Blood Culture Isolates Research Articles

Distribution of the invasive pathogenic isolates in blood culture with their antimicrobial susceptibility pattern in a diagnostic laboratory in Karachi.

To determine the frequent bacterial pathogens causing blood stream infections in various age brackets, and to discover their antibiotic susceptibility pattern. The retrospective, descriptive, observational, cross-sectional study was conducted at the microbiology laboratory of Patel Hospital, Karachi, and comprised positive blood culture bacterial isolates analysed between July 1, 2018, and June 30, 2019. Standard microbiological techniques were employed for the identification and antimicrobial susceptibility testing. Data was analysed using SPSS 20. Of the 3450 specimen, 1243(36%) were positive; 668(53.7%) from male and 575(46.3%) from female subjects, and 771(62%) were gram-positive whereas 472(38%).were gram-negative. Salmonella typhi was the most common pathogen 139(11.1) among gram-negative organisms, followed by Acinetobacter species 103(8.2%), Escherichia coli 96(7.7%) and Klebsiella species 42(3.4%). Among gram-positive bacteria, the predominant isolates were staphylococcus epidermidis 650(52%), staphylococcus aureus 67(5.4%) and enterococci 28(2.3%). Linezolid (99.8%), vancomycin (99%) and chloramphenicol (69%) were found to be the most sensitive antibiotics among gram-positive cocci. Meropenem (60%), amikacin (46%) and gentamicin (40%) were the most sensitive antibiotics for multidrug resistant gram-negative bacteria. The identification of frequent bacterial pathogens in blood cultures of patients may guide clinicians in proper empirical selection of antibiotics in patients with bacteraemia.

Assessment of the antifungal susceptibility profile and virulence factors of non-albicans candida species obtained from the infection of the bloodstream

Background: Earlier the fungal infection spectrum was considered to be only restricted to mucocutaneous and cutaneous tissues. However, this consideration has now changed. The threatening rise in the incidence of invasive mycosis is seen recently. Despite advancements in diagnostic and therapeutic modalities, high mortality rates are linked to invasive mycosis. The most common cause of bloodstream infections is Candida spp. Among candida genus, the most pathogenic species is C. Albicans, recent literature data has shown the emergence of treatment-resistant, relatively uncommon, and unusual nonalbicans Candida (NAC) spp. Aim: The present study was conducted to assess the antifungal susceptibility profile and virulence factors of non-Albicans candida species obtained from the infection of the bloodstream. Material and methods: The present study included blood culture isolates of nonalbicans Candida (NAC) spp. which were identified to species level using the standard mycological protocol. This NAC spp. were screened for virulence factors production including biofilm formation, hemolysin, and extracellular hydrolytic enzymes. Ezy MIC strip was used for assessing the antifungal susceptibility profile of these isolates. Results: 100% (n=1) C. rugosa NAC spp. showed hemolysin production. In C. gulliermondii, 50% (n=1) subject showed phospholipase production and biofilm formation each.

P333 Candidemia due to Candida pelliculosa in neonates admitted in SNCUs of district hospitals of Chhattisgarh: first state-wide study from secondary-level health care facilities in Central India

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM ObjectivesTo study the Candida pelliculosa isolates, from the blood culture of neonates admitted to district hospital SNCUs in the state of Chhattisgarh, their antifungal susceptibility pattern, risk factors, and clinical co-relation. Although Candida species remain the leading cause of invasive fungal infections (IFI), there are certain rare species like C. pelliculosa, that can cause fungemia. Various studies reveal that infants, children, and immunocompromised individuals are more susceptible to bloodstream infections of C. pelliculosa. Few cases of fungemia caused by this rare species of Candida have been reported worldwide. We have found a few cases of C. pelliculosa bloodstream infection in neonates admitted to special newborn care units (SNCUs).MethodsThis is an observational study on the Candida isolates from blood cultures of neonates admitted in SNCUs of the state of Chhattisgarh, over a period of 4 years from March 2018 till March 2022. Blood culture isolates of Candida were identified and their AFST was performed on an automated Bacterial ID-AST system by BioMerieux (VITEK -2) and also manually using standard laboratory protocols. Demographic and clinical data of the patients having Candida pelliculosa candidemia were taken from laboratory records.ResultsPaired blood culture samples of total 4997 SNCU neonates were received in the laboratory. Out of these 25% were found positive for bacteria and or Candida spp. Among these positive blood cultures, Candida spp. was isolated in 18.76% patients. Amongst the isolates of Candida, C. pelliculosa was found to be the predominant Candida spp., isolated in 60 neonates, thus comprising of 25.64% of all Candida spp. Further analysis of neonates having C. pelliculosa infection revealed that 40% (24/60) neonates were either low birth weight, very low birth weight (VLBW), or extremely low birth weight (ELBW) babies, 25% cases had respiratory distress, 21.6% neonates were premature and 10% cases had hypoglycemia, as risk factors.Antifungal susceptibility pattern showed 99% isolates of C. pelliculosa as susceptible to amphotericin B, 100% being susceptible to voriconzole, and 95% and 100% isolates were susceptible to fluconazole and flucytosine respectively. More resistance was observed for Echinocandins. Caspofungin was found to be least susceptible in 88.9% of isolates. Various indications for blood culture were also analyzed. Only one neonate, out of 60, succumbed to C. pelliculosa infection.Conclusion Candida pelliculosa is found to be an emerging pathogen responsible for candidemia among neonates in SNCUs, which has shown relatively poor in-vitro susceptibility to Echinocandins. It is of extreme clinical importance that neonates of secondary-level health care facilities should also have access to quality laboratory support in the form of culture and sensitivity, so that pathogen profile and antibiogram data are available from such high-risk units as well, which would prove useful in timely institution of targeted therapy, thereby reducing neonatal mortality.

