Coagulase-negative Staphylococci Isolates Research Articles

Co-resistance to methicillin and clindamycin among coagulase-negative staphylococci isolates recovered from pet food in Brazil

Pet food have been considered as possible vehicles of bacterial pathogens. The sudden boom of the pet food industry due to the worldwide increase in companion animal ownership calls for pet food investigations. Herein, this study aimed to determine the frequency, antimicrobial susceptibility profile, and molecular characteristics of coagulase-negative staphylococci (CoNS) in different pet food brands in Brazil. Eighty-six pet food packages were screened for CoNS. All isolates were identified at species level by MALDI-TOF MS and species-specific PCR. Antimicrobial susceptibility testing was performed by disc diffusion and broth microdilution (vancomycin and teicoplanin only) methods. The D-test was used to screen for inducible clindamycin phenotype (MLS-B). SCCmec typing and detection of mecA, vanA, vanB, and virulence-encoding genes were done by PCR. A total of 16 (18.6 %) CoNS isolates were recovered from pet food samples. Isolates were generally multidrug-resistant (MDR). All isolates were completely resistant (100 %) to penicillin. Resistances (12.5 % - 75 %) were also observed for fluoroquinolones, sulfamethoxazole-trimethoprim, tetracycline, rifampicin, erythromycin, and tobramycin. Isolates were susceptible to vancomycin (MICs <0.25–1 μg/mL) and teicoplanin (MICs <0.25–4 μg/mL). Intriguingly, 3/8 (37.5 %) CoNS isolates with the ERYRCLIS antibiotype expressed MLS-B phenotype. All isolates harboured blaZ gene. Seven (43.8 %) isolates carried mecA; and among them, the SCCmec Type III was the most frequent (n = 5/7; 71.4 %). Isolates also harboured seb, see, seg, sej, sem, etb, tsst, pvl, and hla toxin virulence-encoding genes (6.3 % - 25 %). A total of 12/16 (75 %) isolates were biofilm producers, while the icaAB gene was detected in an S. pasteuri isolate. Herein, it is shown that pet food is a potential source of clinically important Gram-positive bacterial pathogens. To the best of our knowledge, this is the first report of MLS-B phenotype and MR-CoNS in pet food in Latin America.

Inhibition of Clinical MRSA Isolates by Coagulase Negative Staphylococci of Human Origin.

Staphylococcus aureus is frequently highlighted as a priority for novel drug research due to its pathogenicity and ability to develop antibiotic resistance. Coagulase-negative staphylococci (CoNS) are resident flora of the skin and nares. Previous studies have confirmed their ability to kill and prevent colonization by S. aureus through the production of bioactive substances. This study screened a bank of 37 CoNS for their ability to inhibit the growth of methicillin-resistant S. aureus (MRSA). Deferred antagonism assays, growth curves, and antibiofilm testing performed with the cell-free supernatant derived from overnight CoNS cultures indicated antimicrobial and antibiofilm effects against MRSA indicators. Whole genome sequencing and BAGEL4 analysis of 11 CoNS isolates shortlisted for the inhibitory effects they displayed against MRSA led to the identification of two strains possessing complete putative bacteriocin operons. The operons were predicted to encode a nukacin variant and a novel epilancin variant. From this point, strains Staphylococcus hominis C14 and Staphylococcus epidermidis C33 became the focus of the investigation. Through HPLC, a peptide identical to previously characterized nukacin KQU-131 and a novel epilancin variant were isolated from cultures of C14 and C33, respectively. Mass spectrometry confirmed the presence of each peptide in the active fractions. Spot-on-lawn assays demonstrated both bacteriocins could inhibit the growth of an MRSA indicator. The identification of natural products with clinically relevant activity is important in today's climate of escalating antimicrobial resistance and a depleting antibiotic pipeline. These findings also highlight the prospective role CoNS may play as a source of bioactive substances with activity against critical pathogens.

Antibiotic Susceptibility and Biofilm Production among Coagulase Negative Staphylococci Isolated from Clinical Samples at Tertiary Care Hospital.

Coagulase Negative Staphylococci have been widely associated with medical device implant treatment and immune-compromised patients. Despite having increasing interest in Coagulase Negative Staphylococci, few studies from Nepal have reported the association of these organisms with urinary tract infections, conjunctivitis, high vaginal swabs, and cerebrospinal fluid. This study was carried out to determine antibiotic susceptibility pattern and biofilm production among Coagulase Negative Staphylococci isolated from clinical samples at tertiary care hospital. This study was a hospital based cross-sectional study in which 3690 clinical samples were included. Isolation and identification of isolates was done following standard microbiological protocol. Coagulase Negative Staphylococci were identified phenotypically on the basis of gram staining, slide and tube coagulase test and by various sugar fermentation tests. Antibiotic susceptibility test was done following Kirby Bauer disk diffusion method (Clinical and Laboratory Standards Institute 2020). Biofilm production was determined by Tissue Culture Plate technique. A total of 113 isolates of Coagulase Negative Staphylococci were detected. Among them S. epidermidis (45.1%), S. saprophyticus (23.9%), S. haemolyticus (16.8%), S. hominis (5.3%), S. capitis (2.7%), -----S. cohini (1.8%), S. lugdunensis (1.8%) and S. sciuri (2.7%) were identified phenotypically. All isolates were found to be resistant against Ampicillin and 111 (98.2%) were sensitive against Linezolid.23.9% of CoNS were strong biofilm producers, 19.5% moderate and 56.6 % were non/weak biofilm producers. It requires susceptibility test for prescribing antibiotics against Coagulase Negative Staphylococci in hospital and the misuse of antibiotics should be prevented.

