Microbiological Characteristics Of Patients Research Articles

Evaluation of ompK36 allele groups on clinical characteristics and virulence features of Klebsiella pneumoniae from bacteremia.

This study investigated the implications of ompK36 allele groups on clinical and microbiological features of patients with Klebsiella pneumoniae bacteremia. A total of 80 K. pneumoniae bloodstream isolates were collected and then divided into four ompK36 allele groups. Clinical characteristics, bacterial antibiotic resistance and virulence determinants were analyzed, including resistance and virulence genes, hypermucoviscosity phenotype, K capsule serotypes, biofilm formation, serum killing, neutrophil phagocytosis, and mouse lethality studies. 78 isolates were classified into four ompK36 variants, designated groups A (34), B (6), C (26), and D (12), respectively; 2 isolate was untypeable. OmpK36 group C isolates carried higher frequencies of K1/K2 capsule serotypes, hypermucoviscosity phenotype, rmpA gene, allS gene, iroB gene, aerobactin gene, or rmpA2 gene than non-C group isolates. OmpK36 group C isolates were significantly more virulent, as higher serum resistance, higher anti-phagocytosis and higher mouse lethality, than OmpK36 non-C group isolates, except for similar biofilm formation capability. The K20 isolates probably has low expression rates of rmpA and rmpA2 for hypermucoviscosity phenotype. The biofilm formation was significantly associated with ESBL production. OmpK36 group C isolates were more frequently detected in patients with community-acquired bloodstream infection. However, significant underlying diseases and prior use of carbapenem were highly prevalent in patients with OmpK36 non-C group isolates infection. ESBL production was apparently higher in non-C group but did not reach statistical significance. Our results suggest that the OmpK36 group C K.pneumoniae is more associated with community-acquired infection with a lower frequency of underlying illness, but with significantly more virulence in bloodstream infection. This would give a remind that clinicians should be aware of such clinical impacts of the ompK36 allele group.

Clinical, Radiological, and Microbiological Characteristics of Mycobacterium simiae Infection in 97 Patients.

Mycobacterium simiae is a rare species of slow-growing nontuberculous mycobacteria (NTM). From 2002 to 2017, we conducted a retrospective study that included all patients with NTM-positive respiratory samples detected in two university hospitals of the French overseas department of Reunion Island. We recorded the prevalence of M. simiae in this cohort, as well as the clinical, radiological, and microbiological features of patients with at least 1 sample positive for M. simiae In our cohort, 97 patients (15.1%) were positive for M. simiae Twenty-one patients (21.6%) met the American Thoracic Society (ATS) criteria for infection. M. simiae infection was associated with bronchiectasis, micronodular lesions, and weight loss. Antibiotic susceptibility testing was performed for 60 patients, and the isolates were found to have low susceptibility to antibiotics, except for amikacin, fluoroquinolones, and clarithromycin. Treatment failed for 4 of the 8 patients treated for M. simiae infection. Here, we describe a specific cluster corresponding to a large cohort of patients with M. simiae, a rare nontuberculous mycobacterium associated with low pathogenicity and poor susceptibility to antibiotics.

A comparative study of acute nonemphysematous pyelonephritis in diabetics and nondiabetics from a tertiary care hospital in South India

AIM: The aim of this study is to analyze the clinical, biochemical, and microbiological characteristics of patients with acute nonemphysematous pyelonephritis in diabetics and nondiabetics from Indian subcontinent. MATERIALS AND METHODS: It is a retrospective study conducted at a tertiary care hospital from January 2012 to August 2016. The hospital medical records were searched electronically for clinical, biochemical, and microbiologic data. RESULTS: A total of 177 patients were enrolled for the study. in the diabetic group (51.9 years) was slightly higher than the nondiabetic patients (45.7 years). Nondiabetic patients presented late when compared to diabetics (6.38 days against 4.7 days). About 11.5% in diabetics against 5.8% in nondiabetics had recurrent urinary tract infection. The urine culture in the diabetics and nondiabetics showed positive growth in 43.8% and 43.2% of cases, respectively, with Escherichia coli, extended-spectrum β-lactamase, and Klebsiella being commonly identified organisms. Blood culture specimens in both the groups had high negative results with 86.5% in diabetics and 98.8% in nondiabetics. Over 90% of patients in either group responded to treatment with either antibiotic alone or in combination with double-J stenting. Temporary hemodialysis was required in 8% in diabetic group and 6% in nondiabetic group. Maintenance hemodialysis was required in approximately 3% of diabetic patients. CONCLUSION: In our study, the incidence of acute pyelonephritis was found to be higher in patients in their fifth decade of life. Diabetics had more severe infection at presentation and consequently had poorer outcomes in terms of residual renal function and need for dialysis.