Trends in Occurrence and Phenotypic Resistance of Coagulase-Negative Staphylococci (CoNS) Found in Human Blood in the Northern Netherlands between 2013 and 2019.

Background: For years, coagulase-negative staphylococci (CoNS) were not considered a cause of bloodstream infections (BSIs) and were often regarded as contamination. However, the association of CoNS with nosocomial infections is increasingly recognized. The identification of more than 40 different CoNS species has been driven by the introduction of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Yet, treatment guidelines consider CoNS as a whole group, despite increasing antibiotic resistance (ABR) in CoNS. This retrospective study provides an in-depth data analysis of CoNS isolates found in human blood culture isolates between 2013 and 2019 in the entire region of the Northern Netherlands. Methods: In total, 10,796 patients were included that were hospitalized in one of the 15 hospitals in the region, leading to 14,992 CoNS isolates for (ABR) data analysis. CoNS accounted for 27.6% of all available 71,632 blood culture isolates. EUCAST Expert rules were applied to correct for errors in antibiotic test results. Results: A total of 27 different CoNS species were found. Major differences were observed in occurrence and ABR profiles. The top five species covered 97.1% of all included isolates: S. epidermidis, S. hominis, S. capitis, S. haemolyticus, and S. warneri. Regarding ABR, methicillin resistance was most frequently detected in S. haemolyticus (72%), S. cohnii (65%), and S. epidermidis (62%). S. epidermidis and S. haemolyticus showed 50–80% resistance to teicoplanin and macrolides while resistance to these agents remained lower than 10% in most other CoNS species. Conclusion: These differences are often neglected in national guideline development, prompting a focus on ‘ABR-safe’ agents such as glycopeptides. In conclusion, this multi-year, full-region approach to extensively assess the trends in both the occurrence and phenotypic resistance of CoNS species could be used for evaluating treatment policies and understanding more about these important but still too often neglected pathogens.

Risk factors for antimicrobial resistance in patients with Escherichia coli bacteraemia related to urinary tract infection

NHS Lothian policy has recently changed to avoid first-line use of trimethoprim for uncomplicated urinary tract infections (UTI) in patients with risk factors for trimethoprim resistance, in line with national guidance. This study aimed to identify risk factors for antimicrobial resistance in Escherichia coli bacteraemia related to UTI. A retrospective cohort study of 687 patients with E.coli bacteraemia related to UTI in NHS Lothian from 01/02/18 to 29/02/20 was undertaken. Demographics and comorbidities were collected from electronic patient records. Community prescribing and microbiology data were collected from the prescribing information system and Apex. Univariate and multivariate analysis was undertaken using RStudio to analyse trimethoprim, gentamicin and multi-drug resistance (MDR). Trimethoprim resistance was present in 282/687(41%) of blood culture isolates. MDR was present in 278/687(40.5%) isolates. Previous urinary trimethoprim resistant E.coli was a significant risk factor for both trimethoprim resistance (OR 9.44, 95%CI 5.83-15.9) and MDR (OR 4.81, 95%CI 3.17-7.43) on multivariate modelling. Trimethoprim prescription (OR 2.10, 95% CI 1.33-3.34) and the number of community antibiotic courses (OR 1.19, 95%CI 1.06-1.35) were additional risk factors for trimethoprim resistance. Multiple independent risk factors were also identified for trimethoprim resistance, MDR and gentamicin resistance. This study showed a high prevalence of trimethoprim resistance and MDR in patients with E.coli bacteraemia related to UTI. This supports the withdrawal of trimethoprim from first-line treatment of UTIs in patients with risk factors for trimethoprim resistance. It has also identified risk factors for MDR in E.coli bacteraemia.