Pathogenic potential of meat-borne coagulase negative staphylococci strains from slaughterhouse to fork.

This study aimed to determine the prevalence of coagulase-negative staphylococci (CoNS) in meat processing lines for their pathogenic potential associated with biofilm formation, staphylococcal toxin genes, and antibiotic resistance in obtained isolates. Out of 270 samples, 56 isolates were identified as staphylococcal with their species level, and their antimicrobial resistance profiles were also determined with the BD Phoenix™ system. Among these, CoNS were found in 32 isolates, including S. epidermidis (22%), S. warneri (22%), S. cohnii (9%), S. schleiferi (9%), S. capitis (6%), S. haemolyticus (6%), S. lugdunensis (6%), S. chromogenes (6%), S. kloosii (3%), S. sciuri (3%), S. lentus (3%), and S. caprae (3%). Biofilm formation was observed in 78.1% of CoNS isolates, with 56% being strong biofilm producers; and the frequency of the icaA, fnbA, and fnbB genes were 43.7% and 34.3%, and 9.3% in isolates, respectively. Twenty-five (78.1%) of these strains were resistant to at least one antimicrobial agent, 20 (80%) of which exhibited multidrug resistance (MDR). Regarding genotypic analyses, 15.6%, 22.2%, 87.5%, and 9% of isolates, were positive for blaZ, ermC, tetK, and aacA-aphD, respectively. In 8 (25%) of all isolates had one or more staphylococcal toxin genes: the sed gene was the most frequent (12.5%), followed by eta (9.3%), tst-1 (6.25%), and sea (3.1%). In conclusion, this study highlights meat; and meat products might be reservoirs for the biofilm-producing MDR-CoNS, which harbored several toxin genes. Hence, it should not be ignored that CoNS may be related to foodborne outbreaks.

Antibiotic Susceptibility Profiles of Bacterial Isolates Recovered from Abscesses in Cattle and Sheep at a Slaughterhouse in Algeria.

Abscesses represent the most prominent emerging problem in the red meat industry, leading to great economic constraints and public health hazards. Data on etiological agents present in these purulent lesions in Algeria are very scarce. The aim of this study was to identify the bacteria responsible for these abscesses and to determine their antibiotic susceptibility profiles. A total of 123 samples of abscesses from 100 slaughtered sheep and 23 slaughtered cattle were cultured in several media. A total of 114 bacterial isolates were cultured from 103 abscesses. Bacteria were identified using MALDI-TOF, and antibiotic susceptibility was determined by the disk diffusion method on Mueller-Hinton agar. A total of 73.6% (n = 84) corresponded to Enterobacterales, of which four were multidrug-resistant (MDR). These isolates, together with Staphylococcus aureus, coagulase negative Staphylococci, and seven randomly chosen susceptible Escherichia coli isolates, were further characterized using WGS. Resistome analysis of the four MDR Enterobacterales isolates revealed the presence of OXA-48 carbapenemase in two Klebsiella pneumoniae ST985 and one E. coli ST10 isolates and a CTX-M-15 ESBL in one E. coli isolate ST1706. Two coagulase-negative Staphylococci isolates were found to carry the mecA gene. WGS showed the presence of different resistance genes and virulence genes. Our study revealed 5% of MDR Enterobacterales (including ESBLs and carbapenemases) identified from abscesses, thus urging the need for abscess monitoring in slaughterhouses.

Genetic Diversification and Resistome of Coagulase-Negative Staphylococci from Nostrils of Healthy Dogs and Dog-Owners in La Rioja, Spain.

