Molecular epidemiology of Staphylococcus aureus strains isolated from inpatients with infected diabetic foot ulcers in an Algerian University Hospital

The Global Prevalence of Methicillin-Resistant Staphylococcus Aureus in Patients with Diabetic Foot Ulcers: A Systematic Review and Meta-Analysis

Objective

Diabetic foot ulcer (DFU) frequently leads to infections, with infected DFUs being a common cause of amputation. Infection by methicillin-resistant Staphylococcus aureus (MRSA) notably increases the necessity for amputation and surgical debridement in affected individuals. Consequently, determining the prevalence and trends of MRSA in patients with DFU is of critical importance. This study aimed to assess the global prevalence and to identify trends in the occurrence of MRSA in tissue or wound swab samples from DFU patients.

Methods

We conducted a comprehensive literature search across PubMed, Embase, Scopus, and Ovid, spanning from the inception of these databases to July 2023, imposing no language restrictions. The inclusion criteria required that the studies report on 30 or more patients with DFU. Additionally, we categorized our analysis based on geographic region, publication date, and the economic status of the patient's domicile. Our primary endpoint was to ascertain the prevalence of MRSA in DFUs. This systematic review has been registered at (https://www.crd.york.ac.uk/prospero/), with the identifier CRD 42023444360.

Results

Our analysis encompassed 40 studies involving 12,924 patients across 20 countries. We found that the overall prevalence of MRSA in DFU was 17% (95% Confidence Interval [CI] 0.14-0.20). Regional prevalence varied significantly: in South America, it was 61% (95% CI 0.46-0.76), in North America 20% (95% CI 0.12-0.27), in Europe 19% (95% CI 0.14-0.25), in Africa 13% (95% CI 0.06-0.20), and in other subgroups 11% (95% CI 0.08-0.15). The prevalence of MRSA in DFUs also differed according to the economic status of the countries: 19% (95% CI 0.15-0.23) in high-income countries, 24% (95% CI 0.1-0.37) in upper-middle-income countries, 11% (95% CI 0.07-0.15) in lower-middle-income countries, and 20% (95% CI 0.13-0.27) in low-income countries. Notably, there has been a decline in MRSA prevalence, from 25% before 2010 to 9% thereafter.

Conclusion

This meta-analysis reveals a decreasing yet still significant global prevalence of MRSA in DFUs. This trend has important implications for antimicrobial resistance and underscores the need for developing targeted programs focusing on infection prevention and exploring alternative therapeutic strategies.

Proportion of toxin and non-toxin virulence factors of Staphylococcus aureus isolates from diabetic foot infection: a systematic review and meta-analysis

BACKGROUND

Staphylococcus aureus isolates are the leading cause of diabetic foot infections (DFIs). Identification of specific virulence factors of S. aureus involved in the pathogenesis of DFIs may help control the infection more effectively. Since the most prevalent virulence factor genes are probably related to the DFI pathogenesis, the aim of this study is to evaluate the proportion of virulence factor genes of S. aureus isolates from DFIs.

MATERIALS AND METHODS

We conducted a systematic search of PubMed, Embase, Web of Science, and Scopus to identify all articles reporting the proportion of different types of virulence factors of S. aureus isolates from DFI samples.

RESULTS

Seventeen studies were eligible, in which 1062 S. aureus isolates were obtained from 1948 patients and 2131 DFI samples. Among the toxin virulence factors, hld 100.0% (95% CI: 97.0, 100.0%), hlg 88.0% (95% CI: 58.0, 100.0%), hla 80.0% (95% CI: 31.0, 100.0%), hlgv 79.0% (95% CI: 35.0, 100.0%) and luk-ED 72.0% (95% CI: 42.0, 95.0%) had the highest proportion respectively. Among the genes associated with biofilm formation, both icaA and icaD had the highest proportion 100.0% (95% CI: 95.6, 100.0%).

CONCLUSION

The results of the present study showed that among the toxin virulence factors, hemolysins (hld, hlg, hla, hlgv) and luk-ED and among the non-toxin virulence factors, icaA and icaD have the greatest proportion in S. aureus isolates from DFIs. These prevalent genes may have the potential to evaluate as virulence factors involved in DFI pathogenesis. Finding these probable virulence factor genes can help control diabetic foot infection more effectively via anti-virulence therapy or preparation of multi-epitope vaccines.

Whole genome sequencing and pan-genome analysis of Staphylococcus/Mammaliicoccus spp. isolated from diabetic foot ulcers and contralateral healthy skin of Algerian patients

BACKGROUND

Diabetic foot infections (DFIs) are the most common complications of diabetic foot ulcers (DFUs), and a significant cause of lower extremity amputation. In this study we used whole genome sequencing to characterize the clonal composition, virulence and resistance genetic determinants of 58 Staphylococcus/Mammaliicoccus spp. isolates from contralateral healthy skin and DFU from 44 hospitalized patients.

RESULTS

S. aureus (n = 32) and S. epidermidis (n = 10) isolates were recovered from both DFUs and healthy skin, whereas, S. haemolyticus (n = 8), M. sciuri (n = 1), S. hominis (n = 1) and S. simulans (n = 3) were recovered exclusively from healthy skin. In contrast, S. caprae (n = 2) and S. saprophyticus (n = 1) were recovered only from DFUs. Among S. aureus isolates, MRSA were present with high prevalence (27/32, 84.4%), 18 of which (66.7%) were from DFUs and 9 (33.3%) from healthy skin. In contrast, the coagulase-negative Staphylococcus (CoNS)/Mammaliicoccus isolates (n = 26), in particular S. epidermidis and S. haemolyticus were more prevalent in healthy skin, (10/26, 38.5%) and (8/26, 30.8%), respectively. MLST, spa and SCCmec typing classified the 32 S. aureus isolates into 6 STs, ST672, ST80, ST241, ST1, ST97, ST291 and 4 unknown STs (STNF); 8 spa types, t044, t037, t3841, t1247, t127, t639, t937 and t9432 and 2 SCCmec types, type IV and type III(A). Among CoNS, the S. epidermidis isolates belonged to ST54, ST35 and ST640. S. haemolyticus belonged to ST3, ST25, ST29, ST1 and ST56. The sole M. sciuri isolate was found to carry an SCCmec type III(A). A wide range of virulence genes and antimicrobial resistance genes were found among our isolates, with varying distribution between species or STs. The pan-genome analysis revealed a highly clonal population of Staphylococcus isolates, particularly among S. aureus isolates. Interestingly, the majority of S. aureus isolates including MRSA, recovered from the healthy skin and DFUs of the same patient belonged to the same clone and exhibited similar virulence/resistance genotype.

CONCLUSIONS

Our study provides clinically relevant information on the population profile, virulence and antibiotic resistance of Staphylococcus/Mammaliicoccus spp. in DFIs, which could serve as a basis for further studies on these as well as other groups of pathogens associated with DFIs.

Staphylococcus aureus Adaptation to the Skin in Health and Persistent/Recurrent Infections

Staphylococcus aureus is a microorganism with an incredible capability to adapt to different niches within the human body. Approximately between 20 and 30% of the population is permanently but asymptomatically colonized with S. aureus in the nose, and another 30% may carry S. aureus intermittently. It has been established that nasal colonization is a risk factor for infection in other body sites, including mild to severe skin and soft tissue infections. The skin has distinct features that make it a hostile niche for many bacteria, therefore acting as a strong barrier against invading microorganisms. Healthy skin is desiccated; it has a low pH at the surface; the upper layer is constantly shed to remove attached bacteria; and several host antimicrobial peptides are produced. However, S. aureus is able to overcome these defenses and colonize this microenvironment. Moreover, this bacterium can very efficiently adapt to the stressors present in the skin under pathological conditions, as it occurs in patients with atopic dermatitis or suffering chronic wounds associated with diabetes. The focus of this manuscript is to revise the current knowledge concerning how S. aureus adapts to such diverse skin conditions causing persistent and recurrent infections.

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

Molecular Characteristics of Staphylococcus aureus Strains Isolated from Nasal Cavity and Wound Infections Among Diabetic Patients

Staphylococcus aureus is the most common pathogen contributing to diabetic foot infections (DFI). Nasal transmission of S. aureus potentially increases the risk of endogenous infection. The aim of this study was to determine the genetic diversity and antibiotic resistance profile of S. aureus isolates in nasal and wound samples from diabetic patients. A cross-sectional study was conducted from July 2018 to September 2019. S. aureus was isolated from the anterior nares and wounds of diabetic patients. All S. aureus isolates were characterized by detection of resistance and virulence genes (mecA, ermA, ermC, hla, hlb, hlg, sea, lukDE, pvl), staphylococcal cassette chromosome mec (SCCmec)-typing and staphylococcal protein A (spa)-typing. A total of 34 S. aureus were isolated from the wounds of 115 diabetic patients with DFI. Twenty-four S. aureus isolates were collected from the anterior nares of patients, and thirteen patients had concurrent S. aureus in nasal and wound specimens. The prevalence of methicillin-resistant S. aureus (MRSA) in nasal specimens was noticeable (41.7%), and the most common spa-type in nasal and wound specimens was t14870. Nearly half of the patients with concurrent S. aureus in wound and nasal specimens had similar isolates from both sites. Our data suggest that detection and screening of S. aureus colonization in the nasal cavity may prevent subsequent endogenous infections, particularly with MRSA strains.

