Catheter related blood stream infections in the paediatric intensive care unit: A descriptive study

Convergence of Biofilm Formation and Antibiotic Resistance in Acinetobacter baumannii Infection

Acinetobacter baumannii (A. baumannii) is a leading cause of nosocomial infections as this pathogen has certain attributes that facilitate the subversion of natural defenses of the human body. A. baumannii acquires antibiotic resistance determinants easily and can thrive on both biotic and abiotic surfaces. Different resistance mechanisms or determinants, both transmissible and non-transmissible, have aided in this victory over antibiotics. In addition, the propensity to form biofilms (communities of organism attached to a surface) allows the organism to persist in hospitals on various medical surfaces (cardiac valves, artificial joints, catheters, endotracheal tubes, and ventilators) and also evade antibiotics simply by shielding the bacteria and increasing its ability to acquire foreign genetic material through lateral gene transfer. The biofilm formation rate in A. baumannii is higher than in other species. Recent research has shown how A. baumannii biofilm-forming capacity exerts its effect on resistance phenotypes, development of resistome, and dissemination of resistance genes within biofilms by conjugation or transformation, thereby making biofilm a hotspot for genetic exchange. Various genes control the formation of A. baumannii biofilms and a beneficial relationship between biofilm formation and "antimicrobial resistance" (AMR) exists in the organism. This review discusses these various attributes of the organism that act independently or synergistically to cause hospital infections. Evolution of AMR in A. baumannii, resistance mechanisms including both transmissible (hydrolyzing enzymes) and non-transmissible (efflux pumps and chromosomal mutations) are presented. Intrinsic factors [biofilm-associated protein, outer membrane protein A, chaperon-usher pilus, iron uptake mechanism, poly-β-(1, 6)-N-acetyl glucosamine, BfmS/BfmR two-component system, PER-1, quorum sensing] involved in biofilm production, extrinsic factors (surface property, growth temperature, growth medium) associated with the process, the impact of biofilms on high antimicrobial tolerance and regulation of the process, gene transfer within the biofilm, are elaborated. The infections associated with colonization of A. baumannii on medical devices are discussed. Each important device-related infection is dealt with and both adult and pediatric studies are separately mentioned. Furthermore, the strategies of preventing A. baumannii biofilms with antibiotic combinations, quorum sensing quenchers, natural products, efflux pump inhibitors, antimicrobial peptides, nanoparticles, and phage therapy are enumerated.

Clinical profile and outcome of antibiotic lock therapy for bloodstream infections in pediatric hematology/oncology patients in a tertiary care hospital, Karachi, Pakistan

Background

Intravascular catheters are susceptible to infections, thus requiring catheter removal and leading to increased morbidity and costs. Antibiotic lock therapy (ALT) is a therapeutic technique that is used to salvage the catheter. The aim of this study was to evaluate the outcome of antibiotic lock therapy in bloodstream infections in pediatric hematology/oncology patients in a tertiary care hospital, Karachi.

Methods

A retrospective review was performed from January 2013 to December 2017 of pediatric hematology/oncology patients with bloodstream infections and who received ALT at Aga Khan University Hospital. All cases of polymicrobial infections, catheter removal, or malfunction before the completion of ALT were excluded. Descriptive analysis was carried out using SPSS version 20.

Results

A total of nine hematology/oncology patients were eligible. The catheter was salvaged in 7/9 (77.8%) children, and in 2/9 (22.2%) cases, catheter was removed because of persistent bacteremia. The most common organism isolated was Staphylococcus non-aureus species (33.3%). Relapse with a similar pathogen occurred in 2 (22.2%) patients and 2 (22.2%) of them developed an exit-site infection.

Conclusion

In our experience, in almost two thirds of the cases, the catheter was salvaged, but disappointingly, relapses were high when the infection was due to Staphylococcus spp. Although this is a small study, our results show that ALT can be a potential safe adjunctive strategy to treat catheter-related bloodstream infections (CRBSI). However, we need larger prospective studies to test the safety and efficacy of ALT to develop specific ALT recommendations and guidelines particularly in children.

Umbilical catheters as vectors for generalized bacterial infection in premature infants regardless of antibiotic use

Introduction. Umbilical catheterization offers unique vascular access that is only possible in the neonatal setting due to unobstructed umbilical vessels from foetal circulation. With the cut of the umbilical cord, two arteries and a vein are dissected, allowing quick and painless catheterization of the neonate. Unfortunately, keeping the umbilical access sterile is challenging due to its mobility and necrosis of the umbilical stump, which makes it a perfect model for vessel catheter colonization analysis.Aim. The aim of this study was to evaluate bacterial colonization of the umbilical catheter, with a focus on the difference between various sections of the catheter, the duration of catheterization, patient status and gestational age.Methodology. We performed bacterial cultures for 44 umbilical catheters, analysing the superficial and deep parts of the catheter separately, and revealed colonization in one-third of cases.Results. One hundred per cent of the colonization occurred in preterm infants, with a shift towards extreme prematurity. The catheters were mainly colonized by coagulase-negative staphylococci. The majority of catheters presented with superficial colonization dominance, and there were no cases of deep colonization. The bacterial strains and their resistance were consistent between the catheter's proximal and distal parts, as well as positive blood cultures. The patients with the most intense bacterial catheter colonization presented with sepsis around removal time or a couple of days later, especially if they were extremely premature and exhibited very low birth weight. Catheterization time did not play a major role.Conclusion. Umbilical catheters are vectors for skin microflora transmission to the bloodstream via biofilm formation, regardless of antibiotic use and the duration of catheterization, especially in preterm neonates.