Multidrug-resistant Acinetobacter septicemia in neonates: A study from a teaching hospital of Northern India

Whole-genome sequencing of two multidrug-resistant acinetobacter baumannii strains isolated from a neonatal intensive care unit in Egypt: a prospective cross-sectional study

BACKGROUND

Acinetobacter baumannii (A. baumannii) is a life-threatening and challenging pathogen. In addition, it accounts for numerous serious infections, particularly among immunocompromised patients. Resistance to nearly all clinically used antibiotics and their ability to spread this resistance is one of the most important concerns related to this bacterium.

OBJECTIVES

This study describes different molecular mechanisms of two multidrug-resistant A. baumannii isolates obtained from endotracheal aspirates collected from the neonatal intensive care unit (NICU), Ain Shams University Hospital, Egypt.

METHODS

Following the identification of two isolates, they were examined for susceptibility to antimicrobial agents. This was followed by multilocus sequence typing as well as whole-genome sequence (WGS). Additionally, a Pathosystems Resources Integration Center (PATRIC) analysis was performed.

RESULTS

Two isolates, Ab119 and Ab123, exhibited resistance to all tested antibiotics except for tigecycline and colistin. The WGS analysis of antimicrobial resistance genes (AMR) indicated that both isolates shared beta-lactam, aminoglycoside, macrolides, and sulfonamide resistance genes. Furthermore, each strain revealed different resistance genes such as blaNDM-1, blaNDM-10, OXA-64, aph (3')-VI, Tet-B in Ab119 strain and blaOXA-68, blaPER-1, blaPER-7, Tet-39 in Ab123 strain. Multiple efflux pump genes were detected. Multilocus sequence typing indicated that both isolates belong to the same sequence type (ST931), which belongs to international clone (IC3). Both isolates exhibited the presence of multiple mobile genetic elements (MGEs), but no plasmid was detected in either of them.

CONCLUSIONS

A low prevalence of the IC3 sequence type was identified among two A. baumannii isolates obtained from the NICU in Egypt, exhibiting a high resistance level. Healthcare workers must have knowledge regarding the prevalence of A. baumannii among different populations in order to administer suitable treatment, improve patient outcomes, and apply effective infection control practices.

Deciphering the impact of Acinetobacter baumannii on human health, and exploration of natural compounds as efflux pump inhibitors to treat multidrug resistance

Acinetobacter baumannii is an ESKAPE pathogen and threatens human health by generating infections with high fatality rates. A. baumannii leads to a spectrum of infections such as skin and wound infections, endocarditis, meningitis pneumonia, septicaemia and urinary tract infections. Recently, strains of A. baumannii have emerged as multidrug-resistant (MDR), meaning they are resistant to at least three different classes of antibiotics. MDR development is primarily intensified by widespread antibiotic misuse and inadequate stewardship. The World Health Organization (WHO) declared A. baumannii a precarious MDR species. A. baumannii maintains the MDR phenotype via a diverse array of antimicrobial metabolite-hydrolysing enzymes, efflux of antibiotics, impermeability and antibiotic target modification, thereby complicating treatment. Hence, a deeper understanding of the resistance mechanisms employed by MDR A. baumannii can give possible approaches to treat antimicrobial resistance. Resistance-nodulation-cell division (RND) efflux pumps have been identified as the key contributors to MDR determinants, owing to their capacity to force a broad spectrum of chemical substances out of the bacterial cell. Though synthetic inhibitors have been reported previously, their efficacy and safety are of debate. As resistance-modifying agents, phytochemicals are ideal choices. These natural compounds could eliminate the bacteria or interact with pathogenicity events and reduce the bacteria's ability to evolve resistance. This review aims to highlight the mechanism behind the multidrug resistance in A. baumannii and elucidate the utility of natural compounds as efflux pump inhibitors to deal with the infections caused by A. baumannii.

Novel sequence type of carbapenem-resistant Acinetobacter pittii ST1451 with enhanced virulence isolated from septicaemic neonates in India

BACKGROUND

The clinical relevance of Acinetobacter pittii is increasing, but reports of this organism causing neonatal sepsis are rare.

OBJECTIVES

To understand the mechanisms of resistance and virulence of A. pittii isolated from neonatal blood belonging to a novel sequence type.

MATERIALS AND METHODS

Antibiotic susceptibility, MLST, WGS, phylogenomic comparison with a global collection of carbapenemase-harbouring A. pittii were done. To study the pathogenic potential of novel A. pittii, in vitro and in vivo assays were carried out.

