Influence of the bacterial phenotypes on the clinical manifestations in Klebsiella pneumoniae bacteremia patients: A retrospective cohort study

Severe disseminated infection by hypermucoviscous Klebsiella pneumoniae successfully treated by intensive therapy with continuous hemodiafiltration using AN69ST: A case report and review of the literature

Klebsiella pneumoniae (Kpn) is one of the most common gram-negative bacilli causing lung, urinary tract, and biliary tract infections. However, as a distinct entity from classic Kpn, hypervirulent Kpn causing liver abscess, endophthalmitis, and lung abscess with poor prognoses has been reported mainly in East and Southeast Asia since the mid-1980s. Although the definition of hypervirulent Kpn is unclear, the hypermucoviscosity of Kpn is considered an important feature of hypervirulence. We present a case of emphysematous pyelonephritis accompanied by septic shock and acute kidney injury caused by hypermucoviscous Kpn infection that was successfully treated by intensive treatment. A 70-year-old woman with type 2 diabetes mellitus was diagnosed with emphysematous pyelonephritis, and string test-positive Kpn was detected in blood and urine cultures and percutaneous catheter drainage fluid from the renal pelvis. The patient was treated with intensive therapies including antibiotics, ventilator management, and continuous hemodiafiltration (CHDF) using AN69ST, which can absorb cytokines. During the course of treatment, the infection was complicated by pyogenic spondylitis, which was cured by antimicrobial therapy, and the patient was transferred to another hospital for rehabilitation on day 119 after admission. Hypermucoviscous Kpn infection often has a severe course, and it is important to initiate multidisciplinary treatment at an early stage, including rifampicin, which is expected to inhibit the viscosity of hypermucoviscous Kpn. In the current case, immediate CHDF using AN69ST was also considered a life-saving treatment because it improved both volume overload and neutrophil-activated hypercytokinemia.

Novel evidence on sepsis-inducing pathogens: from laboratory to bedside

Sepsis is a life-threatening condition and a significant cause of preventable morbidity and mortality globally. Among the leading causative agents of sepsis are bacterial pathogens Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, along with fungal pathogens of the Candida species. Here, we focus on evidence from human studies but also include in vitro and in vivo cellular and molecular evidence, exploring how bacterial and fungal pathogens are associated with bloodstream infection and sepsis. This review presents a narrative update on pathogen epidemiology, virulence factors, host factors of susceptibility, mechanisms of immunomodulation, current therapies, antibiotic resistance, and opportunities for diagnosis, prognosis, and therapeutics, through the perspective of bloodstream infection and sepsis. A list of curated novel host and pathogen factors, diagnostic and prognostic markers, and potential therapeutical targets to tackle sepsis from the research laboratory is presented. Further, we discuss the complex nature of sepsis depending on the sepsis-inducing pathogen and host susceptibility, the more common strains associated with severe pathology and how these aspects may impact in the management of the clinical presentation of sepsis.

Synergy of Plant Essential Oils in Antibiotic Therapy to Combat Klebsiella pneumoniae Infections

Increased antibiotic resistance presents a health problem worldwide. The World Health Organization published a list of pathogens considered a priority for designing new treatments. Klebsiella pneumoniae (Kp) is a top-priority microorganism, highlighting the strains that produce carbapenemases. Developing new efficient therapies or complementing existing treatments is a priority, and essential oils (EOs) provide an alternative. EOs could act as antibiotic adjuvants and enhance antibiotic activity. Employing standard methodologies, the antibacterial activity of the EOs and their synergic effect with antibiotics were detected. A string test was used to identify the impact of the EOs over the hypermucoviscosity phenotype presented by Kp strains, and Gas Chromatography-Mass Spectrometry analysis identified EOs and the composition of EOs. The potential of EOs for designing synergistic therapies with antibiotics to combat the infection of KPC diseases was demonstrated. In addition, the alteration of the hypermucoviscosity phenotype was shown as the principal mechanism of a synergic action between EOs and antibiotics. The differential composition of the EOs lets us identify some molecules that will be analyzed. Synergic activity of EOs and antibiotics can provide a solid platform for combating multiresistant pathogens that represent a severe health sector problem, such as Kp infections.

