Nosocomial Acinetobacter pneumonia

Abstract

Acinetobacter spp. (A. baumannii is the prevalent genomic species, but others may cause infection) has become an increasingly important cause of nosocomial pneumonia, particularly in mechanically ventilated patients (VAP). This organism has intrinsic resistance to some antimicrobials but easily acquires resistance to many others; Acinetobacter spp. can survive for long periods of time in the environment. All of these characteristics have contributed to protracted outbreaks associated with significant morbidity and mortality. High rates of colonization are found in debilitated hospitalized patients. Infecting or colonizing organisms in nosocomial infections are more likely to be from cross-transmission or from the hospital environment than from endogenous sources. VAP caused by Acinetobacter spp. is emerging as a prominent hospital complication. The incidence of this microorganism varies from site to site, but it is the second commonest aetiological agent among the gram-negative bacteria. Longer periods of hospitalization, longer time on mechanical ventilation and prior use of antibiotics are the recognized factors increasing the risk of VAP due to Acinetobacter spp. Treatment needs to clearly differentiate infection from colonization, and the agents with the most antimicrobial activity are imipenem/cilastatin, amikacin, colistin, ampicillin/sulbactam and tigecycline. Monotherapy can be adequate if the patient does not have significant comorbidities. Infection control procedures have a major role to play in preventing transmission of this microorganism. Emphasis on initial control measures should, however, be on strict isolation of infected or colonized patients to limit dissemination of outbreak strains in the environment. The variety of potential sources of contamination with Acinetobacter spp. in the hospital environment makes control of these outbreaks one of the more difficult challenges. Persistence of Acinetobacter spp. in the environment provides ample opportunities for contamination of patients and staff and may explain continuing long-term outbreaks.

Antimicrobial resistance of bacterial isolates from respiratory care wards in Taiwan: a horizontal surveillance study comparison of the characteristics of nosocomial infection and antimicrobial-resistant bacteria in adult Intensive Care Units and two respiratory care facilities for mechanically ventilated patients at a tertiary care centre in Taiwan

“…However, the prevalence rate of NI, which included both new and transferred NIs [25], was significantly higher in the RCW than the ICU. Longer hospital stays in the RCC and RCW compared with the ICUs were contributing factors to the higher prevalence rates, in agreement with previous reports [5,8]. Since NIs in RCW patients were predominantly caused by endogenous enteric pathogens, we speculated that these enteric organisms may become pathogens due to reduced host defences and the selective pressure from treatment with broad-spectrum antimicrobial agents during prior prolonged hospitalisation [17,18], similar to patients on mechanical ventilation who developed pneumonia [26].…”

“…Nosocomial infections (NIs), defined as infections arising in a health institution following admission and a >48 h period of incubation, are a critical complication in ICUs and PMV-focused venues [5][6][7]. Independent risk factors for NI include absence of infection at admission, length of hospitalisation, age >60 years, mechanical ventilation, diagnosis of trauma and catheterisation [8,9].…”

Emergence of resistance to carbapenems in Acinetobacter baumannii in Europe: clinical impact and therapeutic options

“…Notably, it is often difficult to distinguish in these patients upper airway colonisation from VAP. Amongst the main recognised risk factors for acquisition of VAP due to A. baumannii are long periods of hospitalisation, mechanical ventilation and prior use of antibiotics [3,87]. Nosocomial BSIs due to A. baumannii have been reported to account for 1.3% of all nosocomial BSIs [89], with a prevalence of 1.6% and a crude mortality ranging from 34% to 43.4% for ICU-acquired BSIs [89].…”

“…Nosocomial infections due to A. baumannii may involve any site but they predominate in the respiratory tract, urinary tract and wounds [87]. In most institutions, A. baumannii is an increasingly important cause of nosocomial pneumonia in the ICU, particularly in patients with VAP, representing between 5% and 10% of cases [1,23,88].…”

Implication of Haemodiafiltration Flow Rate on Amikacin Pharmacokinetic Parameters in Critically Ill Patients

“…Aminoglycosides are first-line drugs used in the management of severe Gram-negative infections in critical patients [1-3]. The combination of amikacin with β-lactam antibiotics is one of the recommended first-line alternatives for the initial treatment of patients with septic shock or suspected Pseudomonas aeruginosa infection [4, 5].…”