Superoxide dismutase A (SodA) is a c-di-GMP effector protein governing oxidative stress tolerance in Stenotrophomonas maltophilia

C-di-GMP is a bacterial second messenger implicated in the regulation of many key functions including antibiotic tolerance and biofilm formation. Our understanding of how c-di-GMP exerts its action via receptors to modulate different biological functions is still limited. Here we used a c-di-GMP affinity pull-down assay coupled to LC-MS/MS to identify c-di-GMP-binding proteins in the opportunistic pathogen Stenotrophomonas maltophilia. This analysis identified Smlt3238 (SodA), a protein of the superoxide dismutase family, as a c-di-GMP-binding protein. Microscale thermophoresis showed that purified SodA protein bound c-di-GMP with an estimated dissociation constant (Kd) value of 141.5 μM. Using various in vivo and in vitro experiments, we demonstrated that c-di-GMP modulates the enzyme activity of SodA directly. Circular dichroism experiments revealed that SodA protein gradually altered its basic structure with increasing levels of c-di-GMP. Phenotypic experiments conducted in the presence of a range of intracellular c-di-GMP levels showed that SodA function is modulated by c-di-GMP. The findings thus identify a novel c-di-GMP binding protein that governs oxidative stress tolerance in S. maltophilia.

Genomic insights into the phage-defense systems of Stenotrophomonas maltophilia clinical isolates

Stenotrophomonas maltophilia is a rapidly evolving multidrug-resistant opportunistic pathogen that can cause serious infections in immunocompromised patients. Although phage therapy is one of promising strategies for dealing with MDR bacteria, the main challenges of phage therapeutics include accumulation of phage resistant mutations and acquisition of the phage defense systems. To systematically evaluate the impact of (pro)phages in shaping genetic and evolutionary diversity of S. maltophilia, we collected 166 S. maltophilia isolates from three hospitals in southern China to analyze its pangenome, virulence factors, prophage regions, and anit-viral immune systems. Pangenome analysis indicated that there are 1328 saturated core genes and 26961 unsaturated accessory genes in the pangenome, suggesting existence of highly variable parts of S. maltophilia genome. The presence of genes in relation to T3SS and T6SS mechanisms suggests the great potential to secrete toxins by the S. maltophilia population, which is contrary to the conventional notion of low-virulence of S. maltophilia. Additionally, we characterized the pan-immune system maps of these clinical isolates against phage infections and revealed the co-harboring of CBASS and anti-CBASS in some strains, suggesting a never-ending arms race and the co-evolutionary dynamic between bacteria and phages. Furthermore, our study predicted 310 prophage regions in S. maltophilia with high genetic diversity. Six viral defense systems were found to be located at specific position of the S. maltophilia prophage genomes, indicating potential evolution of certain site/region similar to bacterial 'defense islands' in prophage. Our study provides novel insights into the S. maltophilia pangenome in relation to phage-defense mechanisms, which extends our understanding of bacterial-phage interactions and might guide the application of phage therapy in combating S. maltophilia infections.

Cardiac manifestations of COVID-19 in Shenzhen, China

Purpose

The coronavirus disease 2019 (COVID-19) outbreak has become a global public health concern; however, relatively few detailed reports of related cardiac injury are available. The aims of this study were to compare the clinical and echocardiographic characteristics of inpatients in the intensive-care unit (ICU) and non-ICU patients.

Methods

We recruited 416 patients diagnosed with COVID-19 and divided them into two groups: ICU (n = 35) and non-ICU (n = 381). Medical histories, laboratory findings, and echocardiography data were compared.

