**2.6. Infections of the skin and soft tissues**

**Hospital-acquired bacterial meningitis (HABM)** may be the result of an invasive procedure (craniotomy, insertion of internal or external ventricular catheter, lumbar puncture, intrathecal medication, spinal anaesthesia), of a complicated cranial trauma or, in more rare cases, of an infectious metastasis in patients with hospital-acquired bacteraemia. Such meningitis is caused by microorganisms with different spectra from community-acquired cases, and the

Bacterial meningitis is a redoubtable complication of craniotomy, occurring in 0.8–1.5% of the patients who undergo this procedure. One-third of the post-craniotomy meningitis cases develop during the first week after the surgical intervention, another third during the second week and one-third after the second week from the intervention, sometimes even years after the surgical procedure. The risk of post-surgical meningitis may be minimised by the attentive use of surgical techniques, especially those which decrease the possibility of liquid fistulae. Other factors associated with meningitis after craniotomy include concomitant infection

The incidence of meningitis associated with internal ventricular catheters (cerebrospinal shunt) used in the treatment of hydrocephaly varies between 4 and 17%. The most important causative factor is the colonisation of the catheter at the time of insertion so that most infec-

External ventricular catheters are used to monitor intra-cranial pressure or to temporarily deviate the CSF if there is an obstruction in the system or as a treatment component in cases of infection of the internal catheter. The rate of external catheter-associated infection is around 8%.

The incidence of meningitis after moderate or severe cranial trauma is 1.4%. The open cranial trauma is encountered in 5% of cranial trauma and is complicated by meningitis in 2–11% of cases. Most patients in whom meningitis occurs as a complication of closed cranial trauma present a skull base fracture, which creates a communication between the sub-arachnoid space and the sinus cavities, posing an infection risk of up to 25%. The average time interval between the trauma and the onset of meningitis is 11 days. The CSF leak is the major risk factor, even though most post-traumatic leaks are not diagnosed. Most fistulae resolve spontaneously within 7 days, a surgical intervention is recommended if the breach persists. The

The diagnostic procedure relies on neuroimagistic investigations, CSF analysis (cell count, biochemical tests for glucose, proteins, Gram staining, cultures) and blood cultures. Neuroimagistics is indicated in most patients as it allows the ventricular size evaluation and brings information on a possible poor functioning of the shunt or the presence of residual catheters after previous

The most frequently encountered bacteria in these cases are Gram-negative bacilli (*Klebsiella* 

The empirical antibiotic therapy in HABM depends on the pathogenesis of the infectious process. In patients with meningitis occurring after neurosurgical interventions, or in patients with long-term hospitalisation after open cranial trauma or skull base fractures, vancomycin is associated with cefepime, ceftazidime or meropenem; the second antibiotic is selected

*pneumoniae*, *Pseudomonas aeruginosa*), *S. aureus* and coagulase-negative staphylococci.

disease is the result of particular pathogenetic mechanisms.

26 Current Topics in Intensive Care Medicine

at the incision site and duration of procedure exceeding 4 h.

tions become manifest in less than 1 month from the procedure.

cranial trauma is the most frequent cause of recurrent meningitis.

surgical interventions.

With the increasing incidence of MRSA, skin and soft tissue infections require more frequent admission of patients presenting tissue necrosis, fever, hypotension, intense pain, altered consciousness, respiratory, hepatic or renal failure, to the ICU. When choosing the therapeutic scheme, the possibility of a polymicrobial infection must be considered, with consecutive need to cover not only MRSA but also Gram-negative and anaerobic bacteria. An inadequate initial empirical treatment is associated with prolonged evolution and hospital stay [25].

Perianal infections and abscesses, infected decubitus ulcers, and moderate and severe infections of the diabetic foot frequently involve multiple aetiologies and require coverage for streptococci, MRSA, aerobic and anaerobic Gram-negative bacilli until the results of microbiological investigations become available.

In the case of patients with non-suppurative cellulitis, a beta-lactam antibiotic, such as cefazolin, may be initially prescribed, which is to be replaced in case of unsatisfactory clinical evolution. The replacement will be made according to the result of the antimicrobial susceptibility test or with an antibiotic active on MRSA, if the pathogen has not been isolated in the culture. The empirical treatment of MRSA infections may include vancomycin, linezolid, daptomycin, tigecycline and telavancin. Linezolid, daptomycin, vancomycin and telavancin additionally also cover streptococcal infections and not only MRSA.

In case of a documented or suspected staphylococcal infection, the recommendation is to immediately initiate the antibiotic treatment according to maximal probability criteria and according to local data on the sensitivity of strains circulating in the respective area. The doses of antibiotic must be adequate, because sub-inhibitory concentrations favour the release of staphylococcal toxins and virulence factors (PVL—Panton-Valentine leukocidin), which trigger the onset of skin, lung or bone necrotic lesions. Catheters and intra-vascular devices must be removed. In cases with detected abscesses, these should be drained; the localised infection of a prosthetic joint requires the removal of the prosthesis, but if the infection is located on a valvular prosthesis, its removal is not always required.

The treatment of MRSA infections frequently includes the administration of vancomycin. The increased vancomycin consumption has posed an increasing selection pressure of staphylococcal strains resistant to this antibiotic. The concentration of vancomycin required to inhibit most *S. aureus* strains is 0.5–2 mg/l. The strains with a minimum inhibitory concentration (MIC) of vancomycin between 8 and 16 mg/l are classified as intermediate sensitive or VISA (vancomycin-intermediate *S. aureus*), while strains with MIC ≥32 mg/l are considered resistant or vancomycin-resistant *S. aureus* (VRSA). The resistance mechanisms are different in the two types of strains: in VISA strains, the bacterial cell wall is thickened by the altered biosynthesis process and the glycopeptides targets are hidden in its thickness and in the case of VRSA strains, the target of glycopeptides is itself modified.