Bacteriological profile and antibiogram of blood culture isolates from bloodstream infections in a rural tertiary hospital in Nigeria.

BackgroundBloodstream infections (BSIs) are a cause of significant morbidity and mortality requiring urgent antibiotic treatment. However, there is widespread antibiotic-resistance from the bacterial causes, necessitating regular surveillance for drug-resistant bacteria and their antibiograms.ObjectiveThis study isolated and identified various bacterial causes of BSIs, determined their antibiotic susceptibility patterns, and determined the best empirical treatment for cases of BSI in the setting.MethodsA cross-sectional study was carried out at the Federal Teaching Hospital, Ido-Ekiti, Nigeria between June 2020 and February 2021 on 177 blood culture samples from cases of BSI. Identification of isolated bacteria and antibiotic susceptibility testing of the isolates were carried out following the standard protocol.ResultsCulture positivity in this study was 19.2%. No significant difference was seen in culture positivity between male and female participants (p = 0.97). Gram-negative enteric bacteria were predominantly isolated (67.6%), including Escherichia coli (29.4%) and Klebsiella aerogenes (20.6%). Staphylococcus aureus was the most common Gram-positive bacterium isolated (23.5%). Three (37.5%) S. aureus isolates were methicillin-resistant. All isolates were sensitive to meropenem, and 97.1% were sensitive to imipenem; other sensitivity patterns were: ceftazidime (85.3%), ciprofloxacin (79.4%), ofloxacin (79.4%), and gentamicin (76.5%). There was low sensitivity to ampicillin (32.4%) and cotrimoxazole (38.2%). All Gram-positive isolates, including methicillin-resistant S. aureus, were sensitive to vancomycin.ConclusionRegular surveillance of isolate sensitivity patterns, formulation of hospital antibiotic policies based on existing data and compliance with treatment guidelines will promote rational antibiotic use and reduce resistance among bacteria.

Apramycin susceptibility of multidrug-resistant Gram-negative blood culture isolates in five countries in Southeast Asia

IntroductionBloodstream infections (BSIs) are a leading cause of sepsis, which is a life-threatening condition that significantly contributes to the mortality of bacterial infections. Aminoglycoside antibiotics such as gentamicin or amikacin are essential medicines in the treatment of BSIs, but their clinical efficacy is increasingly being compromised by antimicrobial resistance. The aminoglycoside apramycin has demonstrated preclinical efficacy against aminoglycoside-resistant and multidrug-resistant (MDR) Gram-negative bacilli (GNB) and is currently in clinical development for the treatment of critical systemic infections. MethodsThis study collected a panel of 470 MDR GNB isolates from healthcare facilities in Cambodia, Laos, Singapore, Thailand and Vietnam for a multicentre assessment of their antimicrobial susceptibility to apramycin in comparison with other aminoglycosides and colistin by broth microdilution assays. ResultsApramycin and amikacin MICs ≤ 16 µg/mL were found for 462 (98.3%) and 408 (86.8%) GNB isolates, respectively. Susceptibility to gentamicin and tobramycin (MIC ≤ 4 µg/mL) was significantly lower at 122 (26.0%) and 101 (21.5%) susceptible isolates, respectively. Of note, all carbapenem and third-generation cephalosporin-resistant Enterobacterales, all Acinetobacter baumannii and all Pseudomonas aeruginosa isolates tested in this study appeared to be susceptible to apramycin. Of the 65 colistin-resistant isolates tested, four (6.2%) had an apramycin MIC > 16 µg/mL. ConclusionApramycin demonstrated best-in-class activity against a panel of GNB isolates with resistances to other aminoglycosides, carbapenems, third-generation cephalosporins and colistin, warranting continued consideration of apramycin as a drug candidate for the treatment of MDR BSIs.

