Studies on climate variables and food pathogens are either pathogen- or region-specific, necessitating a consolidated view on the subject. This study aims to systematically review all studies on the association of ambient temperature and precipitation on the incidence of gastroenteritis and bacteraemia from Salmonella, Shigella, Campylobacter, Vibrio, and Listeria species. PubMed, Ovid MEDLINE, Scopus, and Web of Science databases were searched up to 9 March 2023. We screened 3,204 articles for eligibility and included 83 studies in the review and three in the meta-analysis. Except for one study on Campylobacter, all showed a positive association between temperature and Salmonella, Shigella, Vibrio sp., and Campylobacter gastroenteritis. Similarly, most of the included studies showed that precipitation was positively associated with these conditions. These positive associations were found regardless of the effect measure chosen. The pooled incidence rate ratio (IRR) for the three studies that included bacteraemia from Campylobacter and Salmonella sp. was 1.05 (95 per cent confidence interval (95% CI): 1.03, 1.06) for extreme temperature and 1.09 (95% CI: 0.99, 1.19) for extreme precipitation. If current climate trends continue, our findings suggest these pathogens would increase patient morbidity, the need for hospitalization, and prolonged antibiotic courses.

Longitudinal studies on the variations of phenotypic and genotypic characteristics of K. pneumoniae across two decades are rare. We aimed to determine the antimicrobial susceptibility and virulence factors for K. pneumoniae isolated from patients with bacteraemia or urinary tract infection (UTI) from 1999 to 2022. A total of 699 and 1,267 K. pneumoniae isolates were isolated from bacteraemia and UTI patients, respectively, and their susceptibility to twenty antibiotics was determined; PCR was used to identify capsular serotypes and virulence-associated genes. K64 and K1 serotypes were most frequently observed in UTI and bacteraemia, respectively, with an increasing frequency of K20, K47, and K64 observed in recent years. entB and wabG predominated across all isolates and serotypes; the least frequent virulence gene was htrA. Most isolates were susceptible to carbapenems, amikacin, tigecycline, and colistin, with the exception of K20, K47, and K64 where resistance was widespread. The highest average number of virulence genes was observed in K1, followed by K2, K20, and K5 isolates, which suggest their contribution to the high virulence of K1. In conclusion, we found that the distribution of antimicrobial susceptibility, virulence gene profiles, and capsular types of K. pneumoniae over two decades were associated with their clinical source.

In mainland China, the clinical, epidemiological and genetic features of non-O1/non-O139 Vibrio cholerae (NOVC) bacteraemia have been scarcely investigated. Herein, we describe a patient with NOVC bacteraemia diagnosed in our hospital and present a retrospective analysis of literature reports of 32 other cases in China, detailing the clinical epidemiology, antibiotic resistance and molecular characteristics of isolates. Most patients were male (84.8%; median age, 53 years) and had predisposing factors, such as cirrhosis, malignant tumours, blood diseases and diabetes. In addition to fever, gastroenteritis was the most frequent presenting symptom. The mortality rate during hospitalisation was 12.1%. NOVC bacteraemia cases were more common in June–August, with the majority in coastal provinces and the Yangtze River basin. Only 42.4% of cases were attributed to consumption of marine (aquatic) products. Tetracycline, third-generation cephalosporins, and fluoroquinolones were the most effective antimicrobial agents, and the highest frequencies of resistance were recorded for ampicillin/sulbactam (37.5%), amoxicillin/clavulanic acid (33.3%), ampicillin (29.2%) and sulfamethoxazole (20%). Multi-drug resistant isolates were not detected. Limited data indicate that ctxAB and tcpA genes were absent in all NOVC isolates but other putative virulence genes (hlyA, toxR, hap and rtxA) were common. Ten multilocus sequence types were identified with marked genetic heterogeneity between different isolates. As clinical manifestations of NOVC bacteraemia may vary widely, and isolates exhibit genetic diversity, clinicians and public health experts should be alerted to the possibility of infection with this pathogen because of the high prevalence of liver disease in China.