Coagulase-negative staphylococci (CoNS) species in healthy dogs and their owners could be transferred between these hosts and carry diverse antimicrobial resistance (AMR) genes of public health concern. This study determined the frequency, diversity, and AMR genes of nasal CoNS from healthy dogs and in-contact people as well as the rate of intra-household (between healthy dogs and dog-owners) transmission of CoNS. Nasal samples were collected and processed from 34 dogs and 41 humans from 27 households, and CoNS identification was done by MALDI-TOF-MS. The AMR determinants and genetic lineages were determined by PCR/sequencing. A total of 216 CoNS isolates were initially obtained and identified, and the AMR phenotypes were determined. From these, 130 non-repetitive CoNS were selected (one isolate of each species per sample or more than one if they presented different AMR phenotypes) and further characterized. The predominant species from dog carriers were S. epidermidis (26.5%), S. hominis (8.8%), and S. cohnii (8.8%), whereas in the human carriers, the predominant ones were S. epidermidis (80.4%), S. lugdunensis (9.8%), and S. hominis (9.8%). Intra-host species diversity (>one CoNS species) was detected in 37.5% of dogs and 21.6% of dog-owners. Conversely, 50% of dogs and 70.3% of dog-owners had intra-species AMR diversity (2-4 AMR-CoNS profiles). About 20% were susceptible to all antimicrobial agents tested, 31.5% displayed a multidrug resistance phenotype, and 17.4% were mecA-positive, located in SCCmec type V (24.2%), III (18.1%), IVc (12.1%), and II (6.1%). The other mec-A positive CoNS isolates (39.5%) had non-typeable SCCmec. The highest AMR rates were found against erythromycin (32.3%/mph(C), msr(A)) and mupirocin (20.8%/mupA), but the resistance rates for other antimicrobial agents were <10% each. Remarkably, one linezolid-resistant S. epidermidis-ST35 isolate was identified and mediated by four amino acid substitutions in L3 and one in L4 ribosomal proteins. Dogs and dog-owners as carriers of S. epidermidis with similar AMR patterns and genetic lineages (ST59, ST61, ST166 and ST278) were detected in four households (14.8%). Diverse CoNS carriage and moderate level of AMR were obtained from this study. The detection of CoNS carrying diverse SCCmec elements and intra-species AMR diversity highlights the roles of dog ownership in the potential transmission of antimicrobial-resistant CoNS in either direction.

Clinical Impact of Vancomycin MIC on Outcomes in Patients With Coagulase-negative Staphylococcal Bacteremia

Coagulase-negative staphylococci (CoNS) are Gram-positive organisms that are a known component of normal skin flora and the most common cause of nosocomial bacteremia. For CoNS species, the vancomycin MIC breakpoint for susceptibility set by the Clinical and Laboratory Standards Institute is ≤4 µg/mL. There has been published reports of vancomycin heteroresistance in CoNS with vancomycin MICs of 2 to 4 µg/mL. The aim of this retrospective cohort analysis was to assess the clinical impact of vancomycin MICs <2 µg/mL versus ≥2 µg/mL in adult patients with CoNS bloodstream infections. Adult patients admitted to University Medical Center New Orleans with a blood culture positive for CoNS were assessed. The primary outcome was difference in 30-day mortality. Secondary outcomes were in-hospital, all-cause mortality; duration of bacteremia; hospital length of stay; and percentage of oxacillin-resistant CoNS. There was no difference in mortality in the vancomycin MIC <2 µg/mL group versus the vancomycin MIC ≥2 µg/mL group at 30 days (15.4% vs 17.4%; P = 1). In-hospital, all-cause mortality was also not different between groups (11.5% vs 13%; P = 1). Hospital length of stay between groups was 28.2 days versus 21 days (P = 0.692). Median duration of bacteremia was 1 day in both groups (P = 0.975), and median scheduled duration of antibiotic therapy was 14.9 days and 19.5 days (P = 0.385). The source and mode of acquisition of CoNS were similar between groups. Of all CoNS isolates, 58.7% (44 of 75) were oxacillin resistant. Staphylococcus epidermidis was the most common CoNS species at 66.7% (50 of 75). Of all isolates, 30.7% (23 of 75) had a vancomycin MIC ≥2 µg/mL, and 87% (20 of 23) of these were S. epidermidis. There was a higher percentage of S. epidermidis in the vancomycin MIC ≥2 µg/mL group than in the MIC <2 µg/mL group (87% vs 57.7%; P = 0.012). CoNS with a vancomycin MIC ≥2 µg/mL were also more likely to be oxacillin resistant (78.3% vs 50%; P = 0.005). There was no difference in clinical outcomes in adult patients with a CoNS bloodstream infection with a vancomycin MIC <2 µg/mL versus ≥2 µg/mL. At present, vancomycin remains appropriate empiric therapy for CoNS bloodstream infection. Further research is needed to determine if there is a true clinical impact of a vancomycin MIC ≥2 µg/mL in CoNS infections.

Molecular characterization of antimicrobial resistance and virulence factors in coagulase – negative staphylococci nasal isolates among adult patients in a tertiary hospital in North-Western Nigeria

Coagulase-negative staphylococci are harmless microorganisms that can become pathogenic when the host resistance is impaired. Their ability to exhibit multidrug-resistance and form biofilm limit treatment options and contributes to the health and financial burden on health care systems worldwide. This study aimed to provide data on the acquisition and expression of genetic elements associated with resistance and virulence in the organisms from nasal colonization of adults admitted to a University Teaching Hospital in Nigeria. One hundred and twenty-three presumptive staphylococci isolates were obtained from the medical microbiology laboratory of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria. The isolates were characterized, and the antibiotics susceptibility pattern assessed. Biofilm formation was evaluated by the micro-titre plate method, and polymerase chain reaction was used to detect resistance genes (mecA and ermB), virulence gene (psm-mec) and adhesin genes, (icaAB, icaC and icaD) in the isolates. Out of the 60 coagulase-negative staphylococci isolates, 50 (83.3%) were strong biofilm formers, 5 (8.3%) were moderate biofilm formers and 5 (8.3%) were weak biofilm formers. For the 14 isolates that were characterized by PCR, mecA and ermB resistance genes were detected in 78% and 71% of the isolates respectively. Twenty-one percent had psm-mec virulence gene while biofilm adhesin genes, icaAB and icaD were detected in 36% and 57% respectively, icaC gene was not detected. This study confirmed formation of biofilm, carriage of resistance and virulence genes which have been shown to play a role in pathogenesis. This study shows the necessity of the periodical monitoring of the drug resistance pattern and virulence factors of coagulase-negative staphylococci.