Diabetic foot ulcer: Challenges and future

Diabetic foot ulcers (DFUs) have become one of the important causes of mortality and morbidity in patients with diabetes, and they are also a common cause of hospitalization, which places a heavy burden on patients and society. The prevention and treatment of DFUs requires multidisciplinary management. By controlling various risk factors, such as blood glucose levels, blood pressure, lipid levels and smoking cessation, local management of DFUs should be strengthened, such as debridement, dressing, revascularization, stem cell decompression and oxygen therapy. If necessary, systemic anti-infection treatment should be administered. We reviewed the progress in the clinical practice of treating DFUs in recent years, such as revascularization, wound repair, offloading, stem cell transplantation, and anti-infection treatment. We also summarized and prospectively analyzed some new technologies and measurements used in the treatment of DFUs and noted the future challenges and directions for the development of DFU treatments.

Methicillin-Resistant Staphylococcus aureus from Diabetic Foot Infections in a Tunisian Hospital with the First Detection of MSSA CC398-t571

This study sought to analyze the antimicrobial resistant phenotypes and genotypes as well as the virulence content of S. aureus isolates recovered from patients with diabetic foot infections (DFIs) in a Tunisian hospital. Eighty-three clinical samples of 64 patients were analyzed, and bacterial isolates were identified by MALDI-TOF. The antimicrobial resistance phenotypes were determined by the Kirby-Bauer disk diffusion susceptibility test. Resistance and virulence genes, agr profile, spa and SCCmec types were determined by PCR and sequencing. S. aureus was detected in 14 of the 64 patients (21.9%), and 15 S. aureus isolates were recovered. Six out of the fifteen S. aureus isolates were methicillin-resistant (MRSA, mecA-positive) (40%). The isolates harbored the following resistance genes (number of isolates): blaZ (12), erm(B) (2), erm(A) (1), msrA (2), tet(M) (2), tet(K) (3), tet(L) (1), aac(6')-aph(2″) (2), ant(4″) (1) and fexA (1). The lukS/F-PV and tst genes were detected in three isolates. Twelve different spa-types were identified and assigned to seven clonal complexes with the predominance of agr-type III. Furthermore, the SCCmec types III, IV and V were found among the MRSA isolates. Moreover, one MSSA CC398-t571-agr-III isolate was found; it was susceptible to all antimicrobial agents and lacked luk-S/F-PV, tst, eta and etb genes. This is the first report on the prevalence and molecular characterization of S. aureus from DFIs and also the first detection of the MSSA-CC398-t571 clone in human infections in Tunisia. Our findings indicated a high prevalence S. aureus in DFIs with genetic diversity among the MSSA and MRSA isolates.

Effect of povidone-iodine and propanol-based mecetronium ethyl sulphate on antimicrobial resistance and virulence in Staphylococcus aureus

Background

Reports are available on cross-resistance between antibiotics and biocides. We evaluated the effect of povidone-iodine (PVP-I) and propanol-based mecetronium ethyl sulphate (PBM) on resistance development, antibiotics cross-resistance, and virulence in Staphylococcus aureus.

Methods

The minimum inhibitory concentration (MIC) of PVP-I and PBM were determined against S. aureus ATCC 25923 using the agar-dilution method. Staphylococcus aureus ATCC 25923 was subjected to subinhibitory concentrations of the tested biocides in ten consecutive passages followed by five passages in a biocide-free medium; MIC was determined after each passage and after the fifth passage in the biocide-free medium. The developed resistant mutant was tested for cross-resistance to different antibiotics using Kirby-Bauer disk diffusion method. Antibiotic susceptibility profiles as well as biocides’ MIC were determined for 97 clinical S. aureus isolates. Isolates were categorized into susceptible and resistant to the tested biocides based on MIC distribution pattern. The virulence of the biocide-resistant mutant and the effect of subinhibitory concentrations of biocides on virulence (biofilm formation, hemolysin activity, and expression of virulence-related genes) were tested.

Results

PVP-I and PBM MIC were 5000 μg/mL and 664 μg/mL. No resistance developed to PVP-I but a 128-fold increase in PBM MIC was recorded, by repeated exposure. The developed PBM-resistant mutant acquired resistance to penicillin, cefoxitin, and ciprofloxacin. No clinical isolates were PVP-I-resistant while 48.5% were PBM-resistant. PBM-resistant isolates were more significantly detected among multidrug-resistant isolates. PVP-I subinhibitory concentrations (¼ and ½ of MIC) completely inhibited biofilm formation and significantly reduced hemolysin activity (7% and 0.28%, respectively). However, subinhibitory concentrations of PBM caused moderate reduction in biofilm activity and non-significant reduction in hemolysin activity. The ½ MIC of PVP-I significantly reduced the expression of hla, ebps, eno, fib, icaA, and icaD genes. The virulence of the biocide-resistant mutant was similar to that of parent strain.

Conclusion

PVP-I is a highly recommended antiseptic for use in healthcare settings to control the evolution of high-risk clones. Exposure to PVP-I causes no resistance-development risk in S. aureus, with virulence inhibition by subinhibitory concentrations. Also, special protocols need to be followed during PBM use in hospitals to avoid the selection of resistant strains.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01178-9.

Diabetic foot ulcer disease in African continent: 'From clinical care to implementation' - Review of diabetic foot in last 60 years - 1960 to 2020

The prevalence of diabetes mellitus is increasing globally and the greatest potential increases in diabetes will occur in Africa. Data suggest that these increases is associated with rapid demographic, sociocultural and economic transitions. There will be a parallel increase in the complications of diabetes and among the various complications those related to diabetic foot disease are associated with the highest morbidity and mortality. Diabetic Peripheral neuropathy (DPN) is the most common cause of diabetic foot complications in African countries; however, peripheral arterial disease (PAD) appears to increase, possibly a result of rising urbanization. Search done for the past six decades (1960 to 2020) on all foot complications. Rates of complications of diabetic foot in last six decades varied by country as follow: DPN: 4-90%; PAD: 0-77%; foot ulcers: 4-61%; amputation rates: 3-61% and high mortality rates reaching to 55%, patients who presented late with infection and gangrene. Educational and prevention programmes are required to curb the growing complications of diabetic foot ulcers in Africa among patients and health care workers. Secondly, it is imperative that governments across the African continent recognise the clinical and public health implications of diabetic foot disease in persons with diabetes.

Phenotypic profile and antibiogram of biofilm-producing bacteria isolates from diabetic foot ulcers in Zaria, Nigeria

Background

Diabetic foot ulcers (DFUs) present with high morbidity and reduce patient's quality of life. There is a gross paucity of data on biofilm-producing bacteria in DFU Infection in North-Western Nigeria. The study sought to determine the biofilm-forming ability of bacteria isolates from DFUs and determine their antimicrobial susceptibility pattern in Zaria, North-Western Nigeria.

Materials and Methods

This hospital-based cross-sectional study of patients with DFUs was conducted from June 2018 to February 2020. Consecutive biopsies were aseptically collected. Bacteria were isolated and identified using a Microgen kit. Biofilm forming ability and antibiogram of isolates were determined using microtitre plate and disk diffusion methods, respectively.

Results

Of the 225 participants enrolled, males constituted the majority, 144 (64.0%) with 88 (36.0%) females, the median age of participants was 54 (48-60) years, and the age range was 36-77 years. A total of 172 bacteria were isolated, and 123 (71.5%) were biofilm producers. Staphylococcus aureus (26.7%) was the highest biofilm producer, while Citrobacter freundii and Stenotrophomonas maltophilia were the least biofilm producers, 1 (0.6%) each. A disproportionate resistance pattern was demonstrated among the biofilm and non-biofilm producers against the cephalosporins tested, ceftazidime (68% vs. 18%), ceftriaxone (50% vs. 8.0%) and cefotaxime (21% vs. 0.0%). About 46% and 68% of the biofilm producers were resistant to gentamycin and ciprofloxacin, respectively. While only 2% of the non-biofilm producers were resistant to imipenem, 11% of the biofilm producers were resistant to it.

