Methicillin-susceptible Staphylococci Research Articles

Phenotypic Characterization of Methicillin-Resistant Staphylococci Isolated from Wounds and Nasal Swabs in Selected Hospitals Across some Northwestern States, Nigeria

Study’s Novelty/Excerpt This study provides a comprehensive analysis of Methicillin-resistant Staphylococci (MRS) from wounds and nasal swabs in Northwestern Nigeria, focusing on the phenotypic characteristics, antibiotic susceptibility, and socio-demographic profiles of the isolates. The novelty lies in its extensive sampling across nine facilities in four states and its detailed examination of the correlation between educational and economic status and MRS occurrence, which has not been previously reported. These findings offer critical insights for healthcare policy-making in antibiotic usage and infection control in a region-specific context, highlighting socio-demographic factors influencing MRS prevalence. Full Abstract Methicillin-resistant Staphylococci (MRS) remain important opportunistic pathogens most frequently identified worldwide. The study aimed to determine the phenotypic characteristics of Methicillin-resistant Staphylococci, their antibiotic susceptibility patterns, and the socio-demographic characteristics of the isolates from wounds and nasal swabs in selected hospitals across some states in Northwestern Nigeria. A total of 806 wounds and nasal swabs were collected from patients admitted at nine facilities in 4 states of Northwestern Nigeria. All samples underwent analysis using standard bacteriological techniques. Antibiotic susceptibility testing (AST) was conducted using the Kirby-Bauer technique. Out of 806 samples, 652 (80.3%) were culture positive, while 154 (19.1%) were culture negative. A total of 704 (87.3%) isolates were obtained, out of which 418 (59.4%) were identified as Staphylococci isolates, comprising 144 (17.7%) Methicillin-resistant Staphylococcus aureus (MRSA), 124 (15.4%) Methicillin-susceptible Staphylococcus aureus (MSSA), 89 (11%) Methicillin-resistant coagulase-negative Staphylococci (MRCoNS), and 61 (7.6%) Methicillin susceptible coagulase-negative Staphylococci (MSCoNS). The Staphylococci isolates showed the highest susceptibility to Vancomycin 408 (97.6%), while the lowest was penicillin 24 (5.7%). The isolation rate of MRS was highest among patients aged 11-30, while the 71-90 age group had the lowest rate. The occurrence was higher (37%) in male patients than in female patients (18.6%). Moreover, there was no statistically significant association found between the distribution of MRS among different age groups, gender, and occupational affiliations, but it exists in the educational levels, and economic statuses of the research participants. The occurrence of MRS was lower among patients with a high level of formal education but higher among those without or with a low level of education. These findings will aid healthcare workers in establishing policies for antibiotic usage, surveillance, and infection prevention and control measures.

Population pharmacokinetic meta-analysis of five beta-lactams antibiotics to support dosing regimens in dogs for surgical antimicrobial prophylaxis

The Pharmacokinetic/Pharmacodynamic (PK/PD) relationship of antimicrobial drugs (AMD) for surgical prophylaxis has been poorly studied, hampering evidence-based decision making around AMD dosing and timing. Our objective is to use PK/PD principles to inform (1) the timing of administration and (2) the interval for re-administration of AMD used peri-operatively in dogs. Raw plasma concentrations of cefazolin, cefuroxime, cefalexin, amoxicillin and ampicillin were retrieved from original intravenous studies performed in dogs. E. coli and methicillin-susceptible staphylococci were identified as possible intraoperative contaminants and their epidemiological cut-offs (ECOFF) were retrieved from the EUCAST database. Individual PK data were refitted with non-linear mixed effect models (Phoenix®). We performed Monte Carlo simulation to compute i) the 95th percentile of time of peak concentration in the peripheral compartment (informing timing between administration and first incision) and ii) the duration for which at least 90% of dogs maintain a free plasma concentration above ECOFF (informing timing of re-administration: 1.5–4 h). Cefazolin (22–25 mg/kg), cefuroxime (20 mg/kg), cefalexin (15 mg/kg) and amoxicillin (16.7 mg/kg) reached peak peripheral concentrations within 30 min, but ampicillin (20 mg/kg) required 82 min, respectively. For methicillin-susceptible staphylococci, cefazolin and cefuroxime require re-administration every 2 h, whereas cefalexin and both amoxicillin and ampicillin can be readministered every 3 and 4 h, respectively. For E. coli, only cefazolin provided adequate perioperative coverage with 2-hourly administration, where cefuroxime and cefalexin failed uniformly. Alternatively, ampicillin and amoxicillin (critically ill dogs) may cover E. coli contaminations, but only if readministered every 1.5 h. These PK-derived conclusions provide a rationale for perioperative AMD administration timing.

Microorganism diversity and contamination risk in mosque rosaries and carpets.

