Infection control interventions affected by resource shortages: impact on the incidence of bacteremias caused by carbapenem-resistant pathogens.

We evaluated an infection control (IC) program influenced by personnel and material resource shortages on the incidence of bloodstream infections (BSI) due to carbapenem-resistant Klebsiella pneumoniae (CRKP), Acinetobacter baumannii (CRAB), and Pseudomonas aeruginosa (CRPA) in an endemic region. Between January 2010 and December 2015, all BSI episodes caused by CRKP, CRAB, and CRPA were recorded. An IC bundle was implemented in January 2012. We evaluated the effect of the interventions on BSI rates between the pre-intervention (2010-2011) and intervention (2012-2013) periods, using an interrupted time-series model. From 2014, when interventions were still applied, BSI incidence was gradually increased. For this reason, we evaluated with a linear mixed effects model several factors possibly contributing to this increase for the years 2012-2015, which was considered as the intervention/follow-up period. During the study period, 351 patients with BSI were recorded, with a total of 538 episodes; the majority (83.6%) occurred in the intensive care unit (ICU). The BSI incidence rate per year during 2010-2015 for ICU patients was 21.03/19.63/17.32/14.45/22.85/25.02 per 1000 patient-days, respectively, with the reduction in BSI levels after the start of intervention marginal (p = 0.054). During the follow-up period (2014-2015), the most influential factors for the increased BSI incidence were the reduced participation in educational courses and compliance with hand hygiene. The implementation of IC interventions reduced the BSI incidence rates, particularly for ICU patients. However, factors possibly related to the restrictions of human and material resources apparently contributed to the observed expansion of BSI in our endemic setting.

First-year results of an antibiotic stewardship program in a Greek tertiary care hospital.

The aim of this study was to investigate the effect of the implementation of an antibiotic stewardship program (ASP) on antibiotic consumption in our 428-bed hospital. The Infection Control Committee implemented an ASP beginning in January 2016, aiming to reduce inappropriate antibiotic use through improved prescribing practices. The ASP included both pre-authorization and prospective audit and feedback strategies. We collected pharmacy and hospital data for the years 2015 (pre-intervention) and 2016 (post-intervention). Consumption data were expressed as daily defined doses (DDDs) per 100 patient-days (PD) and the significance of the differences between 2015 and 2016 was assessed by paired t-test. Antibiotic resistance rates for the most important hospital pathogens were monitored for 2015-2016. The ASP effectively reduced consumption of most antimicrobials; total antibiotic use decreased by 16.7% (from 104.3 in 2015 to 86.9 DDDs/100 patient-days in 2016, p < 0.001) owing to reduction of 19.1% for non-restricted and 13.8% for restricted antibiotics. Important restricted antimicrobials, such as colistin, carbapenems, quinolones and tigecycline showed significantly decreased usage post-intervention. Significant changes in the resistance rates were not observed, except a decreasing trend for colistin and tigecycline (Acinetobacter baumannii and Klebsiella pneumoniae) and also vancomycin (enterococci). The ASP was successful in terms of reducing the antibiotic consumption for the first year of its implementation. Interestingly, antimicrobials requiring pre-authorization exhibited a lower reduction than other antibiotics. Potential effects of the ASP in reducing resistance rates remain to be shown.

Effect of ceftriaxone on the outcome of murine pyelonephritis caused by extended-spectrum-ß-lactamase-producing Escherichia coli.

Urinary tract infections (UTIs) due to extended-spectrum-ß-lactamase (ESBL)-producing Enterobacteriaceae in children are becoming more frequent, and they are commonly treated initially with a second- or third-generation cephalosporin. We developed a murine model of ascending UTI caused by ESBL-producing Escherichia coli. Using this model, we investigated the renal bacterial burden, interleukin-6 (IL-6) expression, and histopathological alterations caused by ESBL- and non-ESBL-producing bacteria after 1, 2, or 6 days with or without ceftriaxone therapy. The renal bacterial burden, IL-6 concentration, and histological inflammatory lesions were not significantly different between mice infected with ESBL- and non-ESBL-producing bacteria without treatment at any of the time points examined. Following ceftriaxone administration, the bacterial burden was eliminated in the kidneys of mice infected with ESBL- and non-ESBL-producing bacteria on the 6th postinfection day. The histological analysis demonstrated that among mice treated with ceftriaxone, those infected with ESBL-producing bacteria had more profound renal alterations than those infected with non-ESBL-producing bacteria on the 6th day (P < 0.001). In comparison, microbiological outcomes did not differ significantly between mice infected with ESBL- and non-ESBL-producing bacteria at any of the time points examined. The effectiveness of ceftriaxone in mice with UTIs due to ESBL-producing E. coli may have therapeutic implications; it is, however, hampered by limited activity on the histopathological lesions, a finding that needs further investigation.