Although patients with end-stage renal disease (ESRD) are known to be at high risk for developing bloodstream infections (BSI), the risk associated with lesser degrees of renal dysfunction is not well defined. We sought to determine the risk for acquiring and dying from community-onset BSIs among patients with renal dysfunction. A retrospective, population-based cohort study was conducted among adult residents without ESRD in the western interior of British Columbia. Estimated glomerular filtration rates (eGFR) were determined for cases and incidence rate ratios (IRR) were calculated using prevalence estimates. Overall, 1553 episodes of community-onset BSI were included of which 39%, 32%, 17%, 9%, 2% and 1% had preceding eGFRs of ≥90, 60–89, 45–59, 30–44, 15–29 and <15 ml/min/m2, respectively. As compared to those with eGFR ≥60 ml/min/m2, patients with eGFR 30–59 ml/min/m2 (IRR 4.4; 95% confidence interval (CI) 3.9–4.9) and eGFR <30 ml/min/m2 (IRR 7.0; 95% CI 5.0–9.5) were at significantly increased risk for the development of community-onset BSI. An eGFR <30 ml/min/m2 was an independent risk factor for death (odds ratio 2.3; 95% CI 1.01–5.15). Patients with renal dysfunction are at increased risk for developing and dying from community-onset BSI that is related to the degree of dysfunction.

The objective was to compare the performance of the updated Charlson comorbidity index (uCCI) and classical CCI (cCCI) in predicting 30-day mortality in patients with Staphylococcus aureus bacteraemia (SAB). All cases of SAB in patients aged ⩾14 years identified at the Microbiology Unit were included prospectively and followed. Comorbidity was evaluated using the cCCI and uCCI. Relevant variables associated with SAB-related mortality, along with cCCI or uCCI scores, were entered into multivariate logistic regression models. Global model fit, model calibration and predictive validity of each model were evaluated and compared. In total, 257 episodes of SAB in 239 patients were included (mean age 74 years; 65% were male). The mean cCCI and uCCI scores were 3.6 (standard deviation, 2.4) and 2.9 (2.3), respectively; 161 (63%) cases had cCCI score ⩾3 and 89 (35%) cases had uCCI score ⩾4. Sixty-five (25%) patients died within 30 days. The cCCI score was not related to mortality in any model, but uCCI score ⩾4 was an independent factor of 30-day mortality (odds ratio, 1.98; 95% confidence interval, 1.05–3.74). The uCCI is a more up-to-date, refined and parsimonious prognostic mortality score than the cCCI; it may thus serve better than the latter in the identification of patients with SAB with worse prognoses.

We investigated the clinical predictors of methicillin-resistance and their impact on mortality in 371 patients with Staphylococcus aureus bacteraemia identified from two prospective multi-centre studies. Methicillin resistant S. aureus (MRSA) accounted for 42.2% of community-onset and 74.5% of hospital-onset cases. No significant clinical difference was found between patients infected with MRSA vs. methicillin-sensitive S. aureus (MSSA), except that the former were more likely to have had hospital-onset bacteraemia and received antibiotics in the preceding 90 days. After stratifying according to the acquisition site, prior antibiotic use was the only independent predictor of having MRSA in both community-onset and hospital-onset cases. The frequency of inappropriate empirical antibiotic therapy was higher in patients with MRSA than in those with MSSA bacteraemia. However, methicillin resistance was not a predictor of mortality in patients and the clinical characteristics and outcomes of both MRSA and MSSA bacteraemia were similar. This study indicates that there are no definitive clinical or epidemiological risk factors which could distinguish MRSA from MSSA cases with the exception of the previous use of antibiotics for having MRSA bacteraemia, which emphasises the prudent use of glycopeptide treatment of patients at risk for invasive MRSA infections.