Inevitably, the floors of mosques are contaminated with microorganisms, and the risk of pathogen transmission is probably high between the many visitors, but the issue has been infrequently studied. Investigate microorganism variety and risk of contamination on commonly used carpets and rosaries (prayer beads). Cross-sectional. Mosques. This study was carried out in three different cities of Turkey in 2023, focusing on mosques located around hospitals. Forty mosques were included in the study and from each mosque 10 samples were collected from various parts of carpets and rosaries. The number of positive culture isolates were identified. Diversity and distribution of microorganisms isolated from mosque carpets and rosaries; methicillin-resistance rates in Staphylococci. 400 samples. Growth was observed in 368 (92%) of 400 samples examined. The microorganisms isolated in the highest number were methicillin-susceptible coagulase negative Staphylococci (MSCoNS) (59.8%), Microcooccus (41%) and diphtheroids (31.3%). The rates of total growth (P=.001), including diphtheroids (P=.018), methicillin-resistant coagulase negative Staphylococci (P=.001), Bacillus spp. (P=.036) and Aspergillus spp. (P=.002) rates were significantly higher in the rosary samples than carpet samples. At mosques in Tokat, a province center, 4 samples were positive for Acinetobacter baumannii, two samples were positive for Pseudomonas aeruginosa and one sample for methicillin-resistant Staphylococcus aureus (MRSA), and these were isolated from rosaries. 0.3% of Staphylococcus isolates were MRSA. As there is a high risk of contamination of carpets and prayer beads on the mosque floor with human flora, the use of appropriate hygiene practices is necessary. We also found some emerging bacteria in addition to the normal human flora. Our study was conducted in three provinces. Further studies might cover a wider geography.

Prevalence of methicillin and clindamycin resistant Staphylococcus species at a tertiary hospital in Tanzania: Implications for antibiotic stewardship and infection management

Methicillin and clindamycin resistance (constitutive and inducible) pose a common clinical challenge in treating Staphylococcal infections. This cross-sectional study, conducted at Muhimbili National Hospital (MNH) in Tanzania from April to June 2023, to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and clindamycin-resistant Staphylococcus (S.) species by using a cefoxitin disk (30 μg) and the D-test method as per CLSI 2022 guidelines. Of the 361 clinical samples, 125 (34.6%) were culture-positive. Among Staphylococcus spp., S. aureus was 6% (12/125), while 33.6% (42/125) were coagulase-negative staphylococci (CoNS). Among the isolated S. aureus, 75% were resistant to methicillin, while 66.7% of the CoNS were resistant to methicillin. Further, 92% (11/12) of the S. aureus isolates were resistant to erythromycin, and 50% (6/12) were resistant to clindamycin. Among the CoNS, 83% (35/42) were resistant to erythromycin, and 52% (22/42) were resistant to clindamycin. The proportion of inducible macrolides lincosamide streptogramin B resistance (iMLSB), constitutive macrolides lincosamide streptogramin B resistance (cMLSB), and macrolides lincosamide streptgramin B methicillin susceptible (MS) phenotypes among S. aureus isolates was 16.7%, 41.7%, and 33.3%, respectively, and among CoNS was 19%, 35.7%, and 28.6%, respectively. The overall prevalence of iMLSB and cMLSB phenotypes was 18.5% (10/54) and 37% (20/54), respectively. Comparatively, MRSA had more resistance to ciprofloxacin than methicillin-susceptible S. aureus (MSSA) (88.9% vs. 33.3% p = 0.027), while methicillin-resistant coagulase-negative staphylococci (MR-CoNS) had significantly higher resistance to gentamicin (35.7% vs. 7.1% p= 0.005), and trimethoprim-sulfamethoxazole (78.6% vs. 50% p=0.007) than methicillin-susceptible coagulase-negative staphylococci (MS-CoNS). The high prevalence of methicillin and inducible clindamycin resistance in this study points out a potential rise in treatment failures, prolonged hospitalization, and limited treatment options. Thus, emphasizes the importance of antibiotic stewardship and laboratory-guided antibiotic decisions. To address the growing challenge of antibiotic resistance in Tanzania, it is advisable to implement stringent public health measures, including monitoring antibiotic usage, conducting educational initiatives, and raising awareness among patients and healthcare professionals.

Methicillin-resistant Staphylococci in canine pyoderma in Thailand.

Methicillin-resistant Staphylococci (MRS) seriously threatens animal and human health. Repeated antibiotic use allows the bacteria to develop resistance to several antibiotic classes and become multidrug-resistant (MDR). Canine pyoderma, a common skin condition in dogs, is mainly caused by Staphylococci, including MRS. Detecting this infection in all canine populations is crucial to develop a proper preventive plan. This study estimated the prevalence, antibiogram, and risk factors of MRS in canine patients at a referral animal hospital in Khon Kaen, Thailand. Skin swabs and relevant information were collected from 56 client-owned dogs that visited the hospital from September 2019 to September 2020. Staphylococci colonies were subjected to molecular identification and antibiotic susceptibility tests using an automated system (VITEK® 2). These colonies were also genetically identified using multiplex-polymerase chain reaction (PCR) and sequencing. The mecA gene, encoding methicillin resistance, was detected using simplex-PCR. The risk factors of MRS infection and their association with MRS infection were analyzed using logistic regression and the Chi-square test, respectively. The prevalence of MRS was found to be 35.7% (20/56 dogs). By species, methicillin-resistant Staphylococcus pseudintermedius was found in 24 of 104 isolates (23.1%), and all samples were MDR. Receiving systemic antibiotics in the past 6 months was a major risk factor associated with MRS infection (p < 0.05; odds ratio (OR) > 1). In addition to the MRS isolates, the mecA gene was also detected in methicillin-susceptible Staphylococci isolates. This might be because of the high expression of blaI, and mutations in c-di-AMP cyclase DacA, RelA, and Fem proteins. A high prevalence of MRS and MDR was observed in the studied population, which might be potentially due to improper antibiotic use by the owners and horizontal transfer of drug-resistance genes.

