Matthaios Papadimitriou-Olivgeris

Risk factors for KPC-producing Klebsiella pneumoniae enteric colonization upon ICU admission

OBJECTIVES To identify risk factors for KPC-producing Klebsiella pneumoniae (KPC-Kp) enteric colonization at intensive care unit (ICU) admission. Recently, the emergence and spread of KPC-producing Enterobacteriaceae in healthcare facilities has become an important issue. Understanding the extent of the reservoir in ICUs may be important for targeted intervention. METHODS A prospective observational study of all patients (n = 405) admitted to an ICU was conducted during a 22 month period. Rectal samples were taken from each patient within 12-48 h of admission and were inoculated in selective chromogenic agar. K. pneumoniae isolates were characterized by standard methodology. Antibiotic susceptibility testing (agar disc diffusion method), MIC determination (Etest), identification of carbapenemase-producing isolates (Hodge test) and determination of KPC production (boronic acid-imipenem disc test) were performed. The presence of the bla(KPC) gene was confirmed by PCR. Epidemiological data were collected from the ICU computerized database and patient chart reviews. RESULTS Upon ICU admission, 52/405 (12.8%) patients were colonized with KPC-Kp that was associated with the following risk factors: previous ICU stay (OR 12.5; 95% CI 1.8-86.8), chronic obstructive pulmonary disease (OR 6.3; 95% CI 1.2-31.9), duration of previous hospitalization (OR 1.3; 95% CI 1.1-1.4), previous use of carbapenems (OR 5.2; 95% CI 1.0-26.2) and previous use of β-lactams/β-lactamase inhibitors (OR 6.7; 95% CI 1.4-32.9). For patients previously hospitalized on peripheral wards the following risk factors were identified: duration of hospitalization prior to ICU admission (OR 1.1; 95% CI 1.1-1.3), number of comorbidities (OR 1.9; 95% CI 1.1-3.5) and number of antimicrobials administered (OR 2.1; 95% CI 1.3-3.3). CONCLUSIONS The high prevalence of KPC-Kp enteric carriage in ICU patients at admission dictates the importance of implementation of infection control measures and strict antibiotic policies prior to ICU transfer.

KPC-producing Klebsiella pneumoniae enteric colonization acquired during intensive care unit stay: the significance of risk factors for its development and its impact on mortality

A prospective observational study of 226 intensive care unit (ICU) patients was conducted during a 25-month period. Rectal samples were taken at day 1, 4, and 7 and, afterwards, once weekly. Klebsiella pneumoniae was identified using standard techniques, whereas the presence of bla(KPC) gene was confirmed by PCR. During ICU stay, 72.6% of the patients were colonized with Klebsiella pneumoniae carbapenemases (KPC)-producing K. pneumoniae (KPC-Kp). Male gender, prior bed occupants, and patients in nearby beds colonized with KPC-Kp, tracheotomy, number of invasive catheters inserted, and number of antibiotics administered were the major risk factors for KPC-Kp colonization. ICU mortality (35.4%) was significantly related to Simplified Acute Physiology II score and respiratory insufficiency upon admission, cortisone administration, aminoglycoside administration, confirmed KPC-Kp infection, and severe sepsis or septic shock. The high prevalence of KPC-Kp enteric carriage in ICU patients and the significant mortality associated with KPC-Kp infection dictate the importance of early identification and isolation of such carriers.

Risk factors for infection and predictors of mortality among patients with KPC-producing Klebsiella pneumoniae bloodstream infections in the intensive care unit

