An outbreak of severe infectious diseases caused by methicillin-resistant Staphylococcus aureus USA300 clone among hospitalized patients and nursing staff in a tertiary care university hospital

Reservoirs of Nosocomial Pathogens in Intensive Care Units: A Systematic Review

Background

Nosocomial pathogens are known to exacerbate morbidity and mortality in contemporary critical healthcare. Hospital fomites, which include inanimate surfaces, have been identified as "breeding grounds" for pathogens that cause nosocomial infections. This systematic review aimed to deliver incisive insights on nosocomial pathogens in intensive care units (ICUs) and the role of fomites as potential reservoirs for their transmission.

Method

An extensive exploration of electronic databases, including PubMed and Scopus, from 1990 to 2023, was carried out between 25th and 29th May 2023, per standard PRISMA guidelines. Information were extracted from articles that reported on fomites in the ICU. Studies that did not quantitatively report the fomite contamination, and those that exclusively took samples from patients in the ICU were excluded from the analysis.

Results

About 40% of the total samples collected on fomites from all the studies yielded microbial growth, with species of Staphylococcus being the most predominant. Other prevalent microbes were Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Candida spp., Enterococcus sp., and Enterobacter sp. The neonatal intensive care unit (NICU) had the highest proportion of contaminated fomites. Among known fomites, the sphygmomanometer exhibited a 100% detection rate of nosocomial pathogens. This included E. aerogenes, Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), E. coli, and K. pneumoniae. Multidrug-resistant (MDR) bacteria, such as methicillin-resistant S. aureus (MRSA), vancomycin-resistant Enterococci (VRE), extended-spectrum beta-lactamase (ESBL)-producing E. coli, and MDR Pseudomonas aeruginosa were commonly isolated on fomites in the ICUs.

Conclusion

Many fomites that are readily used in patient care in the ICU harbour nosocomial pathogens. The most common fomite appeared to be mobile phones, sphygmomanometers, and stethoscopes, with Staphylococcus being the most common contaminant. Consequently, the need for rigorous disinfection and sterilization protocols on fomites in the ICU cannot be overemphasized. Additionally, heightened awareness on the subject among health professionals is crucial to mitigating the risk and burden of nosocomial infections caused by drug-resistant bacteria.

Whole-genome sequencing links cases dispersed in time, place, and person while supporting healthcare worker management in an outbreak of Panton-Valentine leucocidin meticillin-resistant Staphylococcus aureus; and a review of literature

This is a report on an outbreak of Panton-Valentine leucocidin-producing meticillin-resistant Staphylococcus aureus (PVL-MRSA) in an intensive care unit (ICU) during the COVID-19 pandemic that affected seven patients and a member of staff. Six patients were infected over a period of ten months on ICU by the same strain of PVL-MRSA, and a historic case identified outside of the ICU. All cases were linked to a healthcare worker (HCW) who was colonized with the organism. Failed topical decolonization therapy, without systemic antibiotic therapy, resulted in ongoing transmission and one preventable acquisition of PVL-MRSA. The outbreak identifies the support that may be needed for HCWs implicated in outbreaks. It also demonstrates the role of whole-genome sequencing in identifying dispersed and historic cases related to the outbreak, which in turn aids decision-making in outbreak management and HCW support. This report also includes a review of literature of PVL-MRSA-associated outbreaks in healthcare and highlights the need for review of current national guidance in the management of HCWs' decolonization regimen and return-to-work recommendations in such outbreaks.

Emergence of community-associated methicillin-resistant Staphylococcus aureus ΨUSA300 among Japanese people with HIV, resulted from stepwise mutations in 2010s

Although infection with the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 is extremely rare in Japan, the uniquely evolved clone ΨUSA300 has been reported in Japan. An outbreak of a distinct USA300 clone was recently reported in an HIV/AIDS referral hospital in Tokyo. The present study investigated the evolutionary origin and genetic diversity of USA300-related clones causing regional outbreaks among people living with HIV (PLWHIV) in Tokyo. MRSA isolates collected from PLWHIV in an HIV/AIDS referral center in Tokyo were subjected to whole-genome sequencing and their genetic features were compared with those of previously described USA300 MRSA genomes. Of the 28 MRSAs isolated in 2016-2019, 23 (82.1%) were identified as USA300, with 22 (95.6%) of the latter identified as ΨUSA300. Although the genomic structure of ΨUSA300 was identical to the structures of reference USA300 strains, one clade (cluster A) was found to have acquired 29 previously identified lineage-specific mutations in a stepwise manner. The estimated divergence dates of ΨUSA300 and Cluster A were 2009 and 2012, respectively. These findings suggested that the ΨUSA300 clone had spread among PLWHIVs in Tokyo in the early 2010s, with stepwise acquisition of lineage-specific nonsynonymous mutations.