Periton Diyalizi İle ilişkili Peritonitlerin İrdelenmesi

Objective: In this study, it was aimed to determine the causative microorganisms isolated in peritonitis attacks in peritoneal dialysis (PD) patients in our hospital and methicilline resistance rate in Staphlococci.&#x0D; Material and methods: 194 patients in the peritoneal dialysis unit of XXXXl Training and Research Hospital, Nephrology Clinic, between January 2009 and 2020, were evaluated retrospectively in terms of peritonitis development, causative microorganisms and methicillin resistance in Stapylococci, which is the most common causative agent. &#x0D; Results: Peritonitis attack developed in 149 out of a total of 194 patients. The causative agent has been isolated in 91 (61%) of the patients who developed peritonitis. When we look at the order of frequency among all microorganisms isolated, methicillin-susceptible Staphylococci (MHS) 59 (44.02%), methicillin-resistant Staphylococci (MRS) 28 (20.89%), Escherichia coli 12 (8.95%), Streptococcus spp 12 (8.95%), Enterobacter spp 7 (5.22%), Pseudomonas spp 4 (2.98%), diphtheroid bacilli 4 (2.98%), Klebsiella spp 2 (1.49%), Acinetobacter spp 1 (0.07%), a total of 129 bacteria, including five fungi were detected. Methicillin resistance rate was 32.18% among Staphylococci, which was found to be the most common causative agent.&#x0D; Conclusion: There is a need for studies with large patient groups to show the agents of peritonitis and the change in the resistance profile these microorganisms. &#x0D; Key words: Peritoneal Dialysis, Peritonitis, Methicillin Resistance

Changing Susceptibility of Staphylococci in Patients with Implant-Based Breast Reconstructions: A Single-Center Experience.

Background and Objectives: Infections and capsular contractures remain unresolved issues in implant-based breast reconstruction. Capsular contractures are thought to be caused by the endogenous flora of the nipple duct. However, little is known about the antibiotic susceptibility of the microorganisms involved. This study aimed to evaluate the composition of endogenous breast flora and its antimicrobial susceptibility in patients with breast cancer. This study will aid in selecting a prophylactic antibiotic regimen for breast reconstruction surgery. Materials and Methods: We obtained bacteriologic swabs from the nipple intraoperatively in patients who underwent implant-based breast reconstruction following nipple-sparing mastectomy between January 2019 and August 2021. Antibiotic susceptibility tests were performed according to the isolated bacteriology. Statistical analysis was performed based on several patient variables to identify which factors influence the antibiotic resistance rate of endogenous flora. Results: A total of 125 of 220 patients had positive results, of which 106 had positive culture results for coagulase-negative Staphylococcus species (CoNS). Among these 106 patients, 50 (47%) were found to have methicillin-resistant staphylococci, and 56 (53%) were found to have methicillin-susceptible staphylococci. The methicillin resistance rate in the neoadjuvant chemotherapy group (56.3%) was significantly higher (OR, 2.3; p = 0.039) than that in the non-neoadjuvant chemotherapy group (35.5%). Conclusions: Based on the results, demonstrating high and rising incidence of methicillin-resistant staphylococci of nipple endogenous flora in patients with breast cancer compared to the past, it is necessary to consider the selection of prophylactic antibiotics to reduce infections and capsular contracture after implant-based breast reconstruction.

1038. In Vitro Activity of Tebipenem, an Orally Available Carbapenem Agent, Against a Collection of Surveillance Gram-Positive Clinical Isolates

