Acinetobacter baumannii-calcoaceticus complex is the most commonly identified species in the genus Acinetobacter and it accounts for a large percentage of nosocomial infections, including bacteremia, ...pneumonia, and infections of the skin and urinary tract. A few key clones of A. baumannii-calcoaceticus are currently responsible for the dissemination of these organisms worldwide. Unfortunately, multidrug resistance is a common trait among these clones due to their unrivalled adaptive nature. A. baumannii-calcoaceticus isolates can accumulate resistance traits by a plethora of mechanisms, including horizontal gene transfer, natural transformation, acquisition of mutations, and mobilization of genetic elements that modulate expression of intrinsic and acquired genes.
In a systematic review of 109 studies reporting bloodstream infections in hospitalized patients from LMICs, several WHO critical and high priority pathogens were associated with increased mortality, ...length of hospital stay and admission to intensive care units (ICU), and cost 12. To gain a better understanding of the relationship between treatment duration and prevalence of colonization with antimicrobial resistant bacteria in hospitalized patients, Yin Mo and co-workers applied a model to assess how changing duration of antibiotic treatment would affect the risk of resistance colonization at both individual and population levels 14. The authors concluded that shortening antibiotic treatment duration may increase or decrease colonization by resistant bacteria, dependent upon individual and combined bacterial and antibiotic characteristics 14. Using a novel mathematical modeling approach, David Smith and colleagues reported that surges in COVID-19 cases fostered conditions favorable for bacterial transmission, on average resulting in a 14% increase in colonization and a 10% increase in rates of AMR 15.
Abstract
Background
Acinetobacter calcoaceticus–A. baumannii (Acb) complex and Stenotrophomonas maltophilia represent frequent causes of hospital-acquired infections. We evaluated the frequency and ...resistance rates of Acb complex and S. maltophilia isolates from medical centers enrolled in the SENTRY Program.
Methods
A total of 13 752 Acb complex and 6467 S. maltophilia isolates were forwarded to a monitoring laboratory by 259 participating sites from the Asia-Pacific region, Latin America, Europe, and North America between 1997 and 2016. Confirmation of species identification and antimicrobial susceptibility testing were performed using conventional methods and/or matrix-assisted laser desorption ionization–time of flight mass spectrometry and the broth microdilution method, respectively. Antimicrobial susceptibility results were interpreted by CLSI and EUCAST 2018 criteria.
Results
Acb complex and S. maltophilia were most frequently isolated from patients hospitalized with pneumonia (42.9% and 55.8%, respectively) and bloodstream infections (37.3% and 33.8%, respectively). Colistin and minocycline were the most active agents against Acb complex (colistin MIC50/90, ≤0.5/2 mg/L; 95.9% susceptible) and S. maltophilia (minocycline MIC50/90, ≤1/2 mg/L; 99.5% susceptible) isolates, respectively. Important temporal decreases in susceptibility rates among Acb complex isolates were observed for all antimicrobial agents in all regions. Rates of extensively drug-resistant Acb complex rates were highest in Europe (66.4%), followed by Latin America (61.5%), Asia-Pacific (56.9%), and North America (38.8%). Among S. maltophilia isolates, overall trimethoprim-sulfamethoxazole (TMP-SMX) susceptibility rates decreased from 97.2% in 2001–2004 to 95.7% in 2013–2016, but varied according to the geographic region.
Conclusions
We observed important reductions of susceptibility rates to all antimicrobial agents among Acb complex isolates obtained from all geographic regions. In contrast, resistance rates to TMP-SMX among S. maltophilia isolates remained low and relatively stable during the study period.
Bryconops Kner, 1858, includes two well defined subgenera based on morphological evidence, with each containing at least one species (B. (Bryconops) caudomaculatus and B. (Creatochanes) melanurus) ...with a very wide distribution, within which regional populations present color variations. To test if phenotypic variation is related to cladogenetic events, we performed tests for phylogenetic independence and determined the strength of convergence for color characters in relation to water type, as the variation between clear, black and white waters is considered to be one of the major driving forces in the evolution of Amazonian fishes. Color characters for fins above the median line of the body were generally found to be independent from phylogeny and the Wheatsheaf test strongly supports convergence of the dorsal fin color between populations of species in the same type of water, with a similar trend suggested for the color of the dorsal lobe of the caudal fin. This means that simple color characters cannot necessarily be relied upon for taxonomic revisions of the genus as local phenotypic variants may represent environmentally determined plasticity or convergent evolution. Further studies are required to determine the validity of these characters.