RESULTS AND DISCUSSION

Two novel multidrug-resistant A. pittii from neonatal blood belonging to a novel sequence type 1451 (ST1451) were isolated. WGS revealed that the isolates were almost similar (147 SNP distant) and harbouring two carbapenem resistance genes blaNDM-1 with upstream ISAba125 and downstream bleMBL along with blaOXA-58 with upstream ISAba3. Other resistance genes included blaADC-25, blaOXA-533, aph(3″)-Ib, aph(3')-VIa, aph(6)-Id, aac(3)-IId, mph(E), msr(E), sul2 and tet(39), different efflux pump genes and amino acid substitutions within GyrA (Ser81Leu) and ParC (Ser84Leu; Glu88Ala) were detected among the isolates. The study genomes were closely related to four strains belonging to ST119. The isolates showed biofilm production, serum resistance, growth under iron limiting condition, surface-associated motility and adherence to host cell. Isolates induced cytokine production in the host cell and showed mice mortality.

DISCUSSION AND CONCLUSIONS

This study is the first report of the presence of blaNDM-1 in A. pittii from India along with another carbapenemase blaOXA-58. Emergence of highly virulent, multidrug-resistant A. pittii with attributes similar to A. baumannii calls for surveillance to identify the novel strains and their pathogenic and resistance potential.

Factors Associated With Culture-proven Neonatal Sepsis and Resistance to First-line Antibiotics in Indonesia

BACKGROUND

Neonatal sepsis is one of the leading causes of neonatal morbidity and mortality in low- and middle-income countries. Blood culture positivity rates and antibiotic resistance pattern of neonatal sepsis differs across various regions. This study aims to identify clinical cofactors associated with blood culture-proven neonatal sepsis and in vitro resistance to first-line antibiotics (ampicillin and gentamicin) from cases originating in a tertiary healthcare center in Surabaya, Indonesia.

METHODS

A retrospective cohort study was conducted from January 2020 to August 2022 by utilizing secondary data collected from standardized electronic medical records. Microbiologic characteristics and associated factors were statistically analyzed using multivariable logistic regression.

RESULTS

Across 266 neonatal sepsis cases, 46.9% were culture-proven and 79.2% of confirmed sepsis were resistant to first-line antibiotics. The most common isolated pathogen is Klebsiella pneumoniae , followed by coagulase-negative Staphylococci , Acinetobacter baumannii and Enterobacter cloacae . Extremely preterm delivery [adjusted odds ratio (aOR): 5.813; 95% confidence interval (CI): 1.70-19.91] and late-onset sepsis (aOR: 9.165; 95% CI: 5.12-16.40) were associated with culture-proven neonatal sepsis. Increased odds of resistance to first-line antibiotics were identified in extremely preterm (<28 weeks) or very-preterm delivery (28 to <32 weeks) (aOR: 50.80; 95% CI: 1.66-1554.21 and aOR: 45.679; 95% CI: 3.22-647.46, respectively), cesarean section (aOR: 4.149; 95% CI: 1.04-16.53) and an absence of antenatal corticosteroid use (aOR: 0.233; 95% CI: 0.07-0.76).

CONCLUSIONS

The association between clinical cofactors with culture-proven sepsis and antibiotic resistance emphasizes the importance for clinicians to adjust empirical antibiotic regimens based on the local antibiogram and resource availability.

Risk Factors for 30-Day Mortality in Neonates With Carbapenem-resistant A. baumannii Sepsis

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) sepsis is becoming an extreme threat caused by high-case fatality rates and poor prevention and control in ICUs worldwide. However, the risk of mortality among neonatal CRAB sepsis is still unclear.

METHODS

A retrospective medical records review study, which aimed to identify the risk factors of mortality in neonates with CRAB sepsis (including both bacteremia and/or meningitis) in Thailand from 1996 to 2019. All cases featuring positive blood and cerebrospinal fluid cultures for CRAB were reviewed. A multivariable logistic regression model was analyzed for nonsurvivors and survivors of neonatal CRAB sepsis.

RESULTS

In a 24-year period, 47 of these were identified with CRAB sepsis. The median (interquartile range) gestational age and birth weight were 30 (28-35) weeks and 1500 (933-2482) g, respectively. The 30-day case fatality rate was 55% (26/47). In multivariable analysis, nonsurvivors of neonatal CRAB sepsis were associated with congenital heart disease (adjusted odds ratio [OR] = 1.33; 95% CI 1.06-1.66, P = 0.02), CRIB II score ≥9 (adjusted OR = 1.65; 95% CI: 1.20-2.27, P = 0.004), severe thrombocytopenia (adjusted OR = 1.45; 95% CI: 1.09-1.94, P = 0.02), and septic shock (adjusted OR = 1.62; 95% CI: 1.33-1.99, P <0.001).

CONCLUSION

The risk factors of mortality in neonates with CRAB sepsis are associated with congenital heart disease, CRIB II score ≥9, shock, and severe thrombocytopenia.