BackgroundTebipenem, an orally bioavailable carbapenem administered as a pro-drug, completed a phase 3 clinical trial for evaluating its safety and efficacy for the treatment of complicated urinary tract infection and acute pyelonephritis. The purpose of this study was to investigate the in vitro activity of tebipenem and comparator agents, including ertapenem and meropenem, against a recent collection of Gram-positive isolates associated with clinical infections.MethodsThe susceptibility of 580 Gram-positive organisms were tested, including: methicillin-susceptible Staphylococcus aureus (MSSA, 489 isolates), methicillin-susceptible Staphylococcus epidermidis (MSSE, 31), other methicillin-susceptible coagulase-negative staphylococci (MSCoNS, 29), and vancomycin-susceptible Enterococcus faecalis (31). The isolates were collected primarily from pneumonia in hospitalized patients (498 isolates; 85.9%), urinary tract infections (42 isolates; 7.2%), and bloodstream infections (38 isolates; 6.6%). Organisms were tested using reference broth microdilution methods in a central laboratory. ResultsTebipenem had an MIC90 value of 0.03 mg/L against MSSA and 0.015 mg/L against MSSE isolates. Ertapenem MIC90 values were 8-fold higher against MSSA (MIC90, 0.25 mg/L) and 32-fold higher against MSSE (MIC90, 0.5 mg/L). Tebipenem displayed an MIC90 value of 0.03 mg/L against MSCoNS species other than S. epidermidis. This result was 8- and 32-fold lower than those of meropenem (MIC90, 0.25 mg/L) and ertapenem (MIC90, 1 mg/L), respectively. Tebipenem inhibited all E. faecalis isolates at ≤1 mg/L (MIC90, 1 mg/L), with an MIC90 value at least 2-fold lower than meropenem (MIC90, >1 mg/L) and 16-fold lower than ertapenem (MIC90, >8 mg/L).ConclusionTebipenem displayed potent activity against methicillin susceptible staphylococci, including MSSA, MSSE, and other MSCoNS. Tebipenem in vitro activity was greater than meropenem and ertapenem when tested against E. faecalis. These data indicate that tebipenem may be an option for treating urinary tract infections caused by these organisms or as an empiric option to provide broader coverage against Gram-negative and -positive organisms. Disclosures S J Ryan Arends, PhD, AbbVie (formerly Allergan) (Research Grant or Support)GlaxoSmithKline, LLC (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Nabriva Therapeutics (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Abby L. Klauer, n/a, Cidara Therapeutics, Inc. (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Nicole Cotroneo, Spero Therapeutics (Employee, Shareholder) Ian A. Critchley, Ph.D., Spero Therapeutics (Employee, Shareholder) Rodrigo E. Mendes, PhD, AbbVie (Research Grant or Support)AbbVie (formerly Allergan) (Research Grant or Support)Cipla Therapeutics (Research Grant or Support)Cipla USA Inc. (Research Grant or Support)ContraFect Corporation (Research Grant or Support)GlaxoSmithKline, LLC (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Nabriva Therapeutics (Research Grant or Support)Pfizer, Inc. (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support)

ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF STAPHYLOCOCCUS AUREUS STRAINS IN ISLAMABAD, PAKISTAN

Objective: To investigate the prevalence of S. aureus in hospitalized patients of Islamabad.&#x0D; Study Design: Cross-sectional study.&#x0D; Study Duration: Pakistan Institute of Medical Science, Applied Microbiology and Biotechnology Lab, COMSATS Institute of Information Technology, Islamabad, from Sep 2017 to Sep 2018.&#x0D; Methodology: A total of 500 samples were collected. The isolates were divided into four study groups according to their source of origin i.e. group 1 (dermal group), group 2 (nasal group), group 3 (blood group) and group 4 (urine group). Gram staining, catalase test and DNA se media analysis were done for validation of S. aureus. Disc diffusion test (for antibiotic susceptibility), Oxacillin disc test (to differentiate between methicillin-resistant Staphylococcus aureus and methicillin-susceptible staphylococcus aureus) and minimal inhibitory concentration (for susceptibility to vancomycin), were performed.&#x0D; Results: Degree of the prevalence of staphylococcus aureus was 21%, 17%, 9% and 8% in group 1, 2, 3 &amp; 4 respectively. The overall prevalence of staphylococcus aureus was 19.5% in all isolates. The disc diffusion test showed the descending resistance pattern of isolates i.e. 100, 94, 94, 76, 58, 55, 47, 43, 40 and 37% for penicillin, ciprofloxacin, Kanamycin, erythromycin, tetracycline, oxazolidinone, sulfamethoxazole, doxycycline, clindamycin, and cipoxin respectively. Minimal inhibitory concentration found only one sample resistant at 2ug/l concentration of Vancomycin. Moreover, Oxacillin disc test showed 52% methicillin-susceptibleStaphylococcus aureus while 48.2% methicillin-resistant staphylococcus aureus among all isolates.&#x0D; Conclusion: There is an increase in the frequency of methicillin-resistant staphylococcus aureus. Single vancomycin resistant staphylococcus aureus strain was also isolated.

