Summary of medical phd thesis: investigation of beta lactam resistance and genes encoding beta lactamase of escherichia coli and klebsiella pneumoniae causing bloodstream infections

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENSE 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES TRINH VAN SON INVESTIGATION OF BETA-LACTAM RESISTANCE AND GENES ENCODING BETA-LACTAMASE OF ESCHERICHIA COLI AND KLEBSIELLA PNEUMONIAE CAUSING BLOODSTREAM INFECTIONS Specialty: Infectious and Tropical Diseases Educational code: 62720153 SUMMARY OF MEDICAL PhD THESIS Hanoi - 2021 THE RESEARCH WAS DONE AT: 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES Supervisors: A/Prof Le Huu Song, MD, PhD Dr Nguyên Đang Manh, MD, PhD Reviewer 1: …… Reviewer 2: …… Reviewer 3: …… The Institutional thesis defense meeting will take place at 108 Institute of Clinical Medical and Pharmaceutical Sciences At …… h … month day, year The thesis was stored at: National library of Vietnam The Library of 108 Institute of Clinical Medical and Pharmaceutical Sciences INTRODUCTION Significance of the research Bloodstream infection (BSI) is a potentially life-threatening condition and has become a major challenge for healthcare system worldwide, that have affected the million people with increasing morbidity and mortality, especially BSI caused by multidrug resistant bacteria The reports demonstrate the percentage of bacteria producing extended spectrum beta-lactamase (ESBL) are increasing from 39% to 55% in Southeast Asia Vietnam is one of the countries which have the highest prevalence of Enterobacteriaceae producing ESBL (55.1%) Previous studies have reported that the prevalence of carbapenem resistant Enterobacteriaceae in Vietnam was from 5.6% to 20% Research on antibiotic resistance genes is mainly used in investigating the epidemiology as well as transmission mechanism Some studies demonstrated the ability to use evidences of genetic resistance to guide empirical antibiotic therapy in clinical practice In Vietnam, the infections caused by Cephalosporin and Carbapenem resistant Enterobacteriaceae have been a major burden However, national data of genetic resistance encoding ESBL and carbapenemase are insufficient Therefore, the aims of this study were: Evaluating characteristics of beta-lactam resistance and distribution of genes encoding beta-lactamase of Escherichia coli and Klebsiella pneumoniae causing bloodstream infections at 108 Military Central Hospital (from October 2014 to march 2016) Assessing the value of genes encoding beta-lactamase to identify phenotypic beta-lactam resistance of bacteria and influence on treatment response MAIN SCIENTIFIC CONTRIBUTION High occurrence of broad-spectrum cephalosporin resistance of E coli and K pneumoniae causing BSI were reported The prevalence of ESBL-producing E coli and K pneumoniae were 58.3% and 22,0% respectively 26,0 % of K pneumoniae strains resisted to carbapenem There were 91.3% of E coli and 90% of K pneumoniae carrying at least one of three common genes encoding ESBL (CTXM, TEM and SHV) The CTX-M gene is valuable in diagnosis of cephalosporin resistance of E coli and K pneumoniae with the sensitivity of 77.8%90.2% The specificity of NDM-1 to identify carbapenem resistant K pneumoniae was 86,5% In the group of BSI patients caused by cephalosporin susceptible strains, the treatment response was worse in BSI patients due to strains carrying CTX-M The findings of study provide further clinical evidence for the use of antibiotic resistant genes to guide