Conclusion

These findings revealed a high proportion of biofilm-producing bacteria and were more resistant than non-biofilm producers.

Emergence of Methicillin-Resistant Staphylococcus aureus ST239/241 SCCmec-III Mercury in Eastern Algeria

In this paper, we investigate the epidemiology of infections-associated Staphylococcusaureus (S. aureus) from the Medical Intensive Care Unit (MICU) at University Hospital Center of Constantine (UHCC) in Algeria, with a special emphasis on methicillin-resistant strains (MRSA) revealed by cefoxitin disks (30 μg), then confirmed by penicillin-binding protein (PBP2a) agglutination and real-time polymerase chain reaction (RT-PCR) targeting mecA and mecC genes. Staphylococcal Cassette Chromosome mec (SCCmec type), staphylococcal protein A (spa-type), multilocus sequence type (MLST), Panton-Valentine Leucocidin (PVL), and toxic shock syndrome toxin-1 (TSST-1) were further investigated in all isolates, and whole genome sequencing was performed for a selected subset of three hospital-acquired MRSA (HA-MRSA) isolates. A measurement of 80% out of the 50 S. aureus isolates were identified as HA-MRSA harbouring the mecA gene, and 72.5% of them were multidrug resistant (MDR). Twelve STs, four different SCCmec cassettes, fourteen spa types, ten isolates Panton-Valentine Leukocidin (PVL)-positive, and three isolates TSST-1 were identified. Interestingly, there was a high prevalence (n = 29; 72.5%) of a worrisome emerging clone: the HA-MRSA ST239/241 SCCmec-III mercury with PVL negative, resistant to β-lactams, aminoglycosides, quinolones, and tetracyclines. Other clones of HA-MRSA isolates were also identified, including PVL-positive ST80 SCCmec-IV/SCCmec-unknown (22.5%), ST34 SCCmec-V with TSST-1 positive (2.5%), and PVL-negative ST72 SCCmec-II (2.5%). Genome analysis enables us to describe the first detection of both PVL-negative HA-MRSA ST239/241 SCCmec-III mercury carrying ccrC, as well as SCCmec-V cassette, which dramatically changes the epidemiology of S. aureus infections in one of the hospitals in eastern Algeria.

Molecular Characterization of Staphylococcus aureus Isolated from Human and Food Samples in Northern Algeria

Staphylococcus aureus is a commensal resident of the skin and nasal cavities of humans and can cause various infections. Some toxigenic strains can contaminate food matrices and cause foodborne intoxications. The present study aimed to provide relevant information (clonal complex lineages, agr types, virulence and antimicrobial resistance-associated genes) based on DNA microarray analyses as well as the origins and dissemination of several circulating clones of 60 Staphylococcus aureus isolated from food matrices (n = 24), clinical samples (n = 20), and nasal carriers (n = 16) in northern Algeria. Staphylococcus aureus were genotyped into 14 different clonal complexes. Out of 60 S. aureus, 13 and 10 isolates belonged to CC1-MSSA and CC97-MSSA, respectively. The CC 80-MRSA-IV was the predominant S. aureus strain in clinical isolates. The accessory gene regulator allele agr group III was mainly found among clinical isolates (70.4%). Panton–Valentine leukocidin genes lukF/lukS-PV were detected in 13.3% of isolates that all belonged to CC80-MRSA. The lukF/S-hlg, hlgA, and hla genes encoding for hemolysins and leucocidin components were detected in all Staphylococcusaureus isolates. Clinical and food isolates harbored more often the antibiotic resistance genes markers. Seventeen (28.3%) methicillin-resistant Staphylococcus aureus carrying the mecA gene localized on a SCCmec type IV element were identified. The penicillinase operon (blaZ/I/R) was found in 71.7% (43/60) of isolates. Food isolates belonging to CC97-MSSA carried several antibiotic resistance genes (blaZ, ermB, aphA3, sat, tetM, and tetK). The results of this study showed that all clones were found in their typical host, but interestingly, some nasal carriers had isolates assigned to CC705 thought to be absent in humans. The detection of MRSA strains among food isolates should be considered as a potential public health risk. Therefore, controlling the antibiotics prescription for a rational use in human and animal infections is mandatory.

Epidemiology of Methicillin-Resistant Staphylococcus Aureus in Arab Countries of the Middle East and North African (MENA) Region

Available data suggest a high burden of methicillin-resistant staphylococcus aureus (MRSA) in Arab countries of the Middle East and North Africa (MENA). To review the MRSA rates and molecular epidemiology in this region, we used PubMed search engine to identify relative articles published from January 2005 to December 2019. Great heterogeneity in reported rates was expectedly seen. Nasal MRSA colonization ranged from 2%–16% in Gulf Cooperation Council (GCC), 1–9% in the Levant, and 0.2%–9% in North African Arab states. Infective MRSA rates ranged from 9%–38% in GCC, 28%–67% in the Levant, and 28%–57% in North African states. Studies demonstrated a wide clonal diversity in the MENA. The most common molecular types belonged to 5 clonal complexes (CC) known to spread worldwide: CC5, CC8, CC22, CC30, and CC80. The most prevalent strains had genotypes related to the European community-acquired MRSA (CA-MRSA), Brazilian/Hungarian hospital-acquired MRSA (HA-MRSA), UK-EMRSA-15 HA-MRSA, and USA300 CA-MRSA. Finally, significant antimicrobial resistance was seen in the region with variation in patterns depending on location and clonal type. For a more accurate assessment of MRSA epidemiology and burden, the Arab countries need to implement national surveillance systems.

Application and Clinical Effectiveness of Antibiotic-Loaded Bone Cement to Promote Soft Tissue Granulation in the Treatment of Neuropathic Diabetic Foot Ulcers Complicated by Osteomyelitis: A Randomized Controlled Trial

This study explored the clinical effectiveness of antibiotic-loaded bone cement on primary treatment of diabetic foot infection. This is a randomized controlled study, including thirty-six patients with diabetic foot ulcer complicated by osteomyelitis who had undergone treatment between May 2018 and December 2019. Patients were randomly divided into control group (group A) and study group (group B). Patients in the intervention group received antibiotic-loaded bone cement repair as primary treatment, while patients in the control group received conventional vacuum sealing draining treatment. Clinical endpoints were assessed and compared between the two groups, including wound healing time, wound bacterial conversion, NRS pain score, number of wound dressing changes, and average hospitalization time. All patients were followed up for a period of 12 months after discharge. Results show that compared with the control group, patients in the study group had significant difference in the number of patients for baseline pathogens eradication, short NRS pain score, hospital length of stay and cost, wound surface reduction, healing time, low rate of complications, and infection recurrence. Based on the findings, we conclude that antibiotic-loaded bone cement can be used for treatment of wound in patient with diabetic foot infection. It can help to control wound infections, shorten hospital length of stay, reduce medical cost, and relieve both doctors' and patients' burden. The application of antibiotic-loaded bone cement is suitable for diabetic wound with soft tissue infection or osteomyelitis.

Bacterial ecology and antibiotic resistance mechanisms of isolated resistant strains from diabetic foot infections in the north west of Algeria

BACKGROUND

In front of the polymorphic bacterial ecology and antibiotic resistance in diabetic patients with foot infections and good patient care, collaboration between clinicians and microbiologists is needed to improve assessment and management of patients with this pathology.

OBJECTIVE

This study was designed to characterize the bacterial ecology of diabetic foot infection (DFIs) and to determine the different mechanisms of resistance involved.

METHODS

In this study bacterial strains and antibiotic resistance profiles were determined from diabetic foot infections patients (n = 117). The identification of resistance mechanisms, such as penicillinase and/or extended-spectrum β-lactamase production (ESBL), methicillin-resistant Staphylococcus aureus (MRSA) and efflux pump over-expression were performed.

RESULTS

A high prevalence of Gram-negative bacteria (61%) with Escherichia coli, and other Enterobacteriaceae and Pseudomonas aeruginosa being the predominant isolates. Gram positive bacteria mainly represented by Staphylococcus aureus accounted for 39% of the isolates. 93.5% of the Enterobacteriaceae were resistant to, at least, one molecule in the β-lactam family, while the majority of the Staphylococci were resistant to penicillin G and tetracycline (93.3% and 71.7%). The majority of non-fermenting Gram negative bacteria were also resistant to fluoroquinolones. β-lactamase detection tests revealed the presence of extended-spectrum β-lactamase in 43.5% of the Enterobacteriaceae, while methicillin-resistant Staphylococcus aureus represented 18.2% of the isolates. Additionally, 50.9% of non-fermenting Gram negative bacteria were overproducing efflux pumps.