Abstract This study updates the frequency and resistance rates of Gram-negative bacilli isolated from Latin American medical centers enrolled in the SENTRY Antimicrobial Surveillance Program. A total ...of 12,811 bacterial organisms, including 5704 Gram-negative bacilli (44.5%), were consecutively collected (1 per patient) between January 2008 and December 2010 from 10 Latin American medical centers located in Argentina, Brazil, Chile, and Mexico. Antimicrobial susceptibility testing was performed and interpreted by the Clinical and Laboratory Standards Institute broth microdilution method at a central laboratory. All Gram-negative organisms with reduced susceptibility to imipenem or meropenem (MIC, ≥ 2 μg/mL) were screened for carbapenemase production by the modified Hodge test and by polymerase chain reaction. ESBL rates were 18.1%, 12.8%, 23.8%, and 48.4% among Escherichia coli and 60.4%, 49.9%, 59.2%, and 33.3% among Klebsiella spp. from Argentina, Brazil, Chile, and Mexico, respectively. Meropenem-nonsusceptible Klebsiella spp. rate was highest in Brazil (11.1%), followed by Argentina (8.2%), Chile (5.0%), and Mexico (0.8%). Klebsiella pneumoniae carbapenemase (KPC)–producing K. pneumoniae was not detected in 2008, but emerged in 2009 (10 strains) and increased significantly in 2010 (44; P < 0.0001). blaKPC-2 was detected in 54 (65.9%) of 85 carbapenem-nonsusceptible K. pneumoniae. Meropenem-nonsusceptible P. aeruginosa was observed in 53.8%, 46.7%, 33.3%, and 28.8% of strains from Argentina, Brazil, Chile, and Mexico, respectively. Imipenem-resistant Acinetobacter spp. rates increased from 6.4%, 12.6%, and 0.0% in the 1997–1999 period to 84.9%, 71.4%, and 50.0% in 2008–2010 in Argentina, Brazil, and Chile, respectively. Oxacillinase (OXA)-producing Acinetobacter spp. was documented in Argentina (OXA-23 and -24), Brazil (OXA-23), Chile (OXA-58), and Mexico (OXA-24). Only colistin showed > 77% overall coverage against the 5 most frequently isolated Gram-negative bacilli from Latin American Medical centers participating in the SENTRY Program.
The rapid detection of KPC-producing Enterobacteriaceae by microbiology laboratories has been required for infectious control programs. Herein we evaluated the performance of a novel ...immunochromatographic test for detecting KPC-2-, KPC-3-, KPC-4-, KPC-6-, KPC-7-, KPC-8-, and KPC-11-producing isolates and the influence of different growth media on the test performance.
•Rapid detection of KPC-producing isolates is still a demanding issue on clinical practice.•A rapid immunochromatographic test was evaluated to detect different variants of KPC.•KPC-6, KPC-7, KPC-8 and KPC-11 variants were evaluated for the first time.•An enhancing on bacterial inoculum was proposed to detect all KPC variants tested.•No influence of commonly bacterial growth medium used on routine microbiology was observed.
Objectives
To comparatively evaluate the antimicrobial activities of colistin and polymyxin B with those of other antimicrobials against a worldwide collection of 40 625 Gram-negative bacilli.
...Methods
Antimicrobial susceptibility testing was performed and interpreted using the CLSI broth microdilution method except for colistin against Enterobacteriaceae.
Results
The polymyxins showed potent in vitro activities (MIC90, ≤0.5-1 mg/L) against this large collection of clinical isolates, with very low resistance rates (<0.1%-1.5%). Resistance to the polymyxins remained stable among organisms tested except for Klebsiella spp. isolates collected from the Asia-Pacific and Latin American regions, where a trend towards greater resistance was observed (P ≤ 0.05). In addition, an important reduction in imipenem susceptibility among Acinetobacter spp. and Klebsiella spp. was demonstrated in most geographical regions.
Conclusions
Although the polymyxins showed excellent in vitro activity against the vast majority of Gram-negative bacilli evaluated, a trend to greater resistance was observed in the Asia-Pacific and Latin American regions. Therefore, the clinical use of polymyxins must be cautious and surveillance monitored.
Carbapenemase-producing Klebsiella pneumoniae has become a global priority, not least in low- and middle-income countries. Here, we report the emergence and clinical impact of a novel Klebsiella ...pneumoniae carbapenemase-producing K. pneumoniae (KPC-KP) sequence type (ST) 16 clone in a clonal complex (CC) 258-endemic setting.
In a teaching Brazilian hospital, a retrospective cohort of adult KPC-KP bloodstream infection (BSI) cases (January 2014 to December 2016) was established to study the molecular epidemiology and its impact on outcome (30-day all-cause mortality). KPC-KP isolates underwent multilocus sequence typing. Survival analysis between ST/CC groups and risk factors for fatal outcome (logistic regression) were evaluated. Representative isolates underwent whole-genome sequencing and had their virulence tested in a Galleria larvae model.