Knee arthrodesis using a custom modular intramedullary nail in failed, infected knee arthroplasties: A concise follow-up note of 31 cases at a median of 13 years post-arthrodesis

IntroductionKnee arthrodesis utilizes an arthrodesis nail as a salvage technique for infected total knee arthroplasty (TKA), especially when the extensor mechanism is damaged, or the skin is compromised. This implant helps to minimize or prevent leg length discrepancy, while allowing immediate weight bearing without requiring bone fusion. However, there is a risk of infection. Surgical revisions were required in 19% of patients at 50 months’ follow-up in our team's initial 31-patient case series. Since there is little long-term outcome data, we reviewed this same group of patients after a mean of 13 years to determine: (1) the implant's long-term survival, (2) the functional outcomes, (3) the microbiological changes in revision cases. HypothesisThe long-term survival of knee arthrodesis using an arthrodesis nail for failed infected TKA is acceptable. Material and methodsThirty-one patients operated on between January 2005 and December 2008 were retrospectively included in the initial study. The functional outcomes consisted of pain on a visual analog scale (VAS), neuropathic pain (DN4) and the Oxford Knee Score. All surgical revisions were documented with repeat microbiology samples. ResultsThe median follow-up time was 13.1 years [11.5–13.5]. No mechanical failure (implant failure or aseptic loosening) was observed. Eight patients were re-operated on due to new infections. The nail had to be removed in five of these patients. None of the patients required an amputation. Among the eight patients who were re-operated on, only two (25%) had been re-operated on since the initial study and underwent a two-stage arthrodesis revision. At 10 years, the cumulative incidence of surgical revision at the knee was 26% [95% CI: 12%–43%] and 16% [95% CI: 5.7%–31%] for an implant change. Six (75%) of the re-operated patients had their revision within the first 72 months of the initial TKA, while 4 (50%) had it within the first 26 months. Among the 15 patients who were still alive, the median Oxford Knee Score was 17/48 [12–28]. At the final assessment, the median pain level was 0 [0–5], although 4 of the 10 analyzable patients (of the 15 living patients, 3 had a cognitive impairment and 2 refused to participate) had neuropathic pain and pain on VAS of 3/10. The microbiologic findings were the same during the surgical revision in five of the eight re-operated patients (62%); however, one patient who had a Staphylococcus aureus infection had acquired a resistance to methicillin. In one patient, only one of the two bacteria identified initially was still present (methicillin-susceptible Coagulase-negative staphylococci [CNS]) and while in two patients, the infectious agent changed completely (shift from Gram-negative bacilli to methicillin-susceptible CNS, and the opposite for the other patient). DiscussionKnee arthrodesis with a custom modular intramedullary nail is a viable limb salvage option in failed infected TKA cases with long-term survival, and it is comparable to other arthrodesis techniques. In most cases, recurrence of the infection occurred in the short term (<72 months). Later recurrences of the infection (>72 months) were rarer and were found in only two of our patients (6%). There were no mechanical failures. Level of evidenceIV; Retrospective cohort study.

Antibiotics in Bone Cements Used for Prosthesis Fixation: An Efficient Way to Prevent Staphylococcus aureus and Staphylococcus epidermidis Prosthetic Joint Infection.

Prosthetic joint infections (PJIs) are one of the most frequent reasons for arthroplasty revision. These infections are mostly associated with the formation of biofilm, notably by staphylococci, such as Staphylococcus aureus and Staphylococcus epidermidis. To minimize the rates of PJIs following primary or revision total joint arthroplasty, antibiotic-loaded bone cements (ALBCs) can be used for prosthesis fixation. However, its use is still debated. Indeed, various studies reported opposite results. In this context, we aimed to compare the prophylactic anti-biofilm activity of ALBCs loaded with two antibiotics with ALBC loaded with only one antibiotic. We compared commercial ready-to-use cements containing gentamicin alone, gentamicin plus vancomycin, and gentamicin plus clindamycin to plain cement (no antibiotic), investigating staphylococcal biofilm formation for 10 strains of S. aureus and S. epidermidis with specific resistance to gentamicin, vancomycin, or clindamycin. Firstly, we performed disk diffusion assays with the elution solutions. We reported that only the cement containing gentamicin and clindamycin was able to inhibit bacterial growth at Day 9, whereas cements with gentamicin only or gentamicin and vancomycin lost their antibacterial activity at Day 3. Then, we observed that all the tested ALBCs can inhibit biofilm formation by methicillin-susceptible staphylococci without other antibiotic resistance ability. Similar results were observed when we tested vancomycin-resistant or clindamycin-resistant staphylococci, with some strain-dependent significant increase of efficacy for the two antibiotic ALBCs when compared with gentamicin-loaded cement. However, adding vancomycin or clindamycin to gentamicin allows a better inhibition of biofilm formation when gentamicin-resistant strains were used. Our in vitro results suggest that using commercially available bone cements loaded with gentamicin plus vancomycin or clindamycin for prosthesis fixation can help in preventing staphylococcal PJIs following primary arthroplasties, non-septic revisions or septic revisions, especially to prevent PJIs caused by gentamicin-resistant staphylococci.

