Recurrent Klebsiella pneumoniae mycotic aneurysm in a diabetic patient and emergence of an extended-spectrum beta-lactamase (CTX-M-24)-containing Klebsiella pneumoniae strain after prolonged treatment with first-generation cephalosporins for mycotic aneurysm

Clinical and microbiologic characteristics of adult patients with recurrent bacteraemia caused by extended-spectrum β-lactamase-producing Escherichia coli or Klebsiella pneumoniae

The characteristics of patients with recurrent bacteraemia caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli or Klebsiella pneumoniae (EK) are rarely described. Flomoxef belongs to the cephamycins group and demonstrates in vitro activity against ESBL-producing organisms. Whether flomoxef may be used for the treatment of such infections remains controversial. This retrospective case-control study enrolled adult patients who had bacteraemia caused by ESBL-EK during 2005-2011. Case patients were those who had more than one episode of ESBL-EK bacteraemia. Controls were those who were matched for age and interval time of blood sampling and had only one episode of ESBL-EK bacteraemia with subsequent bacteraemia episodes caused by other non-ESBL-EK bacteria. Pulsed-field gel electrophoresis and microbiologic profiles of the initial and subsequent ESBL-EK isolates were analysed. During the study period, 424 patients were found to have at least one positive blood culture after the first ESBL-EK bacteraemia episode, and 67 (15.8%) had a second episode of ESBL-EK bacteraemia. Bacteraemia resulting from vascular catheter-related infection (odds ratio, 3.24; 95% confidence interval, 1.31-8.05), and definitive therapy with flomoxef (odds ratio, 2.99; 95% confidence interval, 1.10-8.15) were both independent risk factors for the recurrence. Among the 56 patients with available ESBL-EK isolates for analysis, 38 (67.8%) were infected by genetically similar strains. In three of these 38 recurrent ESBL-EK bacteraemia cases caused by an identical strain, the minimum inhibitory concentrations of carbapenem for the subsequent K. pneumoniae isolates were fourfold or higher than the initial isolates. Recurrent bacteraemia was not uncommon in our patients with ESBL-EK bacteraemia, and most of the episodes were caused by identical strains.

A Fatal Case of Klebsiella pneumoniae Mycotic Aneurysm

Mycotic aneurysm is a serious clinical condition with significant morbidity and mortality. Staphylococcus aureus and Salmonella species are the most common causative pathogens. Klebsiella pneumoniae was rarely reported as a possible pathogen causing mycotic aneurysm; therefore, we describe a K. pneumoniae-related fatal bacteremia mycotic aneurysm in a patient in spite of appropriate antimicrobial agents and surgical management.

Spread of ISCR1 elements containing blaDHA-₁ and multiple antimicrobial resistance genes leading to increase of flomoxef resistance in extended-spectrum-beta-lactamase-producing Klebsiella pneumoniae

Increasing resistance to quinolones, aminoglycosides, and/or cephamycins in extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae exacerbates the already limited antibiotic treatment options for infections due to these microbes. In this study, the presence of resistance determinants for these antimicrobial agents was examined by PCR among ESBL-producing Klebsiella pneumoniae (ESBL-KP) isolates that caused bacteremia. Pulsed-field gel electrophoresis was used to differentiate the clonal relationship among the isolates studied. Transferability and the location of the resistance genes were analyzed by conjugation experiments, followed by DNA-DNA hybridization. Among the 94 ESBL-KP isolates studied, 20 isolates of flomoxef-resistant ESBL-KP were identified. They all carried a DHA-1 gene and were genetically diverse. CTX-M genes were found in 18 of the isolates. Among these DHA-1/CTX-M-producing K. pneumoniae isolates, ISCR1 was detected in 13 (72%) isolates, qnr genes (1 qnrA and 17 qnrB genes) were detected in 18 (100%), aac(6')-Ib-cr was detected in 11 (61%), and 16S rRNA methylase (all armA genes) was detected in 14 (78%). Four transconjugants were available for further analysis, and qnrB4, aac(6')-Ib-cr, armA, and bla(DHA-1) were all identified on these self-transferable bla(CTX-M)-carrying plasmids. The genetic environments of ISCR1 associated with armA, bla(DHA-1), and qnrB4 genes in the four transconjugants were identical. Replicon-type analysis revealed a FIIA plasmid among the four self-transferable plasmids, although the other three were nontypeable. The cotransfer of multiple resistance genes with the ISCR1 element-carrying plasmids has a clinical impact and warrants close monitoring and further study.

