Clinical Characteristics of Methicillin-resistant Coagulase-negative Staphylococcal Bacteremia in a Tertiary Hospital

Rise in the Pathogenic Status of Coagulase-Negative Staphylococci Causing Bloodstream Infection

BACKGROUND

Coagulase-negative staphylococci (CoNS) are one of the frequently isolated bacteria from blood cultures. Since they are part of the normal skin flora, they were previously considered contaminants. But now, they can be considered as established pathogens causing bloodstream infection (BSI). This study aims to estimate the prevalence of CoNS in BSI cases.

METHODS

This study was conducted at the Microbiology Department, All India Institute of Medical Sciences (AIIMS), Raipur, India, for eight months (January 2022 to August 2022). Data were collected retrospectively from medical and laboratory records. Paired blood cultures from 5085 clinically suspected sepsis cases were subjected to aerobic culture for five days in the BacT ALERT 3D system. Pathogenicity was established after recovery of CoNS from paired blood cultures of symptomatic patients.

RESULTS

CoNS were isolated from 2.35% of patients, the most common species being Staphylococcus haemolyticus (51.67%). About 90% of isolates were methicillin-resistant. All the isolates were susceptible to linezolid, teicoplanin, and vancomycin, except one isolate of S. haemolyticus which was intermediate to vancomycin. Minimum inhibitory concentration (MIC) 50 and MIC 90 for vancomycin were 1 ug/ml and 2 ug/ml, respectively.  Conclusion: Paired blood cultures are necessary to determine the pathogenicity of CoNS in BSI cases. A high prevalence of methicillin resistance, accompanied by high resistance rates to other non-beta lactam antibiotics, warrants the strict implementation of antimicrobial stewardship practices.

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

INTRODUCTION

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 isolates used as a control.

METHODS

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.

RESULTS

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.

CONCLUSIONS

The VCM MICs of Staphylococcus species from orthopedic infections were higher than those of respiratory samples, particularly MRCNS from implant-related samples.

Identification of staphylococcal cassette chromosome mec in Staphylococcus aureus and non-aureus staphylococci from dairy cattle in Belgium: Comparison of multiplex PCR and whole genome sequencing

The present study compared multiplex PCR (mPCR) and Whole Genome Sequencing (WGS) using the SCCmecFinder database to identify the Staphylococcal Cassette Chromosome (SCC) mec in five Staphylococcus aureus (SA) and nine non-aureus staphylococci (NAS) isolated from dairy cattle. mPCR identified an SCCmecIV in four SA and one NAS, but could not differentiate between SCCmecII and IV in the fifth SA, that all harbored the mecA gene and were phenotypically resistant to cefoxitin. SCCmecFinder confirmed the presence of an SCCmecIVc(2B) in four SA and of the SCCmecIVa(2B) in the fifth SA and the one NAS. Both methods also detected one untypeable SCCmec in another cefoxitin-resistant NAS harboring the mecA gene and a pseudo SCCmec in one cefoxitin-sensitive NAS harboring one mecC-related gene. No SCCmec elements were identified either in one cefoxitin-sensitive NAS harboring the mecA2 gene, or in five NAS (one resistant and four sensitive to cefoxitin) harboring the mecA1 gene. SCCmecFinder could even not identify the presence of any mecA1 gene in these five NAS, whose presence was nevertheless confirmed by ResFinder. The conclusions of this study are: (i) mPCR and WGS sequencing using SCCmecFinder are complementary methodologies to identify SCCmec; (ii) SCCmecFinder and ResFinder to a lesser extent cannot identify all mec gene allotypes; (iii) a specific classification of the SCCmec in NAS would be epidemiologically helpful; (iv) presence of a mecA gene and a complete SCCmec is linked to cefoxitin resistance, whereas presence of other mec genes and of pseudo or no SCCmec is not.