Tuberculosis por Mycobacterium bovis en la población de Castilla y León (España), 2006-2015

IntroductionThe annual incidence of tuberculosis (TB) from Mycobacterium bovis in humans has considerably declined in industrialised countries since the early twentieth century. The objective of this study was to determine the epidemiological, clinical and microbiological characteristics of patients with this illness in Castile and León (CyL). MethodsRetrospective study of all M. bovis TB cases in CyL over a 10-year period, comparing the risk factors, the epidemiology and the clinical course between pulmonary (PTB) and extrapulmonary TB (EPTB). Results75 cases of TB were due to M. bovis: 45 PTB and 31 EPTB. The annual incidence of TB due to M. bovis was 0.3 cases per 100,000. It remained stable between the first and second five-year period (0.27 vs. 0.33, p=0.656). However, the overall incidence of TB fell in both five-year periods (13.58 vs. 10.71, p<0.0001). The mean age was 66.2+21.3 years, mainly men (63%) and Spanish patients (92%). PTB was significantly more frequent in men, aged over 66 years, with immunosuppressive conditions or who were smokers. Mortality was 9%, associated with higher age, immunosuppression or treatment different from that recommended by the WHO. ConclusionsThe incidence of M. bovis TB in CyL was higher than that for Spain and for other European countries, and remained stable despite the decreased the TB due to MTC. It affected mostly Spanish-born patients who lived in rural areas and with a high mean age.

Clinical and microbiological characteristics of patients with bacteremia caused by Campylobacter species with an emphasis on the subspecies of C. fetus.

This study was intended to investigate the clinical and microbiological characteristics of patients with bacteremia caused by Campylobacter species. From April 1998 to May 2014, 56 adults with bacteremia caused by Campylobacter species were evaluated. These Campylobacter species isolates were confirmed to the species level using 16S rRNA gene sequencing (all isolates) and multiplex PCR analysis (for C. fetus only). The performance of identification for Campylobacter species by the Bruker Biotyper MALDI-TOF MS was evaluated. The genetic relatedness of C. fetus isolates was analyzed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). The leading underlying medical conditions of these patients were malignancy (46.4%), hypertension (35.7%), and liver cirrhosis (23.2%). The overall 30-day mortality rate was 5.4%. Using 16S rRNA sequencing analysis, 26 isolates of C. coli, 11 of C. jejuni, and 19 of C. fetus, including 15 C. fetus subsp. fetus and five C. fetus subsp. venerealis, were identified. Among the five C. fetus subsp. venerealis isolates recognized by 16S rRNA gene sequencing, only twoisolates were C. fetus subsp. venerealis by multiplex PCR method. The Bruker Biotyper MALDI-TOF MS failed to correctly identify C. fetus subsp. venerealis isolates. MLST analysis of C. fetus isolates revealed three STs: ST20 (n=12), ST11 (n=5), and ST57 (n=2), which were compatible with three major PFGE clusters. Database expansion of MALDI-TOF MS for the correct identification of C. fetus to subspecies levels is needed. A novel clone of ST57-PFGE Cluster C of C. fetus subsp. venerealis was noted.

Epidemiological, Clinical and Microbiological Characteristics of Patients with Post-Traumatic Osteomyelitis of Limb Fractures in Southwest China: A Hospital-Based Study.