**3. Management of antibacterial chemotherapeutic drugs**

**Table 4.** Risk of post-surgical wound infection depending on the Altemeier classification.

• the characteristics of the isolated or suspected aetiological agent,

(age, physiological status, comorbidities, infection site),

• patient characteristics, which may influence the efficiency and toxicity of the treatment

Infections and Multidrug-Resistant Pathogens in ICU Patients

http://dx.doi.org/10.5772/intechopen.79229

29

• pharmacodynamic and pharmacokinetic characteristics of the antibiotic (adsorption, tissue distribution, concentration in the infectious focus, metabolisation and elimination of the

In the case of the critical patients, the early administration of an effective antibiotic treatment is essential and determining, the time until the initiation of therapy being a strong predictor of mortality. A retrospective cohort study showed that the delay of effective treatment after the onset of recurrent or persistent hypotension was associated with an increased death risk; the survival rate in patients with treatment administered during the first hour was of 79.9%, with

*Optimization of doses*. The antibiotic requirement is calculated depending on the characteristics of the patient (age, weight, renal function), on the pathogenic microorganism, infection site

each hour of delay in antibiotic therapy leading to a 7.6% decrease in this rate [27].

The choice of antibiotics is conditioned by:

**Table 3.** Risk indexes for post-surgical wound infections.

antibiotic).

**Surgical wound infections** are another category of infections frequently confronting ICUs. In their most frequently polymicrobial aetiology, Gram-positive cocci (especially MRSA), *Enterobacteriaceae* and non-fermentative Gram-negative bacilli (*P. aeruginosa*) are among the most frequently isolated pathogens. The empirical treatment of these infections consists of associating cefepime or meropenem with an aminoglycoside or a fluoroquinolone.

Many extrinsic risk factors are inter-connected with intrinsic factors or are found in association, for which reason, the Study on the Efficacy of Nosocomial Infections Control (SENIC), a risk index, has been proposed for surgical wound infections. When compared to the traditional Altemeier system, this index predicts the risk of post-surgical infection two times better and the inclusion of other items does not seem to improve its predictive capacity [26]. The National Surveillance System of Nosocomial Infections in the USA proposed the NNIS risk index, further completed with the item on the use of laparoscopic techniques (**Tables 3** and **4**).


**Table 3.** Risk indexes for post-surgical wound infections.

streptococci, MRSA, aerobic and anaerobic Gram-negative bacilli until the results of micro-

In the case of patients with non-suppurative cellulitis, a beta-lactam antibiotic, such as cefazolin, may be initially prescribed, which is to be replaced in case of unsatisfactory clinical evolution. The replacement will be made according to the result of the antimicrobial susceptibility test or with an antibiotic active on MRSA, if the pathogen has not been isolated in the culture. The empirical treatment of MRSA infections may include vancomycin, linezolid, daptomycin, tigecycline and telavancin. Linezolid, daptomycin, vancomycin and telavancin additionally

In case of a documented or suspected staphylococcal infection, the recommendation is to immediately initiate the antibiotic treatment according to maximal probability criteria and according to local data on the sensitivity of strains circulating in the respective area. The doses of antibiotic must be adequate, because sub-inhibitory concentrations favour the release of staphylococcal toxins and virulence factors (PVL—Panton-Valentine leukocidin), which trigger the onset of skin, lung or bone necrotic lesions. Catheters and intra-vascular devices must be removed. In cases with detected abscesses, these should be drained; the localised infection of a prosthetic joint requires the removal of the prosthesis, but if the infection is located on a

The treatment of MRSA infections frequently includes the administration of vancomycin. The increased vancomycin consumption has posed an increasing selection pressure of staphylococcal strains resistant to this antibiotic. The concentration of vancomycin required to inhibit most *S. aureus* strains is 0.5–2 mg/l. The strains with a minimum inhibitory concentration (MIC) of vancomycin between 8 and 16 mg/l are classified as intermediate sensitive or VISA (vancomycin-intermediate *S. aureus*), while strains with MIC ≥32 mg/l are considered resistant or vancomycin-resistant *S. aureus* (VRSA). The resistance mechanisms are different in the two types of strains: in VISA strains, the bacterial cell wall is thickened by the altered biosynthesis process and the glycopeptides targets are hidden in its thickness and in the case

**Surgical wound infections** are another category of infections frequently confronting ICUs. In their most frequently polymicrobial aetiology, Gram-positive cocci (especially MRSA), *Enterobacteriaceae* and non-fermentative Gram-negative bacilli (*P. aeruginosa*) are among the most frequently isolated pathogens. The empirical treatment of these infections consists of

Many extrinsic risk factors are inter-connected with intrinsic factors or are found in association, for which reason, the Study on the Efficacy of Nosocomial Infections Control (SENIC), a risk index, has been proposed for surgical wound infections. When compared to the traditional Altemeier system, this index predicts the risk of post-surgical infection two times better and the inclusion of other items does not seem to improve its predictive capacity [26]. The National Surveillance System of Nosocomial Infections in the USA proposed the NNIS risk index, further completed with the item on the use of laparoscopic

associating cefepime or meropenem with an aminoglycoside or a fluoroquinolone.

biological investigations become available.

28 Current Topics in Intensive Care Medicine

also cover streptococcal infections and not only MRSA.

valvular prosthesis, its removal is not always required.

of VRSA strains, the target of glycopeptides is itself modified.

techniques (**Tables 3** and **4**).


**Table 4.** Risk of post-surgical wound infection depending on the Altemeier classification.