antibiotic treatment decisions in patients with BSI caused by E coli and K pneumoniae STRUCTURE OF THE THESIS The thesis includes 116 pages, with four chapters, introduction 02 pages, chapter - Literature review 34 pages, chapter - Materials and Methods 21 pages, chapter - Results 27 pages, chapter - Discussion 30 pages, conclusions and proposal 02 pages The thesis has 41 tables, 07 pictures, 12 figures, 04 diagrams, 194 references with 12 in Vietnamese and 172 in English LITERATURE REVIEW Epidemiology and etiology of bloodstream infection Bloodstream infection (BSI) have been being a challenge for healthcare system over the world with high morbidity and mortality There are approximately 19 million BSI patients per year with million deaths in the developing and poor countries In developed countries, such as United State have about 970000 BSI patients per year and numbers of patients are continuously increasing In recent years, the data on etiology of BSI demonstrated that the bacterial Gram negative was the most common pathogen, including community and hospital acquired infections Namely, E coli and K pneumoniae were the main recorded pathogens The multiple central (SENTRY) in 2019 show that S aureus, E coli and K pneumoniae were the most common pathogens causing BSI In detail, E coli was increasing from 18.5% (1997-2000) to 24.0% (2013-2016) Some reports from Vietnam and other countries in Southeast Asia showed the similar results Enterobacteriaceae producing beta-lactamase 1.2.1 Molecular mechanisms of beta-lactamase Enterobacteriaceae is a large family of Gram-negative bacteria, including a lot of important human pathogens The common mechanism of beta-lactam resistance is producing beta-lactamases, mostly ESBL and carbapenemase ESBLs are enzymes to hydrolyze broad spectrum beta-lactam, including the most of penicillin, cephalosporin (except for cephamycin) and monobactam The most common genes encoding ESBL belong to class A (as following Ampler classification) are TEM, SHV and CTX-M Gram-negative bacteria producing carbapenemases are major concern for clinical practice because of resistance to broad spectrum of beta-lactam substrates, including carbapenems The family of carbapenemases is diverse, including class A (SME, IMI, GES and KPC), class B (VIM, IMP, NDM) and class D (OXA-23, OXA-48, OXA-51) 1.2.2 Molecular epidemiology The reports show that beta-lactamases are encoded by lots of genes on plasmid or chromosome Therefore, they are easy to transmit between species of Enterobacteriaceae family The common gene family encoding ESBL are CTX-M, SHV and TEM The molecular epidemiology research performed the proportion of E coli and K pneumoniae carrying CTX-M was about from 66.7% to 99.4% Namely, the most common sub genotype was CTX-M-14, CTX-M-15 Other genes were reported, those were OXA-1, TEM-1 and SHV-1 The reports from Europe and United States about carbapenemase producing Enterobacteriaceae showed that most common genes were KPC (42%69.9%) and OXA-48 (38%) and rarer genes were NDM and VIM However, in Pacific Asia, NDM-carbapenemase and other metallo-betalactamases (IMP, VIM) are more common than KPC-beta-lactamase, especially in Southeast Asia In Vietnam, the reports about Enterobacteriaceae producing ESBL in period 2007-2013 demonstrated that prevalence of TEM, SHV, CTX-M was 83.5%-87.8%, 44.3%-62.2%, 24.6%-36%, respectively A study (2017) about strains producing ESBL causing BSI, the most common gen was CTX-M (95%), following up TEM (45%), OXA (20%) and SHV (3%) Studies