Objective To determine the epidemiological, clinical and microbiological characteristics, of patients with post-traumatic osteomyelitis of extremity fractures, and provide evidence-based guidelines for early diagnosis and treatment, including empiric antibiotic therapy.Methods Human subject research was performed using institutional review board approved protocols. A retrospective chart review was conducted on 5,368 patients diagnosed with extremity traumatic fractures from January 1, 2012 to December 31, 2015, to identify osteomyelitis patients. Records from the Microbiology Department were reviewed, and patients with a positive wound culture, or bone biopsy culture, were selected for the study. Microbial suceptability was determined by the M-100-S22 protocol (Clinical & Laboratory Standards Institute® (CLSI) 2012 USA). Additional clinical information, including data on patients' baseline epidemiological, clinical, and microbiological records was collected from all available charts, and reviewed using a designed protocol.Results 84 (1.56%) patients were diagnosed with osteomyelitis based on a positive culture result. The most prevalent comorbidities in these patients were compartment syndrome, diabetes and hypertension. The most commonly involved infected site was the tibia-fibula (47.62%). 66 (78.57%) of these cases were monomicrobial, and 18 cases (21.43%) were polymicrobial. The infections were predominantly caused by Gram-positive bacteria (56, 53.85%). The most common Gram-positive bacteria were Staphylococcus aureus (39 cases, 37.50%) and S. epidermidis (6 cases, 5.77%), which were sensitive to ampicillin, synercid/ dalfopristin, linezolid, tigecycline, macrodantin, and vancomycin. S. aureus was the most common pathogen in both monomicrobial and polymicrobial cases. All 17 cases of MRSA infection were sensitive to Imezolid, ampicillin, synercid/ dalfopristin, linezolid, tigecycline, furadantin, piperacillin/yaz, rifampicin, and vancomycin, respectively. The most common Gram-negative bacteria were E. coli (16 cases, 15.38%) and Enterobacter cloacae (11 cases, 10.58%), which were sensitive to thienamycin.Conclusions In this study, the overall rate of post-traumatic osteomyelitis of limb fractures (1.56%) is lower than the national average rate (2.6-7.8%), for major medical centers in China. The main medical comorbidities were compartment syndrome, diabetes mellitus and hypertension. The most common infection was monomicrobial in lower extremities. S. aureus was the most common pathogen, which presented in 39 (37.50%) cases, and 17 of these (43.59%) were caused by MRSA. These findings can guide empiric antibiotic therapy in Southwest China for osteomyelitis in patients with traumatic limb fractures.

Clinical and Microbiological Characteristics of Bacteroides Prosthetic Joint Infections.

Clinical and microbiological characteristics of patients with Bacteroides prosthetic joint infection (PJI) have not been well described in the literature. The aim of this retrospective cohort study was to assess the outcome of patients with Bacteroides PJI and to review risk factors associated with failure of therapy. Between 1/1969 and 12/2012, 20 episodes of Bacteroides PJI in 17 patients were identified at our institution. The mean age of the patients in this cohort at the time of diagnosis was 55.6 years; 59% (n=10) had knee involvement. Twenty four percent (n=4) had diabetes mellitus, and 24% had a history of either gastrointestinal (GI) or genitourinary (GU) pathology prior to the diagnosis of PJI. Thirty five percent (n=6) were immunosuppressed. The initial medical/surgical strategy was resection arthroplasty (n=9, 50%) or debridement and implant retention (n=5, 28%). Thirty seven percent (n=7) were treated with metronidazole. Eighty percent (n=4) of patients that failed therapy had undergone debridement and retention of their prosthesis, as compared to none of those treated with resection arthroplasty. Seventy percent (n=14) of patient episodes were infection free at their last date of follow up. In conclusion, a significant proportion of patients with Bacteroides PJI are immunosuppressed and have an underlying GI or GU tract pathology. Retention and debridement of the prosthesis is associated with a higher risk of treatment failure.

Urinary tract infection leading to hospital admission during the first year after kidney transplantation: A retrospective cohort study

IntroductionUrinary tract infection (UTI) is the most common infectious problem in kidney transplant recipients (KTR). It has been associated with risk factors inherent to the transplant and it could negatively affect clinical outcomes. The aim of this study was to describe demographic, clinical and microbiological characteristics of patients with UTI. MethodsWe underwent a retrospective study reviewing the database of kidney transplants patients in a national reference center in Colombia. We included patients admitted for inpatient treatment related to urinary tract infection in the first year after transplantation. ResultsWe describe clinical information from 65 patients, the mean age was 46 years, the most common comorbidity was hypertension (n=48/62, 77.4%) followed by diabetes mellitus (n=11/62, 17.7%); 77% (n=50/65) of the infections were diagnosed in the first 6 months after transplant and 70% (n=45/65) had pyelonephritis. Acute dysfunction of the graft was the most common complication in 59% (n=33/56) of cases. The most common etiological agent described was E. coli in 67% (n=37/55) of patients followed by Klebsiella pneumoniae (n=13/55). Bacteremia was present in 25% of cases. Infection with extended-spectrum betalactamases producing bacteria was present in 42% (n=18/42) of our isolations and multidrug resistance was documented in 39% (n=21/54) of isolates. ConclusionMost UTI leading to hospitalization in KTR occur in the first six months. Pyelonephritis explains the majority of clinical diagnosis. The rate of blood stream infections and multidrug resistance bacteria is high, justifying an empiric broad-spectrum antibiotic treatment.