Changes of the microbiological spectrum and antibiotic resistance pattern in postoperative spinal implant infections with multiple culture-positive revision surgeries

BACKGROUND CONTEXT

In severe cases of postoperative spinal implant infections (PSII) multiple revision surgeries may be needed. Little is known if changes in the microbiological spectrum and antibiotic resistance pattern occur between revision surgeries.

PURPOSE

Analysis of the microbiological spectrum and antibiotic resistance pattern in patients with multiple revision surgeries for the treatment of PSII STUDY DESIGN: Retrospective database analysis.

PATIENT SAMPLE

Between 01/2011 and 12/2018, 103 patients underwent 248 revision surgeries for the treatment of PSII. Twenty patients (19.4%) who underwent multiple revision surgeries for PSII were included in this study.

OUTCOME MEASURES

Microbiological spectrum, antibiotic resistance pattern.

METHODS

A retrospective analysis of a prospectively maintained single center spine infection database was performed with a minimum follow-up of 3 years. Overall, 20 patients (six male/14 female) underwent 82 revisions for PSII (median 3; range 2-12). There were 55 of 82 (67.1%) procedures with a positive microbiological result. Microbiological analysis was performed on tissue and implant sonication fluid. Changes in microbial spectrum and antibiotic resistance pattern between surgeries were evaluated using Chi-Square and Fisher's exact test.

RESULTS

In total, 74 microorganisms (83.3% gram-positive; 10.8% gram-negative) were identified. The most common microorganisms were Staphylococcus epidermidis (18.9%) and Cutibacterium acnes (18.9%). All S. epidermidis identified were methicillin-resistant (MRSE). Overall, there were 15 of 55 (27.3%) polymicrobial infections. The microbiological spectrum changed in 57.1% (20/35) between the revision stages over the entire PSII period. In 42.9% (15/35) the microorganism persisted between the revision surgeries stages. Overall, changes of the antibiotic resistance pattern were seen in 17.4% (8/46) of the detected microorganisms, comparing index revision and all subsequent re-revisions. Moreover, higher resistance rates were found for moxifloxacin and for ciprofloxacin at first re-revision surgery compared with index PSII revision. Resistances against vancomycin increased from 4.5% (1/23) at index PSII revision to 7.7% (2/26) at first re-revision surgery.

CONCLUSIONS

Changes of the microbiological spectrum and the resistance pattern can occur in patients with severe PSII who require multiple revision surgeries. It is important to consider these findings in the antimicrobial treatment of PSII. The microbiological analysis of intraoperative tissue samples should be performed at every revision procedure for PSII.

Efficiency of Pyroligneous Extract from Jurema Preta (Mimosa tenuiflora [Willd.] Poiret) as an Antiseptic in Cats (Felis catus) Subjected to Ovariosalpingohysterectomy

Simple Summary

The pyroligneous extract from Mimosa tenuiflora was used as an antiseptic in cats. The objective of this study was to analyze the action of 20% pyroligneous extract from M. tenuiflora as an antiseptic for surgical wounds of cats subjected to ovariohysterectomy. In addition to the absence of cytotoxicity, the number of bacteria was reduced after treatment. Tissue dehiscence, hyperemia, edema, crust, and secretions were not observed. Thus, the pyroligneous extract of M. tenuiflora has potential as a natural antiseptic alternative.

Abstract

Pyroligneous extract of Jurema preta (Mimosa tenuiflora [Willd.] Poiret) was evaluated for its efficacy as a cutaneous antiseptic in cats (Felis catus) that were subjected to ovariosalpingohysterectomy. For this purpose, 30 cats without a defined breed were sterilized and divided into two groups. The first group was the positive control, treated with 0.5% chlorhexidine-alcohol solution, and the second group was treated with 20% pyroligneous extract of M. tenuiflora. Regardless of age and sex, all animals had visible healing at similar times. A significant reduction in bacterial growth was observed in animals treated with the extract, and no cytotoxicity was observed in the feline epithelial cells. In addition, surgical wounds of cats treated with M. tenuiflora extract exhibited improved healing. On agar plates, treatment with both chlorhexidine and M. tenuiflora extract resulted in the inhibition zones for all bacterial strains isolated from surgical wounds. Therefore, M. tenuiflora extract is demonstrated to have antiseptic effects on the surgical wounds of cats undergoing ovariosalpingohysterectomy.

