Is it in their eyes? Correlation between microorganisms isolated from bronchial aspirates and conjunctival swabs in a Pediatric Intensive Care Unit.

OBJECTIVE: Our observational, retrospective study aimed to determine the correlation between bacteria isolated from bronchial aspirates of pediatric ICU patients (PICU) with respiratory infections and those obtained from conjunctival swabs of the same patients exhibiting clinical conjunctivitis. METHODS: Throughout the period from 2015 to 2022, we reviewed all clinically significant bronchial aspirates (≥105 CFU/mL) and positive conjunctival swabs obtained from PICU patients. These records were retrieved from the microbiology database, cross-referencing the data to identify patients who tested positive for both during the same clinical episode. RESULTS: The median age of the patients was 5 months (interquartile range: 1-7). Among the cohort, twenty-one patients exhibited positivity in both bronchial aspirate and conjunctival swab samples, showcasing a microbial match in 85.71% of cases (18 out of 21). The most frequently isolated microorganisms were Haemophilus influenzae (55.6%), followed by Pseudomonas aeruginosa (14.3%), Klebsiella aerogenes (9.5%), and Escherichia coli, Stenotrophomonas maltophilia, and Enterobacter cloacae, each accounting for 4.8% of the isolates. CONCLUSIONS: Our study demonstrates a strong concordance between the isolated microorganisms from both samples in patients presenting clear symptoms of clinical conjunctivitis. These findings provide a basis for future prospective studies that may leverage conjunctival swabs as a predictive tool for identifying microorganisms involved in respiratory infections.

Rapid AST: Possibility of inferring resistance mechanisms with complex phenotypes.

The new automated systems designed for rapid performance of AST have significantly reduced the response time for susceptibility testing of microorganisms causing bacteremia and sepsis. The Accelerate Pheno® system (AAC) is one such system. Our objective for this study was to determine whether the AAC system is capable of providing an accurate susceptibility profile to infer resistance mechanisms in different carbapenemase-producing isolates when compared to the MicroScan WalkAway System (MWS). Disk diffusion method was also performed on all isolates as a reference method. Additionally, we compared the results obtained with the routine AST production system. We selected 19 isolates from the cryobank of the Microbiology department, all of which were carbapenemase-producing gram-negative bacilli. AAC was able to identify and infer the resistance of a total of 10 isolates, with an EA and CA of 84.2% for meropenem and 88.2% and 64.7% for ertapenem EA and CA, respectively. If we consider the disk diffusion technique, the CA was 57.9% and 76.5% for meropenem and ertapenem. However, in the presence of carbapenemases, AAC was not able to provide adequate MICs or infer the resistance mechanisms of the isolates accurately. Further studies with a larger number of isolates, including the new antibiotics ceftolozane/tazobactam and ceftazidime/avibactam, are needed for a more comprehensive comparison.

Antibiotic resistance in bloodstream isolates from high-complexity paediatric units in Madrid, Spain: 2013-2021.

BACKGROUND: Antimicrobial resistance (AMR) has become a significant challenge in high-complexity healthcare settings. AIM: To evaluate the prevalence of AMR in bloodstream isolates from high-complexity paediatric units in Spain over a nine-year period. METHODS: A retrospective observational multicentre study was conducted in three tertiary hospitals, analysing bloodstream isolates from patients aged <18 years admitted to the paediatric intensive care, neonatology, and oncology-haematology units between 2013 and 2021. Demographics, antimicrobial susceptibility, and resistance mechanisms were analysed in two periods (2013-2017 and 2017-2021). FINDINGS: In all, 1255 isolates were included. AMR was more prevalent in older patients and those admitted to the oncology-haematology unit. Multidrug resistance was observed in 9.9% of Gram-negative bacteria (GNB); 20.0% of P. aeruginosa vs 8.6% of Entero-bacterales (P < 0.001), with an increase in Enterobacterales from 6.2% to 11.0% between the first and the second period (P = 0.021). Difficult-to-treat resistance was observed in 2.7% of GNB; 7.4% of P. aeruginosa vs 1.6% of Enterobacterales (P < 0.001), with an increasing trend in Enterobacterales from 0.8% to 2.5% (P = 0.076). Carbapenem resistance among Enterobacterales increased from 3.5% to 7.2% (P = 0.029), with 3.3% producing carbapenemases (67.9% VIM). Meticillin resistance was observed in 11.0% of S. aureus and vancomycin resistance in 1.4% of Enterococcus spp., with both rates remaining stable throughout the study period. CONCLUSION: This study reveals a high prevalence of AMR in high-complexity paediatric units. Enterobacterales showed a concerning increasing trend in resistant strains, with higher rates among older patients and those admitted to oncology-haematology units.