CONCLUSION

All Acinetobacter Baumannii were Multidrug-Resistant (MDR), as the majority of Staphylococci, and Enterobacteriaceae. These results should be taken into account by the clinician in the prescription of probabilistic antibiotic therapy in this context.

Microbiological profile and antimicrobial resistance among diabetic foot infections in Lebanon

Diabetic Foot Infection (DFI) is a challenging complication of diabetes mellitus with a high burden in the Middle East where there is a marked increase in diabetes prevalence and complications. Early detection of DFI and the infectious organisms could result in the early initiation of appropriate antibiotic therapy and improved outcomes. DFI microbiological profiles differ between countries. In our region, Western guidelines are used when initiating treatment for DFI in the absence of local guidance. The purpose of our study was to determine the microbiologic profile and antimicrobial susceptibility of the DFI admissions at a large tertiary referral centre in Beirut and review other reported series in Lebanon and our region. This is a retrospective observational study of patients with DFI admitted to the American University of Beirut Medical Centre from January 2008 to June 2017. The bacteriologic isolation and antimicrobial susceptibility tests were performed according to standard microbiological methods. Between 2008 and 2017, 319 diabetic patients with DFU were admitted to AUBMC, and deep-tissue cultures were taken for 179 patients. From 179 deep tissue cultures, 314 bacterial isolates were obtained. Fifty-four percent of patients had the polymicrobial infection. Aerobic gram-negative rods (GNR) were more prevalent than gram-positive cocci (GPC) (55%, 39%, respectively). The most common isolate was Escherichia coli (15%) followed by Enterococcus (14%) and Pseudomonas aeruginosa (11%). Staphylococcus aureus isolates accounted for 9% with 50% of them being methicillin-resistant (MRSA). Among Enterobacteriaceae, 37% of isolates were fluoroquinolone-resistant, 25% were ESBL producers, and 2% were carbapenem-resistant. Antibiotic resistance was significantly associated with prior usage of antibiotics. Anaerobes were isolated in 1% and Candida species in 5% of isolates. The sensitivity, specificity, PPV, and NPV of swab culture recovery of pathogens compared with deep tissue culture were (76%, 72%, 76%, 72%) and (94%, 81%, 91%, 86%) for gram-positive and gram-negative organisms, respectively. The microbiological profile of DFI in Lebanon is comparable to other countries in the MENA region with big differences compared with the West. Therefore, it is imperative to develop local guidelines for antimicrobial treatment. The high prevalence of GNR in DFI and the high fluoroquinolone resistance should be taken into consideration when choosing empiric antibiotics. Empiric treatment for MRSA or Pseudomonas does not appear necessary except for patients with specific risk factors.

Virulence factors and clonal diversity of Staphylococcus aureus in colonization and wound infection with emphasis on diabetic foot infection

Foot ulcer is a common complication in diabetic subjects and infection of these wounds contributes to increased rates of morbidity and mortality. Diabetic foot infections are caused by a multitude of microbes and Staphylococcus aureus, a major nosocomial and community-associated pathogen, significantly contributes to wound infections as well. Staphylococcus aureus is also the primary pathogen commonly associated with diabetic foot osteomyelitis and can cause chronic and recurrent bone infections. The virulence capability of the pathogen and host immune factors can determine the occurrence and progression of S. aureus infection. Pathogen-related factors include complexity of bacterial structure and functional characteristics that provide metabolic and adhesive properties to overcome host immune response. Even though, virulence markers and toxins of S. aureus are broadly similar in different wound models, certain distinguishing features can be observed in diabetic foot infection. Specific clonal lineages and virulence factors such as TSST-1, leukocidins, enterotoxins, and exfoliatins play a significant role in determining wound outcomes. In this review, we describe the role of specific virulence determinants and clonal lineages of S. aureus that influence wound colonization and infection with special reference to diabetic foot infections.

Microbial spectrum, antibiotic susceptibility profile, and biofilm formation of diabetic foot infections (2014-18): a retrospective multicenter analysis

This study identifies the risk factors, microbiological properties, antimicrobial susceptibility patterns, mortality, and clinical complications associated with organisms causing diabetic foot infections (DFIs) with or without antibiotic treatment using data from a retrospective multicenter surveillance. Specimens collected from different hospitals were cultured and the extended-spectrum β-lactamase (ESBL) excretion was estimated. The antibacterial susceptibility pattern and biofilm formation were completed along with the recommended standard methods. Overall, 792 diabetic foot patients (DFPs) were enrolled and a total of 1803 causative organisms were isolated. Polymicrobial infection was identified in 48.5% of the patients. The isolated Gram-positive pathogens (46.7%) were higher than Gram-negative (38.6%) or anaerobes (7.9%). The predominant pathogens were S. aureus (22.2%), methicillin-resistant S. aureus (7.7%), Enterococcus spp. (12.8%), Pseudomonas aeruginosa (9.4%), E. coli (7.9%), Klebsiella spp. (7.5%), Proteus mirabilis (8.9%), coagulase negative staphylococci (CoNS) (6.6%), anaerobic organisms (5.9%), and fungi (2.3%). Vancomycin and clindamycin exhibited no activity against Gram-positive bacteria. However, meropenem and imipenem displayed high activity against the Gram-negative isolates. Out of the 765 tested strains, 251 showed moderate (15.8%) to high (34%) level biofilm-producing phenotype. DFIs were widespread among the diabetic patients with different microbial etiology and the major organisms were aerobic organisms. Our findings may provide an insight into the development of appropriate therapeutic strategies for the management of DFIs.

Methicillin-Resistant Staphylococcus Aureus (MRSA) in Poultry Species in Algeria: Long-Term Study on Prevalence and Antimicrobial Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is a well-known pathogen with a serious impact on human and veterinary public health. To determine antibiotic resistance of MRSA in poultry, 4248 nasal swabs were collected from 840 poultry farms in 18 different Wilayas (provinces) of Algeria. Swabs were collected between 2011 and 2018 from breeding hens, laying hens, broilers, and turkeys. Identification was carried out by the classical culture methods, and the disc diffusion test was used to determine the antibiotic resistance patterns. S. aureus was isolated from 477 (56.8%) farms, and flock prevalence was 52.8%, 48.8%, 48.4%, and 75.6% in breeding hens, laying hens, broilers, and turkeys, respectively. MRSA was isolated from 252 (30%) farms and flock prevalence was 22%, 33.5%, 27.4%, and 36%, respectively. As expected, all MRSA isolates were resistant to cefoxitin, penicillin G, amoxicillin/clavulanic acid, and oxacillin. High levels of resistance were found for tetracycline (82.5%), erythromycin (70.6%), clindamycin (68.6%), and ciprofloxacin (50%). Almost all isolates were susceptible to vancomycin (100%) and mupirocin and rifampicin (99.2%), followed by chloramphenicol (82.3%), and gentamicin (76%). This moderate proportion of MRSA in poultry poses a considerable risk to public health. The results of this study highlight the need for control programs that encompass primary animal production and the food chain to mitigate contamination and spread of MRSA in the poultry industry of Algeria, and consequently to humans.

Molecular epidemiology and mechanisms of antibiotic resistance in Enterococcus spp., Staphylococcus spp., and Streptococcus spp. in Africa: a systematic review from a One Health perspective

A systematic review of antibiotic-resistant Gram-positive bacteria in Africa from a One Health perspective is lacking. Here, we report result from a search for English-language articles on the resistance mechanisms and clonality of Gram-positive bacteria in Africa between 2007 and 2019 reported in PubMed, Web of Science, ScienceDirect, and African Journals OnLine; 172 studies from 22 different African countries were identified. Resistance genes, such as mecA, erm(B), erm(C), tet(M), tet(K), tet(L), vanB, vanA, vanC, and tet(O), were found to be common. Staphylococcus spp., Enterococcus spp., and Streptococcus spp. were the main species reported by the studies, with clones such as Staphylococcus aureus ST5 (n = 218 isolates), ST8 (n = 127 isolates), ST80 (n = 133 isolates), and ST88 (n = 117 isolates), and mobile genetic elements such as IS16 (n = 28 isolates), IS256 (n = 96), Tn916 (n = 107 isolates), and SCCmec (n = 4437 isolates) identified. SCCmec IV (n = 747 isolates) was predominant, followed by SCCmec III (n = 305 isolates), SCCmec II (n = 163 isolates), SCCmec V (n = 135 isolates), and SCCmec I (n = 79 isolates). Resistance to penicillin (n = 5926 isolates), tetracycline (n = 5300 isolates), erythromycin (n = 5151 isolates), rifampicin (n = 3823 isolates), gentamycin (n = 3494 isolates), sulfamethoxazole/trimethoprim (n = 3089 isolates), and ciprofloxacin (n = 2746 isolates) was common in most reports from 22 countries. Clonal dissemination of resistance across countries and between humans, animals, and the environment was observed. Resistance rates ranged from 1.4% to 100% for 15 of the studies; 10 were One Health-related studies. Strict infection control measures, antimicrobial stewardship, and periodic One Health epidemiological surveillance studies are needed to monitor and contain the threat of increasing antibiotic resistance in Africa.