Accumulation of carbapenem resistance mechanisms in VIM-2-producing Pseudomonas aeruginosa under selective pressure.

Pseudomonas aeruginosa has the potential to achieve resistance to carbapenems via the acquisition of carbapenemase-encoding genes, the downregulation of the OprD porin, the overexpression of efflux systems and the overproduction of cephalosporinases. One hundred and fifty carbapenem-non-susceptible isolates from 2008 to 2010 were screened for carbapenemase production, OprD porin loss, efflux pumps overexpression and inducible AmpC beta-lactamase production. For comparison reasons, the presence of the same mechanisms was also assessed in a previous collection of 30 carbapenem-non-susceptible P. aeruginosa isolated between 2003 and 2005. Results showed the accumulation of various resistance mechanisms among VIM-2 producers isolated between 2008 and 2010 with a parallel considerable increase in imipenem MIC90 and the geometric mean of the MIC values of imipenem and meropenem between the two study groups. The accumulation of carbapenem resistance mechanisms highlights the potential of this formidable pathogen for evolutionary success under antibiotic selective pressure.

A large waterborne gastroenteritis outbreak in central Greece, March 2012: challenges for the investigation and management.

In March 2012, there was an unusual increase of gastroenteritis cases in a district with 37,264 inhabitants in central Greece. It was estimated that more than 3600 people developed symptoms. A 1:1 case-control study showed that consumption of tap water was a risk factor for acquiring infection [odds ratio (OR) 2.18, 95% confidence interval (CI) 1.11-4.28]. Descriptive data, low gastroenteritis incidence in adjacent areas with different water supply systems, and water-quality data further supported the hypothesis of a waterborne outbreak. Thirty-eight stool samples were positive for rotavirus. Bacterial indicators of recent faecal contamination were detected in samples from the water source and ice cubes from a local production enterprise. Molecular epidemiology of rotavirus strains, apart from the common strain, G3[P8], identified the unusual G/P combination G2P[8]. Water sanitation measures contributed to the control of the outbreak. This outbreak demonstrated the need for the cooperation of laboratories with different expertise and the importance of early notification of waterborne gastroenteritis outbreaks.

Shiga toxin-producing Escherichia coli in Central Greece: prevalence and virulence genes of O157:H7 and non-O157 in animal feces, vegetables, and humans.

In Greece, Shiga toxin-producing Escherichia coli (STEC) have only been sporadically reported. The objective of this study was to estimate the prevalence of STEC and Escherichia coli O157:H7 in farm animals, vegetables, and humans in Greece. A total number of 1,010 fecal samples were collected from farm animals (sheep, goats, cattle, chickens, pigs), 667 diarrheal samples from humans, and 60 from vegetables, which were cultured in specific media for STEC isolates. Enzyme-linked immunosorbent assay (ELISA) was used to detect toxin-producing colonies, which, subsequently, were subjected to a multiplex polymerase chain reaction (PCR) for stx1, stx2, eae, rfbE O157, and fliC h7 genes. Eighty isolates (7.9 %) from animal samples were found to produce Shiga toxin by ELISA, while by PCR, O157 STEC isolates were detected from 8 (0.8 %) samples and non-O157 STEC isolates from 43 (4.2 %) samples. STEC isolates were recovered mainly from sheep and goats, rarely from cattle, and not from pigs and chickens, suggesting that small ruminants constitute a potential risk for human infections. However, only three human specimens (0.4 %) were positive for the detection of Shiga toxins and all were PCR-negative. Similarly, all 60 vegetable samples were negative for toxin production and for toxin genes, but three samples (two roman rockets and one spinach) were positive by PCR for rfbE O157 and fliC h7 genes. These findings indicate that sheep, goats, cattle, and leafy vegetables can be a reservoir of STEC and Escherichia coli O157:H7 isolates in Greece, which are still rarely detected among humans.