Optimized identification of microorganisms directly from positive blood cultures by MALDI-TOF to improve antimicrobial treatment.

OBJECTIVE: Bacteriemia is a major cause of morbidity and mortality among hospitalized patients worldwide. Early identification of microorganisms from blood culture can lead to improvement of treatment and outcomes. METHODS: The study was divided into two phases. The first phase when a comparison of the methods was made to check the concordance between them, using as a reference the standard method implemented in the laboratory. In a second phase, both methods are combined. We used the rapid identification method and when it could not identify we used the standard method. The microorganisms that were not identified by either of the two methods were identified from colony at 24 hours. RESULTS: A total of 589 microbial positive blood cultures have been included in the present study. With the rapid method we obtained 96% and 88% identification results for Gram-negative bacilli (GNB) and Gram-positive cocci (GPC) respectively. In this study we observed that the combination of the rapid and standard method achieved identifications of 98% and 97% for GNB and GPC respectively. CONCLUSIONS: The data analysed shows that both methods combined perform better than individually. We achieved an optimization of the identification of microorganisms directly from positive blood cultures by MALDI-TOF. This combination identified 98% of the microorganisms in between ten minutes to one hour and a half since the blood culture flagged positive.

Evaluation of a lateral flow immunoassay to detect CTX-M extended-spectrum ß-lactamases (ESBL) directly from positive blood cultures for its potential use in Antimicrobial Stewardship programs.

OBJECTIVE: Bloodstream infections (BSI) caused by extended-spectrum beta-lactamases Enterobacteriaceae (ESBL-E) are associated with high rates of treatment failure and increased mortality, especially when appropriate antimicrobial therapy is delayed. Our aim was to evaluate the anticipation of ESBLs detection and the potential improvement of the time response of the Vitek 2 System (BioMérieux; France). METHODS: We compared this lateral flow immunoassay when used directly on fluid from positive blood cultures to the VITEK2 AST system. We evaluated 80 isolates, 61 tested directly on fluid from positive blood cultures and 19 tested on fluid from blood cultures spiked with known ESBL positive and negative organisms. RESULTS: The concordance between the CTX-LFIA and the reference method (Vitek 2) had a Cohen´s Kappa coefficient of 0.97, indicating a particularly good correlation between both compared methods. CONCLUSIONS: This lateral flow immunoassay can be more rapid than the Vitek 2 for earlier presumptive identification of CTX-M ESBLs and can be useful to anticipate results and the adjustment of antimicrobial therapy.

Bloodstream infection due to Herbaspirillum sp.: case series and review of literature.

Herbaspirillum species are Gram-negative bacteria belonging to the class Betaproteobacteria, order Burkholderiales. The phylogenetic and phenotypic similarities among these groups easily lead to species misidentification. Herbaspirillum bacteraemia is an uncommon clinical entity. The objective of this review is to collect information to contribute to the management of this infection. We describe our own case series and review the cases reported in the literature. Cancer appears as the major underlying disease. The main source of bacteraemia was respiratory. Phenotypic identification methods often misidentify this species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and molecular methods identify at genus level, but species assignment is not reliable. Herbaspirillum spp. showed a highly susceptible antimicrobial profile. ß-Lactams showed good activity with low MIC values, except ampicillin. All isolates were resistant to colistin, suggesting an intrinsic resistance mechanism. Herbaspirillum spp. is an uncommon pathogen. MALDI-TOF MS or molecular methods are necessary to achieve a reliable genus identification. These species are not multidrug resistant. Piperacillin/tazobactam or ceftazidime might be a good treatment for this microorganism.

Impact of rapid diagnosis of Staphylococcus aureus bacteremia from positive blood cultures on patient management.

We have performed a retrospective, before-after comparison of turnaround time and therapy adjustment parameters before and after the introduction of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) plus mecA polymerase chain reaction (PCR) for the identification of methicillin-resistant Staphylococcus aureus (MRSA) in positive blood cultures. There were 227 episodes of S. aureus bacteremia during the study periods. The pre-MALDI-TOF and post-MALDI-TOF groups included 133 and 94 patients, respectively. The two rapid methods performed sequentially decreased the turnaround time of MRSA identification by nearly 50% (2.06 ± 1.95 vs. 3.95 ± 1.70 days). There was no significant reduction in the length of hospitalization (28.27 ± 32.16 vs. 28.62 ± 28.75 days). In both groups, the adequacy of the empirical antibacterial therapy was similar (59.49% vs. 51.31%), but the optimization of the therapy was more frequent in the post-MALDI-TOF group. Routine implementation of these techniques provides results earlier than conventional methods and increases the proportion of episodes with adequate change of empirical to directed antimicrobial therapy.

Blood and tissue distribution of posaconazole in a rat model of invasive pulmonary aspergillosis.