Epidemiology and Sensitivity Profile of Blood Culture Isolates at The Pediatric University Hospital of Bangui

Background: Bacteremia are serious and dreaded diseases, due to their high associated mortality, for which blood culture is the key examination for establishing the diagnosis. Little is known about the epidemiology of sepsis in the Central African Republic (CAR). Objective: To determine the epidemiology and antibiotic susceptibility profile of bacteria isolated from blood cultures in the CHUPB, in order to optimize the probabilistic antibiotic therapy used in first line. Methodology: This was a cross-sectional study conducted at the University Hospital of Bangui (CHUPB) over a period of 12 months (January 1 to December 31, 2021), covering all bacteria isolated from blood cultures taken from children hospitalized in intensive care and neonatal intensive care units. The data were analyzed with the STATA version 14 software. The Chisquare test and ANOVA test were used to compare proportions at the p<0.05 threshold. Results: Out of four hundred and fifty-five blood cultures performed during the 12 months, the positivity rate was 13.17% (n=56/425). The neonatal intensive care unit had a positivity rate of 75% (n=42) versus 25% (n=14) for the intensive care unit. The mean age of the blood culture positive children was 19 days (3 days to 15 years) and the sex ratio was 1.94. Among the 56 isolates, a high prevalence of gram-negative bacilli 98.21% (n=55) was noted. The most frequently isolated species were Klebsiella pneumoniae 75% (n=42) and Escherichia coli 19.64% (n=11). Staphylococcus aureus 1.78%(n=1) was the only Gram-positive cocci isolated. Enterobacteriaceae were multi-resistant to empirical antibiotics at CHUPB. Only Tigecycline and Amikacin were still more than 90% sensitive to Klebsiella pneumoniae. Escherichia coli had a sensitivity greater than 80% for Ertapenem, Imipenem and chloramphenicol. Conclusion: This study, which was the first at the CHUPB, underlined the importance of regular monitoring of blood culture isolates, while determining antibiotic sensitivities in order to better guide the probabilistic antibiotic therapy of bacteremia. Key words : Blood cultures - epidemiology - isolates - CHUPB.

Genomic Study on Blood Culture Isolates From Patients With Staphylococcus Infection-associated Glomerulonephritis

IntroductionStaphylococcus infection-associated glomerulonephritis (SAGN), is an autoimmune sequela of infection affecting a subset of infected patients without specific predictive factors, frequently presenting with acute nephritic syndrome and propensity for chronic kidney disease. We performed a comparative genotypic and phenotypic analysis of S. aureus isolates from patients that did and those that did not develop SAGN.MethodsWe had 22 culture-proven cases of SAGN from Ohio State University Wexner Medical Center (OSUWMC) from 2004 to 2016, 9 of 22 being blood cultures, with archived isolates. These, along with blood culture isolates from 12 patients with no clinical evidence of SAGN (between ages 40 to 80 years) over the same period were used for genotyping. For host demographic comparison, we used all available SAGN cases (n = 85, including those with positive cultures other than blood; and patients with kidney biopsies received from referring hospitals) and all OSUWMC patients with positive Staphylococcus cultures without glomerulonephritis (GN) (n = 23,496).ResultsMultiple sequence types (STs) suggesting strain diversity was seen in the GN isolates with mainly clonal complexes (CC) 5 and 59. Mutations in the agr operon were identified in significantly higher number of the GN isolates (83%) than non-GN isolates (16%). Significant differences in β-hemolysis and biofilm formation was also observed between the groups.ConclusionThe functionality of these agr mutants remains to be seen, but the presently known effects of reduced agr function, namely increased surface adhesins, biofilm formation, and persistent bacteremia could be important microbial factors predisposing to SAGN and testing for them early during infection could help to predict its development.

Pseudomonas putida bacteremia in pediatric patients: A case series study

IntroductionBacteria of the genus Pseudomonas act as opportunistic pathogens. Pseudomonas putida has been considered a pathogen of low virulence and susceptible to multiple antibiotics, but in recent years resistant strains have emerged. The objective of this study is to describe the clinical characteristics, evolution and antibiotic resistance of P. putida bacteremia documented in pediatric hospitalized patients. MethodsRetrospective cases series. Pediatric patients admitted to the Prof. Dr. Juan P. Garrahan Hospital of Buenos Aires City, Argentina, with isolation in blood cultures of P. putida were included, between August 2015 and August 2020. ResultsSample consisting of 13 patients. Median age: 81 months (IQR 15−163). Ten of the patients were immunocompromised (77%), 11 (85%) had a central venous catheter, 2 (15%) received transfusions prior to the episode of bacteremia, and 6 (46%) had had an invasive procedure within the previous 30 days. Three patients (23%) presented bacteremia secondary to clinical focus and 10 (77%) had central venous catheter-associated bacteremia. All presented fever, 62% (8) evolved with sepsis and 15% (2) with septic shock. Two patients required admission to the intensive care unit (15%), and in 7 (54%) the central venous catheter was removed. None died. The median days of treatment was 14 (IQR 10−14). Resistance to carbapenems was 30%. ConclusionAll children had underlying comorbidities, most of them immunocompromised. Catheter-associated infection predominated. The sensitivity to antibiotics was variable. Given the emergence of multi-resistant strains, it is essential to know the local epidemiology.