Characterization of virulence factors and antimicrobial resistance in Staphylococcus spp. isolated from clinical samples.

The virulence factors, antibiotic resistance patterns, and the associated genetic elements have been investigated in Staphylococcus species. A total of 100 strains has been isolated from clinical samples in the Microbiology Laboratory of Hesperia Hospital, Modena, Italy, and identified as Staphylococcus aureus (65), Staphylococcus epidermidis (24), Staphylococcus hominis (3), Staphylococcus saprophyticus (3), and Staphylococcus warneri (5). All the strains were analyzed to determine phenotypic and genotypic characters, notably the virulence factors, the antibiotics susceptibility, and the genetic determinants. The highest percentage of resistance in Staphylococcus spp. was found for erythromycin and benzylpenicillin (87% and 85%, respectively). All S. aureus, two S. epidermidis (8.3%), and one S. saprophyticus (33.3%) strains were resistant to oxacillin. The methicillin resistance gene (mecA) was detected by polymerase chain reaction (PCR) amplification in 65 S. aureus strains and in 3 coagulase-negative staphylococci (CoNS) (8.6%). With regard to the virulence characteristics, all the S. aureus were positive to all virulence tests, except for slime test. Among the CoNS isolates, 19 (79.1%) S. epidermidis and one (33.3%) S. saprophyticus strains resulted positive for the slime test only. The results obtained are useful for a more in-depth understanding of the function and contribution of S. aureus and CoNS antibiotic resistance and virulence factors to staphylococcal infections. In particular, the production of slime is very important for CoNS, a virulence factor frequently found in infections caused by these strains. Further investigations on the genetic relatedness among strains of different sources will be useful for epidemiological and monitoring purposes and will enable us to develop new strategies to counteract the diffusion of methicillin-resistant S. aureus (MRSA) and CoNS strains not only in clinical field, but also in other related environments.

Resistome, mobilome, and virulome explored in clinical isolates derived from acne patients in Egypt: unveiling unique traits of an emerging coagulase-negative Staphylococcus pathogen.

Coagulase-negative staphylococci (CoNS) are a group of gram-positive staphylococcal species that naturally inhabit the healthy human skin and mucosa. The clinical impact of CoNS-associated infections has recently been regarded as a challenge for diagnosis and therapeutic options. CoNS-associated infections are primarily caused by bacterial resistance to antibiotics and biofilm formation. As antibiotics are still the most used treatment, this problem will likely persist in the future. The present study aimed to investigate the resistance and virulence of CoNS recovered from various acne lesions and explore their genetic basis. Skin swab samples were collected from participants with acne and healthy skin. All samples underwent conventional culture for the isolation of CoNS, MALDI-TOF confirmation, antibiotic susceptibility, and biofilm formation testing. A total of 85 CoNS isolates were recovered from the samples and preliminarily identified as Staphylococcus epidermidis. Isolates from the acne group (n = 60) showed the highest rates of resistance to penicillin (73%), cefoxitin (63%), clindamycin (53.3%), and erythromycin (48%), followed by levofloxacin (36.7%) and gentamycin (31.7%). The lowest rates of resistance were observed against tetracycline (28.3%), doxycycline (11.7%), and minocycline (8.3%). CoNS isolated from mild, moderate acne and healthy isolates did not show strong biofilm formation, whereas the isolates from the severe cases of the acne group showed strong biofilm formation (76.6%). Four extensively drug-resistant and strong biofilm-forming staphylococcal isolates recovered from patients with severe acne were selected for whole-genome sequencing (WGS), and their genomes were investigated using bioinformatics tools. Three of the sequenced genomes were identified as S. epidermidis; however, isolate 29AM was identified as Staphylococcus warneri, which is a newly emerging pathogen that is not commonly associated with acne and was not detected by MALDI-TOF. All the sequenced strains were multidrug-resistant and carried multiple resistance genes, including blaZ, mecA, tet(K), erm(C), lnuA, vgaA, dfrC, fusB, fosBx1, norA, and vanT, which were found to be located on plasmids and chromosomes. Virulence features were detected in all genomes in the presence of genes involved in adherence and biofilm formation (icaA, icaB, icaC, sdrG, sdrH, atl, ebh, and ebp). Only the S. warneri isolate 29AM contained immune evasion genes (capB, capC, acpXL, and manA), an anti-phagocytosis gene (cdsA), and other unique features. As a result of their potential pathogenicity and antibiotic resistance, CoNS must be monitored as an emerging pathogen associated with acne infections. To the best of our knowledge, this is the first report to isolate, identify, and correlate S. warneri with severe acne infections among Egyptian patients using WGS and bioinformatic analysis.