Microbial Distribution and Antibiotic Susceptibility of Bloodstream Infections in Different Intensive Care Units

Background: Bloodstream infection (BSI) is an increasing public health concern worldwide, representing a serious infection with significant morbidity and mortality, especially in children and the elderly. The predominant microbial distribution and antibiotic susceptibility were investigated among BSIs in the different intensive care units (ICUs)—pediatric ICU (PICU), surgical ICU (SICU), cardiac ICU (CICU), respiratory ICU (RICU), and geriatric ICU (GICU)—in order to achieve more efficient and appropriate therapies for patients in various ICUs.

Methods: In this retrospective cross-sectional study, the blood specimens were collected from five different ICUs of Peking University First Hospital and comprehensive ICU of Miyun Teaching Hospital (Miyun ICU) before antimicrobial treatment from 2017 to 2020. Microorganism cultures of the blood samples were conducted, and positive cultures were tested for type of pathogens and drug susceptibility.

Results: The prevalence of BSIs was the highest in the Miyun ICU (10.85%), followed by the RICU (9.48%) and the PICU (8.36%). The total prevalence of Gram-positive bacterial strains (especially Staphylococcus spp. and Enterococcus spp.) in the PICU (44.55%), SICU (57.58%), CICU (55.00%), GICU (49.06%), and Miyun ICU (57.58%) was higher than that of Gram-negative bacteria. The major bacterial strain was Acinetobacter baumannii in the PICU (21.82%); Klebsiella pneumoniae in the SICU (12.88%), CICU (30.00%), and RICU (30.39%); Escherichia coli in the GICU (20.75%); and Staphylococcus epidermidis (18.18%) in the Miyun ICU. Staphylococcus hominis of BSIs remained highly susceptible (>70%) to gentamicin, linezolid, daptomycin, teicoplanin, vancomycin, tigecycline, and rifampicin in all the ICUs. Its antibiotic sensitivity to levofloxacin was moderate in the PICU and CICU, but mild (<30%) in the SICU, RICU, and GICU. K. pneumoniae was highly susceptible to doxycycline, minocycline, and tigecycline in all the ICUs except the RICU, and its antibiotic sensitivity to imipenem, meropenem, amikacin, ciprofloxacin, and levofloxacin was high/moderate in the PICU, CICU, GICU, and Miyun ICU, but mild in the SICU and RICU.

Conclusion: The current study demonstrated the distribution of prevalent microorganisms, and their antimicrobial susceptibility exhibited a high divergence among BSIs in different ICUs from a tertiary hospital and an outer suburban hospital in Beijing. Therefore, different antibiotic therapies for various wards and distinct age groups (especially between pediatric and elderly patients) should be considered to control the emergence and spread of highly antibiotic-resistant infections.

Update on activity of dalbavancin and comparators against clinical isolates of Gram-positive pathogens from Europe and Russia (2017-2018), and on clonal distribution of MRSA

BACKGROUND

Gram-positive pathogens remain a major cause of healthcare- and community-associated infections. In particular, the dissemination of methicillin-resistant staphylococci, as methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE), have significantly reduced the therapeutic options, making the management of these infections even more challenging. Dalbavancin is a second-generation lipoglycopeptide approved for the treatment of moderate to severe acute bacterial skin and skin structure infections (ABSSSIs) caused by Gram-positive organisms, showing a bactericidal effect and a low propensity towards the selection of resistance over time.

AIM

This study aimed to evaluate the antimicrobial activity of dalbavancin and other comparators against recent clinical isolates of Gram-positive pathogens obtained from different sources and from several European countries, including countries of southern and eastern Europe and Russia, where resistance rates are typically high. This study also aimed to describe the clonal relationship of MRSA strains circulating in southern and eastern Europe and Russia.

