Characterising health care-associated bloodstream infections in public hospitals in Queensland, 2008-2012

Antibody-Mediated Serum Resistance Protects Pseudomonas aeruginosa During Bloodstream Infections

BACKGROUND

Pseudomonas aeruginosa is a frequent pathogen isolated from bacterial bloodstream infection (BSI) and is associated with high mortality. To survive in the blood, P aeruginosa must resist the bactericidal action of complement (ie, serum killing). Antibodies usually promote serum killing through the classical complement pathway; however, "cloaking antibodies" (cAbs) have been described, which paradoxically protect bacteria from serum killing. The relevance of cAbs in P aeruginosa BSI is unknown.

METHODS

Serum and P aeruginosa were collected from a cohort of 100 patients with BSI. Isolates were tested for sensitivity to healthy control serum (HCS). cAb prevalence was determined in sera. Patient sera were mixed with HCS to determine if killing of the matched isolate was inhibited.

RESULTS

Overall, 36 patients had elevated titers of cAbs, and 34 isolates were sensitive to HCS killing. Fifteen patients had cAbs and HCS-sensitive isolates; of these patients, 14 had serum that protected their matched bacteria from HCS killing. Patients with cAbs were less likely to be neutropenic or have comorbidities.

CONCLUSIONS

cAbs are prevalent in patients with P aeruginosa BSI and allow survival of otherwise serum-sensitive bacteria in the bloodstream. Generation of cAbs may be a risk factor for the development of BSI.

Epidemiology of Bloodstream Infections and Antimicrobial Susceptibility Pattern in ICU and Non-ICU Wards: A Four-Year Retrospective Study in Isfahan, Iran

Background

Bloodstream infections (BSIs) are one of the causes of morbidity and mortality in hospitalised patients. This study evaluated BSI's incidence, trend, antimicrobial susceptibility patterns and mortality in AL Zahra Hospital in Isfahan, Iran.

Materials and Methods

This retrospective study was conducted in AL Zahra Hospital from March 2017 to March 2021. The Iranian nosocomial infection surveillance system was used for data gathering. The data included demographic and hospital data, type of bacteria, and antibiotic susceptibility findings and were analysed in SPSS-18 software.

Results

The incidence of BSIs was 1.67% and 0.47%, and the mortality was 30% and 15.2% in the intensive care unit (ICU) and non-ICU wards, respectively. In the ICU, the mortality was correlated with the use of the catheter, type of organism and year of study, but in non-ICU, correlated with age, gender, use of the catheter, ward, year of study and duration between the incidence of BSIs and discharging/death. Staphylococcus epidermidis, Acinetobacter spp. and Klebsiella spp. were the most frequent germs isolated in all wards. Vancomycin (63.6%) and Gentamycin (37.7%) for ICU and Vancomycin (55.6%) and Meropenem (53.3) for other wards were the most sensitive antibiotics.

Conclusion

Despite the few rate of BSI in the last four years in AL Zahra Hospital, our data showed that its incidence and mortality in the ICU ward are significantly more than in other hospital wards. We recommend prospective multicentre studies to know the total incidence of BSI, local risk factors and patterns of pathogens causing BSI.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Effect of infusion set replacement intervals on catheter-related bloodstream infections (RSVP): a randomised, controlled, equivalence (central venous access device)-non-inferiority (peripheral arterial catheter) trial

BACKGROUND

The optimal duration of infusion set use to prevent life-threatening catheter-related bloodstream infection (CRBSI) is unclear. We aimed to compare the effectiveness and costs of 7-day (intervention) versus 4-day (control) infusion set replacement to prevent CRBSI in patients with central venous access devices (tunnelled cuffed, non-tunnelled, peripherally inserted, and totally implanted) and peripheral arterial catheters.

METHODS

We did a randomised, controlled, assessor-masked trial at ten Australian hospitals. Our hypothesis was CRBSI equivalence for central venous access devices and non-inferiority for peripheral arterial catheters (both 2% margin). Adults and children with expected greater than 24 h central venous access device-peripheral arterial catheter use were randomly assigned (1:1; stratified by hospital, catheter type, and intensive care unit or ward) by a centralised, web-based service (concealed before allocation) to infusion set replacement every 7 days, or 4 days. This included crystalloids, non-lipid parenteral nutrition, and medication infusions. Patients and clinicians were not masked, but the primary outcome (CRBSI) was adjudicated by masked infectious diseases physicians. The analysis was modified intention to treat (mITT). This study is registered with the Australian New Zealand Clinical Trials Registry ACTRN12610000505000 and is complete.

FINDINGS

Between May 30, 2011, and Dec, 9, 2016, from 6007 patients assessed, we assigned 2944 patients to 7-day (n=1463) or 4-day (n=1481) infusion set replacement, with 2941 in the mITT analysis. For central venous access devices, 20 (1·78%) of 1124 patients (7-day group) and 16 (1·46%) of 1097 patients (4-day group) had CRBSI (absolute risk difference [ARD] 0·32%, 95% CI -0·73 to 1·37). For peripheral arterial catheters, one (0·28%) of 357 patients in the 7-day group and none of 363 patients in the 4-day group had CRBSI (ARD 0·28%, -0·27% to 0·83%). There were no treatment-related adverse events.