Community-acquired bacteraemia by Klebsiella pneumoniae producing KPC-3 and resistant to ceftazidime/avibactam

To describe the clinical and microbiological features of a case of community-acquired infection by KPC-producing K. pneumoniae (KPCKP) resistant to ceftazidime/avibactam (CAZ-AVI). Identification of microorganisms was performed with MALDI Biotyper CA System (BrukerDaltonics, Madrid, Spain). Antimicrobial susceptibility testing was performed using Sensitre EURGNCOL panels (Thermo Fisher Scientific, Madrid, Spain) and gradient strips (Etest, bioMérieux, Madrid, Spain) in the case of CAZ-AVI, using EUCAST breakpoints for interpretation. Whole genome sequencing of blood culture and rectal swab isolates was performed using the Illumina NovaSeq 6000 sequencing system, with 2×150-bp paired-end reads (Illumina, Inc.). Blood culture and rectal swab KPCKP isolates were resistant to carbapenems and to CAZ-AVI. The blood culture isolate showed susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX), but the rectal swab culture isolate was resistant to this antibiotic. Both isolates belonged to clonal lineage ST512, harboured a single copy of blaKPC-3 gene, and showed 16 single nucleotide polymorphisms (SNP) between them and 38 SNPs with regard to the first KPC-3 producing K. pneumoniae isolated in our hospital in an initial outbreak in 2012. Genome-wide resistome analysis revealed the presence of a IncFIB(K) plasmid harbouring sul1 and dfrA12 genes only in the rectal swab culture isolate, which may explain its resistance to TMP-SMX. Resistance to ceftazidime-avibactam is an emerging nosocomial problem. This case shows that CAZ-AVI-resistant KPCKP strains may disseminate into the community and cause serious infections.

Cryptogenic hepatitis patients have a higher Bartonella sp.-DNA detection in blood and skin samples than patients with non-viral hepatitis of known cause.

BackgroundThis study aimed to assess the prevalence of Bartonella sp.-DNA detection in blood and skin samples from patients with non-viral end-stage liver disease awaiting liver transplantation.Methodology/Principal findingsBlood samples and healthy skin fragments from 50 patients were tested using microbiological and molecular methods. Fifteen patients had cryptogenic hepatitis (CH) and 35 had alcoholic, drug-induced or autoimmune liver disease. DNA was extracted from whole blood and liquid culture samples, isolates, and skin fragments. Thirteen of the 50 patients (26%) had Bartonella henselae DNA detection in their blood (9/50) and/or skin (5/50) samples. Colonies were isolated in 3/50 (6%) and infection was detected in 7/50 (14%) of the 50 patients. B. henselae-DNA detection was more prevalent in patients with CH than in other patients (p = 0.040). Of 39 patients followed-up for at least two years, a higher mortality rate was observed among patients with CH infected with B. henselae (p = 0.039).Conclusions/SignificanceFurther studies assessing the role of B. henselae infection in the pathogenesis of hepatitis patients must be urgently conducted.

Retrospective data analysis for definition of multidrug resistance in gram-negative bacteria - a consensus proposal.