RESULTS

A total of 1478 isolates were collected. Study results demonstrated the excellent and stable activity of dalbavancin against Gram-positive microorganisms, including MRSA. Interestingly, dalbavancin has retained unaltered MIC₅₀ and MIC₉₀ values over the years and seemed to have a low propensity in selecting resistance mechanisms.

CONCLUSIONS

Our data supported the potential efficacy of dalbavancin against Gram-positive bacteria and uncommon Gram-positive pathogens in patients with ABSSSIs. Of note, few CoNS isolates were resistant to dalbavancin and susceptible to vancomycin, pointing out the importance of testing the susceptibility to dalbavancin before its administration for CoNS infections.

Determination of the frequency, species distribution and antimicrobial resistance of staphylococci isolated from dogs and their owners in Trinidad

The close contact between humans and their dogs can lead to the commingling of staphylococci and the exchange of mobile genetic elements encoding antimicrobial resistance. The objectives of this study were to determine the species distribution and antimicrobial resistance patterns of staphylococci colonizing canine pets and their owners in Trinidad. Staphylococci were isolated from canine pets and their owners and identified using MALDI-TOF mass spectrometry. Antimicrobial susceptibilities were determined using the Kirby-Bauer disc diffusion method against seven classes of antimicrobial agents. A total of 440 staphylococci were isolated from 112 canine pets and their owners, 53.4% were from canine pets and 46.6% were from owners. Twenty-four species were detected, of which, most isolates (32.5%) belonged to the Staphylococcus intermedius group (SIG). S. sciuri was the most common species of coagulase-negative staphylococci (CoNS) comprising 22.3% of all isolates. Antimicrobial resistance was highest against commonly used antimicrobials, such as penicillin (51.4%), tetracycline (26.1%) and trimethoprim/sulfamethoxazole (18.6%). These antimicrobials also comprised the most common multidrug resistance (MDR) combination. Overall, 19.1% of isolates displayed multidrug resistance. No methicillin-resistant Staphylococcus aureus (MRSA) isolates were detected. However, methicillin resistance was detected in 13.3% and 15.1% of coagulase-positive staphylococci (CoPS) and the CoNS+CoVS (combined CoNS and coagulase-variable staphylococci) group respectively. The presence of methicillin-resistant staphylococci is worrisome because there is the potential for the transfer of these strains between dogs and humans. These strains may act as a reservoir of resistance genes.

Impact of duration of antibiotic therapy in central venous catheter-related bloodstream infection due to Gram-negative bacilli

BACKGROUND

A progressive increase in the incidence of catheter-related bloodstream infection (CRBSI) due to Gram-negative bacilli (GNB) has been reported. Current guidelines recommend antibiotic treatment for at least 7-14 days, although the supporting evidence is limited.

METHODS

We performed a retrospective single-centre study including all patients with a definite diagnosis of GNB CRBSI from January 2012 to October 2018 in which the central venous catheter (CVC) was removed. The occurrence of therapeutic failure [clinical failure (persistence of symptoms and laboratory signs of infection), microbiological failure (persistent bacteraemia or relapse) and/or all-cause 30 day mortality] was compared between episodes receiving short [≤7 days (SC)] or long courses [>7 days (LC)] of appropriate antibiotic therapy following CVC removal.

RESULTS

We included 54 GNB CRBSI episodes with an overall rate of therapeutic failure of 27.8% (15/54). Episodes receiving SC therapy were more frequently due to MDR GNB [60.9% (14/23) versus 34.5% (10/29); P = 0.058] and had higher Pitt scores [median (IQR) 1 (0-4) versus 0 (0-2); P = 0.086]. There were no significant differences in the rate of therapeutic failure between episodes treated with SC or LC therapy [30.4% (7/23) versus 27.6% (8/29); OR 1.15; 95% CI 0.34-3.83; P = 0.822]. The use of SCs was not associated with increased odds of therapeutic failure in any of the exploratory models performed.