Isolation and Identification of Methicillin Resistant Staphylococci at Bethzatha Advanced Laboratory, Addis Ababa, Ethiopia

Methicillin resistant Staphylococcus aureus and coagulase negative staphylococci (CoNS) are widely spreading. So identification and antimicrobial susceptibility tests of methicillin resistant S. aureus and coagulase negative staphylococcus (CoNS) is critical to appropriately treat patients and control the increasing spread of these pathogens. Therefore the aim of the present work is to determine methicillin resistant S.aureus and CoNS from clinical samples sent to BethZatha Advanced Laboratory from different health institutions and Bethzatha Hospital, Addis Ababa, for bacterial isolation, identification and antimicrobial susceptibility. Bacterial isolation, identification and antimicrobial susceptibility testing were done using Microscan panel methods (Beckman Coulter, Brea, CA, USA) from May 2021 to February 2022 at Bethzatha advanced Medical Laboratory. The retrospective data was analysed to determine methicillin susceptibility of S.aureus and Coagulase negative staphylococci (CoNS). The finding shows 35% (40/114) S. aureus and 65.8% (75/114) coagulase negative staphylococci (CoNS) were isolated from different clinical specimens (urine, blood culture, pus and discharges). Out of 40 S. aureus isolates 30% (12/40) were methicillin resistant. Similarly, out of 75 CoNS, 52% (39/75) were methicillin resistant. Almost all methicillin resistant S. aureus and most CoNS isolates were multiply resistant to amoxicillin clavulnate, azithromycin, penicillin and ampicillin. Periodic surveillance and appropriate control measures and safety precautions of nosocomial and community acquired methicillin resistant multidrug resistant, staphylococcus aureus, and CoNS must be given prior attention.

Bacteriological Profile and Antibiogram of Aerobic Blood Culture Isolates among Suspected Blood Stream Infections: A Cross-sectional Study

Introduction: Bloodstream Infections (BSIs) are important causes of morbidity and mortality worldwide. Blood culture is the most important diagnostic tool for BSI. The epidemiology and outcome of BSI are constantly changing due to increasing antimicrobial resistance, changing patterns of antibiotic drug usage, and the increased use of transient or permanent medical devices. Thus, regular monitoring of the bacterial aetiology of BSI and their antibiograms is necessary. Aim: To determine the bacteriological profile and antibiotic susceptibility patterns among suspected BSI patients. Materials and Methods: A hospital-based cross-sectional study was carried out in the Department of Microbiology, Jawaharlal Nehru Institute of Medical Sciences (JNIMS), Imphal, Manipur, India, from September 2018 to August 2020. A total of 481 suspected BSI patients were included in the study. The blood culture samples were collected under aseptic conditions and cultured for seven days. The isolates were identified using conventional biochemical tests, and the antibiotic susceptibility pattern was determined by the Kirby-Bauer disk diffusion method and the epsilometer test (E-test). Methicillin resistance among the staphylococcal isolates was detected using the cefoxitin disk diffusion method. Data analysis was performed using EpiInfoTM version 7.0, and the Chi-square test was used as a statistical test. Results: A total of 150 (31.2%) blood samples were culture positive out of the 481 samples processed from suspected BSI patients. The predominant isolates were gram-positive, accounting for 113/150 (75.3%), while gram-negatives accounted for 37/150 (24.7%). Staphylococcus aureus, Pseudomonas aeruginosa, and Coagulase Negative Staphylococci (CoNS) were the primary pathogens isolated. Methicillin resistance was detected in 59 (54.6%) of the staphylococcal isolates {52 (54.7%) were Methicillin Resistant S. aureus (MRSA), and out of the 13 CoNS isolates, 7 (53.9%) were Methicillin Resistant CoNS (MRCoNS)}. The most susceptible drugs for gram-positives were vancomycin and linezolid, while aminoglycosides and imipenem were the most susceptible drugs for gram-negatives. Conclusion: The study highlighted the prevalence and pattern of aerobic bacterial isolates in BSI cases at JNIMS Hospital, as well as, the antibiotic susceptibility patterns of the isolates. Regular epidemiological studies of BSIs, regarding the pathogens and their antibiotic susceptibility patterns, are necessary to guide clinicians in choosing appropriate empirical therapy and to update the hospital antibiotic policy from time to time. This promotes rational antibiotic use and reduces resistance among bacteria.