Diversity of vanA-type vancomycin-resistant Enterococcus faecium isolated from broilers, poultry slaughterers and hospitalized humans in Greece.

OBJECTIVES: This study investigated the prevalence of vancomycin-resistant enterococci (VRE) in the broiler production environment after the avoparcin ban and their epidemiological relationship with human clinical VRE from the same geographical regions in Greece. METHODS: Caecal contents from broilers (n = 500) from eight livestock farms and faecal samples from poultry slaughterers (n = 50), all collected in two slaughterhouses during 2005-08, were analysed for species and vancomycin resistance gene identification using multiplex PCR. Sixty-three human clinical vancomycin-resistant Enterococcus faecium (VREF) isolates, obtained during 2006-09, were also examined. Discriminant analysis (DA) was used to establish the relationship of antimicrobial resistance profiles (ARPs) among broiler, poultry slaughterer and human clinical VREF. PFGE was conducted to study the genetic relatedness among VREF from the different sources. RESULTS: A total of 120 VRE were recovered from 113 (22.6%) broiler samples. VREF carrying the vanA gene were predominant, being recovered from 72 (14.4%) samples from five (62.5%) broiler farms. Concerning poultry slaughterers, VREF were recovered from 10 (20%) samples. Susceptibility testing revealed that broiler VREF were consistently resistant to tetracycline, whereas 93.7% of clinical VREF were resistant to ampicillin. Furthermore, 92.1% of clinical VREF compared with 54.4% of broiler VREF were multiresistant (resistant to at least five antimicrobial classes). DA classified broiler and human clinical VREF into their corresponding source with high classification rates (100% and 85.7%, respectively), while the classification rate of poultry slaughterer VREF was relatively low (50%), with 40% of them classified closely to broiler VREF. PFGE patterns were clearly related to the source of the VREF, with broiler isolates being clustered distinctly from all human isolates. CONCLUSIONS: A remarkable persistence of VREF was observed in the broiler production environment even >10 years after the avoparcin ban. Human and broiler VREF belonged to clearly unrelated populations, strongly indicating no clonal spread of VREF among the different sources, even between broilers and poultry slaughterers, despite them sharing common ARPs, as also supported by DA.

The acute effect of smoking in healthy and asthmatic smokers.

BACKGROUND: Acute exposure to cigarette smoke is related to airway and systemic inflammation and oxidative stress. Little is known about the acute effect of cigarette smoking in smoking asthmatics. The aim of this study was to evaluate the acute effect of smoking in airway and systemic inflammation and oxidative stress in normal smokers and patients with properly treated well-controlled persistent asthma. MATERIALS AND METHODS: Ten normal smokers and 10 smokers with moderate persistent asthma controlled with LABA and ICS were recruited. Subjects refrained from smoking for at least 12 h prior to their inclusion. We compared the effects of smoking of two cigarettes on airway obstruction, airway inflammation and oxidative stress [by measuring fraction of exhaled nitric oxide (FeNO), plus pH and 8-isoprostane in exhaled breath condensate (EBC)] before and 30, 90 and 180 min after smoking. Furthermore, we evaluated systemic oxidative stress, C-reactive protein (CRP) and serum amyloid A (SAA) and urine leukotriene E(4) (LTE(4)) before and 180 min after smoking. RESULTS: No differences were observed in EBC pH and 8-isoprostane, FeNO and systemic oxidative stress between the groups at baseline. In asthmatics, EBC pH decreased 30 min and EBC 8-isoprostane increased 90 min after smoking (P = 0.039 and P = 0.029 respectively), which was not evident in smoking controls. Serum oxidative stress increased only in asthmatic smokers at 180 min (P = 0.001). No differences were observed in SAA, CRP and urine LTE(4) levels before and after smoking. CONCLUSION: Acute smoking has more deleterious effects in well-controlled properly treated asthmatic smokers compared with matched normal smokers.

The effect of estrogens on plasma ghrelin concentrations in women.