CONCLUSIONS

The administration of appropriate antibiotic therapy for ≤7 days may be as safe and effective as longer courses in episodes of GNB CRBSI once the CVC has been removed.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host: An Update

This article reviews antibiotic resistance and treatment of bacterial infections in the growing number of patients who are immunocompromised: solid organ transplant recipients, the neutropenic host, and persons with human immunodeficiency virus and AIDS. Specific mechanisms of resistance in both gram-negative and gram-positive bacteria, as well as newer treatment options are addressed elsewhere and are only briefly discussed in the context of the immunocompromised host.

Virulence Factors in Staphylococcus Associated with Small Ruminant Mastitis: Biofilm Production and Antimicrobial Resistance Genes

Small ruminant mastitis is a serious problem, mainly caused by Staphylococcus spp. Different virulence factors affect mastitis pathogenesis. The aim of this study was to investigate virulence factors genes for biofilm production and antimicrobial resistance to β-lactams and tetracyclines in 137 staphylococcal isolates from goats (86) and sheep (51). The presence of coa, nuc, bap, icaA, icaD, blaZ, mecA, mecC, tetK, and tetM genes was investigated. The nuc gene was detected in all S. aureus isolates and in some coagulase-negative staphylococci (CNS). None of the S. aureus isolates carried the bap gene, while 8 out of 18 CNS harbored this gene. The icaA gene was detected in S. aureus and S. warneri, while icaD only in S. aureus. None of the isolates carrying the bap gene harbored the ica genes. None of the biofilm-associated genes were detected in 14 isolates (six S. aureus and eight CNS). An association was found between Staphylococcus species and resistance to some antibiotics and between antimicrobial resistance and animal species. Nine penicillin-susceptible isolates exhibited the blaZ gene, questioning the reliability of susceptibility testing. Most S. aureus isolates were susceptible to tetracycline, and no cefazolin or gentamycin resistance was detected. These should replace other currently used antimicrobials.

Coagulase negative Staphylococcus bacteremia in hematopoietic stem cell transplant recipients: Clinical features and molecular characterization

The purpose of our study was to investigate the epidemiology of coagulase negative staphylococci (CoNS) responsible for bacteremia in hematopoietic stem cell transplant (HSCT) recipients and to determine the prevalence and the genetic background of methicillin resistance. The prevalence of CoNS bacteremia was 7.4% (54/728), higher in allograft (10.7%) than in autograft (4.7%) recipients. A sepsis or a septic shock were observed in 9% of cases. No deaths were attributable to CoNS bacteremia. The methicillin resistance rate was 81%. All MR-CoNS, harbored mecA gene and 90% were typeable with SCCmec typing using PCR amplification. The SCCmec type IV was the most frequent (44%). Clonal dissemination of MR- Staphylococcus epidermidis strains was limited. Our study showed a low prevalence and favorable outcome of CoNS bacteremia in HSCT recipients with limited clonal diffusion. However, they were associated with a significant rate of severe infections and a high rate of methicillin resistance, mediated by SCCmec IV element in most cases.

Comparison of the Staphylococcal Chromosome Cassette (SCC) mec in Methicillin-Resistant Staphylococcus aureus (MRSA) and Non-aureus Staphylococci (MRNAS) from Animals and Humans