Abstract Background: Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp) infections in intensive care units (ICUs) are associated with increased mortality. We aimed to determine risk factors for infection and predictors of 30-day mortality in ICU patients with KPC-Kp bloodstream infections (BSI). Methods: During a 26-month period, patients (n = 273) who stayed more than 6 days in the ICU of the University Hospital of Patras, Greece, were divided into 2 groups, those who developed KPC-Kp BSI and those who did not. K. pneumoniae was identified by Vitek 2 technology. Antibiotic susceptibility testing was performed by agar disk diffusion method. Minimum inhibitory concentrations were determined by Etest. The presence of the blaKPC gene was confirmed by PCR. Molecular typing was performed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Epidemiological data were collected by patient chart review. Results: Five patients had bacteraemia upon admission, while in 48 (17.6%) the BSI developed after 6 days of hospitalization. Risk factors for KPC-Kp BSI in the latter group were the administration of aminoglycosides, number of invasive catheters inserted after the third day, and tracheostomy. The 30-day mortality was 43.4% (23/53 patients). Multivariate analysis revealed that age, SAPS II score at onset of BSI, resistance to colistin, gentamicin, or tigecycline, and septic shock were independently associated with mortality. Treatment with at least 2 appropriate antibiotics was identified as a predictor of a good prognosis. Conclusions: Many risk factors are involved in KPC-Kp BSI among ICU patients. The high mortality in patients with KPC-KP BSI in the ICU requires the implementation of appropriate infection control measures.

A ten-year surveillance study of carbapenemase-producing Klebsiella pneumoniae in a tertiary care Greek university hospital: predominance of KPC- over VIM- or NDM-producing isolates.

Resistance patterns and carbapenemase gene presence among Klebsiella pneumoniae isolates from the University General Hospital of Patras, Greece during a ten-year period were analysed under a surveillance programme for multi-drug-resistant bacteria. From 2005 to 2014, K. pneumoniae isolates from clinically significant specimens were identified by the Vitek 2 Advanced Expert System. Antibiotic susceptibility testing was performed by the agar disc diffusion method and Etest. The strains were tested for the presence of blaVIM, blaIMP, blaKPC, blaNDM and blaOXA-48 genes by PCR. PFGE of chromosomal Xbal DNA digests was performed. A total of 3449 K. pneumoniae isolates were recovered during the last decade. Among them, 1668 (48 %) were carbapenemase-producing: 1333 (80%) K. pneumoniae carbapenemase (KPC)-, 286 (17%) Verona imipenemase (VIM), 45 (3%) KPC- and VIM-, and four New Delhi metallo-beta-lactamase (NDM)-producing. Their resistance rates to gentamicin, colistin and tigecycline were 41%, 23% and 16%, respectively. VIM-producing K. pneumoniae were isolated in 2005 and since 2008 have been endemic. KPC-producing K. pneumoniae (KPC-Kp) isolates were introduced in 2008 and until now represent the predominant carbapenemase-producing K. pneumoniae in our institution. PFGE of 97 KPC-Kp strains identified three types: A, 84 (87%); B, 11 (11%); and E, two (2%). Eleven co-producing KPC and VIM K. pneumoniae isolates belonged to PFGE B. The four NDM-positives were classified to type F. The number of K. pneumoniae bacteraemias increased during the study period, which may be solely attributed to the increase of carbapenemase-producing isolates. The threat of carbapenemase-producing K. pneumoniae emphasizes the urgent need for implementation of infection control measures and budgetary allocations to infection control.

Association of KPC-producing Klebsiella pneumoniae colonization or infection with Candida isolation and selection of non-albicans species

Clinical specimens from 565 patients hospitalized in 2 intensive care units (ICUs A and B) during a 28-month period were cultured on appropriate media for isolation of Candida. Forty-nine (9%) patients had at least a Candida spp.-positive sample. Candida albicans was the predominant species isolated from 26 (53%) patients. Seventeen patients (3%) developed candidemia. Multivariate analysis showed that obesity, female gender, hospitalization during summer months, admission at ICU B, parenteral nutrition, administration of metronidazole, transplantation, and KPC-producing Klebsiella pneumoniae (KPC-Kp) infection were independently associated with Candida spp. isolation. Candidemia was associated with cortisone administration, KPC-Kp infection, and presence of colostomy or abdominal catheter. Administration of fluconazole was a protective factor for both Candida spp. isolation and infection, leading to selection of Candida non-albicans species. Among several risk factors, KPC-Kp infection and colonization are identified as statistically significant factors associated with Candida isolation, especially of non-albicans species.