Prolonged cefazolin course for treatment of methicillin susceptible staphylococcus species infections and the impact on the emergence of multidrug-resistant bacteria during cloxacillin shortage

ObjectivesTo describe the efficacy and safety of prolonged cefazolin course for Staphylococcus infection and the emergence of multidrug-resistant bacteria carriage after treatment. MethodsMonocentric retrospective cohort study of patients hospitalized for blood stream infections (BSI) and osteoarticular infections (OAI) by methicillin susceptible staphylococcal species treated with cefazolin from January 2015 to July 2017. Rectal and nasal swabs were performed at cefazolin initiation and end of treatment to detect respectively methicillin resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL) producing bacteria. ResultsFifty-eight patients were included, 41 had a bacteremia including 22 endocarditis and 22 OAI. Mean duration of treatment was 21.5 days at a mean daily dose of 6.5g/d. Fifty-five (94.5%) received combination therapy. Fifty-two (89.7%) of patients achieved bacteriological cure. Four patients were ESBL carriers at inclusion. No additional ESBL or MRSA were detected by end of treatment. ConclusionCefazolin appears as an effective and safe treatment for BSI or osteoarticular infection and does not appear to select MRSA or ESBL.

Cefazolin inoculum effect among methicillinsusceptible Staphylococcus aureus isolated from patients with skin infections

Objective. To evaluate frequency and intensity of cefazolin inoculum effect among methicillin-susceptible staphylococci isolated from patients with skin infections. Materials and Methods. A total of 80 methicillin susceptible isolates of Staphylococcus aureus were identified by cefoxitin disk-diffusion test and negative results of real-time PCR for mecA gene. Inoculum effect was measured by broth microdilution test with two inocula with concentrations of 5 × 105 CFU/mL and 5 × 107 CFU/mL. The disk-diffusion test with cefoxitin was also performed. Penicillin susceptibility was determined by disk-diffusion method. Beta-lactamase blaZ gene was identified by real-time PCR. Results. The frequency of cefazolin inoculum effect in tested isolates was 30% which is consistent with data from different countries. The MIC values for concentrated inoculum reached CLSI breakpoint for cefazolin resistance in 2.5% of isolates. The isolates with inoculum effect and those without it had the similar MIC values for cefazolin in broth microdilution test for standard inocula and similar diameters of inhibition zone in disk-diffusion test with cefazolin. Penicillin resistance was more frequent in inoculum effect-positive isolates. Beta-lactamase activity is considered as a main cause of cefazolin inoculum effect in staphylococci. The beta-lactamase blaZ gene was identified in the majority of isolates with cefazolin inoculum effect, but it was also prevalent among inoculum effect-negative isolates. Conclusions. Up to 30% of MSSA isolates from skin lesions in dermatological patients from SaintPetersburg are positive for cefazolin inoculum effect. Those isolates are usually characterized by penicillin resistance. Most of the cefazolin inoculum effect-positive isolates also carry beta-lactamase blaZ gene.

Bacterial strains colonizing the sensor electrodes of a continuous glucose monitoring system in children with diabetes

IntroductionThe higher frequency of infections in diabetic patients is caused by a hyperglycemic environment, which promotes immune dysfunction. People with diabetes are more prone to skin infections.A continuous glucose monitoring (CGM) system provides information on changes in blood glucose (BG) levels throughout the day. Its use facilitates optimal therapeutic decisions for a diabetic patient. One of the factors limiting the use of CGM is inflammation at the insertion site.Aim of the studyThe aim of the study was the microbiological identification of the bacterial strains which are found on CGM sensor electrodes.Material and methodsWe performed microbiological tests on patients′ CGM Enlite Medtronic electrodes, which were removed after 6 days of usage according to the manufacturer′s instructions. 31 sensors were examined from 31 children (14 girls) aged from 0.5 to 14.6 years. The microbiological analysis was routinely performed at the Department of Children’s Diabetology Medical University of Silesia in Katowice, Poland.Results12 (39%) of the electrodes were colonized. In 11 (92%) cases the electrodes were colonized by one bacteria strain. 7 times methicillin-sensitive coagulase negative staphylococcus (MSCNS) was detected. We also found one case of Klebsiella pneumoniae, Ochrobactrum tritici, Bacillus sonorensis and methicillin-resistant coagulase-negative Staphylococci (MRCNS) colonization. One electrode was colonized by the mixed flora Enterococcus faecalis, methicillin-susceptible coagulase-negative Staphylococci (MSCNS), Pseudomonas stutzeri, methicillin-susceptible Staphylococcus aureus (MSSA). The median HbA1c in the group with colonization of electrodes was 6, 85% (6, 3–7, 6%) versus 6, 3% (5, 8–7, 5%) in the group without colonization. The median BMI in the group with colonization of the electrodes was 17.10 kg/m2 (16.28–18.62 kg/m2) versus 15.98 kg/m2 (15.14–17.96 kg/m2) in the group without colonization. Statistically, significantly more frequently electrodes are colonized in older children (median age in the group with colonization of electrodes 11.43 years (6.52–12.27 years), without colonization 8.42 years. (3.098–9.375 years); (p = 0.033).ConclusionsIt seems that older children are more likely to have their sensor electrode colonized by bacterial strains.

Activity of ceftaroline versus ceftobiprole against staphylococci and pneumococci in the UK and Ireland: analysis of BSAC surveillance data.