Methicillin-Resistant Staphylococcus aureus ST80 Clone: A Systematic Review

This review assessed the molecular characterization of the methicillin-resistant Staphylococcus aureus (MRSA)-ST80 clone with an emphasis on its proportion of total MRSA strains isolated, PVL production, spa-typing, antibiotic resistance, and virulence. A systematic review of the literature was conducted on MRSA-ST80 clone published between 1 January 2000 and 31 August 2019. Citations were chosen for a review of the full text if we found evidence that MRSA-ST80 clone was reported in the study. For each isolate, the country of isolation, the sampling period, the source of isolation (the type of infection, nasal swabs, or extra-human), the total number of MRSA strains isolated, number of MRSA-ST80 strains, antibiotic resistance patterns, PVL production, virulence genes, and spa type were recorded. The data from 103 articles were abstracted into an Excel database. Analysis of the data showed that the overall proportion of MRSA-ST80 has been decreasing in many countries in recent years. The majority of MRSA-ST80 were PVL positive with spa-type t044. Only six reports of MRSA-ST80 in extra-human niches were found. This review summarizes the rise of MRSA-ST80 and the evidence that suggests that it could be in decline in many countries.

Bacterial Diversity of Diabetic Foot Ulcers: Current Status and Future Prospectives

Diabetic foot ulcers (DFUs) and diabetic foot infections (DFIs) are associated with reduced patient quality of life, lower-extremity amputation, hospitalization, and high morbidity and mortality. Diverse bacterial communities have been identified in DFUs/DFIs, playing a significant role in infection prognosis. However, due to the high heterogeneity of bacterial communities colonized in DFUs/DFIs, culture-based methods may not isolate all of the bacterial population or unexpected microorganisms. Recently, high sensitivity and specificity of DNA (metagenomics) and RNA (metatranscriptomics) technologies have addressed limitations of culture-based methods and have taken a step beyond bacterial identification. As a consequence, new advances obtained from DNA- and RNA-based techniques for bacterial identification can improve therapeutic approaches. This review evaluated the current state of play in aetiology of DFUs/DFIs on culture and molecular approaches, and discussed the impact of metagenomic and metatranscriptomic methods in bacterial identification approaches.

The prevalence of methicillin-resistant Staphylococcus aureus among diabetic patients: a meta-analysis

AIMS

Diabetic patients have multiple risk factors for colonisation with methicillin-resistant Staphylococcus aureus (MRSA), a nosocomial pathogen associated with significant morbidity and mortality. This meta-analysis was conducted to estimate the prevalence of MRSA among diabetic patients.

METHODS

The MEDLINE, Embase, BIOSIS, and Web of Science databases were searched for studies published up to May 2018 that reported primary data on the prevalence of MRSA in 10 or more diabetic patients. Two authors independently assessed study eligibility and extracted the data. The main outcomes were the pooled prevalence rates of MRSA colonisation and infection among diabetic populations.

RESULTS

Eligible data sets were divided into three groups containing data about the prevalence of MRSA colonisation or in diabetic foot or other infections. From 23 data sets, the prevalence of MRSA colonisation among 11577 diabetics was 9.20% (95% CI, 6.26-12.63%). Comparison of data from 14 studies that examined diabetic and non-diabetic patients found that diabetics had a 4.75% greater colonisation rate (P < 0.0001). From 41 data sets, the prevalence of MRSA in 10994 diabetic foot infection patients was 16.78% (95% CI, 13.21-20.68%). Among 2147 non-foot skin and soft-tissue infections, the MRSA prevalence rate was 18.03% (95% CI, 6.64-33.41).

CONCLUSIONS

The prevalence of MRSA colonisation among diabetic patients is often higher than among non-diabetics; this may make targeted screening attractive. In the UK, many diabetic patients may already be covered by the current screening policies. The prevalence and impact of MRSA among diabetic healthcare workers requires further research. The high prevalence of MRSA among diabetic foot infections may have implications for antimicrobial resistance, and should encourage strategies aimed at infection prevention or alternative therapies.

Bacterial isolation and antibiotic susceptibility from diabetic foot ulcers in Kenya using microbiological tests and comparison with RT-PCR in detection of S. aureus and MRSA

OBJECTIVES

Diabetic foot ulcers (DFUs) often lead to hospital admissions, amputations and deaths; however, there is no up-to-date information on microbial isolates from DFUs and no mention of utilization of molecular techniques in Sub-Saharan Africa. We conducted a cross-sectional study among 83 adult patients at a tertiary hospital in Kenya over 12 months. The study aimed to isolate, identify bacteria, their antibiotic susceptibility patterns in active DFUs, and to compare standard microbiological methods versus a real-time PCR commercial kit in the detection of Staphylococcus aureus DNA and methicillin-resistant S. aureus (MRSA) DNA.

RESULTS

Eighty swabs (94%) were culture-positive; 29% were Gram-positive and 65% were Gram-negative. The main organisms isolated were S. aureus (16%), Escherichia coli (15%), Proteus mirabilis (11%), Klebsiella pneumoniae (7%) and Pseudomonas aeruginosa (7%). The bacterial isolates showed resistance to commonly used antibiotics such as ampicillin, amoxicillin, cefepime, ceftazidime, cefuroxime, clindamycin, erythromycin, piperacillin-tazobactam, tetracycline and trimethoprim-sulphamethoxazole (TMPSMX). Thirty-one percent of the S. aureus isolated and 40% of the Gram-negatives were multi-drug resistant organisms (MDROs). There was a high prevalence of nosocomial bacteria. MRSA were not identified using culture methods but were identified using PCR. PCR was more sensitive but less specific than culture-based methods to identify S. aureus.

In Vivo Biocompatibility of Electrospun Biodegradable Dual Carrier (Antibiotic + Growth Factor) in a Mouse Model-Implications for Rapid Wound Healing

Tissue engineering technologies involving growth factors have produced one of the most advanced generations of diabetic wound healing solutions. Using this approach, a nanocomposite carrier was designed using Poly(d,l-lactide-co-glycolide) (PLGA)/Gelatin polymer solutions for the simultaneous release of recombinant human epidermal growth factor (rhEGF) and gentamicin sulfate at the wound site to hasten the process of diabetic wound healing and inactivation of bacterial growth. The physicochemical characterization of the fabricated scaffolds was carried out using scanning electron microscopy (SEM) and X-ay diffraction (XRD). The scaffolds were analyzed for thermal stability using thermogravimetric analysis and differential scanning calorimetry. The porosity, biodegradability, and swelling behavior of the scaffolds was also evaluated. Encapsulation efficiency, drug loading capacity, and in vitro drug release were also investigated. Further, the bacterial inhibition percentage and detailed in vivo biocompatibility for wound healing efficiency was performed on diabetic C57BL6 mice with dorsal wounds. The scaffolds exhibited excellent wound healing and continuous proliferation of cells for 12 days. These results support the applicability of such systems in rapid healing of diabetic wounds and ulcers.

Can we predict vascular status and culture result based through wound status in diabetic foot infection?

Diabetic foot infection (DFI) should be treated by a multidisciplinary team to prevent amputation and morbid status. As physicians encountering DFI in outpatient clinic, a proper selection of antibiotic treatment and diagnostic approach for a vascular status is essential. We retrospectively investigated the patients with DFI from 2016 to 2017. All patients were examined for vascular status, wound status, and pathologic culture preceding the treatment. No statistical significance was observed between PEDIS grade 1 and 2 and 3 and 4 in culture status and culture results. Association analysis between vascular status and other variables, such as wound score and culture results, has no significant difference. Through these results, the helpful epidemiologic result of microbiology and necessity of examination for peripheral arterial disease were verified.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in the Brazilian primary health care system

OBJECTIVE

To evaluate the molecular epidemiology and to georeference Staphylococcus aureus isolated from wounds and nares of patients seen at Basic Health Units (BHUs) of a Brazilian city.

METHODS

Observational, cross-sectional study conducted from 2010 to 2013. A total of 119 S. aureus strains isolated from the wounds and nares of 88 patients were studied. The isolates were characterised by identifying virulence genes encoding enterotoxins A-E, haemolysins α, β and δ, exfoliatins A, B and D, biofilm production, Panton-Valentine Leukocidin and toxic shock syndrome toxin 1, and by pulsed-field gel electrophoresis (PFGE), multilocus sequence and spa typing.