Results

The levels of myocardial injury markers in ICU vs non-ICU patients were as follows: troponin I (0.029 ng/mL [0.007–0.063] vs 0.006 ng/mL [0.006–0.006]) and myoglobin (65.45 μg/L [39.77–130.57] vs 37.00 μg/L [26.40–53.54]). Echocardiographic findings included ventricular wall thickening (12 [39%] vs 1 [4%]), pulmonary hypertension (9 [29%] vs 0 [0%]), and reduced left-ventricular ejection fraction (5 [16%] vs 0 [0%]). Overall, 10% of the ICU patients presented with right heart enlargement, thickened right-ventricular wall, decreased right heart function, and pericardial effusion. Cardiac complications were more common in ICU patients, including acute cardiac injury (21 [60%] vs 13 [3%]) (including 2 cases of fulminant myocarditis), atrial or ventricular tachyarrhythmia (3 [9%] vs 3 [1%]), and acute heart failure (5 [14%] vs 0 [0%]).

Conclusion

Myocardial injury marker elevation, ventricular wall thickening, pulmonary artery hypertension, and cardiac complications including acute myocardial injury, arrhythmia, and acute heart failure are more common in ICU patients with COVID-19. Cardiac injury in COVID-19 patients may be related more to the systemic response after infection rather than direct damage by coronavirus.

Overview of antimicrobial options for Mycoplasma pneumoniae pneumonia: focus on macrolide resistance

BACKGROUND AND AIMS

Community-acquired pneumonia (CAP) is a common infectious disease affecting children and adults of any age. Mycoplasma pneumoniae has emerged as leading causative agent of CAP in some region, and the abrupt increasing resistance to macrolide that widely used for management of M. pneumoniae has reached to the level that it often leads to treatment failures.

OBJECTIVE

We aim to discuss the drivers for development of macrolide-resistant M. pneumoniae, antimicrobial stewardship and also the potential treatment options for patients infected with macrolide-resistant M. pneumonia.

METHODS

The articles in English and Chinese published in Pubmed and in Asian medical journals were selected for the review.

RESULTS

M. pneumoniae can develop macrolide resistance by point mutations in the 23S rRNA gene. Inappropriate and overuse of macrolides for respiratory tract infections may induce the resistance rapidly. A number of countries have introduced the stewardship program for restricting the use of macrolide. Tetracyclines and fluoroquinolones are highly effective for macrolide-resistant strains, which may be the substitute in the region of high prevalence of macrolide-resistant M. pneumoniae.

CONCLUSION

The problem of macrolide resistant M. pneumonia is emerging. Antibiotic stewardship is needed to inhibit the inappropriate use of macrolide and new antibiotics with a more acceptable safety profile for all ages need to be explored.

Epidemiology and genotype distribution of high risk human papillomavirus in population of hospital opportunistic screening

This study aimed to determine the prevalence of high-risk human papillomavirus (HR-HPV) in population of hospital opportunistic screening and to identify the correlation of prevalent genotypes and cervical cytological abnormalities. A cross-sectional study was employed between July 2013 and July 2014 in the Chaoyang hospital, in Beijing. Cervical samples were collected for the Type-specific HPV and the cervical cytological analyses in the population of hospital opportunistic screening. Total of 8975 samples from female patients aged 17-86 years were tested. Of these, 10.4% were infected by HR-HPV, the highest prevalence of HR-HPV in the youngest group and decreasing with aging (X(2)=19.68, P=0.02). Of these, 78.73% were single infections and 21.27% were multiple infections. Age-specific prevalence of multiple HPV exhibited a "U" shaped curve (X(2)=19.98, P=0.018). The most prevalent genotype is HPV 52, then descending order of frequency were HPV-58, 16, 39, 51, 56, 59, 18, 31, 33, 35, 68 and 45. 15.9% had an abnormal cytology in HR-HPV positive women, vs 4.13% in HR-HPV negative women. The prevalence of HR-HPV were 9.2%, 26.8%, 32%, 35.3% and 36.4% in normal cell, ASCUS, LSIL, ASC-H and HSIL, respectively (X(2)=234.67, P=0.000). Women with HPV 52, 16, 18, 58, 39, 51, 59, 56, 33, 31 infections related to the abnormal cytology, while the HPV68, 45, 35 didn't. The prevalent characteristic in population of the hospital opportunistic screening is similar to the population of cervical screen, But the most five prevalent genotype in rank are different .Women with HR-HPV infections were more likely to have the cervical abnormal cytology.