Phagocytosis is a primary determinant of pulmonary clearance of clinical Klebsiella pneumoniae isolates

Introduction

Klebsiella pneumoniae (Kp) is a common cause of hospital-acquired pneumonia. Although previous studies have suggested that evasion of phagocytic uptake is a virulence determinant of Kp, few studies have examined phagocytosis sensitivity in clinical Kp isolates.

Methods

We screened 19 clinical respiratory Kp isolates that were previously assessed for mucoviscosity for their sensitivity to macrophage phagocytic uptake, and evaluated phagocytosis as a functional correlate of in vivo Kp pathogenicity.

Results

The respiratory Kp isolates displayed heterogeneity in the susceptibility to macrophage phagocytic uptake, with 14 out of 19 Kp isolates displaying relative phagocytosis-sensitivity compared to the reference Kp strain ATCC 43816, and 5 out of 19 Kp isolates displaying relative phagocytosis-resistance. Intratracheal infection with the non-mucoviscous phagocytosis-sensitive isolate S17 resulted in a significantly lower bacterial burden compared to infection with the mucoviscous phagocytosis-resistant isolate W42. In addition, infection with S17 was associated with a reduced inflammatory response, including reduced bronchoalveolar lavage fluid (BAL) polymorphonuclear (PMN) cell count, and reduced BAL TNF, IL-1β, and IL-12p40 levels. Importantly, host control of infection with the phagocytosis-sensitive S17 isolate was impaired in alveolar macrophage (AM)-depleted mice, whereas AM-depletion had no significant impact on host defense against infection with the phagocytosis-resistant W42 isolate.

Conclusion

Altogether, these findings show that phagocytosis is a primary determinant of pulmonary clearance of clinical Kp isolates.

Antimicrobial Resistance Pattern, Pathogenicity and Molecular Properties of Hypervirulent Klebsiella pneumonia (hvKp) among Hospital-Acquired Infections in the Intensive Care Unit (ICU)

Hypervirulent Klebsiella pneumoniae (hvKp) is a new emerging variant of K. pneumoniae that is increasingly reported worldwide. The variant hvKp is known to cause severe invasive community-acquired infections such as metastatic meningitis, pyogenic liver abscesses (PLA) and endophthalmitis, but its role in hospital-acquired infections (HAIs) is little known. The aim of this study was to evaluate the prevalence of hvKp among hospital-acquired (HA) K. pneumoniae infections in the intensive care unit (ICU) and to compare between hvKp and classical K. pneumoniae (cKP) regarding antimicrobial resistance pattern, virulence and molecular characteristics. The study was cross-sectional and included 120 ICU patients suffering from HA K. pneumoniae infections between January and September 2022. K. pneumoniae isolates were subjected to antimicrobial susceptibility testing and detection of extended-spectrum-β-lactamase (ESBL) production by the Phoenix 100 automated microbiology system, string test, biofilm formation, serum resistance assay, and detection of virulence-associated genes (rmpA, rmpA2, magA, iucA) and capsular serotype-specific genes (K1, K2, K5, K20, K57) by polymerase chain reaction (PCR). Of 120 K. pneumoniae isolates, 19 (15.8%) were hvKp. The hypermucoviscous phenotype was more significantly detected in the hvKp group than in the cKP group (100% vs. 7.9%, p ≤ 0.001). The rate of resistance to different antimicrobial agents was significantly higher in the cKP group than that in the hvKp group. Fifty-three strains were identified as ESBL-producing strains, which was more frequent in the cKP group than in the hvKp group (48/101 [47.5%] vs. 5/19 [26.3%], respectively, p ≤ 0.001). The hvKP isolates were highly associated with moderate and strong biofilm formation than cKP isolates (p = 0.018 and p = 0.043 respectively). Moreover, the hvKP isolates were highly associated with intermediate sensitivity and re sistance to serum in the serum resistance assay (p = 0.043 and p = 0.016 respectively). K1, K2, rmpA, rmpA2, magA and iucA genes were significantly associated with hvKp (p ≤ 0.001, 0.004, <0.001, <0.001, 0.037 and <0.001, respectively). However, K5, K20 and K57 were not associated with hvKp. The hvKp strains have emerged as a new threat to ICU patients because of their ability to cause more severe and life-threatening infections than cKP. The string test alone as a laboratory test for screening of hvKp has become insufficient. Recently, hvKp was defined as hypermucoviscous- and aerobactin-positive. It is important to improve the awareness towards the diagnosis and management of hvKp infections.