RESULTS

Eighteen methicillin-resistant Staphylococcus aureus (MRSA) (6 SCCmec type II and 12 SCCmec type IV) and 101 (85%) MSSA were identified. PFGE typing resulted in the formation of eight clusters, with STs 1, 5, 8, 30, 188, 1176 and 1635 and spa type t002 being the predominant types among MSSA. The 18 MRSA belonged to STs 5, 8 and 1176 and spa types t002 and t062.

CONCLUSION

The results demonstrate widespread dissemination of MSSA and MRSA clones carrying haemolysin, biofilm and toxin genes. Kernel density estimation revealed the highest density of S. aureus in the 4, 5 and 8 BHUs.

Classification, microbiology and treatment of diabetic foot infections

Diabetic foot ulcers (DFUs) are a common complication of type-1 and type-2 diabetes. About 10-15% of patients with diabetes develop foot ulcers. A validated foot ulcer classification system that will support the development of treatment strategis is necessary for clinicians managing DFUs. More than 10 classification systems have been described by researchers. Another important aspect of the management of DFUs is the proper identification of causative pathogens that trigger infections. While conventional diagnostic methods, such as swabs, cultures and biopsies are more widely used, novel molecular techniques have been exploring bacterial identification and quantification. Knowledge of the microbial aetiologies in diabetic foot infections, and understanding of antibiotic resistance, is critical for the effective management and treatment of these infected wounds. Initial antibiotic regimens are usually selected empirically. A set of common principles may help avoid selecting either an unnecessarily broad or inappropriately narrow antibiotic treatment regimen. In this review we provide a comprehensive summary and description of classification systems of diabetic foot infections, and a comprehensive discussion of microbiology.

Microbial Diversity of Chronic Wound and Successful Management of Traditional Chinese Medicine

Chronic ulcer, including diabetic ulcer, varicose ulcer, and pressure ulcer, negatively affects patients' quality of life. As microbiology plays an important role in the mechanism of pathology for chronic wound healing, this study concentrates on microecology environment of the wound and how Traditional Chinese Medicine (TCM) regulates wound bacteria. Method. The study took wound samples from 35 patients and analyzed bacteria variation before and after TCM treatment by 16s rRNA sequencing. All samples were evaluated from aspects of α-diversity, β-diversity, and Simpson's Diversity index. Result. After total DNA extraction, PCR, and 16S rRNA sequencing of wound bacteria from 35 individuals, it was discovered that younger patients with shorter course of disease have a higher microbial diversity and were easier to recover from ulcers. Additionally, gender also played a vital role in wound healing, and a significant microbial diversity existed between male and female patients. Conclusion. Patients with chronic ulcers achieved a positive effect after TCM treatment (skin-producing ointment). Mechanistically, TCM helped promote wound healing by regulating the wound microbiota.

Polymicrobial interactions influence the agr copy number in Staphylococcus aureus isolates from diabetic foot ulcers

Diabetic foot ulcers are a major complication of diabetes and are often colonised by complex bacterial communities, where Staphylococcus aureus is frequently co-present with Pseudomonas aeruginosa. These bacteria interact through quorum sensing, encoded in S. aureus by the accessory gene regulator (agr). Typing and copy number of S. aureus agr were assessed here to give insights on strain variability and possible interspecies influence. As agr is classified in four genetic groups, agr-I, agr-II, agr-III and agr-IV, the agr type of 23 S. aureus diabetic foot ulcers isolates was evaluated by PCR and gene copy number determined by qPCR, including in S. aureus present in polymicrobial infections. agr-I and agr-II were found to be present in 52 and 39% of the isolates, respectively. In two isolates, no agr type was identified, and types III and IV were not detected. Interestingly, agr-II copy number was higher in dual suspensions than in S. aureus single suspension. We conclude that agr type I was the most frequent in clinical centers in Lisbon, and variations in agr-I and agr-II copy numbers were strain specific. Variations in agr copy number in dual suspensions suggests that P. aeruginosa may influence S. aureus agr-II gene regulation, confirming an interaction between these two bacteria. This is a first approach to characterise agr variation in S. aureus from diabetic foot ulcers in vitro.

Virulence Factor Genes in Staphylococcus aureus Isolated From Diabetic Foot Soft Tissue and Bone Infections

The aim of this study is to describe the presence of genes encoding for 4 virulence factors (pvl, eta, etb, and tsst), as well as the mecA gene conferring resistance to beta-lactam antibiotics, in patients with diabetes and a staphylococcal foot infection. We have also analyzed whether isolates of Staphylococcus aureus from bone infections have a different profile for these genes compared with those from exclusively soft tissue infections. In this cross-sectional study of a prospectively recruited series of patients admitted to the Diabetic Foot Unit, San Juan de Dios Hospital, San José, Costa Rica with a moderate or severe diabetic foot infection (DFI), we collected samples from infected soft tissue and from bone during debridement. During the study period (June 1, 2014 to May 31, 2016), we treated 379 patients for a DFI. S aureus was isolated from 101 wound samples, of which 43 were polymicrobial infections; we only included the 58 infections that were monomicrobial S aureus for this study. Infections were exclusively soft tissue in 17 patients (29.3%) while 41 (70.7%) had bone involvement (osteomyelitis). The mecA gene was detected in 35 cases (60.3%), pvl gene in 4 cases (6.9%), and tsst gene in 3 (5.2%). We did not detect etA and etB in any of the cases. There were no differences in the profile of S aureus genes encoding for virulence factors (pvl, etA, etB, and tsst) recovered from DFIs between those with just soft tissue compared to those with osteomyelitis. However, we found a significantly higher prevalence of pvl+ strains of S aureus associated with soft tissue compared with bone infections. Furthermore, we observed a significantly longer time to healing among patients infected with mecA+ (methicillin-resistant) S aureus (MRSA).

Emergence of Nasal Carriage of ST80 and ST152 PVL+ Staphylococcus aureus Isolates from Livestock in Algeria

The spread of toxinogenic Staphylococcus aureus is a public health problem in Africa. The objectives of the study were to investigate the rate of S. aureus nasal carriage and molecular characteristics of these strains in livestock and humans in three Algerian provinces. Nasal samples were collected from camels, horses, cattle, sheep and monkeys, as well as humans in contact with them. S. aureus isolates were genotyped using DNA microarray. The rate of S. aureus nasal carriage varied between species: camels (53%), humans and monkeys (50%), sheep (44.2%), horses (15.2%) and cattle (15%). Nine methicillin-resistant S. aureus (MRSA) isolates (7.6%) were identified, isolated from camels and sheep. The S. aureus isolates belonged to 15 different clonal complexes. Among them, PVL+ (Panton–Valentine Leukocidin) isolates belonging to ST80-MRSA-IV and ST152-MSSA were identified in camels (n = 3, 13%) and sheep (n = 4, 21.1%). A high prevalence of toxinogenic animal strains was noted containing TSST-1- (22.2%), EDINB- (29.6%) and EtD- (11.1%) encoding genes. This study showed the dispersal of the highly human pathogenic clones ST152-MSSA and ST-80-MRSA in animals. It suggests the ability of some clones to cross the species barrier and jump between humans and several animal species.

Severity of drug resistance and co-existence of Enterococcus faecalis in diabetic foot ulcer infections

The genes encoding aminoglycoside resistance in Enterococcus faecalis may promote collateral aminoglycoside resistance in polymicrobial wounds. We studied a total of 100 diabetic foot ulcer samples for infection and found 60 samples to be polymicrobial, 5 to be monomicrobial, and 35 samples to be culture negative. A total of 65 E. faecalis isolates were screened for six genes coding for aminoglycoside resistance, antibiotic resistance patterns, and biofilm production. Infectious Diseases Society of America/International Working Group on the Diabetic Foot system was used to classify the wound ulcers. Majority of the subjects with culture-positive wound were recommended conservative management, while 14 subjects underwent amputation. Enterococcal isolates showed higher resistance for erythromycin, tetracycline, and ciprofloxacin. Isolates from grade 3 ulcer showed higher frequency of aac(6')-Ie-aph(2″)-Ia, while all the isolates were negative for aph(2″)-Ib, aph(2″)-Ic, and aph(2″)-Id. The isolates from grade 3 ulcers showed higher resistance to aminoglycosides as well as teicoplanin and chloramphenicol. All the 39 biofilm producers were obtained from polymicrobial wound and showed higher resistance when compared to biofilm non-producers. Higher frequency of isolates carrying aac(6')-Ie-aph(2″)-Ia in polymicrobial community showing resistance to key antibiotics suggests widespread distribution of aminoglycoside-resistant E. faecalis and their role in worsening diabetic foot ulcers.