Candida haemulonii Complex Species, Brazil, January 2010-March 2015.

Candida haemulonii Complex Species, Brazil, January 2010-March 2015.

Diagnosis and features of hospital-acquired pneumonia: a retrospective cohort study

BackgroundHospital-acquired pneumonia (HAP) is defined as radiologically confirmed pneumonia occurring ≥48 h after hospitalization, in non-intubated patients. Empirical treatment regimens use broad-spectrum antimicrobials.AimTo evaluate the accuracy of the diagnosis of HAP and to describe the demographic and microbiological features of patients with HAP.MethodsMedical and surgical inpatients receiving intravenous antimicrobials for a clinical diagnosis of HAP at a UK tertiary care hospital between April 2013 and 2014 were identified. Demographic and clinical details were recorded.FindingsA total of 166 adult patients with a clinical diagnosis of HAP were identified. Broad-spectrum antimicrobials were prescribed, primarily piperacillin–tazobactam (57.2%) and co-amoxiclav (12.5%). Sputum from 24.7% of patients was obtained for culture. Sixty-five percent of patients had radiological evidence of new/progressive infiltrate at the time of HAP treatment, therefore meeting HAP diagnostic criteria (2005 American Thoracic Society/Infectious Diseases Society of America guidelines). Radiologically confirmed HAP was associated with higher levels of inflammatory markers and sputum culture positivity. Previous surgery and/or endotracheal intubation were associated with radiologically confirmed HAP. A bacterial pathogen was identified from 17/35 sputum samples from radiologically confirmed HAP patients. These were Gram-negative bacilli (N = 11) or Staphylococcus aureus (N = 6). Gram-negative bacteria tended to be resistant to co-amoxiclav, but susceptible to ciprofloxacin, piperacillin–tazobactam and meropenem. Five of the six S. aureus isolates were meticillin susceptible and all were susceptible to doxycycline.ConclusionIn ward-level hospital practice ‘HAP’ is an over-used diagnosis that may be inaccurate in 35% of cases when objective radiological criteria are applied. Radiologically confirmed HAP represents a distinct clinical and microbiological phenotype. Potential risk factors were identified that could represent targets for preventive interventions.

Risk Factors and Microbiological Features of Patients Hospitalized for Microbial Keratitis

We conducted a retrospective, cross-sectional study to analyze predisposing factors, clinical features, and microbiological characteristics of patients with microbial keratitis hospitalized over 10 years.The medical records of 558 patients who were diagnosed with microbial keratitis and admitted to Chang Gung Memorial Hospital (CGMH), a referral center in Taiwan, from January 1, 2003 to December 31, 2012 were reviewed. Demographics, predisposing factors, isolated organisms, treatment, and hospital stay were recorded. Yearly trends were tested using a linear-by-linear association.Contact lens wear was the most common predisposing factor (31.4%), followed by ocular and systemic diseases (26.3%) and trauma (23.5%). Contact lens-related infectious keratitis increased year by year (P = 0.011). Pseudomonas aeruginosa was the most commonly isolated organism (28%), followed by fungi (17.6%) and coagulase-negative Staphylococcus (5.4%). Except for Serratia marcescens, the identified organisms did not change over 10 years. Most bacterial infections were controlled using antimicrobial treatment, but more than half of patients with fungal keratitis required surgical interventions. The mean hospital stay was 13.7 ± 11.5 days. Previous ocular surgery, large ulcer size, nontuberculous myycobacteris infection, and surgery during admission were related to prolonged hospital stay.In Taiwan, contact lens-related pseudomonal keratitis remained the most common cause of microbial keratitis in patients hospitalized from 2003 to 2012.

Clinical manifestations of non-O1 Vibrio cholerae infections.

