Evaluation of real time polymerase chain reaction and enzyme immunoassay in diagnosis of clostridium difficile infection

Background: Clostridium difficile infection [CDI] is the most common cause of antibiotic associated diarrhea [AAD]. Rapid diagnosis of CDI is essential to prevent hospital spread of infection

Objectives: The aim of this work were to determine the prevalence of CDI among cases of AAD in Zagazig University Hospitals, identify risk factors, and evaluate real-time polymerase chain reaction [PCR] and enzyme immunoassay [EIA], against toxigenic culture [TC]

Methodology: Stools were collected from 150 patients with AAD

Results: They were tested for TC, toxin A/B EIA, and C. difficile tcdA/tcdB genes. Thirty four toxigenic C. difficile isolates were obtained [22.7%] out of the 150 patients and those patients were considered positive for CDI. On the other hand, 6 non-toxigenic C. difficile isolates were obtained [4%], while culture of the remaining 110 patients [73.3%] did not yield C. difficile. The later 116 patients [77.3%] were considered negative for CDI. Analysis of risk factors revealed that advanced age, prolonged hospitalization, long duration of antibiotic intake, potentiated penicillins, 3rd generation cephalosporins, antibiotic combined therapy, liver cirrhosis, malignancy, proton pump inhibitors, enteral tube feeding, and cancer chemotherapy were significantly associated with CDI. Sensitivitiy, specificitiy, positive predictive value, negative predictive value, and accuracy of real-time PCR against TC were all 100%, however, values of EIA were 79.4%, 100%, 100%, 94.3%, 95.3%, respectively

Conclusions: CDI is an underappreciated nosocomial infection predisposed by many risk factors. Real-time PCR proved superior diagnostic performance to toxin A/B EIA

Biofilm formation and the presence of intercellular adhesion locus "ica" among staphylococcal from catheter associated infections

Catheter infections are most commonly caused by staphylococci, either coagulase negative [CONS] or Staphylococcal aureus [S. aureus]. It has been established that clinical isolates often produce a biofilm, which is involved in adherence to biomaterials and provides enhanced resistance of bacteria against host defences and antibiotic treatment. This study aims to detect the biofilm forming ability of staphylococcal clinical isolates evaluated by Congo red agar plate test [CRA] and spectrophotometer, and to determine the occurrence of the of the icaA and icaD genes for biofilm production by PCR. This study included 50 staphylococcal strains 26 [52%] CONS and 24 [48%] S. aureus isolated from urine catheters, central venous catheters, peripheral venous catheters, collected from 137 catheterized patients attending neonatal, internal medicine and surgical intensive care units [ICUs] and 20 strains, [10 [50%] CONS, 10 [50%]] S. aureus] isolated from skin and nasal swabs collected from 40 healthy volunteers as a control group. The results showed that according to CRA, 14 [53%] CONS and 18 [75%] S. aureus strains were biofilm producers. While quantitative detection showed that 10 [38.4%] CONS and 14 [58.3%]S. aureus were strong biofilm forming, 2 [7.6%] CONS and 4 [16.6%] S. aureus strains were weak biofilm producers, and all strains of control group were non biofilm forming. Both icaA and icaD genes were present in 17 [65.5%] CONS and 19 [79.1%] S. aureus strains, [6 strains were PCR positive and negative with the other two tests] and absent in all strains of the control group. We concluded that CRA, spectrophotometer and PCR are all valid tests and we can use any of them in the diagnosis of catheter associated biofilm formation, the choice depends on the health condition of the patient, PCR is a rapid tool for diagnosis especially because a large number of catheterized patients are critically ill and rapid diagnosis is required