INTERPRETATION

Infusion set use can be safely extended to 7 days with resultant cost and workload reductions.

FUNDING

Australian National Health and Medical Research Council.

Epidemiology and Pathogenesis of Staphylococcus Bloodstream Infections in Humans: a Review

Staphylococci are among the most frequent human microbiota components associated with the high level of bloodstream infection (BSI) episodes. In predisposed patients, there is a high risk of transformation of BSI episodes to sepsis. Both bacterial and host factors are crucial for the outcomes of BSI and sepsis. The highest rates of BSI episodes were reported in Africa, where these infections were up to twice as high as the European rates. However, there remains a great need to analyze African data for comprehensive quantification of staphylococcal BSI prevalence. The lowest rates of BSI exist in Australia. Asian, European, and North American data showed similar frequency values. Worldwide analysis indicated that both Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are the most frequent BSI agents. In the second group, the most prevalent species was Staphylococcus epidermidis, although CoNS were not identified at the species level in many studies. The lack of a significant worldwide decrease in BSI episodes indicates a great need to implement standardized diagnostic methods and research etiological factors using advanced genetic methods.

Trends of Antimicrobial Resistance of Sepsis Pathogens at a University Hospital in New Delhi, India

Knowledge of the aetiological agents and its susceptibility to antimicrobial agents enables the clinician to initiate appropriate empirical antimicrobial therapy and guides diagnostic procedures. The aims of the study were to identify prevalence of bacterial pathogens causing sepsis and observe their antimicrobial resistance trends in hospitalized patients. A prospective cohort study was conducted on patients of sepsis admitted at a university hospital over a period of six months. Pathogens were identified by morphological, biochemical and serological tests as per the American Society for Microbiology. Antibacterial sensitivity of bacterial strains isolated from clinically diagnosed sepsis was carried out by Kirby-Bauer disk diffusion method and interpreted according Clinical and Laboratory Standards Institute guidelines. The data were analyzed by using Statistical Package for Social Sciences, version 16.0 (SPSS 16.0, Chicago, IL, USA). Coagulase negative Staphylococcus (63.5%) and Staphylococcus aureus (23.1%) were the most frequently isolated Gram positive bacteria. Acinetobacter species (31%) and Salmonella typhi (24.1%) were the most frequently isolated Gram negative bacteria. Coagulase negative Staphylococcus showed significant resistance to ciprofloxacin and tetracycline. Acinetobacter species showed significant resistance to ampicillin, amoxicillin and amoxiclav. Salmonella typhi showed significant resistance to ampicillin, amoxicillin, cefotaxime, netilmicin and, tetracycline. Escherichia coli showed significant resistance to ampicillin and netilmicin. All the stains of Staphylococcus aureus were resistant to amoxicillin. Coagulase negative Staphylococcus and Acinetobacter species were predominant Gram positive and Gram negative bacteria, respectively, causing sepsis. Increasing rates of bacterial resistance to commonly use antimicrobial agents were observed.

Healthcare-associated bloodstream infection trends under a provincial surveillance program

OBJECTIVE

BACTOT, Quebec's healthcare-associated bloodstream infection (HABSI) surveillance program has been operating since 2007. In this study, we evaluated the changes in HABSI rates across 10 years of BACTOT surveillance under a Bayesian framework.

DESIGN

A retrospective, cohort study of eligible hospitals having participated in BACTOT for at least 3 years, regardless of their entry date. Multilevel Poisson regressions were fitted independently for cases of HABSI, catheter-associated bloodstream infections (CA-BSIs), non-catheter-associated primary BSIs (NCA-BSIs), and BSIs secondary to urinary tract infections (BSI-UTIs) as the outcome and log of patient days as the offset. The log of the mean Poisson rate was decomposed as the sum of a surveillance year effect, period effect, and hospital effect. The main estimate of interest was the cohort-level rate in years 2-10 of surveillance relative to year 1.

RESULTS

Overall, 17,479 cases and 33,029,870 patient days were recorded for the cohort of 77 hospitals. The pooled 10-year HABSI rate was 5.20 per 10,000 patient days (95% CI, 5.12-5.28). For HABSI, CA-BSI, and BSI-UTI, there was no difference between the estimated posterior rates of years 2-10 compared to year 1. The posterior means of the NCA-BSI rate ratios increased from the seventh year until the tenth year, when the rate was 29% (95% confidence interval, 1%-89%) higher than the first year rate.

CONCLUSIONS

HABSI rates and those of the most frequent subtypes remained stable over the surveillance period. To achieve reductions in incidence, we recommend that more effort be expended in active interventions against HABSI alongside surveillance.

A ten-year review of healthcare-associated bloodstream infections from forty hospitals in Québec, Canada

OBJECTIVE

Healthcare-associated bloodstream infections (HABSI) are a significant cause of morbidity and mortality worldwide. In Québec, Canada, HABSI arising from acute-care hospitals have been monitored since April 2007 through the Surveillance des bactériémies nosocomiales panhospitalières (BACTOT) program, but this is the first detailed description of HABSI epidemiology.