Methicillin-resistant Staphylococcus aureus (MRSA) and non-aureus staphylococci (MRNAS) cause different infections in animals, including mastitis, in livestock and humans. This study aimed to identify and compare the staphylococcal chromosome cassette mec (SCCmec) types of MRSA or MRNAS isolated from several animal species and humans in different countries. Of 1462 S. aureus and non-aureus staphylococci, 68 grew on Chrom MRSA ID^® agar, were phenotypically resistant to cefoxitin and tested positive with the PCR for the mecA gene. These 60 MRSA and 8 MRNAS were isolated in Belgium mainly from cows (livestock-associated (LA) MRS) and humans (community-acquired (CA) MRS) and in Japan from dogs and cats. The SCCmec cassettes were identified by multiplex PCR in 52 MRSA and 7 MRNAS and by whole genome sequencing (WGS) in 8 additional MRSA. The SCCmec types IV and V were the most frequent in Belgian LA-MRS and CA-MRS, while the SCCmec type II was identified in four of the five Japanese MRSA. The remaining isolate was a bovine S. haemolyticus in which no SCCmec was identified. These results confirm the high prevalence of the SCCmec types IV and V in LA-MRS and CA-MRS in Belgium, emphasizing the possible public health hazard of the former, and the absence of SCCmec in some MRNAS.

Epidemiology and Pathogenesis of Staphylococcus Bloodstream Infections in Humans: a Review

Staphylococci are among the most frequent human microbiota components associated with the high level of bloodstream infection (BSI) episodes. In predisposed patients, there is a high risk of transformation of BSI episodes to sepsis. Both bacterial and host factors are crucial for the outcomes of BSI and sepsis. The highest rates of BSI episodes were reported in Africa, where these infections were up to twice as high as the European rates. However, there remains a great need to analyze African data for comprehensive quantification of staphylococcal BSI prevalence. The lowest rates of BSI exist in Australia. Asian, European, and North American data showed similar frequency values. Worldwide analysis indicated that both Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are the most frequent BSI agents. In the second group, the most prevalent species was Staphylococcus epidermidis, although CoNS were not identified at the species level in many studies. The lack of a significant worldwide decrease in BSI episodes indicates a great need to implement standardized diagnostic methods and research etiological factors using advanced genetic methods.

Etomidate Use for Rapid Sequence Intubation Is Not Associated With Nosocomial Infection

INTRODUCTION

Etomidate is commonly used for induction of anesthesia for rapid sequence intubation (RSI). It has little impact on hemodynamic status, making it a widely used agent. Due to the inhibition of cortisol production, etomidate causes adrenal suppression. The purpose of this study is to determine whether there is a correlation with etomidate use and the incidence of secondary infections.

METHODS

This was a retrospective cohort of hospitalized patients who received either etomidate or control (ketamine, propofol, or no agent) for RSI. The primary endpoint was the incidence of secondary infections. Secondary outcomes included number of mechanical ventilator-free days within 28 days, 30-day mortality, length of hospital stay, and length of intensive care unit stay.

RESULTS

A total of 434 patients were reviewed, of which 129 (29.7%) met the study criteria (n = 94 etomidate; n = 35 control). The incidence of secondary infection was numerically higher in the etomidate group compared with the control group, though this was not statistically significant (38.7% vs. 28.6%, p = 0.447). Also, though the secondary outcomes showed no statistically significant difference between the groups, the patients in the control group had a longer hospital stay (14.0 vs. 18.1, p = 0.20) and a longer ICU stay (11.0 vs. 14.1, p = 030). Furthermore, the etomidate group had a non-statistically significant higher incidence of bacteremia (8 vs. 0, p = 0.17).

CONCLUSION

The use of etomidate was not associated with increased incidence of secondary infection. To fully understand the effects of etomidate use and its subsequent adrenal suppression, larger studies are needed.

Should the Vancomycin Minimal Inhibitory Concentration be used as an Infant Critical Care Regular Criteria?

BACKGROUND

Vancomycin is the first-line antibiotic used for the treatment of staphylococcal infections. Because of its narrow therapeutic window and the pharmacokinetics variability, vancomycin trough serum concentration should be monitored. However, due to the increased cases of staphylococcus' commensal species infections and the case of vancomycin resistance, the minimal inhibitory concentration should be considered on antimicrobial therapy.

OBJECTIVE

This article aimed to show the importance of the minimal inhibitory concentration to infants on vancomycin therapy as regular criteria.