on molecular mechanisms showed that NDM was a common gene identified from carbapenem-resistant strains Techniques to identify bacterial pathogens and antibiotic susceptibility testing in bloodstream infections So far, blood culture is still a “gold standard” to identify pathogens for BSI Nowadays, blood culture protocol in clinical practice is used automated platform to get real-time results The culture medium is continuous improvement to increase spectrum bacteria culture and also reduce time for culture However, blood culture methods have some limitations as low sensitivity, high blood volume imperfect growth for difficulty to culture pathogens and timeconsuming matter Antibiotic susceptibility testing (AST) is tested with different methods for each microbiology lab, such as disk diffusion or minimal inhibitory concentration (MIC) In clinical practice, AST is done by automated system such as Vitek or Phoenix system based on MIC method Other methods to identify pathogens base on polymerase chains reaction (PCR) tecnique to detect bacterial DNA in clinical samples In BSIs, the methods may use to indirectly identify bacteria from positive cultures or directly from clinical samples (blood, sputum, cerebral spinal fluid, urine) Multiplex-PCR for identification of a broad range of pathogens are developing However, the methods are not accurately consistant when compared with blood culture In additional, the methods can detect antibioic resistant genes Moreover, until now genotypic resistance are not enough evidence to assess phenotypic drug resistance and the methods are also so expensive to apply in clinical practice MATERIALS AND METHODS Materials 2.1.1 Study population 165 BSI patients were included in this study They were diagnosed and treated at the 108 Military Central Hospital from Oct, 2014 to May, 2016 In which, 115 patients caused by E coli and 50 patients caused by K pneumoniae 2.1.2 Inclusion criteria Bloodstream infections were diagnosed with criteria following Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012 and documented infections were positive blood culture with E coli or K pneumoniae 2.1.3 Exclusion criteria It did not match the results of bacteria between culture bottles or polyinfection Patients or their relatives did not agree to join the study Methods 2.2.1 Study design: Observational study 2.2.2 Research parameters 2.2.2.1 Clinical and subclinical parameters Clinical and subclinical characteristics of BSI patients were recorded with the same study report for each patient Clinical variables were examined by physicians and subclinical variables were tested with routine tests in the hospital 2.2.2.2 Bacterial culture and antibiotic susceptibility testing Blood cultures were collected when patients admitted with community infections or started onset of BSI with hospital acquired infections Bacterial identification and antibiotic susceptibility testing were done with Vitek II Compact System (BioMerieux, France) Antibiotic substances Amocixillin/Acid were Clavulanic tested (AMC), including Ampicillin, Piperacillin/Tazobacbam (TZP), Cefotaxime (CTX), Ceftazidime (CAZ), Cefepime (FEP), Ertapenem (ETP), Imipenem (IPM), Meropenem (MEM) 2.2.2.3 Genes encoding beta-lactamases Genes encoding beta-lactamases were investigated including: six genes encoding ESBL (TEM, SHV, CTX-M, VEB, PER, GES) and nine genes encoding carbapenemases (KPC, AIM, IMP, VIM, SPM, NDM-1, OXA-58, OXA-23 and OXA-48) Combination of genes encoding beta-lactamse was also reported such as 3-POS, that