Determination of extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolated from horses with respiratory manifestation

Background and Aim:

The World Health Organization considers multidrug-resistant (MDR) Klebsiella pneumoniae a major global threat. Horses harbor commensal isolates of this bacterial species and potentially serve as reservoirs for human MDR bacteria. This study investigated antimicrobial resistance in horses caused by extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae.

Materials and Methods:

One hundred fifty-nine nasal swab samples were collected from horses with respiratory distress not treated with cefotaxime and erythromycin. Biochemical and serological identification was performed on all samples. Polymerase chain reaction (PCR) was used to detect 16S-23S ITS, mucoviscosity-associated gene (magA), uridine diphosphate galacturonate 4-epimerase gene (uge), and iron uptake system gene (kfu), bla_TEM, bla_SHV, and bla_CTX genes. Sequence analysis and phylogenetic relatedness of randomly selected K. pneumoniae isolates carrying the bla_TEM gene were performed.

Results:

Ten isolates of Klebsiella spp. were obtained from 159 samples, with an incidence of 6.28% (10 of 159). Based on biochemical and serological identification, K. pneumoniae was detected in 4.4% (7 of 159) of the samples. Using PCR, all tested K. pneumoniae isolates (n=7) carried the 16S-23S ITS gene. By contrast, no isolates carried magA, uge, and kfu genes. The bla_TEM gene was detected in all test isolates. Moreover, all isolates did not harbor the bla_SHV or bla_CTX gene. Sequence analysis and phylogenetic relatedness reported that the maximum likelihood unrooted tree generated indicated the clustering of the test isolate with the other Gram-negative isolate bla_TEM. Finally, the sequence distance of the bla_TEM gene of the test isolate (generated by Lasergene) showed an identity range of 98.4-100% with the bla_TEM gene of the different test isolates.

Conclusion:

The misuse of antimicrobials and insufficient veterinary services might help generate a population of ESBL-producing K. pneumoniae in equines and humans, representing a public health risk.

Virulence Factors in Hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKP) has spread globally since first described in the Asian Pacific Rim. It is an invasive variant that differs from the classical K. pneumoniae (cKP), with hypermucoviscosity and hypervirulence, causing community-acquired infections, including pyogenic liver abscess, pneumonia, meningitis, and endophthalmitis. It utilizes a battery of virulence factors for survival and pathogenesis, such as capsule, siderophores, lipopolysaccharide, fimbriae, outer membrane proteins, and type 6 secretion system, of which the former two are dominant. This review summarizes these hvKP-associated virulence factors in order to understand its molecular pathogenesis and shed light on new strategies to improve the prevention, diagnosis, and treatment of hvKP-causing infection.

Clinical and computed tomography features of extended-spectrum β-lactamase-producing Klebsiella pneumoniae liver abscess

Background

Klebsiella pneumoniae (KP) is the primary pathogen associated with pyogenic liver abscesses (PLAs). Moreover, there has been an increase in the proportion of extended-spectrum beta-lactamase (ESBL)-producing KP. However, the clinical and computed tomography (CT) features of liver abscesses caused by ESBL-producing KP have not been separately described. We aimed to compare the clinical and CT features present in patients with ESBL-producing and non-ESBL-producing KP as well as to determine the risk factors for ESBL-producing KP liver abscesses (KPLAs).

Methods

We performed a retrospective analysis of data obtained from the medical records of patients with a first episode of KPLA admitted to Shengjing Hospital of China Medical University between May 2015 and May 2019. We compared the clinical and CT features between patients with ESBL-producing and non-ESBL-producing KPLA.

