Prostatic Abscess Caused by Klebsiella pneumoniae: A 6-Year Single-Center Study

Analysis of virulence profiles in clinical isolates of Klebsiella pneumoniae from renal abscesses: clinical significance of hypervirulent isolates

Introduction

Klebsiella pneumoniae can cause a wide range of infections. Hypervirulent K. pneumoniae (hvKp), particularly associated with the K1 and K2 capsular types, is an increasingly significant microorganism with the potential to cause invasive infections, including renal abscesses. Despite the rising prevalence of hvKp infections, information on renal abscesses caused by K. pneumoniae is limited, and the clinical significance of hvKp associated with specific virulence genes remains elusive.

Methods

This study performed at a 1200-bed tertiary hospital sought to identify the clinical and microbiological characteristics of renal abscesses caused by K. pneumoniae, focusing on various virulence genes, including capsular serotypes and multilocus sequence typing (MLST).

Results

Over an 8-year period, 64 patients with suspected renal abscesses were reviewed. Ten patients diagnosed with K. pneumoniae-related renal abscesses were ultimately enrolled in the study. Among the isolates from the 10 patients, capsular serotype K2 was predominant (40.0%), followed by K1 (30.0%). The most common sequence type by MLST was 23 (40.0%). In particular, six patients (60.0%) harbored specific genes indicative of hvKp: iucA, peg-344, rmpA, and rmpA2.

Conclusions

Our findings highlight the importance of hvKp as a pathogen in renal abscesses. Although the nature of hvKp is relatively unknown, it is widely recognized as a highly virulent pathogen that can infect relatively healthy individuals of various ages and simultaneously cause infections at multiple anatomical sites. Therefore, when treating patients with K. pneumoniae-related renal abscesses, caution is necessary when considering the characteristics of hvKp, such as potential bacteremia, multi-organ abscess formation, and metastatic spread.

Evaluating the incidence of ampC-β-lactamase genes, biofilm formation, and antibiotic resistance among hypervirulent and classical Klebsiella pneumoniae strains

AIM

Both immunocompetent and healthy individuals can become life-threateningly ill when exposed to the hypervirulent (hvKp) strains of Klebsiella pneumoniae (Kp). The main objectives of this study were to evaluate the presence of ampC-lactamase genes, biofilm formation, and antibiotic resistance in clinical strains of hvKp and cKp (classical K. pneumoniae).

MATERIALS AND METHODS

Kp strains were collected from patients referred to Shahidzadeh Hospital in Behbahan City, Khuzestan Province, Iran. Several techniques were used to identify hvKp. The hypermucoviscosity phenotype was determined using the string test. Isolates that developed dark colonies on tellurite agar were assumed to be hvKp strains. If any of the iucA, iutA, or peg-344 genes were detected, the isolates were classified as hvKp. Phenotypic and genotypic detection of AmpC β-lactamases of hvKp strains was performed by the combined disk method and polymerase chain reaction, respectively. In addition, crystal violet staining was used to determine the biofilm formation of these isolates.

RESULTS

For this study, 76 non-duplicative isolates of Kp were collected. Overall, 22 (28.94%) strains had positive string test results, and 31 (40.78%) isolates were grown in tellurite-containing medium. The genes iucA and iutA or peg-344 were found in 23.68% of all Kp strains and in 50% of tellurite-resistant isolates, respectively. The most effective antibiotics against hvKp isolates were tetracycline (85.52%) and chloramphenicol (63.15%). Using the cefoxitin disc diffusion method, we observed that 56.57% (43/76) of the strains were AmpC producer. A total of 30.26% (n = 23/76) of the isolates tested positive for at least one ampC gene, including blaDHA (52.63%, n = 40), blaCIT (40.78%, n = 31), blaACC (19.76%, n = 15), blaMOX (25%, n = 19), and blaFOX (43.42%, n = 33). Biofilm formation analysis revealed that most hvKp isolates were weak (n = 6, 40%) and moderate (n = 5, 33.33%) biofilm producers.

CONCLUSION

Healthcare practitioners should consider the possibility of the existence and acquisition of hvKp everywhere. The exact mechanisms of bacterial acquisition are also unknown, and it is unclear whether the occurrence of infections is related to healthcare or not. Thus, there are still many questions about hvKp that need to be investigated.