BACKGROUND: Data regarding the possible effects of estrogen on ghrelin secretion in humans are limited and contradictory. AIM: To investigate the effect of estradiol (E2) on ghrelin levels in normal pre- and post-menopausal women. SUBJECTS AND METHODS: A total of 21 women divided into 3 groups, i.e.13 normally cycling women (no.=7, group 1 and no.=6, group 2) and 8 post-menopausal women (group 3). Women of group 1 received increasing doses of E2 through skin patches from cycle days 3 to 5. Women of group 2, underwent total abdominal hysterectomy plus bilateral salpingo-oophorectomy (TAH+BSO) on cycle day 3. Women of group 3 received po increasing doses of E2 valerate for 15 days. Acylated ghrelin and E2 were measured in all blood samples. RESULTS: In group 1, plasma ghrelin levels did not show any significant changes for the week following cycle day 3. In group 2, ghrelin levels were similar before and after TAH+BSO and remained stable during the first 7 post-operative days. In group 3, no significant changes in plasma ghrelin levels were seen during the 15 days of E2 administration. CONCLUSIONS: The present study demonstrates for the first time that ghrelin values were not affected either by exogenous short-term estrogen administration to pre- and post-menopausal women or following ovariectomy in pre-menopausal women. It is suggested that ovarian hormones are not involved in the regulation of ghrelin secretion in women.

Impact of bloodstream infections caused by carbapenem-resistant Gram-negative pathogens on ICU costs, mortality and length of stay.

BACKGROUND: The aim of this study was to estimate the impact of bloodstream infections (BSIs) caused by carbapenem-resistant Gram-negative (CRGN) pathogens on hospital costs, mortality and length of stay (LOS). METHODS: All patients hospitalized for ≥3 days in the Intensive Care Unit (ICU) of a tertiary-care general hospital from 1/1/2015 to 31/12/2017 were included in the study. A retrospective case-control study was performed in order to examine the difference in medical, pharmaceutical and operating costs, LOS and in-hospital mortality between patients with BSI caused by CRGN/without BSI (cases/controls, respectively). The statistical analysis was performed using the SPSS software (v23.0). RESULTS: A total of 419 patients (67.5% males, median age 60.0 years) were included in the analysis (142 cases/277 controls); 10 patients with non-CRGN BSIs were excluded. Overall mortality was 33.7% (49.3/25.6% in cases/controls). The median LOS and total cost were 30.0 vs. 12.0 days and 20 359.1 vs. 8,509.3 €, respectively, between patients with/without CRGN BSIs. After adjusting for baseline demographics, underlying disease severity and patients' specialties, CRGN BSIs remained a significant factor in mortality (odds ratio 2.9; 95% confidence interval 1.8-4.8; p <0.001). Additionally, CRGN BSIs seem to result in significantly prolonged LOS and extra cost per infected patient (p <0.001). CONCLUSIONS: ICU patients with CRGN BSI are at increased risk for mortality and prolonged hospitalization and incur higher costs, imposing a heavy burden on healthcare system. Infection control strategies, considering also the cost-efficacy of interventions, are crucial in order to control the expansion of CRGN infections.

Microbiological diagnostics of bloodstream infections in Europe-an ESGBIES survey.

OBJECTIVES: High-quality diagnosis of bloodstream infections (BSI) is important for successful patient management. As knowledge on current practices of microbiological BSI diagnostics is limited, this project aimed to assess its current state in European microbiological laboratories. METHODS: We performed an online questionnaire-based cross-sectional survey comprising 34 questions on practices of microbiological BSI diagnostics. The ESCMID Study Group for Bloodstream Infections, Endocarditis and Sepsis (ESGBIES) was the primary platform to engage national coordinators who recruited laboratories within their countries. RESULTS: Responses were received from 209 laboratories in 25 European countries. Although 32.5% (68/209) of laboratories only used the classical processing of positive blood cultures (BC), two-thirds applied rapid technologies. Of laboratories that provided data, 42.2% (78/185) were able to start incubating BC in automated BC incubators around-the-clock, and only 13% (25/192) had established a 24-h service to start immediate processing of positive BC. Only 4.7% (9/190) of laboratories validated and transmitted the results of identification and antimicrobial susceptibility testing (AST) of BC pathogens to clinicians 24 h/day. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry from briefly incubated sub-cultures on solid media was the most commonly used approach to rapid pathogen identification from positive BC, and direct disc diffusion was the most common rapid AST method from positive BC. CONCLUSIONS: Laboratories have started to implement novel technologies for rapid identification and AST for positive BC. However, progress is severely compromised by limited operating hours such that current practice of BC diagnostics in Europe complies only partly with the requirements for optimal BSI management.

Changes in antimicrobial resistance of clinical isolates of Acinetobacter baumannii group isolated in Greece, 2010-2015.