Posaconazole is the recommended prophylactic agent in patients at high risk of invasive fungal infection, since adequate drug levels seem to be reached in target sites despite the relatively low levels detected in blood. The objective of this study is to obtain pharmacokinetic (PK) information associated to blood and tissue distribution of posaconazole in an animal model of invasive pulmonary aspergillosis. The PK parameters in lung samples were systematically higher than in serum. After multiple-dose administration of posaconazole, a significant accumulation of the drug was evident in lung tissue. The PK behavior of posaconazole in this particular experimental model is similar to that observed in humans. Thus, we believe this model could be a valid tool to evaluate posaconazole exposure-response relationship.

[Clinical indications for therapeutic drug monitoring of antifungal agents. In the way for optimizing the treatment of fungal infection]. / Indicaciones clínicas de la monitorización de azoles de uso sistémico. Hacia la optimización del tratamiento de la infección fúngica.

Therapeutic drug monitoring as a tool in the management of infectious diseases has been introduced in therapy with anti-infective agents for years. Nowadays, it has taken importance in the management of fungal diseases due to the appearance of new antifungal drugs such as new-generation azoles. These azoles have pharmacokinetic characteristics that hinder a proper use to ensure efficacy and minimize toxicity. Monitoring of serum concentrations may help in the better use of these anti-infective agents, as well as in a better management of drug interactions, infectious disease and adverse effects. It has resulted in saving costs of treatment and in avoiding inadequate dosages. This review will attempt to clarify the role of the antifungal agents Therapeutic Drug Monitoring, highlighting the role of azole compounds.

An invertebrate model to evaluate virulence in Aspergillus fumigatus: the role of azole resistance.

The impact of different mutations in the Aspergillus fumigatus ergosterol biosynthesis pathway on pathogenesis has been evaluated using a simple invertebrate mini host, the caterpillar Galleria mellonella. A set of strains that includes clinical isolates and isogenic mutants with mutations at the cyp51A gene conferring azole resistance were studied. All strains demonstrated a similar in vitro growth pattern and are equally virulent against the insect larvae. These results suggest that in A. fumigatus acquisition of this particular azole-resistance mechanism would not imply any significant change in virulence. G. mellonella may provide a convenient and inexpensive model for the in vivo prescreening of mutants of A. fumigatus, contributing to the generation of a hypotheses that can be further tested in refined experiments in mammalian models.

Reclassification of the Candida haemulonii complex as Candida haemulonii (C. haemulonii group I), C. duobushaemulonii sp. nov. (C. haemulonii group II), and C. haemulonii var. vulnera var. nov.: three multiresistant human pathogenic yeasts.

The Candida haemulonii species complex is currently known as C. haemulonii groups I and II. Here we describe C. haemulonii group II as a new species, Candida duobushaemulonii sp. nov., and C. haemulonii var. vulnera as new a variety of C. haemulonii group I using phenotypic and molecular methods. These taxa and other relatives of C. haemulonii (i.e., Candida auris and Candida pseudohaemulonii) cannot be differentiated by the commercial methods now used for yeast identification. Four isolates (C. haemulonii var. vulnera) differed from the other isolates of C. haemulonii in the sequence of the internal transcribed spacer (ITS) regions of the nuclear rRNA gene operon. The new species and the new variety have a multiresistant antifungal profile, which includes high MICs of amphotericin B (geometric mean MIC, 1.18 mg/liter for C. haemulonii var. vulnera and 2 mg/liter for C. duobushaemulonii sp. nov) and cross-resistance to azole compounds. Identification of these species should be based on molecular methods, such as sequence analysis of ITS regions and matrix-assisted laser desorption ionization-time of flight mass spectrometry.

HPLC/UV or bioassay: two valid methods for posaconazole quantification in human serum samples.

In this paper we report on the development and validation of two different methods for posaconazole quantification from serum samples, HPLC/UV and bioassay. Both methods have been validated according to international guidelines and were also applied to the analysis of 61 trough serum samples from treated patients. A good correlation between both methods was observed. The HPLC method, more laborious and expensive, was demonstrated to be more accurate, precise and faster (analytical range 0.125-16 µg/mL, accuracy between -2.48 and 3.70% and precision between 2.77 and 5.93%, with an analytical run time of 11 min), making it a valuable tool for reference laboratories that centralize high numbers of samples. The microbiological method, however, is simple and offers sufficient precision and accuracy (analytical range 0.125-16 µg/mL, accuracy between -8.10 and 3.77% and a precision between 4.52 and 10.07%), to be used to monitor posaconazole. It may be a valid alternative to chromatographic methods in clinical laboratories without specialized facilities.

Sepsis neonatal por Eikenella corrodens / Neonatal sepsis due to Eikenella corrodens

No disponible