Viral etiology of community-acquired pneumonia among adolescents and adults with mild or moderate severity and its relation to age and severity

BACKGROUND

Better knowledge of distribution of respiratory viruses (RVs) in adolescents and adults with community-acquired pneumonia (CAP) is needed.

METHODS

To investigate the RVs etiology among adolescents and adults with CAP, according to age and pneumonia severity index (PSI), a multi-center, prospective study was conducted from November 2010 to April 2012. Fifteen RVs were tested by polymerase chain reaction (PCR). Bacteria were detected by urinary antigen, conventional culture and PCR.

RESULTS

Mean (SD) age and median (IQR) PSI score of 954 patients enrolled was 45.2 (19.5) years (range 14-94) and 42 (36). RVs were found in 262 patients (27.5%): influenza virus A (IFV A, 9.9%) comprised of pandemic H1N1 (6.7%) and seasonal H3N2 (3.5%), human rhinovirus (4.3%), adenovirus (4.2%), human metapneumovirus (1.8%), parainfluenza virus 1, 3 and 2 (1.7%, 1.5% and 1.2%). Influenza virus B, enterovirus, respiratory syncytial virus, human coronavirus and parainfluenza virus 4 were rarely detected (<1%). Frequency of IFV A was highest among patients aged between 45-64 years (p < 0.001), while adenovirus among patients aged 14-17 years (p < 0.001), no differences was found in other RVs. The proportion of pandemic H1N1 increased with severity of pneumonia evaluated by PSI (P < 0.05).

CONCLUSIONS

The proportion of RVs in CAP is higher than previously reported. IFV A pneumonia are usually found in patients older than 45 years, while, adenovirus pneumonia are common in adolescents and young adults. Pandemic H1N1 virus is still recognized by PSI as a high-severity pathogen. The findings contribute baseline data on viral CAP study in China.

Emergence of community-acquired adenovirus type 55 as a cause of community-onset pneumonia

BACKGROUND

Since 2008, severe cases of emerging human adenovirus (HAdV) type 55 (HAdV-55) were reported sporadically in China. But no comparative studies had been conducted to discern the differences in epidemiologic and clinical abnormalities between HAdV-55 and other types (HAdV-7, HAdV-3, HAdV-14, HAdV-50, and HAdV-C).

METHODS

A multicenter surveillance study for adult and adolescent community-acquired pneumonia (CAP) was conducted prospectively in Beijing and Yan Tai between November 2010 and April 2012. A standardized data form was used to record clinical information. The viral DNA extracted from the clinical samples or adenovirus viral isolates was sequenced.

RESULTS

Among 969 cases, 48 (5%) were identified as adenovirus pneumonia. Six branches were clustered: HAdV-55 in 21, HAdV-7 in 11, HAdV-3 in nine, HAdV-14 in four, HAdV-50 in two, and HAdV-C in one. Most HAdV-55 cases were identified during February and March. All the hypervariable regions of the hexon genes of the 21 HAdV-55 strains were completely identical. Patients who had HAdV-55 were about 10 years older ( P = .027) and had higher pneumonia severity index scores ( P = .030) compared with those with other types (HAdV-7, HAdV-3, HAdV-14, HAdV-50, and HAdV-C). Systemic BP was also higher among patients in the HAdV-55 group ( P = .006). Unilateral or bilateral consolidations were the most common radiologic findings in both patients with HAdV-55 and those with other types (57.9% vs 36%). More than one-half of the patients were admitted to hospital; oxygen therapy was given to 29.2% of the 48 patients, and two needed mechanical ventilation.

CONCLUSIONS

HAdV-55 has established itself as a major pneumonia pathogen in the Chinese population, and further surveillance and monitoring of this agent as a cause of CAP is warranted.