Thrombocytopenia is common in patients with invasive bacterial infections. Bacteria can activate platelets, but it is unclear if this affects platelet count. The aim of this study was to examine whether bacteraemia with Staphylococcus aureus, which readily activate human platelets, was more likely to be complicated by thrombocytopenia than bacteraemia with Escherichia coli or Streptococcus pneumoniae with different abilities to activate platelets.

We compared information from 600 adult patients with community-acquired bacteraemia with S. aureus (n = 140), E. coli (n = 420) and S. pneumoniae (n = 40) in Southern Sweden, 2012, linking information on positive blood cultures from microbiological databases and medical charts. The proportion of patients with thrombocytopenia (platelet count <150 × 109/ml) was calculated. Logistic regression was used to estimate the odds ratios (OR) for thrombocytopenia according to bacterial species adjusted for confounders.

The proportion of thrombocytopenia was 29% in S. aureus, 28% in E. coli and 20% in S. pneumonia bacteraemia (P = 0.50), corresponding to an OR of 1.2 (95% confidence interval 0.7–1.9) for thrombocytopenia for S. aureus as compared with E. coli or S. pneumoniae, adjusted for confounders.

This study indicates that platelet activation by bacteria is not a major causative mechanism in sepsis-associated thrombocytopenia.

Bacteraemia caused by Escherichia coli are particularly frequent and severe, contrasting with the commensal character of the strains found in the digestive tract. A better understanding of the relationships between strains of both origins is needed to unravel the pathogenesis of this disease. Two hundred and forty-three commensal strains were compared to 243 bacteraemic strains isolated from adult hosts matched in terms of gender and age, and from similar location and epoch. Phylogenetic grouping, O-type determination, virulence factor content and antibiotic resistance were compared. Compared to commensal strains, the bacteraemic strains were characterized by a higher proportion of B2, C and D phylogroups, and a lower proportion of A, E and F phylogroups. They also had a lower proportion of the B2 subgroup IV (STc141), a higher proportion of virulence factors, and a higher frequency of antibiotic resistance. These differences were more marked for the bacteraemic strains of urinary tract origin with the presence of specific clones, whereas the bacteraemic strains of digestive origin remained non-significantly different from the commensal strains, except for their antibiotic resistance. Thus, two levels of specialization from commensal strains were demonstrated in the bacteraemic strains: resistance to antibiotics in all cases, and virulence for those of urinary tract origin.

We report the case of a 2-year-old boy with severe Langerhans cell histiocytosis who had tricuspid endocarditis caused by Staphylococcus lugdunensis and required surgery despite appropriate antimicrobial therapy. Through this case and literature review of endocarditis caused by S. lugdunensis in children, we highlight pitfalls and mistakes to be avoided in the management of this rare but serious infection.

This study was part of a bloodstream infection surveillance programme that prospectively collected data on consecutive patients with bacteraemia in our institution from 1991 to 2012. We included 2092 bacteraemias in neutropenic patients. Shock and mortality accounted for 299 and 349 cases, respectively (14% and 17%). The main microorganisms isolated were coagulase-negative staphylococci (CoNS, 634, 30%), Escherichia coli (468, 22%) and Pseudomonas aeruginosa (235, 11%). During 2006–2012, there were 155 (27%) E. coli isolates; of these, 73% were fluoroquinolone resistant and 26% cefotaxime resistant. The independent risk factors for mortality were shock on presentation, rapidly fatal prognosis of underlying disease, corticosteroid use, and polymicrobial bacteraemia. Factors associated with lower mortality were the isolation of CoNS [odds ratio (OR) 0·38, 95% confidence interval (CI) 0·20–0·73, P = 0·004] and empirical therapy with amikacin (OR 0·50, 95% CI 0·29–0·88, P = 0·016). The progressive increase of Gram-negative microorganisms resistant to antibiotics influences the choice of empirical treatment in febrile neutropenia and in our experience, the addition of amikacin could be beneficial for such patients.