Development of Loop-Mediated Isothermal Amplification Assay for Detection of Clinically Significant Members of Acinetobacter calcoaceticus-baumannii Complex and Associated Carbapenem Resistance

Background:Acinetobacter calcoaceticus–baumannii (ACB) complex has emerged as an important nosocomial pathogen and is associated with life-threatening infections, especially among ICU patients, including neonates. Carbapenem resistance in Acinetobacter baumannii has emerged globally and is commonly mediated by bla_OXA-23. Clinically significant infections with carbapenem-resistant Acinetobacter baumannii (CRAB) are a major concern since therapeutic options are limited and associated mortality is high. Early diagnosis of both the pathogen and resistance is important to initiate the optimal therapy and prevent selection of resistance. In the current study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid detection of the ACB complex and carbapenem resistance mediated by bla_OXA-23.

Methodology: Universal LAMP primers were designed for the detection of significant members of the ACB complex and carbapenem resistance targeting the ITS 16S–23S rRNA and bla_OXA-23 gene respectively. The optimal conditions for the LAMP assay were standardized for each primer set using standard ATCC strains. The sensitivity of the LAMP assay was assessed based on the limit of detection (LOD) using different DNA concentrations and colony counts. The specificity of LAMP was determined using the non-ACB complex and non-Acinetobacter species. The results of the LAMP assay were compared with those of polymerase chain reaction (PCR).

Results: The optimal temperature for the LAMP assay was 65°C, and the detection time varied with various primers designed. Using the ITS Ab1 primer, LODs of LAMP and PCR assays were 100 pg/μl and 1 ng/μl of DNA concentration and 10⁴ cfu/ml and 10⁸ cfu/ml of colony count, respectively. The LAMP assay was 10- and 10⁴-fold more sensitive than PCR using DNA concentration and colony count, respectively. The LAMP assay was found to be specific for clinically important ACB complex species.

Significance of the study: The LAMP assay can be applied for early detection of significant species of the ACB complex from clinical samples and their carbapenem-resistant variants. Depending on the emerging pathogen and locally prevalent resistance genes, the LAMP assay can be modified for detection of colonization or infection by various resistant bugs.

Impacts of Multidrug-Resistant Pathogens and Inappropriate Initial Antibiotic Therapy on the Outcomes of Neonates with Ventilator-Associated Pneumonia

It is unknown whether neonatal ventilator-associated pneumonia (VAP) caused by multidrug-resistant (MDR) pathogens and inappropriate initial antibiotic treatment is associated with poor outcomes after adjusting for confounders. Methods: We prospectively observed all neonates with a definite diagnosis of VAP from a tertiary level neonatal intensive care unit (NICU) in Taiwan between October 2017 and March 2020. All clinical features, therapeutic interventions, and outcomes were compared between the MDR–VAP and non-MDR–VAP groups. Multivariate regression analyses were used to investigate independent risk factors for treatment failure. Results: Of 720 neonates who were intubated for more than 2 days, 184 had a total of 245 VAP episodes. The incidence rate of neonatal VAP was 10.1 episodes/per 1000 ventilator days. Ninety-six cases (39.2%) were caused by MDR pathogens. Neonates with MDR–VAP were more likely to receive inadequate initial antibiotic therapy (51.0% versus 4.7%; p < 0.001) and had delayed resolution of clinical symptoms (38.5% versus 25.5%; p = 0.034), although final treatment outcomes were comparable with the non-MDR–VAP group. Inappropriate initial antibiotic treatment was not significantly associated with worse outcomes. The VAP-attributable mortality rate and overall mortality rate of this cohort were 3.7% and 12.0%, respectively. Independent risk factors for treatment failure included presence of concurrent bacteremia (OR 4.83; 95% CI 2.03–11.51; p < 0.001), septic shock (OR 3.06; 95% CI 1.07–8.72; p = 0.037), neonates on high-frequency oscillatory ventilator (OR 4.10; 95% CI 1.70–9.88; p = 0.002), and underlying neurological sequelae (OR 3.35; 95% CI 1.47–7.67; p = 0.004). Conclusions: MDR–VAP accounted for 39.2% of all neonatal VAP in the neonatal intensive care unit (NICU), but neither inappropriate initial antibiotics nor MDR pathogens were associated with treatment failure. Neonatal VAP with concurrent bacteremia, septic shock, and underlying neurological sequelae were independently associated with final worse outcomes.

Considerations and Caveats in Combating ESKAPE Pathogens against Nosocomial Infections

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are among the most common opportunistic pathogens in nosocomial infections. ESKAPE pathogens distinguish themselves from normal ones by developing a high level of antibiotic resistance that involves multiple mechanisms. Contemporary therapeutic strategies which are potential options in combating ESKAPE bacteria need further investigation. Herein, a broad overview of the antimicrobial research on ESKAPE pathogens over the past five years is provided with prospective clinical applications.