MATERIALS AND METHODS

Three infants in the use of vancomycin, hospitalized in the same maternity hospital, and that had at least one blood culture performed during the intensive-care-unit hospitalization were included in the study. Vancomycin serum concentrations were determined by particleenhanced- turbidimetric inhibition-immunoassay. The vancomycin minimal inhibitory concentration data were interpreted by following the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The trough serum concentration range of 10 to 20 mg.L-1 was considered therapeutic.

RESULTS

All three patients had at least one infection by S. epidermidis, being one patient exhibit vancomycin- resistant S. epidermidis infection. All patients had stoppages in the vancomycin treatment, and the minimal inhibitory concentration was performed for only one patient.

CONCLUSION

The data obtained from these patients also showed the need to perform therapeutic monitoring by using minimal inhibitory concentration values, because, although the serum concentrations were within the reference range, they are insufficient to guarantee patient therapeutic success.

Clinical efficacy of teicoplanin in the treatment of bloodstream infection caused by methicillin-resistant coagulase-negative staphylococci

Empirical combination therapy with β-lactams and glycopeptides is recommended for patients with presumed staphylococcal bloodstream infection (BSI). While coagulase-negative staphylococci (CNS) remain susceptible to vancomycin, such isolates have become less susceptible to teicoplanin. The aim of this retrospective study was to evaluate the clinical efficacy of teicoplanin in the treatment of BSI caused by methicillin-resistant CNS according to teicoplanin susceptibility. Inclusion criteria were patients with intravascular-catheter related BSIs caused by methicillin-resistant CNS (positive for two or more specimens); teicoplanin therapy; and at least one of the signs or symptoms caused by BSI. Antimicrobial resistance was defined as minimum inhibitory concentration (MIC) ≥8 μg/mL. The primary efficacy endpoint was clinical success evaluated 2 weeks after the completion of teicoplanin therapy [test of cure (TOC)]. Resistant rate of CNS was 0% for vancomycin and 22.9% for teicoplanin, and geometric mean MICs were 1.31 μg/mL and 3.41 μg/mL, respectively (p < 0.001). The catheter was removed in all patients except one, and high early clinical response at 72 h after starting therapy was obtained irrespective of teicoplanin susceptibility. The clinical success rate at TOC was 60% in patients with BSIs caused by teicoplanin-resistant strains, while 90% in patients with BSIs caused by susceptible strains (p = 0.052). In multivariate analyses, teicoplanin resistance was significant factor for decreased clinical success at TOC (adjusted odds ratio 0.138, 95% confidence interval 0.020-0.961, p = 0.045). Because of the poor clinical efficacy of teicoplanin against teicoplanin-resistant CNS, combination therapy comprising vancomycin and β-lactam antibiotics should be considered in presumed staphylococci BSI.

Prevalence and phylogenetic relationship among methicillin- and vancomycin-resistant Staphylococci isolated from hospital's dairy food, food handlers, and patients

Objective:

The aim of the present work was to investigate the mutual role that may be played by the served dairy food and food handlers in the transmission of methicillin- and vancomycin-resistant Staphylococcus aureus and coagulase-negative Staphylococci to patients who were hospitalized in Qena City, Egypt.

Materials and Methods:

A total of 210 samples including 90 dairy food samples which offered to the patients in the hospital, 60 nasal and hand swabs from food handlers working in the hospital, and 60 nasal and diarrheal swabs from patients suffering from diarrhea were investigated for the presence of coagulase-positive S. aureus and coagulase-negative Staphylococci, then isolates were screened for methicillin and vancomycin resistance phenotypically and genotypically. 16s rRNA gene sequencing was employed to construct the neighbor-joining tree.