was strains carrying all of three genes CTX-M, TEM and SHV 2.2.2.4 Treatment response: evaluated by existence of septic shock, fatality rate, duration of fever after diagnosis and length of hospital stay Statistical analysis Statistical analyses were performed using the SPSS software v.23.0 (IBM Corporation, USA) Continuous variables are presented as mean ± standard deviation Categorical variables are given as frequencies with percentages and comparisons of categorical variables between groups were performed using chi-square and Fisher’s exact tests The level of significance was set at p-values < 0.05 Ethics statements Ethical approval was obtained from the Ethics Committee and the Review Board of the 108 Military Central Hospital The Ethics Committee also approved a waiver of informed consent to participate in this study because of its retrospective design All patient data was anonymized prior to the analysis RESULTS General characteristics Table 3.1 Baseline characteristics of patient cohort Characteristics E coli BSIs (n=115) 70(60.9) K pneumoniae BSIs (n=50) 37(74.0) Total (n=165) 107(64.8) Mean of age (years) 62.3±16.2 62.0±17.2 62.3±16.5  60 years old n (%) 62(53.9) 26(52.0) 88(53.3) Pre-existing conditions n (%) 73(63.5) 27(54.0) 100(60.6) Sex (male) n (%) Primary source infection n (%) 95(82.6) 44(88.0) 139(84.2) Mean of SOFA (points) 3.36±3.05 3.62±3.1 3.44±3.06 While blood cell (G/L) 16.9±13,7 16.4±8.9 16.8±12.4 Neutrophile (G/L) 13.7±9.9 13.9±8.0 13.8±9.3 Platelet (G/L) 190±118 170±130 184±122 Prothrombin (%) Pro-calcitonin (ng/L) Lactate (mmol/L) Duration of fever after diagnosis (days) Length of hospital stay (days) 76.5±22.8 81.7±21.6 77.7±22.5 32.53±38.23 29.54±32.49 31.58±36.41 5.34±3.53 4.89±3.18 5.14±3.34 5.2±2.5 6.7±3.8 5.6±3.0 19.9±14.7 27.7±27.6 22.3±19.8 Septic shock n (%) 19(16.5) 14(28.0) 33(20.0%) Mortality n (%) 18(15.7) 12(24.0) 30(18.2%) The results show that the most patients were male (64.8%) and over 60 years old (53.3%) with pre-existing conditions The primary source infections were reported 82.6% with E coli-BSIs and 88.0% with K pneumoniae-BSIs Subclinical of BSI patients performed increasing while blood cell with the most Neutrophil, pro-calcitonin and serum lactate Mean of SOFA was higher than points There were not different significance subclinical variables between E coliBSIs and K pneumoniae-BSIs The ratio of septic shock and mortality were 20.0% and 18.2% respectively 11 12/50 25.0% 20.0% 6/50 15.0% 9/115 10.0% 5/115 5.0% 0/115 0.0% 1/50 0/115 1/50 E coli NDM-1 7.8% VIM 4.3% KPC 0.0% OXA-48 0.0% K pneumoniae 24.0% 12.0% 2.0% 2.0% Figure 3.2 Contributions of genes encoding carbapenemase There were 12/50 (24%) of K pneumoniae carrying NDM-1, that was higher than E coli 9/115(7.8%) 5/115 (4,3%) of E coli and 6/50 (12%) of K pneumoniae were detected with VIM 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 00% 105/115 45/50 20/5042/11521/50 24/50 43/115 21/50 19/50 18% 1/115 0/115 TEM+SHV E coli 00% TEM+ CTX-M 37% K pneumoniae 40% 42% 0/115 00% SHV+ CTX-M 01% 1-POS 2-POS 3-POS TSCN 91% 37% 00% 00% 42% 90% 48% 38% 18% Figure 3.3 Contributions of strains carrying combination genes High prevalence of strains was detected with at least one of three gen (1-POS), 91.3% with E coli and 90% with K pneumoniae There were 38% of K pneumoniae carrying all of three genes (TEM, SHV and CTX-M) and 9/50 (18.0%) of K pneumoniae carrying all of genes (TEM; SHV; CTX-M and NDM-1) However, there were not any E coli strains carrying 3-POS or TSCN 12 