Results

We enrolled 100 patients with KPLA (14 and 86 in the ESBL-producing and non-ESBL-producing groups, respectively). There was no significant between-group difference in the proportion of patients with comorbid diabetes (71.43% vs. 66.2%, p = 0.086). The ESBL-producing KPLA group had a greater proportion of patients with a history of biliary disease (78.57% vs. 26.74%, p < 0.001) and gastrointestinal malignancy (50% vs. 6.98%, p < 0.001). Multivariate regression analysis showed that a history of biliary disease was an independent risk factor for ESBL-producing KPLA. Compared with the non-ESBL-producing KPLA group, the ESBL-producing KPLA group had a significantly higher intensive care unit (ICU) admission rate (28.57% vs. 2.33%, p < 0.001). All ESBL-producing KP isolates were susceptible to carbapenems and amikacin. Only the presence of multiloculation on CT was found to be significantly different between the groups (50% vs. 82.56%, p = 0.012).

Conclusions

The presence of biliary disease was an independent risk factor for ESBL-producing KPLA. Patients with ESBL-producing KPLA had a higher ICU admission rate, with only half of patients having evidence of multiloculation on CT.

Hypervirulent Klebsiella pneumoniae - clinical and molecular perspectives

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a concerning global pathogen. hvKp is more virulent than classical K. pneumoniae (cKp) and capable of causing community-acquired infections, often in healthy individuals. hvKp is carried in the gastrointestinal tract, which contributes to its spread in the community and healthcare settings. First recognized in Asia, hvKp arose as a leading cause of pyogenic liver abscesses. In the decades since, hvKp has spread globally and causes a variety of infections. In addition to liver abscesses, hvKp is distinct from cKp in its ability to metastasize to distant sites, including most commonly the eye, lung and central nervous system (CNS). hvKp has also been implicated in primary extrahepatic infections including bacteremia, pneumonia and soft tissue infections. The genetic determinants of hypervirulence are often found on large virulence plasmids as well as chromosomal mobile genetic elements which can be used as biomarkers to distinguish hvKp from cKp clinical isolates. These distinct virulence determinants of hvKp include up to four siderophore systems for iron acquisition, increased capsule production, K1 and K2 capsule types, and the colibactin toxin. Additionally, hvKp strains demonstrate hypermucoviscosity, a phenotypic description of hvKp in laboratory conditions that has become a distinguishing feature of many hypervirulent isolates. Alarmingly, multidrug-resistant hypervirulent strains have emerged, creating a new challenge in combating this already dangerous pathogen.

Virulence Factors, Capsular Serotypes and Antimicrobial Resistance of Hypervirulent Klebsiella pneumoniae and Classical Klebsiella pneumoniae in Southeast Iran

BACKGROUND

The present study was conducted to investigate the distribution of virulence factors, capsular serotypes and antibiotic resistance properties of classical Klebsiella pneumoniae (cKP) and hypermucoviscous/hypervirulent Klebsiella pneumoniae (hvKP) isolated from different clinical specimens in Kerman, south-east of Iran.

MATERIALS AND METHODS

A total of 146 K. pneumoniae isolates were obtained from different clinical specimens. HvKP isolates were identified using the string test. Genes of capsular serotypes K1, K2, K5, K20, K54 and K57 and virulence-associated genes, rmpA, kfu, fimH, mrkD, allS, iutA, magA, entB and ybtS were evaluated by PCR. Antimicrobial susceptibility was also determined using the disc diffusion method.

RESULTS

Out of 146 K. pneumoniae isolates, 22 (15.1 %) were hvKP. More than half of the hvKP isolates, 13 (59.1%), belonged to non-K1, K2, K5, K20, K54, K57 serotypes. Out of 22 hvKP isolates, 3 and 3 had K1 and K2 serotypes respectively. Among all isolates, entB 140 (95.9%) and mrkD 138 (94.5%) were the most common virulence genes. RmpA, iutA and kfu were associated with hvKP isolates (P-value <0.05). However, no significant difference was found in fimH, allS, mrkD, entB and ybtS genes between hvKP and cKP strains. HvKP exhibited significantly lower resistance rates to all antimicrobial agents than cKP, except to trimethoprim-sulphamethoxazole and ampicillin (P-value <0.05).

CONCLUSION

The frequency of hvKP was low, but overall, the prevalence of virulence-related genes was higher in hvKP than cKP. HvKP was not related to specific serotypes. Furthermore, hvKP isolates were more susceptible to antimicrobial agents compared to cKP isolates.

