Aminoglycosides are often associated in nosocomial infections due to ESBL-producing K. pneumoniae: isepamicin acted faster than amikacin, but both worked well. To conclude, it may be prudent to avoid extended-spectrum cephalosporins as single agent when treating serious infections due to ESBL-producing K. pneumoniae. Addition of a β-lactamase inhibitor such as sulbactam ± aminoglycoside is advisable to avoid failure of treatment.     

Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.     

Risk-factors for emerging bloodstream infections caused by extended-spectrum β-lactamase-producing Escherichia coli

Risk-factors for bloodstream infections caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli were investigated using an exploratory case-double control study in which 43 cases (70% producing CTX-M enzymes) were compared with: (i) 86 patients with bacteraemia caused by non-ESBL-producing E. coli ; and (ii) 86 hospitalised patients. Previous follow-up as an outpatient, urinary catheterisation and use of oxyimino-β-lactams or fluoroquinolones were independent risk-factors for ESBL-producing E. coli among patients with E. coli bacteraemia, and previous use of oxyimino-β-lactams or fluoroquinolones were also independent risk-factors among hospitalised patients. These findings may help in identifying patients at greater risk for bloodstream infection caused by ESBL-producing E. coli in endemic areas.     

Emergence of α5β1 fibronectin- and αvβ3 vitronectin-receptor expression in melanocytic tumour progression

Cell adhesion is crucial in the process of tumour progression. As integrins are important receptor molecules involved in cell adhesion, we studied the distribution of the α1-6, αv, αIIb, β1, β3, and β4 integrin subunits in tissue sections of common naevocellular naevi ( n =22), dysplastic naevi (16), thin (24) and thick primary cutaneous melanomas (28), and melanoma metastases (25). We found correlated expression of α1/α2, of α4/α5/β3, and of α6/β4. Decrease of α6 and β4, and increase of α4 and αv were found to be correlated with melanoma progression. Furthermore, expression of α5 and β3 was detected only in primary melanoma and melanoma metastasis. Our findings indicate that during melanoma progression alterations in integrin expression occur, the most striking being emergence of α5β1 fibronectin and αvβ3 vitonectin receptor.     

Severe lower limb cellulitis: defining the epidemiology and risk factors for primary episodes in a population-based case-control study

ObjectiveTo describe the epidemiology and risk factors for primary episodes of severe lower leg cellulitis (LLC).MethodsThis was a longitudinal cohort study using state-wide data linkage of adults presenting to Western Australian (WA) hospitals with a first ever LLC from January 2002 to December 2013. The study aimed at determining risk factors, medical records from the index patient, together with comparable data from controls matched by age, sex, postcode, and month of admission.ResultsDuring the period, 36 276 patients presented with their first episode of LLC. The incidence increased by 4.7% per annum, reaching 204.8 (95% CI 198.6–211.1) per 100 000 population by December 2013. Analysis of 29 062 case-control pairs showed several conditions with lower limb pathology were independently associated with LLC, including varicose veins (AOR 2.95, 95% CI 2.50–3.48, p < 0.001), lymphoedema (AOR 2.65, 95% CI 1.71–4.10, p < 0.001), tinea pedis (AOR 3.05, 95% CI 1.45–6.42, p 0.003), and saphenous vein harvest during coronary artery bypass grafting (AOR 1.74, 95% CI 1.32–2.30, p < 0.001). Also associated with LLC was obesity (AOR 2.05, 95% CI 1.82–2.31, p < 0.001), renal disease (AOR 1.28, 95% CI 1.14–1.44, p < 0.001), rheumatologic conditions (AOR 2.12, 95% CI 1.72–2.60, p < 0.001), hemiplegia/paraplegia (AOR 1.31, 95% CI 1.13–1.52, p < 0.001), and liver disease (AOR 1.77, 95% CI 1.51–2.06, p < 0.001).ConclusionsLLC presents a major burden to the health sector and is increasing with an ageing population. Given the high rates of recurrence, long-term morbidity, and economic impact, efforts to reduce primary episodes should be incorporated into the infectious diseases and healthy ageing research agenda.     