Correlation between genotypic resistance and beta-lactam resistance and influence on the outcome of BSI patients 3.3.1 Correlation between genotypic resistance and phenotypic betalactam resistance Table 3.7 Correlation between genotype and phenotype of Penicillin and Cephalosporin resistance of E coli Genes Antibiotics Positive (n=67) ESBL CTX CAZ FEP AMC TZP Negative (n=48) p Non-Sus (n=81) Sus (n=34) p Non-Sus (n=53) Sus (n=62) p Non-Sus (n=41) Sus (n=68) p Non-Sus (n=48) Sus (n=67) p Non-Sus (n=22) Sus (n=93) p TEM n (%) 38 (56.7) 29 (60.4) CTX-M n (%) 58 (86.6) 22 (45.8) TC n (%) 31 (46.3) 11 (22.9) 1-POS n (%) 65 (97.0) 40 (83.3) 2-POS n (%) 31 (46.3) 12 (25.0) NoT n (%) 40 (60.4) 29 (59.7) NoC n (%) 60 (89.6) 22 (45.8) 0.692 46 (56.8) 21 (61.8) 0.001 69 (85.2) 11 (32.4) 0.010 37 (45.7) (14.7) 0.010 78 (96.3) 27 (79.4) 0.020 37 (45.7) (17.6) 0.938 48 (59.3) 21 (61.8) 0.001 71 (87.7) 11 (32.4) 0.622 28 (52.8) 39 (62.9) 0.001 45 (84.9) 35 (56.5) 0.002 22 (41.5) 20 (32.3) 0.003 51 (96.2) 54 (87.1) 0.005 23 (43.4) 20 (32.3) 0.802 29 (54.7) 40 (64.5) 0.001 46 (86.8) 36 (58.1) 0.275 21 (51.2) 42 (61.8) 0.001 37 (90.2) 37 (54.4) 0.304 18 (43.9) 20 (29.4) 0.083 40 (97.6) 59 (86.8) 0.218 19 (46.3) 20 (29.4) 0.285 22 (53.7) 43 (63.2) 0.001 38 (92.7) 38 (55.9) 0.280 35 (72.9) 32 (47.8) 0.001 32 (66.7) 48 (71.6) 0.124 20 (41.7) 22 (32.8) 0.059 47 (97.9) 58 (86.6) 0.074 20 (41.7) 22 (34.3) 0.324 36 (75.0) 33 (49.3) 0.001 34 (70.8) 48 (71.6) 0.007 15 (68.2) 52 (55.9) 0.567 16 (72.7) 64 (68.8) 0.332 10 (45.5) 32 (34.4) 0.033 21 (95.5) 84 (90.3) 0.423 10 (45.5) 33 (35.5) 0.005 15 (68.2) 54 (58.1) 0.925 16 (72.7) 66 (71.0) 0.294 0.720 0.333 0.442 0.385 0.384 0.870 In all of genes encoding beta-lactamases of E coli strains, CTX-M and NoC were detected significant higher in Cephalosporin resistant E coli than the rest group with p = 0.001 TEM-E coli was significant higher in AMC non-susceptible E coli than susceptible group with p=0.007 13 Table 3.10 Correlation between genotype and phenotype of Penicillin and Cephalosporin resistance of K pneumoniae Genes Antibiotics Positive (n=11) ESBL Negative (n=39) p Non-Sus (n=24) CTX Sus (n=26) p Non-Sus (n=27) CAZ Sus (n=23) p Non-Sus (n=19) FEP Sus (n=29) p Non-Sus (n=28) AMC Sus (n=22) p Non-Sus (n=24) TZP Sus (n=26) p TEM n (%) 10 (90.9) SHV n (%) (81.8) CTX-M n (%) 10 (90.9) TC n (%) (81.8) NoT n (%) 10 (90.9) NoC n (%) 11 (100) NoS n (%) 11 (100) 13 (33.3) 33 (84.6) 13 (33.3) 12 (30.8) 14 (35.9) 14 (35.9) 33 (84.6) 0.001 0.823 0.001 0.002 0.001 0.001 0.166 18 (75.0) 20 (83.3) 19 (79.2) 17 (70.8) 19 (79.2) 21 (87.5) 22 (91.7) (19.2) 22 (84.6) (15.4) (15.4) (19.2) (15.4) 22 (84.6) 0.001 0.902 0.001 0.001 0.001 0.001 0.443 20 (74.1) 23 (85.2) 21 (77.8) 19 (70.4) 21 (77.8) 23 (85.2) 25 (92.6) (13.0) 19 (82.6) (8.7) (8.7) (13.0) (8.7) 19 (82.6) 0.001 0.804 0.001 0.001 0.001 0.001 0.279 15 (78.9) 17 (89.5) 17 (89.5) 15 (78.9) 15 (78.9) 17 (89.5) 17 (89.5) (24.1) 23 (79.3) (17.2) (17.2) (24.1) (20.7) 25 (86.2) 0.001 0.356 0.001 0.001 0.001 0.001 0.738 20 (71.4) 25 (89.3) 22 (78.6) 20 (71.4) 21 (75.0) 23 (82.1) 26 (92.9) (13.6) 17 (77.3) (4.5) (4.5) (13.6) (9.1) 18 (81.8) 0.001 0.250 0.001 0.001 0.001 0.001 0.233 19 (79.2) 21 (87.5) 20 (83.3) 19 (79.2) 20 (83.3) 21 (87.5) 22 (91.7) (15.4) 21 (80.8) (11.5) (7.7) (15.4) (15.4) 22 (84.6) 0.001 0.517 0.001 0.001 0.001 0.001 0.443 In all of genes encoding beta-lactamase, TEM, CTX-M, NoC and NoT were the most contribution of Cephalosporin resistant K pneumoniae The distribution of SHV between susceptible and