METHODS

This retrospective, descriptive study was conducted using BACTOT surveillance data from hospitals that participated continuously between April 1, 2007, and March 31, 2017. HABSI cases and rates were stratified by hospital type and/or infection source. Temporal trends of rates were analyzed by fitting generalized estimating equation Poisson models, and they were stratified by infection source.

RESULTS

For 40 hospitals, 13,024 HABSI cases and 23,313,959 patient days were recorded, for an overall rate of 5.59 per 10,000 patient days (95% CI, 5.54-5.63). The most common infection sources were catheter-associated BSIs (23.0%), BSIs secondary to a urinary focus (21.5%), and non-catheter-associated primary BSIs (18.1%). Teaching hospitals and nonteaching hospitals with ICUs often had rates higher than nonteaching hospitals without ICUs. Annual HABSI rates did not exhibit statistically significant changes from year to year. Non-catheter-associated primary BSIs were the only HABSI type that exhibited a sustained change across the 10 years, increasing from 0.69 per 10,000 patient days (95% CI, 0.59-0.80) in 2007-2008 to 1.42 per 10,000 patient days (95% CI, 1.27-1.58) in 2016-2017.

CONCLUSIONS

Despite ongoing surveillance, overall HABSI rates have not decreased. The effect of BACTOT participation should be more closely investigated, and targeted interventions along alternative surveillance modalities should be considered, prioritizing high-burden and potentially preventable BSI types.

Dalbavancin in the treatment of different gram-positive infections: a real-life experience

Dalbavancin is a lipoglycopeptide with a very prolonged half-life enabling treatment with a single intravenous administration that has been approved to treat complicated skin and soft-tissue infections. Information on the efficacy and safety of dalbavancin in other situations is very scarce. This retrospective study included adult patients who received at least one dose of dalbavancin between 2016 and 2017 in 29 institutions in Spain. The primary objective was to report the use of dalbavancin in clinical practice, including its efficacy and tolerability. The potential impact of dalbavancin on reducing the length of hospital stay and hospital costs was also evaluated. A total of 69 patients received dalbavancin during the study period (58.0% male; median age 63.5 years). Dalbavancin was used to treat prosthetic joint infection (29.0%), acute bacterial skin and skin-structure infection (21.7%), osteomyelitis (17.4%) and catheter-related bacteraemia (11.6%). These infections were mainly caused by Staphylococcus aureus (27 isolates), coagulase-negative staphylococci (24 isolates) and Enterococcus spp. (11 isolates). All but two patients received previous antibiotics for a median of 18 days. Dalbavancin was administered for a median of 21 days (range 7-168 days), and concomitant antimicrobial therapy was prescribed to 25 patients (36.2%). The overall clinical success rate of dalbavancin was 84.1%. Adverse events, mainly mild in intensity, were reported in nine patients. Overall, dalbavancin was estimated to reduce hospitalisation by 1160 days, with an estimated overall cost reduction of €211 481 (€3064 per patient). Dalbavancin appears to be an effective therapy for many serious Gram-positive infections.

Nasal carriage of methicillin-resistant coagulase-negative staphylococci in healthy humans is associated with occupational pig contact in a dose-response manner

This study aimed to explore the association between occupational pig contact and human methicillin-resistant coagulase-negative staphylococci (MRCoNS) carriage. We conducted a cross-sectional study of pig exposed participants and controls in Guangdong, China, using a multi-stage sampling design. Participants provided a nasal swab for MRCoNS analysis and resulting isolates were tested for antibiotic susceptibility. The dose-response relation was examined using log binomial regression or Poisson regression models. The adjusted prevalence of MRCoNS carriage in pig exposed participants was 1.67 times (95% CI: 1.32-2.11) higher than in controls. The adjusted average number of resistance to different antibiotic classes of MRCoNS isolates from pig exposed participants was 1.67 times (95% CI: 1.46-1.91) higher than those from controls. Notably, we found the frequency and duration of occupational pig contact was associated with increased prevalence and increased number of resistance to different antibiotic classes of MRCoNS in a dose-response manner. When examining these relations by MRCoNS species, there was still evidence of similar exposure-response relations. Additionally, the proportion of tetracycline-resistant and tet(M)-containing MRCoNS isolates was significantly higher in pig exposed participants than in controls. These findings suggested a potential transmission of MRCoNS from livestock to humans by occupational livestock contact, and the presence of phenotypic and genotypic tetracycline resistance may aid in the differentiation of animal origins of MRCoNS isolates.

Candida albicans infection and intestinal immunity

Fungal infections cause high rates of morbidity and mortality in intensive care and immunocompromised patients, and can represent a life-threatening disease. As a microorganism commonly found in the intestine, Candida albicans (C. albicans) can invade the gut epithelium barrier via microfold cells and enter the bloodstream. The defensive potential of the intestinal barrier against invasive C. albicans is dependent on innate and adaptive immune responses which enable the host to eliminate pathogenic fungi. The lamina propria layer of the intestine contains numerous immune cells capable of inducing an innate cellular immune response against invasive fungi. This review focuses on the immune response triggered by a C. albicans infection in the intestine.