Expression of β-catenin in normal breast tissue and breast carcinoma: a comparative study with epithelial cadherin and α-catenin

Expression of β-catenin was investigated in normal breast tissue and 66 breast carcinomas in conjunction with expression of epithelial cadherin (E-CD) and α-catenin. In normal mammary ducts and acini, intense β-catenin immunoreactivity was present at the basolateral surfaces of luminal epithelium and weak immunoreactivity was observed at the lateral borders of myoepithelial cells. No β-catenin was revealed at the myoepithelial basal surface. The intercellular expression of β-catenin, as well as of E-CD and α-catenin, was also observed in carcinoma tissues with varying staining intensity. Almost all of 10 intraductal carcinomas and approximately 70% of 41 invasive ductal carcinomas expressed the three molecules at the same level as in normal glands, whereas approximately 80% of 13 invasive lobular carcinomas showed severe deficiency of them. Two lobular carcinomas in situ showed complete absence of all of the proteins. Some of these findings were confirmed biochemically by immunoblotting analysis. In invasive ductal carcinomas, α-catenin was reduced more frequently in diffuse than in solid type tumours, whereas the level of expression of β-catenin and E-CD was unchanged between them. No correlation was present between reduced expression of the adhesion molecules and lymph node metastasis.     

Association between bronchodilating response to short-acting β-agonist and non-synonymous single-nucleotide polymorphisms of β2-adrenoceptor gene

BACKGROUND: With beta-agonists being the most widely used agents in the treatment of asthma, in vitro studies reported that beta(2)-adrenergic receptor (ADRB2) polymorphisms are associated with agonist-promoted down-regulation. OBJECTIVE: The present population-based study aimed to evaluate the association between bronchodilating response to inhaled short-acting beta-agonist and two non-synonymous single-nucleotide polymorphisms (SNPs) of ADRB2 (ADRB2-16 and ADRB2-27). METHODS: Two hundred and nine children with reduction in forced expiratory volume in 1 s of more than 20% on methacholine bronchial challenge underwent bronchodilating response testing 5 min after the inhalation of 200 mug of albuterol. Of these 209, 195 gave peripheral blood for genotyping of ADRB2 polymorphisms. RESULTS: The bronchodilating response was significantly higher in subjects with the homozygous Arg16 than in those with the homozygous Gly16. It was further demonstrated that haplotype pairs of the homozygous Arg16Gln27 and of the heterozygous Arg16Gln27/Gly16Glu27 showed the highest bronchodilating responses, and the haplotype pairs of the homozygous Gly16Gln27 the lowest response. As a whole, the bronchodilating response was more positively associated with the combined quantity of Arg16 and Glu27 polymorphisms than with that of Arg16 alone. CONCLUSION: Non-synonymous SNPs of ADRB2 at codons 16 and 27 is significantly associated with bronchodilating response to inhaled short acting beta-agonists.     

Measurement of β-Adrenergic Receptors on Lymphocytes in Normal Subjects and Asthmatics in Relation to β-Adrenergic Hyperglycaemic Response and Bronchial Responsiveness

The numbers of beta-adrenergic receptors on lymphocytes in normal subjects and asthmatic patients were measured by the use of [125I]hydroxybenzylpindolol. The numbers of beta-adrenergic receptors per lymphocyte in normal subjects, drug-free asthmatics and patients taking beta-stimulants were 1146 +/- 98, 845 +/- 114 and 582 +/- 47 sites/cell (mean +/- SE), respectively. The differences were statistically significant (P less than 0.05) among these groups, while no statistically significant differences were found in dissociation constants. A 42% decrease in the number of beta-adrenergic receptors per lymphocyte after administration of 6 mg/day of terbutaline for 7 days was noted in four volunteers. There was significant correlation (r = 0.68, P less than 0.01) between the number of beta-adrenergic receptors per lymphocyte and the percentage increase in blood sugar 20 min after subcutaneous injection of 4 micrograms/kg epinephrine. There was also significant correlation (r = 0.78, P less than 0.005) between the number of beta-adrenergic receptors per lymphocyte and the respiratory threshold for acetylcholine. These results suggest that beta-blockade and bronchial hypersensitivity in asthmatic patients may in part be due to a decreased number of beta-adrenergic receptors.     

Long-term study of the frequency of Escherichia coli and Klebsiella pneumoniae isolates producing extended-spectrum β-lactamases

In total, 438 (1.7%) Escherichia coli and 125 (3.98%) Klebsiella pneumoniae isolates were found to be producers of extended-spectrum beta-lactamase (ESBL) during 1995-2003 in southern Spain. There was a significant increase in the frequency of ESBL-producing E. coli isolates, from < 0.36% before 1999 to 4.8% in 2003, while the frequency of ESBL-producing K. pneumoniae isolates decreased during the same period. The most common ESBLs detected in K. pneumoniae were SHV type, whereas both CTX-M and SHV types were detected in E. coli. In addition, E. coli isolates showed greater clonal diversity (84 distinct REP-PCR patterns, compared with five in K. pneumoniae), fewer enzymes per isolate, and a higher number of isolates recovered from outpatients. These differences may have implications for the control measures that should be used for these two microorganisms.