Coinfection with Hypervirulent Klebsiella pneumoniae and Aspergillus flavus in a Critically Ill Patient with Aspergillus Overlap Syndrome: A Case Report

Pulmonary aspergillosis is generally categorized into three groups: allergic bronchopulmonary aspergillosis, chronic pulmonary aspergillosis and invasive pulmonary aspergillosis. Aspergillus overlap syndromes (AOS) defined as the occurrence of more than one form of aspergillus disease in a single individual is not common. We present a 62-year-old-male patient with tachypnea, hypoxemia and shock after 4 weeks of cough, expectoration and intermittent hemoptysis, and 2 days of hyperpyrexia. Cardiac arrest occurring during tracheal intubation was resuscitated successfully. Laboratory examination showed acute kidney failure and severe myelosuppression with leukopenia and thrombocytopenia. Chest computed tomography (CT) scan showed the cavity with aspergilloma in the right upper lung lobe, a mass of consolidation in the right lower lung lobe and hyperdense shadow bronchiectasis in the left lower lobe. Bronchoscopy showed lots of sputum occluding the opening of the right airway bronchus. Laboratory examination showed significantly increased C-reactive protein (CRP) and procalcitonin concentration, serum (1,3)-β-D-glucan (BDG) and aspergillus immunoglobulin G (IgG) levels were also elevated. The metagenomic next-generation sequencing and sputum cultures revealed Klebsiella pneumoniae and Aspergillus flavus infection. Pulmonary aspergillosis, invasive aspergillosis infection and severe pneumonia were diagnosed. Initial caspofungin and meropenem followed by piperacillin-tazobactam sodium and voriconazole were administrated in combination. Continuous renal replacement therapy and mechanical ventilation were also performed. The patient's condition gradually recovered. Oral antifungal therapy was continued for 1 year after discharge and CT images gradually improved. Coinfections with K. pneumoniae and A. flavus in a patient with AOS will complicate clinical conditions. A search of PubMed showed few reports of similar cases. Clinicians should pay enough attention to the polymicrobial interactions and improve clinical management strategies, especially in critically ill patient with AOS.

Beta-lactamase determinants and molecular typing of carbapenem-resistant classic and hypervirulent Klebsiella pneumoniae clinical isolates from southwest of Iran

This study investigated the molecular epidemiology of carbapenem-resistant classic Klebsiella pneumoniae (CR-cKp) and carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) isolates in southwestern Iran. From 2019 to 2021, 136 (88.9%) cKp and 17 (11.1%) hvKp isolates were identified using biochemical tests and polymerase chain reaction (PCR). Antibiotic resistance, beta-lactamases, and clonal relatedness of carbapenem-resistant isolates were investigated using disk diffusion, PCR, and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), respectively. The different markers of hvKp isolates were as follows: string test (35.3%, n = 6/17), magA (11.8%, n = 2/17), rmpA (11.8%, n = 2/17), rmpA2 (52.9%, n = 9/17), iucA (52.9%, n = 9/17), and peg344 (35.3%, n = 6/17). Also, 55.1% (n = 75/136) of cKp and 47.1% (n = 8/17) of hvKp isolates were CR-cKp and CR-hvKp, respectively. All CR-hvKp (100.0%, n = 8) isolates were MDR. Colistin, tetracycline, and tigecycline were the most effective antibiotics. The occurrence of beta-lactamase genes in 75 CR-cKp and 8 CR-hvKp isolates was as follows: bla NDM (41.3, 25.0%), bla IMP (4.0, 0.0%), bla VIM (8.0, 0.0%), bla GES (14.7, 25.0%), bla OXA-48-like (20.0, 0.0%), bla CTX-M (26.7, 12.5%), bla SHV (24.0, 12.5%), bla TEM (10.7, 0.0%), bla FOX (6.7, 0.0%), bla DHA (6.7, 0.0%), bla CMY (5.3, 0.0%), bla LAT (12.0, 0.0%), and bla ACT (8.0, 0.0%). ERIC-PCR showed a high diversity among isolates. In this study, the occurrence of MDR CR-hvKp isolates harboring bla NDM and bla GES was detected for the first time in southwestern Iran. To prevent the spread of CR-hvKp and reduce selection pressure, long-term surveillance and more effective treatment strategies should be implemented.