Dissemination of methicillin-resistant Staphylococcus aureus USA300 ST8/PVL- positive in breast infections in a Brazilian region

We aimed to analyze the molecular epidemiology of 46 methicillin-resistant Staphylococcus aureus (MRSA) isolated from breast infections. The USA300 lineage carrying SCCmecIVa, arginine catabolic mobile element, t008, ST8, and Panton-Valentine leukocidin genes was predominant (93%). This is the first study that describes the spread of the USA300 methicillin-resistant Staphylococcus aureus clone in breast infections in Brazil.

Complete Genome Sequencing of a Community-Associated Methicillin-Resistant Staphylococcus aureus ψUSA300 Strain JICS127, a Uniquely Evolved USA300 Lineage in Japan

A ψUSA300 clone of MRSA, a derivative of USA300, is uniquely found in Japan and has 12-bp deletion on ccrB2 in type IVa staphylococcal cassette chromosome mec element. We hereby present the complete genome of ψUSA300 strain JICS127.

Clinical features and antimicrobial treatment of skin infections caused by Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus

Skin infections caused by Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA), especially the USA300 clone, have been increasing in Japan. To prevent an epidemic of PVL-positive MRSA, rapid diagnosis and effective antimicrobial therapy are essential. However, the clinical features of, and antimicrobial efficacy against, these skin infections are not well understood in Japan. Here, we report 10 cases of skin infections caused by PVL-positive MRSA that presented over a two-year period in our clinic. Genetic analyses revealed that 90% of the PVL-positive MRSA strains were identified as USA300 and its related clones. Notably, 70% of the patients had atopic dermatitis (AD) as an underlying disease. Average durations of antimicrobial therapy for AD patients (10.6 weeks) were 2.9-fold longer than those for non-AD patients (3.7 weeks). However, all cases were improved by a long-term course of fosfomycin, minocycline, doxycycline, and/or rifampicin. Our data suggest that AD may be an important risk factor for intractable skin infections caused by PVL-positive MRSA.

Staphylococcus aureus-targeting peptide/surfactant assemblies for antibacterial therapy

To address the challenge from microbial resistance, this work developed a surfactant with 18-carbon single hydrocarbon chain and multi-amine head groups (C18N3). After assembling with Staphylococcus aureus-targeting peptide (CARG), the obtained C18N3/CARG assemblies exhibited excellent antimicrobial activities against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in vitro and in vivo, in which the targeting peptide CARG bonded specifically to Staphylococcus aureus and C18N3 killed bacteria with a mechanism of membrane disruption. Importantly, C18N3 could also work as a β-lactamase inhibitor to overcome the bacterial resistance to β-lactam antibiotics through noncompetitive inhibition. The combination of β-lactam antibiotic and C18N3/CARG assemblies more effectively suppressed methicillin-resistant Staphylococcus aureus in vitro and in vivo relative to equivalent dose of free antibiotic or C18N3. Thus, the antibacterial platform of antibiotic-carrying surfactant assemblies bearing bacteria-targeted peptides, in which C18N3 performed dual function, antibacterial agent and β-lactamase inhibitor, may help fight against the difficult-to-treat infections.