Incidence of Coagulase Negative Staphylococci in Various Clinical Samples in Tertiary Care Hospital, Nepal

Objectives: To determine incidence of coagulase negative Staphylococci (CoNS) in various clinical samples along with the study of their multi drug resistance, methicillin resistance and biofilm formation. Methods: A hospital based cross-sectional study was conducted which included 1875 clinical samples. The isolation and identification of isolates was done following standard microbiological protocol. The CoNS were identified phenotypically on the basis of gram staining, slide and tube coagulase test and through various carbohydrates fermentation tests. Antibiotic susceptibility test was done by Kirby Bauer disk diffusion method (Clinical and Laboratory Standards Institute 2020) whereas biofilm production was determined by Tissue Culture Plate (TCP) technique. Results: A total of 32 CoNS, comprising of 6 species were identified. S. epidermidis (43.8%) was the most common species isolated followed by S. saprophyticus (28.1%), S. haemolyticus (15.6%), S. hominis (6.3%), S. lugdunensis (3.1%) and S. cohini (3.1%). Further, 27 (84.4%) of CoNS were found to be multidrug resistant, 22 (68.8%) methicillin resistant and 8 (25%) showed positive D- test. Strong biofilm production was detected in 9 (28.1%) isolates of CoNS, 10 (31.3%) were moderate biofilm producers and 13 (40.6%) non/weak biofilm producers. The equal distribution, 9 (33.3%) each of strong, moderate and non/weak biofilm producers were found among 27 isolates of MDR. Among 22 methicillin resistant isolates, 9 (40.9%), 7 (31.8%) and 6 (27.3%) were strong, moderate and non/ weak biofilm producers respectively. All isolates were sensitive against Linezolid followed by Cotrimoxazole. Conclusion: The increasing multi drug resistance among CoNS should be rationally approached with the use of proper antibiotics while treating the patients.

Species distribution and antimicrobial susceptibility pattern of coagulase-negative staphylococci isolated from clinical specimens at a tertiary care hospital

Background and objectives: Coagulase-negative staphylococci (CoNS) are considered important causative agents of hospital acquired infection. These organisms are found in various clinical specimens from hospitalized patients. Present study was carried out to determine the species distribution and antimicrobial susceptibility pattern of CoNS isolated from clinical specimens at a tertiary care hospital. Materials and methods: CoNS isolated from various clinical samples were included in this study. The isolates were identified by colony morphology, Gram’s staining, catalase and coagulase tests. Further differentiation of species was performed by susceptibility to novobiocin, urease activity and ornithine decarboxylase test. Antibiotic susceptibility testing was performed according to the Clinical and Laboratory Standard Institute (CLSI) guidelines. Results: Total 108 isolates of CoNS were included and analysed. Out of 108 CoNS, S. epidermidis was the most common species (36.1%) followed by S. saprophyticus (23.1%), S. hemolyticus (17.6%), S. hominis (13%) and S. lugdunensis (10.2%). Most of the isolates showed resistance to penicillin, oxacillin, amoxycillin, erythromycin, ciprofloxacin and ofloxacin. All the isolates were sensitive to vancomycin. Conclusions: CoNS emerged as an important nosocomial pathogen and should not be neglected as contaminant. High rate of antimicrobial resistance warrants susceptibility testing prior to the treatment of CoNS. IMC J Med Sci. 2024; 18(1):010. DOI: https://doi.org/10.55010/imcjms.18.010 *Correspondence: Sabiha S Tamboli, Department of Microbiology, Parbhani Medical College and RP Hospital Research Institute, Pathri Road, Parbhani, Maharashtra, India. Email: sabihatamboli77@gmail.com

Bacteriological Profile and Antibiogram of Isolates Causing Bloodstream Infection in Children

Objective: (1) To identify and characterize bacterial isolates causing blood stream infection in children. (2) To determine the antibiotic sensitivity pattern of isolates obtained. Materials And Methods: Study design: Descriptive study. Study population: Blood samples collected from pediatric patients aged upto 12 years who are admitted in Government Medical College Kottayam, with clinical features of blood stream infection. Sampling methodology: The sample size of suspected blood stream infection is 345. All pediatric patients with clinical features suggestive of blood stream infection in the study period satisfying inclusion and exclusion criteria will be included in the study. The identification of bacterial pathogens and antimicrobial susceptibility tests were done by conventional and automated methods like VITEK system. Results: Out of 345 study sample population, 46 were culture positive, of which 21(45.7%) were Gram negative isolates and 20(43.4%) were Gram positive. Major isolates obtained were Klebsiella spp (15%), Methicillin Resistant Coagulase negative Staphylococci (15%), followed by Staphylococcus aureus (13%), Coagulase negative Staphylococci (8%) and Acinetobacter baumannii (8%). Klebsiella pneumoniae was resistant to most of the antibiotics tested except meropenem. All isolates of Coagulase negative Staphylococci and Staphylococcus aureus were susceptible to vancomycin and linezolid. Conclusion: Gram negative organisms were predominant pathogens in blood stream infections. Klebsiella pneumoniae, Coagulase negative Staphylococci, Staphylococcus aureus were the most commonly isolated pathogens. Amikacin along with the third generation cephalosporins should be used for empirical treatment of Gram negative sepsis. Vancomycin and linezolid can be used for Gram positive pathogens.