The global diabetes epidemic: what does it mean for infectious diseases in tropical countries?

Tropical countries are experiencing a substantial rise in type 2 diabetes, which is often undiagnosed or poorly controlled. Since diabetes is a risk factor for many infectious diseases, this increase probably adds to the large infectious disease burden in tropical countries. We reviewed the literature to investigate the interface between diabetes and infections in tropical countries, including the WHO-defined neglected tropical diseases. Although solid data are sparse, patients with diabetes living in tropical countries most likely face increased risks of common and health-care-associated infections, as well as infected foot ulcers, which often lead to amputation. There is strong evidence that diabetes increases the severity of some endemic infections such as tuberculosis, melioidosis, and dengue virus infection. Some HIV and antiparasitic drugs might induce diabetes, whereas helminth infections appear to afford some protection against future diabetes. But there are no or very scarce data for most tropical infections and for possible biological mechanisms underlying associations with diabetes. The rise in diabetes and other non-communicable diseases puts a heavy toll on health systems in tropical countries. On the other hand, complications common to both diabetes and some tropical infections might provide an opportunity for shared services-for example, for eye health (trachoma and onchocerciasis), ulcer care (leprosy), or renal support (schistosomiasis). More research about the interaction of diabetes and infections in tropical countries is needed, and the infectious disease burden in these countries is another reason to step up global efforts to improve prevention and care for diabetes.

Monoclonal antibodies protect from Staphylococcal Enterotoxin K (SEK) induced toxic shock and sepsis by USA300 Staphylococcus aureus

Staphylococcus aureus is a leading infectious cause of life-threatening disease in humans, yet there is currently no vaccine to combat this bacterium. The pathogenesis of S. aureus is mediated by a diverse array of protein toxins including a large family of secreted pyrogenic superantigens. Neutralization of superantigens, including SEB and TSST-1, has proven to be protective in several animal models of toxic shock and sepsis. We demonstrate, for the first time, that a far more prevalent staphylococcal superantigen, SEK, can also induce lethal shock in mice. Additionally, we describe monoclonal antibodies (mAbs) that inhibit SEK-induced mitogenicity as well as protect against SEK-induced lethality, and enhance survival from S. aureus septicemia in murine models. MAb-4G3 (IgG2b), mAb-5G2 (IgG1), and mAb-9H2 (IgG1), all inhibit SEK-induced proliferation and cytokine production of human immune cells. We then demonstrate that passive immunization with a combination of mAb-4G3 and mAb-5G4, 2 mAbs that do not compete for epitope(s) on SEK, significantly enhance survival in a murine model of SEK-induced toxic shock (p = 0.006). In the setting of sepsis, passive immunization with this combination of mAbs also significantly enhances survival in mice after challenge with CA-MRSA strain USA300 (p = 0.03). Furthermore, septic mice that received mAb treatment in conjunction with vancomycin exhibit less morbidity than mice treated with vancomycin alone. Taken together, these findings suggest that the contribution of SEK to S. aureus pathogenesis may be greater than previously appreciated, and that adjunctive therapy with passive immunotherapy against SEs may be beneficial.

Staphylococcus aureus Toxins and Diabetic Foot Ulcers: Role in Pathogenesis and Interest in Diagnosis

Infection of foot ulcers is a common, often severe and costly complication in diabetes. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. The numerous virulence factors and toxins produced by S. aureus during an infection are well characterized. However, some particular features could be observed in DFI. The aim of this review is to describe the role of S. aureus in DFI and the implication of its toxins in the establishment of the infection. Studies on this issue have helped to distinguish two S. aureus populations in DFI: toxinogenic S. aureus strains (harboring exfoliatin-, EDIN-, PVL- or TSST-encoding genes) and non-toxinogenic strains. Toxinogenic strains are often present in infections with a more severe grade and systemic impact, whereas non-toxinogenic strains seem to remain localized in deep structures and bone involving diabetic foot osteomyelitis. Testing the virulence profile of bacteria seems to be a promising way to predict the behavior of S. aureus in the chronic wounds.

Causative pathogens and antibiotic resistance in diabetic foot infections: A prospective multi-center study

AIM

Clinical practice guidelines for the management of diabetic foot infections developed by the Infectious Diseases Society of America (IDSA) are commonly used worldwide. The issue of whether or not these guidelines need to be adjusted for local circumstances, however, has seldom been assessed in large prospective trials.

METHODS

The Turk-DAY trial was a prospective, multi-center study in which infectious disease specialists from centers across Turkey were invited to participate (NCT02026830).

RESULTS

A total of 35 centers throughout Turkey enrolled patients in the trial. Overall, investigators collected a total of 522 specimens from infected diabetic foot wounds for culture from 447 individual patients. Among all isolates, 36.4% were gram-positive organisms, with Staphylococcus aureus the most common among these (11.4%). Gram-negative organisms constituted 60.2% of all the isolates, and the most commonly isolated gram-negative was Escherichia coli (15%). The sensitivity rates of the isolated species were remarkably low for several antimicrobials used in the mild infection group.

CONCLUSIONS

Based on our findings, several of the antimicrobials frequently used for empirical treatment, including some also recommended in the IDSA guidelines, would not be optimal for treating diabetic foot infections in Turkey. Although the IDSA guideline recommendations may be helpful to guide empiric antimicrobial therapy of DFIs, they should be adjusted to local conditions.

Susceptibility patterns of Staphylococcus aureus biofilms in diabetic foot infections

BACKGROUND

Foot infections are a major cause of morbidity in people with diabetes and the most common cause of diabetes-related hospitalization and lower extremity amputation. Staphylococcus aureus is by far the most frequent species isolated from these infections. In particular, methicillin-resistant S. aureus (MRSA) has emerged as a major clinical and epidemiological problem in hospitals. MRSA strains have the ability to be resistant to most β-lactam antibiotics, but also to a wide range of other antimicrobials, making infections difficult to manage and very costly to treat. To date, there are two fifth-generation cephalosporins generally efficacious against MRSA, ceftaroline and ceftobripole, sharing a similar spectrum. Biofilm formation is one of the most important virulence traits of S. aureus. Biofilm growth plays an important role during infection by providing defence against several antagonistic mechanisms. In this study, we analysed the antimicrobial susceptibility patterns of biofilm-producing S. aureus strains isolated from diabetic foot infections. The antibiotic minimum inhibitory concentration (MIC) was determined for ten antimicrobial compounds, along with the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC), followed by PCR identification of genetic determinants of biofilm production and antimicrobial resistance.

RESULTS

Results demonstrate that very high concentrations of the most used antibiotics in treating diabetic foot infections (DFI) are required to inhibit S. aureus biofilms in vitro, which may explain why monotherapy with these agents frequently fails to eradicate biofilm infections. In fact, biofilms were resistant to antibiotics at concentrations 10-1000 times greater than the ones required to kill free-living or planktonic cells. The only antibiotics able to inhibit biofilm eradication on 50 % of isolates were ceftaroline and gentamicin.

CONCLUSIONS

The results suggest that the antibiotic susceptibility patterns cannot be applied to biofilm established infections. Selection of antimicrobial therapy is a critical step in DFI and should aim at overcoming biofilm disease in order to optimize the outcomes of this complex pathology.

Isolation and Genetic Analysis of Multidrug Resistant Bacteria from Diabetic Foot Ulcers

Severe diabetic foot ulcers (DFUs) patients visiting Sir Sunderlal Hospital, Banaras Hindu University, Varanasi, were selected for this study. Bacteria were isolated from swab and deep tissue of 42 patients, for examining their prevalence and antibiotic sensitivity. DFUs of majority of the patients were found infected with Enterococcus spp. (47.61%), Escherichia coli (35.71%), Staphylococcus spp. (33.33%), Alcaligenes spp. (30.95%), Pseudomonas spp. (30.95%), and Stenotrophomonas spp. (30.95%). Antibiotic susceptibility assay of 142 bacteria with 16 antibiotics belonging to eight classes showed the presence of 38 (26.76%) isolates with multidrug resistance (MDR) phenotypes. MDR character appeared to be governed by integrons as class 1 integrons were detected in 26 (68.42%) isolates. Altogether six different arrays of genes (aadA1, aadB, aadAV, dhfrV, dhfrXII, and dhfrXVII) were found within class 1 integron. Gene cassette dhfrAXVII-aadAV (1.6 kb) was present in 12 (3 Gram positive and 9 Gram negative) isolates and was conserved across all the isolates as evident from RFLP analysis. In addition to the presence of class 1 integron, six β-lactamase resistance encoding genes namely bla TEM, bla SHV, bla OXA, bla CTX-M-gp1, bla CTX-M-gp2, and bla CTX-M-gp9 and two methicillin resistance genes namely mecA and femA and vancomycin resistance encoding genes (vanA and vanB) were identified in different isolates. Majority of the MDR isolates were positive for bla TEM (89.47%), bla OXA (52.63%), and bla CTX-M-gp1 (34.21%). To our knowledge, this is the first report of molecular characterization of antibiotic resistance in bacteria isolated from DFUs from North India. In conclusion, findings of this study suggest that class-1 integrons and β-lactamase genes contributed to the MDR in above bacteria.