nonsusceptible cephalosporin group were not different significance 14 Table 3.13 Correlation between genotype and phenotype of Carbapenem resistance of K pneumoniae Carbapenem Genotypes Non- Susceptible (n=13) Susceptible (n=37) p (53.8) (13.5) 0.003 (0) (16.2) 0.122 3-POS n (%) (61.5) 11 (29.7) 0.042 2-POS n (%) 10 (76.9) 14 (37.8) 0.015 TSCN n (%) (46.2) (8.1) 0.002 NDM-1 n (%) VIM n (%) CN n (%) (46.2) (10.8) 0.006 NoC n (%) 11 (84.6) 14 (37.8) 0.004 NoT n (%) 10 (76.9) 14 (37.8) 0.015 NoS n (%) 11 (84.6) 33 (89.2) 0.662 There were 13 carbapenem non-susceptible K pneumoniae in our results The percentage of NDM-1; 3-POS; TSCN and CN were 7/13 (53.8%); 8/13 (61.5%); 6/13 (46.2%) and 6/13 (46.2%) respectively Moreover, NDM-1 was detected in carbapenem nonsusceptible K pneumoniae strains was signifficant higher than carbapenem susceptible K pneumoniae strains 3.3.2 The value of genes encoding beta-lactamase to predict betalactam resistance Table 3.15 The value of CTX-M and NoC to predict beta-lactam resistant E coli Value ESBL CTX CAZ FEP AMC TZP CTX-M NoC CTX-M NoC CTX-M NoC CTX-M NoC CTX-M NoC CTX-M NoC Sen (%) Spe (%) PPV (%) NPV (%) Accu (%) 86.6 89.6 85.2 87.7 84.9 86.4 90.2 92.7 66.7 70.8 72.7 72.7 54.2 54.2 67.6 67.6 43.5 41.9 45.6 44.1 28.4 28.4 31.2 29.0 72.5 73.2 86.3 86.6 56.3 56.1 50.0 50.0 40.0 41.5 20.0 19.5 74.3 78.8 65.7 69.7 77.1 78.8 88.6 90.9 54.3 57.6 82.9 81.8 73.0 74.8 80.0 81.7 62.6 62.6 62.4 62.4 44.3 46.1 39.1 37.4 15 The value of CTX-M to predict cephalosporin resistance was 84.9%-90.2% sensitivity; however, the specificity was from 43.5% to 67.6% When combination between NDM-1 and CTX-M, they were increasing sensitivity but not specificity to predict cephalosporin resistance Table 3.16 The value of genes to predict cephalosporin resistant K pneumoniae Value ESBL Sen (%) Spe (%) PPV (%) NPV (%) Accu (%) TEM 90.9 66.7 43.5 96.3 72.0 CTX-M 90.9 66.7 43.5 96.3 72.0 NoT 90.9 64.1 41.7 96.2 70.0 NoC 100 64.1 44.0 100 72.0 80.8 78.3 77.8 78.0 84.6 82.6 81.5 82.0 80.8 79.2 80.8 80.0 84.6 84.0 88.0 86.0 87.0 87.0 74.1 80.0 91.3 91.3 77.8 84.0 87.0 87.5 76.9 82.0 91.3 92.0 84.0 88.0 75.9 68.2 84.6 77.1 TEM CTX-M CTX NoT NoC TEM CTX-M CAZ NoT NoC FEP 75.0 79.2 79.2 87.5 74.1 77.8 77.8 TEM 85.2 78.9 CTX-M 89.5 82.8 77.3 92.3 85.4 NoT 78.9 75.9 68.2 84.6 77.1 NoC 89.5 79.3 73.9 92.0 83.3 TEM and CTX-M were potential prediction cephalosporin resistant K pneumoniae The sensitivity was from 74.1% to 90.9% and the specificity was from 66.7% to 91.3% Combination NDM-1 with TEM or CTX-M, that made increased sensitivity to predict cephalosporin resistance but not specificity 16 Table 3.18 The value of genotypic resistance to predict carbapenem resistant K pneumoniae Value Sen (%) Spe (%) PPV (%) NPV (%) Accu (%) NDM-1 53.8 86.5 58.3 84.2 78.0 3-POS TSCN CN NoC 61.5 46.2 46.2 84.6 70.3 91.9 89.2 62.2 42.1 66.7 60.0 44.0 83.9 82.9 82.5 92.0 68.0 80.0 78.0 68.0 NDM-1 gene is a good candidate to predict carbapenem resistant K pneumoniae with 86.5% specificity Strains carrying all of four genes (TEM, SHV, CTX-M and NDM-1) had high specificity (91.9%) but moderate sensitivity (46.2%) 11/42 p=0.399 p=0.236 7/47 9/55 8/37 p=0.205 5/15 10/52 p=0.473 8/45 9/35 3.3.3 Relation between genotypic resistance and clinical outcome ESBL negative Susceptible to CTX Susceptible to CAZ Susceptible to FEP CTX-M positive 25.7% 33.3% 21.6% 26.2% CTX-M negative 19.2% 17.8% 14.6% 16.4% 5/48 6/45 p=0.253 7/55 9/42 p=0.264 p=0.230 7/37 4/15 p=0.378 8/52 8/35 Figure 3.4 Contribution of CTX-M on septic shock