Utility of Echocardiogram in Neutropenic Patients with Gram Positive Bacteremia: A Retrospective Study

Introduction: Hemato-oncology patients are vulnerable to bloodstream infections (BSI) due to their immunocompromised and neutropenic state, and the common use of intravascular catheters. The risk of infective endocarditis (IE) among non-neutropenic patients with gram positive bacteremia is substantial, however the risk is considered to be lower among neutropenic patients, though data is limited. We aimed to evaluate the incidence of IE among neutropenic hemato-oncology patients' cohort, and to explore the yield of echocardiogram in this specific population. Methods: A single center, retrospective study. Between 01/2007 and 12/2019, hospitalized patients in the Hematology department consisting of the hemato-oncology and bone marrow transplantation units were included, if they had positive blood cultures for specific organisms known to cause IE while neutropenic. Patient characteristics, results and timing of blood cultures and echocardiogram obtained during hospitalization were collected. Results: Two hundred seventy-four patients had positive blood cultures with pathogens known to be associated with IE. Overall, 340 isolates have been identified. After excluding 57 coagulase negative staphylococcus (CONS) isolates which were suspected as a contamination (identified in a single collection), 241 patients were included with 283 isolates. CONS were the most commonly isolates found, followed by streptococcus viridans, comprising 31.4% (89) and 24.3% (69) of isolates, respectively. Trans thoracic echocardiography (TTE) was performed in 108 (45%) patients overall, of which 14 (5.8%) had additional trans esophageal echocardiogram (TEE). Only one case of IE was diagnosed in our series, of a forty-seven-year-old female patient with a diagnosis of multiple myeloma in relapse after autologous stem cell transplantation. The patient presented with a stroke caused by septic emboli, fever and streptococcus viridans bacteremia. Lab works showed neutropenia of 0K/micl and thrombocytopenia of 8K/micl. TTE and TEE failed to demonstrate valvular pathology consistent with IE in this case. Valvular vegetations have not been identified on TTE nor on TTE in any other case as well. Conclusion In our experience, the yield of echocardiogram in hemato-oncological neutropenic patients with gram positive bacteremia is extremely low, owing to reduced probability of IE in this population, and thus could be avoided in most cases.

A Comparison of the Minimum Inhibitory Concentration of Antibiotics in Staphylococcus Species Isolated From Orthopedic and Respiratory Medicine Infections.

Antibiotic susceptibility is very important for the successful treatment of orthopedic infections, particularly for implant-related infections. While the minimum inhibitory concentrations (MICs) of Staphylococcus species were well investigated for the isolates from the respiratory tract, investigations for orthopedic pathogens are very limited. We investigated the antibiotic MIC values of Staphylococcus species isolated from orthopedic infections and compared them with those of respiratory medicine isolatesused as a control. The MICs of vancomycin (VCM), arbekacin (ABK), teicoplanin (TEIC), linezolid (LZD), and rifampicin (RFP) of a total of consecutive 259 (89 orthopedic and 170 respiratory) Staphylococcus speciesisolated in our laboratory from January 2013 to July 2016 were retrospectively reviewed. Differences between the MICs of each antibiotic in orthopedic and respiratory samples were determined. The number of methicillin-sensitive Staphylococcus aureus (MSSA) with a VCM MIC of <0.5 μg/mL among respiratory isolates was significantly higher than that among orthopedic isolates, while those with a MIC of 2 μg/mL were significantly lower (P = 0.0078). The proportion of methicillin-resistant coagulase-negative staphylococci (MRCNS) isolates with a VCM MIC of 2 μg/mL was significantly higher in orthopedic samples than that of methicillin-resistant Staphylococcus aureus (MRSA) (P < 0.001) in respiratory isolates. The proportion of MRCNS orthopedic isolates with an RFP MIC of >2 μg/mL was significantly higher (P = 0.0058) than that of other orthopedic staphylococci. The VCM MICs of Staphylococcus species from orthopedic infections were higher than those of respiratory samples, particularly MRCNS from implant-related samples.

2408. Is Shorter Antibiotic Treatment Feasible in Patients with Cardiac Implantable Electronic Devices (CIED) Infections? Impact of Treatment Duration on 6-Month Recurrence and Mortality

