Mupirocin-Resistant Staphylococcus aureus in Iran: A Biofilm Production and Genetic Characteristics

The spread of mupirocin-resistant Staphylococcus aureus strains in hospitals and communities is a universal challenge. Limited data is available on the genetic features of high-level mupirocin resistant- (HLMUPR-) S. aureus isolates in Tehran. In the present research, we investigated 48 high-level mupirocin resistance S. aureus by antimicrobial activity, virulence analysis, biofilm formation, multilocus sequence typing (MLST), and staphylocoagulase (SC) typing. All the HLMUPR strains were positive for mupA gene. The frequency of multidrug resistance was 97.9%. Twenty-one (43.8%) were toxinogenic with 14 producing pvl (29.2%), 5 tst (10.4%), and two eta (4.2%). Among the HLMUPR isolates, biofilm production was detected in 45 (89.6%) isolates with complete dominance clfB, clfA genes, and a noticeably high frequency fnbA (95.8%), followed by fnbB (93.8%), eno and icaD (each 83.3%), sdrC (81.3%), ebps (79.2%), icaA (75%), sdrD (66.7%), fib (60.4%), sdrE (50%), cna (41.7%), and bap (4.2%). Coagulase typing distinguished isolates into four genotypic patterns including III (50%), II (27.1%), and type IVa (22.9%). A total of three clonal complexes (CCs) and 4 sequence types (STs) including CC/ST22 as the most prevalent (52.1%), CC8/ST239 (20.8%), CC/ST8 (16.7%), and CC/ST5 (10.4%) were identified in current work. According to our analysis, nonbiofilm producer isolates belonged to CC8/ST239 (6.3%) and CC/ST8 (4.2%). Fusidic acid-resistant isolates belonged to CC/ST45 ( n = 3 ) and CC8/ST239 ( n = 1 ). Observations highlighted the circulation of the CC/ST22 HLMUPR S. aureus strains with strong biofilm-production ability in our hospitals, indicating the possibility of transmission of this type between community and hospital.

Mupirocin Resistance of Staphylococcus aureus in Clinical Isolates of National Hospital and in the Nasal Carriage of Healthy Undergraduates in Colombo, Sri Lanka

Introduction and Objectives : Mupirocin resistance in Staphylococcus aureus is increasingly reported in many parts of the world. This study was conducted with the objective of describing high-level and low-level mupirocin resistance of S. aureus in clinical isolates and nasal carriage. Materials and Methods : A descriptive study was conducted including 45 nasal isolates of S. aureus collected from healthy university students in Colombo and 249 clinical isolates of S. aureus from the patient specimens in National Hospital of Sri Lanka. All of the confirmed S. aureus strains were tested for methicillin resistance using cefoxitin disc (30μg). S. aureus isolates were considered methicillin-resistant if the diameter of zone of inhibition was 21mm or less (CLSI, 2017). The S. aureus isolates were then tested for mupirocin resistance. Disk diffusion method was utilized with 5μg and 200μg mupirocin discs to determine low-level and high-level resistances respectively. The criterion employed for interpretation of mupirocin resistance was a combination of the widely accepted criterion described by Finlay, Miller, and Poupard (1997) for low-level mupirocin resistance and CLSI (2017) criterion for high-level mupirocin resistance. If both inhibition zone diameters for 5μg disk and 200μg were ≥14mm, the isolate was considered mupirocin sensitive. If 5μg disc displays <14mm and 200 μg disk displayed ≥14mm inhibition zone diameter, the isolate was considered to be mupirocin low level resistant. If there is no inhibition zone in 200μg disk, the isolate was considered as mupirocin high level resistant. Results : From the 45 nasal carriage isolates, 33 (73%) were Methicillin sensitive Staphylococcus aureus (MSSA) and 12 (27%) were Methicillin Resistant Staphylococcus aureus (MRSA). Among the clinical isolates, majority (n=158, 63%) were MRSA while only 91 (37%) MSSA. An overall mupirocin resistance rate of 4.4% among S. aureus was observed. Low-level mupirocin resistance was observed in 3.7% Staphylococcus aureus isolates and high-level mupirocin resistance was observed in 0.7% isolates. Mupirocin low-level and high-level resistance in MRSA isolates were 5.3% and 0.6% respectively. MSSA isolates demonstrated 1.6% (n=2) and 0.8% (n=1) mupirocin low-level and high-level resistances respectively. None of the nasal isolates were resistant to mupirocin while 6% (n=15) mupirocin low-level resistance and 0.8% (n=2) mupirocin high-level resistance was observed in clinical isolates. Conclusion : This initial survey of mupirocin resistance among S. aureus in a country with fairly high usage of mupirocin emphasizes that although the overall mupirocin resistance is relatively low in this population, regular surveillance of mupirocin resistance remains a necessity.

Mupirocin Resistance in Staphylococcus aureus Isolated from Nasal Swabs of ICU and OT Staff- A Study from A Tertiary Care Hospital