The main objective of this study was to propose a common definition of multidrug-resistant gram-negative organisms (GN-MDRO), which may be used for epidemiological surveillance and benchmarking. In this retrospective data analysis, we used interpreted qualitative susceptibility data (SIR) from blood culture isolates of different gram-negative microorganisms from the ANRESIS database from 2017-2021. We first analysed testing algorithms used by different Swiss laboratories and investigated cross-resistance patterns within antibiotic groups. Comparing these data with existing international definitions, we developed two different GN-MDRO definitions, an extended one for surveillance purposes (ANRESIS-extended) and a more stringent one for clinical purposes, aimed primarily at the identification of difficult-to-treat GN-MDRO (ANRESIS-restricted). Using these novel algorithms, the rates of invasive GN-MDRO identified in our national dataset were compared with international and national definitions: the European Centre for Disease Prevention and Control (ECDC) definition, the Commission for Hospital Hygiene and Infection (KRINKO) definition and the definition proposed by the University Hospital Zurich. SIR data of a total of 41,785 Enterobacterales, 2,919 , and 419 spp. isolates were used for the analyses. Five antibiotic categories were used for our MDRO definition: aminoglycosides, piperacillin-tazobactam, third- and fourth-generation cephalosporins, carbapenems and fluoroquinolones. Large differences were found between the testing algorithms of the different laboratories. Cross-resistance analysis within an antibiotic group revealed that the substance most likely to be effective against a particular gram-negative bacterium was not preferentially tested (e.g. amikacin for the aminoglycosides). For all bacterial species tested, the highest rates of multidrug-resistant isolates were found using the ECDC-MDR definition, followed by the ANRESIS-extended definition. The number of MDR-Enterobacterales identified using the ANRESIS-restricted definition (n = 627) was comparable to those identified using the KRINKO (n = 622) and UHZ definitions (n = 437). However, the isolates classified as MDR-Enterobacterales according to the KRINKO, UHZ and ANRESIS-restricted definitions (total n = 870) differed considerably. Only 242 of the isolates (27.8%) were uniformly classified as MDRO according to the KRINKO, UHZ and ANRESIS-restricted definitions. Comparable findings were made for Klebsiella spp. and Pseudomonas aeruginosa. The application of different MDRO definitions leads to significant differences in not only MDRO rates but also the isolates that are eventually classified as MDRO. Therefore, defining a nationwide MDRO algorithm is crucial if data are compared between hospitals. The definition of a minimal antibiotic susceptibility testing panel would improve comparability further.

Global Distribution of O Serotypes and Antibiotic Resistance in Extraintestinal Pathogenic Escherichia coli Collected From the Blood of Patients With Bacteremia Across Multiple Surveillance Studies.

Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause of bacteremia worldwide, with older populations having increased risk of invasive bacterial disease. Increasing resistance to first-line antibiotics and emergence of multidrug-resistant (MDR) strains represent major treatment challenges. ExPEC O serotypes are key targets for potential multivalent conjugate vaccine development. Therefore, we evaluated the O serotype distribution and antibiotic resistance profiles of ExPEC strains causing bloodstream infections across 4 regions. Blood culture isolates from patients aged ≥60 years collected during 5 retrospective E. coli surveillance studies in Europe, North America, Asia-Pacific, and South America (2011-2017) were analyzed. Isolates were O serotyped by agglutination; O genotyping was performed for nontypeable isolates. Antimicrobial susceptibility testing was also conducted. Among 3217 ExPEC blood culture isolates, the most ubiquitous O serotype was O25 (n = 737 [22.9%]), followed by O2, O6, O1, O75, O15, O8, O16, O4, O18, O77 group, O153, O9, O101/O162, O86, and O13 (prevalence of ≥1%). The prevalence of these O serotypes was generally consistent across regions, apart from South America; together, these 16 O serotypes represented 77.6% of all ExPEC bacteremia isolates analyzed. The overall MDR frequency was 10.7%, with limited variation between regions. Within the MDR subset (n = 345), O25 showed a dominant prevalence of 63.2% (n = 218). Predominant O serotypes among ExPEC bacteremia isolates are widespread across different regions. O25 was the most prevalent O serotype overall and particularly dominant among MDR isolates. These findings may inform the design of multivalent conjugate vaccines that can target the predominant O serotypes associated with invasive ExPEC disease in older adults.

SPUTUM MICROBIAL PROFILE AND CLINICAL FEATURES OF PATIENTS WITH NEGATIVE GENEXPERT AND AFB IN MANILA, PHILIPPINES: A PILOT RETROSPECTIVE ANALYTICAL STUDY