patients caused by susceptible cephalosporin strains ESBL negative Susceptible to CTX Susceptible to CAZ Susceptible to FEP CTX-M positive 22.9% 26.7% 18.9% 21.4% CTX-M negative 15.4% 13.3% 10.4% 12.7% Figure 3.5 Contribution of CTX-M on mortality patients caused by susceptible cephalosporin strains 17 In the BSI patients caused by cephalosporin susceptible strains, the proportion of septic shock (fig 3.6) and mortality (fig 3.7) were higher in group with CTX-M positive than group with CTX-M negative However, the difference was not significant with p > 0.05 Table 3.19 Duration of fever after diagnosis in BSI patients caused by cephalosporin susceptible strains Phenotypic resistance ESBL negative Susceptible to CTX Susceptible to CAZ Susceptible to FEP Duration of fever after diagnosis (days) (Mean ± SD (n)) CTX-M (+) CTX-M (-) p 7.0±4.6 (n=27) 5.2±2.0 (n=44) 0.027 7.8±6.2 (n=11) 15.0±1.9 (n=39) 0.016 6.1±4.2 (n=30) 4.9±2.0 (n=43) 0.094 6.0±4.0 (n=33) 5.0±2.0 (n=48) 0.138 In BSI group caused by cephalosporin susceptible strains, the duration of fever after diagnosis was significant longer in group with CTX-M positive than group with CTX-M negative Table 3.1 The length of hospital stays in septic patients caused by cephalosporin susceptible strains ESBL negative Susceptible to CTX Length of hospital stay (days) (Mean ± SD (n)) CTX-M positive CTX-M negative 31.9±29.1 (n=35) 15.3±9.9 (n=52) 26.4±16.8 (n=15) 13.9±8.0 (n=45) p 0.001 0.001 Susceptible to CAZ Susceptible to FEP 20.5±14.8 (n=37) 20.6±14.4 (n=42) 0.011 0.035 Phenotypic resistance 14.1±7.7 (n=48) 15.5±9.2 (n=55) In BSI group caused by cephalosporin susceptible strains, the length of hospital stay was significant longer in group with CTX-M positive than group with CTX-M negative with p < 0.05 18 Septic shock 45.0% 40.0% Mortality p=0.482 p=0.406 p=0.380 p=0.786 35.0% 30.0% 2/5 7/32 6/26 3/11 8/32 10.0% 6/26 15.0% 4/11 20.0% 2/5 25.0% 5.0% 0.0% 3POS NDM-1 3POS NDM-1 Positive 36.4% 40.0% 27.3% 40.0% Negative 23.1% 25.0% 23.1% 21.9% Figure 3.6 Distribution of shock and mortality of patients caused by Carbapenem susceptible K pneumoniae In BSI patients caused by carbapenem susceptible K pneumoniae, the percentage of sock and mortality were higher in group with 3-POS positive (36.4% and 27.3%) or NDM-1 positive (40% and 40%) than group with 3-POS negative (23.1% and 23.1%) or NDM-1 negative (25% and 21.9%), respectively Table 3.2 The length of hospital stays in BSI patients caused by carbapenem susceptible K pneumoniae Genotypic resistance Length of hospital stay (days) (Mean ± SD (n)) Positive Negative p 3-POS 38.2±21.7 (n=11) 16.4±11.2 (n=26) 0.001 NDM-1 44.8±23.5 (n=5) 19.5±14.5 (n=32) 0.002 In patients caused by carbapenem susceptible K pneumoniae, the length of hospital stay was longer in group with NDM-1 or 3-POS positive than group with NDM-1 or 3-POS negative The difference was significance with p < 0.05 ... aims of this study were: Evaluating characteristics of beta- lactam resistance and distribution of genes encoding beta- lactamase of Escherichia coli and Klebsiella pneumoniae causing bloodstream infections. .. 20.0% and 18.2% respectively 9 The status of beta- lactam resistance and characteristic of genes encoding beta- lactamases 3.2.1 The status of beta- lactam resistance Table 3.5 The percentage of cephalosporin... (MEM) 2.2.2.3 Genes encoding beta- lactamases Genes encoding beta- lactamases were investigated including: six genes encoding ESBL (TEM, SHV, CTX-M, VEB, PER, GES) and nine genes encoding carbapenemases