Infection control measures in nosocomial MRSA outbreaks-Results of a systematic analysis

There is a lack of data on factors that contribute to the implementation of hygiene measures during nosocomial outbreaks (NO) caused by Methicillin-resistant Staphylococcus aureus (MRSA). Therefore, we first conducted a systematic literature analysis to identify MRSA outbreak reports. The expenditure for infection control in each outbreak was then evaluated by a weighted cumulative hygiene score (WCHS). Effects of factors on this score were determined by multivariable linear regression analysis. 104 NO got included, mostly from neonatology (n = 32), surgery (n = 27), internal medicine and burn units (n = 10 each), including 4,361 patients (thereof 657 infections and 73 deaths) and 279 employees. The outbreak sources remained unknown in 10 NO and were not reported from further 61 NO. The national MRSA prevalence did not correlate with the WCHS (p = .714). There were significant WCHS differences for internal medicine (p = 0.014), burn units (p<0.01), for Japanese NO (p<0.01), and NO with an unknown source (p<0.01). In sum, management of a NO due to MRSA does not depend on the local MRSA burden. However, differences of MRSA management among medical departments do exist. Strict adherence to the Outbreak Reports and Intervention Studies Of Nosocomial infection (ORION) statement is highly recommended for. The WCHS may also serve as a useful tool to quantify infection control effort and could therefore be used for further investigations.

Prevalence and Characterization of Methicillin-Resistant Staphylococcus aureus from Community- and Hospital-Associated Infections: A Tertiary Care Center Study

The community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has become increasingly prevalent in both community and hospital settings. The aim of this study was to determine the prevalence, molecular characteristics and antibiotic resistance profiles of CA-MRSA from community- and hospital-associated infections in a tertiary care hospital in Mangalore, India. Of 520 S. aureus isolates, 362 were from inpatients (IP) and 158 were from outpatients (OP). One-hundred and thirty-two MRSA isolates obtained from 94 inpatients and 38 outpatients with complete clinical details were further analyzed. Of these, 81 (61.4%) were CA-MRSA (IP-47.9%, OP-94.7%) and 51 (38.6%) were HA-MRSA (IP-52.1%, OP-5.3%). All (100%) MRSA isolates were mecA gene positive. SCCmec typing identified SCCmec type IV (50.6%) and SCCmec type V (66.7%) in CA-MRSA, while SCCmec type I (41.2%), SCCmec type III (19.6%), SCCmec type IV (31.4%) and SCCmec type V (25.5%) were detected in HA-MRSA isolates. The Panton–Valentine Leukocidin (PVL) gene was found in 70.4% of CA-MRSA, 43.1% of HA-MRSA with SCCmec type IV and SCCmec type V, and in 7.8% of true HA-MRSA. The antibiotic resistance profiles were determined by the disc diffusion method. Resistance to cefoxitin was used to identify MRSA. A significant difference (p < 0.05) was observed between CA-MRSA and HA-MRSA with respect to resistance against cephalexin, cefotaxime, levofloxacin, linezolid and teicoplanin. CA-MRSA was predominantly resistant to ciprofloxacin (86.4%), erythromycin (66.7%), ofloxacin (49.4%), cefotaxime (44.4%), gentamicin (40.7%) and clindamycin (40.7%), while HA-MRSA showed resistance against ciprofloxacin (80.4%), erythromycin (80.1%), cefotaxime (70.6%),ofloxacin (58.8%), clindamycin (47.1%) and levofloxacin (41.2%).This study reports the prevalence of CA-MRSA in community and hospital settings and the possibility of multidrug-resistant CA-MRSA replacing HA-MRSA in hospitals. The observations from our study emphasize the need for urgent measures to manage this emerging crisis in healthcare settings.

[Antimicrobial Resistance and Infection Control for Gram-positive Bacteria]

Antimicrobial resistance (AMR) is a serious problem worldwide. We searched for the AMR determinants of various bacteria isolated from clinical settings and studied their resistance mechanisms and molecular epidemiology. This review focuses on the AMR of Staphylococcus aureus, a major gram-positive pathogen, which has the ability to acquire resistance to antimicrobials. The resistance factors of S. aureus are frequently found on mobile elements, including plasmids and transposons. We determined the complete DNA sequence of the tetracycline-resistance plasmid and found that the inducible expression of tetK in S. aureus was regulated by a post-transcriptional attenuation mechanism. Furthermore, outbreaks of methicillin-resistant S. aureus (MRSA) in hospitals and communities have led us to study infection controls, including the antiseptic susceptibility evaluation and molecular epidemiology of MRSA. Various antiseptic resistance determinants, such as qacA/B and smr, were identified on plasmids and characterized. We demonstrated that the plasmid-mediated efflux pump QacB variant QacIII confers fluoroquinolone efflux ability to S. aureus. Studies on MRSA epidemiology had shown that community-acquired MRSA (CA-MRSA) was disseminated into hospitals and that an increased use of alcohol-based rubs could reduce the incidence of MRSA infections in such institutions. Additionally, the study of CA-MRSA collected from communities and hospitals showed an increase in Panton-Valentine leucocidin (PVL)-positive CA-MRSA, causing severe skin and soft tissue infections. Moreover, various PVL-positive CA-MRSA clones have disseminated in Japan, whereas the USA300 LV/J clone evolved in that country. Our study provides important information regarding MRSA infection control.