Clinical characteristics of bacteremia caused by hypermucoviscous Klebsiella pneumoniae at a tertiary hospital

This study aimed to assess the predictive factors of bacteremia due to hypermucoviscous Klebsiella pneumoniae (hvKP), as well as the mortality. The medical records of 114 patients with K. pneumoniae bacteremia who were divided into the hvKP (n = 24) and non-hvKP (n = 90) groups and were retrospectively reviewed. The male-to-female ratio, age, and underlying disease did not differ between the 2 groups. Mortality was higher among patients in the hvKP bacteremia group than in the non-hvKP bacteremia group (29.2% vs 6.7%). Multivariate analysis showed that the independent predictors associated with hvKP bacteremia were abscess (P = 0.01) and no antibiotic exposure (P = 0.02); thus, early assessment of these conditions is important. For patients with a history of abscess and no antibiotic exposure, it is necessary to administer treatment while keeping the risk of hvKP in mind.

Hypervirulent Klebsiella pneumoniae as a hospital-acquired pathogen in the intensive care unit in Mansoura, Egypt

Introduction

Hypervirulent Klebsiella pneumoniae (hvKP) are variants of K. pneumoniae that come up worldwide. hvKP is known in community-acquired infections but little is known about its role in hospital-acquired (HA) infections. The aim of this study was to evaluate the frequency of hvKP among HA K. pneumoniae infections in the intensive care unit (ICU) and to compare virulence and antibiotic susceptibility between hvKP and classical K. pneumoniae (cKP).

Methods

String test, biofilm formation, serum bactericidal assay, capsular polysaccharide genes (K1, K2, K5, K20, K54, K57), virulence genes: rmpA, rmpA2, iucA, iroB and antimicrobial susceptibility were assessed in HA K. pneumoniae strains isolated from the ICU in Mansoura, Egypt.

Results

Probable hvKP represented 4 out of 65 (6.2%) K. pneumoniae. K1 and K2 genes were present in 2 and 1 isolate respectively in probable hvKP. rmpA genes were significantly associated with hvKP; at the same time biofilm production and serum resistance were not significantly associated with the hypervirulent group. There was no significant difference between hvKP and cKP strains in terms of resistance pattern.

Conclusion

hvKP in critically ill patients from the ICU may form a new threat especially in the presence of antibiotic resistance. Although the validity of the string test in detecting metastatic Klebsiella is questionable, it is a simple and easy test that can be done in any laboratory indicating the presence of this organism. Serotypes and genomic background may provide helpful and confirmatory tools to diagnose hvKP.

Bloodstream infections caused by Klebsiella pneumoniae: prevalence of blaKPC, virulence factors and their impacts on clinical outcome

Background

Klebsiella pneumoniae bloodstream infections (BSIs) occur with significant prevalence and high mortality worldwide. Antimicrobial resistance and virulence are two main factors participating in the pathogenicity of K. pneumoniae. Here we investigated the prevalence of bla_KPC and virulence factors in K. pneumoniae isolated from patients with BSIs and their association with clinical outcome.

Methods

The clinical data of 285 K. pneumoniae BSI cases diagnosed from January 2013 to December 2015 in a Chinese university hospital were retrospectively evaluated. The “string test” was performed to identify hypermucoviscous K. pneumoniae (HMKP). bla_KPC, rmpA, magA and serotype-specific genes were detected by PCR amplification. Finally, a Cox proportional hazards model was employed to determine the predictors of 14-day mortality.