Carbapenemase-producing Klebsiella pneumoniae bloodstream infection in critically ill patients: risk factors and predictors of mortality

A significant increase in carbapenemase-producing Klebsiella pneumoniae (CP-Kp) bacteraemias has been observed worldwide. The objective of the present work was to study the risk factors and predictors of mortality of CP-Kp bacteraemias among critically ill patients. During a 4-year period (2012–3015), a matched 1:2 case-control study was conducted. Klebsiella pneumoniae was identified by Vitek 2 technology. Antibiotic susceptibility was performed by the agar disc diffusion method and Etest. The presence of the blaKPC, blaVIM and blaNDM genes was confirmed by polymerase chain reaction (PCR). Epidemiologic data were collected from the intensive care unit (ICU) computerised database. One hundred and thirty-nine patients who developed a CP-Kp bacteraemia were matched with 278 patients. The majority of isolates (128; 92.1%) carried the blaKPC gene, seven carried both blaKPC and blaVIM, three blaVIM and one carried blaNDM. Risk factors for the development of CP-Kp bacteraemia were administration of tigecycline and number of antibiotics administered prior to CP-Kp bacteraemia. Overall, the 30-day mortality was 36.0%. Multivariate analysis revealed septic shock, Simplified Acute Physiology Score II (SAPS II) upon infection onset, adjunctive corticosteroid administration and parenteral nutrition as independent predictors of mortality, while treatment with a combination of appropriate antibiotics was identified as a predictor of good prognosis. Among septic shock patients (n = 74), Sequential Organ Failure Assessment (SOFA) score upon infection onset, adjunctive corticosteroid administration and strain carrying the blaKPC gene were independently associated with mortality, while the administration of combination treatment was identified as a predictor of a good prognosis. The administration of tigecycline predisposes to the induction of bacteraemia. Appropriate antibiotic treatment is associated with better survival, while concomitant corticosteroid treatment is associated with mortality.

Factors Influencing Linezolid-Nonsusceptible Coagulase-Negative Staphylococci Dissemination Among Patients in the Intensive Care Unit: A Retrospective Cohort Study

Background: The aim of the present study was to identify risk factors for linezolid-nonsusceptible coagulase-negative staphylococci (CNS) dissemination in the intensive care unit. Methods: Among the 246 patients included, 33 revealed a linezolid-nonsusceptible CNS-positive culture specimen, 68 were positive for linezolid-susceptible CNS and 145 served as controls. Isolates were characterized by phenotypic and genotypic methods to species level, susceptibility to antistaphylococcal agents and clones. Results: Among the 33 linezolid-nonsusceptible CNS patients, 29 revealed Staphylococcus epidermidis and 4 Staphylococcus capitis. All S. epidermidis strains belonged to the ST22 clone (by multilocus sequence typing), 26 carried both C2534T and T2504A and 3 strains were C2543T mutations. S. capitis strains were stratified as a common pulsed-field gel electrophoresis type and carried the G2576T mutation. Risk factors for linezolid-nonsusceptible CNS isolation were linezolid administration and mean number of linezolid-nonsusceptible CNS-positive patients in nearby beds per day. Conclusions: These results reinforce the aspect of rational antibiotic usage, but also highlight the need for strict infection control measures to prevent the dissemination of linezolid-nonsusceptible CNS.

Number of positive blood cultures, biofilm formation, and adhesin genes in differentiating true coagulase-negative staphylococci bacteremia from contamination

The significance of the number of coagulase-negative staphylococci (CNS)-positive blood cultures remains obscure in regards to determining true bacteremia versus contamination. The goal of this study was to determine the predictors of real CNS bloodstream infection among intensive care unit (ICU) patients. ICU patients with at least one CNS-positive blood culture were identified from the microbiology database. Biofilm formation was tested by glass tube and microtiter plate assay. mecA gene, ica operon genes (icaA, icaB, icaD), and adhesin genes (aap, bap, atlE, fbe, fnbA) were detected by polymerase chain reaction (PCR). CNS were recovered from 120 septic episodes, 20 of which were true CNS bacteremias, whereas from the remaining 100 episodes, the isolated CNS were characterized as contaminants. The number of positive blood cultures was significantly associated with true CNS bacteremia. Nineteen true bacteremic Staphylococcus epidermidis strains were compared to 38 contaminants. Biofilm synthesis was documented in 37 isolates associated with the presence of the ica operon (p = 0.048). There were 39, 26, 38, 21, and 10 strains positive for the presence of atlE, bap, fbe, aap, and fnbA genes, respectively. Rifampicin resistance, absence of severe sepsis, number of S. epidermidis-positive blood cultures, and absence of the bap gene were independently associated with true S. epidermidis bacteremia as compared to contaminant strains. The number of positive blood cultures is associated with true CNS bacteremia. The presence of adhesin genes may play a role in differentiating true infection from contamination, whereas absence of the bap gene is associated with true S. epidermidis bacteremia.