Ceftaroline and ceftobiprole inhibit most MRSA and MDR pneumococci. Few direct comparisons of their activity have been published, but in several years (2008, 2013, 2017 and 2018) both were tested in parallel in the BSAC Resistance Surveillance Programme, giving paired results. These are reviewed. Isolates included were bloodstream Staphylococcus aureus [n = 1884 (MRSA, n = 234)], bloodstream CoNS (n = 813; 574 methicillin resistant), and bloodstream (n = 852) and respiratory (n = 670) Streptococcus pneumoniae. MICs were determined by BSAC agar dilution and reviewed against EUCAST breakpoints; S. aureus breakpoints were assumed for CoNS. Ceftaroline MICs were mostly 2-fold lower than those of ceftobiprole, but, for all groups, MICs of both agents were strongly inter-related. Methicillin-susceptible staphylococci were universally susceptible to both agents; all MRSA were susceptible to ceftobiprole, whereas 10/234 had intermediate/high-dose susceptibility to ceftaroline. Among methicillin-resistant CoNS, 88% were susceptible to both agents, but reduced ceftaroline susceptibility and ceftobiprole resistance were frequent (65%) among methicillin-resistant Staphylococcus haemolyticus. One S. pneumoniae was resistant to both ceftaroline (MIC 0.5 mg/L) and ceftobiprole (MIC 1 mg/L) and seven others were only resistant to ceftobiprole (MIC 1 mg/L); seven of these eight pneumococci belonged to serotype 19A or 19F. No time trend in susceptibility was seen for either cephalosporin. Ceftaroline and ceftobiprole have similarly good activity against staphylococci and pneumococci. Therapeutic choices between these agents should be predicated on other differentiating factors, including licensed indications, clinical experience and need for Gram-negative coverage.

Spa gene-based molecular typing of nasal methicillin-susceptible staphylococcus aureus from patients and health-care workers in a dialysis center in southeast Iran

ABSTRACTStaphylococcus aureus is an important infectious agent in hemodialysis patients. This study was conducted to determine the frequency of S. aureus nasal carriage in hemodialysis patients (HD) and health-care workers (HCW) at the main dialysis center of Bam city, located in southeast of Iran. In this cross-sectional study, a total of 52 nasal swabs were obtained from health-care workers and hemodialysis patients to detect methicillin-sensitive S. aureus (MSSA) isolates. The resistance to different antibacterial agents was determined by disk diffusion method. Also, Panton-Valentine Leukocidin (PVL) – encoding gene as well as Staphylococcal protein A (spa) type were determined. The nasal carriage rate of S. aureus was found to be 24.4% and 18.8% in patients on hemodialysis and health-care workers, respectively. Among identified isolates, no methicillin-resistant S. aureus (MRSA) was found. Only two MSSA isolates (16.7%) were resistant to trimethoprim/sulfamethoxazole. One isolate (8.6%) was positive for pvl gene. Moreover, 8 spa types were found. According to BURP analysis, six out of the 12 S. aureus isolates (50%) belonged to the same clone, indicating a prevalence of a major clone among MSSA in carriage, including patients and HCW. Mupirocin is still the appropriate drug for reducing nasal colonization in our setting. Accumulation of isolates from patients and staff in one spa clonal complex is alarming for the necessity of more serious infection control in this center. Therefore, it is necessary to screen patients and health-care workers as a health priority, in order to prevent cross transmission.

In vitro Susceptibilities of Methicillin-Susceptible and Resistant Staphylococci to Traditional Antibiotics Compared to a Novel Fluoroquinolone

BackgroundTo assess the in-vitro efficacy of delafloxacin, a new fourth generation fluoroquinolone, against Staphylococcus vitreous isolates from patients with clinically diagnosed endophthalmitis. This is the first investigation of delafloxacin in ocular tissues.MethodsIntravitreal isolates of culture-proven S. aureus and S. epidermidis were identified between 2014 and 2018. Minimum inhibitor concentrations (MIC) were determined using ETEST strips. The antibiotic susceptibilities were tested against a panel of drugs including glycopeptides such as vancomycin, as well as traditional and newer fluoroquinolones (levofloxacin, moxifloxacin, and delafloxacin).ResultsOf 45 total isolates identified between 2014 and 2018, 13% (6) were methicillin-resistant S. aureus (MRSA), 9% (4) were methicillin-sensitive S. aureus (MSSA), 53% (24) were methicillin-resistant S. epidermidis (MRSE), and 24% (11) were methicillin-sensitive S. epidermidis (MSSE). Among the fluoroquinolones, resistance rates were 61% for levofloxacin, 50% for moxifloxacin, and 12% for delafloxacin. Inter-class comparisons between delafloxacin and the two other fluoroquinolones demonstrated higher Gram-positive susceptibility to delafloxacin (p < 0.01). MIC90 values were lowest for delafloxacin (1.0 μg/mL) compared to levofloxacin (8.0 μg/mL) and moxifloxacin (8.0 μg/mL). Vancomycin was 100% effective against all isolates with MIC90 value of 0.75 μg/mL.ConclusionCompared to levofloxacin and moxifloxacin, the newer fluoroquinolone delafloxacin demonstrated the lowest MICs values and lowest rates of resistance for Gram-positive in-vitro S. epidermidis and S. aureus vitreous isolates.