Results:

Unlike food samples, both coagulase-positive S. aureus and coagulase-negative Staphylococci occurred in human samples. Methicillin- and vancomycin-resistant coagulase-negative Staphylococci could be detected in 41.7% & 20.8%, 68% & 31.9%, and 81.3% & 55.2% of isolates obtained from dairy food, food handlers, and patients’ samples, respectively. Whereas 81% & 64.3%, and 75.4% & 38.6% of coagulase-positive S. aureus obtained from food handlers and patients’ samples exhibited resistance to methicillin and vancomycin, respectively. Phenotypic resistance was confirmed molecularly through detection of mecA and vanA genes.

Conclusion:

A significant role can be played by food and food handlers in the transmission of methicillin- and vancomycin-resistant Staphylococci to patients, which has been proved in this study through the close phylogenetic relation between S. epidermidis isolated from food, food handlers, and patients’ diarrheal samples.

A short course of antibiotic treatment is safe after catheter withdrawal in catheter-related bloodstream infections due to coagulase-negative staphylococci

CoNS is the main cause of catheter-related bloodstream infections (CRBSI). Current guidelines recommend catheter withdrawal followed by antibiotics for at least 5 days. We aimed to assess the efficacy and safety of a shorter course of antibiotherapy in patients with CoNS CRBSI. All proven cases of CoNS CRBSI at our institution (Jan 12/Dec 17) were retrospectively analysed. Comparison of clinical characteristics and outcomes between patients receiving a short (SC ≤ 3 days) versus long antibiotic course (LC > 3 days) was performed. Cox regression models predicting the risk for complications (including propensity score [PS] for treatment assignment as covariate) were designed to adjust baseline differences among both treatment groups. A total of 79 cases were included. Most patients (75.9%) showed clinical response at day 7 after catheter removal. Complications occurred in 3.8% (three cases of septic thrombophlebitis) with no cases of endocarditis. Microbiological relapse (MR) occurred in 13 patients (16.5%). SC and LC were administered to 25 (31.6%) and 54 (68.4%) patients, respectively, with no significant differences in MR-free survival between SC and LC groups (87.8 vs 86.3%; P = 0.6). In PS-adjusted Cox regression analyses, a tunnelled catheter as the source of CRBSI was the only independent risk factor for MR (hazard ratio, 5.71; 95% confidence interval, 1.6-21) whereas the duration of therapy had no apparent impact. Shortening antibiotic therapy to ≤ 3 days is not associated with a poorer outcome or a greater risk of MR in patients with CoNS CRBI with catheter withdrawal.

Characterization, distribution, antimicrobial resistance and resistance risk factors in staphylococci isolated from cats from 2001 to 2014

Relatively few studies have been published describing the patterns of staphylococcal isolation and antimicrobial resistance over time in cats. The objective of this retrospective study was to determine the frequency, location, characteristics and antimicrobial resistance profiles of staphylococci isolated by the Louisiana Animal Disease Diagnostic Laboratory between the years 2001 and 2014. All feline staphylococcal isolates were classified phenotypically. Isolates corresponding to known or possibly pathogenic species (Staphylococcus intermedius group (SIG) and Staphylococcus aureus (SA)) as well as Staphylococcus epidermidis (SE) and non‐speciated coagulase‐negative staphylococci (CNS) were further evaluated to determine antimicrobial resistance patterns. A total of 519 staphylococci were isolated. The largest percentage of isolates was CNS, representing 39.3% of the total, while SIG, SE, SA and non‐speciated coagulase positive staphylococci (CPS) represented 18.1%, 10.2%, 8.3% and 7.3%, respectively. Methicillin resistance (MR) was identified in 57.1% of SA and 20.5% of SIG. Resistance to 3 or more antimicrobial classes (multidrug resistance; MDR) was demonstrated in 54.5% of SA and 23.9% of SIG. The prevalence of MDR increased over time in both SIG and SA, while the prevalence of MR increased over time in SIG. An increase in mean antimicrobial resistance score over time was seen in SIG. This study demonstrates a high and increasing prevalence of MDR in SIG and SA, as well as increasing prevalence of MR in SIG isolated from cats.