Staphylococcus aureus nasal carriage in health care workers: First report from a major public hospital in Argentina

Adaptation of Bacteria to Antineoplastic Agents Involves Persister Cells and Increases Resistance to Antibiotics

The increasing number of life-threatening infections observed in cancer patients has been ascribed to chemotherapy-induced neutropenia and to invasive medical procedures such as surgery and the application of catheters. In this study, it was questioned if the infections could also be favored by an increased resistance of bacteria due to the adaptation to antineoplastic agents used in chemotherapy. After exposure to several antineoplastic agents, it was observed that cells of Staphylococcus aureus, Mycobacterium vaccae, Pseudomonas aeruginosa, and Escherichia coli changed the fatty acid profile of their cellular membranes, produced exopolymeric substances, and formed aggregates that adhered to surfaces. Additionally, when exposed to high concentrations of these compounds, a persister sub-population could be identified. After adaptation to antineoplastic agents, the minimum inhibitory concentration (MIC) of several antibiotics increased considerably in the tested strains.

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.

Nasal Carriage of Methicillin-Resistant Staphylococcus aureus among Healthcare Workers in a Tertiary Care Hospital, Kathmandu, Nepal

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of nosocomial infections. One of the potential risk factors for nosocomial staphylococcal infections is colonization of the anterior nares of healthcare workers (HCWs). Our study aimed to determine the rate of nasal carriage MRSA among HCWs at Manmohan Memorial Medical College and Teaching Hospital, Kathmandu.

Methods

Two hundred and thirty-two nasal swabs were collected from HCWs of Manmohan Memorial Medical College and Teaching Hospital, Kathmandu, Nepal, within six months (February 2018-July 2018). Nasal swabs were cultured, and S. aureus isolates were subjected to the antimicrobial susceptibility test by the modified Kirby-Bauer disc diffusion method. MRSA and iMLSB (inducible macrolide lincosamide streptogramin B) resistance was screened using the cefoxitin disc (30 μg) and D-test (clindamycin and erythromycin sensitivity pattern), respectively, following CLSI (Clinical and Laboratory Standard Institute) guidelines. Risk factors for MRSA colonization were determined using the chi-square test considering the p value ˂0.05 as significant.

Results

A total of 34/232 (14.7%) S. aureus were isolated, out of which 12 (35.3%) were MRSA. The overall rate of nasal carriage MRSA among HCWs was 5.2% (12/232). Colonization of MRSA was higher in males (8.7%) than in females (4.3%). MRSA colonization was found to be at peak among the doctors (11.4%). HCWs of the postoperative ward were colonized highest (18.2%). All MRSA isolates were sensitive to linezolid and tetracycline. iMLSB resistance was shown by 7(20.6%) of the isolates. MRSA strains showed higher iMLSB resistance accounting for 33.3% (4/12) in comparison to methicillin-susceptible strains with 13.6% (3/22). Smoking was found to be significantly associated with MRSA colonization (p=0.004).

Conclusion

Rate of nasal carriage MRSA is high among HCWs and hence needs special attention to prevent HCW-associated infections that may result due to nasal colonization.

The relationship between hand hygiene practices and nasal Staphylococcus aureus carriage in healthcare workers

Background:

The nasal carriage rate of Staphylococcus aureus in healthcare workers (HCWs) is higher than the general population. Their hands serve as vectors for transmitting S.aureus colonized in the nose to patients.

Objectives:

To determine the rate of nasal S.aureus carriage and methicillin resistance in HCWs and to evaluate the relationship between carriage and personal risk factors and hand hygiene behaviors.

Methods:

The questionnaire included questions about sociodemographic characteristics, occupational and personal risk factors for S.aureus carriage, the “Hand Hygiene Belief Scale (HHBS),” and “Hand Hygiene Practices Inventory (HHPI)”. Nasal culture was taken from all participants. Presence of S.aureus, methicillin and mupirocin resistance were investigated in samples.