MOLECULAR TYPING OF METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS AUREUS (MSSA), ISOLATED FROM MONKEYS, BASED ON COAGULASE GENE POLYMORPHISM

Staphylococcus aureus is a very dangerous microorganism that causes more than 100 nosological forms of disease in humans and animals, including pneumonia, skin and soft tissue infections, food toxicoinfections, wound abscess, etc. Numerous studies on genotyping Staphylococcus aureus, isolated from humans, food and bovine mastitis have been carried out. The lack of information on the genotyping of these pathogens detected in monkeys living in captivity served as a stimulus to conduct a similar research, since staphylococcal infections in the primates are widespread. The present study is devoted to the study of the polymorphism of a variable region of the coagulase gene and to the typing of Staphylococcus aureus isolates from monkeys of different species kept at Adler monkey farm. 115 Staphylococcus aureus isolates were studied using phenotypic and molecular genetic methods. Genotyping was performed using PCR, real-time PCR and PCR with subsequent restriction fragment length polymorphism analysis (PCR-RFLP). A real-time PCR analysis allowed to classify all Staphylococcus aureus as methicillin-susceptible staphylococci (MSSA). After amplification of a variable region of the coagulase gene, 4 types of amplicons of 600, 700, 800, and 900 bp were generated. This data demonstrates structural differences of this gene in the studied isolates. The coagulase gene of 900 bp prevailed. The use of the Cfo1 endonuclease allowed to identify 23 different restriction profiles of the coa gene, but only three of them predominated. Staphylococcus aureus bacteria with seven types of coagulase gene were found only in the lungs of monkeys that died of pneumonia. The results obtained suggest that these isolates have tropism for lung tissue. Among Staphylococcus aureus isolated from pneumonia cases, isolates with three types of the coa gene prevailed. Staphylococcus aureus of eleven types of coagulase gene can be attributed to the invasive isolates, since they were detected in the tissues of various organs. Staphylococcal infection in monkeys kept at the monkey farm is caused by genotypically heterogeneous population of Staphylococcus aureus.

Daptomycin-Tobramycin Cement Beads have Lethal Local Antibacterial Effect in Resistant Periprosthetic Joint Infections.

BackgroundResistant periprosthetic joint infection (PJI) can be a devastating complication of surgery and is difficult to treat. We attempted to identify the utility of Daptomycin/Tobramycin-impregnated polymethylmethacrylate (PMMA) beads in resistant PJIs.MethodsCharts of patients with hip or knee PJI at a single academic medical center, with surgeries performed from May 2008 through May 2018, were reviewed retrospectively. The diagnosis of PJI was consistent with the Musculoskeletal Infection Society recommendations. Prosthetic joints underwent radical anterior-posterior synovectomy and placement of antibiotic cement beads in the infected joint. Clinical cure rate and local intraarticular antibiotic concentration were measured.ResultsForty-four patients experienced 53 episodes of PJI, requiring 88 surgeries. There was a fairly even split between hip and knee PJI. The cure rate was 92% (11/12) for patients who had any infection with methicillin-resistant staphylococci during the evaluation period, compared with 62% (13/21) for patients with methicillin-susceptible Staphylococci. On days one and seven, the addition of tobramycin increased daptomycin concentrations by 47% and 3374%, respectively, for beads made onsite compared to elution of daptomycin alone. Elution increased by 44% and 8394%, respectively, for commercial beads compared to beads fabricated onsite.ConclusionsDaptomycin-Tobramycin-loaded PMMA beads are safe and powerful bactericidal agents in prosthetic joint infections.

Staphylococcus aureus versus Staphylococcus epidermidis in periprosthetic joint infection—Outcome analysis of methicillin-resistant versus methicillin-susceptible strains

Periprosthetic joint infections (PJIs) are a major complication in total joint arthroplasty. Staphylococcus aureus and coagulase-negative staphylococci are known to cause the majority of all PJIs. This study aimed to analyze the eradication rates of S. aureus and S. epidermidis with methicillin susceptibility and methicillin resistance in a 2-stage therapy algorithm. Seventy-four patients with PJI caused by methicillin-resistant S. aureus (MRSA), methicillin-resistant coagulase-negative staphylococci (MRSE), methicillin-susceptible S. aureus (MSSA), and methicillin-susceptible coagulase-negative staphylococci (MSSE) were included, and the outcome was analyzed retrospectively. After a minimal follow-up of 2 years, n = 56 patients (75.7%) were definitively free of infection. The analysis revealed significant differences between the groups, with eradication rates as follows: MSSA (92.6%), MSSE (95.2%), MRSA (80%), and MRSE (54.2%). MRSE showed a significantly lower rate of patients graded as “definitively free of infection” as compared to patients with infections caused by MSSA, MSSE, and MRSA.