Results

Of these isolates, the prevalence of bla_KPC and rmpA were 33.3% (95/285) and 31.6% (90/285) respectively. 69 isolates (24.2%, 69/285) were HMKP. rmpA was strongly associated with HM phenotype. The KPC-producing KP and HMKP were almost non-overlapping and only three HMKP isolates harbored bla_KPC. K1 (28, 40.6%) and K2 (22, 31.9%) were the most common serotypes in HMKP. 44.9% of HMKP BSIs had origin of biliary tract infection or liver abscess. The 14-day mortality was 100% in bla_KPC⁺/HM⁺ subgroup (3/3), followed by bla_KPC⁺/HM⁻ (39/92, 42.4%), bla_KPC⁻/HM⁺ (5/66, 7.6%) and bla_KPC⁻/HM⁻ (7/124, 5.6%). The 14-day cumulative survival was significantly different between bla_KPC⁺ and bla_KPC⁻ subgroup (Log-rank p < 0.001) but almost equal between bla_KPC⁻/HM⁺ and bla_KPC⁻/HM⁻ subgroup (Log-rank p = 0.578) under the condition of comparable illness severity between bla_KPC⁻/HM⁺ and bla_KPC⁻/HM⁻ subgroup. Independent risk factors for 14-day mortality were Pitt bacteremia score (HR 1.24, CI 95% 1.13–1.36, p < 0.001), Charlson comorbidity index (HR 1.24, CI 95% 1.09–1.41, p = 0.001), septic shock (HR 2.61, CI 95% 1.28–5.35, p = 0.009) and bla_KPC (HR 2.20, CI 95% 1.06–4.54, p = 0.034).

Conclusions

Most of HMKP were antibiotic-susceptible and people infected received appropriate antimicrobial therapy, which may explain the favorable outcome of HMKP BSIs. The KPC-producing HMKP BSIs were scarce but life-threatening. bla_KPC was valuable in predicting 14-day mortality.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3263-x) contains supplementary material, which is available to authorized users.

Clinical and microbiological characteristics and occurrence of Klebsiella pneumoniae infection in Japan

Purpose

Klebsiella pneumoniae is a pathogen that causes pneumonia and urinary tract infection. Hypervirulent K. pneumoniae strains often show hypermucoviscosity, are of the K1 or K2 serotype, and harbor the rmpA and magA genes. However, the differences in the prevalence of K. pneumoniae with these hypervirulent characteristics between the infection and colonization status are not well understood. Therefore, in this study, we compared the clinical and microbiological characteristics of K. pneumoniae isolated from urine or sputum samples of cases of infection and colonization.

Patients and methods

This retrospective study was conducted at a tertiary care teaching hospital in Tokyo, Japan. Patients whose sputum or urine tested positive for the presence of K. pneumoniae isolates were randomly included in the study. Clinical and microbiological data were collected from medical records.

Results

Of the 130 cases investigated, 68 and 62 cases showed the presence of K. pneumoniae in the sputum and urine, respectively. There were 49 infection cases, including 21 in the sputum group and 28 in the urine group. The infections were not accompanied by liver abscess. Of the 130 K. pneumoniae isolates, 25 (19.2%) showed capsular serotype K1 or K2, whereas 33 (25.4%) showed hypermucoviscosity. The prevalence of virulence genes magA, allS, rmpA, mrkD, uge, kfu-BC, and wabG was 10% (all in K1), 13.1%, 16.9%, 85.4%, 79.2%, 36.9%, and 91.5%, respectively. In both the sputum and urine groups, there was no difference in the characteristics of patients with infection and those with colonization. Analysis of microbiological characteristics revealed that only rmpA was significantly more frequent in the infection cases than in the colonization/asymptomatic cases in both the sputum and urine groups.

Conclusion

The rmpA-positive K. pneumoniae isolates were dominant in the infection cases compared with those in the colonization/asymptomatic cases, suggesting that rmpA may play a crucial role in the development of urinary tract infection and pneumonia.

Risk factors and clinical outcomes of hypervirulent Klebsiella pneumoniae induced bloodstream infections

The prevalence of hypervirulent Klebsiella pneumoniae (hvKP) is high in China, but clinical characteristics and outcomes of hvKP induced bloodstream infections (BSIs) are not clear. The purpose of the present study was to determine the risk factors and clinical outcomes of hvKP-BSIs in populations admitted in a teaching hospital of Nanjing, China. The genetic characteristics and antibiotic resistance patterns of the hvKP strains were further analyzed. A retrospective study was conducted in 143 patients with K. pneumoniae BSIs at Jinling Hospital in China from September 2015 to December 2016. A positive polymerase chain reaction (PCR) amplification of the plasmid-borne rmpA (p-rmpA) and aerobactin (iucA) was identified as hvKP. Overall, 24.5% (35/143) of K. pneumoniae isolates were hvKP. Multivariate analysis implicated diabetes mellitus (OR = 3.356) and community-acquired BSIs (OR = 4.898) as independent risk factors for hvKP-BSIs. The 30-day mortality rate of the hvKP-BSIs group was 37.1% (13/35) compared with 40.7% (44/108) in the cKP-BSIs control group (P = 0.706). The KPC-producing isolates (OR = 2.851), underlying disease with gastrointestinal fistula (OR = 3.054), APACHE II score ≥ 15 (OR = 6.694) and Pitt bacteremia score ≥ 2 (OR = 6.232) at infection onset were independent predictors for 30-day mortality of K. pneumoniae bacteremia patients. A high percentage (57.1%, 20/35) of KPC-producing isolates was observed among hvKP strains and ST11 was dominant in hvKP strains (17/35, 48.6%). KPC-producing hvKP is emerging, indicating the importance of epidemiologic surveillance and clinical awareness of this pathogen.