BackgroundInfections caused by non-O1 Vibrio cholera are uncommon. The aim of our study was to investigate the clinical and microbiological characteristics of patients with non-O1 V. cholera infections.MethodsThe clinical charts of all patients with non-O1 V. cholera infections and who were treated in two hospitals in Taiwan were retrospectively reviewed.ResultsFrom July 2009 to June 2014, a total of 83 patients with non-O1 V. cholera infections were identified based on the databank of the bacteriology laboratories of two hospitals. The overall mean age was 53.3 years, and men comprised 53 (63.9%) of the patients. Liver cirrhosis and diabetes mellitus were the two most common underlying diseases, followed by malignancy. The most common type of infection was acute gastroenteritis (n = 45, 54.2%), followed by biliary tract infection (n = 12, 14.5%) and primary bacteremia (n = 11, 13.3%). Other types of infection, such as peritonitis (n = 5, 6.0%), skin and soft tissue infection (SSTI) (n = 5, 6.0%), urinary tract infection (n = 3, 3.6%) and pneumonia (2, 2.4%), were rare. July and June were the most common months of occurrence of V. cholera infections. The overall in-hospital mortality of 83 patients with V. cholera infections was 7.2%, but it was significantly higher for patients with primary bacteremia, hemorrhage bullae, acute kidney injury, acute respiratory failure, or admission to an ICU. Furthermore, multivariate analysis showed that in-hospital mortality was significantly associated with acute respiratory failure (odds ratio, 60.47; 95% CI, 4.79-763.90, P = 0.002).ConclusionsNon-O1 V. cholera infections can cause protean disease, especially in patients with risk factors and during warm-weather months. The overall mortality of 83 patients with non-O1 V. cholera infections was only 7.2%; however, this value varied among different types of infection.

Clinical features of patients with carbapenem nonsusceptible Klebsiella pneumoniae and Escherichia coli in intensive care units: a nationwide multicenter study in Taiwan.

Patients in intensive care units (ICUs) are especially prone to colonization and infection by carbapenem-resistant Enterobacteriaceae. We conducted a multicenter investigation to study the clinical and microbiological characteristics of patients with carbapenem nonsusceptible Klebsiella pneumoniae and Escherichia coli in ICUs of Taiwanese hospitals. Patients with carbapenem nonsusceptible K. pneumoniae and E. coli in ICUs from nine medical centers and eight regional hospitals in Taiwan were enrolled in 2012. Carbapenem nonsusceptibility was defined as a minimum inhibitory concentration of at least 2 mg/L for imipenem or meropenem. Clinical characteristics and risk factors for 30-day mortality were analyzed. Isolates were screened for antibiotic susceptibility and β-lactamase genes. A total of 66 cases infected (n = 46) or colonized (n = 20) with carbapenem nonsusceptible K. pneumoniae (n = 60) and E. coli (n = 6) were identified during the study period. Nineteen isolates had genes that encoded carbapenemases (28.8%), including Klebsiella pneumoniae carbapenemase-2 (KPC-2) (n = 14), imipenemase-8 (IMP-8) (n = 1), Verona integron-encoded metallo-β-lactamase (VIM) (n = 3), and New Delhi metallo-β-lactamase-1 (NDM-1) (n = 1). The in-hospital mortality associated with non-susceptible K. pneumoniae and E. coli was 50%. The 30-day mortality of the 46 patients with infection was 50%. Septic shock was the only independent risk factor for 30-day mortality in patients with infection. The 30-day mortality rate was similar between patients with combination therapy and monotherapy. Patients who acquired carbapenem nonsusceptible K. pneumoniae and E. coli in ICUs have a high mortality rate. Further clinical study is needed to deal with this emerging challenge.

Clinical and microbiological characteristics of patients with septic arthritis: A hospital-based study

BackgroundTo determine the clinical and epidemiological characteristics, etiology, underlying conditions, and outcomes of patients with primary septic arthritis and no prosthetic joints at a university hospital. MethodsA retrospective study was performed between 2005 and 2012. Records from the Microbiology Department were reviewed, and patients with a positive culture of synovial fluid or biopsy were selected for the study. Clinical charts were reviewed using a designed protocol. Results41 patients were diagnosed with septic arthritis with a positive culture. Most were diagnosed with monoarticular (85.37%) and monomicrobial (92.68%) arthritis. The most commonly involved joint was the knee (34.15%). The most frequent underlying conditions were hypertension and diabetes mellitus. Staphylococcus aureus was the most common pathogen (58.54%). Two cases of chronic arthritis, both caused by Mycobacterium tuberculosis were detected. The most frequently used antibiotic combinations were cloxacillin + ciprofloxacin and vancomycin + ciprofloxacin. Surgical treatment included needle aspiration, open joint debridement, or arthroscopic techniques.Twelve cases had a poor outcome (destructive articular disease), and 3 patients died from staphylococcal sepsis. ConclusionsIn our hospital, septic arthritis is primarily acute, monoarticular, and monomicrobial; affects higher joints, is caused by S. aureus, and occurs in adult patients with underlying diseases. Outcome is good in most patients, although more than 25% of cases had articular sequels.