A Murine Skin Infection Model Capable of Differentiating the Dermatopathology of Community-Associated MRSA Strain USA300 from Other MRSA Strains

USA300 is a predominant and highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain that is a leading cause of skin and soft tissue infections. We established a murine intradermal infection model capable of demonstrating dermatopathological differences between USA300 and other MRSA strains. In this model, USA300 induced dermonecrosis, uniformly presenting as extensive open lesions with a histologically documented profound inflammatory cell infiltrate extending below the subcutis. In contrast, USA400 and a colonizing control strain M92 caused only localized non-ulcerated skin infections associated with a mild focal inflammatory infiltrate. It was also determined that the dermonecrosis induced by USA300 was associated with significantly increased neutrophil recruitment, inhibition of an antibacterial response, and increased production of cytokines/chemokines associated with disease severity. These results suggest that induction of severe skin lesions by USA300 is related to over-activation of neutrophils, inhibition of host antibacterial responses, and selective alteration of host cytokine/chemokine profiles.

An Outbreak of USA300 Methicillin-Resistant Staphylococcus aureus Among People With HIV in Japan

BACKGROUND

USA300 produces Panton-Valentin leucocidin (PVL) and is known as a predominant community-associated methicillin-resistant Staphylococcus aureus (MRSA) strain in the United States, but it was extremely rare in Japan. We report here an outbreak of USA300 in people with HIV (PWH) in Tokyo, Japan.

METHODS

We analyzed the cases of PVL-MRSA infection between 2010 and 2020 and screened for nasal colonization of PVL-MRSA in PWH who visited an HIV/AIDS referral hospital from December 2019 to March 2020. Whole-genome sequencing-based single nucleotide polymorphism (SNP) analysis was performed on these isolates.

RESULTS

During the study period, a total of 21 PVL-MRSA infections in 14 patients were identified after 2014. The carriage prevalence was 4.3% (12/277) and PVL-MRSA carriers were more likely to have sexually transmitted infections (STIs) within a year compared with patients who had neither a history of PVL-MRSA infection nor colonization (33.3% [4/12] vs 10.1% [26/258]; P = .03). SNP analysis showed that all 26 isolates were ST8-SCCmecIVa-USA300. Twenty-four isolates were closely related (≤100 SNP differences) and had the nonsynonymous SNPs associated with carbohydrate metabolism and antimicrobial tolerance.

CONCLUSIONS

An outbreak of USA300 has been occurring among PWH in Tokyo and a history of STI was a risk of colonization.

Clinically Important Toxins in Bacterial Infection: Utility of Laboratory Detection

The elaboration of proteins that damage host cells is fundamental to the pathogenesis of many bacterial pathogens. The clinical significance of many bacterial toxins is well recognized, and routine detection is necessary to confirm definitive diagnosis for some types of infectious diseases. Determining the clinical significance of a toxin involves many factors, including the toxin's prevalence, virulence, and role in disease pathogenesis. While essential from a diagnostic perspective, toxin detection has the potential to be important for patient management decision making, as well as infection prevention and control measures. This review focuses on the history, epidemiology, pathogenesis, clinical presentation, and management of infections associated with well-defined, clinically important toxins (such as Shiga toxin-producing Escherichia coli), as well as those that are less well defined (such as Staphylococcus aureus' Panton-Valentine leukocidin) where detection may yield clinically important information.