Staphylococcus aureus is one of the common causes of Healthcare-associated infection. Staphylococcus colonizes the anterior nares of the nose and tends to disseminate and secondarily colonize several other body sites including the skin and the gut. Colonized hospital personnel may be an important factor in dissemination. Staphylococcus aureus to patients and vice-versa. Mupirocin is an excellent topical anti-staphylococcal antimicrobial agent used for eradicating nasal carriage. Resistance to Mupirocin is a threat for future use of this drug in eliminating nasal carriage of Staphylococcus aureus. Thus, this study was conducted to determine the rate of Mupirocin resistance among Staphylococcus aureus isolated from nasal swabs of Health care workers (HCWs ) of Operation Theatres (OTs) and Intensive Care Units (ICUs). A single nasal swab was collected from both the anterior nares of participating health care workers of ICU and OT once at the end of their shift. Antibiotic susceptibility testing of Staphylococcus aureus to various antibiotics was done by Kirby-Bauer disk diffusion method using CLSI guidelines. High and low-level Mupirocin resistance was determined. Among 282 nasal swabs collected, Staphylococcus aureus was isolated in 62 samples. Of Staphylococcus aureus 19 came out to be Methicillin-resistant (MRSA) and the remaining 43 Methicillin sensitive (MSSA). Mupirocin resistance was seen in 3 MRSA strains and 1 MSSA strain. Thus, overall 4/62 (6.5%) strains were MupR strains. Mupirocin is the most effective antibiotic used against colonization of Staphylococcus aureus in anterior nares. Resistance to this antibiotic is thus an alarm as well as a matter of great concern. Necessary steps, policies and guidelines need to be framed to stop the spread of this resistance.

Reduced Susceptibility to Chlorhexidine among Staphylococcus aureus Isolates in Israel: Phenotypic and Genotypic Tolerance

Antiseptic use for body decolonization is the main activity applied to prevent healthcare-associated infections, including those caused by S. aureus. Consequentially, tolerance to several antiseptics such as chlorhexidine gluconate (CHG) has developed. This study aimed to estimate the prevalence of CHG tolerance among S. aureus strains in Israel and to evaluate factors that may affect this tolerance. Furthermore, it tested the associations between phenotypic and genotypic CHG tolerance. S. aureus strains (n = 190) were isolated from clinical samples of patients admitted to various medical institutions in Israel. Phenotypic susceptibility to CHG was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Genotypic tolerance was detected using real-time PCR for detection of qac A/B genes. MIC for the antibiotic mupirocin was determined using the Etest method. Presence of the Panton–Valentine Leucocidin (pvl) toxin, mecA and mecC genes was detected using an eazyplex® MRSAplus kit (AmplexDiagnostics GmbH, Gars, Germany). CHG tolerance was observed in 13.15% of the isolates. An association between phenotypic and genotypic tolerance to CHG was observed. Phenotypic tolerance to CHG was associated with methicillin resistance but not with mupirocin resistance. Additionally, most of the CHG-tolerant strains were isolated from blood cultures. In conclusion, this work shed light on the prevalence of reduced susceptibility to CHG among S. aureus strains in Israel and on the characteristics of tolerant strains. CHG-tolerant strains were more common than methicillin-resistant ones in samples from invasive infections. Further research should be performed to evaluate risk factors for the development of CHG tolerance.

Assessment of Mupirocin Resistance among Clinical Isolates of Methicillin Resistant Staphylococcus aureus

Background: Methicillin-resistant Staphylococcus aureus (MRSA) colonization is considered a major risk factor for nosocomial infections and its decolonization has reduced these infections. Mupirocin (MUP) is the topical antibiotic of choice for decolonization. MUP decolonization failure is attributed to MUP resistance. Objective: The aim of the current study is to assess MUP resistance among MRSA isolates phenotypically and genotypically. Methodology: Fifty MRSA isolates were identified in Microbiology Department in the Medical Research Institute hospital, Alexandria University. Antibiotic susceptibility to different classes of antibiotics by disk diffusion method was done. MUP minimum inhibitory concentration (MIC) was determined phenotypically by MUP Ezy MIC™ Strips. MUP resistance was determined genetically by multiplex PCR detection of mupA and mupB. Results: Of all MRSA isolates, 6% exhibited high level and none showed low level MUP resistance. Only mupA was detected in all resistant isolates. Conclusion: Despite low prevalence of MUP resistance, it is appropriate to test MUP resistance prior nasal decolonization

Genotyping of methicillin resistant Staphylococcus aureus from the United Arab Emirates

Reports from Arabian Gulf countries have demonstrated emergence of novel methicillin resistant Staphylococcus aureus (MRSA) strains. To address the lack of data from the United Arab Emirates (UAE), genetic characterisation of MRSA identified between December 2017 and August 2019 was conducted using DNA microarray-based assays. The 625 MRSA isolates studied were grouped into 23 clonal complexes (CCs) and assigned to 103 strains. CC5, CC6, CC22 and CC30 represented 54.2% (n/N = 339/625) of isolates with other common CCs being CC1, CC8, CC772, CC361, CC80, CC88. Emergence of CC398 MRSA, CC5-MRSA-IV Sri Lanka Clone and ST5/ST225-MRSA-II, Rhine-Hesse EMRSA/New York-Japan Clone in our setting was detected. Variants of pandemic CC8-MRSA-[IVa + ACME I] (PVL+) USA300 were detected and majority of CC772 strains were CC772-MRSA-V (PVL+), “Bengal- Bay Clone”. Novel MRSA strains identified include CC5-MRSA-V (edinA+), CC5-MRSA-[VT + fusC], CC5-MRSA-IVa (tst1+), CC5-MRSA-[V/VT + cas + fusC + ccrA/B-1], CC8-MRSA-V/VT, CC22-MRSA-[IV + fusC + ccrAA/(C)], CC45-MRSA-[IV + fusC + tir], CC80-MRSA-IVa, CC121-MRSA-V/VT, CC152-MRSA-[V + fusC] (PVL+). Although several strains harboured SCC-borne fusidic acid resistance (fusC) (n = 181), erythromycin/clindamycin resistance (ermC) (n = 132) and gentamicin resistance (aacA-aphD) (n = 179) genes, none harboured vancomycin resistance genes while mupirocin resistance gene mupR (n = 2) and cfr gene (n = 1) were rare. An extensive MRSA repertoire including CCs previously unreported in the region and novel strains which probably arose locally suggest an evolving MRSA landscape.