Caractéristiques cliniques et microbiologiques des patients atteints de kératite infectieuse sévère en période caniculaire

To study clinical and microbiological features of patients with severe microbial keratitis during a heatwave. To evaluate the links between disease severity, causative micro-organisms and temperature variation. Retrospective study of patients with microbial keratitis hospitalized in a referral center during the summer months (between June 1, 2009 and September 30, 2009), separated into two groups by date of hospitalization (heatwave vs non-heatwave). Prevalence and daytime temperatures were compared for data collected during the summers of 2009 (heatwave), 2008 (temperate) and 2003 (prolonged heatwave). Thirty-three patients were hospitalized during the summer of 2009, with an average age of 51 years and an average stay of 15 days. The primary predisposing factor was the use of contact lenses (36%), followed by pre-existing corneal disease (15%) and systemic disease (15%). Prevalence of severe keratitis was higher in periods of heatwaves vs periods of no heatwaves (mean 9.8 patients vs 3.1, P<0.001). Best corrected visual acuity progressed from 1/30 at admission to 1/10 at 1 month after discharge (P<0.001). The most common bacteria identified were Gram-positive cocci (CNS 27%) and Pseudomonas (23%). Microbiological results were similar in the two groups. Similar variations between the prevalence of severe keratitis and daytime temperatures were found for the summer of 2009 as well as for the summers of 2008 and 2003. There appears to be a link between climatic temperature variations and the prevalence of severe microbial keratitis.

Characteristics of Uropathogens in Patients with Bladder Stones

Purpose: Bladder stones is not a rare disease, however, the number of patients with bladder stones has decreased due to improvement of nutrition, hygiene, and optimal antibiotics. Bladder stones are typically found in adults with urinary stasis, such as foreign body, benign prostate hyperplasia, spinal cord injury, and urinary tract infection, and in children with congenital genito-urinary abnormality. The aim of this study was to identify the clinical and microbiological characteristics of patients with bladder stones. Materials and Methods: Patients who had bladder stones between March 2009 and December 2012 were retrospectively reviewed (Jeju National University Hospital, Jeju, Korea). We analyzed the presence of spinal cord injury, cancer, previous urinary tract calculi, and urinary tract infection associated with bladder stones and also investigated the largest diameter of bladder stone, and the number of bladder stones, as well as urine and blood culture. Results: A total of 39 patients underwent cystolithotomy or cystolithotripsy. The most common presenting symptoms were voiding disturbance (n=15, 38.5%) and hematuria (n=10, 25.6%). Of these patients, 17 (43.3%) had positive growth of organisms. Of these organisms, Escherichia coli was found in five patients, Enterococcus fecalis in three patients, Pseudomonas aeruginosa in three patients, Klebsiella pneumoniae in two patients, Staphylococcus aureus in two patients, Proteus mirabilis in one patient, and Citrobacter in one patient. Conclusions: We believe that urinary tract infection is a major risk factor in patients with bladder stones. Proper antibiotics would be required in order to reduce the risk of formation of bladder calculi. Further investigation will be needed.

41 Pediatric Tuberculosis in Two Tertiary Hospitals in Rome: A 20-Year Retrospective Study

Background and aimsTuberculosis is among the top 10 causes of child death worldwide. We aimed to describe epidemiological, clinical and microbiological features of patients with active tuberculosis admitted in two...