One hundred sixty-five unique KPC-KP BSI cases were identified. CC258 was predominant (66%), followed by ST16 (12%). The overall 30-day mortality rate was 60%; in contrast, 95% of ST16 cases were fatal. Patients' severity scores were high and baseline clinical variables were not statistically different across STs. In multivariate analysis, ST16 (odds ratio OR, 21.4; 95% confidence interval CI, 2.3-202.8; P = .008) and septic shock (OR, 11.9; 95% CI, 4.2-34.1; P < .001) were independent risk factors for fatal outcome. The ST16 clone carried up to 14 resistance genes, including blaKPC-2 in an IncFIBpQIL plasmid, KL51 capsule, and yersiniabactin virulence determinants. The ST16 clone was highly pathogenic in the larvae model.
Mortality rates were high in this KPC-KP BSI cohort, where CC258 is endemic. An emerging ST16 clone was associated with high mortality. Our results suggest that even in endemic settings, highly virulent clones can rapidly emerge demanding constant monitoring.
Abstract
Objectives
To assess the global and regional distribution of ESBLs in Enterobacterales and carbapenemases in Enterobacterales and Pseudomonas aeruginosa.
Methods
Antimicrobial susceptibility ...of isolates collected from ATLAS (2017–2019) was determined per CLSI guidelines. Enterobacterales exhibiting meropenem MICs ≥2 mg/L and/or ceftazidime/avibactam and/or aztreonam/avibactam MICs ≥16 mg/L, Escherichia coli and Klebsiella pneumoniae with aztreonam and/or ceftazidime MICs ≥2 mg/L, and P. aeruginosa with meropenem MICs ≥4 mg/L were screened for β-lactamases by PCR and sequencing.
Results
Globally, ESBL-positive E. coli (23.7%, 4750/20047) and K. pneumoniae (35.1%, 6055/17229) carried predominantly the CTX-M-15 variant (E. coli: 53.9%; K. pneumoniae: 80.0%) with highest incidence in Africa/Middle East (AfME). Among carbapenem-resistant (CR) E. coli (1.1%, 217/20047) and Enterobacter cloacae (3.8%, 259/6866), NDMs were predominant (E. coli in AfME: 62.5%; E. cloacae in Asia Pacific: 59.7%). CR K. pneumoniae (13.3%, 2299/17 229) and P. aeruginosa (20.3%, 4187/20 643) carried predominantly KPC (30.9%) and VIM (14.7%), respectively, with highest frequency in Latin America. Among ESBL-positive Enterobacterales, susceptibility to ceftazidime/avibactam (>90.0%) and amikacin (>85.0%) was higher than to piperacillin/tazobactam (>45.0%) and ciprofloxacin (>7.4%). In CR Enterobacterales, susceptibility to amikacin (>54.0%) and ceftazidime/avibactam (>31.0%) was higher than to ciprofloxacin (>2.7%) and piperacillin/tazobactam (>0.5%). CR P. aeruginosa similarly demonstrated higher susceptibility to amikacin (63.4%) and ceftazidime/avibactam (61.9%) than to ciprofloxacin (26.2%) and piperacillin/tazobactam (25.3%).
Conclusions
Varied distribution of resistance genotypes across regions among ESBL-positive Enterobacterales and CR Enterobacterales and P. aeruginosa provide crucial insights on major resistance mechanisms and trends observed in recent years. Continued surveillance is warranted for monitoring global dissemination and resistance.
Extra-intestinal pathogenic
(ExPEC) may inhabit the human gut microbiota without causing disease. However, if they reach extra-intestinal sites, common cystitis to bloodstream infections may occur, ...putting patients at risk. To examine the human gut as a source of endogenous infections, we evaluated the
clonal diversity of 18 inpatients' guts and their relationship with strains isolated from urinary tract infection (UTI) in the same hospital. Random amplified polymorphic DNA evaluated the clonal diversity, and the antimicrobial susceptibility was determined by disk diffusion. One isolate of each clone detected was sequenced, and their virulome and resistome were determined. Overall, 177 isolates were screened, among which 32 clones were identified (mean of two clones per patient), with ExPEC strains found in over 75% of the inpatients' guts. Endogenous infection was confirmed in 75% of the cases. ST10, ST59, ST69, ST131, and ST1193 clones and critical mobile drug-resistance encoding genes (
,
,
,
, and
) were identified in the gut of inpatients. The genomic analysis highlighted the diversity of the fecal strains, colonization by lactose-negative
, the high frequency of ExPEC in the gut of inpatients without infections, and the presence of β-lactamase producing
in the gut of inpatients regardless of the previous antibiotics' usage. Considering that we found more than one ExPEC clone in the gut of several inpatients, surveillance of inpatients' fecal pathogens may prevent UTI caused by
in the hospital and dissemination of risk clones.
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