Prevalence and antibiogram of coagulase negative Staphylococci in bioaerosols from different indoors of a university in India

BACKGROUND

Staphylococci species are the major constituents of infectious bioaerosols, particularly methicillin-resistant Staphylococci (MRS) have serious health impacts. Here, the bacterial burden was quantified, especially prevalence of MRS in bioaerosols collected from indoors of Dr. B.R. Ambedkar Central Library (DBRACL) and Central Laboratory Animal Resources (CLAR) of Jawaharlal Nehru University, New Delhi, India. Air samplings from DBRACL and CLAR were done using the settle plate method and SKC biosampler, respectively.

RESULTS

This study showed a maximum 6757 CFU/m²/hr of bacterial load in the DBRACL reading room, while unacceptable bacterial loads (> 1000 CFU/m³ of air) at different sites of CLAR. Further, at both the sampling sites the predominance of coagulase negative Staphylococci (CNS) was observed. A total 22 and 35 Staphylococci isolates were isolated from DBRACL and CLAR bioaerosols, respectively. Majority (16/22) of the Staphylococcal isolates from DBRACL belonged to human-associated Staphylococci where S. haemolyticus (5/22) was the most dominating species. However, in CLAR facility centre, animal-associated Staphylococci (19/35) were dominating, where S. xylosus (12/35) was the most dominating species. Further, antibiotic sensitivity tests revealed 41% MRS and 73% multidrug resistant (MDR) among airborne Staphylococci from DBRACL indoor bioaerosols. Similarly, in CLAR facility, approximately, 66% Staphylococci isolates were methicillin resistant, out of which 2 isolates showed high MIC value ≥ 16 μg/mL. Further, we confirmed the presence of 49% multidrug resistant Staphylococci in the indoor air of CLAR facility.

CONCLUSIONS

This study suggested that the exposure of workers and students in CLAR to such a high concentration of drug-resistant Staphylococci should not be undermined, as these bacterial concentrations are the direct representative of inhalable particulate matter (PM_2.5) as per collection procedure. Simultaneously, passive sampling from DBRACL assessed the risks due to microbial contamination in particle agglomerates, which may deposit on the crucial surfaces such as wounds/ cuts or on the frequently used items.

A risk as an infection route: Nasal colonization of methicillin-resistant Staphylococcus aureus USA300 clone among contact sport athletes in Japan

Panton-Valentine leukocidin (PVL)-positive USA300 clone is a highly pathogenic and global epidemic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone. Athletes are particularly vulnerable to CA-MRSA infection because of the frequency of skin trauma, close-contact situations, and sharing of equipment that is customary in the athletic setting. We experienced a case of Japanese collegiate football player with septic pulmonary emboli secondary to infectious iliofemoral deep venous thrombosis caused by the USA300 clone. Here, we screened the nasal carriage of USA300 clone colonization among asymptomatic teammate of the patient to elucidate the infection route. Among 69 nasal samples, CA-MRSA strains were found in 5.8% (four samples). Molecular epidemiological analyses showed that three of the CA-MRSA strains were USA300 clone. Furthermore, pulsed-field gel electrophoresis revealed that all nasal USA300 clones showed 100% identity with the USA300 clone isolated from their teammate with critical infection. Our findings indicate that nasal colonization of the PVL-positive CA-MRSA, especially USA300 clone, pose a threat among contact sport athletes in Japan likewise other countries. An immediate infection control strategy for contact sport athletes is necessary to prevent outbreaks of PVL-positive CA-MRSA infections.

First Report of Fatal Infection Caused by Community-acquired Methicillin-resistant Staphylococcus aureus USA300 Clone in a Collegiate Athlete

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is prevalent around the world and is a causative agent of skin and soft tissue infections in healthy individuals. Particularly, Panton-Valentine leukocidin (PVL)-positive CA-MRSA strains occasionally cause life-threatening infections, such as septic pulmonary emboli (SPE) and infectious endocarditis. However, severe infections caused by PVL-positive CA-MRSA strains have rarely been reported in Japan. For the first time, this study reports the case of a 20-year-old Japanese college athlete with life-threatening PVL-positive CA-MRSA USA300 clone infection, including sepsis, SPE, and skin and soft tissue infections with iliofemoral deep venous thrombosis.