In recent years, hospitals in southeastern Europe have faced dramatically high rates of antibiotic-resistant Acinetobacter baumannii. We analysed the evolution of resistance among clinical isolates of A. baumannii group obtained from nine tertiary hospitals throughout Greece over 6 years (2010-2015). Identification and antimicrobial susceptibility testing were performed using Vitek 2 or Microscan walkaway automated systems. Between 2010 and 2015, resistance to ampicillin/sulbactam increased from 46.2 to 88.2 % (P=0.021), resistance to gentamicin increased from 69.3 to 86.4 % (P=0.014) and resistance to tobramycin increased from 59.8 to 76.8 % (P=0.011). Imipenem resistance rates were consistently very high, ranging from 90.3 % in 2010 to 94.5 % in 2015 (P=0.198), while meropenem resistance rates increased from 82.6 % in 2010 to 94.8 % in 2015 (P=0.006). Resistance rates to trimethoprim/sulfamethoxazole showed a remarkable decreasing trend, declining from 90.2 % in 2010 to 69.1 % in 2015 (P=0.035). These evolutions render the treatment of A. baumannii infections particularly challenging and underline the need for enhanced infection control measures.

Evaluation of high-risk human papillomavirus types PCR detection in paired urine and cervical samples of women with abnormal cytology.

BACKGROUND: During the last decade, increasing efforts have focused on HPV detection in self-obtained samples, to increase the overall proportion of patients participating in cervical cancer screening procedures. OBJECTIVES: A clinical evaluation study of an optimized protocol for PCR detection of high-risk human papillomavirus (HPV) types in urine compared with cervical samples in consecutive women referred to the colposcopy clinic with abnormal cervical cytology. STUDY DESIGN: Paired urine and cervical specimens were collected from 100 consecutive women referred to the colposcopy clinic with abnormal cervical cytology and normal urine parameters. In-house and a commercial PCR method for the detection of HPV types 16 and 18, and a commercial multiplex PCR for HPV types 6, 11, 16, 18, and 33 were performed. All HPV cervix-positive/urine-negative paired urine samples were spiked with serial dilutions of cell lines infected with HPV 16 or 18 to test the sensitivity of HPV detection in these urine samples. RESULTS: In all but two cases HPV type 16 was detected. In cancer cases, the urine/cervix HPV detection sensitivity was 88.8%; in cases with high-grade lesions it was 76.5%; and in cases with low-grade lesions it was 45.5%. In all concordant cases the same HPV type was detected in both samples. The urine/cervix HPV detection sensitivity was higher when urine samples contained two or more epithelial cells per field in urine microscopy. HPV detection in 9 cervix-positive but urine-negative urine samples spiked with serial dilutions of HPV-positive cell lines showed that in these cases urine PCR inhibitors did not affect PCR amplification. CONCLUSIONS: A higher urine/cervix HPV detection sensitivity in cancer and high-grade lesions suggests that urine testing could be used to detect HPV mainly when these lesions are present.

Outbreak of infections in a Greek university hospital involving a single clone of high-level aminoglycoside-resistant Enterococcus faecalis.

Among 145 Enterococcus faecalis isolates recovered during a 15-month period (April 1997-June 1998) in AHEPA University Hospital, Thessaloniki, Greece, 94 (65%) exhibited high-level resistance to gentamicin or streptomycin and 61 (42%) to both aminoglycosides; 73% of the high-level aminoglycoside-resistant E. faecalis isolates belonged to a single clone carrying the gene aac(6')-Ie-aph(2")-Ia. These findings differ from those of other regions, where high-level aminoglycoside-resistance genes are dispersed into genetically unrelated strains.

Changes in serum lipids and lipoproteins in cancer patients during chemotherapy.

We studied serum lipid and lipoprotein changes occurring during chemotherapy in 57 patients with chemosensitive cancers, including 18 malignant lymphomas, 18 breast carcinomas, 14 small-cell lung carcinomas, and 7 urothelial-cell carcinomas. Patients who responded favorably to chemotherapy demonstrated a significant increase in serum total cholesterol and LDL cholesterol values, with the singular exception of breast-cancer patients, who exhibited a nonsignificant decrease in both of these parameters. Serum levels of free cholesterol and HDL cholesterol did not show any significant changes. Finally, serum triglycerides tended to increase after effective chemotherapy, but this was of statistical significance only in breast-cancer patients. Although our findings were based on a rather small number of patients, they indicate that the lipid and lipoprotein disorders reported in cancer patients are reversible by effective treatment of the tumor, suggesting that these disorders are a secondary phenomenon of malignancy.