Biliary tract infections caused by Aeromonas species

This study investigated the clinical and microbiological characteristics of patients with Aeromonas infections of the biliary tract. Patients with bile cultures positive for Aeromonas species during the period July 2004 to December 2011 were identified from a computerized database of a hospital in Taiwan. Patients with Aeromonas infections of the biliary tract were further identified. During the study period, a total of 1,142 isolates of Aeromonas species were obtained from 750 patients. Of those patients, 91 (12.1 %) had Aeromonas infections of the biliary tract. The annual incidence (episodes per 10,000 patient-days) of biliary tract infections caused by all Aeromonas species was 0.31 in 2007, 0.12 in 2010, and 0.27 in 2011. A. hydrophila was the most common species isolated (n = 41, 45.1 %), followed by A. caviae (n = 30, 33.0 %), A. veronii biovar sobria (n = 15, 16.5 %), and A. veronii biovar veronii (n = 5, 5.5 %). The majority of patients (n = 77, 84.6 %) had polymicrobial infections. Hepatobiliary stones (n = 50, 54.9 %) and hepatobiliary cancer (n = 38, 41.8 %) were the most common underlying diseases, followed by diabetes mellitus (n = 29, 31.9 %) and liver cirrhosis (n = 7, 7.7 %). The in-hospital mortality rate was 8.8 %. Infection-related mortality was associated with underlying immunocompromised condition (p = 0.044) and use of mechanical ventilation (p = 0.004), but was not associated with inappropriate antibiotic usage or concomitant bacteremia (n = 8, 8.8 %). In conclusion, biliary tract infections caused by Aeromonas species are not uncommon and can develop in both immunocompromised and immunocompetent patients; however, patients with underlying hepatobiliary diseases are particularly susceptible to these infections.

Bacteremia caused by antimicrobial resistant Campylobacter species at a medical center in Taiwan, 1998–2008

This study was intended to delineate the clinical and microbiological characteristics of patients with bacteremia caused by Campylobacter species. Twenty-four patients with Campylobacter bacteremia were treated at the National Taiwan University Hospital from 1998 to 2008. All isolates from the 24 patients were confirmed to the species level by multiplex PCR (cadF, hipO and asp gene) and 16S RNA gene sequencing. Bacteremia was caused by Campylobacter coli in 15 (62.5%) patients, Campylobacter fetus in 6 (25%), and Campylobacter jejuni in 3 (12.5%). Of the 24 patients, 16 were male. The major underlying conditions included chronic renal insufficiency (41.7%), liver cirrhosis (37.5%), malignancy (33.3%), and previous abdominal surgery (33.3%). The most common infections were intra-abdominal infection (54.2%), followed by primary bacteremia (41.7%), and cellulitis (4.2%). The mean Pittsburgh bacteremia score was 2.5 (range, 0-9). During the bacteremic episodes, six (25%) patients developed septic shock. Third-generation cephalosporins were administered to 12 (50%) patients as empirical therapy. All-cause mortality was 4.2% at 14 days and 12.5% at 30 days. The majority of the isolates were resistant to third-generation cephalosporins and quinolones, with minimum inhibitory concentration (MIC(90)) values of 32 mg/L for cefotaxime, 128 mg/L for ceftriaxone, and 32 mg/L for both ciprofloxacin and levofloxacin. All isolates possessed a parC mutation (Arg-139-Gln) and 15 exhibited an additional gyrA mutation (Thr-86-Ile). Among these isolates, 20.8% were susceptible to erythromycin (MIC≤0.5 mg/L). Bacteremia caused by antimicrobial resistant Campylobacter species is alarming although the mortality rate is low.

Recurrent Bacteremia Caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii Complex

This study investigated the clinical and microbiological characteristics of patients with recurrent bacteremia caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex at a medical center. All ACB complex isolates associated with recurrent bacteremia were identified to the genomic species level using a 16S-23S rRNA gene intergenic spacer sequence-based method. Genotypes were determined by the random amplified polymorphic DNA patterns generated by arbitrarily primed PCR and by pulsotypes generated by pulsed-field gel electrophoresis. Relapse of infection was defined as when the genotype of the recurrent isolate was identical to that of the original infecting strain. Reinfection was defined as when the genospecies or genotype of the recurrent isolate differed from that of the original isolate. From 2006 to 2008, 446 patients had ACB complex bacteremia and 25 (5.6%) had recurrent bacteremia caused by the ACB complex. Among the 25 patients, 12 (48%) had relapse of bacteremia caused by A. nosocomialis (n = 7) or A. baumannii (n = 5). Among the 13 patients with reinfection, 5 (38.5%) had reinfection caused by different genospecies of the ACB complex. Most of the patients were immunocompromised, and most of the infection foci were catheter-related bloodstream infections. The overall in-hospital mortality rate was 33.3%. A. baumannii isolates had lower antimicrobial susceptibility rates than A. nosocomialis and A. pittii isolates. In conclusion, relapse of ACB complex bacteremia can develop in immunocompromised patients, especially those with central venous catheters. Molecular methods to identify the ACB complex to the genospecies level are essential for differentiating between reinfection and relapse of bacteremia caused by the ACB complex.