Results:

The study was carried out with 269 HCWs. The prevalence of S.aureus carriage was 20.1% (n:54). Among 54 S.aureus carriers, only one person had MRSA (0.37%). All S.aureus isolates were susceptible to mupirocin. S.aureus carriage was found to be significantly lower in the smoker group (p:0.015) and in the personnel wearing gloves during the procedures of each patient (p:0.002). S.aureus culture positivity was found to decrease significantly with increasing handwashing frequency (p:0.003). The mean HHPI score was higher in women (p:0.001). The mean HHPI score was lower in the group with nasal carriers than in non-carriers (p:0.176).

Conclusion:

The knowledge of hand hygiene practices, high frequency of handwashing, and wearing different gloves during the procedure of each patient decrease S.aureus nasal carriage in HCWs. In addition mupirocin is still effective in nasal S.aureus carriers.

The effect of fennel essential oil and trans-anethole on antibacterial activity of mupirocin against Staphylococcus aureus isolated from asymptomatic carriers

Introduction

Staphylococcus aureus constitutes the most pathogenic species within the staphylococcal genus. Humans remain the major reservoirs of this pathogen which colonizes mostly anterior nares of healthy individuals.

Aim

To investigate the effect of fennel essential oil (FEO) and trans-anethole (tA) on antibacterial activity of mupirocin (MUP) against S. aureus strains isolated from asymptomatic carriers.

Material and methods

The content of the FEO was analysed with use of the GC-MS method. The research done on 43 S. aureus isolates with different resistance patterns, obtained from nasal vestibule. Antibacterial activity of MUP in combination with FEO or tA was examined using the agar dilution method and E-test method. The data analysis was done with the Pearson’s χ² test.

Results

The chemical composition of FEO was consistent with the European Pharmacopoeia (EP) for the main constituent – tA (77.9%) according to the EP recommendations. Macrolide-lincosamide-streptogramin B resistance phenotype was prevalent among 39.5% of S. aureus isolates. FEO concentrations of 2.0% and 2.5% revealed antibacterial activity against 76.7% of isolates, whereas tA inhibited S. aureus growth at concentrations > 4.0%. The MIC values for MUP combined with FEO as well as for MUP combined with tA were < 0.064 µg/ml for 79.1% and 86.0% of S. aureus isolates, respectively.

Conclusions

Our experiment revealed FEO and tA influence on MUP effectiveness. The combination of MUP with FEO as well as MUP with tA are worth considering to implement in S. aureus eradication procedures. These findings will be useful in designing efficient antistaphylococcal agents which can limit the emergence of antibiotic resistance.

Broad-range lytic bacteriophages that kill Staphylococcus aureus local field strains

Staphylococcus aureus is a very successful opportunistic pathogen capable of causing a variety of diseases ranging from mild skin infections to life-threatening sepsis, meningitis and pneumonia. Its ability to display numerous virulence mechanisms matches its skill to display resistance to several antibiotics, including β-lactams, underscoring the fact that new anti-S. aureus drugs are urgently required. In this scenario, the utilization of lytic bacteriophages that kill bacteria in a genus -or even species- specific way, has become an attractive field of study. In this report, we describe the isolation, characterization and sequencing of phages capable of killing S. aureus including methicillin resistant (MRSA) and multi-drug resistant S. aureus local strains from environmental, animal and human origin. Genome sequencing and bio-informatics analysis showed the absence of genes encoding virulence factors, toxins or antibiotic resistance determinants. Of note, there was a high similarity between our set of phages to others described in the literature such as phage K. Considering that reported phages were obtained in different continents, it seems plausible that there is a commonality of genetic features that are needed for optimum, broad host range anti-staphylococcal activity of these related phages. Importantly, the high activity and broad host range of one of our phages underscores its promising value to control the presence of S. aureus in fomites, industry and hospital environments and eventually on animal and human skin. The development of a cocktail of the reported lytic phages active against S. aureus–currently under way- is thus, a sensible strategy against this pathogen.