Abstract Background Aim of this study is to compare the 6-month outcomes (recurrence and mortality) of patients with cardiac implantable electronic device (CIED) infections treated with short (SHORT, &amp;lt;14 days) or long (LONG, &amp;gt;14 days) duration of antimicrobial therapy after device removal. Methods Retrospective cohort study of patients hospitalized at IRCCS San Raffaele Hospital (Milan, Italy) from June 2011 to June 2021, who underwent device removal for CIED infection. Patients with pocket and lead infections were included, while valve endocarditis and Staphylococcus aureus infection were excluded. The characteristics of patients in the SHORT and LONG groups were compared using the chi-square test for categorical variables and the Mann-Whitney U-test for continuous variables. A propensity score (PS) was calculated using a logistic regression that considered duration of therapy as the dependent variable; the association between patients’ characteristics and outcomes was evaluated with logistic regression analysis. Results The characteristics of the 150 included patients are described in table 1, the microbial etiology in table 2. Patients in the SHORT compared to the LONG group were older (75 [65-80] vs 69 [62-77], p-value=0.047), had a higher Charlson comorbidity index (5 [3-6] vs 4 [3-5], p-value=0.021), had less frequent isolation of coagulase-negative staphylococci (CoNS; 46.7% vs 68.9%, p-value=0.006), and an unknown etiology (36.7% vs 13.3%, p-value=0.001). Moreover, the duration of antimicrobial treatment after device removal was shorter (13 [9-14] vs 20 [16-29] days, p-value&amp;lt; 0.001). At 6 months, recurrence and mortality were not significantly different between the SHORT and the LONG group (recurrences: 2 [3.7%] vs 5 [6.7%], p-value=0.464; mortality: 2 [3.7%] vs 3 [4.0%], p-value=0.931), At logistic regression analysis (table 3 and table 4) adjusted for PS, treatment duration was not significantly associated with either recurrence (odds ratio [OR] 0.524; 95% confidence interval [95%CI] 0.084-3.263) or mortality (OR 1.402; 95%CI 0.185-10.635). Conclusion A shorter duration of antimicrobial treatment after device removal may be an effective approach for treating patients with CIED infections. Disclosures Antonella Castagna, MD, Bristol-Myers Squibb: consultancy payments and speaking fees|Gilead: consultancy payments and speaking fees|Janssen-Cilag: consultancy payments and speaking fees|Merck Sharp &amp; Dohme: consultancy payments and speaking fees|ViiV Healthcare: consultancy payments and speaking fees

Nasal staphylococci microbiota and resistome in healthy adults in La Rioja, northern Spain: High frequency of toxigenic S. aureus and MSSA-CC398 subclade

This study determined the nasal staphylococci diversity and characterized their resistome, with a focus on the mobilome of methicillin-susceptible Staphylococcus aureus (MSSA)-CC398 subclade from healthy adults in La Rioja (northern Spain). Nasal staphylococci recovered from 57 healthy individuals (HI) were identified (MALDI-TOF-MS) and their antimicrobial resistance, virulence determinants and genetic lineages were studied. The relatedness of MSSA-CC398 isolates was assessed by core-genome single-nucleotide-polymorphisms (SNPs). One-hundred-forty-three non-repetitive staphylococci were obtained from most HI (98.2%), of which S. epidermidis (87.7%) and S. aureus (36.8%) were the predominant species. About 15% of the 27 S. aureus and 30.1% of the 116 coagulase-negative staphylococci (CoNS) isolates presented a multidrug resistance (MDR) phenotype. All S. aureus isolates were MSSA but 30.2% of CoNS isolates were mecA-positive and carried SCCmec types III, IV, and V. The highest non-beta-lactam resistance (frequency/genes) in S. aureus and CoNS were: erythromycin-clindamycin-inducible (25.9%/ermT, ermC) and mupirocin (30.1%/mupA), respectively. About 85% of S. aureus isolates carried relevant virulence genes. Eight clonal complexes (CCs) of MSSA were identified, of which CC398 was the predominant (33.3%). About 78% of the CC398 isolates harboured rep13-bound ermT gene, however, one carried a rep10-bound ermC gene. Only the ermT-positive MSSA-CC398 isolates were closely related (<50 SNPs) and carried the φSa3. Diverse MDR-S. epidermidis isolates were identified which included the lineages ST59 and ST210. The high rate of toxigenic S. aureus and of MSSA-CC398 subclade highlight the ability of HI to carry and transmit virulent isolates. Moreover, the high frequency of MDR-CoNS, often linked with SCCmec, needs to be monitored for their potential human health implications.

The relevance of coagulase-negative Staphylococcus isolates in blood culture in the context of a tertiary neonatal unit from East India

Background: Coagulase-negative Staphylococcus (CoNS) are known commensals and often contaminate neonatal blood cultures. Their unique ability to form biofilms, however, helps them evade immune mechanisms and antibiotics and cause neonatal sepsis (NS) in hospitalized neonates. True or probable Coagulase-negative Staphylococcus blood stream infection (CoNS BSI) must be differentiated from contaminants so that antibiotics are used judiciously and hospital stay is minimized. Aims and Objectives: The primary objective of the study was to estimate the proportion of NS and contaminants among CoNS-positive blood cultures in the index neonatal unit and the host and health-care variables associated with CoNS BSI. The secondary objective was to estimate the susceptibility of CoNS isolates to antibiotics used. Materials and Methods: This was a retrospective study from digital records, from January 2018 to December 2022. Results: 25% of CoNS isolates were associated with NS (health-care infections) and 75% were contaminants. Over 90% of CoNS BSI was associated with central lines (CLs) and prolonged hospital stay. All isolates were resistant to oxacillin while resistance to gentamicin rose annually to over 68%. Susceptibility to linezolid and vancomycin was present, but a few strains were resistant to them. Conclusion: CoNS were an important cause of NS in the index hospital. Prolonged hospital stays and CLs were associated with increased incidence of CoNS sepsis and must be minimized where possible. Antibiotic resistance was high, and reserve drugs could also become ineffective.