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Characteristics of invasive Acinetobacter infection: A multicenter investigation with molecular identification of
Yoshihiko Kiyasu1, Shigemi Hitomi1, Yasunori Funayama2
1Department of Infectious Diseases, University of Tsukuba Hospital, Japan.
Abstract:
We examined microbiological and clinical characteristics of invasive Acinetobacter infection occurring in four hospitals located in the Minami-Ibaraki Area. Glucose-non-fermentative Gram-negative bacilli isolated from the blood and the cerebrospinal fluid in independent cases between 2001 and 2014 were consecutively collected and those possibly to be Acinetobacter species were re-identified using molecular methods. Of 158 strains identified as Acinetobacter species, 155 were classified into 16 officially designated species, including 42 Acinetobacter pittii and 40 Acinetobacter baumannii. Imipenem non-susceptibility was detected only in 4 strains, none of which demonstrated multidrug resistance. Retrospective analyses of 154 cases for which medical records were fully available showed that the most common cause of infection was primary bloodstream infection (134 cases), of which 128 were related to intravascular catheter use. The mortality on day 28 after the onset was independently associated with cerebrovascular disease, moderate to severe renal disease, the Pitt bacteremia score, and infection other than primary bloodstream infection but not with appropriate empiric antimicrobial therapy. Isolation of A. baumannii was significantly associated with septic shock but not with the 28-day mortality. These findings, obtained in a region where drug-resistant Acinetobacter strains were much less prevailing, indicated that non-baumannii Acinetobacter species were common pathogens, that the most predominant cause of invasive Acinetobacter infection was intravascular catheter-related infection, that virulence of A. baumannii might be higher than those of other species but its association with mortality was unclear, and that administration of broad-spectrum antibiotics targeting Acinetobacter species might be deferrable in a certain situation.
Insights
Invasive Acinetobacter infections in the Minami-Ibaraki Area were commonly caused by non-baumannii species, often linked to catheters. While Acinetobacter baumannii showed higher virulence, its impact on mortality was unclear, suggesting targeted antibiotic therapy may be suitable.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Clinical Epidemiology
Background:
- Invasive Acinetobacter infections pose a significant clinical challenge globally.
- Understanding the microbiological and clinical epidemiology of Acinetobacter species is crucial for effective management.
- Previous studies have focused heavily on Acinetobacter baumannii, potentially overlooking other species.
Purpose of the Study:
- To investigate the microbiological and clinical characteristics of invasive Acinetobacter infections in the Minami-Ibaraki Area.
- To identify the predominant Acinetobacter species causing infections and their antimicrobial susceptibility patterns.
- To determine factors associated with mortality in patients with invasive Acinetobacter infections.
Main Methods:
- Molecular methods were used to re-identify Acinetobacter species from blood and cerebrospinal fluid isolates collected between 2001 and 2014.
- 158 Acinetobacter strains were identified, with 155 classified into 16 species, including Acinetobacter pittii and Acinetobacter baumannii.
- Retrospective analysis of 154 patient medical records was performed to assess clinical characteristics and outcomes.
Main Results:
- Non-baumannii Acinetobacter species, particularly A. pittii, were common pathogens, alongside A. baumannii.
- The majority of infections were primary bloodstream infections, predominantly associated with intravascular catheter use.
- Imipenem non-susceptibility was rare, and no multidrug-resistant strains were identified.
- Mortality was associated with comorbidities and infection severity, not empiric antimicrobial therapy.
- A. baumannii isolation correlated with septic shock but not 28-day mortality.
Conclusions:
- Non-baumannii Acinetobacter species are significant pathogens in invasive infections.
- Intravascular catheter-related infections are the leading cause of invasive Acinetobacter disease in this region.
- The virulence of A. baumannii may be higher, but its direct impact on mortality requires further investigation.
- In regions with low prevalence of drug-resistant strains, targeted antibiotic therapy may be appropriate, potentially deferring broad-spectrum agents.
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