TYPE: Abstract TOPIC: Chest Infections PURPOSE: In 2019, the Philippines was amongst the seven countries accounting for the greatest burden (90%) of tuberculosis (TB) in the world. We sought to investigate the presence of other potentially pathogenic organisms and their clinical features in archived sputum samples from acutely unwell patients clinically diagnosed with TB and admitted to a TB ward in Manila and not on treatment. These patients however, had a negative Xpert® MTB/Rif assay and Acid-Fast Bacilli (AFB). METHODS: A pilot retrospective molecular analytical cross-sectional study on 82 sputa samples was carried out. DNA was extracted. Positive controls prepared from blood culture isolates were extracted using the same DNA Quiagen kit following manufacturers protocol. Three multiplex Polymerase chain reactions (PCR) were designed for Hemophilus influenzae, Moraxella catarrhalis), Streptococcus pneumoniae, mycoplasma pneumoniae, Legionella pneumoniae, Chlamydia pneumoniae, and Burkholderia pseudomallei, thailandensis. Shimadzu MultiNA Microchip Electrophoresis System was used for DNA analysis. Statistics analysis was done on STATA® 15. RESULTS: The prevalence of bacteria was 74/82(90.24%). Burkholdera pseudomallei 72/82(87.80%) and Hemophilus influenza 22/82(26.83%) were most prevalent. A cough of over 2-week was 51/82(76.12%). X-ray findings consistent with TB was 59/76(86.76%). The odds of a cough of over two weeks and weight loss were about six {OR 5.70(CI: 1.79, 18.09)}, p=0.0008 and four folds {OR 4.44(95%CI:1.56, 12.62)} p=0.0022 respectively greater in those with positive Xpert/AFB compared to those negative. CONCLUSIONS: Other bacterial infections can be found in patients suspected of PTB. A cough of over 2 weeks, fever, chest x-ray lesions, and weight loss can be present in other lung affections/diseases. CLINICAL IMPLICATIONS: diagnostics DISCLOSURE: Nothing to declare. KEYWORD: GeneXpert negative

Multidrug-Resistant Bloodstream Infections in Internal Medicine: Results from a Single-Center Study.

Infections due to multidrug-resistant organisms (MDROs) are expanding globally and are associated with higher mortality rates and hospital-related costs. The objectives of this study were to analyze the trends of MDRO bacteremia and antimicrobial resistance rates in Internal Medicine wards of our hospital and to identify the variables associated with these infections. During a 6-year period (July 1, 2011-June 30, 2017), patients with positive blood culture isolates hospitalized in the Internal Medicine wards in the Santa Croce and Carle Hospital in Cuneo, Italy, were assessed. We performed an analysis taking into consideration the time trends and frequencies of MDRO infections, as well as a case-control study to identify clinical-demographic variables associated with MDRO bacteremias. During the study period a total of 596 blood cultures were performed in 577 patients. The most frequently identified organism was Escherichia coli (33.7%), followed by Staphylococcus aureus (15.6%) and S epidermidis (7.4%). The percentage of resistance to methicillin among S aureus isolates showed a decreasing trend, whereas rates of extended-spectrum β-lactamase-producing Enterobacteriaceae and carbapenemase-producing Klebsiella pneumoniae increased during the study period. Multivariate analysis showed that the nosocomial origin of the infection, hospitalization during the previous 3 months, residence in long-term care facilities, presence of a device, antibiotic exposure during the previous 3 months, and cerebrovascular disease were independently associated with bacteremia by resistant microorganisms. Our analysis reveals a concerning microbiological situation in an Internal Medicine setting, in line with other national and regional data. The risk variables for infection by MDRO identified in our study correspond to those reported in the literature, although studies focused on Internal Medicine settings appear to be limited.

Screening for β-lactam resistance by penicillin G in the Streptococcus anginosus group challenged by rare strains with altered PBPs.

Streptococcus anginosus group (SAG) strains are common pathogens causing abscesses and bacteraemia. They are generally susceptible to β-lactams, which constitute first-line treatment. EUCAST recommends testing penicillin G susceptibility to screen for β-lactam resistance. Isolates categorized as susceptible (negative screening) can be reported as susceptible to aminopenicillins and third-generation cephalosporins. To assess the reliability of penicillin G resistance screening in predicting β-lactam resistance in SAG blood culture isolates, and to investigate isolates for which this test would be unreliable. We determined the susceptibility to penicillin G, amoxicillin and ceftriaxone of 90 SAG blood culture isolates, all with negative penicillin G resistance screening. β-Lactam-resistant strains were sequenced and compared with susceptible reference SAG strains. We detected two isolates displaying β-lactam resistance, especially to third-generation cephalosporins, despite negative screening for penicillin G resistance. For these isolates, amino acid substitutions were identified next to the essential PBP motifs SxxK, SxN and/or KS/TGS/T. Changes in these motifs have been previously linked to β-lactam resistance in Streptococcus pneumoniae. Our study suggests that aminopenicillin and third-generation cephalosporin susceptibility should be determined for SAG strains in the event of severe infection as screening for penicillin G resistance might not be sufficient to detect resistance mechanisms that predominantly affect cephalosporins. The PBP sequencing of resistant SAG strains allowed us to detect amino acid changes potentially linked to β-lactam resistance.