The role of anaerobes in diabetic foot infections

Diabetic foot infections (DFI) are a common cause of morbidity and, on occasion, even mortality. Infection can be either mono- or polymicrobial, with a wide variety of potential pathogens. Anaerobes may be involved, particularly in wounds that are deeper or more chronic, and are more frequently identified when using modern molecular techniques, such as 16s PCR and pyrosequencing. It remains unclear whether the presence of anaerobes in DFI leads to more severe manifestations, or if these organisms are largely colonizers associated with the presence of greater degrees of tissue ischemia and necrosis. Commonly used empiric antibiotic therapy for diabetic foot infections is generally broad-spectrum and usually has activity against the most frequently identified anaerobes, such as Peptostreptococcus and Bacteroides species. Adequate surgical debridement and, when needed, foot revascularization may be at least as important as the choice of antibiotic to achieve a successful treatment outcome.

Do Diabetic Foot Infections With Methicillin-Resistant Staphylococcus aureus Differ From Those With Other Pathogens?

There is controversy as to whether or not diabetic foot infections (DFIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with worse outcomes than DFIs caused by other pathogens. To address this issue we performed a nonsystematic literature search of published articles in English language journals seeking studies reporting on the outcomes of DFIs related to their microbiology. We retrieved 48 articles published from 1999 to 2013 that described a total of 7771 cases of DFI. The overall proportion of DFIs with an isolate of S aureus was about 30%; just over one third of these (11% of all cases) were MRSA strains. Among the DFI cases caused by MRSA 1543 were episodes of soft tissue infections and 113 of osteomyelitis, while non-MRSA organisms caused 5761 soft tissue infections and 354 cases of osteomyelitis. Only 5 of the included articles attempted a comparison between DFI caused by MRSA and those caused by other pathogens, with no clear differences noted. The median total duration of antibiotic therapy for DFI caused by MRSA was 26 days, of which a median of 10 days was given intravenously. Only a few articles reported the proportion of patients with a recurrence, but they often did not differentiate between MRSA and non-MRSA cases. Four publications reported a worse functional or microbiological outcome in MRSA, compared to non-MRSA, cases, but the findings were variable and differences did not seem to be significant. Many trials failed to adjust for case-mix or to definitively demonstrate a relationship between microbiology and outcomes. Few of the articles specifically commented on whether the MRSA isolates were health care- or community-acquired strains. Notwithstanding the substantial limitations of the available literature, there does not appear to be a need for any special treatment for DFI caused by MRSA. The current guidelines for treating according to established international recommendations seem appropriate.

Detection and measurement of staphylococcal enterotoxin-like K (SEl-K) secretion by Staphylococcus aureus clinical isolates

Staphylococcal enterotoxin-like K (SEl-K) is a potent mitogen that elicits T-cell proliferation and cytokine production at very low concentrations. However, unlike the classical enterotoxins SEB and toxic shock syndrome toxin 1 (TSST-1), the gene for SEl-K is commonly present in more than half of all Staphylococcus aureus clinical isolates and is present in almost all USA300 community-acquired methicillin-resistant S. aureus (CA-MRSA) isolates. Sequencing of the sel-k gene in over 20 clinical isolates and comparative analysis with all 14 published sel-k sequences indicate that there are at least 6 variants of the sel-k gene, including one that is conserved among all examined USA300 strains. Additionally, we have developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) that specifically detects and measures SEl-K protein in culture supernatants and biological fluids. Quantification of in vitro SEl-K secretion by various S. aureus isolates using this novel capture ELISA revealed detectable amounts of SEl-K secretion by all isolates, with the highest secretion levels being exhibited by MRSA strains that coexpress SEB. In vivo secretion was measured in a murine thigh abscess model, where similar levels of SEl-K accumulation were noted regardless of whether the infecting strain exhibited high or low secretion of SEl-K in vitro. We conclude that SEl-K is commonly expressed in the setting of staphylococcal infection, in significant amounts. SEl-K should be further explored as a target for passive immunotherapy against complicated S. aureus infection.

Diabetic foot infections: state-of-the-art

Foot infections are frequent and potentially devastating complications of diabetes. Unchecked, infection can progress contiguously to involve the deeper soft tissues and ultimately the bone. Foot ulcers in people with diabetes are most often the consequence of one or more of the following: peripheral sensory neuropathy, motor neuropathy and gait disorders, peripheral arterial insufficiency or immunological impairments. Infection develops in over half of foot ulcers and is the factor that most often leads to lower extremity amputation. These amputations are associated with substantial morbidity, reduced quality of life and major financial costs. Most infections can be successfully treated with optimal wound care, antibiotic therapy and surgical procedures. Employing evidence-based guidelines, multidisciplinary teams and institution-specific clinical pathways provides the best approach to guide clinicians through this multifaceted problem. All clinicians regularly seeing people with diabetes should have an understanding of how to prevent, diagnose and treat foot infections, which requires familiarity with the pathophysiology of the problem and the literature supporting currently recommended care.

Detection and genetic characterization of PVL-positive ST8-MRSA-IVa and exfoliative toxin D-positive European CA-MRSA-Like ST1931 (CC80) MRSA-IVa strains in Bangladesh

Severe skin lesions caused by Staphylococcus aureus infection are associated with production from bacterial cells of Panton-Valentine leukocidin (PVL), a typical virulence factor of community-acquired methicillin-resistant S. aureus (CA-MRSA), as well as other toxins represented by exfoliative toxins. Through a retrospective study of 26 S. aureus strains isolated from skin lesions of diabetic patients admitted to a hospital in Bangladesh, 2 PVL-gene-positive MRSA-IVa strains and 8 PVL-negative, exfoliative toxin D (ETD) gene (etd)-positive MRSA-IVa strains were isolated. A PVL-positive MRSA-IVa strain had a type I arginine catabolic mobile element (ACME), belonged to ST8/agr-type I/spa-type t121 (a variant of t008), and harbored blaZ, tet(K), msrA, and aph(3')-IIIa, which are mostly typical characteristics found in USA300, a predominant CA-MRSA clone in the United States. Another PVL-positive MRSA strain, belonging to ST1929 (CC88)/agr-type III/spa-type t3341, was negative for ACME, but possessed blaZ and tet(K). The etd-positive MRSA-IVa strains possessed the epidermal cell differentiation inhibitor B (EDIN-B)-encoding gene (edinB) and belonged to ST1931 (CC80)/agr-type III/spa-type t11023 (a variant of t044), which was genetic trait similar to that of the European CA-MRSA ST80 clone. However, unlike the European ST80 strains, the etd-positive MRSA strains detected in the present study harbored seb, sek, and seq, while they were negative for tet(K), aph(3')-IIIa, and fusB, showing susceptibility to fusidic acid. These findings suggested that etd-positive ST1931 MRSA strains belong to the same lineage as the European ST80 MRSA clone, evolving from a common ancestral clone via acquisition of a different pathogenicity island. This is the first report of a USA300-like MRSA-IV strain, PVL-positive ST1929 (CC88) MRSA-IV, and European ST80 CA-MRSA-like etd-positive ST1931 (CC80) MRSA-IV strains isolated in Bangladesh.

Emergence of the European ST80 clone of community-associated methicillin-resistant Staphylococcus aureus as a cause of healthcare-associated infections in Eastern Algeria

AIMS

The authors had for aim to assess whether an in-hospital spread of the European community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone was on-going in Annaba, Eastern Algeria.

MATERIAL AND METHODS

We carried out a molecular epidemiological study of S. aureus strains causing infections in 4 hospitals located in Annaba, between February and October 2010.

RESULTS

Our study revealed a very low healthcare-associated MRSA (HCA-MRSA) infection incidence rate of 0.34 per 1000 patient-days. However, the rates of HCA-MRSA strains (85/119) and CA-MRSA (7/29) among S. aureus strains are much higher than those found in France. The European CA-MRSA clone (clonal complex 80, Staphylococcal Cassette Chromosome mec IVc, spa type t044, lukS/F-PV-positive) accounted for 14.1% of all healthcare-associated (HCA) MRSA infections.

CONCLUSION

This study confirmed the emerging role of CA-MRSA as HCA pathogens in North-African Africa.