Multiresistant Acinetobacter baumannii isolates in intensive care units in Greece.

One hundred and twenty-one clinical isolates of Acinetobacter baumannii recovered from the intensive care units (ICUs) of nine tertiary-care hospitals in Athens, Greece were studied in order to determine whether the increasing appearance of resistant acinetobacters is due to the spread of epidemic strains. The majority of the isolates exhibited resistance to ampicillin-sulbactam, and the most common antibiotic resistance profiles comprised resistance to nine and eight of the 11 potentially active antibiotics tested, respectively. Pulsed-field gel electrophoresis showed that 68% of the isolates, recovered from all ICUs, belonged to two clonal groups, indicating inter-hospital dissemination of multiresistant A. baumannii in our region.

Methicillin-resistant Staphylococcus aureus in the hospitals of central Greece.

A total of 250 consecutive Staphylococcus aureus clinical isolates were collected during the period 1999-2000 from the five major hospitals of the district of Thessaly (Central Greece). Thirty seven (14.8%) of the isolates were mecA-positive (MRSA) in a PCR-based assay; all exhibited resistance to oxacillin (agar dilution MICs > or =4 mg/L) and were also resistant to multiple antibiotics. Most of the MRSA isolates had been collected in the intensive care units and the surgical wards of the participating hospitals in a sporadic fashion. The MRSA incidence found here was significantly lower than reported in previous studies from Greece. Molecular typing by PFGE showed that the MRSA isolates were distributed between three pulsotypes. Evaluation of various conventional methods for assessing methicillin resistance showed that oxacillin agar dilution and immunological detection of PBP2a with the Slidex MRSA Detection kit were the most reliable in this setting. Misclassifications of isolates exhibiting low-level resistance (oxacillin MIC 2-4 mg/L) occurred with the salt agar screen, the oxacillin disk diffusion and the ATB Staph System methods.

Soft-tissue abscess involving Actinomyces odontolyticus and two Prevotella species in an intravenous drug abuser.

Skin and soft-tissue infections in intravenous users comprise a variety of microorganisms and anaerobic bacteria are frequently involved in these suppurative infections. A case of subcutaneous abscess into anterior femoral muscles involving Actinomyces odontolyticus and two Prevotella species (Prevotella buccae and Prevotella melaninogenica) in an intravenous drug abuser is presented. This combination of microorganisms has not previously been described in soft-tissue infections. The patient volunteering that he licked his hypodermic needle prior to cocaine injection supports that the implicating bacteria originated from the oral cavity. Eventually, the patient recovered and at a 6-month follow-up a gradual improvement of his subcutaneous infection was noticed.

Study on the use of an enzyme-linked immunosorbent assay in determining human antibodies to diphtheria toxin as compared with a reference toxin neutralization assay.

Serum samples from 156 Greek persons were assessed by an IgG-specific enzyme-linked immunosorbent assay (ELISA) and a reference tissue culture toxin-neutralization (TN) assay for the quantitation of diphtheria toxin antibodies. By the reference method, 7.7% of the persons were susceptible to diphtheria (antitoxin < 0.01 IU/ml), 28.8% had basic protection (antitoxin 0.01-0.09 IU/ml) and 63.5% were fully protective (antitoxin > or = 0.1 IU/ ml), while the corresponding figures were 17.9, 36.5 and 45.5% when they were tested by the immunoassay. None of the samples been susceptible by the TN assay were found to have some protection when tested by ELISA. However, three (6.7%) of the 45 samples showing a basic protection with TN, were fully protective when titrated by the immunoassay. In addition, 31 (31.3%) of the 99 samples been fully protective by the bioassay, were found to be either basically protective or susceptible by means of the ELISA. Overall, validity features of the immunoassay were: sensitivity 68.7%, specificity 94.7%, positive predictive value 95.8% and negative predictive value 63.5%. The ELISA tested in our study could be used to determine diphtheria antitoxin in individuals needed a booster immunization (susceptible or basic protective samples), although it might falsely include in the above categories samples that are within the fully protective levels of antibodies.