Correlation between Identification of β-Lactamase Resistance Genes and Antimicrobial Susceptibility Profiles in Gram-Negative Bacteria: a Laboratory Data Analysis.

ABSTRACTWe reported the frequency of resistance gene detection in Gram-negative blood culture isolates and correlated these findings with corresponding antibiograms. Data were obtained from 1045 isolates tested on the GenMark Dx ePlex Blood Culture Identification Gram-Negative Panels at the Mount Sinai Hospital Clinical Microbiology Laboratory in New York from March 2019 to February 2021. Susceptibilities were performed using Vitek 2 (bioMérieux Clinical Diagnostics) or Microscan (Beckman Coulter Inc.). blaCTX-M was detected in 26.4% Klebsiella pneumoniae, 23.5% Escherichia coli, and 16.4% Proteus mirabilis isolates. As would be expected, both blaCTX-M and blaCTX-M negative isolates were likely to be susceptible to newer agents while blaCTX-M positive isolates were more likely to be resistant to earlier generations of beta-lactam antibiotics. 3/204 blaCTX-M-positive isolates were found to be ceftriaxone-susceptible. Conversely, 2.8% ceftriaxone nonsusceptible strains were negative for all β-lactamase genes on the ePlex BCID-GN panel, including blaCTX-M. The prevalence of CTX-M-producing Enterobacterales remains high in the United States. A small number of blaCTX-M-positive isolates were susceptible to ceftriaxone, and a small number of ceftriaxone nonsusceptible isolates were negative for blaCTX-M. Further studies are needed to determine the optimal management when an isolate is phenotypically susceptible to ceftriaxone, but blaCTX-M is detected.IMPORTANCE There is limited literature on corresponding results obtained from rapid molecular diagnostics with the antibiotic susceptibility profile. We reported a correlation between the results obtained from ePlex and the antibiograms against a large collection of Gram-negative bacteria. We reported that there can be a discrepancy in a small number of cases, but the clinical significance of that is unknown.

Daptomycin susceptibility testing and therapeutic use in enterococcal bloodstream infection (EBSI) in a setting with high rates of vancomycin-resistant Enterococcus faecium (VREfm).

There is in vitro and clinical evidence to suggest daptomycin has good activity against Enterococcus. In 2019, CLSI produced clinical breakpoints for Enterococcus spp. To describe the distribution of MICs of daptomycin for enterococcal bloodstream infection (EBSI) isolates in a large Scottish health board, the indications for local daptomycin susceptibility testing and daptomycin doses used in vancomycin-resistant Enterococcus faecium (VREfm) infection. We investigated all EBSIs over a 21 month period and identified isolates tested against daptomycin. We recorded the distribution of MICs, as well as indications for daptomycin susceptibility testing and information on daptomycin dosing, where it was used. There were 293 blood culture isolates of Enterococcus spp., of which 37 had daptomycin susceptibility testing performed, from 31 individual patients. Of the 293 isolates, 103 were E. faecium, of which 63 were VREfm. Daptomycin testing was indicated by vancomycin resistance in 24/37 isolates. All E. faecium isolates tested were in the CLSI 'susceptible dose-dependent (SDD)' range of MICs. All other Enterococcus spp. tested were in the 'susceptible' range. Twelve patients received daptomycin, and dosing information was recovered for 10. Nine of these patients received 8-12 mg/kg/day dosing. There were no recorded adverse drug reactions. Ten of 12 patients were alive at the time of data collection. Daptomycin MIC distribution for EBSI isolates suggests a high local rate of susceptibility, according to CLSI breakpoints, in a population with high rates of VREfm. CLSI-recommended doses of daptomycin were used, with encouraging survival outcomes.

Reliable detection of MRSA bacteraemia by 4-hour cefoxitin disc diffusion

Methicillin susceptibility for Staphylococcus aureus blood culture isolates can be determined in 4 hours by cefoxitin disc diffusion using undiluted blood culture broth applied to Mueller-Hinton agar (MH) using a cotton swab. In 2020 a European Committee on Antimicrobial Susceptibility Testing (EUCAST) working group showed 58% of isolates were interpretable by this technique after 4 hours of incubation.1 We sought to increase the number of interpretable results by using Mueller-Hinton agar with sheep blood (MHSB) incubated at 35°C in air, and reading the zone of inhibition by reflected rather than transmitted light.