We sought to examine the factors associated with bacteraemia and their outcome in children with pneumonia and severe acute malnutrition (SAM). All SAM children of either sex, aged 0–59 months, admitted to the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh with radiologically confirmed pneumonia from April 2011 to July 2012 were enrolled (n = 405). Comparison was made between pneumonic SAM children with (cases = 18), and without (controls = 387) bacteraemia. The death rate was significantly higher in cases than controls (28% vs. 8%, P < 0·01). In logistic regression analysis, after adjusting for potential confounders, the SAM children with pneumonia and bacteraemia more often had a history of lack of bacillus Calmette-Guérin (BCG) vaccination (odds ratio 7·39, 95% confidence interval 1·67–32·73, P < 0·01). The results indicate the importance of continuation of BCG vaccination which may provide benefit beyond its primary purpose.

The clinical and microbiological characteristics of catheter-related bloodstream infection (CR-BSI) due to uncommon microorganisms was assessed in a retrospective case-control study over a 9-year period in a tertiary teaching hospital. Uncommon microorganisms were defined as those representing <0·5% of all CR-BSI. Diagnosis of CR-BSI required that the same microorganism was grown from at least one peripheral venous blood culture and a catheter tip culture. Thirty-one episodes of CR-BSI were identified due to 13 different genera and these accounted for 2·3% of all CR-BSI in the hospital. Although these infections were not associated with increased mortality, they occurred in patients with more severe underlying conditions who were receiving prolonged antibiotic therapy.

To explore the specificities of Escherichia coli bacteraemia in the elderly, the demographic, clinical and bacteriological characteristics and in-hospital mortality rate of ‘young’ (18–64 years, n = 395), ‘old’ (65–79 years, n = 372) and ‘very old’ (⩾80 years, n = 284) adult patients of the multicentre COLIBAFI cohort study were compared. Clinical and bacteriological risk factors for death were jointly identified by logistic regression and multivariate analysis within each group. ‘Young’ and ‘old’ patients had more comorbidities than ‘very old’ patients (comorbidity score: 1·5 ± 1·3 and 1·6 ± 1·2 vs. 1·2 ± 1·2, respectively; P < 0·001), and were more frequently nosocomially infected (22·3% and 23·8% vs. 8·8%, respectively; P < 0·001). ‘Old’ patients had the poorest prognosis (death rate: 16·4% vs.10·4% for ‘young’ and 12·0% for ‘very old’ patients, respectively; P = 0·039). Risk factors for death were age group-specific, suggesting a host–pathogen relationship evolving with age.

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia cause significant morbidity and mortality in hospitalized patients. Using a nested case-control design, 204 MRSA bacteraemia cases were compared to 301 unmatched methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia controls and were matched 1:2 with non-infected controls. The independent risk factors for MRSA bacteraemia compared to MSSA bacteraemia were older age (P = 0·048), major organ transplant during current hospital stay (P = 0·016) and quinolone use (P = 0·016). Cases were more likely than non-infected controls to have renal failure (P = 0·003), cirrhosis (P = 0·013), and a central venous catheter (P = 0·003) after controlling for other risk factors. This large case-control study made it possible to assess risk factors for MRSA bacteraemia using two sets of controls and showed that risk factors differed greatly depending on the control group chosen. These results confirm the need for careful selection of appropriate control groups and the need to carefully adjust for underlying severity of illness.

This 10-year retrospective study assessed the epidemiology and outcomes of patients with Fusobacterium bacteraemia (FB) at a tertiary-care hospital in the USA – this is the second study focusing on FB in adults to be conducted in the USA in 30 years. Demographic, clinical, laboratory, treatment, and outcome data were collected and statistically analysed. Nineteen patients with FB were identified, representing 0·11% of bacteraemia cases. Mean age was 58·6 years with equal gender distribution. Common comorbidities included cardiovascular disease (CVD) and immunosuppression. Thirty-day mortality was 21·1%, and 68·4% of FB patients required intensive care unit (ICU) admission. Elevated creatinine levels and mental status changes were associated with higher mortality (P = 0·0181 and 0·0374, respectively). CVD, diabetes, and ICU admission were associated with increased length of hospital stay (P = 0·0017, 0·0010, and 0·0379, respectively). The prevalence of FB at our hospital was very low, with poor outcomes associated with increased creatinine level, mental status changes, CVD, diabetes and ICU admission.

