Bacterial infections complicating skin diseases

ABSTRACT

Secondary infection of skin lesions is a common and serious problem. They can be potentially life threatening and may progress rapidly; therefore, their early recognition and proper management are important.The study was conducted on 60 patients suffering from various skin diseases with secondary infection on top, "37 outpatients and 23 inpatients" attended Ain Shams University Hospitals from April-December 2005.Bacteriological examination of purulent exudates from the deeper part of secondarily infected lesions was done. Antibiotic sensitivity pattern and production of beta-lactamase "for Gram +ve cocci" and extended spectrum beta-lactamase [ESBL] "for Gram-ve bacilli" were tested.We found that S.aureus was the most common isolated organism [83.3%] of all cases, followed by Gram-negative enteric bacteria which were isolated from [21.7%] of cases. These were followed by Streptococcus pyogenes and Pseudomonas aeruginosa with an incidence of [15%] and [6.7%] respectively. Enterococci were detected in only [5%] of cases. Coagulase negative [CONS] and anaerobic gram-positive cocci were the least isolated organisms each found only in one case.Within the Enterobacteriaceae group; E.coli and Proteus species were the most commonly isolated organisms, each representing [30.8%] of the total isolated Gram-negative enteric bacteria.There was significant difference between in and/out- patients as regard the antibiotic sensitivity pattern of both S.aureus and the Enterobacteriaceae group. The S.aureus strains isolated from the inpatients showed more resistance to Amoxycillin+clavulonic acid, cefaclor, erythromycin, fusidic acid, methicillin, ofloxacin, tobramycin and vancomycin. The rate of MRSA in hospitalized patients was [26.3%] versus [9.7%] in outpatients. The Enterobacteriaceae bacteria strains isolated from the hospitalized patients were more resistant to cefaclor, levofloxacin and ofloxacin.All Enterococci isolates from both the in/ and outpatients were sesnsitive to chloramphenicol, ofloxacin and were resistant to oxacillin. No VRE were detected from the inpatients, while 50% of isolates were resistant to vancomycin in the outpatient group.P.aeruginosa isolates from both the in/ and outpatient groups were sensitive to amikacin, cefoperazone, and levofloxacin and were resistant to cefepime. Resistance to imipenem and piperacillin was more in the inpatient group, while resistance to cephazolin was more in the outpatient isolates.Sensitivity to aztreonam was more in the outpatient isolates.The incidence of beta-lactamase production by the Gram-positive cocci was [96%] which coincides with the high resistance of these organisms to penicillin and ampicillin. Whereas; the incidence of ESbetaL production by the Gram-negative bacilli was [29.4%] with no significant difference between inpatients and outpatients although it was higher in inpatients. In conclusion, this study showed that S.aureus is the most common cause of secondary infection in all skin lesions and was isolated from all body sites with nearly equal prevalence in inpatients and outpatients. The incidence of Enterobacteriaceae infection was more in inpatients with higher levels of ESbetaL production. Resistance of different bacterial isolates to antibiotics was also higher in inpatients