Pitfalls in the identification of Enterococcus species and the detection of vanA and vanB genes

The aims were to assess the performance of Vitek 2 in identifying enterococcal species and the implementation of GeneXpert® vanA/vanB PCR for the detection of vancomycin‐resistant enterococci (VRE). Gram‐positive cocci from clinical and environmental specimens (n = 431) suspicious of being enterococci by conventional methods were evaluated by Vitek 2. This system identified 296 Enterococcus faecium, 87 Enterococcus faecalis, 10 Enterococcus villorum, 9 Enterococcus gallinarum, 9 Enterococcus durans, 5 Enterococcus casseliflavus, 1 Enterococcus spp. and 14 isolates as Non‐Enterococcus. All strains were submitted to pulsed field gel electrophoresis (PFGE) analysis showing 64 banding patterns. Representative strains from each banding pattern were further characterized to species level by 16S rDNA sequencing. The misidentification rate by Vitek 2 to species level among 429 molecularly identified enterococci was 6% (26 isolates). Additionally, 372 rectal swabs were obtained from critically ill patients. They were evaluated for the presence of VRE by ChromID VRE combined with in‐house PCR vs GeneXpert®. GeneXpert® showed high (>92%) sensitivity, specificity, accuracy for vanA‐positive Enterococcus detection, as well as, sensitivity and specificity for vanB‐positive strains. Positive predictive value for detection of vanB‐positive enterococci by GeneXpert® vanA/vanB was low (30%). GeneXpert® showed the same efficacy as ChromID VRE in detecting vanA‐positive enterococci, but lower for vanB‐gene detection.

Performance of four different agar plate methods for rectal swabs, synergy disk tests and metallo-β-lactamase Etest for clinical isolates in detecting carbapenemase-producing Klebsiella pneumoniae.

The aims of the study were to compare four different agar plate methods in the identification of carbapenemase-producing Klebsiella pneumoniae (CP-Kp) from rectal samples and to assess the role of phenotypic methodologies in the identification of carbapenemase type from clinical K. pneumoniae isolates. Two chromogenic agars (Brilliance CRE and CHROMagar KPC) were compared to MacConkey agar plates with ertapenem (ERT) or imipenem (IMP) disks for the identification of CP-Kp from 912 rectal swabs. CP-Kp was detected in 329 samples by either agar methodology (299 K. pneumoniae carbapenemase positive, 27 Verona integron-encoded metallo-β-lactamase positive and 3 K. pneumoniae carbapenemase and Verona integron-encodedmetallo-β-lactamase positive). Sensitivity of Brilliance CRE, CHROMagar KPC and MacConkey agar plus IMP or ERT disk (inhibition zone <25 mm) was 96.8, 99.2, 67.2 and 81.8 %, while specificity was 90.9, 78.2, 98.1 and 97.9 %, respectively. Synergy meropenem-disk tests with EDTA or phenylboronic acid were used in order to detect the carbapenemase type as compared to PCR results (blaVIM, blaKPC and blaNDM) from 2515 isolates with reduced susceptibility to any of the Etest-examined carbapenems (ERT, IMP or meropenem). Metallo-β-lactamase MP/MPI Etest was applied in 616 isolates. Sensitivity was 98.4, 90.9 and 82.2 % for phenylboronic acid synergy test, EDTA synergy test and metallo-β-lactamase Etest, respectively, while their specificity was high (>97.5 %). Phenotypic methodologies can provide reliable results for the identification of carbapenemase production among K. pneumoniae isolates. Chromogenic agars can be applied in high-risk patients as part of surveillance and infection control programs.