The aim of the present study was to analyse the bacteriological factors during the process of dental alveolitis, relating it to a higher incidence of bacteraemia in adult rats subjected to neonatal malnutrition. We used forty male Wistar rats, suckled by mothers fed a diet during lactation containing 17 % protein in the nourished group (N) or 8 % protein in the undernourished group (UN). After weaning, the animals were given the Labina standard diet. After 90 d, these animals underwent upper right incisor extraction and induction of alveolitis. The oral microbiota was obtained using a swab and blood culture through venous blood. These procedures were performed before the extraction, 5 min after extraction, on the 21st day after alveolitis for groups N-21 and UN-21 and on the 28th day after alveolitis for groups N-28 and UN-28. Data were expressed as means and standard deviations for parametric data, and as medians and interquartile intervals for non-parametric data. Statistical significance was considered by assuming a critical level of 5 %. Before and after extraction, lower bacterial growth was observed per colony-forming unit (CFU) in the perialveolar region of the upper right incisors of undernourished animals, while the opposite was true after alveolitis, when a larger number of CFU was observed in these animals. The percentage of positive blood cultures obtained after alveolitis was greater in the undernourished animals. The present study thus demonstrated the influence of neonatal malnutrition in the perialveolar microbiota and in the development of bacteraemia after dental alveolitis.

Referral bias can influence the results of studies performed at tertiary-care centres. In this study, we evaluated demographic and microbiological factors that influenced referral of patients with Gram-negative bloodstream infection (BSI). We identified 2919 and 846 unique patients with Gram-negative BSI in a referral cohort of patients treated at Mayo Clinic Hospitals and a population-based cohort of Olmsted County, Minnesota, residents between 1 January 1998 and 31 December 2007, respectively. Multivariable logistic regression analysis was used to determine factors associated with referral. Elderly patients aged ⩾80 years with Gram-negative BSI were less likely to be referred than younger patients [odds ratio (OR) 0·43, 95% confidence intervals (CI) 0·30–0·62] as were females (OR 0·63, 95% CI 0·53–0·74). After adjusting for age and gender, bloodstream isolates of Escherichia coli (OR 0·50, 95% CI 0·43–0·58) and Proteus mirabilis (OR 0·49, 95% CI 0·30–0·82) were underrepresented in the referral cohort; and Pseudomonas aeruginosa (OR 2·26, 95% CI 1·70–3·06), Enterobacter cloacae (OR 2·31, 95% CI 1·53–3·66), Serratia marcescens (OR 2·34, 95% CI 1·33–4·52) and Stenotrophomonas maltophilia (OR 17·94, 95% CI 3·98–314·43) were overrepresented in the referral cohort. We demonstrated that demographic and microbiological characteristics of patients with Gram-negative BSI had an influence on referral patterns. These factors should be considered when interpreting results of investigations performed at tertiary-care centres.

The incidence of bacteraemia has increased considerably during the last decades. This may be related to population ageing, increased use of invasive procedures, and increased ascertainment of bacteraemia. Generalized additive and generalized linear models were used to analyse the impact of four successive improvements in blood culture methodology on the recovery of prevalent blood culture isolates while simultaneously controlling for underlying time trend and seasonal variation. Between 1981 and 2006, 20 091 bacteraemias comprising 22 800 blood culture isolates were diagnosed. The changes in methodology increased the recovery of some bacterial groups; the greatest impact was observed for Enterobacteriaceae, pneumococci and Staphylococcus aureus whereas recovery of β-haemolytic streptococci, Pseudomonas aeruginosa, other Gram-negative aerobes, and fungi was not affected. Changes in blood culture methodology should be taken into account when assessing time trends of bacteraemia.