Microbiologic and clinical implications of bacteremia due to extended-spectrum-beta-lactamase-producing Klebsiella pneumoniae with or without plasmid-mediated AmpC beta-lactamase DHA-1

Bacteremias caused by Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL-KP; n = 52) and producing both ESBL and AmpC-type DHA-1 beta-lactamase (ESBL-PMABL-KP; n = 20) were analyzed. Higher MIC(50)s and MIC(90)s for carbapenems, ciprofloxacin, and piperacillin-tazobactam were observed with ESBL-PMABL-KP than with ESBL-KP. Patients with oxyimino-β-lactam exposure and high modified Pitt bacteremia scores (HMPBSs) were at higher risk, while those with piperacillin-tazobactam and aminoglycoside exposure were at lower risk for ESBL-KP bacteremia. Patients with fluoroquinolone exposure, diabetes mellitus, and HMPBS were at higher risk, while those with aminoglycoside exposure were at lower risk, for ESBL-PMABL-KP bacteremia.

Termination of a 4-month serial Klebsiella pneumoniae septicemia in a diabetic woman after aneurysmectomy in conjunction with antimicrobial therapy

A diabetic woman suffered from deep neck infection, endophthalmitis, urinary tract infection, and mycotic aneurysm associated Klebsiella pneumoniae bacteremia for 4 months. Aneurysmectomy and antibiotic therapy terminated recurrent K pneumoniae sepsis suggestive of removal of the pathogen niche in an artery, which served as the root of serial infections. The DNA fingerprints of K pneumoniae isolates indicated that the same strain K pneumoniae caused all the infection episodes. The case is reported and its clinical implications are discussed.

Mycotic aneurysm caused by gas-forming serotype K5 Klebsiella pneumoniae

We describe the first documented case of mycotic aneurysm caused by gas-forming serotype K5, and rmpA and iuc positive Klebsiella pneumonia with a hypermucoviscosity phenotype in a diabetic patient. The patient received ceftriaxone for one month and underwent aorto-bi-iliac grafting and inferior mesenteric artery reimplantation and recovered well.

Prevalence of extended-spectrum beta-lactamases in Proteus mirabilis in a Taiwanese university hospital, 1999 to 2005: identification of a novel CTX-M enzyme (CTX-M-66)

A total of 1574 nonduplicate Proteus mirabilis isolates collected at a Taiwanese hospital during 1999 to 2005 were analyzed for production of extended-spectrum beta-lactamases (ESBLs). Forty-four ESBL-producing isolates including 22 CTX-M-14, 18 CTX-M-3, 2 CTX-M-24, and 2 CTX-M-66 producers were detected, and the proportion of ESBL producers increased from 0.7% in 1999 to approximately 6% after 2002. CTX-M-66 is a novel variant of CTX-M ESBLs that differs from CTX-M-3 by a Ser to Asn change at amino acid position 23. Coresistances to aminoglycosides and ciprofloxacin were very common in the CTX-M-3 producers. The presence of ArmA-type or RmtB-type 16S rRNA methylase that confers high-level aminoglycoside resistance was detected in 12 CTX-M-3 producers and 4 CTX-M-14 producers. Twenty-four clones including an endemic CTX-M-14-producing clone were observed among the 44 ESBL producers by pulsed-field gel electrophoresis, suggesting that both horizontal transfer and clonal spread contributed to the increased prevalence of bla(CTX-M) in P. mirabilis.

Non-aneurysmal infectious aortitis: a case report

Infectious aortitis is a rare clinical entity that is most often associated with an abdominal aortic aneurysm. There have been very few documented cases of aortitis in the setting of a normal-sized caliber aorta. We present a 67-year-old patient who presented to our Emergency Department with a history of recent fevers, fatigue, and abdominal pain. Based on an abdominal computed tomography scan, the patient was initially thought to have ruptured an abdominal aortic aneurysm of infectious etiology with extension into the left psoas muscle. Explorative laparotomy, however, revealed an infected abdominal aorta secondary to a retroperitoneal abscess with no evidence of aneurysm or pseudoaneurysm. The pathophysiology of the disease suggests that infectious aortitis and mycotic aneurysm represent extremes along a spectrum of the same disease. Establishing a diagnosis of aortic infection before the formation of an aneurysm or rupture is very difficult, but essential in preventing the devastating complications.