Risk factors of mortality in bloodstream infections caused by Klebsiella pneumonia: A single-center retrospective study in China

The prevalence of Klebsiella pneumonia bloodstream infections (KP-BSIs) is increasing worldwide. Few study reports focus on the KP-BSIs published in Mainland China over the previous years. This study aimed to describe the risk factors of mortality from KP-BSIs.A retrospective study was conducted in a teaching hospital in Shanghai, China, for a period of 4 years. Risk factors related to the patient mortality were analyzed using the binary logistic regression model.Of 104 patients with KP-BSIs, the overall 30-day mortality rate was 25%. The logistic regression analysis revealed that thrombocytopenia (TB) (odds ratio [OR]: 1.007, 95% confidence interval [CI]: 1.002-1.013), pancreaticobiliary tract (PBT) (OR: 4.059, 95% CI: 1.398-11.78), and intra-abdominal infection (OR: 6.816, 95% CI: 1.806-25.716) were powerful risk factors leading to the mortality associated with KP-BSIs. Although prior antibiotic exposure, inappropriate empirical antibiotics, and inappropriate definitive antibiotics were not associated with mortality, multidrug-resistant (MDR) of KP-BSIs in the present study was high in both survivors and nonsurvivors (67.9% and 88.5%, respectively).TB, PBT, and intra-abdominal infection caused significant mortality rates increase in KP-BSIs during the study period.

Hypervirulence and hypermucoviscosity: Two different but complementary Klebsiella spp. phenotypes?

Since the hypermucoviscous variants of Klebsiella pneumoniae were first reported, many cases of primary liver abscesses and other invasive infections caused by this pathogen have been described worldwide. Hypermucoviscosity is a phenotypic feature characterized by the formation of a viscous filament ≥5 mm when a bacterial colony is stretched by a bacteriological loop; this is the so-called positive string test. Hypermucoviscosity appears to be associated with this unusual and aggressive type of infection, and therefore, the causal strains are considered hypervirulent. Since these first reports, the terms hypermucoviscosity and hypervirulence have often been used synonymously. However, new evidence has suggested that hypermucoviscosity and hypervirulence are 2 different phenotypes that should not be used synonymously. Moreover, it is important to establish that a negative string test is insufficient in determining whether a strain is or is not hypervirulent. On the other hand, hypervirulence- and hypermucoviscosity-associated genes must be identified, considering that these phenotypes correspond to 2 different phenomena, regardless of whether they can act in synergy under certain circumstances. Therefore, it is essential to quickly identify the genetic determinants behind the hypervirulent phenotype to develop effective methodologies that can diagnose in a prompt and effective way these hypervirulent variants of K. pneumoniae.

Enterococcus hirae Bacteremia Associated with Acute Pancreatitis and Septic Shock

Infection with Enterococcus hirae has rarely been reported in humans but is not uncommon in mammals and birds. We describe a case of Enterococcus hirae bacteremia associated with acute pancreatitis, acute cholecystitis, and septic shock responsive to antibiotic therapy and supportive critical care management. Unique aspects of this case of Enterococcus hirae bacteremia are its association with acute pancreatitis and its geographical origin. To our knowledge, this is the first report of Enterococcus hirae bacteremia occurring in a patient in the United States. Although human infection with this organism appears to be rare, all cases reported to date describe bacteremia associated with severe and life-threatening illness. Thus, physicians need to be cognizant of the clinical significance of this heretofore little recognized pathogen.